THE MOST MERCIFUL,
THE BENEFICIENT”
And we split the earth in fragments, and produce there in corn,
And grapes dense with lofty trees, and fruit and fodder,
For use of convenience to you and your cattle,
(Al-Quran, Surah Abbas 80, Ayat 25-32)
I
FRUIT PRODUCTION AND QUALITY OF KINNOW
MANDARIN
requirements for the degree of
DOCTOR OF PHILOSOPHY
ALLAH SUBHANAHU WA TA'ALA,
Afterwards To
My Father in Heaven
Muhammad Afzal Qureshi (LATE)
A strong and gentle soul who always encouraged me to achieve higher
aims in life. I missed him at every step.
My Mother
Mrs. Shaheen Afzal
Who lives in my mind and soul, whose love will never mitigate, whose
prayers will never die, who is nearest, deepest and dearest to me
My Sister
Ammara Afzal
VII
ACKNOWLEDGMENT
All praises are to Allah SWT the Glorious, the Lord, the Merciful and the Compassionate,
who has given me the blessing to accomplish this Thesis. Further May peace and salutation
be given to my beloved Prophet Hazrat Muhammad (SAW) who has taken all human
beings from the darkness to the lightness. It’s a matter of great admiration and pleasure to
explicit deep commitment and devotion of appreciation to my Supervisor Dr. Muhammad
Jafar Jaskani, Professor, Institute of Horticultural Sciences UAF, for designing this splendid
research project. It was principally due to my supervisor’s educational guidance and nice
consulting behavior that this work was planned, executed and completed successfully.
I extend my appreciation to the members of my supervisory committee, Dr. Ahmad Sattar
khan, Associate Professor, IHS, UAF for his helping and admirable behavior. I am highly
thankful for his valuable suggestions. I am also thankful to Dr. Rashid Ahmad, Professor,
Department of Agronomy, UAF for his precious and continuous guidelines during the
research activities and kind hearted behavior throughout my doctoral studies. I am thankful to
Higher education commission, Pakistan for awarding me scholarship under Indigenous
Ph.D. Fellowship program (Phase II, Batch IV). I gratefully acknowledge the kind and
cooperative behavior of Dr. Razia, Research officer, Central Hi-Tech laboratory, UAF, for
guiding and helping me during HPLC analysis. I am thankful to field staff at Postgraduate
Agriculture Research station (PARS) UAF, for their kind cooperation during the whole
research activities. I will highly acknowledge the affectionate behavior of Mr. Muhammad
Nawaz, Lab technician, Plant tissue culture cell, IHS, UAF, for making possible the
availability of chemicals and instruments during the whole course of research. I am thankful
to Mr. Shakeel latif and Farhan Khalid for helping me during lab work at Pomology lab.
I will not forget to expand my heartiest gratitude’s to my respected and sympathetic seniors
Dr. Waqar shafqat, Mr. Kashif Raza, Miss Naseem Sharif, Dr. Waseem Haider and
Ahamd raza who guided and helped me at every step whenever I needed them. I will offer
special gratitude to my dearest Ph.D. fellow Safeer ud Din for his valuable suggestions and
encouraging behavior. I am also very much grateful to my juniors (Sufian Ikram, Sami Ur
Rehman, Bilal Qayum and Faraz Ayub) for their respectful and cooperative behavior with
me. I am highly indebted to my roommate cum brother Hafiz Amjad Ali Rana who always
helped me like my own and never makes me feel that anything is difficult or impossible and for
his sincere suggestions whenever I needed him. I am thankful to my best friends Hussain
Sardar, Mudassir Ali Tahir, Shehzad Sami, Ahmad Mujtaba and Muhammad Zubair for
standing with me through my thick thin and supporting me morally. I am highly Thankful to Mr.
Akif razzaq for his technical assistance for constructing maps. May ALLAH bless them all with
success and happiness. At last but not the least I pay my cordial thanks to all those whose prayers
always surround me and who are nearest and precious to me, my Parents, my sister, and other
family members and all those who helped me ever in the life. All of my prayers and sacred
emotions are for them. May Allah bless them all in all the worlds (Amin).
Muhammad Ahsan Qureshi
3 DEDICATION IV
4 ACKNOWLEDGEMENT V
7 DETAILED TABLE OF CONTENTS VII
8 LIST OF TABLES XV
9 LIST OF FIGURES XIX
10 LIST OF APPENDICES XX
11 ABBREVIATION XXIV
12 ABSTRACT XXVI
2.3 Mandarins 8
2.4 Rootstocks 8
2.6 Effect of rootstock on vegetative performance of scion 10
2.6.1 Plant height/tree size 12
2.7 Effect of rootstocks on leaf mineral concentration 13
2.7.1 Nitrogen 16
2.8 Effect of rootstocks on tree physiology 19
2.8.1 Chlorophyll contents 20
2.8.2 Phytohormones concentration 21
2.8.3 Effect of rootstocks on carbohydrates concentration of citrus 22
2.9 Effect of rootstock on fruit production and quality 23
2.9.1 Production 24
2.9.2 Effect of rootstocks on various fruit quality attributes 26
2.9.2.1 Physical Quality 26
2.9.2.1.1 Fruit Size 26
2.9.2.1.3 Juice content 28
2.9.2.1.4 Seed number 29
2.9.2.2.1 Total soluble solids 30
2.9.2.2.2 Acidity (%) 31
3.1 Plant material and growing conditions 33
3.2 Experiment 1: Effect of various rootstocks on leaf mineral contents of
Kinnow mandarin 36
3.2.2 Parameters studied 36
3.2.3 Soil analysis 36
3.2.3.2 Electrical Conductivity of sample 36
3.2.3.3 Available nitrogen (ppm) 36
3.2.3.4 Available Phosphorus (ppm) 37
3.2.3.5 Exchangeable potassium and sodium (ppm) 37
3.2.5 Leaf sampling 37
3.2.5 Sample preparation 37
3.2.7 Wet digestion 38
3.2.8 Phosphorus determination 38
3.2.9 Potassium determination 39
3.2.10 Sodium estimation 39
3.2.11 Determination of Ca, Mg, Cu, Fe, Mn and Zn 39
3.2.12 Boron determination 41
3.2.13 Statistical analysis 41
3.3 Experiment 2: Effect of various rootstocks on tree growth and
physiology of Kinnow Mandarin 43
3.3.1 Experiment Layout and Design 43
3.3.2 Tree growth parameters 43
3.3.2.1 Rootstock girth (cm) 43
3.3.2.2 Scion girth (cm) 43
3.3.2.3 Tree height (m) 44
3.3.2.4 Leaf area (cm2) 44
3.3.2.5 Canopy volume (m3) 44
3.3.2.6 Tree shape 44
3.3.3 Physiological parameters of Kinnow 45
3.3.4 Photosynthetic pigments 45
3.3.5 Phytoharmones analysis 45
3.3.5.2 Chromatographic working conditions 46
3.3.5.3 Sample preparation 46
3.3.6 Carbohydrate analysis 46
3.3.6.2 Chromatographic working conditions 47
3.3.6.3 Sample preparation 47
3.3.6.4 Statistical analysis 47
XII
3.4 Experiment 3: Effect of various rootstocks on fruit production and
quality of Kinnow mandarin 49
3.4.1 Experiment Layout and Design 49
3.4.2 Reproductive behavior 49
3.4.2.1 Blooming intensity 49
3.4.2.4 Average fruit weight (g) 50
3.4.2.5 Total number of fruits 50
3.4.2.6 Yield per tree (Kg) 50
3.4.3 Fruit Quality Parameters 50
3.4.3.1 Physical quality attributes 50
3.4.3.1.1 Fruit diameter (mm) 50
3.4.3.1.2 Fruit height (mm) 50
3.4.3.1.3 Peel thickness (mm) 51
3.4.3.1.4 Seed count 51
3.4.3.1.6 Fruit shape 51
3.4.3.1.9 Density of oil glands 51
3.4.3.2 Biochemical quality attributes 51
3.4.3.2.1 Total Soluble Solids (ºBrix) 51
3.4.3.2.2 Titrable Acidity (%) 51
3.4.3.2.4 Sugar analysis 52
3.4.3.2.6 Reducing sugars 53
3.4.3.2.7 Non-reducing sugars 53
3.4.3.2.8 Total sugars 53
3.4.3.2.9 Determination of total phenolic contents (TPC) and total antioxidants 54
3.4.3.2.10 Total antioxidants 54
3.4.3.2.11 Total phenolic contents 56
3.4.3.2.12 Detection of glucose, fructose and sucrose in Kinnow juice by HPLC 57
3.4.3.2.12.1 Instruments and reagents 57
3.4.3.2.12.2 Chromatographic working conditions 57
3.4.3.2.12.3 Sample Preparation 57
3.4.4 Statistical analysis 57
CHAPTER 4 RESULTS 59
4.1 Experiment No. 1: Effect of various rootstocks on leaf mineral contents
of Kinnow mandarin 59
4.1.2.1 Boron (ppm) 68
4.1.2.2 Iron (ppm) 69
4.1.2.3 Zinc (ppm) 69
4.1.2.4 Manganese (ppm) 70
4.1.2.5 Copper (ppm) 71
4.1.3 Principle Component Analysis (PCA) for nutrients uptake of kinnow on
various rootstocks. 76
4.2 Experiment No. 2: Effect of various rootstocks growth of Kinnow
Mandarin 77
4.2.1 Morphological description of Kinnow tree on different rootstocks. 77
4.2.2 Effect of various rootstocks on vegetative growth of Kinnow mandarin 78
XIV
4.2.2.2 Scion girth 79
4.2.2.3 Tree height (m) 79
4.2.2.4 Canopy volume (m3) 80
4.2.2.5 Leaf area (cm2) 81
4.2.3 Effect of various rootstocks on physiology of Kinnow mandarin 88
4.2.3.1 Photosynthetic rate (μmol m-2 s-1) 88
4.2.3.2 Stomatal conductance (mmol m-2 s-1) 89
4.2.3.3 Transpiration rate (mmol m-2 s-1) 89
4.2.3.4 Sub stomatal CO2 (mmol m-2 s-1) 90
4.2.3.5 Water use efficiency 91
4.2.4 Effect of various rootstocks on photosynthetic pigments of kinnow
mandarin 95
4.2.4.3 Carotenoids 96
4.2.5 Effect of various rootstocks on endogenous plant hormones in Kinnow
mandarin 100
4.2.5.1 Indole acetic acid contents in rootstocks and scion 100
4.2.5.2 GA3 contents in rootstocks and scion 101
4.2.5.3 ABA contents in rootstocks and scion 102
4.2.5.4 Zeatin contents in rootstocks and scion 103
4.2.6 Distribution of carbohydrates in rootstocks and scion 107
4.2.6.1 Sucrose contents in rootstocks and scion 107
4.2.6.2 Fructose contents in rootstocks and scion 108
4.2.7 Principle Component Analysis (PCA) for growth of kinnow on various
rootstocks 111
