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K EFFECTS ON YIELD QUALITY
Adolf Krauss
International Potash Institute
Basel, Switzerland
Contents
Why quality?
Where is the link between K and quality?
What can we prove?
Conclusion
… K effects on yield quality
Why quality?
… K effects on yield quality
… Why quality?
… because urbanisation is advancing
Regional urbanisation
0
10
20
30
40
50
60
70
80
90
100
1940 1960 1980 2000 2020 2040
sh
are
of
urb
an
ite
s
Brazil
EU-15
India
… Why quality?
… because urbanisation is advancing, that is more urbanites and less rural people - also in Brazil
Demographic development of Brazil as compared to
EU-15
0
50
100
150
200
250
300
350
1940 1960 1980 2000 2020 2040
M in
ha
bit
an
ts
Brazil urban
Brazil rural
EU-15 urban
EU-15 rural
… Why quality?
… the society is also rapidly ageing like in the OECD countries
Ageing society in OECD countries
0
200
400
600
800
1000
1200
1400
1960 1970 1980 1990 2000 2010 2020 2030 2040 2050
millio
n in
ha
bit
an
ts
> 65 yr
15-64 yr
<15 yr
… Why quality?
… with income and ageing the food habit changes
… why quality?
… less cereals and more fruits and vegetables ...
Change in the diet in Brazil compared to EU-15
0
50
100
150
200
250
300
1950 1960 1970 1980 1990 2000 2010
su
pp
ly k
g/c
ap
/ye
ar
Brazil cereals
Brazil fruits&veg
EU-15 cereals
EU-15 fruits&veg
… why quality
… less cereals and more fruits and vegetables ...
Per capita food supply 2000 in selected countries(FAO, 2004)
0
50
100
150
200
250
300
EU-15 Brazil India
kg
ce
rea
ls;
fru
its
&v
eg
eta
ble
s
cereals
fruits&veg
… why quality?
… and more vegetable oil with raising income ...
Relationship between per capita GDP and
consumption of vegetable oil(FAO/CIA 2004)
y = 0.5406x + 6.3747
R2 = 0.8866
0
5
10
15
20
25
30
0 10 20 30 40
GDP '000 USD per capita
kg
/ca
p v
eg
oil
… why quality?
… and customers look first for quality when selecting food
Relative importance of product attributes in
product choiceafter TRAILL, 1999
quality
26%
price
17%
reputation
14%
freshness
9%
guarantee
9%
9 others
25%
Why quality?
What is quality?
… K effects on yield quality
… what is quality?
Quality is
…an intrinsic property of food by which it meets predefined standard requirements. Determinants of food quality can be grouped into several properties. Food quality therefore refers to the value, which is subjectively or objectively attached to food with respect to quality properties…
(Alabaka, 1999)
… What is quality?
Nutritional properties Functional properties
Hygienic
properties
Organo-leptic
properties
Environmental compatibility Safe food
FOOD QUALITY
Why quality?
What is quality?
Where is the link between K and quality?
… K effects on yield quality
… Where is the link between K and quality?
… for example, in N metabolism …
PEP NH3
protein
NO3 NO3
K+Malate- K+NO3
K+ K+
K+Malate-
Malate Pyruvate
HCO3
SHOOT
ROOT
KNO3
XYLEM
K+
Model for the circulation of potassium in relation to nitrate and malate transport (after MARSCHNER, 1995)
PHLOEM
CO2
… for example, in sugar transport
… Where is the link between K and quality?
… for example, in sugar transport
… Where is the link between K and quality?
Effect of K status of cane on sugar transport (exposure 4 hrs)
(after HARTT, 1969)
0
20
40
60
80
100
120
deficient K adequate K
pe
rce
nt
14C
tra
ns
po
rt f
rom
fe
d le
af
stalk
adjacent leaf
fed leaf blade
… unless excessive Cl- affects sucrose storage in cane stalks
Cl-+K+
Xylem Transport Cl- and K+
Cl- and K+ Sucrose
Synthesis
Cl-+K+ Sucrose
Cl-+K+
Sucrose
Cl-+K+
Sucrose
Retrans location Cl-+K+
Exchange processes
Leaves
Stalk storage
cells
Roots
Cl-+K+
Exchange processes of Cl- and sucrose in sugarcane (KRAUSS, 1992)
… Where is the link between K and quality?
