Physiological analysis of leaf photosynthesis of backcross-derived progenies from soybean (Glycine max (L.) Merrill) and G. tomentella Hayata

Abstract

ABSTRACT The enhancement of leaf photosynthesis is an enticing aspect for increasing crop seed yield. Using wild-related species in soybean breeding can be a potential source to enhance leaf photosynthesis. Two backcross-derived progenies of soybean (Glycine max) with Glycine tomentella Hayata were evaluated in terms of gas exchange, biomass, and seed yield. The gas exchange parameters along with Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) content, and leaf nitrogen content (LNC) were measured from flowering stage up to seed initiation stage. Results revealed significant increases of net photosynthetic rate (Pn), mesophyll activity (Pn /Ci ), seed yield, and total aboveground dry weight (TDW) in progenies relative to Dwight. We observed significantly higher specific leaf weight (SLW) in progenies and was strongly correlated with Pn (r = 0.86***). There was no significant difference between Dwight and the progenies in stomatal conductance (gs ), but Dwight, in fact, had higher intercellular CO2 concentrations (Ci ). It indicates that increases in Pn were associated with improved Pn /Ci . These findings suggest the potential use of soybean wild relatives in breeding to enhance soybean leaf photosynthesis.