Effect of Foliar Application with Gibberellic Acid on Growth, Yield Components of Sesame and its Seed Oil Content

Howaida E. Abdel Kader*

Agronomy Department ، Faculty of Agriculture ، Assiut University، Assiut ، Egypt. Correspondence Author: howidaahmed10@gmail.com

DOI: 10.21608/AJAS.2026.451090.1586

© Faculty of Agriculture, Assiut University

Assiut Journal of Agricultural Sciences 57 (2) 2025 (27-44)

Abstract

The present investigation was carried out at field Experimental Station, Agric. Faculty., Assiut Univ., during the two successive summer seasons, 2023 and 2024 to evaluate the effects of foliar application of gibberellic acid at three times; 25 or 45 days once and twice at 25 and 45 DAS during growing season with concentrations of 0, 50, 100, and 150 ppm GA₃ on the growth, yield, and seed oil characteristics of sesame (Giza 32).

Results showed that highly significant differences in mean vegetative growth, yield components and seed oil yield in both seasons. Application of 150 ppm of GA₃ significantly increased plant height by (18.23 & 18.18%) and fruiting zone length by (31.61 & 31.65%) as well as, No. of capsules plant ^-1 by (28.86 & 28.90 %), capsule length by (5.86 & 11.22 %) and No. of seeds capsule^-1 by (19.84 & 19.87 %) in comparison to the control treatment in both seasons, respectively.

Spraying GA3 twice at 25 and 45 DAS induced significant values of all vegetative and yield components and seed oil yield in both seasons.

The most effective treatment which gave the highest values of yield and its components in both studied seasons was that of spraying 150 ppm GA3 twice at 25 and 45 DAS which recorded (1036.1 & 1152.5kg fed) for Seed yield, (514.3 & 572.1kg fed) for Oil yield and (20.75 & 23.08) for HI in both seasons, respectively

Microbial bioinsecticides are considered safer for the environment than traditional chemical pesticides. However, conducting the necessary studies to assess their impact on the honey bee is always essential. In this study, two bioinsecticides, Spinosad and Spinetoram, were examined and evaluated for their chronic exposure effects at sublethal concentrations on pollen consumption and the development of hypopharyngeal glands in two age groups: six-day-old and nine-day-old, caged honey bee workers under laboratory conditions. We found that Spinosad negatively affected pollen cumulative consumption and the glands’ volume, activity represented in histochemical structure, and nucleus area, with apparent effects observed in nine-day-old bees. As for Spinetoram, it did not affect pollen consumption or gland volume but showed a noticeable effect on gland histochemical structure and caused nucleus deformation in 9-day-old bees. Therefore, special attention needs to be paid to the sublethal effects of some microbial bioinsecticides on honey bees, and they should not be exempted from risk assessment analysis.

Sugar nutrition is essential for managing and maintaining healthy honey bee colonies, especially during nectar scarcity. This study aimed to evaluate the use of invert sugar as a nectar substitute, comparing its impact on the quality of stored honey and colony performance during overwintering to that of a traditional sucrose solution commonly used by beekeepers. Two separate field experiments were carried out. The first experiment took place in the spring under both isolated and free-flying conditions to assess the quality of honey caused by artificial feeding. Sealed honey was collected and analyzed to determine the percentage of sucrose, glucose, fructose and HMF. Also, the pollen density in honey samples was evaluated as another detector for honey quality. The second experiment was conducted during the winter and nectar scarcity to evaluate the effects of the two supplemental sugar feedings on the overwintering performance of honey bee colonies. We measured the sealed brood and the bee bread areas to indicate the colony's growth and development. The results showed that colonies fed sucrose solutions produced honey that fulfilled standard specifications regardless of whether they were placed under an insulator or free-flying colonies, with sugar percentages and HMF levels that comply with standard specifications and no significant difference in sugar content with honey collected from colonies provided with invert sugar. In contrast, colonies provided with invert sugar had higher HMF values in the produced honey when it was the only sugar source under isolation. However, when the colonies were fed invert sugar during the winter, they became more active in collecting pollen, which increased brood rearing and made them more ready for the beginning of the active season. Because it increases pollen-collecting activity, Invert sugar can be considered as a suitable sugar supplement to honey. It may be more successful than sucrose during periods of overwintering and nectar scarcity, resulting in more brood being raised and better preparation is made before the active season. However, care should be taken because overuse at times when natural nectar sources are available could increase the HMF level in the produced honey, causing low-quality honey production.