Influence of the Duration of Favourable Moisture Between Droughts on Wheat

Abstract

Diverse effects of 3,6, 9 and 12 days of favourable moisture between two drought cycles on wheat (Triticum aestivum L. cv. Kalyan sona) have been reported here. The first cycle of drought imposed for a period of 10 days on separate sets of plants at 51, 54,57 and 60 days after sowing (DAS) caused comparable reductions in plant water potential ( tp plant), relative turgidity (RT%) and grain yield. All these plants were simultaneously subjected to a second cycle of drought at 73 DAS for a uniform period of 9 days. Observations on ti plant, RT, stomatal resistance and also contents of free amino acids, free proline and soluble protein, at the end of the second drought cycle and 48 h after irrigation, indicated that the adverse effects of water stress were more severe in plants which were given shorter (3 and or 6 days) compared to longer (9 and 12 days) periods of adequate soil moisture between two droughts. Changes in the activities of amylase, nitrate reductase, malate dehydrogenase and glucose-6-phosphate dehydrogenase generally revealed a similar trend. Notwithstanding a larger decline in grain yield under two, as compared to one cycle of drought, the grain yield was also depressed more under shorter (3 and 6 days) as compared to longer (9 and 12 days) period of adequate water supply between the stress events. Evidences provided here show that, among other factors, t he period of favourable moisture between droughts has a significant influence on metabolism and crop performance.