4.3 Experiment No. 3 Effect of various rootstocks on fruit production and
quality of Kinnow mandarin 112
4.3.1 Fruit production 112
4.3.1.3 Fruit drop 114
4.3.1.4 Button drop (%) 114
4.3.1.5 June drop (%) 115
4.3.1.6 Preharvest drop (%) 116
4.3.1.8 Average fruit weight (g) 117
4.3.1.9 Total yield (kg) 117
4.3.2 Morphological description of citrus fruit 123
4.3.3 Fruit Quality 124
4.3.3.1 Physical quality 124
4.3.3.1.6 Seed count 127
4.3.3.2 Biochemical quality attributes of Kinnow mandarin 133
4.3.3.2.1 Total soluble solids (°Brix). 133
4.3.3.2.2 Titratable acidity (%) 133
4.3.3.2.4 Total sugars (%) 135
4.3.3.2.5 Reducing sugars (%) 135
4.3.3.2.6 Non-reducing sugars (%) 136
4.3.3.2.8 Total phenolic contents (mg GAE 100 g-1) 136
4.3.3.2.9 Juice pH 137
4.3.4.1 Sucrose 143
4.3.4.2 Fructose 143
4.3.4.3 Glucose 144
4.3.5 Principle component analysis (PCA) for yield and fruit quality of
Kinnow on various rootstocks 146
CHAPTER 5 DISCUSION 147
5.1 Effect of various rootstocks on leaf mineral contents of Kinnow
mandarin 147
5.2 Effect of various rootstocks on tree growth of Kinnow 150
5.3 Effect of various rootstocks on fruit production and quality of Kinnow
Mandarin 153
3.1 General characteristics of rootstocks evaluated for Kinnow mandarin 35
3.2 Working conditions of Atomic Absorption Spectrophotometer for the
determination of Ca, Mg, Fe, Mn, Zn and Cu 40
4.1 Effect of rootstocks on nitrogen (%) uptake in Kinnow mandarin (Mean ±
SE). 65
4.2 Effect of rootstocks on phosphorus (%) uptake in Kinnow mandarin (Mean ±
SE) 65
4.3 Effect of rootstocks on potassium (%) uptake in Kinnow mandarin (Mean ±
SE) 66
4.4 Effect of rootstocks on calcium (%) uptake in Kinnow mandarin (Mean ± SE) 66
4.5 Effect of rootstocks on magnesium (%) uptake in Kinnow mandarin (Mean ±
SE) 67
4.6 Effect of rootstocks sodium (%) uptake in Kinnow mandarin (Mean ± SE) 67
4.7 Effect of rootstocks on boron (ppm) uptake in Kinnow mandarin (Mean ± SE) 73
4.8 Effect of rootstocks on iron (ppm) uptake in Kinnow mandarin (Mean ± SE). 73
4.9 Effect of rootstocks on zinc (ppm) uptake in Kinnow mandarin (Mean ± SE). 74
4.10 Effect of rootstocks on manganese (ppm) uptake in Kinnow mandarin (Mean
± SE). 74
4.11 Effect of rootstocks on copper (ppm) uptake in Kinnow mandarin (Mean ±
SE) 75
4.12 Morphological characteristics of Kinnow mandarin 77
4.13 Effect of rootstocks on rootstock girth (cm) of Kinnow mandarin (Mean ± SE) 83
4.14 Overall increment in rootstock girth grafted with Kinnow mandarin 83
4.15 Effect of rootstocks on scion girth (cm) of Kinnow mandarin (Mean ± SE) 84
4.16 Overall increment in scion girth grafted on different rootstocks 84
XVIII
4.17 Effect of rootstocks on tree height (m) of Kinnow mandarin (Mean ± SE) 85
4.18 Overall increment in tree height grafted on different rootstocks 85
4.19 Effect of rootstocks on canopy volume (m3) of Kinnow mandarin (Mean ±
SE) 86
4.20 Overall increment in canopy volume grafted on different rootstocks 86
4.21 Effect of rootstocks on leaf area (cm2) of Kinnow mandarin (Mean ± SE) 87
4.22 Effect of rootstocks on photosynthetic rate (μmol m-2s-1) of Kinnow mandarin
(Mean ± SE) 92
4.23 Effect of rootstocks on stomatal conductance (mmol m-2s-1) of Kinnow
mandarin (Mean ± SE). 92
4.24 Effect of rootstocks on transpiration rate (mmol m-2s-1) of Kinnow mandarin
(Mean ± SE). 93
4.25 Effect of rootstocks on Sub stomatal CO2 (mmol m-2 s-1) of Kinnow mandarin
(Mean ± SE). 93
4.26 Effect of rootstocks on water use efficiency of Kinnow mandarin (Mean ±
SE). 94
4.27 Effect of rootstocks on chlorophyll a (mg g-1 FW) contents of Kinnow
mandarin (Mean ± SE). 98
4.28 Effect of rootstocks on chlorophyll b (mg g-1 FW) contents of Kinnow
mandarin (Mean ± SE). 98
4.29 Effect of rootstocks on carotenoids (mg g-1 FW) contents of Kinnow mandarin
(Mean ± SE).). 99
4.30 Status of indole acetic acid (ng.g-1 FW) in various rootstocks and kinnow
scion 105
4.31 Status of gibberelic acid (ng.g-1 FW) in various rootstocks and kinnow scion 105
4.32 Status of Abscisic acid (ng.g-1 FW) in various rootstocks and kinnow scion 106
4.33 Status of zeatin (ng.g-1 FW) in various rootstocks and kinnow scion 106
4.34 Status of sucrose (%) in various rootstocks and kinnow scion. 110
XIX
4.35 Status of fructose (%) in various rootstocks and kinnow scion. 110
4.36 Effect of rootstocks on blooming intensity of Kinnow mandarin (Mean ± SE). 119
4.37 Effect of rootstocks on fruit set (%) of Kinnow mandarin (Mean ± SE). 119
4.38 Effect of rootstocks on button drop (%) of Kinnow mandarin (Mean ± SE). 120
4.39 Effect of rootstocks on June drop (%) of Kinnow mandarin (Mean ± SE). 120
4.40 Effect of rootstocks on preharvest drop (%) of Kinnow mandarin (Mean ±
SE). 121
4.41
Effect of rootstocks on number of fruits of Kinnow mandarin (Mean ± SE). 121
4.42 Effect of rootstocks on fruit weight (g) of Kinnow mandarin (Mean ± SE) 122
4.43 Effect of rootstocks on yield/tree (Kg) of Kinnow mandarin (Mean ± SE). 122
4.44 Morphological description Kinnow fruits on different rootstocks 123
4.45 Effect of rootstocks on fruit diameter (mm) of Kinnow mandarin (Mean ±
SE). 129
4.46 Effect of rootstocks on fruit height (mm) of Kinnow mandarin (Mean ± SE). 129
4.47 Effect of rootstocks on rag weight (g) of Kinnow mandarin (Mean ± SE). 130
4.48 Effect of rootstocks on peel weight (g) of Kinnow mandarin (Mean ± SE) 130
4.49 Effect of rootstocks on peel thickness (mm) of Kinnow mandarin (Mean ±
SE). 131
4.50 Effect of rootstocks on number of seeds of Kinnow mandarin (Mean ± SE). 131
4.51 Effect of rootstocks on seed weight (g) of Kinnow mandarin (Mean ± SE). 132
4.52 Effect of rootstocks on number of segments of Kinnow mandarin (Mean ±
SE). 132
4.53 Effect of rootstocks on TSS (°Brix) of Kinnow mandarin (Mean ± SE). 138
4.54 Effect of rootstocks on TA (%) of Kinnow mandarin (Mean ± SE). 138
4.55 Effect of rootstocks on vitamin C (mg/100ml) content Kinnow mandarin
(Mean ± SE). 139
XX
4.56 Effect of rootstocks on total Sugars (%) of Kinnow mandarin (Mean ± SE). 139
4.57 Effect of rootstocks on reducing Sugars (%) of Kinnow mandarin (Mean ±
SE). 140
4.58 Effect of rootstocks on non-reducing Sugars (%) of Kinnow mandarin (Mean
± SE). 140
4.59 Effect of rootstocks on total antioxidant activity (%inhibition) of Kinnow
mandarin (Mean ± SE). 141
4.60 Effect of rootstocks on total phenolic content (mg GAE 100 g-1) of Kinnow
mandarin (Mean ± SE). 141
4.61 Effect of rootstocks on juice pH (mg GAE 100 g-1) of Kinnow mandarin
(Mean ± SE). 142
4.62 Effect of rootstocks on sugar contents (g/L) in Kinnow juice. 145
XXI
2.2 Citrus growing areas of Pakistan 6
2.3 Province wise citrus production in Pakistan 7
3.1 Aerial image of experimental site 34
3.2 Pictorial Description of nutrient analysis 42
3.3 Pictorial description of vegetative and physiological analysis 48
3.4 Flow chart for extraction of total antioxidants and TPC in juice of
‘Kinnow’ fruit 54
3.5 Flow chart for determination of total antioxidants in juice of ‘Kinnow’
fruit 55
3.6 Flow chart for determination of TPC in juice of ‘Kinnow’ fruit. 56
3.7 Pictorial description of yield and quality analysis 58
4.1 PCA biplot for rootstocks and variables (Experiment 1) 76
4.2 PCA biplot for rootstocks and variables (Experiment 2) 111
4.3 PCA biplot for rootstocks and variables (Experiment 3) 146
XXII
No. Title
Appendix 1 Analysis of variance table for N, P and K
Appendix 2 Analysis of variance table for Ca, Mg and Na
Appendix 3 Analysis of variance table for B, Fe and Zn
Appendix 4 Analysis of variance table for Mn and Cu
Appendix 5 Analysis of variance table for Rootstock girth, Scion girth, Tree height and
Canopy volume
Appendix 6 Analysis of variance table for leaf area, Leaf length and Leaf width
Appendix 7 Analysis of variance table for Photosynthetic activity (A), Transpiration
rate (E) and Stomatal conductance (g)
Appendix 8 Analysis of variance table for Sub stomatal CO2 (Ci) and Water use
efficiency
Appendix 9 Analysis of variance table for chlorophyll a, Chlorophyll b and carotenoids
Appendix 10 Analysis of variance table for IAA and GA3
Appendix 11 Analysis of variance table for ABA and ZT
Appendix 12 Analysis of variance table for carbohydrates
Appendix 13 Analysis of variance table for intensity of bloom and fruit set percentage
Appendix 14 Analysis of variance table for Button drop, June drop and Pre harvest drop
Appendix 15
Analysis of variance table for Yield parameters
Appendix 16 Analysis of variance table for Fruit diameter and Fruit height
Appendix 17 Analysis of variance table for Rag weight and Peel weight
Appendix 18 Analysis of variance table for Peel thickness and Seed count
XXIII
Appendix 19 Analysis of variance table for Seed weight and Number of segments
Appendix 20 Analysis of variance table for TSS and TA
Appendix 21 Analysis of variance table for Total, Reducing and Non-reducing sugars
Appendix 22 Analysis of variance table for Total antioxidants and Total phenolic
contents
Appendix 23 Analysis of variance table for Vitamin C and Juice pH
Appendix 24 Analysis of variance table for Sucrose, Fructose and Glucose
Appendix 25 Chromatogram for phytohormones detection in Kinnow on Rough lemon
