Boron Supplementation and Phytohormone Application: Effects on Development, Fruit Set, and Yield in Macadamia Cultivar 'A4' (Macadamia integrifolia, M. tetraphylla)

文献类型: 外文期刊

第一作者: Zhou, Zhang-Jie

作者: Zhou, Zhang-Jie;Zhao, Zi-Xuan;Zhou, Jing-Jing;Zhang, Jin-Zhi;Yang, Fan;Zhang, Jin-Zhi

作者机构:

关键词: macadamia; boron fertilizer; plant hormones; fruit set; regulatory mechanism

期刊名称:PLANTS-BASEL ( 影响因子:4.1; 五年影响因子:4.5 )

ISSN: 2223-7747

年卷期: 2025 年 14 卷 16 期

页码:

收录情况: SCI

摘要: Macadamia (Macadamia integrifolia), Macadamia tetraphylla and hybrids, a crop of high economic and nutritional importance, faces challenges with low fruit set rates and severe fruit drop. To address this, we investigated the effects of exogenous plant growth regulators (PGRs) and boron fertilizer on the development, fruit set, and yield of the A4 macadamia variety. The study was conducted in 2024 at the Lujiangba research base (China, Yunnan Province). Five treatments were applied during key growth stages: boron (B), brassinosteroids (BR), N-(2-Chloro-4-pyridyl)-N'-phenylurea (CPPU), 6-benzylaminopurine (6-BA), and gibberellic acid (GA3). Growth stages include flower bud formation, peak flowering, and fruiting. Our findings revealed that B treatment significantly increased pollen viability (95.69% improvement) and raceme length (23.97% increase), while BR enhanced flower count per raceme (26.37% increase) and CPPU improved flower retention (10.53% increase). Additionally, GA3 and 6-BA promoted leaf expansion in new shoots, increasing leaf length by 39.83% and 31.39%, respectively. Notably, B application significantly improved total yield (43.11% increase) and fruit number (39.12% increase), whereas BR maximized nut shell diameter (5.7% increase) and individual nut weight (19.9% increase). Furthermore, CPPU and 6-BA markedly improved initial fruit set rates, while GA3, BR, and B effectively reduced early fruit drop. Physiological analyses indicated that elevated soluble sugars and proteins in flowers correlated with higher initial fruit set, whereas increased endogenous cytokinin and GA3 levels improved fruit retention and reduced drop rates. Based on these findings, we propose an integrated approach to optimize productivity: applying 0.02% B at the floral bud stage, 2 mg/L 6-BA at full bloom, and a combination of 0.02% B and 0.2 mL/L BR during early fruit set. This strategy not only enhances yield but also mitigates fruit drop, offering practical solutions for macadamia production.

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