Zinc and Boron Fertility to Optimize Physiological Parameters, Nutrient Uptake and Seed Yield of Sunflower

Field research was conducted at Students Farm, Sindh Agriculture University, Tandojam, Pakistan, during 2005 and 2006. The sunflower variety HO-1 was treated with 0-0, 101.5, 10-2, 15 -1.5, 15-2.0, 201.5 and 202.0 Zn-B kg ha. A basal dose of N, P, and K was applied at the rates of 90, 45 and 45 kg ha respectively across Zn-B treatments. The increase in Zn and B fertility from 10-1.5 to 20-2 kg ha increased physiological parameters, nutrient uptake and seed yield of sunflower. The maximum yield response was noted when Zn and B were applied at the rates of 15 and 1.5 kg ha respectively, beyond this level, no further increase were noted in any sunflower traits. Under this optimal Zn -B treatments, sunflower recorded higher dry matter, leaf area index, leaf area duration, crop growth rate and net assimilation rate all measured at flowering stage. Under the chosen macronutrient fertility level on this farm, sunflower growth and yield was optimized with micronutrient levels of 15 kg ha Zn and 1.5 kg ha B.