Appendix 26 Chromatogram for phytohormones detection in Rough lemon rootstock
Appendix 27 Chromatogram for phytohormones detection in Kinnow on Cox mandarin
Appendix 28 Chromatogram for phytohormones detection in Cox mandarin rootstock
Appendix 29 Chromatogram for phytohormones detection in Kinnow on Fraser hybrid
Appendix 30 Chromatogram for phytohormones detection in Fraser hybrid rootstock
Appendix 31 Chromatogram for phytohormones detection in Kinnow on Troyer
Citrange
Appendix 33 Chromatogram for phytohormones detection in Kinnow on Cleopatra
mandarin
rootstock
XXIV
Appendix 35 Chromatogram for phytohormones detection in Kinnow on Poncirus
trifoliata
rootstock
Appendix 37 Chromatogram for phytohormones detection in Kinnow on Benton
Appendix 38 Chromatogram for phytohormones detection in Benton rootstock
Appendix 39 Chromatogram for phytohormones detection in Kinnow on C-35
Appendix 40 Chromatogram for phytohormones detection in C-35 rootstock
Appendix 41 Chromatogram for phytohormones detection in Kinnow on Carrizo citrange
Appendix 42 Chromatogram for phytohormones detection in Carrizo citrange rootstock
Appendix 43 Chromatogram for carbohydrates detection in Kinnow on Rough lemon
Appendix 44 Chromatogram for phytohormones detection in Rough lemon rootstock
Appendix 45 Chromatogram for carbohydrates detection in Kinnow on Cox mandarin
Appendix 46 Chromatogram for phytohormones detection in Cox mandarin rootstock
Appendix 47 Chromatogram for carbohydrates detection in Kinnow on Fraser hybrid
Appendix 48 Chromatogram for phytohormones detection in Fraser hybrid rootstock
Appendix 49 Chromatogram for carbohydrates detection in Kinnow on Troyer Citrange
Appendix 50 Chromatogram for phytohormones detection in Troyer Citrange rootstock
XXV
Appendix 51 Chromatogram for carbohydrates detection in Kinnow on Cleopatra
mandarin
rootstock
Appendix 53 Chromatogram for carbohydrates detection in Kinnow on Poncirus
trifoliata
rootstock
Appendix 55 Chromatogram for carbohydrates detection in Kinnow on Benton
Appendix 56 Chromatogram for phytohormones detection in Benton rootstock
Appendix 57 Chromatogram for carbohydrates detection in Kinnow on C-35
Appendix 58 Chromatogram for phytohormones detection in C-35 rootstock
Appendix 59 Chromatogram for carbohydrates in Kinnow on Carrizo citrange
Appendix 60 Chromatogram for carbohydrates in Carrizo citrange rootstock
Appendix 61 Chromatogram for Detection of Sugars in juice of Rough lemon
Appendix 62 Chromatogram for Detection sugars in juice of Cox mandarin
Appendix 63 Chromatogram for Detection sugars in juice of Fraser hybrid
Appendix 64 Chromatogram for Detection sugars in juice of Troyer citrange
Appendix 65 Chromatogram for Detection sugars in juice of Cleopatra mandarin
Appendix 66 Chromatogram for Detection sugars in juice of Poncirus Trifoliata
Appendix 67 Chromatogram for Detection sugars in juice of Benton
Appendix 68 Chromatogram for Detection sugars in juice of C-35
Appendix 69 Chromatogram for Detection sugars in juice of Carrizo citrange
XXVI
ABBREVIATIONS
MT Metric ton
GOP Government of Pakistan
CTV Citrus Tristeza virus
IRGA Infrared gas analyzer
IAA Indole acetic acid
LSD Least significance test
TSS Total soluble solids
XXVIII
Abstract
Citrus industry is very important to the economy of Pakistan. Citrus is commonly grown on
rootstocks, which effects on more than twenty parameters of scion cultivars. Modern world is
developing and adopting new rootstocks for commercial citrus production by applying
conventional and biotechnological breeding tools and have developed many high yielding
rootstocks which are tolerant/ resistant to biotic and abiotic stresses. In Pakistan, citrus
industry is dependent on two rootstocks; Rough lemon in Punjab and Sour orange in Khyber
Pakhtunkhwa provinces. Problems faced by these two rootstocks results in low production,
disease infestation and short orchard life. To address these short falls, present research was
designed to evaluate eight new rootstocks for their effect on vegetative and reproductive
characters of ‘Kinnow mandarin’, which could replace/add to traditionally used rootstocks in
Pakistan to overcome gaps in citriculture industry. Present research was carried out at
Postgraduate Agricultural Research Station (PARS) University of agriculture Faisalabad
during 2017-18. Kinnow mandarin grafted on nine different rootstocks i.e. Rough lemon,
Cox mandarin, Fraser hybrid, Troyer citrange, Cleopatra mandarin, Poncirus trifoliata,
Benton, C-35 and Carrizo citrange, treating Rough lemon as control. Trees were planted
according to square system of orchard layout. Performance of rootstocks was evaluated based
on nutrient uptake, growth and fruit production. First experiment was to evaluate the effect of
different rootstocks on macro and micronutrients uptake of Kinnow mandarin. Poncirus
trifoliata showed the superior behavior by having maximum macronutrients followed by
Fraser hybrid, while Troyer citrange showed poor uptake. Second experiment was focused on
effect of rootstocks on tree growth, vigor and physiology of Kinnow mandarin, including leaf
gas exchange, photosynthetic pigments, carbohydrates and endogenous plant hormones in
rootstock and scion parts. Poncirus trifoliata rootstock was excellent for vegetative
characters of Kinnow tree and Troyer citrange rootstock was the poorest. Concentration of
indole acetic acid, gibberellic acid and zeatin in rootstocks and scion were high in Poncirus
trifoliata and low in Troyer citrange. High concentration of abscisic acid was recorded in
Troyer citrange. To record the compatibility of rootstock regarding carbohydrates
distribution, Poncirus trifoliata excelled again followed by Fraser hybrid. In last experiment
effect of rootstocks on production and quality of Kinnow mandarin was studied. Maximum
fruit yield and other fruit production parameters were recorded on Poncirus trifoliata
followed by Fraser hybrid. Minimum yield was recorded on Troyer citrange rootstock. Fruit
quality parameters were the best on Fraser hybrid rootstock. It is concluded from these
studies that Poncirus trifoliata and Fraser hybrid were best performing rootstocks in relation
to Kinnow. Poor performance of citrange rootstocks i.e., Troyer citrange, Benton citrange
and Carrizo citrange was recorded in relation to Kinnow. Poncirus trifoliata and Fraser
hybrid may further need to be evaluated against other biotic and abiotic stresses and could
prove potential rootstocks for citrus industry of Pakistan besides Rough lemon and Sour
orange.
1
CHAPTER 1 INTRODUCTION
Citrus (Citrus sinensis L.) holds the key position in world fruit industry, being grown
on a large scale in tropical and subtropical regions around the globe. Major production area
for citrus is concentrated between 40° North and 40° south of equator. Citrus belongs to family
Rutaceae, having sub family Aurantioideae and further represented by 28 genera in the tribe
citreae (Swingle and Reecce 1967). While talking about the commercial cultivation of citrus,
it is being produced in 53 countries with the production of 137.8 million MT. On the basis of
the production, China tops with 29.65 million metric tonnes followed by Brazil with 18.96
million metric tonnes and USA is third with 10.01 million metric tonnes (FAO, 2019).
Citrus holds the key position in horticulture industry of Pakistan. Citrus is being
significantly grown in many areas of Punjab i.e. Sargodha, Faisalabad and Toba Tek Singh.
These districts of central and upper Punjab contributes the maximum share in total citrus
production of Pakistan. The share of lower Punjab and other provinces of Pakistan is low in
production. In citrus global scenario, Pakistan ranks 7th according to area and 13th according to
production. While comparing with leading citrus producing nations like Brazil, USA, China
and Spain, citrus production of Pakistan is far behind and increasing at an average annual rate
of only 5%. Brazil holds the 35% share in total citrus production of world while share of
Pakistan is only 1.46%. In Pakistan, the area under citrus growing is about 192832 hectares
and total annual production is 2395550 tonnes (FAO, 2019). The world citrus industry is
dominated by sweet orange with 61.18 per cent contribution followed mandarin with a share
of 22.12%, lime and lemon with a share of 11.4 % and rest of 5.5 % is contributed by grapefruit
and other cultivars of citrus family. Mandarin fruit are relatively small with a tender peel and
do not store or ship well. Trees tend to over-bear, which contributes to biennial bearing. All
the important phenomenon in a citrus tree such as leaf mineral contents, vegetative
performance, bearing habit and reproductive behavior can be significantly influenced by
different rootstocks (Castle, 1980, 1987)
Among mandarins, Kinnow, the first generation hybrid between King (Citrus nobilis
Lour) and Willow leaf (Citrus deliciosa Tenora), was developed by H.B. Frost at the
University of California, Citrus Experiment Station, Riverside, Davis (USA) in 1915.
