Genetic variations in photosynthetic rate, pod yield and yield components in Spanish groundnut cultivars during three cropping seasons

► Wide genetic variability in P N, gs and difference between T air and T leaf were observed. ► Physiological traits were closely associated with each other. ► Ideotype suitable for cultivation under normal irrigation and water deficit conditions was proposed. ► Potential cultivars were identified after analyzing G × ← E interaction. ► Groundnut productivity may be increased by altering the stomatal conductance. Thirty Spanish groundnut ( Arachis hypogaea L.) cultivars were grown for three cropping seasons, i.e., for two consecutive rainy and summer, and one post-rainy, and evaluated for physiological, morphological and anatomical traits and yield components. Photosynthetic rate ( P N) was measured at full pod (R4) during rainy and post-rainy while at different reproductive growth stages during summer seasons. Response of cultivars to physiological traits differed significantly and cultivars belonging to high P N expressed higher g s and lower difference between leaf and air temperatures (Δ T) indicating that groundnut productivity could be increased by increasing g s. Among the reproductive growth stages, P N was higher during full pod (R4) and beginning seed (R5) in addition Δ T was least during this period. This indicated that Spanish groundnut is more close to the determinate type of growth habit and exhibited reproductive sink driven P N. Associations between morphological and physiological traits and yield components were established and potential trade-offs between various traits were identified. For example, associations between P N and total sink size ( r = 0.43**), weight of mature pods ( r = 0.45**) and harvest index (HI) ( r = 0.48**) were positive while association between P N and Δ T ( r = −0.60**), leaf temperature ( r = −0.47**), petiole length ( r = −0.50**), both leaflet length and width ( r = −66**) were negative. Among the sources of variation, environment was found most detrimental to influence the traits and among the physiological traits influence of environment was more on g s than the P N and Δ T. Similarly, environment has influenced pod yield more than reproductive sink size. Among all the traits studied, P N, g s, pod yield and HI contributed maximum to the observed variation. In conclusion, knowledge on physiological understanding in relation to P N and productivity and wide genetic variability among various traits, as reported in this study, could be utilized in developing new potential germplasm and designing ideotype for maki