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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.

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Humic acid as an organic acid produced by humus and other natural resources can improve nutrients absorption and seed yield. In order to study the effect of granular humic acid and foliar application of compost tea and vermiwash on nutrient absorption, chlorophyll content and seed yield of safflower (Carthamus tinctorius L.), an experiment was conducted as a factorial experiment based on randomized complete block design with three replications in agricultural research farm at Vali-e-Asr University of Rafsanjan. Treatments included of soil application of humic acid (0, 500, 1000 and 1500 kg ha-1) and foliar spraying of vermiwash 1:10, vermiwash 1:20, compost tea and distilled water as control. Results indicated that humic acid application had significant effect on the zinc, nitrogen and phosphorus content of shoot, chlorophyll index and seed yield. On the other hand, compost tea foliar application significantly influenced zinc and copper content of shoot, chlorophyll content and seed yield of safflower. It seems humic acid application (1500 kg.ha-1) in soil along with compost tea foliar application was the best treatment for producing of seed yield and higher nutrition absorption, chlorophyll content in safflower.