Characterization of Oryza nivara introgression lines: A potential prebreeding resource to improve net photosynthetic ratein elite cultivars of rice

Photosynthesis is one of the fundamental processes influencing crop growth and productivity. In order to understand better the basis of variation in net photosynthetic rate (PN) and yield potential in rice, two backcross populations derived from Swarna × O. nivara were studied. Gas exchange and chlorophyll fluorescence measurements were taken at flowering stage and data on yield traits at harvest. PN was significantly correlated with stomatal conductance, transpiration rate, mesophyll conductance, carboxylation efficiency, yield per plant (YLDP), and dry mass in both populations. Ten introgression lines (ILs) showed higher PN than their parents. IL 230S showed highest PN with increased YLDP than the remaining ILs. Single marker analysis showed RM514 and RM48 was positively associated with PN and YLDP in popA, whereas RM204 and RM122 in popB. The first 4 principal components contributed 92 and 93% to the total genetic variation in each population, respectively.