Effect of foliar application with potassium and biozyme on growth and yield of cauliflower (Brassica oleracea var botrytis)

This study was conducted during the 2021–2022 agricultural season at the Research Station (A) of the College of Agricultural Engineering Sciences, University of Baghdad, Iraq, to evaluate the effect of foliar application of potassium sulfate, Biozyme, and their combinations on the vegetative growth and yield of cauliflower (Brassica oleracea var. botrytis, cv. Solid Snow). The experiment was arranged as a factorial randomized complete block design (RCBD) with three replications, including four concentrations of potassium sulfate (0, 3500, 5000, and 6500 mg L⁻¹) and three concentrations of Biozyme (0-, 0.45-, and 0.70-mL L⁻¹). Potassium sulfate was applied four times at 15-day intervals, and Biozyme was applied twice during the vegetative growth stage. Results showed that spraying with potassium sulfate at 6500 mg L⁻¹ significantly increased plant height (69.14 cm), number of leaves (28.08 leaves plant⁻¹), leaf area (8535.4 cm² plant⁻¹), and dry weight (286.9 g) compared with the control. Potassium sulfate at 5000 mg L⁻¹ recorded the highest flower head weight (1.495 kg) and total yield (49.83 t ha⁻¹). Foliar application of Biozyme at 0.70 mL L⁻¹ significantly enhanced all measured traits, including plant height (69.81 cm), head diameter (21.89 cm), head weight (1.511 kg), and total yield (50.39 t ha⁻¹). The interaction between 5000 mg L⁻¹ potassium sulfate and 0.70 mL L⁻¹ Biozyme (K2B2) produced the highest head weight (1.585 kg), head diameter (22.92 cm), and total yield (52.84 t ha⁻¹). These findings indicate that combined foliar application of 5000 mg L⁻¹ potassium sulfate with 0.70 mL L⁻¹ Biozyme can be recommended to improve cauliflower growth and yield under the environmental conditions of Iraq. Keywords: Brassica oleracea var. botrytis, foliar feeding, potassium sulfate, Biozyme, yield, vegetative traits.