Foliar Application of Zinc Oxide Nanoparticles Promotes Drought Stress Tolerance in Eggplant (Solanum melongena L.)

Abstract

Water shortage and salinity are major challenges for sustaining global food security. Using nutrients in the nano-scale formulation including zinc oxide nanoparticles (ZnO NP) is a novel fertilization strategy for crops. In this study, two field-based trials were conducted during 2018 and 2019 to examine the influence of three ZnO NP concentrations (0, 50, and 100 ppm) in eggplant grown under full irrigation (100 of crop evapotranspiration; ETc) and drought stress (60% of ETc). Plant growth, yield, water productivity (WP), physiology, biochemistry, and anatomy responses were evaluated. Drought stress significantly decreased membrane stability index (MSI), relative water content (RWC), and photosynthetic efficiency, thus hampered eggplant growth and yield. In contrast, exogenous ZnO NP to water-stressed eggplant resulted in increased RWC and MSI associated with improved stem and leaf anatomical structures and enhanced photosynthetic efficiency. Under drought stress, supplementation of 50 and 100 ppm ZnO NP improved growth characteristics and increased fruit yield by 12.2% and 22.6%, respectively, compared with fully irrigated plants and nonapplied ZnO NP. The highest water productivity (WP) was obtained when eggplant was irrigated with 60% ETc and foliarly treated with 50 or 100 ppm of ZnO NP, which led to 50.8–66.1% increases in WP when compared with nontreated fully irrigated plants. Collectively, these findings demonstrated that foliar spraying ZnO NP gives the utility for alleviating drought stress effects on eggplant cultivated in saline soil.

Foliar Nourishment with Nano-Selenium Dioxide Promotes Physiology, Biochemistry, Antioxidant Defenses, and Salt Tolerance in Phaseolus vulgaris

“…Leafy nourishment with Se-NPs could improve the protective tissue development in Phaseolus vulgaris leaves, thus strengthening their antidehydration capacity. Similar anatomical findings have been obtained previously [3,55,117].…”

“…However, under severe stress, the natural tolerance of plants does not help with stress resistance since the active ingredients of the plant with low-molecular mass and high-molecular mass do not provide sufficient requirements for defense against stress. Therefore, exogenous adjuvants, including beneficial nutrients in nanoparticles and other auxiliary strategies, must be used to raise the efficiency of antioxidant defense in stressed plants to enable them to function effectively under different stresses [7,10,[54][55][56][57][58][59], including salinity [6,[60][61][62].…”

Exogenous Gibberellic Acid or Dilute Bee Honey Boosts Drought Stress Tolerance in Vicia faba by Rebalancing Osmoprotectants, Antioxidants, Nutrients, and Phytohormones

“…Finally, the negative effects of environmental foes may exceed the natural endurance of stressed plants. In this case, the components of a stressed plant's defense system do not meet adequate defense requirements, and therefore external use of auxiliary substances such as nutrients and other beneficial strategies increases the efficiency of antioxidant defenses, and thus plants can perform efficiently under adverse conditions of environmental foes [61][62][63][64][65].…”

Early Sowing Combined with Adequate Potassium and Sulfur Fertilization: Promoting Beta vulgaris (L.) Yield, Yield Quality, and K- and S-Use Efficiency in a Dry Saline Environment

“…These negative impacts may exceed the natural tolerance capacity of stressed plants. In this case, the components of the stressed plant's defense system do not meet the requirements of adequate defense, and therefore the external use of auxiliary substances such as nutrients and other beneficial strategies helps the plants to increase the efficiency of their antioxidant defenses; thus, plants can perform efficiently under adverse conditions of environmental foes [3,4,8,[56][57][58][59].…”