Optimal ethephon application strategies for enhancing lodging resistance and yield in maize under different irrigation and fertilisation regimes

1. High dose ethephon compensates for the efficacy loss of conventional dose ethephon caused by drip fertigation in maize by prolonging the effect duration. 2. High dose ethephon compensates for drip fertigation-induced decline in basal internode quality in maize by modulating hormonal balance and ethylene evolution, thereby enhancing lodging resistance. 3. The optimal ethephon concentration is 270 mg L −1 under traditional water–fertiliser (TWF) with only pre-sowing irrigation, TWF with supplemental drip irrigations, and drip irrigation with water–fertiliser integration (DIWF) without plastic - film mulching, whereas under DIWF with plastic - film mulching, the optimal concentration increases to 540 mg L −1 . Ethephon is widely applied in maize production to reduce centre of gravity and enhance lodging resistance; however, its efficacy is strongly influenced by site-specific irrigation and fertilisation regimes. In this study, we aimed to investigate the effects of optimised ethephon concentrations on lodging resistance and yield under two contrasting management systems—traditional water–fertiliser (TWF) and drip irrigation with water–fertiliser integration (DIWF)—across two ecological regions (Wuqiao [WQ] and Baicheng [BC]). Field experiments were conducted in 2023 and 2024 at WQ and in 2024 at BC, using two maize hybrids (Woyu 3 [WY3] and Jingnongke 728 [JNK728]) and three ethephon concentrations (0 mg L −1 [CK], 270 mg L −1 [E270], and 540 mg L −1 [E540]). DIWF_E270 (DIWF with 270 mg L −1 ethephon) shortened the effect duration by 1.9 d at both ecological sites, leading to increased ear height, reduced stalk quality, and significantly higher lodging rates compared with those in TWF_E270. However, DIWF_E540 exhibited a compensatory effect—prolonging the effect duration by 3.6 d in WQ and 4.9 d in BC compared with that in DIWF_E270. The prolonged effective duration of ethephon optimised basal internode morphology (decreased length, increased cross-sectional area, and greater mass density) and quality (increased rind penetration strength, breaking strength, and lignin deposition) by increasing ethylene evolution while suppressing gibberellin and auxin concentrations. These changes improved plant architecture traits (lower plant height, ear height, centre of gravity height, and ear ratio) and significantly reduced lodging rate. However, its effects on yield varied by site and regime. Optimizing ethephon application strategies achieved the highest productivity. Under TWF with only pre-sowing irrigation, the optimal ethephon concentration was 270 mg L −1 , though it resulted in yield reduction. For TWF with supplemental drip irrigations and DIWF without plastic - film mulching, the optimal concentration remained 270 mg L −1 , increasing yields by 3.9 and by 4.3%, respectively. In contrast, under DIWF with plastic - film mulching, the optimal ethephon concentration was 540 mg L −1 , achieving a 6.5% yield increase. These findings suggest that adjusting ethephon concentrations to irrigation–fertilisation regimes optimise the balance between increased yield and lodging resistance, highlighting the potential of integrating chemical regulation strategies with local agronomic practices for sustainable maize production.