Nutrient availability

Temperature

Daylength

Solar radiation

Soil moisture/ Rain Irrigation

Fertilizer

Population

Sowing date

Cultivar

Mineral nutrition

Phenological development

Canopy development

Biomass accumulation

Partitioning

Yield QualityPROCESSES

ENVIRONMENT MANAGEMENT

Relationship between environment and management factors and the physiological processes that regulate crop yield and quality. (Source: Hay & Porter 2006).

Light

Complex & dynamic signal

Quantity of lightphotons falling

/area/time

Quality of lightplant responses

Growth vs Development• Growth: an irreversible increase in DM

- function of light interception and - photosynthesis and then

- assimilate partitioning

• Development: irreversible change in the state of an organism

- fixed pattern and reversion is rareEg. silking,

pod initiation, dough development

A) Vegetative

• Emergence and

• Leaf appearance rates (phyllochron).

B) Reproductive

• Time of flowering (anthesis),

• Duration of grain fill.

Driven by temperature modified by photoperiod and vernalization

Plant development

Sowing to emergence

Thermal time - soil temperature

Temperature (°C)

0 10 20 30 40Day

s to

75%

ger

min

atio

n

0

5

10

15

20

25

Ryegrass

Time for germination

0 10 20 30 40Ger

min

atio

n ra

te (

1/da

ys)

0.0

0.1

0.2

0.3

0.4

Temperature (°C)

Germination rate

Tb

Topt

Tt = 65°Cd

Tmax

Thermal time

• Tt = Thermal time (°Cd)

= Tmax + Tmin - Tb

2

• Growing degree days (GDD) • Heat units (HU)

20

15

10

5

0

20

30

10

00 3 6 129 15 18

Mean temperature (oC)

No

de

in

terv

al

(d)

Massey node appearance

Whero node appearance20

15

10

5

0

20

30

10

00 3 6 129 15 18

Mean temperature (oC)

No

de

in

terv

al

(d)

Massey node appearance

Whero node appearance

Tb=

Temperature (oC)

0.5

0.4

0.3

0.2

0.1

00 2 8 10 12 14 16 18 204 6

Whero 27oCd/node

Dev

elo

pm

ent

rate

(n

od

es/d

)

Massey 37oCd/node

Temp. Interval

5.9 18.5 0.054

8.7 7.5 0.133

12.0 3.6 0.280

15.1 2.3 0.435

Crop Growth and Yield

1) C = E*Q C = daily rate of DM prod.

E = radiation use efficiency

Q = PAR intercepted

2) Y = HI*C*dt Y = seed yield/unit area

HI = harvest index

Year Yield Height HI BY (t/ha) (m) (%) (t/ha)

Little Joss 1908 5.22 1.42 36 14.5LJ (low fert.) 3.30 1.12 34 9.7

Cap- Dep. 1953 5.86 1.10 42

rht2

Hobbit 1977 7.30 0.80 48Norman 1981 7.57 0.84 51 14.8Nor. (low fert.) 4.59 0.64 49 9.4

Change in HI over time

Days after anthesis

0 10 20 30 40 50 60 70

600

400

200

0

-200

Ch

ang

e in

DW

t(g

/m2 )

Days after anthesis

0 10 20 30 40 50 60 70

600

400

200

0

-200

Ch

ang

e in

DW

t(g

/m2 )

Grain

Stem

rht2old

Days after anthesis

0 10 20 30 40 50 60 70

600

400

200

0

-200

Ch

ang

e in

DW

t(g

/m2 )

Days after anthesis

0 10 20 30 40 50 60 70

600

400

200

0

-200

Ch

ang

e in

DW

t(g

/m2 )

Grain

Stem

rht2old

Light

- photosynthesis to produce CHO’s for growth.

- Photosynthetically active radiation (PAR) is in the visible range (400-700nm).

- Conversion of PAR to DM ~2.5 g DM /MJ/m2 for C3 plants~3.8 g DM /MJ/m2 for C4 plants

Q (MJ m-2)

C (

g m

-2)

00

300

300

600

600

150 450

900

1200

1500

Q (MJ m-2)

C (

g m

-2)

00

300

300

600

600

150 450

900

1200

1500

Dryland

Irrigated

Total DM production (C) from successive harvests and intercepted PAR (Q) for field peas in5 experiments in 4 seasons with different cultivars, sowing times and irrigation treatments.The form of the regression is: 2.36±0.03 g DM/MJ PAR (R2=0.97). Source: Wilson 1987

Intercepted solar radiation (GJ/m2)

0.0 0.5 1.0 1.5 2.0

Tota

l DM

(t/h

a)

0

10

20

Intercepted solar radiation (GJ/m2)

0.0 0.5 1.0 1.5 2.0

Tota

l DM

(t/h

a)

0

10

20

Apples

Barley

Potatoes

Sugar beet

(Source: Monteith, 1977)

0

200

400

600

800

1000

1200

0 2 4 6 8 10 12 14 16 18 20 22 24

Time of day (h)

Irra

dian

ce (

W/m

2 ) December (14.4 MJ PAR/m2/d)

March (6.5 MJ PAR/m2/d)

June (2.2 MJ PAR/m2/d)

Global irradiance on sunny days (W/m2)

Photosynthetically active radiation (PAR)

PAR averages 11.4 MJ/m2/d in summer (Dec) 2.2 MJ/m2/d in winter (Jun)

and therefore potential dry matter yield is:

summer: 11.4 x 2.5 = 28.5 g/m2 = 285 kg DM/ha/dwinter: 2.2 x 2.5 = 5.5 g/m2 = 55 kg DM/ha/d

