Influence of Foliar Spray of Mg, Boron, and Zn on Growth and Yield of Broccoli (Brassica oleracea var. Marathon)

Abstract

Broccoli (Brassica oleracea var. italica) is an important vegetable crop recognized worldwide for its high nutritional value and health-promoting properties. It is a rich source of vitamins, minerals, antioxidants, and dietary fiber, making it an important component of a healthy diet. However, the growth, development, and yield of broccoli can suffer when essential micronutrients are not sufficiently available to plants. Micronutrients such as magnesium, boron, and zinc play important roles in various physiological and biochemical processes, including photosynthesis, enzyme activity, cell division, flowering, and head development. To address micronutrient deficiency and improve broccoli productivity, we conducted a field study in Qalai Janan Khan Village, Behsood District, Nangarhar Province, Afghanistan, during the 2025 fall–winter season. The experiment evaluated the effects of foliar applications of magnesium, boron, and zinc at 100 and 200 ppm, along with an untreated control. The treatments were arranged in a Randomized Complete Block Design (RCBD) with three replications to ensure reliable comparison among treatments. Micronutrient application enhanced vegetative growth, improved plant development, and positively influenced flowering and head formation. Among all treatments, foliar application of zinc at 100 ppm produced the best overall performance, resulting in stronger plant growth, better leaf development, earlier flowering, larger heads, and higher marketable yield. The findings demonstrate that appropriate foliar micronutrient application can improve broccoli productivity under local growing conditions. Overall, foliar application of zinc at 100 ppm was the most effective treatment under the agro-climatic conditions of Nangarhar Province, Afghanistan.