Although, it was released for commercial cultivation during the year 1935. History reveals
that it was introduced for the first time in subcontinent in 1943-44 at Horticulture Fruit Garden
2
Sq. # 9, Punjab Agricultural College and Research Institute Lyallpur, now University of
Agriculture, Faisalabad. Since its introduction, Kinnow has become the most favored cultivar
choice among citrus growers in Pakistan, because it has adapted very well under arid and
semi-arid climatic conditions where other citrus varieties are not performing well.
Kinnow mandarin is considered as trademark product of Pakistan. This distinction of
Kinnow is due to its magnificent aroma, premium taste, high juice contents and nutritional
profile of Kinnow i.e. high vitamin C contents, rich in sugars and antioxidants (Memon, 2014).
Pakistan contributes 2.5 % to world’s mandarin production by producing better quality of
Kinnow (Divya, 2014). Fruit vendors in foreign countries such as, Indonesia, Philippine, Hong
Kong, Europe, Canada, Sri Lanka and Bangladesh prefer Kinnow mandarin from orchards of
Pakistan (Siddiqui, 2015). Kinnow production in Pakistan has not reached to its maximum
production potential besides of being the commercial fruit crop of Pakistan. There is an
enormous production gap between average production of Pakistan and other developing
countries. Pakistan is getting 9-10 tons per hectare while other developing countries are
producing 20-25 tons of Kinnow per hectare (Anonymous, 2010). This was the main reason
for decline in area under citrus production in last five years (GOP, 2014). Besides this, other
factors are involved in citrus decline production. These factors include faulty and diseased
plant material, unavailability of proper rootstock, climate change, imbalanced nutrient, poor
management practices, and several biotic and abiotic stresses. (Nasir et al., 2014; Yasin et al.,
2001; Ahmad et al., 2009; Ibrahim et al., 2007; Tariq et al., 2007; Ahmad et al., 2004;).
Citrus trees propagated by seed are vigorous, upright growers, extremely thorny and
have long juvenile period. Citrus species which are grown by seeds are mostly unable to
possess resistance against hot and cold climate, soil borne diseases, abiotic stresses such as
salinity, heat and drought and other quality traits which are required for survival of a plant
(Khan et al., 2015). Citrus is generally propagated by budding and grafting, to take the
maximum advantage of rootstock’s influence on scion cultivars. Rootstocks are selected with
the objective to increase the performance of soil in terms of vegetative and reproductive
quality. Different rootstocks vary in their adoptability which varies from soil to soil, climate
to climate and even it varies from scion to scion (Iftikhar et al., 2009).
Rootstocks play an important role for success and failure in citrus industry. Out of
various factors responsible for citrus decline, rootstock is most important contributory factor.
3
There are almost twenty horticultural traits such as leaf nutrient status, tree vigor, rooting
characteristics, tolerance to low or high temperature, disease resistance, productivity and fruit
quality which are being controlled and manipulated by different rootstocks (Castle, 1987).
Because of advantage of enhancing fruit yield, quality and resistance against different biotic
and abiotic stresses the utilization of rootstock in very important (La Rosa, 2012). Ability of
a plant to absorb water and nutrients from the soil is significantly influenced and can be
improved by different rootstocks. Rootstocks have the capacity to manipulate the pattern of
canopy development and stem girth and other physiological processes such as such as
photosynthetic activity, stomatal conductance and transpiration rate (Richardson et al., 2003).
It is important to understand the hormonal interaction between rootstock ad scion and how they
interact. Rootstocks has a significant role in manipulating the concentrations of auxins,
gibberellins and cytokinins in scion portion. Concentration of zeatin and indole acetic acid in
scion portion is significantly controlled by different rootstocks. In peach rootstocks, a positive
interaction between tree vigor and zeatin concentration and negative interaction between IAA
and tree vigor was reported by Sorce et al. 2002. The concentrations of phytoharmones
manipulated by different rootstocks, influence the tree vigor and the changes in tree vigor
directly influence the several other parameters including canopy volume, photosynthetic
activity, chlorophyll contents and stomatal conductance. All of these factors tend to manipulate
the overall yield of scion cultivar grafted on different rootstocks.
Internal quality parameters of fruits such as juice content, color of flesh and peel, total
soluble solids, titrable acidity, juice pH are also affected by rootstocks (Wutscher, 1997). Scion
cultivars differ in fruit quality, nutrients accumulation, tree growth and physiology when
grown on diverse rootstocks, therefore, selection of rootstock must be done with utmost care
before establishing an orchard. Growth parameters of scion cultivar i.e. mineral contents, and
tree physiology differs when they are grafted on different rootstocks even grown on same soil.
(Bassal, 2009). Despite of having resistance against biotic an abiotic stresses, a successful
rootstock should be compatible between scion and rootstock (Campeanu et al., 2009). Growers
can use a suitable rootstocks to control the vigor and production of orchard trees (Castle et al.,
1988). Choice of rootstock is important aspect in fruit crops especially in citrus because of
varying behavior of different scion cultivars of citrus on different rootstocks. (Bergmann,
1992).
4
‘Rough lemon’ and ‘Sour Orange’ are the major rootstocks which are currently being
used in Pakistan. The use of ‘Carrizo citrange’ in Mediterranean regions had been increased
over past decades due to its benefits like increased water and nutrient uptake from soil
(Srivastav et al., 2005; Kaplankran and Tuzcu, 1993). In past, various rootstocks had been
recommended and reported for Kinnow which are vigorous and dwarfing in nature such as
Troyer citrange, Karna Khatta and Sohsarkar (Goswami et al., 2001). There are many other
useful rootstocks which are still unexplored therefore, it is the need of time to evaluate other
rootstocks in relation to commercial citrus cultivar of Pakistan i.e. ‘Kinnow’ for its enhanced
vigor and better yield potential
There is an absolute need of new rootstocks for Kinnow because of monopolized
cultivation of Kinnow on a single rootstock. Modern world is adopting new rootstocks which
are resistant to biotic (diseases, insect pests) and abiotic (heat, cold, salt stress etc.) stresses for
commercial citrus production by applying conventional and biotechnological breeding tools.
But Pakistan’s citrus industry is still far behind in this scenario, depending on just two
rootstocks. There are some merits and demerits of these rootstocks as well. On one side ‘Rough
lemon’ is resistant to CTV, while on the other hand it is susceptible to phytophthora, water
logging and salinity; likewise ‘Sour Orange’ is resistant to nematodes while it is susceptible to
CTV and quick decline (Toplu et al., 2012). This is one of the major reasons that citrus
production of Pakistan is very low.
In the light of above discussion following gaps exists in Pakistan’s citrus industry
• Dependence on one or two rootstocks
• Little exploitation and documentation of usefulness of new rootstocks
To address these short falls, present research was designed to evaluate eight new
rootstocks for their effect on vegetative and reproductive characters of ‘Kinnow Mandarin’
which could replace/add to traditionally used rootstocks in Pakistan to overcome gaps in
citruculture industry of Pakistan.
CHAPTER 2 REVIEW OF LITERATURE
2.1 Citrus introduction and origin
The position of citrus fruit to agriculture and economy of the world is established by
large-scale production and wide cultivation. Citrus is an important member of the family
Rutaceae and its several species of citrus plant are supposed to be indigenous to tropical and
sub-tropical regions of Asia and Malaya archipelago (Hooker, 1872). In subtropical
Mediterranean climate specifically and all over the world generally, there are various less
familiar species of the genus Citrus which are being cultivated there since antiquity. Acclaimed
bioactive value, delicious taste and attractive appearance are the major reasons or the
popularity of citrus fruits (Liu et al., 2015). Talking about worldwide production of citrus
China stands at top followed by Brazil and USA. According to United States Department of
Agriculture report, in 2016, major exporters of citrus fruits (oranges, mandarins tangerines and
grape fruits) were South Africa (1,867 thousand tons), Egypt (1200 thousand tons), China (913
thousand tons), United States (872 thousand metric tons) (USDA, 2019).
Fig. 2.1: Worldwide citrus production (FAO, 2019)
6
In Pakistan, 90% of the total citrus is produced in Punjab Province. Sargodha district
in Punjab province is considered as hub for citrus production by producing 70 % of total citrus
production in Punjab (Ashraf et al., 2012). Citrus is being cultivated in other districts of Punjab
such as Toba Tek Singh, Faisalabad, Lahore and Gujranwala. Noshera, Peshawar and Mardan
are the major citrus growing areas in Khyber Pakhtunkhuwa province, while in Sindh province
citrus production is concentrated in Nawabshah, Khairpur and Sukkur. Baluchistan province
has minimal share in overall citrus production. Mekran and Sibbi districts has some potential
for citrus production. Kinnow mandarin and Feutrell Early are the major citrus varieties which
are grown in Punjab province and accounts for 86 % of the total citrus growing area (GOP,
2019).
7
Fig. 2.3 Province wise citrus production in Pakistan (Provincial Crop Reporting Service
Centers, 2018-2019)
2.2 Nutritional perspectives of citrus
Citrus is rich resource of many nutritional constituents which are very important for
normal human health. Vitamins, minerals, carbohydrates and antioxidants are present in
significantly higher amounts in citrus. Citrus contributes towards a healthy normal human life
by controlling several fatal diseases such as liver cancer, problems of lungs, skin irregularities,
and some heart issues (Kaplankiran et al., 1995). Citrus is one of the most attractive fruit
because of its fragrance and nutritional importance. Besides having higher sugar contents in
the range of 3-4 %, citrus is the amicably rich source of Vitamin C with high antioxidant
activity (Moeen et al., 2001). Peel of the fruit is equally important and nutritious as the pulp
of citrus fruit. High contents of pectin are present in peel of citrus. Moreover citrus peel is
utilized in making and preparation of many value added products of citrus such as jams, jellies
and marmalades. Many pharmaceutical industries also use citrus peel in formation of several
8
drugs and antibiotics. Presence of organic acids, phenolics and antioxidants in varying
quantities in different cultivars of citrus has a significant effect on fruit quality and organoleptic
characteristics of fruits (Bertini et al., 2006).
2.3 Mandarins
Mandarin fruit are relatively small with a tender peel and do not store or ship well.
