Differential accumulation of osmolytes in 4 cultivars of peanut (Arachis hypogaea L.) under drought stress

The study investigates the differential accumulation of osmolytes and their contribution to osmotic adjustment in leaf tissue of peanut under drought stress. Plants of four peanut cultivars, obtained from ICRISAT, with varying degrees of drought tolerance were subjected to 10, 15, and 20 days of drought stress by withholding irrigation to 20-day-old seedlings. Leaf samples were collected on 31st, 36th, and 41st days from these stressed plants along with their respective controls. The results indicated that ICGV 91114 was the most drought-tolerant variety followed by ICGS 76 and J 11, while JL 24 was the most drought susceptible. The leaves of ICGV 91114 maintained higher RWC and chlorophyll pigments under water stress compared to JL 24. The contents of all the biochemicals were found to be the maximum in ICGV 91114 and least in JL 24 during stress periods. Drought induced increase in the contents of TSS and TRS were significantly higher in ICGV 91114 under 15 days of water stress compared to the other three varieties and stress periods, while TLP, total free amino acids and total proline were higher in 20-day-old stressed plants of ICGV 91114 and the lowest in 10-day-old stressed plants of JL 24. In the control plants of all four varieties, there was a steady increase in the contents of all these biochemicals with an increase in the age of the plants. The results suggest that osmolytes act as important compatible solutes to maintain osmotic balance, to protect cellular macromolecules, and scavenge free radicals under water stress conditions.