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 2 Effects of ABA application on grain filling properties in 2021 and 2022

Year	Hybrid	Treatment	W_max (g 100 grains^− 1)	G_max (g 100 grains^− 1 d^− 1)	G_ave (g 100 grains^− 1 d^− 1)	P (d)
2021	DH605	ICK	11.89 ± 0.41 d	0.92 ± 0.06 d	0.55 ± 0.02 d	38.83 ± 2.57 a
		IABA	15.16 ± 0.60 c	1.12 ± 0.07 c	0.68 ± 0.06 c	41.26 ± 3.68 a
		SCK	17.89 ± 0.40 b	1.35 ± 0.03 b	0.81 ± 0.02 b	39.62 ± 6.00 a
		SABA	18.81 ± 0.44 a	1.45 ± 0.04 a	0.87 ± 0.03 a	39.02 ± 7.90 a
	ZD958	ICK	12.07 ± 0.26 d	0.87 ± 0.04 d	0.52 ± 0.03 d	41.40 ± 4.21 a
		IABA	13.73 ± 0.41 c	1.04 ± 0.05 c	0.63 ± 0.02 c	39.20 ± 6.82 a
		SCK	16.85 ± 0.30 b	1.24 ± 0.04 b	0.75 ± 0.01 b	40.68 ± 5.05 a
		SABA	17.48 ± 0.25 a	1.32 ± 0.03 a	0.79 ± 0.02 a	39.61 ± 8.01 a
2022	DH605	ICK	11.89 ± 0.35 d	0.90 ± 0.04 d	0.54 ± 0.03 d	39.70 ± 3.46 a
		IABA	15.19 ± 0.47 c	1.13 ± 0.06 c	0.68 ± 0.03 c	40.19 ± 4.25 a
		SCK	17.00 ± 0.52 b	1.25 ± 0.07 b	0.75 ± 0.03 b	40.72 ± 6.20 a
		SABA	18.79 ± 0.48 a	1.45 ± 0.06 a	0.87 ± 0.04 a	38.79 ± 8.21 a
	ZD958	ICK	12.16 ± 0.36 d	0.88 ± 0.06 d	0.53 ± 0.05 d	41.47 ± 5.32 a
		IABA	13.77 ± 0.72 c	1.04 ± 0.08 c	0.63 ± 0.03 c	39.61 ± 7.24 a
		SCK	16.90 ± 0.22 b	1.26 ± 0.03 b	0.76 ± 0.02 b	40.11 ± 6.15 a
		SABA	17.57 ± 0.33 a	1.34 ± 0.02 a	0.81 ± 0.02 a	39.19 ± 8.92 a

ICK and IABA mean inferior grain in the control and ABA treatments, respectively. SCK and SABA mean superior grain in the control and ABA treatments, respectively. Data presented as mean ± S.D. (n = 3). Different letters in the same column within hybrid in the same year denote significant differences. 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

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