Relationship between Cl and sucrose in cane stalks
y = 71.015x2 - 171.67x + 110.17
R2 = 0.8278
0
5
10
15
20
25
30
35
40
0.5 0.7 0.9 1.1 1.3 1.5
Cl % in DM
su
cro
se
% in
DM
… unless excessive Cl- affects sucrose storage in cane stalks
Cl-+K+
Xylem Transport Cl- and K+
Cl- and K+ Sucrose
Synthesis
Cl-+K+ Sucrose
Cl-+K+
Sucrose
Cl-+K+
Sucrose
Retrans location Cl-+K+
Exchange processes
Leaves
Stalk storage
cells
Roots
Cl-+K+
Exchange processes of Cl- and sucrose in sugarcane (KRAUSS, 1992)
… Where is the link between K and quality?
… for example, in water utilization
K 3 K 1 K 2
Wilting of sugar beets as affected by K supply
… Where is the link between K and quality?
… K regulates stomata aperture
… Where is the link between K and quality?
Potassium and stomata aperture(from MARSCHNER, 1995)
0
50
100
150
200
250
300
350
400
450
open stomata closed stomata
K c
on
ten
t (1
0-1
4 m
ol/s
tom
ata
)
0
1
2
3
4
5
6
vo
lum
e (
10
-12 l)
K
guard cellvolume
… K is the insurance for quality formation even under climatic ... P
hoto
syn
the
sis
(µm
ol C
O2 m
-2 s
-1)
Drought Stress
Low K
Adequate K
0
10
20
30
40
50
LOW MILD SEVERE
From CAKMAK, 2003
… Where is the link between K and quality?
… or biotic stress
… Where is the link between K and quality?
Unbalanced high N sugar
balanced N sugar
Krebs cycle
Krebs cycle
secondary compounds
secondary compounds
Phenols Quinones
Phenols Quinones
organic N organic N
soluble org N
compounds
soluble org N
compounds
Synthesis of pathogen repellents in plants as affected by the level of N supply (after GRAHAM, 1983)
Why quality?
What is quality?
Where is the link between K and quality?
What can we prove?
… K effects on yield quality
… What can we prove?
… adequate K improves the nutritive value
- for instance in wheat - higher protein content and better appearance
+K -K
Yield and quality of wheat in India as affected
by K
3.8
4
4.2
4.4
4.6
4.8
5
5.2
5.4
-K +K
t/h
a
10.4
10.6
10.8
11
11.2
11.4
11.6
11.8
% p
rote
in
grain yield
protein content
… What can we prove?
… adequate K improves the nutritive value
- with higher oil content, more people can get their daily need from the same field
+K -K
Yield and quality of oilseed rape in China as
affected by K
2.6
2.65
2.7
2.75
2.8
2.85
2.9
-K +K
t/h
a
36.8
37
37.2
37.4
37.6
37.8
38
38.2
38.4
38.6
% o
il
seed yield
oil content
… What can we prove?
… adequate K affects the functional property
- with higher sugar content, less cane is required for the same sugar output and thus, less energy for transport and extraction
Relationship between soil K absorption ratio (K in % of
CEC) and stalk size and sucrose content of cane in
Egypt
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
1.5 2 2.5 3 3.5
% K on CEC
kg
/sta
lk
17
17.5
18
18.5
19
19.5
20
su
cro
se
%
Poly. (sucrose %)
Poly. (stalk kg)
… What can we prove?
… adequate K affects the functional property
… the same applies to potato and starch production
Tuber yield and quality of potatoes in Poland
20
22
24
26
28
30
32
34
36
38
40
NP NPK NPK+Mg
tub
er
t/h
a
15.4
15.6
15.8
16
16.2
16.4
16.6
16.8
17
17.2
17.4
% s
tarc
h
tuber yield
starch content
… What can we prove?
… K is involved with organo-leptic properties
… amino acids are important components for tea quality ...
Impact of balanced fertilization with K and Mg on
quality of tea (China)
24
25
26
27
28
29
30
NP NPK1 NPK2
am
ino
ac
ids
mg
/g m
ad
e t
ea
-Mg
+Mg
… What can we prove?
