Nano-enhanced growth and resilience strategies for Pomegranate cv. Wonderful: Unveiling the impact of zinc and boron nanoparticles on fruit quality and abiotic stress management

Abstract

The pomegranate fruit is an extremely popular fruit that is grown in various regions around the world. Pomegranate cv. Wonderful confronts severe abiotic stress disorders, like fruit cracking and sunburn, which decrease fruit quality. Nanoparticles offer potential for improving nutrient usage efficiency and lowering undesirable environmental repercussions. During three consecutive stages of development, namely the peak flowering stage, six weeks after peak flowering, and one month prior to harvest, magnificent pomegranate trees were subjected to separate applications of zinc oxide nanoparticles (ZnONPs) and boron oxide nanoparticles (B2O3NPs) at concentrations of 0, 250, 500, and 1000 parts per million (ppm). These treatments were carried out in both the 2021 and 2022 growing seasons. Positive effects were observed at concentrations of 500 and 1000 ppm for ZnONPs and a concentration of 1000 ppm for B2O3NPs on the vegetative growth parameters such as shoot length, leaf area, leaves number per shoot, and canopy volume, besides, leaf chemical characteristics such as leaf chlorophyll concentration and leaf nutrient content such as of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), zinc (Zn), and boron (B). Spraying with 500 and 1000 ppm B2O3NPs reduces the percentage of fruit sunburn, cracking and increased fruiting percentage such as initial fruit set (%), fruit retention (%), total yield of fruits (kg/tree), and increasing yield (%), while fruit drop % was decreased in comparison to other treatments. In both seasons, T4 (22.37, 22.0 %) and T7 (18.74, 19.490 %) showed an increase in initial fruit set (%). Similarly, there was an increase in fruit retention (%) with T4 (33.08, 34.550 %) and T7 (29.13, 29.430 %) compared to the control. The highest yield increasing percentages were observed with T4 (98.88, 100.270 %) and T3 (66.65, 64.980 %) compared to the control. On the other hand, T4 (8.24, 8.04 %) had the lowest fruit cracking, followed by T7 (12.73, 9.9 %) in the 2021 and 2022 seasons. Similarly, the lowest percentage of sunburned fruit was observed with T4 (20.47, 20.4 %) and T4 (18.43, 16.77 %) in the two seasons compared to the control. In general, our findings indicate that the application of ZnONPs and B2O3NPs on fully bloomed wonderful pomegranate trees, six weeks after full bloom, and one month prior to harvest, resulted in enhanced growth and yield. Additionally, this treatment exhibited a reduction in abiotic stress-related issues, such as fruit cracking and sunburn.