Effects of different microbial agent applications on the growth and quality of saffron (Crocus sativus L.) cormels

Abstract

Saffron (Crocus sativus L.) is a bulbous flower whose dried stigmas are used as a herbal medicine and as a spice. Saffron is cultivated worldwide, but corm degradation is an important factor affecting its yield and quantity. This study investigated the effects of three different microbial agents (Bacillus megaterium, Brevibacillus laterosporus, Paenibacillus mucilaginosus) on the growth and quality of saffron cormels. Both the weight and circumference of the cormels were significantly increased in response to microbial agent treatment. Measurements of the physiological and biochemical characteristics of the cormels as well as the flowering traits showed that the starch and protein contents as well as the flowering rate and stigma yield increased significantly after the application of the three microbial agents. Analyses of soil physicochemical properties and microbial populations revealed increases in the soil potassium content and a significant alteration in the soil microbial community structure in response to treatment. Our results showed that the application of three microbial agents enhances the growth, nutritional status and health of saffron cormels and improves the soil environment during saffron corm cultivation. Paenibacillus mucilaginosus also increased the accumulation of crocins and picrocrocin in stigmas. Our results provide the theoretical and practical knowledge needed to reduce corm degradation and to improve saffron corm cultivation.