Trees tend to over-bear, which contributes to biennial bearing. Mandarin and mandarin hybrid
cultivars are treated as specialty fruit and are only a small part of the citrus acreage in the
United States. Nevertheless, the demand for mandarin fruit, particularly ‘Fairchild’ grown in
Arizona, is increasing (Arizona Agricultural Statistics Service, 1988). By producing 2.1
million tons of mandarins annually Pakistan stands at 6th position globally in the list of top
mandarin producing countries.
2.4 Rootstocks
In the pursuit of importance of rootstocks, citrus cultivars are propagated asexually
through grafting and budding on specific rootstocks for attaining the superior performance of
scion cultivars in specific agro climatic regions (Forner-Girner et al., 2014). Rootstocks play
very important role in Citriculture industry and decide success or failure of citrus cultivation.
The rootstocks experiment have been performed out in different citrus growing countries from
time to time to achieve one or several varied ends such as tree longevity, better scion vigour,
insect-pest resistance, adaptability to a specific agro-climatic region, improved fruit quality
and higher yield. Rootstocks, however, have their own merits and demerits for example sweet
orange, grapefruit, mandarin and lemon on rough lemon rootstock are large, extremely
vigorous and productive among most rootstocks worldwide. However, scion cultivars on rough
lemon are very susceptible to frost damage (Yelenosky and Young, 1977). Various scientists
have reported the significant influence of rootstocks on leaf mineral contents, tree vigor,
bearing habit, yield and fruit quality of mandarins. (Castle, 1980, 1987; Castle and Phillips,
1977). Sour orange, although is an excellent rootstock for areas free of citrus tristeza virus
(CTV) but its susceptibility to CTV, particularly of sweet orange on sour orange has greatly
restricted its use. Jatti Khatti has been reported to be an ideal rootstock for Kinnow mandarin
but it is susceptible to Phytopthora (Savita et al., 2012) and salinity (Kakade et al., 2014)
besides its vigorous behaviour. Genetic potential of selected rootstocks is expressed in terms
of plant vigour, modify architecture of plants, enhance nutrient and water use, modify
9
impart resistance/tolerance to various biotic and abiotic stresses. Climate change on the other
hand is projected to have significant impacts on conditions affecting citrus industry. To
circumvent such crisis and to enhance citrus fruit industry, particularly, Kinnow mandarin
which is the future of citrus industry in India needs responsive rootstock(s) for enhanced
productivity and tolerance to various biotic and abiotic stresses. The review deals with the
different impact of rootstocks on scion cultivar Kinnow and citrus in particular.
2.5 Rootstock Scion Interaction
Under a specific and uniform set of climatic and soil conditions, citrus rootstocks tend
to vary in their compatibility with a specific scion cultivar. A lot of trials have been conducted
to figure out a specific rootstock for commercial scion cultivars of citrus which could address
the all aspects of tree in a positive manner (Ahmad, 1962; Ismail et al., 1965; Ranjit et al.,
1978; Gowda et al., 1982). For addressing the various shortcomings of citrus i.e. problems
related to soil, biotic stresses and abiotic stresses, usage of rootstocks has become mandatory.
Moreover, rootstocks can also help the growers to meet the demands which are made by
consumers such as enhanced fruit quality, early fruit maturity and short juvenile phase of tree
(Tuzcu, 1978; Davies and Albrigo, 1994). In the global scenario Common Sour Orange is used
as major rootstock but in recent years, some other rootstocks such as ‘Trifoliate’, ‘Troyer
citrange’ and ‘Carrizo citrange’ have also become popular among the citrus growers. There is
an increased usage of ‘Poncirus trifoliata’ and ‘Carrizo’ citrange rootstocks specifically in
mandarin orchards because of hardy nature of these rootstocks and enhanced degree of
compatibility with mandarins (Tuzcu et al., 1998). The reason for moving on from sour orange
to other alternative rootstocks is its less degree of tolerance to Citrus trizteza virus (Tuzcu,
1978; Davies and Albrigo, 1994). It has been demonstrated and described by many researchers
that there is complex relation between rootstocks and scion cultivars which manipulates the
various aspects of citrus tree such as tree vigor, earliness in productivity, yield quality (Tuzcu
et al., 1998; Bowman, 1998; Tsakelidou et al., 2002; Georgiou, 2002; Stenzel et al., 2003;
Romero et al., 2006; Filho et al., 2007). The impact of different rootstocks on overall yield,
physico-chemical quality of fruit and tree size of 'Valencia' orange in Florida citrus orchards
revealed that ‘Sun Chu Sha’ and ‘Cleopatra mandarin’ undergoes best performance over other
10
rootstocks. Speaking of tree survival and fruit productivity of individual trees, the performance
of ‘Cleopatra mandarins’ was particularly good. This rootstock is not used as a commercial
rootstock (Hutchison and Heran, 1992).
2.6 Effect of rootstock on vegetative performance of scion
The rootstocks have significant influence overall growth of tree including vegetative
growth and reproductive growth. Vigor of scion cultivar and its resistance to different biotic
and biotic stresses is manipulated by rootstocks (Continella et al., 2018). All the major
vegetative parameters i.e. tree height, stem girth, leaf area and canopy volume are affected by
rootstocks. In Italy, a trial was conducted to check the effect of different rootstocks and on
tree growth and physiology. 'Bitters' and 'Furr' rootstocks were promising because of their
positive influence on fruit yield and quality also on agronomic parameters of citrus fruits.
These promising rootstocks were introduced to citrus industry of Italy (Filho et al., 2007).
Similiarly, in another experiment effect of different rootstocks on tree growth and yield of
lemon cultivars was investigated, ‘Rough Lemon’ and ‘RLC-4’ rootstocks gave maximum tree
height and canopy; while, ‘Billikichlli’ and ‘RLC-4’ rootstocks gave maximum trunk cross
sectional area (Dubey and Sharma, 2016). ‘Sour Orange’ rootstock gave best results for the
vegetative growth parameters i.e. canopy and diameter, tree volume, disk tree circumference.
Maximum tree height was obtained on ‘Carrizo citrange’ rootstock, while the trees that were
grafted on ‘Cleopatra mandarin’ rootstock were the shortest in the height (Bassal, 2009).
‘Hamlin’ was grafted on ‘Carrizo citrange’ and ‘Cleopatra mandarin’ rootstocks to observe the
effect of these rootstocks on citrus nursery plant growth. It was the rootstock that had a
significant effect on the sprout of scion cultivar. Sprout numbers and duration, both factors are
influenced by rootstocks (Williamson, 1991). Rootstock have marked effect on plant size,
shape, vigour, growth, season of maturity etc. Effect of rootstock on scion vigour has been well
documented (Castle, 1987; Roose et al., 1989; Fallahi and Rodney, 1992; Wutscher and
Bowman, 1999; Richardson et al., 2003; Forner-Giner et al., 2009; Castle et al., 2010).
In the first citrus rootstock study conducted in Punjab (Brown, 1920) mandarin was
found to make vigorous growth on Rough lemon, medium on sweet lime and was
unsatisfactory on the sour orange and citron rootstocks. On the basis of extensive rootstock
trials conducted at Abohar, Sharma et al. (2002) reported that trees of Campabell Valencia
sweet orange on Carrizo citrange rootstock were most vigorous whereas, those on Kharna
11
Khatta (Sour orange) rootstock were the poorest in growth. Trees of Kinnow mandarin in
Abohar, Punjab gave a better performance on Jatti Khatti (Rough lemon) closely followed by
Karun Jamir and the minimum growth was on Pectinifera rootstock (Sharma et al., 2002).
Similarly, Stenzel et al. (2003) reported that out of seven rootstocks tried in Londrina, Brazil
for Ponkan mandarin, Sunki mandarin on Volkamer lemon showed significant lower plant
height than other rootstocks. Likewise, Castle et al. (2010) observed the largest trees of
Valencia sweet orange on Volkamer lemon and the shortest trees on Swingle citrumelo among
twelve rootstocks evaluated. The trees of Sunbrust mandarin in Piracicaba, Brazil gave better
performance on Orlando tangelo than on Rangpur lime, Swingle citrumelo and Cleoptara
mandarin (Filho et al., 2007). Similarly, Bassal (2009) working in Ismailia, Egypt reported that
trees of Marisol clementine resulted in maximum plant height on Carrizo citrrange and Swingle
citrumelo whereas, the lowest was on Cleoptara mandarin and sour orange among the four
rootstocks evaluated. Kinnow had a better growth on Rough lemon in comparison to Cleopatra,
Rangpur lime, Troyer and Trifoliate orange as per report of Srivastava and Sopaiah (1976).
Likewise, Levy and Shaked (1980) working in Israel reported the largest canopy development
of cultivar Eureka and Villafrance on Alemow and Volkameriana in comparison with Rough
lemon and Rangpur lime.
Tayde et al. (1995) investigated the influence of nine various rootstocks on Kinnow
under Akola conditions of Maharashtra, India. Best performance of Kinnow was recorded on
Marmalade orange rootstock. Sharma et al. (2002) evaluated Kinnow on four rootstocks, viz.,
Jatti Khatti, Karna Khatta, Troyer and Carrizo at Abohar. On the basis of twenty year data,
they concluded that Kinnow mandarin trees on Jatti Khatti rootstock have vigorous growth and
longer tree life. Karna Khatta, Troyer and Carrizo rootstock combinations although remained
satisfactory for the initial 12-17 years, but showed gradual decline thereafter. Similarly in
another experiment by same scientists performance of Kinnow mandarin on seven rootstocks
viz., Jatti Khatti, Karun Jamir, Shekhawasha, jambhiri, Pectinifera, Estes rough lemon and
Cleopatra showed maximum tree volume on Jatti Khatti rootstock while trees on Cleopatra and
Shekhwasha rootstocks responded poorly.
Ahmed et al. (2006) investigated the performance of nine different rootstocks on
growth and yield of Kinnow. Out of the nine rootstocks studied, Volkamer lemon, Brazilian
sour orange and citrumello 4475 were recommended as reliable rootstock for the citriculture
12
industry of Pakistan. Josan and Thatai (2008) evaluated the growth of Kinnow on seven
different rootstock under Abohar conditions (Punjab). They recorded highest scion/stock ratio
in plants on Jambhiri and lowest in the plants budded on Cleopatra rootstock. Trees on Jatti
Khatti were reported to be the most vigorous and Pectinifera to be the least vigorous. Similarly,
Nasir et al. (2011) evaluated the response of Kinnow budded on three different rootstocks at
Sargodha, Pakistan. They observed vigorous growth with respect to plant height, spread, scion,
stock girth and canopy size on Rough lemon rootstock while Rangpur lime proved to be a
dwarfing rootstock.
