Integrated fertilization with brazide-mediated regulation improves stem mechanical strength, yield, and water-use efficiency of blueberry under semi-arid conditions.

Water scarcity and the potential for soil degradation and environmental problems due to excessive fertilizer use are major challenges to achieving green, sustainable blueberry production with high water-use efficiency. Plant growth regulators (PGRs) play a crucial role in improving blueberry production. This study investigated the effects of CFB1: chemical fertilizer with 1 µmol l-1 brazide; CFB2: chemical fertilizer with 3 µmol l-1 brazide; CFB3: chemical fertilizer with 5 µmol l-1 brazide; OFB1: organic fertilizer with 1 µmol l-1 brazide; OFB2: organic fertilizer with 3 µmol l-1 brazide; OFB3: organic fertilizer with 5 µmol l-1 brazide; BFB1: biofertilizer with 1 µmol l-1 brazide; BFB2: biofertilizer with 3 µmol l-1 brazide; BFB3: biofertilizer with 5 µmol l-1 brazide; CK: no fertilizer with water foliar spray on blueberry resistance to water and lodging stress, N uptake and remobilization, root growth, resource use efficiencies, and economic benefits during the 2022 and 2023 study periods. Our results showed that under the OFB2 treatment, the blueberry stalk lodging index and lodging rate decreased by 25.8% and 31.5%, respectively, through changes in the morphological structure and enhanced soil respiration and water use efficiency (WUE), which increased blueberry yield and substantially reduced crop evapotranspiration (ETc) and greenhouse gas emissions. Under organic fertilizer combined with 3 µmol l-1 brazide application, leaf area index (LAI), Pn, root growth, and bleeding sap were observed to have improved at various growth stages of blueberry. Further, maximum water use efficiency (58.2%, WUE), nitrogen use efficiency (39.2%, NUE), nitrogen recovery efficiency (34.8%, NRE), and nitrogen partial productivity (64.8%, NPP) were obtained under the OFB2 treatment, compared with the CK treatment. In addition, the OFB2 treatment increased N uptake and the percentage of total N content, finally improving the number of flower buds (30.8%), number of new shoots (49.0%), blueberry yield (68.9%), and net profit, respectively. Overall, 3 µmol l-1 brazide with organic fertilizer exhibited the highest blueberry production, antioxidant defense system, NUE, and economic benefits, maintaining high WUE, and could be a promising approach to the sustainable development of blueberry production performance under semi-arid field conditions.