Abstract:

Data obtained from pot experiments was analyzed using a theoretical model of carbon isotope discrimination (△) for the effects of soil moisture and nitrogen phosphorus nutrient on carbon isotope discrimination. The results showed that △ increased with increasing soil relative water content (SRWC),with the highest △ values found between 60% and 70% SRWC. △ also increased with increasing phosphorus levels under conditions of water deficit. Correlation between water use efficiency (WUE) and △ could be dependent on the status of soil moisture and nutrient availability. Stable △ was negatively associated with WUE under water stress, and positively associated with WUE under optimum soil moisture. However, there was no correlation between △ and WUE under nitrogen deficit and correlations were significant when nitrogen was applied at 150 kg·hm-2.

Key words: Water use efficiency, Carbon isotope discrimination, Nitrogen and phosphorus nutrition, Wheat