Osmotic stress and nitrogen metabolism of two groundnut (Arachis hypogaea L.) cultivars

The water status and nitrogen metabolism of the groundnut (Arachis hypogaea L.) cultivars, M-13 and M-145 were examined during a period of water stress and recovery. 10 day old seedlings, grown in controlled environment were exposed to solutions of polyethylene glycol (MW 6000, osmotic potential, −0.5 or −0.8 MPa = −5 or −8 bars) for a week when the stress was relieved by replacing the PEG solution with a nutrient solution. Relative turgidity, total protein and free amino acid concentration and nitrate reductase activity were measured during the period of stress and recovery. Cultivar M-13, despite its lower relative turgidity during stress, was better able to preserve its protein concentration and nitrate reductase activity, and recover to a normal state within three days of the relief of stress. M-145, on the other hand, failed to recover within this period. The results are discussed in the light of the known performance of the two cultivars in the field under drought conditions