Effect of biological factors on some growth characteristics of the Crocus sativus L. plant

Resumo

Crocus sativus L. is an autumn-flowering species belonging to the Iridaceae family. This study was conducted under greenhouse conditions at the Plant Production Technology Department, Agricultural Technical College, Northern Technical University, to evaluate the effects of the environmentally friendly biological agents Trichoderma harzianum T-22 and Bacillus subtilis on vegetative growth, flowering, stigma production, enzymatic activity, and corm yield of saffron using two application methods. Significant differences were observed between biological treatments and the untreated control. Corm immersion with T. harzianum T-22 promoted the earliest vegetative bud emergence (17.56 days). The same fungal treatment also produced the tallest plants, reaching 8.75 and 7.40 cm depending on the application method, whereas untreated plants reached only 3.42 cm. Both fungal and bacterial treatments significantly reduced the time required for flower bud emergence, with T-22 showing the shortest periods (89.77 and 89.81 days). Corm immersion with fungal and bacterial agents also shortened the time to first flower opening to 125.6 and 126.1 days, respectively. Fresh and dry stigma weights were significantly higher in biologically treated plants than in the control, which recorded only 0.021 and 0.002 g, respectively. Peroxidase activity in saffron leaves was highest in plants treated with T-22, reaching 0.096 unit min-¹ g-¹ fresh weight. Biological treatments also significantly increased corm number, corm fresh weight, cormlet number, and cormlet fresh weight compared with the control. Overall, T. harzianum T-22 and B. subtilis improved saffron growth, flowering, physiological activity, and yield under greenhouse conditions.