Effect of concentration and frequency of silica foliar application on quantitative and qualitative characteristics of saffron

This research was carried out as factorial experiment basis on randomized block design with four replications on a three-year saffron farm in Mashhad at 2017/2018 crop year. The experimental factors were different concentrations of silica (0, 0.3, 0.5, 0.75, 1, 1.2 and 1.5 lit/ha) and the number of spraying times (Once, twice and three times). Silica spraying (with Crapsil brand) was performed on February 6, March 1 and March 6, 2017.The results showed that the main effect of silica, the number of sprays and their interaction on all studied traits were significant. Mean comparisons of the experimental factors revealed that at the concentration of 1.2 lit/ha silica and two times of spraying, the highest number of flowers per plant(693 flowers), leaf dry weight(3.56 gr/plant), fresh weight of corm(67.25 gr/plant), stigma length(3.8 cm), fresh and dry weight of stigma(1656.5 and 14.39 kg/ha respectively),Safranal (33%) and crocin (192.75%) obtained. The highest amount of picrocrocin (66.35%) was obtained at the concentration of 1.5 lit/ha and two times of spraying. Therefore, the application of silica with the concentration of 1.2 lit/ha in the two stages of spraying was the best treatment and was able to increase the number of flowers per plant, fresh weight of corms and dry weight of stigma 26.5, 106 and 21.2 percent, respectively compared with the control treatment.