Enhancing Crop Productivity Through Increased Abiotic-Stress Tolerance and Biomass Production

Crop yields are limited by a combination of biotic stresses, abiotic stresses, and nutritional factors. various analyses have suggested that abiotic stress—due primarily to drought, heat, cold or salinity—is the major factor that prevents crops from realizing their full yield potential (e.g. Boyer, 98 ; edmeades, 008). Increases in crop yields through conventional plant breeding result from genetic enrichment by introducing multiple quantitative trait loci (QtLs), including, presumably, QtLs for abiotic and biotic stress resistance. for example, tollenaar and wu ( 999) have provided evidence that yield increases in corn (Zea mays L.) in recent decades have been partly due to enhanced stress tolerance during the grain filling and late-maturation stages. Separately, recent interest in renewable fuels has led to a substantial increase in ethanol production from plant material. although the initial emphasis has been on using starch from corn, and to a lesser extent from other food grains, this is unlikely to be sustainable in the long term; alternatives such as cellulose from specially grown “biomass” crops are likely to be a more important substrate for ethanol production. The challenge here is to increase total vegetative biomass rather than seed yield, similar to the approach one might take in forage or silage-crop improvement. This paper describers several examples of how modern crop technologies, in particular transgenic approaches, may be applied to broaden crop tolerance of various abiotic stresses and to increase total biomass in non-seed crops.