Georgiou (2009) reported that Volkameriana, Yuma Ponderosa, C. macrophylla and
Citremon 1449 are the most suitbale rootstocks which could be used as a substitute of sour
orange for better plant height and vigor of local lemon variety ‘Lapithkiotiki’ in Cyprus.
Dubey and Sharma (2016) conducted many trials on rootstock influce on citrus cultivars and
found that plant height was more on rough lemon and RLC-4 rootstocks. Tazima et al. (2013)
revealed that maximum plant growth for the trees on and 'Caipira DAC' sweet orange was
obtained on trifoliate orange as compare to 'Volkamer' lemon and 'Cleopatra' mandarin
rootstocks. Shafieizargar et al. (2012) explained that the rootstocks have noteworthy effects on
most of the calculated characters, indicating that tree height of 'Queen' orange can be controlled
by using appropriate rootstocks. They discovered that Volkamer lemon is a better rootstock for
'Queen' orange. Espinoza-Nunez et al. (2011) discovered that rootstocks affected plant vigor,
particularly ‘Flying Dragon’ trifoliate, which declined tree height by 47% in contrast to the
‘Rangpur’ lime.
Legua et al. (2011) found that rootstock influenced fruit quality variables. C.
macrophylla and C. volkameriana appeared to encourage the bigger tree size. Jaskarni et al.
(2002) revealed that diploid trees of Kinnow trees were more lengthy than tetraploid trees.
Cimen et al. (2014) revealed that plants on Tuzcu No.31, and Gou Tou sour orange rootstocks
were the least affected regarding plant growth. Forner-Giner et al. (2010) established that trees
on rootstock C. volkameriana were the largest followed by trees on rootstock Carrizo citrange.
Cantuarias-Aviles et al. (2010) established that ‘Flying Dragon’ trifoliate showed a
distinct result over the ‘Okitsu’ mandarin trees performance, inducing lower canopy size.
Dubey and Sharma (2016) discovered that canopy amount was higher on rough lemon and
13
RLC-4 rootstocks while girth was higher on Billikichlli and RLC-4 rootstocks. Forner-Giner
et al. (2010) revealed that trees on C-13 hybrid selection were proficient in yield and canopy
spread. Jaskani et al. (2002) described that diploid Kinnow trees were larger in spread than
tetraploid. Singh et al. (2002) revealed that Rangpur lime rootstock reduced size of the tree.
Rootstocks may affect the capability of plants to take up water, nutrients etc. Kumar et al.
(1994) reported that dynamic rootstocks are required under arid environmental conditions, to
give a boost to citrus trees. Jaskani et al. (2002) discovered that diploid Kinnow trees attained
more stem girth than tetraploid ones. Shah et al. (2016) established that Meyer lemon when
grafted on sour orange rootstock affected scion diameter and scion length.
Stenzel and Neves (2004) grafted the lime on different rootstocks to check the influence
of rootstocks on tree vigor. They concluded that the most vigorous trees of lime with healthy
foliage were obtained from C-13 citrange and Poncirus trifoliata rootstock. Less vigorous
trees of lime with reduced canopy volume were recorded on African rough lemon, Sunki
mandarin and Cleopatra mandarin. Santos et al. (2016) performed an experiment to observe
the growth and performance of Persian lime on various rootstocks. Under experimental
conditions, Persian-08 and Persian-5059 rootstocks proved most promising rootstocks by
enhancing the vegetative performance and vigor of tree.
2.7 Effect of rootstocks on leaf mineral concentration
For the proper growth and maintenance of plant vigor, presence of adequate amount of
macro and micronutrients in plant body is of utmost importance.All of the nutrients present in
citrus plant are affected by rootstocks (Taiz and Zeiger, 2002). There is varying amount of
nutrients in scion cultivars grafted on different rootstocks. Less concentration of nitrogen was
present in scion bark of Kinnow as compared to nitrogen contents in rootstocks bark, in
rootstock bark there was higher amount of nitrogen; however, higher amount of potassium was
recorded in scion cultivar as compared to rootstock (Huchche, 1999). Satsuma mandarin when
grafted on sour orange and Carrizo citrange, highest leaf nitrogen contents were recorded from
Carrizo citrange rootstock while Sour orange rootstock depicted lower levels of nitrogen in
Satsuma mandarin (Creste, 1995). Varying amounts of nitrogen, phosphorus and potassium
were recorded in ‘Red blush’and Ponkan mandarin’ when grafted on different rootstocks
(Araujo et al., 1998; Fallah and Rodney, 1992)
14
Variable response of different scion cultivars grafted on different rootstocks was
recorded after the foliar spray of nutrients, which may be due to differential ability of rootstock
to absorb and transport nutrients, size of tree and root system, ratio of leaves to the whole tree,
fruit yield, ability of nutrients to cross bud-union, etc. The earliest studies about the absorption
of nutrients by citrus rootstock were those of Hass and Halma (1929) who reported that the
presence soluble Mg in any from was very low in lemon and Sour orange rootstock. Maximum
concentration of magnesium was recorded in sweet orange and grapefruit. It was also recorded
that presence of magnesium in bark of rootstock was variable in accordance with scion cultivar
which was grafted on rootstock. Wutscher et al. (1970) reported that in young grapefruit trees
grafted on sixteen rootstocks, there was no significant difference in leaf N and Na on different
rootstocks. But B, Mn, P, Zn and Cu content of leaves was affected by different rootstocks.
The leaves of Marsh Seedless grapefruit on Rough lemon showed a tendency to
accumulate more Na, Cl and B, and less Mg, while Cleopatra rootstock induced greater uptake
of Mg Na and B (Economides, 1976). Likewise, Leyden (1963) noted in the leaves of grapefruit
trees on Sour orange and Cleopatra that rootstocks influenced only K and Mg contents of
leaves. Whereas, trees which were on sour orange had higher K and lower Mg content than
those on Cleopatra. In a two year trial (Minessy and Bahry, 1966), leaf analysis of six scion
varieties showed that the percentage of Na was essentially the same for sour orange and
Cleopatra mandarin rootstocks. With sour oranges, K level was higher than with Cleopatra. In
other experiment, Wutscher and Shull (1972) found significant effect of rootstocks on the foliar
levels of N, K, Mg, Mn, Zn, Na, Cl and B fourteen years old nucellar Red blush grapefruit,
grown on thirteen rootstocks. Differences in the contents of P, Ca, Fe and Cu were non-
significant. Leaf Mn was high on Cleopatra and low on Carizzo, Troyer and Morton citranges.
In another trial on grapefruit, Wutscher et al. (1975) found that leaf Mn levels were
higher on Tachibana orange and B levels were relatively lower on Swingle citrumelo and
Succari sweet orange rootstocks. Similarly, Lakshman et al. (1975) from Andhra Pradesh
reported the differences in nutrient levels of Sathgudi orange grafted on seven rootstocks.
According to Roy (1943) who reported that leaves of citrus trees on orange rootstock contained
considerably less B than leaves of trees on Rough lemon stock. Similarly, Embelton et al.
(1962) employed a number of rootstocks for nucellar Eureka lemon scion and found that
Alemow rootstock resulted in a lower concentration of B in the leaves than other rootstocks
15
including Rangpur lime and Rutherford sweet orange. Similarly, Taylor and Dimsey (1993)
conducted an experiment at Irymple, in the Sunraysia district of Victoria and found that
Ellendale scion on Poncirus trifolata and Citrange rootstocks scion resulted in high to
moderate leaf N and P concentrations, while Dancy mandarin on Symons sweet orange
rootstock and low leaf N, P and K concentration. In case of micronutrients. Rough lemon
induced higher Mn and sweet orange induced high leaf Zn level. Likewise, Fallhahi and
Rodney (1992) found the maximum level of nitrogen, iron and manganese in Fairchild trees
grafted on Macrophylla rootstock. Maximum zinc was recorded in trees grafted on Volkamer
and minimum zinc was recorded on Carrizo citrange rootstock. Research conducted by Iyengar
et al. (1982) showed that Fairchild mandarin on Carrizo citrange had low Mn content.
Similarly, Georgiou (2000) reported that the N level of Nova leaves was maximum on Carrizo
citrange and Rangpur lime and the lowest was on sour orange, Estes Rough lemon and C
taiwanica. The level of Mg was higher on Carrizo and Troyer citranges whereas, lowest was on
Estes Rough lemon and Palestine sweet lime. In another study Georgiou (2002) found that the foliar N
in Clementine leaves was deficient on all rootstocks under investigation.
Absorption of water and nutrients from the soil and translocation of nutrients from roots
to other plant parts is significantly influenced by rootstock as rootstocks are responsible for the
formation of rooting of the plant and proliferation of the roots. Variation in absorption and
translocation of various nutrients from the soil may results in differences in many biochemical
and physiological processes of the scion cultivar (Fallahi and Rodney, 1992; Taylor and
Dimsey, 1993; Georgiou, 2000, 2002; Tsakelidouetal., 2002; Smith et al., 2004; Marathe et
al., 2006). Depending upon agro climatic conditions and soil characteristics, rootstocks can
perform differently, and these differences appear as varying performance of scion cultivars
grafted on them. Therefore selection of a rootstock for specific region is as much important as
the selection of scion cultivar (Davies and Albrigo, 1994).
In different climatic conditions of the world, effect of different rootstocks on leaf
minral contents of citrus has been investigated and documented (Georgiou, 2002). Effect of
different rootstocks on leaf mineral contents of some important citrus scion cultivars such as
Kinnow (Iyengar et al., 1982), grapefruit (Sharma et al., 2015) and Kagzi Kalan lemon (Dubey
and Sharma, 2016) have been investigated under same and varying set of agro climatic
conditions in India. Various trials have been conducted in Pakistan to specify the suitable
16
rootstock for the Kinnow mandarin in terms of leaf nutrient acquisition. Volkamer lemon and
Brazilian sour orange proved out to be reliable rootstocks for enhancing the nutritional status
of Kinnow mandarin. These rootstocks were further tested for other horticultural parameters
of Kinnow mandarin such as vegetative performance, yield characteristic and fruit quality
(Ahmed et al., 2006). While exploring the influence of different rootstocks on nutrient
acquisition in leaves of different scion cultivars, it was found that different rootstocks have
different effects on nutrient accumulation in scion cultivars (Taylor and Dimsey, 1993)
All the macro and micronutrients in leaves of Kinnow and other scion cultivars are effected by
rootstocks.
