Effects of Different Corm Densities and Bed Types on Flower Yield Components of Saffron (Crocus sativus L.)

Saffron is among the most precious agricultural and medicinal plants of the world and has a specific placement in Iran exports. In Iran total cultivation area was 93000 ha in 2017 that from which about 96% devoted to two main provinces of saffron production including Khorasan-Razavi and South Khorasan with total production of 351 ton saffron. Saffron has unique characters including low water requirement, saffron irrigation in times that other crops do not need, farm utilization for some years, ease of transportation, lack of need to special machinery and complex technology, high capacity to use labor in time of picking flowers, occupation and in the end prevention from immigration and exchange income that make this crop becomes superior in those regions that lack of industrial perspectives and having water limitations. Organic fertilizers have effective role in saffron production including physical improvement of saffron soil, temperature relief, penetration improvement, porosity increase, and soil reducdtion in hardiness, and cause to saffron flowering. Several factors like climate, diseases, irrigation, storage, planting date, chemical and biological fertilizers and animal manure are very effective in saffron quantity and quality. Saffron yield depends on several factors like soil, crop density, planting method, corm size, geographical location, climatic factors like temperature fluctuations specially in time of flowering, rate of rainfall, cultural management and utilization period. The aim of this study was to determine possible effects of corm density and bed type on flower yield components and stigma yield of saffron.
In order to evaluate effects of corm density and bed type on reproductive characters, yield components of flower and saffron stigma an experiment was conducted in the form of factorial as RCBD with three replicates at the research farm of Khorasan Science and Technology Part (KSTP) during growing season of 2010-2011.The treatments under study were density with three levels of 50,100,150 corms per m2 and five bed types of 10 t.ha urban compost, 30 t.ha decayed cow manure, 20 t.ha mushroom bed residues,10 t.ha wheat straw, and control that were applied in planting time. Traits measured were number of flowers, fresh and dry weight of flowers, fresh and dry weight of stigma, fresh and dry weight of style of saffron. Statistical analysis of the first year of data was done with SAS software and mean comparisons were as DUNCAN multiple range test at 5% level with MSTAT-C.
Results showed that corm density had significant effect on all traits under study at p≤0.01 but effect of bed type was only insignificant on number of flowers .m-2 and in other traits were significant at p≤0.01. Increasing corm density from 50 to 150 corms.m-2 increased flower number from 16.8 to 46.8 . m-2 (about 179%) and fresh weight by 177 and stigma dry weight by 155%.The highest fresh and dry weight of stigma style were found in wheat straw that were 14.43 and 2.59 kg.ha, respectively. Interaction between corm density and bed type was not significant in all traits under study.Variation of flower number .m-2 had high correlation with corm density.m-2 that shows trend of increasing flower number due to increasing corm number.
Therefore, it is concluded that for production of more flowers and dry weight of stigma in the first year corm density of 150 corms.m-2 and bed type of wheat straw is recommended.Saffron yield in the first year of cultivation is not economical and it seems that by using high density planting it almost compensates for low yield at the first year.Recently, farmers are willing to apply high corms for planting saffron farms. Saffron is an organic crop and preparing beds with organic fertilizers specially wheat straw due to its improvement of environmental conditions have positive effect in saffron yield and environmental improvement.