Effect of Zn as soil addition and foliar application on yield and protein content of wheat in alkaline soil

Abstract

Zinc (Zn) deficiency in plant tissues is a reflection of both genetic and soil-related factors and is the most widespread problem in cereal crops worldwide, resulting in severe losses in the yield and nutritional quality. Developing cost-effective and quick solutions to Zn deficiency is, therefore, highly important. An experiment was conducted during 2009 − 2010, to assess the effects of various modes and concentrations of applied Zn on wheat yield and nutritional quality grown in alkaline soils. Both soil addition and foliar spray of ZnSO4 significantly increased grain yield, 1000 grain weight and grain protein content, while its effect on biological yield and grain protein composition was not significant. Foliar spray of 0.5 % and 1.0 % ZnSO4 increased grain yield by 10 and 18.8 %, respectively while its soil application at the rate of 5, 10 and 15 kg ha-1 increased grain yield by 18, 32 and 41%, respectively over the control. The treatments receiving ZnSO4 as 5 kg ha-1 soil + 1.0 % foliar, 15 kg ha-1 soil + 1.0 % foliar and 5 kg ha-1 soil + 0.5 % foliar application recorded 29.5, 29.0 and 27.5 % higher protein contents, respectively over the control. Comparing the value cost ratios (VCR) for the treatments showing higher grain yield and protein content, the VCR for 5 kg ha-1 ZnSO4 as soil + 1.0 % ZnSO4 as foliar (10.23) was three times higher than the VCR for 15 kg ha-1 ZnSO4 as soil + 1.0 % ZnSO4 as foliar (3.46), thus confirming the superiority of the former over the latter in terms of effectiveness. The results further revealed that despite presumably sufficient native Zn concentration in the soils under study (1.95 mg kg-1), the crop responded positively to Zn treatment and therefore the Zn level of sufficiency (1 mg kg-1) should be reconsidered in accordance with the nature and type of soils.