… K is involved with organo-leptic properties
… and potato crisps keep a bright colour when the tubers are fed with adequate K because it lowers the content of reducing sugars
-K +K
Color index of potato chips as affected by K
supply
4
4.5
5
5.5
6
6.5
7
7.5
8
0 108 217 315
kg/ha K2O
co
lor
ind
ex (
10=
excellen
t)
… What can we prove?
… K controls hygienic properties
… mouldy fruits, cracked tomatoes from K deficient plants are disliked by consumers ...
… What can we prove?
… K controls hygienic properties
… also black spots in potato tubers can be controlled by adequate K ...
Relationship between K supply and
incidences of black spots in potato tubers
(Germany)
0
1
2
3
4
5
6
7
0 100 200 300
kg/ha K2O
bla
ck
sp
ot
inc
ide
nc
es
0
5
10
15
20
25
K m
g/k
g
tubers with black spot
K-content of tubers
NP control NP + KMgS
O=C
HO-C
HO-C
H-C
HO-CH
CH2OH
… What can we prove?
… K enhances the content of functional compounds
… Vitamin C and antioxidant contents are improved by adequate K ...
Balanced fertilization increased yield and
improved quality of cabbage in Russia
68
70
72
74
76
78
80
82
84
86
-K +K
He
ad
s t
/ha
235
240
245
250
255
260
265
270
275
Vit
C m
g/k
g
head yield
Vit-C content
O
Vit C
Effect of K on isoflavones in soybean seeds (BRUULSEMA*, 2002)
1650
1700
1750
1800
1850
1900
1950
2000
2050
2100
-K +K
tota
l is
ofl
av
on
es
pp
m (
ex
pre
ss
ed
as
ag
lyc
on
es
)
… What can we prove?
… K keeps plants healthy and hence the food
POTASSIUM
CONTROL
-K -K
+K +K
… What can we prove?
… K improves the appearance and shelf-life of many crops
Economy of potato tubers in India (Bansal & Shahid, 1998)
5
10
15
20
25
30
VCR harvest VCR 2 weeks later VCR 4 weeks later
VC
R f
or
K2O
100 kg/ha K
150 kg/ha K
… What can we prove?
… K improves the appearance and shelf-life of many crops
Tuber yield and storage loss of potato tubers (Bansal & Shahid Umar, 1998)
15
17
19
21
23
25
27
29
31
33
0 100 150
kg/ha K2O
tub
er
yie
ld t
/ha
0
1
2
3
4
5
6
sto
rag
e lo
ss
% yield
storageloss (4weeks)
… What can we prove?
… K use meets the environmental requirements
… because at balanced fertilization, N use efficiency is improved
Residual NO3 in the subsoil (kg/ha) as
affected by fertilization in China
0
20
40
60
80
100
120
140
160
farmers practice=excessive N
unbalancedhigh N
balanced NPK
Impact of Farmer's practice, FP and Site
specific nutrient management, SSNM on
recovery efficiency of N fertilizers, REN, of rice
in SE Asia
4.8
4.9
5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
FP(111-18-17 kg/ha N-P-K)
SSNM(120-22-66 kg/ha N-P-K)
gra
in y
ield
20
22
24
26
28
30
32
34
36
38
RE
N %
rice yield
REN
… growth limitation of the shoot e.g. at K deficiency signals to the roots to refrain from further N uptake, so, the plant cannot be forced to absorb N above its needs …
Low demand high demand
shoot shoot
root root
Growth Growth
Phlo
em
Phlo
em
Xyle
m
Xyle
m
Growth Growth
Nitrogen
after ENGELS & MARSCHNER, 1995
Nitrogen
… What can we prove?
… K effects on yield quality
In conclusion:
Producer
• globalisation
• trade liberalisation
• competition
• selective and critical consumers
• ...
Consumer
• healthy food
• cheap food
• plenty food
• protection of the environment
• safeguarding natural resources
• ...
• legislative measures
• trade barriers
• gaps in knowledge
• agric. practice
• quality auditing
• confidence of consumers
… K effects on yield quality
… Thank you