Growth and Flowering of Saffron (Crocus sativus L.) with Three Corm Weights under Different LED Light Qualities

Saffron (Crocus sativus L.) is a flowering plant whose dried stigma is an expensive and well-known spice. The major goal in saffron cultivation is to improve flower quality and yield. The present research aimed to understand the influence of LED light quality on the growth and flowering of saffron and provide valuable guidance to explore modern techniques to promote flower and stigma yield. The growth characteristics, flowering characteristics, hormone and nutrient content, and stigma quality and value were determined at three different corm weights (20-25 g, 25-30 g, 30-35 g per corm) under six LED light qualities [white (control, CK); monochromatic blue light (B); monochromatic red light (R); red and blue light at 1:2 ratio (R1B2); red and blue light at 1:1 ratio (R1B1); red and blue light at 2:1 ratio (R2B1)]. Monochromatic red light reduced corm biomass loss, accelerated apical bud growth, enhanced flower size and number, and advanced flowering. Monochromatic red light significantly increased the indole-3-acetic acid (IAA), soluble protein (SP), and zeatin riboside (ZR) levels in the mature corms compared with CK. Besides, red light demonstrated the highest hormone and nutrient content for the 30-35 g corm weight. Furthermore, monochromatic red light improved stigma yield (total dry weight), total crocin production, and the practical value ratio of saffron. The present study's observations indicate that monochromatic red light promoted saffron growth, advanced flowering, and increased stigma yield by regulating the corm phytohormones and enzyme activity. The study provides valuable guidance to explore modern techniques to promote saffron flower and stigma yield.