Physiological assessment of drought tolerance in wheat (Triticum aestivum L.) varieties under moisture stress conditions

Drought is one of the major limiting factors in wheat production in Pakistan. Five commercial wheat varieties; Chakwal-97, Inqilab-91, Margalla-99, NR-234 and Wafaq2001 were grown in pots in glasshouse. Plants were subjected to three consecutive drought cycles at tillering, pre-anthesis and milky growth stages by withholding water till leaf rolling started. Measurements of physiological response to the drought stress, i.e., changes in relative water content, proline, superoxide dismutase, membrane stability index, yield and yield components were made. Significant reduction in grain yield was observed in all the test varieties when drought was imposed at any growth stage. The reduction was highest (39-64%) when stress was imposed at pre-anthesis followed by tillering growth stage. The wheat variety Wafaq-2001 and Inqilab-91 performed better by giving high yield and produced greater numbers of filled seeds per spike as compared to other varieties. Under water stress, proline contents were higher in the drought-tolerant cultivar Wafaq-2001. The same variety showed higher relative water content, membrane stability index and antioxidant enzymes (SOD) activity under drought stress conditions.