0838 crop yield maximization
DESCRIPTION
Fasoula SRI SeminarTRANSCRIPT
Crop Yield Maximization
SRI Seminar
FasoulaJuly, 2008
55
65
75
85
95
105
115
3 4.5 6
Density (plants/m2)
Yie
ld (
t/ha)
Source: adapted from Russell (1986)
1970 era single-cross hybrids
1930 era double-cross hybrids
Crop yield maximization – 1. Use of monogenotypic cultivarsto erase the plant differences due to genetic competition
2
3
4
5
6
7
Inbredlines
open-poll
doublecrosses
3-waycrosses
hybrids
Gra
in y
ield
(t/
ha)
Source: Jugenheimer 1976; Fasoula and Tollenaar 2005
CV=33%
CV=26%
CV=24%
CV=23.5%
CV=22%
Crop yield maximization – 2. Use of monogenotypic cultivarsthat possess high individual homeostasis (stability)
Crop yield maximization
3. Utilization of density-independentmonogenotypic cultivars
Choice of the plant ideotypeMany fertile tillersDeep and extensive root system
Maize ideotype: uni-culmed and single-eared
Maize hybrids have become heavilydependent on a specific plant density
The case of density-dependence in maize
0
2
4
6
8
10
0.5 1 2 4 8 12 18 24
Density (plants/m2)
Cro
p y
ield
(t/h
a)
Pioneer 3902
Maize hybrids tend to be density-dependent
Source: Fasoula and Tollenaar 2005
Year of introduction
1930 1940 1950 1960 1970 1980 1990
Yie
ld (
t/h
a)
0
2
4
6
8
10
12
14
1 plant/m2, r
2= 0.06
7.9 plants/m2 , r
2 = 0.86
3 plants/m2 , r
2= 0.56
Maize hybrids were not selected for high plant yield
Source: Duvick 1997
Example of density-independent and density-dependentcultivars in tomato
Density (Plants/m2)
Yie
ld (
t/ha
)
Source: Fery and Janick 1970
0,75 1,75 4,25 10,25 2511
22
34
4556
112
IndeterminateJointlessDeterminateMiniatureDwarf
MULTIPLE HARVEST
DisadvantagesMore frequent weeding (farmers may favor
high densities as a means to suppress weeds)
Medium plant densities
AdvantagesLower seed cost
Better drought and lodging resistance
Fewer disease problems
Security in adversity
SRI advantage
Wider plant spacing – many tillers
Source: Uphoff 2006
AdvantagesMany tillers
Extensive and deep root system (less water)
Better resistance to drought and lodging
Fewer disease problems
Crop yield compensation in case of adversity
Exploitation of the plant yield genetic
potential
SRI Rice plant ideotype in wider spacing
Growth resources must be ample, readilyavailable, and evenly distributed across the field
Crop yield maximization – Precondition 2
SRI advantageCareful field and soil preparationEnhanced soil organic matterIncreased soil aerationCareful water management
1. Germination and growth of plants must be fast and synchronous
SRI advantage: early transplantingYounger seedlings can achieve more uniform growth and will mature quicker
SRI advantage: square grid pattern
2. Plants must be evenly distributed across the field
Crop yield maximization – Precondition 3
SRI achieves better stand uniformity and thus higher crop yield
Source: Uphoff 2006
Smaller CV
Cultivars selected for the environments that aredestined to exploit
marginal environments (poor soils, drought, etc)favorable environments
Monogenotypic cultivars with high stability
Density-independent cultivars (less variable yields)25 × 25, 30 × 30, 50 × 50
Conditions that will maximize SRI efficiency
Wider spacings (50 × 50) can allow farmers to visuallyselect the best plants for the following year(Participatory Breeding)
Frequent weedingweeds will interfere with the even growth
Cultivars not adapted to the environmentsutilized by the farmers
Density-dependent cultivars
Cultivars with low tillering capacity (i.e., NPT of IRRI)
Conditions that will minimize SRI yields
Weeds in the field
A final thought
The plant genome is dynamic and plastic and can
activate mechanisms that release adaptive
variation to the constantly changing environmental
conditions, whether these are favorable or unfavorable