Conclusion: Available PAR levels are non-limiting for pasture production

in New Zealand

0

50

100

150

200

250

J F M A M J J A S O N D

Month

Gro

wth

rat

e (k

g D

M/h

a/d

)

0

50

100

150

200

250

J F M A M J J A S O N D

Month

Gro

wth

rat

e (k

g D

M/h

a/d

)Pasture production in Canterbury

Potential

Actual

Potato

0 1 2 3 4 5 6Pro

po

rtio

n o

f in

cid

ent

PA

R i

nte

rcep

ted

(%

)

90

70

50

30

10

Green Area Index0 1 2 3 4 5 6Pro

po

rtio

n o

f in

cid

ent

PA

R i

nte

rcep

ted

(%

)

90

70

50

30

10

Critical GAI

(Source: Khurana & McLaren 1982)

Leaf area index (LAI) = area of leaf lamina (m2)area of soil surface (m2 )

influenced by; i) Species LAI Cmax

(kg/ha/d)white clover 3.0 121ryegrass 7.1 156mixture 4.5 140maize 7.4 261

Measurements Light

environment

Photosynthesis

Soil moisture

Chemical Analysis:- N (shoots and roots)- Starch in roots- Soluble sugars in roots

Others:- SLW- SPAD- Chla+b

Light level (PPFD mmol m2/s)0 500 1000 1500 2000 2500

Pho

tosy

nthe

tic r

ate m

mol

CO

2/m

2 /s

-5

0

5

10

15

20

25

30

Non Limited

Nitrogen 3.5%

Temperature 14oC

Predawn LWP -10 bar

(Source: Peri et al. 2002)

Pm

axs

(dim

ensi

onle

ss)

Temperature (oC)

0 5 10 15 20 25 30 350.0

0.2

0.4

0.6

0.8

1.0

1.2Pmaxs = 0.99xe(-0.5x(T-20.4/7.90)2)

19-23oC

(Source: Peri et al. 2002)

Predawn leaf water potential (bars)

-18-16-14-12-10-8-6-4-20

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Pmaxs = 1.0716 - 0.0765x

Pm

axs

(dim

ensi

onle

ss)

(Source: Peri et al. 2002)

Foliage N concentration (g N/kg DM)

0 10 20 30 40 50 600.0

0.2

0.4

0.6

0.8

1.0

2.6% N 5.2% N

Pm

axs

(dim

ensi

onle

ss)

(Source: Peri et al. 2002)

Modelling photosynthesis

C Pmaxs

10 0.47

19 1.00

23 1.00

31 0.38

%N Pmaxs

1.5 0.25

2.6 0.70

5.2 1.00

5.9 1.00

f (T) f (N) f (lp)

lp Pmaxs

-0.1 1.00

-1.2 1.00

-14.0 0.00

-16.0 -0.05

* *Ppmax *

Where Ppmax is maximum measured photosynthetic rate of

27.4 mmol CO2 m-2 s-1

Most basic approach(Source: Peri et al. 2002)

200 kg N/ha

anthesis

Control (0 N)

Days after crop emergence

Gre

en l

eaf

area

in

dex

6

3

00 150 300

100 kg N/ha

(Source: Green 1987)

Effect of water stress on relative yield

Soil moisture deficit (mm)

0 50 100 150

Rel

ativ

e yi

eld

0

50

100

I+ND+N

y = -1.45%/mm

78 mm

DL

(Source: Mills et al. 2006)

Ryegrass

Clover

50 mm

250 mm

Water extraction (mm water/10 cm soil)

0 8 16 24 32

Dep

th (

m)

2.5

2.0

1.5

1.0

0.5

0.0

LismoreStoney loam

(100 mm)

WakanuiSilt loam(380 mm)

Patterns of water extraction

Rep 1

Rep 2

Rep 3

Experiment site

Growth rates (2 year means)

Month

J A S O N D J F M A M J J

Gro

wth

rat

e (k

g/ha

/d)

0

30

60

90

120 I +N 21.9 t/ha

I -N

9.8 t/ha

15.7 t/ha

D+N

6.3 t/ha

D-N

Water stress effect on yield

Thermal time

0 1000 2000 3000

DM

yie

ld (

t/ha

)

0

10

20

30I+N

y = 7.0 kg DM/ha/oCd

21.9 t/haD+N

15.7 t/ha

21 Nov 30 Jan

(Source: Mills et al. 2006)

DM yield response to thermal time (Tb = 3°C)

Thermal time (°Cd)

0 1000 2000 3000

DM

yie

ld (

t/ha

)

0

10

20

30I+N

y = 7.0 kg DM/ha/oCd

I–N

y = 3.3 kg DM/ha/oCd

21.9 t/ha

9.8 t/ha

(Source: Mills et al. 2006)

Ryegrass only

13 kg DM/ha/mm

Lucerne 28 kg DM/ha/mm

20 kg DM/ha/mm

Spring WUE: legume = (nitrogen)

Water use (mm)

0 100 200 300

Acc

umul

ated

DM

(t

DM

/ha)

0

2

4

6Ryegrass / clover

(Source: Moot et al. 2008)

Clover yield (kg DM/ha)

0 500 1000 1500 2000

Fix

ed N

(kg

N/h

a)

0

10

20

30

40

50

60

White cloverSub clover

Biological N fixation

y = 28.0±0.66x (R2=0.96)

(Source: Lucas et al. 2010)

Conclusions

• Light interception drives growth• Nitrogen affects leaf area expansion• Temperature affects leaf area expansion• Water affects leaf area expansion• NTW affect photosynthesis• Pests and diseases affect leaf area!• CANOPY MANAGEMENT