The effect of zinc sulfate foliar application on yield and yield components of sunflower (Helianthus annuus L.) under drought stress

A field experiments was conducted at Sabzevar Agriculture & Natural Resources A field experiments was conducted to study the effect of zinc sulfate foliar application on yield and yield components of sunflower, Haysun-25 cultivar (Helianthus annuus L.) under drought stress at Sabzevar Agriculture & Natural Resources research center. This experiment was carried out (conducted, deleted) as split plot based on randomized complete block (RCB) design that main and subplot factors were drought stress levels [Non-stress, Moderate and High drought stress (6, 12 and 18 day’s irrigation interval, respectively] and foliar zinc applications (0, 5, 10 and 15‰), respectively. Foliar application of zinc was performed in 6 to 8 leaf stage of sunflower. Plant height, seeds per head, hollowness percentage seeds, 1000 seed weight, grain yield and biological yield were significantly affected by drought stress. Severe drought stress decreased plant height, seeds per head, 1000 seed weight and economic yield and increased percentage of empty seeds. The highest yield and yield components were related to foliar application with 15‰ concentration of zinc sulfate and the lowest one was related to the control. However, yield response to zinc sulfate foliar application was more in non-stress condition, but zinc sulfate with 15‰ led to decrease of negative effects of drought stress. Overall, the highest yield was obtained by spraying with concentration of 15‰ zinc sulfate and non-stress condition.