2.7.1 Nitrogen
Different mandarins were grafted on Poncirus trifoliata, Sour orange and Troyer
citrange and it was found that higher nitrogen contents in leaves of scion cultivar were recorded
from Poncirus trifoliata and Sour orange. Scion cultivar grafted on Sour orange had lower
nitrogen contents (Cassin et al., 1976). In another experiment a notable variation was recorded
in nitrogen levels of Valencia orange when grafted on three different rootstocks (Heinz and
wutsher, 1982). Coorge and Kinnow mandarin were grafted on seven different rootstocks to
investigate the capability of these rootstocks to manipulate the nutrient accumulation in scion
cultivar. It was observed that nitrogen levels of scion were significantly influenced by different
rootstocks. Poncirus trifoliata and Carrizo citrange proved out to be best suited rootstocks for
Kinnow and Coorge mandarin for enhancing the nitrogen levels of the plant (Iyenger et al.,
1982). Rough lemon and Sour orange were the traditionally using rootstocks in the world.
Various trials have been designed to test the performance of these rootstocks along with other
new rootstocks in order to find the sutibale substitute to these traditionally using rootstocks.
Highest nitrogen contents in scion cultivar were obtained from sour orange while performance
of Cleopatra mandarin was also satisfactory in order to enhance the nitrogen levels of scion
cultivars (Erdal et al., 2008)
Citranges rootstocks are the one of the most important group of the rootstocks
comprised of Carrizo citrange, Troyer citrange, Benton citrange and C-35 citrange. Usually it
is thought that performance of these rootstocks is poor under tropical and subtropical
conditions. Lemon is an important commercial cultivar of citrus. Performance of lemon stocks
17
were tested on different Citranges rootstocks and low nitrogen contents were recorded in lemon
on all citrnages rootstocks. So it was proved that citranges rootstocks are the poor performers
(Ahmed et al., 2006). Due to low nitrogen concentration various other aspects of plants such
as vegetative performance, tree vigor and overall yield is affected. In another experiment
conducted by Ahmed et al. (2006), lowest yield, less canopy volume and less vigorous trees
due to low nitrogen levels in Kinnow mandarin were recorded on citranges rootstocks, i.e.
Carrizo citrange and Troyer citrange. Significant effects of different rootstocks on nitrogen
accumulation capability in the leaves of scion cultivars were reported by Path et al., (1989).
Sour orange, Sovage citrange and Citrumello were used as roostsock for checking the nitrogen
and other macronutrients concentration in leaves of grapefruit. Effect of different rootstocks
was evident on the nutrient holding capacity and levels of nitrogen in the leaves of grapefruit.
Maximum nitrogen contents were found in the trees grafted on Sovage citrange rootstock.
Higher levels of phosphorus and potassium were obtained from the grapefruit trees grafted on
Citrumello rootstocks (Wutscher and Shull, 1972). A study was conducted for the evaluation
of different rootsocks i.e. Volkamer lemon, Troyer citrange, Brazilian sour orange and
Rangpur lime for enhancing the nutrient holding capacity of these rootstocks. Performance of
sour orange was superior than all other rootstocks by having maximum nitrogen contents in
leaves (Hafez, 2006). Contrary to this, a report was presented by Abou-Rawash et al. (1995)
which stated that Rangpur lime has the maximum capacity to hold nitrogen in the leaves and
scion cultivars grafted on this rootstock and has maximum vigor and canopy volume due to
high nitrogen accumulation.
Kinnow is commercial cultivar of citrus. Effects of different rootstocks have been
reported on manipulating different aspects of Kinnow mandarin. Kinnow was grafted on
different rootstocks i.e. Carrizo citrange, Yuma citrange, Rough lemon, Citrumello 4475 and
Citrumello 1452. Maximum nitrogen levels in leaves of Kinnow mandarin were recorded on
Citrumello 4475 and 1452. Due to maximum nitrogen concentration, vigor and canopy volume
of Kinnow mandarin was also higher on these rootstocks (Iqbal et al., 1999). In another study
maximum nitrogen levels were recorded in Kinnow mandarin grated on Poncirus trifoliata
rootstock. Poncirus trifoliata is one of the hardiest rootstocks due to its extensive and well
proliferated root system which enables the maximum absorption of nutrients from the soil and
18
ultimately leads to better performance of scion grafted on this rootstock (Fergusen et al.,
1990a; Araujo et al., 1998)
2.7.2 Phosphorus and potassium
Phosphorus is second most important macronutrient being responsible for proper
reproductive growth of the plant. Kinnow mandarin was grafted on different rootstocks to
check the absorption of phosphate and its translocation from roots to other scion cultivars.
Significant differences among the rootstocks were recorded regarding phosphorus contents in
the leaves of Kinnow mandarin. Kinnow trees grafted on sour orange rootstocks depicted the
highest levels of phosphorus (Fuller and Hilgeman, 1955). Significant variation among the
rootstocks was recorded in terms of phosphorus contents in the soil. Cleopatra mandarin
proved out to be most vigorous rootstocks by having maximum phosphorus contents in all
three scion cultivars. Due to higher phosphorus levels yield and fruit quality of all three scion
cultivars was excellent on Cleopatra mandarin. Besides rootstock influence it was also
recorded that, there exists a correlation between phosphorus contents in the leaves and the yield
capability of tree (Wallace et al., 1981). Lemon and Kinnow mandarin were grafted on some
dwarfing rootstocks such as Poncirus trifoliata and its hybrids to check the nutrient uptake in
the plants in different rootstocks. Maximum phosphorus uptake in lemon and Kinnow
mandarin was recorded on Poncirus trifoliata rootstock due to healthy roots system developed
by this rootstock (Wallace et al., 1981).
Potassium is the third most important primary nutrient, required by the plant for the
normal functioning. Several physiological processes are catalyzed by potassium. Rootstock
manipulate the phosphorus contents of the scion cultivar when grafted on them. Grapefruit was
grafted on different rootstocks to check the influence of different rootstocks on NPK contents
in the leaves. Valencia orange proved out to be best rootstock for grapefruit by having
maximum potassium contents in the leaves of scion cultivar (Smith et al., 1949). Kinnow was
grafted on different rootstocks to check the nutrient holding capacity of Kinnow grafted on
different rootstocks. It was found that Kinnow mandarin grafted on sour orange rootstock had
the maximum potassium contents (William et al., 1952). Another experiment was conducted
by Shah (2004) who evaluated the performance of different rootstocks i.e. Rough lemon
Rangpur lime in relation to Kinnow mandarin. Concentration of macronutrients was recorded
19
and it was found that Kinnow mandarin grafted on Cleopatra mandarin had the maximum
potassium contents while comparing to other rootstocks. Performance of Troyer citrange was
poorest of all.
2.7.3 Calcium and magnesium
Calcium and magnesium are considered as the building blocks of plant body as they
are the important constituents of many molecules such as carbohydrates and chlorophyll. They
are present in varying quantities in plants. Rootstocks are said to be responsible for the different
quantities of these elements in plant as the root system of the plant is formed by rootstocks
(Grace et al., 2012). Various trials have been performed to evaluate the concentration of
calcium and magnesium in citrus cultivars grafted on different rootstocks. Grapefruit was
grafted on different rootstocks to analyze the leaf mineral contents in the scion cultivar.
Maximum concentration of calcium and magnesium was recorded in grapefruit grafted on
Cleopatra mandarin rootstock. Sour orange rootstock has lower levels of calcium and
magnesium (Corton and Cooper, 1954). In another experiment Savage sour orange rootstock
showed superior behavior having maximum degree of compatibility with Eureka lemon.
Maximum levels of calcium and magnesium in the leaves of scion cultivar were recorded from
Savage sour orange rootstock. Photosynthetic activity of Eureka lemon was also higher on this
rootstock due to higher magnesium contents in the leaves (Watcher and shull, 1975)
Maximum concentration of calcium in the leaves of Ponkan (citrus ponesis) were found
when it was grafted on Sunki rootstock (Fan, 1981). Coorge and Kinnow mandarin showed
enhanced absorption of calcium and magnesium from the soil when grafted on different
rootstocks (Iyengar et al., 1982). Cleopatra mandarin and Shamouti mandarin were tested in
relation to Washington navel orange and absorbance of calcium and magnesium was checked.
Maximum calcium and magnesium in scion cultivars were recorded from Cleopatra mandarin
rootstock (Joseph and Mendel, 1982).
2.8 Effect of rootstocks on tree physiology
Physiological frameworks of scion cultivars are also controlled by rootstocks by
controlling the concentration of starch, sugars and other phyto-harmones (Morinaga and Ikeda,
1990). Tree growth parameters including CO2 assimilation, C-photo assimilation transport and
20
carbohydrate distribution, all are controlled by rootstocks. ‘Cleopatra mandarins’and ‘Forner-
Alcaide-13’ rootstocks were used in an experiment in which these rootstocks were grafted with
‘Navel oranges’. Results revealed that ‘Navel oranges’ which were grafted on ‘FA-13’
rootstock showed better photo assimilation rates from leaves to fruits, transporting higher
photo-assimilate from leaves to developing fruit and higher CO2 conductance rate as compared
to those grafted on ‘Cleopatra mandarin’ (Jover et al., 2012).
The physiology of rootstocks may vary under similar sets of management practices.
Moreover, scion behavior depends in part on the rootstock and induce effects on leaf gas
exchange (Syvertsen and Graham, 1985; Gonzalez-Mas et al., 2009). The influence of
rootstock on leaf gas exchange is taken as a key factor while studying the performance of scion
cultivars on different rootstocks. Measurement of physiological parameters and leaf gas
exchanges from the tree in rootstock-scion combination is therefore, important for
understanding the variation in leaf gas exchange parameters.
Rootstocks may influence the chlorophyll contents and relative water content sof scion
when grafted on it (Garcia Sanches, 2002). Literature on the effect of different rootstock on
RWC content of Kinnow has not been well documented and most of the study pertains to the
effect of salinity, different irrigation regimes or diurnal variation. Sharma et al. (2015)
however, in a study on the physiology of grapefruit cultivars on different rootstock observed
significant variation in RWC with higher values in scion leaf of Red blush on rough lemon.
