Exogenous abscisic acid (ABA) improves the filling process of maize grains at different ear positions by promoting starch accumulation and regulating hormone levels under high planting density

Table 4 Correlation coefficients of endogenous hormone contents with grain filling parameters

Year	Hormone contents	W_max	G_max	G_ave	P
2021	ZR	0.757^*	0.759^*	0.757^*	-0.176
	IAA	0.728^*	0.761^*	0.755^*	-0.376
	ABA	0.783^*	0.778^*	0.779^*	-0.141
	GA₃	-0.801^*	-0.792^*	-0.791^*	0.123
2022	ZR	0.802^*	0.832^*	0.839^**	-0.679
	IAA	0.733^*	0.755^*	0.745^*	-0.573
	ABA	0.771^*	0.789^*	0.800^*	-0.547
	GA₃	-0.818^*	-0.831^*	-0.840^**	0.562

ZR, zeatin riboside; IAA, indole-3-acetic acid; ABA, abscisic acid; GA₃, gibberellin; W_max, grain weight of reaching maximum grain filling rate; G_max, maximum grain filling rate; G_ave, average grain filling rate; P, active grain filling duration. ^* and ^** denote significant level of 0.05 and 0.01 (n = 8), respectively

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