Influences of water management combined with organic mulching on taro plant growth and corm nutrition

Figures & data

Figure 1. Layout of the experimental plots showing the split-plot design with the two treatment factors, water regime (i.e. upland and flooding) and mulching (i.e. control, sugarcane bagasse, peanut hull, and rice husk), assigned in the whole plot and subplot, respectively, for taro cultivation in the two cropping seasons. Season I was the winter cropping from 24 December 2013 to 30 September 2014 and Season II was the spring cropping from 14 March to 31 December 2014. Three sampling zones in a subplot are delineating with the dash lines, in which was one plant randomly selected as the replicates (i.e. Reps. 1, 2, and 3)

Figure 2. Profiles of the monthly temperature (Mon. temp.), relative humidity (RH), daylight hour, and rainfall from Dec. 2013 to Dec. 2014

Table 1. Selected physicochemical properties of the soil (i.e. caly, sand, pH, cation exchangeable capacity (CEC), organic matter (OM), total nitrogen (TN), Bray 1-phosphorous (B1P), and exchangeable potassium (Ex. K), calcium (Ex. Ca) and magnesium (Ex. Mg)) and the compositions of the mulching materials (i.e. ash, OM, N, P, K, Ca, Mg, and ratio of carbon to nitrogen (C/N))

		Physicochemical properties/Compositions
Soil/Mulching materials		Clay	Sand	pH	CEC	OM	TN	B1P	Ex. K	Ex. Ca	Ex. Mg
		%			cmol kg^−1	%	g kg^−1	mg kg^−1
Lithic Udorthent		23	26	5.33	11.49	2.39	1.43	50.57	113.7	698.3	136.0
		Ash	OM		N	P		K	Ca	Mg	C/N
		%			g kg^−1 dry weight
sugarcane bagasse		35.2	64.8		10.3	12.6	3.12		13.5	3.82	29.0
peanut hull		5.48	94.5		12.5	1.68	3.95		4.26	1.89	34.8
rice husk		10.3	89.7		4.8	0.76	4.84		0.42	0.42	86.2

Table 2. Least squares means of the soil properties (i.e. pH, organic matter (OM), total nitrogen (TN), Bray 1-phosphorous (B1P), and exchangeable potassium (Ex. K), calcium (Ex. Ca) and magnesium (Ex. Mg)) for the taro cultivation with different mulching materials under the upland (UPL) and flooding (FLO) regimes in cropping seasons I and II during 2013-2014

		Soil properties
		Season I (2013)							Season II (2014)
Water regimes	Mulches	pH	OM	TN	B1P	Ex. K	Ex.Ca	Ex. Mg	pH	OM	TN	B1P	Ex. K	Ex. Ca	Ex. Mg
			%	g kg^−1	mg kg^−1					%	g kg^−1	mg kg^−1
UPL	control	5.1 cde^†	1.8 d	1.07 c	66.3 d	232 f	773 c	114 c	4.9 d	1.3 e	0.77 d	61.8 c	121 c	664 e	114 c
	sugarcane bagasse	5.5 abc	2.2 cd	1.35 ab	69.5 cd	294 de	908 b	213 b	5.3 c	1.7 c	0.95 c	73.9 ab	192 b	913 a	194 ab
	peanut hull	5.2 bc	2.5 c	1.44 ab	76.2 ab	277 e	872 b	219 b	5.6 ab	1.7 c	1.16 a	72.3 b	223 a	830 bc	207 a
	rice husk	5.6 ab	3.2 ab	1.48 a	76.7 ab	311 d	877 b	217 b	5.6 ab	1.8 bc	0.98 bc	79.4 ab	196 b	792 c	194 ab
FLO	control	4.8 e	2.0 cd	1.21 bc	46.1 e	385 c	802 c	136 c	5.3 c	1.5 d	0.88 cd	81.3 a	102 d	713 de	136 c
	sugarcane bagasse	5.4 abc	2.7 bc	1.48 a	72.2 bc	406 bc	922 b	246 a	5.6 a	1.9 b	1.00 bc	80.7 ab	225 a	723 d	176 b
	peanut hull	5.7 a	3.2 a	1.56 a	79.5 a	431 ab	919 b	213 b	5.4 bc	2.2 a	1.15 a	76.1 ab	214 a	673 de	190 ab
	rice husk	5.4 abc	2.8 abc	1.53 a	76.8 ab	438 a	978 a	225 ab	5.7 a	2.3 a	1.09 abc	75.9 ab	213 a	879 ab	191 ab
SE ^‡		0.13	0.17	0.078	1.50	8.5	16.3	8.1	0.08	0.05	0.040	2.86	3.8	17.6	7.0

† Values of least squares means (i.e. lsmeans) within each column followed by the same letters are not significantly different at the 0.05 level.

‡ Standard errors for the lsmeans obtained by using the GLM procedure in SAS programs.

