Effects of humic acid and corm density on saffron yield and yield components in the second year

The effects of application of humic acid and planting density on vegetative and reproductive characteristics of saffron were evaluated under field conditions. Treatments were four levels humic acid (0, 5, 10 and 15 kg.ha-1) and three density plantings (50, 75 and 100 corm.m-2). This experiment was carried out as a factorial based on randomized completely block design with three replications in the research farm of Birjand University, Iran, during the cropping year 2015-2016. The results showed that humic acid levels improved the corm vegetative indices (total weight of corm, fresh and dry weight of corm). The highest total weight of corm (23.09 g.plant-1) was obtained in with 5 kg.ha-1 humic acid. The results also showed that humic acid improved the saffron flower characteristics (flower number and fresh total yield, stigma fresh and dry yield) in the second year. The highest stigma fresh (1.35 g.m-2) and stigma dry (0.23 g.m-2) yield were obtained in plants treated with 10 kg.ha-1 humic acid while the lowest values were recorded in the control group. Application of different levels of planting density had a positive effect on flower number and fresh total yield, stigma fresh and dry yield in the second year of experiment. The highest of these characteristics were observed in planting density of 100 corm.m-2. Application of different levels of planting density and humic acid had a positive effect on the stigma length and stigma fresh yield. Thus, the results showed that 5 kg.ha-1 of humic acid and 75 corm.m-2 planting density have a significant impact on vegetative and reproductive characteristics of saffron.