Evaluation of Characteristics Related to Photosynthetic Rate and Leaf Area Production in Mungbean Genotypes

Abstract

Characteristics related to photosynthetic rate and leaf area production of 63 mungbean (Vigna radiata (L.) Wilczek) genotypes collected from different Asian countries were evaluated in pot culture conditions. There were large genotypic differences in photosynthetic rates (Pn) and its related factors. Each of the variations was also quite large, but that of leaf conductance (Gl) was the largest. Pn was positively correlated with its related factors. Among them, mesophyll conductance (Gm) was the highest. The transpiration rate (Tr) of most of the genotypes was higher than that of other crops. Although there was a high correlation between Tr and Gl, Tr was saturated at over 0.75 mol·m^-2·s^-1 of Gl. As a result, genotypes with high Gl resulted in higher water use efficiency (WUE) compared with other genotypes. Based on Pn values, all the genotypes were classified into three groups, high Pn, medium Pn and low Pn. Genotypes belonging to the high Pn group had high values of related factors as compared with that of the medium and low Pn groups. Although the leaf area increasing rate (LIR) and mean area of the terminal leaflet (TLA) had a significant correlation with Pn, the leaf emergence rate (LER) did not. Specific leaf weight (SLW) significantly related with Pn. It is, therefore, considered that stomatal frequency which relates strongly to Gl, mean TLA, LIR and SLW, can be used as selection criteria for improvement of Pn in mungbean genotypes.