Document Type : Original research papers
Authors
Agricultural botany Department, Faculty of Agriculture, Damietta University, Egypt
Abstract
Two preliminary trials were conducted. The first aimed to identify the seawater salinity level beyond which germination percentage and performance drop below 50% of the control values, considering it is the maximum tolerable salinity for jojoba plants; this was 14,000 ppm. The second trial evaluated three aloe leaf extract (ALE) concentrations (5%, 7.5%, and 10%), revealing that 10% had the greatest effect on seed germination and seedling vigor when compared to the control. As a result, two main experiments were done during the 2021/22 and 2022/23 seasons to assess the effects of 14,000 ppm salinity and 10% ALE, both alone and in combination, on the growth and physiological performance of jojoba plants. The results reveal that irrigation jojoba plants with seawater at a salinity of 14,000 ppm caused significant reductions in the root system size, stem length, number of leaves and branches, total leaf area, fresh and dry weights of roots, stems, and leaves, root/shoot ratio, photosynthetic pigments, total carbohydrates, crude protein, and concentrations of NPK, Ca, and Mg. However, leaf area ratio (LAR) and proline, polyphenols, and Na concentrations increased compared to control plants. Foliar application of 10% ALE on salt-unstressed jojoba plants (irrigated with tap water) significantly enhanced various growth parameters and concentrations of bioconstituents and minerals while decreasing LAR and Na concentration. Furthermore, spraying 10% ALE on salt-stressed jojoba plants (irrigated with 14,000 ppm seawater) not only mitigated the detrimental effects of salinity but also led to remarkable improvements in growth parameters and concentrations of photosynthetic pigments, total carbohydrates, polyphenols, proline, protein, and mineral nutrients, while significantly reducing Na level compared to the control in both seasons. This study recommends applying 10% ALE to improve the growth and physiological performance of jojoba plants, whether under normal or stressful conditions.
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