Interrelationship between Leaf Gas-Exchange Characteristics,Area Leaf Mass,and Yield in Soybean (Glycine max L. Merr) Genotypes

Variability in leaf gas-exchange traits in thirteen soybean (Glycine max L. Merr) genotypes was assessed in a field experiment conducted at high altitude (1 950 m). Leaf net photosynthetic rate (P^N) exhibited a high degree of variability at all the growth stages studied. P_N and other gas-exchange parameters exhibited a seasonal pattern that was similar for all the genotypes. P_N rate was highest at seed filling stage. P_N was positively and significantly associated with aboveground dry matter and seed yield. The area leaf mass (ALM) exhibited a strong positive association with leaf P_N, aboveground dry matter, and seed yield. The positive association between ALM, P_N, and seed yield suggests that this simple and easy to measure character can be used in breeding programmes as a surrogate for higher photosynthetic efficiency and eventually higher yield.