Effects of irrigation water salinity levels and Zn applicaton rates on wheat (Triticum aestivum L.) yield under field conditions of yazd province

The objectives of this field study were to evaluate the interactions between Zn nutrition and the salinity of irrigation water and their effects on wheat growth. The treatments, four zin sulphate application rates (0, 20, 40 and 80kg ha-1) and three irrigation water qualities (1.88, 7.22, 14.16dS/m), were arranged in a compelet randomized block, split plot design with three repelications. The results showed that wheat grain yield at irrigation water salinities of 1.88 and 16.14dS/m responded similarly to zinc application rates and followed the quadratic non-linear regression model. The maximum grain yield for plants irrigated with both irrigatin water salinity of 1.88 and 16.14dS/m were found at zinc sulphate application rate of 25kgha-1. In addition, wheat grain yield response to salinity stress at zinc sulphate rates of 0, 20 and 40kgha-1 was similar and followed linear regression model. As with increasing Zn application rate the decline per unit slope decreased, it can be concluded that zinc increases the salinity tolerance of wheat. Interestingly, wheat grain yield response to salinity stress at highest Zn application rate of 80kgha-1 followed the quadratic regression model. This observasion, also, proves that wheat response to salinity stress depends on soil fertility level. The results of this experiment showed that wheat response to salinity stress depends on soil fertility level (Zn application rate). In additions, the results showed that with increasing irrigation water salinity from 1.88 to 16.14dS/m the grain yield decreased from 6.5 to 3.5 tonnes/ha but ZnSO4 requirement was not changed.