Effects of foliar spraying humic acid on some morphological characteristics and flower yield of saffron (Crocus sativus L.)

The effects of application of humic acid on quantitative and qualitative characteristics of saffron were evaluated under field conditions. Treatment was of four levels of humic acid (0, 5, 10 and 15 l.ha-1) This experiment was carried out as based on randomized completely block design with three replications in research farm of Birjand University, Iran, during growing season 2015-2016. Results showed that humic acid improved the leaf growth indices (fresh and dry weight of leaf) and chl a. The highest leaf fresh (0.116g.p-1) and dry (0.029g.p-1) weight were obtained in plants treated with 5 and 10 l.ha-1 humic acid while the lowest values were recorded in the control. Also results showed that humic acid improved the corm growth indices (corm number and total fresh, cormel average weight and diameter). Stigma fresh and dry yield were influenced by humic acid treatments in second year of study. The highest stigma fresh (0.700g.m-2) and dry (0.029g.m-2) yield were obtained in plants treated with 5 and 15 l.ha-1 humic acid. While the lowest values (0.267 and 0.022 g.m-2) were recorded in the control. But, no significant difference was found in flower number and fresh total yield. Thus, results showed that application of 5 l.ha-1 humic acid useful to improve vegetative and reproductive characteristics of saffron.