Effects of Different Foliar-applied Organic Fertilisers on Early Morpho-physiological Development in Forage Soybean [Glycine max (L.) Merr.] Varieties

Background: Due to the burgeoning interest in sustainable and eco-friendly agricultural practices, organic-based fertilizers have become increasingly pivotal in enhancing plant growth and physiological performance. Accordingly, this study evaluated the effects of vermicompost, seaweed and humic acid applications on the morpho-physiological development of Yemsoy and Yeşilsoy soybean varieties [Glycine max (L.) Merr.] cultivated for fodder production. Methods: The experiment was conducted in a randomized complete block design with four replications. Vermicompost, seaweed and humic acid were applied and plant height, leaf area, stem diameter, number of leaves, leaflet width and length and SPAD values were measured during three measurement periods. The applications were initiated at the V2 growth stage of soybean (two-leaf stage) and repeated at 15-day intervals, resulting in a total of three applications. The data were evaluated using analysis of variance (ANOVA). Result: ANOVA results showed that fertilizer treatments and measurement periods had statistically significant effects on all parameters at the 1% level (P less than 0.01). In the first measurement period, vermicompost produced the highest plant height, while seaweed increased leaf area by 82% compared to the control group. In the second period, vermicompost increased plant height by 52.2% in Yemsoy and 47.1% in Yeşilsoy compared to the control. During the third period, plant height reached approximately 50 cm and leaf number increased to 8.5-9 per plant under vermicompost application, representing the highest values among the treatments. Overall, vermicompost was the most effective treatment, providing a 38-80% improvement in vegetative growth parameters compared to the control. Seaweed enhanced stem and leaf structure, whereas humic acid resulted in a 12-30% increase compared to the control but remained less effective than the other treatments.