Foliar Application of Nano-Silicon Improves the Physiological and Biochemical Characteristics of ‘Kalamata’ Olive Subjected to Deficit Irrigation in a Semi-Arid Climate

Abstract

In Egypt’s arid and semi-arid lands where the main olive production zone is located, evapotranspiration is higher than rainfall during winter. Limited research has used nanomaterials, especially nano-silicon (nSi) to improve the growth, development, and productivity of drought-stressed fruit trees, amid the global water scarcity problem. To assess the role of nSi on drought-sensitive ‘Kalamata’ olive tree growth, and biochemical and physiological changes under drought conditions, a split-plot experiment was conducted in a randomized complete block design. The trees were foliar sprayed with nSi in the field using nine treatments (three replicates each) of 0, 150, and 200 mg.L−1 under different irrigation regimes (100, 90, and 80% irrigation water requirements ‘IWR’) during the 2020 and 2021 seasons. Drought negatively affected the trees, but both concentrations of nSi alleviated drought effects at reduced irrigation levels, compared to the non-stressed trees. Foliar spray of both concentrations of nSi at a moderate level (90% IWR) of drought resulted in improved yield and fruit weight and reduced fruit drop percentage, compared to 80% IWR. In addition, there were reduced levels of osmoprotectants such as proline, soluble sugars, and abscisic acid (ABA) with less membrane damage expressed as reduced levels of malondialdehyde (MDA), H2O2 and electrolyte leakage at 90% compared to 80% IWR. These results suggest that ‘Kalamata’ olive trees were severely stressed at 80% compared to 90% IWR, which was not surprising as it is classified as drought sensitive. Overall, the application of 200 mg.L−1 nSi was beneficial for the improvement of the mechanical resistance, growth, and productivity of moderately-stressed (90% IWR) ‘Kalamata’ olive trees under the Egyptian semi-arid conditions.

Application of Silica Nanoparticles in Combination with Two Bacterial Strains Improves the Growth, Antioxidant Capacity and Production of Barley Irrigated with Saline Water in Salt-Affected Soil

“…The combined application of PGPR and SiNPs effectively enhanced the yield, yield-related traits, and NPK uptake by barley grains [ 55 ]. The application of PGPR + SiNPs has the potential to decrease osmotic stress, restrain Na + absorption, and increase K + absorption, resulting in an enhancement of photosynthesis [ 56 ]. All of the above-mentioned benefits were further improved by the combined application of PGPR and SiNPs, which exhibited higher seed fertility with lower sterility combined with heavy seed, which caused high yield and nutrient uptake (N, P, and K), under saline irrigation water in salt-affected soil.…”

Improvement of Nutrient Content, Physiological Traits and Grain Yield of Maize Varieties Grown in Saline Soil by Combining Biochar, Mycorrhizal Fungi and Silicon Foliar Application

“…At the time of planting for AMF treatment, 5 grams of soil containing AMF was used for each plant [6]. Foliar spraying of silicon with a concentration of 200 mg/liter [21][22][23][24][25][26][27][28][29] was carried out in three stages of plant growth, including three to four leaf stage, the beginning of owering and ear formation. Foliar spraying was done using a manual sprayer with a pressure of 20 kPa.…”