CULTIVAR DIFFERENCES IN LEAF PHOTOSYNTHESIS AND GRAIN-YIELD OF WHEAT UNDER SOIL-WATER DEFICIT CONDITIONS

Cultivar differences in leaf photosynthesis (LPS) and grain yield of wheat [Triticum aestivum L.] were examined under irrigated and non-irrigated conditions in Cerrados, a semi arid region in Brazil. Twelve Brazilian, five Mexican and two Japanese cultivars were used in this project. The plants were grown under low planting density to elucidate the relationship between LPS and the potential yield of an individual plant. Brazilian cultivars ranked high in LPS, followed by Mexican and Japanese cultivars under non-irrigated conditions, although there were practically no differences in LPS among these three groups of cultivars in irrigated conditions. The LPS showed a significant positive correlation with grain yield (r = 0.63**) and dry matter yield (r=0.73**) per plant in non-irrigated conditions. However, LPS showed neither correlation with grain yield nor dry matter yield per plant in irrigated conditions. The present results suggests that PLS could be a breeding criteria to increase the yield per plant under soil water deficit conditions.