Drought stress is a significant environmental challenge that adversely affects plant health and productivity. Nano-fertilizers, particularly green synthesized nanoparticles, offer a promising and eco-friendly strategy to enhance plant resilience and productivity under stress. Biogenic chlorapatite nanoparticles (CAp NPs) were synthesized using pectin extracted from Ficus elastica leaves racterized by UV–Vis spectroscopy, TEM, and FT-IR, confirming their spherical morphology, average diameter of 18.5 ± 3.7 nm. Cowpea (Vigna unguiculata) was irrigated with CAp NPs at various dosages (0, 50, 100, and 200 mg/L) to mitigate the harmful effects of drought stress (30% water field capacity) on 15-day-old cowpea plants. Under drought stress, cowpea plants showed significant reductions in growth parameters and increases in oxidative stress markers, whereas CAp NP application (50–200 mg/L) notably enhanced growth, reduced oxidative damage, and improved osmoprotectant (soluble sugars, proteins), nonenzymatic (phenolics, flavonoids, ascorbic acid, reduced glutathione) and antioxidant enzyme activities. The results also revealed that CAp NP treatments significantly enhanced soil microarthropod and key soil properties, including pH, moisture, EC, organic matter, available phosphorus, and total nitrogen. Additionally, CAp NPs modulated gene expression of key stress-responsive genes (catalase2 (CAT2), superoxide dismutase1 (SOD1), dehydration-responsive element binding protein (DREB), and magnesium chelatase (CHLH) and influenced oribatid mite diversity, with the highest diversity and abundance observed at the highest CAp NP dose. These findings highlight the potential of CAp NPs as a promising nano-enabled strategy for sustainable agriculture in water-limited environments. They likely function as a multifaceted stress protectants by providing essential nutrients, boosting antioxidant systems, and improving water-use efficiency.
Elsherif et al. (Sat,) studied this question.