Abstract

Groundnut (Arachis hypogaea L.) is an important oil seed crop mainly grown as rainfed crop. Due to erratic rainfall and frequent drought during the crop growth period, groundnut yields are generally low and unstable under rainfed conditions. Drought during critical crop growth stages is crucial for yield in groundnut varieties. But tolerant genotypes may give better yield due to maintenance of physiological responses that were triggered during drought. The experiment was conducted in the Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore during 2015-2016 to study physiological characters responsible for improving yield of different groundnut genotypes viz., CO 7, COGn 4, TMV 7 and TMVGn 13 under water stress at different flowering phases viz., pre flowering drought (PFD) during 15- 30 DAS, flowering drought (FD) during 35-50 DAS and post flowering drought (PoFD) during 75-90 DAS by withholding irrigation and control was also maintained with watering up to field capacity for comparison. Observations on various physiological parameters viz., leaf area, root length, relative water content, osmotic potential and leaf gas exchange parameters including, photosynthetic rate, transpiration rate and stomatal conductance were studied during stress and recovery period. Among the treatments, the plants under PFD performed better in recording higher value of physiological parameters under stress and recovered quickly. The variety, CO7 was found to perform well under all stages of stress followed by TMV 7, TMVGn 13 and COGn 4 with respect to physiological parameters and yield.

Keywords: Leaf area, Root length, Relative water content, Osmotic potential, Gas exchange parameters