Notes On Yield Improvement Stagnation

1537 WordsMay 15, 20177 Pages
YIELD IMPROVEMENT STAGNATION Actual yield, per unit time and per unit land, saw a significant increase over 30 years from around the 1960s due to intensified crop management involving improved germplasm, increased use of fertilizer, producing two or more crops per year and irrigation (Cassman, 1999; Finger, 2010). The exploitable gap between yields achieved and genetic yield potential is closing due to these advancements, however yield potentials are increasing at a much lower rate than the expected increase in demand. The increase in food demand means that average farm yields have to reach 70 to 80% of the yield potential ceiling within 30 years in different major cereal systems to keep up with demand (Cassman, 1999). However, several…show more content…
There is some evidence that the improvements in yield made since the Green Revolution, that focus primarily on carbon partitioning, have been accompanied by higher photosynthetic rates relating to leaf area and cooler canopies (Fischer et al., 1998). However, photosynthesis has had limited improvement in crops and falls significantly short of its biological limit, and thus presents itself as a crucial mechanism by which genetic yield potential can be increased in major crops (Long et al., 2015). BIOLOGICAL IMPROVEMENTS Yield potential is determined by the product of the available light energy and genetic properties: light capture efficiency, conversion of intercepted light to biomass efficiency and the proportion of said biomass partitioned into grain (Long et al., 2006). Current plant breeding has brought the proportion of biomass partitioned into grain, and light capture efficiency to their theoretical maxima. This leaves the efficiency of conversion of intercepted light to biomass as the only route yet to be fully exploited in order to improve yield potential. There are two main constraints on this conversion efficiency: stressful environments and the non-linearity of leaf photosynthesis response to increased solar energy. For example, C₃ plants have a leaf photosynthesis saturation level of approximately 25%
Open Document