ABSTRACT
Crop plants grow almost entirely by photosynthesis. Thus, plant productivity in terms of primary production of biomass is simply a measure of the total photosynthesis of the plants less respiration, which has occurred during its growth. The amount of radiation intercepted by the crop during the growing season depends on the amount of incident radiation and the ability of the crop to intercept it. The crop plants need to perform at optimal level not only with respect to capturing light in crop canopy, but to efficiently utilise it for greater dry matter yield. The higher rate of photosynthesis (Pn) per unit leaf area, therefore becomes important. In most crop species, however, there has been little change in the rate of leaf photosynthesis per unit area to accompany the substantial genetic increase in grain yield. Photosynthesis can be enhanced through bioengineering the stomata, so that in water-rich areas they might be modified to stay open even longer.
