Seminars

The yield potential of crops is determined by their efficiency of capturing available light energy (εi), the efficiency of converting intercepted light into biomass (εc), and the proportion of biomass partitioned into grain (η). The remarkable yield gains of the Green Revolution in the middle of the 20th century resulted from plant breeders bringing η and εi for major crops close to their theoretical maxima, leaving improved photosynthetic efficiency as the only yield determinant with sufficient capacity to double crop productivity. Crop plants in the field, even with sufficient water and nutrient availability, operate far below the theoretical photosynthetic efficiency. A major reason for the low operating efficiency is that light energy distribution in crop canopies is suboptimal wherein at full sunlight leaves at the top of the canopy absorb as much as 500% more light then they can utilize while photosynthesis just one leaf layer lower in the canopy are light limited. Modeling suggests that reducing leaf chlorophyll by 70% would maximize canopy photosynthetic efficiency. Growth chamber and field experiments with reduced chlorophyll content soybean and sorghum have been conducted to test the hypothesis that Crop Plants Too Green.