Effect of organic and chemical fertilizers application on relationships among growth indices, corm characteristics, flower related attributes and yield of saffron (Crocus sativus L.) ecotypes

This experiment was aimed to evaluate the effects of organic and chemical nutritions on flower related characteristics yield of saffron. Experiment was conducted using randomized complete block design with three replications at the research field of Shahid Bahonar University of Kerman, Kerman, Iran, during two growing seasons of 2015 and 2016. Nine saffron ecotypes (Bajestan, Estahban, Ferdows, Gonabad, Natanz, Qaen, Sarayan, Torbat-e Heydarieh and Zarand) were sown in different nutritional conditions (control (C): no fertilizer or amendment; 20 t.ha-1 compost (Com); and chemical fertilizers (CF): 46 kg ha-1 N and 13 kg ha-1 P2O5) in October 2015. Different traits, growth indices and corm characteristics in first growing season and flower related traits in second growing season were measured. Correlation analysis showed that the flower number (FN), fresh and dry flower weight (FFW and DFW), fresh stigma weight (FSW) and biomass duration (BMD) in all treatments were significantly and positively correlated with stigma yield (SY). The number of large corms (LCN) (more than 8 g) in CF and Com treatments showed significant and positive correlation with SY. The results of path analysis in control treatment showed that FN, corm mean weight (CMW), medium corms number (MCN) (4-8 g) had the highest direct effect (0.804, 0.907 and 0.502, respectively) on SY, whilst, the indirect effects was mainly through FN on SY. In Com treatment, FFW, DFW, FSW, main bud emergence percentage (MBEP) and sub bud number per corm (SBN) had the highest direct effects (0.799, 0.786, 0.406, 0.853 and 0.737, respectively) and corm characteristics and growth parameters had the highest indirect effects through these traits. In CF treatment, FN (0.801), FSW (0.561), LAI after critical stage (0.68), leaf dry weight (LDW) (0.649) and corm dry weight (CDW) (0.699) had the positive direct effect on SY. Effect of growth parameters and corm characteristics was mainly through FN on SY. Consequently, with proper nutrition, the number of flowers per unit area can be increase by improving the growth and the corm yield in the first year while reducing the effects of unknown factors, therefore improve the yield of saffron.