Genetic analysis for transpiration efficiency and other physiological traits in cowpea [Vigna unguiculata (L.) Walp.]

摘要

Heterosis for transpiration efficiency (TE) and five other physiological traits was estimated in 36 hybrids produced through line X tester mating design. Maximum heterosis over mid parent (MP) was observed for water used per plant (CWT) (89.7 percent in TVX-944 X APC-546) followed by TE (67.7 percent in KBC-1 X APC-714). Significant positive heterosis over better parent (BP) was observed for net assimilation rate (NAR) (64.4 percent in TVX-944 X APC-689) followed by TE (52.8 percent in TVX-944 X APC-714). Significant negative heterosis over MP was observed for NAR (-57.4 percent in C-152 X APC-478) followed by CWT (-38.8 percent in KBC-2 X APC-478). Significant negative heterosis over BP was observed for NAR (-69 percent in C-152 X APC-478) followed by mean transpiration rate (MTR) (-49.6 percent in TVX-944 X APC-714). A significant inverse relationship between TE and MTR and positive relationship between TE and NAR suggested that genetic variation in TE manifested by mesophyll factors. Lack of correlation in F_1 hybrids between TE and NAR suggests that variability for TE in hybrids is predominantly controlled by stomatal, rather than mesophyll factors. Heterosis for yield, which in turn is dependent on contribution of these physiological traits, the crosses like TVX-944 X APC-478 and KBC-1 X APC-714 were selected for further evaluation trial to identify the desirable segregants in the water scarce condition.