The effect of fluctuating substrate salinity on the yield and flag leaf photosynthesis of wheat.

Abstract

The effects of constant and fluctuating substrate salinity on flag leaf photosynthesis and grain yield of wheat were investigated. Plants exposed to salinity fluctuating around a mean integrated value of 25 mol m-3 NaCl (0-50 mol m-3) and around 50 mol m-3 NaCl (25-75 mol m-3) had yields 36 and 38% higher, respectively, than those receiving the corresponding constant salinity. Plants treated with salinity fluctuating from 50-100 mol m-3 NaCl had a 14% lower yield than those receiving 75 mol m-3 NaCl. Flag leaf photosynthesis did not vary between treatments and during salinity fluctuations, suggesting that differences in flag leaf longevity caused the observed differences in yield. Results suggest plants grown under constant salinity are unlikely to behave as those in field situations, where fluctuating rather than constant salinity occurs.