Effects of tillage on growth, yield and root lodging of six maize hybrids in upland fields converted from paddy fields in Andosol

Figures & data

Table 1. Meteorological data for 2016 and 2017 during experiments.

	Precipitation (mm)			Daily mean temperature (°C)			Duration of sunshine (h)
Month	2016	2017	Normal value	2016	2017	Normal value	2016^a	2017	Normal value
June	160	123	108	18.0	17.2	17.8	135	179	156
July	131	387	196	21.6	23.6	21.3	144	181	120
August	259	217	182	24.1	21.6	22.9	212	99	138
September	161	194	156	20.3	17.5	18.2	116	167	117
October	185	206	93	11.2	11.4	11.5	177	86	141

Notes: Duration of normal values; 1981–2010 (precipitation, daily mean temperature), 1997–2010 (duration of sunshine). ^aDuration of sunshine in 2016 was obtained from Morioka meteorological observatory of Japan Meteorological Agency because of broken equipment at the NARO Tohoku Agricultural Research Center.

Figure 1. Soil penetration resistance of two tillage methods (a: 2016; b: 2017).

Notes: Bars represent standard error (n = 3).Rotary: Rotary tilling.

Figure 2. Changes in plant height and SPAD value of maize hybrids grown by two tillage methods.

Notes: Bars represent standard error (n = 3). ** and *, significant difference at p < 0.01 and p < 0.05, respectively. ns: not significant (p < 0.05).Rotary: Rotary tilling.

Table 2. Silking day, grain yield and yield components of maize hybrids grown by two tillage methods.

Year	Hybrid (RM)^a	Tillage	Silking day (Days after sowing)	Ear length (cm)	Kernel number (m^−2)	100-grain weight (g)	Grain yileld (g m^−2)
2016	34N84	Rotary	69	16.6	3391	29.9	1015
	(108)	Plowing	68	15.7	2772	27.9	781
	TX1241	Rotary	72	16.9	3429	29.5	1013
	(110)	Plowing	70	16.9	3241	30.9	1003
	kimimaru	Rotary	70	17.1	2984	34.8	1037
	(110)	Plowing	69	17.1	2954	34.7	1027
	P2088	Rotary	72	16.5	3207	32.4	1042
	(118)	Plowing	71	16.7	3060	31.8	998
	SH3786	Rotary	71	17.1	3089	29.5	922
	(118)	Plowing	69	18.2	3318	30.7	1018
	KD641	Rotary	74	17.4	4128	23.7	978
	(114)	Plowing	73	15.7	3704	23.7	895
	Average	Rotary	71	16.9	3371	30.0	1001
		Plowing	70	16.7	3175	30.0	954
	ANOVA	Hybrid (H)	**	ns	*	**	ns
		Tillage (T)	*	ns	ns	ns	ns
		H × T	ns	ns	ns	ns	ns
2017	34N84	Rotary	66	16.2	3450	28.5	978
	(108)	Plowing	66	16.2	3660	26.7	976
	TX1241	Rotary	68	16.3	3713	28.1	1042
	(110)	Plowing	68	16.3	3553	28.0	995
	kimimaru	Rotary	67	16.0	2910	33.2	968
	(110)	Plowing	67	15.5	2621	33.3	873
	P2088	Rotary	68	15.5	3263	31.2	1022
	(118)	Plowing	68	15.4	3519	31.3	1100
	SH3786	Rotary	68	16.0	3373	28.4	959
	(118)	Plowing	69	15.3	3233	28.5	925
	KD641	Rotary	71	15.9	3918	22.9	896
	(114)	Plowing	71	15.6	4157	24.0	1000
	Average	Rotary	68	16.0	3438	28.7	978
		Plowing	68	15.7	3457	28.6	978
	ANOVA	Hybrid (H)	**	ns	**	**	ns
		Tillage (T)	ns	ns	ns	ns	ns
		H × T	ns	ns	ns	ns	ns

Notes: **Significant at the 0.01 probability level. *Significant at the 0.05 probability level. ns, nonsignificant at the 0.05 probability level.

