Study on effects of foliar spraying and soil split application of humic acid on vegetative characteristics and flower yield of saffron (Crocus sativus L.)

The most expensive medicinal spicy plant in the Middle East countries is saffron (Crocus sativus L.) Saffron is one of the most valuable indigenous plants and herbs, spice in the world. Saffron is prepared from dried, bright red stigma and its value is determined by the color compounds, carotenoids, crocin, and other crocetinglocosyl ester, slightly bitter flavor, picrocrocin, and pleasant aroma, safranal Application of organic material is one-main factor for acheiving maximum yield of saffron plants. The aim of this study was to investigate effects of soil and foliar application of humic acid on vegetative and reproductive characteristics of saffron. This experiment was carried out as a factorial based on randomized completely block design (RCBD) with three replications in research farm of University of Birjand, Iran, during 2015 - 2016 growing season. The first factor is the humic acid type of use (soil and foliar application) and the second factor dose levels (0, 5, 10 and 15 kg.ha-1). The measured indices were included of leaf characteristics (leaf length, fresh and dry weight), corm characteristics (corm number, total weight, cormel weight and diameter) and flower characteristics (flower number and fresh total yield, average stigma length, stigma fresh and dry yield). Results showed that, humic acid type of use improved the leaf growth indices (leaf length, fresh and dry weight) and corm growth indices (cormel weight and diameter). The highest these indices were obtained in the humic acid soil application. Also, results showed that flower reproductive characteristics (flower number and fresh total yield, stigma fresh and dry yield) were influenced by humic acid type of use.The highest stigma fresh (0.781 g.m-2) and dry (0.147 g.m-2) yield were obtained in humic acid soil application. Humic acid concentration improved the leaf growth indices (leaf length, fresh and dry weight) and corm growth indices (cormel weight and diameter) and flower reproductive characteristics (flower number and fresh total yield and stigma fresh and dry yield).The highest flower fresh total yield (18.201 g.m-2) were obtained in plants treated with 10 kg.ha-1 humic acid. While the lowest values was recorded in the control. Interactive effects of these factors were effective on leaf length, flower number and stigma dry yield.The highest stigma dry yield (0.158 g.m-2) and flower number (48.833 per.m-2) were obtained in plants treated with 10 kg.ha-1 humic acid soil application. Thus, humic acid increased vegetative and reproductive saffron characteristics and soil application than the spray was more effective role in these characteristics.That, of 10 kg.ha-1 humic acid soil application was increased stigma yield of saffron.