Machado et al. (2010) evaluated the effect of low nocturnal temperatures under controlled
conditions on Valencia orange scions grafted on Rangpur lime and Citrumello rootstock. They
observed a decrease in leaf CO2 assimilation, stomatal conductance, mesophyl conductance
and CO2 concentration in plants grafted on both the rootstock but was more severe in plants
grafted on Rangpur lime rootstock.
2.8.1 Chlorophyll contents
Plant growth and photosynthetic behavior of young orange trees grafted on different
rootstocks was investigated. Results revealed that there was a significant effect of different
rootstocks on photosynthetic pigments in the orange leaves due to which varying activity of
photosynthesis was recorded in orange trees (Cimen et al., 2014).
There exists an evident difference of photosynthetic activity and chlorophyll fractions
between different rootstocks (Morinaga and Ikeda, 1990 and Bhatangar et al., 2011).
21
Photosynthesis and degree of carbon assimilation in plants in day hours of a year is a decisive
factor in plant vigor and productivity (Lawlor, 1995). Over all tree growth and yield capability
of scion cultivars grafted on different rootstocks is determined by translocation and movement
of carbohydrates from source (leaves) to sink (reproductive organs). Moreover, compatibility
between rootstock and scion plays a key role in movement of carbohydrates and other
important molecules between leaves and roots (Goldschmidt, 1999).
Performance of orange trees grafted on different rootstocks was evaluated with the
objective to check the effect of different rootstocks on chlorophyll fractions and other leaf gas
exchange parameters in calcareous soil. Varying amount of chlorophyll a and chlorophyll b in
orange trees was recorded on different rootstocks. Orange trees grafted on Carrizo citrange
rootstock had the highest transpiration rate owing to higher degree of stomatal conductance.
Non-significant effect of different rootstocks on net photosynthetic rate was also recorded. But
highest photosynthetic activity in the leaves of scion cultivar grafted on rootstock F-A5 showed
tolerance of this rootstocks against the calcareous conditions of the soil (Gonzalez-Mas et al.,
2009)
Rootstocks also influence the phytoharmones concentration in scion cultivars which
ultimately affects the overall tree health and yield (Fallahi and Rodney, 1992). ‘Canton Lemon’
rootstock gave high yield of 'Shatangju' mandarin by increasing the cell proliferation rate
during the phase of ripening. The differences which were observed in fruit sizes on different
rootstocks can be attributed to high concentrations of auxins in fruits which were grafted on
cantonal rootstock. AUX-1 upregulation was responsible for different levels of auxins (Liu et
al., 2015). Concentrations of auxins and gibberelins in scion portion and leaves depends upon
the vigor of rootstocks and concentration of phytoharmones in rootstocks (Tuzcu et al., 2004).
The largest tree size of `Shatangju 'mandarins was obtained from rootstock ‘Canton Lemon’
and ‘Grof lemon’ due to higher levels of phytoharmones in that rootstock, and the lowest tree
sizes was obtained from the ‘Red Mandarin’ and ‘Fragrant Orange’ rootstocks due to lower
concentration of phytoharmones in that rootstock (Liu et al., 2017).
22
2.8.3 Effect of rootstocks on carbohydrates concentration of citrus
Previously a lot of work has been done to investigate the effect of different rootstocks
on all vegetative and reproductive aspects of citrus tree (Bassal, 2009; Castle, 1987; Fallahi
and Rodney, 1992; Forner-Giner et al., 2003). It was thought that there exists a specific
mechanism which is responsible for the manipulations in different scion cultivars grafted on
different rootstocks. Distribution of carbohydrates between source to sink is largely
responsible for differences in yield capability of different scion cultivars. Rootstocks exert a
great influence on carbohydrates translocation from leaves to other parts, therefore, responsible
for variations in vegetative and reproductive aspects of different scion verities (González-Mas
et al., 2009). It is known that rootstock and scion, which are indispensable components in fruit
cultivation, affect each other in terms of activities for physiological events, such as carbo-
hydrate, plant nutrient and hormone in plant metabolism. Rootstocks have a considerable
impact on enhancing the concentration of photosynthetic molecules available to fruits and
other parts (Richer, 2007). Many studies concerning the effect on citrus tree physiology of
rootstock and scion interaction were conducted and the events occurring as a result of this
interaction have been tried to explain by the researchers (Calatayud et al., 2006; Gonzalez-Mas
et al., 2009; Vu et al., 2002) but there is no sufficient study about the effect of rootstocks on
accumulation of carbohydrate changes in citrus plant tissues.
Carbohydrates are essential for many important processes of plants. There is complete
dependence of deciduous trees on carbohydrates reserves for an early spring growth and bud
burst stage. Presence of carbohydrates in old leaves make them able to be active
photosynthetically even at old age. These carbohydrates reserves acts as back up energy supply
unit in conditions of less photosynthesis activity (Bustan and Goldschmidt, 1998;
Goldschmidt, 1999). Guardiola (1997) reported that the developing leaves initially draw
carbohydrates from other tree parts, but at flower opening they have completed the transition
from sink to source and become net carbohydrate exporters, and the developing flowers and
fruitlets draw both carbohydrates and mineral elements from other tree parts throughout their
development”. The management of internal resources in citrus species is not yet completely
clarified. In addition, no detailed study had found the effect of rootstocks on seasonal
carbohydrate variations in citrus tissues.
23
2.9 Effect of rootstock on fruit production and quality
Talking about fruit yield and quality of citrus, it is well discussed that role of rootstock
is important in reproductive capability and vegetative vigor of citrus (Demirkeser et al., 2005).
Delta and ‘Lana Late’ cultivars of orange were grafted on rootstocks and compatibility was
checked by observing average fruit yield and physico-chemical quality of fruits at three crop
maturity stages. Citrumelo was harmful rootstock for both shoots, while ‘GouTou’ rootstock
had low rate of compatibility and was harmful to Delta as well. Sour orange rootstock showed
the high level of compatibility with Delta (Maria and Marios, 2017). Similarly, Ali (2002)
observed the effect of different rootstocks on fruit quality and reported that maximum
percentage of juice and the best skin color of Fremont were found on sour orange rootstock,
while maximum TSS was found on Carrizo citrange rootstock. .
‘Troyer citrange’, ‘Cleopatra mandarin’ and ‘Poncirus trifoliata’ are some important
rootstocks which influence the yield and quality of citrus fruits (Giner et al., 2008). These
rootstocks were grafted with Washington Navel orange and yield and fruit quality. Troyer
citrange showed the highest accumulative yield and the largest fruit size. Poncirus trifoliata
produced semi dwarfing trees of Washington navel. In general scenario the performance of all
the three rootstocks was satisfactory and it can be concluded that these three rootstocks can be
used commercially for high yield and better quality citrus (Georgiou, 2000). In Texas an
experiment was established to find out a replacement rootstock of sour orange. The trial was
established by using ten rootstocks, i.e. ‘Troyer Citrange’, ‘Carrizo citrange’, ‘Swingle
citrumello’, ‘C-35’, ‘African shadow’, ‘C-22’, ‘C-146’, ‘C-57’ and Sour Orange’. ‘Rio Red’
cultivar of grapefruit was used as a scion. The results showed that all the plants on C-35 and
Swingle Citrumello dried and then died gradually. While maximum yield was obtained on
Carrizo citrange and C-22 rootstocks because of their resistance to CTV.
The impact of different rootstocks on overall yield, physico-chemical quality of fruit
and tree size of 'Valencia' orange in Florida citrus orchards revealed that ‘Sun Chu Sha’ and
‘Coleptera mandarin’ undergoes best performance over other rootstocks. Speaking of tree
survival and fruit productivity of individual trees, the performance of ‘Cleopatra mandarins’
was particularly good. This rootstock is not used as a commercial rootstock (Hutchison and
Heran, 1992).
2.9.1 Production
Yield of Kinnow was maximum on Jatti Khatti rootstock closely followed by Karun
Jamir and Estes Rough lemon and minimum yield was recorded on Cleopatra rootstock
(Sharma et al., 2002). Likewise, Brown (1920) while working at Peshawar reported significant
difference in yield of Malta common on Rough lemon, Sweet lemon, Sour orange, and Citron
rootstocks. Similarly, Sharma et al. (2002) found that out of four rootstocks studied over period
of twenty years using Campabell Valencia as scion, fruit production on Jatti Khatti was the
highest followed by Troyer citrange. Similar study was carried out by Al-Jaleel et al. (2005)
who tried seven rootstocks namely Citrus macrophylla, Volkamer lemon, Cleoptara mandarin,
Amblycarpa, Rough lemon, Citrus taiwanica and sour orange for Allen Eureka lemon and
reported that highest mean yield on Macrophylla and Vlokamer lemon whereas, trees on sour
orange were the least productive. Likewise, Georgiou (2002) reported that after eleven years
of observations Rough lemon and Rangpur lime were the best rootstock for the fruit production
of Clementine mandarin at Nicosia in Cyprus.
Hussain et al. (2013) studied performance of Common clementine on nine rootstocks
over a period of eleven years and found that trees on Carrizo citrange were most productive on
Da Hang Pao mandarin and Gou Tou sour orange were the least productive. Likewise, Smith
et al. (2004) evaluated Ellendale mandarin on seven rootstocks in Australia. Maximum yield
was recorded on Lockyer Rough lemon while low yield was observed on Emperor mandarin
rootstock.
In Egypt, Marisol clementine was evaluated on four rootstocks. Maximum yield was
obtained on Sour orange while poor performance of Cleopatra mandarin was recorded (Bassal,
2009). Similarly, Hilgeman (1975) compared the yield of seven Valencia oranges on four
rootstocks. The trees were planted at three different locations in 1959. Up to 1966 trees on
Rough lemon rootstock had the highest yield. Between 1968 and 1971 no difference in yield
existed in trees on Rough lemon and Willow leaf mandarin rootstocks. However, the lowest
yield was reported from trees on Cleopatra mandarin.
Under Cyprus conditions out of eleven rootstocks tested for Nova mandarin, sweet lime
was judged as the best whereas, Swingle citrumelo and Troyer citrange as low yielding
rootstocks (Georgiou, 2000). Likewise, Tazima et al. (2013) found that Swingle Citrumello
rootstock induced better growth and high yield in Satsuma mandarin when grafted on it