^aRelative maturity. Rotary: Rotary tilling.

Table 3. Traits of root lodging of maize hybrids grown by two tillage methods.

Year	Hybrid (RM)^a	Tillage	HPR^b (N)	Culm length (cm)	Ear height (cm)	HPR-value	Root lodging (10 plants^−1)	Stalk lodging (10 plants^−1)
2016	34N84	Rotary	27.5	248	103	6.2 ± 0.5	-	-
	(108)	Plowing	28.9	250	102	6.1 ± 0.3	-	-
	TX1241	Rotary	22.5	276	120	9.4 ± 1.3	-	-
	(110)	Plowing	31.7	280	125	6.5 ± 0.8	-	-
	kimimaru	Rotary	26.8	268	133	7.3 ± 0.6	-	-
	(110)	Plowing	29.8	272	138	6.9 ± 0.1	-	-
	P2088	Rotary	24.5	289	128	8.3 ± 0.3	-	-
	(118)	Plowing	34.4	297	131	6.3 ± 0.7	-	-
	SH3786	Rotary	18.3	300	135	11.5 ± 0.6	-	-
	(118)	Plowing	32.6	312	135	6.5 ± 0.1	-	-
	KD641	Rotary	32.4	270	117	5.8 ± 0.2	-	-
	(114)	Plowing	34.2	265	116	5.9 ± 0.8	-	-
	Average	Rotary	25.3	275	122	8.1 ± 0.5	-	-
		Plowing	31.9	279	124	6.4 ± 0.2	-	-
	ANOVA	Hybrid (H)	**	**	**	-	-	-
		Tillage (T)	✝	ns	*	-	-	-
		H × T	*	ns	ns	-	-	-
2017	34N84	Rotary	24.0	257	126	8.6 ± 0.4	8.3	0.7
	(108)	Plowing	24.7	256	128	8.0 ± 0.1	6.3	0.3
	TX1241	Rotary	25.4	298	144	8.8 ± 1.2	4.3	1.0
	(110)	Plowing	27.3	289	138	7.8 ± 0.3	3.3	2.0
	kimimaru	Rotary	19.4	269	133	11.5 ± 1.3	8.0	2.0
	(110)	Plowing	22.1	270	131	9.4 ± 0.4	6.0	2.7
	P2088	Rotary	25.0	302	142	9.7 ± 0.9	8.7	1.0
	(118)	Plowing	30.5	294	140	7.6 ± 0.9	2.0	2.0
	SH3786	Rotary	18.3	321	151	13.2 ± 1.0	9.0	0.7
	(118)	Plowing	18.9	319	151	13.7 ± 1.2	8.7	1.0
	KD641	Rotary	28.5	294	144	7.9 ± 0.8	7.0	0.7
	(114)	Plowing	35.2	290	141	6.7 ± 0.4	0.3	4.3
	Average	Rotary	23.4	290	140	10.0 ± 0.6	7.6	1.0
		Plowing	26.5	286	138	8.9 ± 0.6	4.4	2.1
	ANOVA	Hybrid (H)	**	**	**	-	*	ns
		Tillage (T)	✝	ns	ns	-	*	*
		H × T	ns	ns	ns	-	*	ns

Notes: **Significant at the 0.01 probability level. *Significant at the 0.05 probability level. ✝Significant at the 0.1 probability level. ns, nonsignificant at the 0.1 probability level.

^aRelative maturity, ^bhorizontal pulling resistance. HPR-value indicated data ± standard error. Rotary: Rotary tilling.

Figure 3. Relationships between number of root lodged plants and HPR (a) or HPR-value (b) in 2017.

Notes: ** significant difference at p < 0.01. Rotary: Rotary tilling; HPR: horizontal pulling resistance.