Effect of Humic Acid Addition and Urea Foliar Spraying on Shoot Characteristics and Chemical Content of Olive Sapling Cv. Khistawi

Abstract

The experiment was conducted in the lath house belonging to the Department of Horticulture and Landscape Gardening, College of Agriculture, Anbar University, from 1/3/2022 to 15/11/2022 to determine the effect of soil application of humic acid at three levels (0, 10, 15 g sapling−1), respectively, and foliar spray of urea fertilizer at three concentrations (0, 10, 15 g L−1), respectively, and their interaction on the vegetative growth characteristics and leaf mineral content of Khistawi olive saplings. The results showed a positive effect of adding humic acid on most of the vegetative and characteristics and mineral content of the leaves. Adding (15 g sapling−1) resulted in a significant superiority in stem diameter, leaf area, new shoot lengths, percentage of nitrogen, chlorophyll content, carbohydrates, and leaf dry matter, with 4.236 mm, 5.190 cm2, 7.684 cm, 1.824%, 76.739 mg 100 g−1, 7.094%, 47.878% respectively compared to the control treatment. Foliar spray of urea fertilizer at concentration (15 g L−1) resulted in a superiority of the mentioned characteristics above when adding humic acid, reaching 4.530mm, 5.607 cm2, 8.066 cm, 1.844%, 77.578 mg 100 g−1, 7.190%, 48.126% compared to the control treatment. The interaction between the studied factors showed a similar behavior to the individual factors for all studied characteristics.