Effect of Foliar Application of Castor Oil and NAA on Physicochemical Properties of Apple (Malus pumila Mill.) Fruits

10.58928/ku26.17307
Volume 17, Issue 3
Summer 2026
Page 58-62

Document Type : Research Paper

Authors

1 department of horticulture and landscape design, faculty of agriculture, university of kirkuk, kirkuk, Iraq

2 department of feild crops, faculty of agriculture, university of kirkuk, kirkuk, Iraq

3 Siirt University

Abstract
This study aimed to evaluate the effects of foliar application of castor oil and naphthalene acetic acid (NAA; commercially known as Stavals) on the physicochemical characteristics of apple (Malus pumila Mill.) fruits under Iraqi environmental conditions. The experiment was conducted during the 2024 growing season using a randomized complete block design (RCBD) with three replicates. Twenty-seven uniform trees were subjected to nine treatments, including individual and combined applications of castor oil (3% and 5%) and NAA (30 and 60 mg L⁻¹). The results demonstrated that foliar treatments significantly (P ≤ 0.05) improved key physical attributes of the fruits. In particular, the combined application of 5% castor oil and 60 mg L⁻¹ NAA resulted in the highest fruit moisture content and juice percentage, along with a substantial reduction in fruit cracking compared to the control. These improvements are likely attributed to enhanced cell wall extensibility induced by NAA and reduced transpiration due to the film-forming properties of castor oil. Conversely, chemical characteristics such as total soluble solids (TSS), anthocyanin content, and vitamin C showed a decreasing trend under most treatments, although the differences were not consistently significant across all treatment combinations. This reduction may be explained by dilution effects associated with increased water content in fruit tissues, In conclusion, the combined foliar application of castor oil and NAA represents a promising strategy for improving the physical quality and reducing physiological disorders of apple fruits. However, further optimization is required to achieve a balance between enhancing physical traits and maintaining chemical and nutritional quality.

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Subjects
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