The unpredictable precipitation and water deficit conditions in semiarid regions significantly reduce the yield of summer maize. The exogenous application of plant growth regulators can be used as a strategy to enhance plant stress tolerance and improve the growth and yield of maize under semiarid conditions. Here, we studied the protective role of melatonin application on maize yield using grain filling rate and hormonal crosstalk in maize grains. In the first field experiment, seeds were soaked with melatonin at a concentration of 0 (SM0 ), 25 (SM1 ), 50 (SM2 ), and 75 μM (SM3 ) μM. In contrast, in the second experiment, melatonin was applied on the foliage at the ninth leaf stage at a concentration of 0 (FM0 ), 25 (FM1 ), 50 (FM2 ), and 75 (FM3 ) μM. Our findings showed that melatonin treatments as seed soaking significantly increased single seed weight, seed filling rate in superior, medium and inferior seeds by regulating the hormone levels compared to foliar application. Application of melatonin significantly increased the zeatin + zeatin riboside (Z + ZR), indole-3-acetic acid (IAA), gibberellic acid (GA) contents. However, it significantly inhibited the contents of abscisic acid (ABA) during the seed filling period. The content of Z + ZR, IAA, and GA was positively correlated with the maximum seed filling rate, seed weight, and mean filling rate in middle, superior and lower seeds, while the ABA was negatively correlated. The ABA content in inferior seeds was positively correlated with the maximum and mean seed filling rate. In semiarid regions, melatonin treatment of SM2 and FM2 significantly increased the dry matter per plant, hundred grain weight, seed filling rate, IAA, Z + ZR, GA contents, ear characteristics, and maize yield.

中文翻译：

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褪黑激素提高夏玉米籽粒灌浆率及内源激素机制

半干旱地区不可预测的降水和缺水状况显着降低了夏玉米的产量。植物生长调节剂的外源应用可作为增强植物抗逆性和改善半干旱条件下玉米生长和产量的策略。在这里，我们利用玉米籽粒中的籽粒灌浆率和激素串扰研究了应用褪黑激素对玉米产量的保护作用。在第一个田间试验中，种子用浓度为 0 (SM0)、25 (SM1)、50 (SM2) 和 75 μM (SM3) μM 的褪黑激素浸泡。相比之下，在第二个实验中，褪黑激素以 0 (FM0 )、25 (FM1)、50 (FM2) 和 75 (FM3) μM 的浓度应用于第九叶期的叶子上。我们的研究结果表明，与叶面喷施相比，褪黑激素处理作为浸种处理，通过调节激素水平，显着增加了单粒重、优、中、劣种子的种子灌浆率。应用褪黑激素显着​​增加玉米素+玉米素核苷（Z+ZR）、吲哚-3-乙酸（IAA）、赤霉酸（GA）的含量。然而，它在种子灌浆期显着抑制脱落酸（ABA）的含量。Z+ZR、IAA、GA的含量与中、上、下种子的最大灌浆率、种子重和平均灌浆率呈正相关，而ABA呈负相关。劣质种子中ABA含量与最大灌浆率和平均灌浆率呈正相关。在半干旱地区，