Response of orange Saplings to spraying with brassinolide and add-ing organic fertilizer in some of vegetative and root growth charac-teristics

Abstract

The experiment was carried out at the Horticulture station in the Al-Hindiya district / Karbala governorate during the 2023 growing season, using a Randomized Complete Block Design (RCBD) with three replications. The study aimed to investigate the response of two orange Cultivars (Blood and Navel) to spraying with the growth regulator brassinolide at three concentrations (0, 0.3 and 0.6 mg L-1) and the addition of organic fertilizer (Humzinc) to the soil at three concentrations (0, 0.5 and 1 g L-1). The results showed the superiority of the Blood Cultivar over the Navel Cultivar in stem length, stem diameter, Leaves number, root length, and root volume, while the Navel Cultivar excelled in leaf area. Treatment with brassinolide at a concentration of 0.6 mg L-1 or the addition of organic fertilizer at a concentration of 1 g L-1 resulted in the highest significant increase in stem length, stem diameter, Leaves number, leaf area, root length, and root volume. Regarding the interactions between study factors, the binary and ternary interactions had a significant effect on improving vegetative and root growth Traits. The ternary interaction treatment (Blood Cultivar + brassinolide 0.6 mg L-1 + 1 g L-1) outperformed by giving the highest average increase in stem length (35.98 cm), stem diameter (7.993 mm), average Leaves number (117.66 leaves seedling-1), root length (120.67 cm), and root volume (52.33 cm3), while the treatment (Navel Cultivar + brassinolide 0.6 mg L-1 + 1 g L-1) significantly excelled in leaf area (38.57 cm2).