Effects of Zn rates and application forms on protein and some micronutrients accumulation in common bean (Phaseolus vulgaris L.).

In order to investigation the effects of Zn rates and application forms on protein and element contents (Fe, Cu, Mn, N and Zn) in bean plant, an experiment was conducted as a factorial based on completely randomized design at greenhouse conditions during 2006. Treatments were included zinc rates in 4 levels (10, 20, 30 and 40 mg Zn kg(-1) soil(-1) in ZnSO4 source) and 3 application forms (soil application, seed pelleting and foliar spraying). Results showed that Zn rates had significant effect on accumulation of Zn, Cu, Mn and N in bean leaves. Nitrogen accumulation in leaves reduced with increasing of zinc in the soil. Among Zn application forms, spray application had the highest accumulation of Fe, Zn and Mn in leaves (423.17, 282.89 and 88.17 mg kg(-1), respectively). The highest Zn content in seed was observed in 20 and 40 mg Zn kg(-1) soil(-1) levels (46.39 and 45.62 mg kg(-1), respectively). Meanwhile, all treatments of Zn (both rate and application) had not significant effects on Cu and Mn accumulation in bean seeds. According to interaction effects between Zn rates and application forms, the highest Fe content in seed was observed when 40 mg kg(-1) soil(-1) of Zn was applied as foliar spraying. The seed protein content nearly was stable while Zn levels was increased from 20 to 40 mg Zn kg(-1) soil(-1). Grain yield had significant correlation to zinc and Cu of leaves but, biomass had significant and negative correlation to Zn content of leaves at p < 0.05% probability levels.