The response of some varieties of soybean Glycine max L. to spraying ascorbic acid on the characteristics and components of yield

The study was conducted at the Research Station of the Field Crops Department, College of Agriculture, Tikrit University, during the summer season of 2024, with the aim of evaluating the effect of foliar application of ascorbic acid on the growth and yield of three soybean cultivars (Shaimaa, Lee, Laura) using four concentrations (0, 50, 100, 150 mg L-¹). The experiment was laid out in a randomized complete block design (RCBD) under a split-plot arrangement with three replications. The results revealed that foliar spraying with 150 mg L-¹ of ascorbic acid significantly enhanced several traits, including plant height (54.06 cm), leaf area (1982.99 cm² plant -¹), number of pods (134.23 pods plant-¹), 500-seed weight (68.44 g), and total yield (2.30 t ha-¹). Among the cultivars, “Shaimaa” outperformed the others in terms of leaf area (2006.66 cm² plant-¹), number of pods (133.62 pods plant-¹), 500-seed weight (67.46 g), and recorded the highest total yield (2.30 t ha-¹). Moreover, the interaction between cultivars and ascorbic acid concentrations had a significant effect, as the combination (Shaimaa × 150 mg L-¹) produced the highest total yield (2.48 t ha-¹), while the combination (Lee × 0 mg L-¹) recorded the lowest values for several traits. These findings indicate the efficiency of foliar application of ascorbic acid, particularly at 150 mg L-¹, in improving growth and yield traits of soybean, with the best performance achieved by the Shaimaa cultivar.