Table 3. Least squares means of the weed density during 60, 120, 180, and 240 days after transplanting (DAT) for the taro cultivation with different mulching materials under the upland (UPL) and flooding (FLO) regimes in cropping seasons I and II during 2013-2014

		Weed density
		Season I (2013)				Season II (2014)
Water regimes	Mulches	60 DAT	120 DAT	180 DAT	240 DAT	60 DAT	120 DAT	180 DAT	240 DAT
				plant m^−2
UPL	control	29.3 a^†	65.3 a	53.3 a	10.7 a	38.7 a	66.7 a	53.3 a	20.0 a
	sugarcane bagasse	32.0 a	42.7 b	34.7 b	9.3 a	18.7 b	42.7 b	41.3 b	13.3 ab
	peanut hull	18.7 b	38.7 b	34.7 b	10.7 a	13.3 bc	40.0 bc	40.0 b	13.3 ab
	rice husk	10.7 c	40.0 b	29.3 b	8.0 a	8.0 c	36.0 c	37.3 b	10.7 b
FLO	control	9.2 cd	8.0 c	12.0 c	10.7 a	5.3 de	9.3 d	5.3 c	20.0 a
	sugarcane bagasse	6.7 cd	5.3 cd	6.7 cd	8.0 a	0.0 f	1.3 e	4.0 c	10.7 b
	peanut hull	5.2 cd	4.0 cd	4.0 cd	9.3 a	1.3 ef	2.7 e	5.3 c	12.0 ab
	rice husk	2.7 d	1.3 d	1.3 d	10.7 a	0.0 f	1.3 e	1.3 c	8.0 b
SE ^‡		2.48	1.32	2.68	2.24	1.56	1.60	2.48	2.64

† Values of least squares means (i.e. lsmeans) within each column followed by the same letters are not significantly different at the 0.05 level.

‡ Standard errors for the lsmeans obtained by using the GLM procedure in SAS programs.

Table 4. Least squares means of the growth factors (i.e. plant height, leaf length, and leaf width) at 240 days after transplanting, for the taro cultivation with different mulching materials under the upland (UPL) and flooding (FLO) regimes in cropping seasons I and II during 2013-2014

		Growth factors
		Season I (2013)			Season II (2014)
Water regimes	Mulches	plant height	leaf blade length	leaf blade width	plant height	leaf blade length	leaf blade width
		cm
UPL	control	137.2 d^†	44.2 c	33.9 c	134.1 bcd	35.7 b	31.3 a
	sugarcane bagasse	136.6 d	49.2 ab	39.6 a	132.7 d	36.2 b	30.1 a
	peanut hull	145.9 c	49.6 a	40.6 a	133.8 cd	40.4 a	31.5 a
	rice husk	153.4 b	48.9 ab	39.4 a	137.5 ab	37.5 ab	30.0 a
FLO	control	170.1 a	46.9 b	37.1 b	134.8 bcd	37.8 ab	30.4 a
	sugarcane bagasse	173.5 a	48.9 ab	39.8 a	136.7 abc	38.3 ab	30.8 a
	peanut hull	177.2 a	49.4 a	40.3 a	134.1 cd	39.0 ab	30.9 a
	rice husk	176.6 a	49.3 ab	39.3 a	139.6 a	38.1 ab	30.8 a
SE ^‡		2.42	0.80	0.49	1.17	1.32	0.44

† Values of least squares means (i.e. lsmeans) within each column followed by the same letters are not significantly different at the 0.05 level.

‡ Standard errors for the lsmeans obtained by using the GLM procedure in SAS programs.

Figure 3. Photographs of the corms for the taro plants under (a) upland and (b) flooded cultivations, showing the morphological characters (i.e. shape, size and internal color of raw corm). Scale bar = 2 cm

Table 5. Least squares means of the taro corm attributes (i.e. length, major axis, fresh weight, and yield) for the cultivation with different mulching materials under the upland (UPL) and flooding (FLO) regimes in cropping seasons I and II during 2013-2014

		Corm attributes
		Season I (2013)				Season II (2014)
Water regimes	Mulches	length	major axis	fresh weight	yield	length	major axis	fresh weight	yield
		cm		g plant^−1	kg m^−2	cm		g plant^−1	kg m^−2
UPL	control	14.5 e^†	7.57 c	471.7 g	1.71 g	17.6 c	9.03 b	574.0 d	2.08 d
	sugarcane bagasse	15.1 d	8.70 a	521.0 f	1.89 f	18.6 b	9.50 a	612.7 b	2.22 b
	peanut hull	15.7 c	8.70 a	541.7 e	1.96 e	17.5 c	8.80 b	581.5 cd	2.10 cd
	rice husk	15.9 bc	8.80 a	570.0 d	2.06 d	18.1 bc	8.83 b	598.5 bc	2.17 bc
FLO	control	16.3 ab	8.27 b	598.5 c	2.17 c	18.8 b	6.53 d	529.3 e	1.92 e
	sugarcane bagasse	16.3 a	8.33 b	623.3 b	2.26 b	19.8 a	7.20 c	638.0 a	2.31 a
	peanut hull	16.2 ab	8.17 b	616.5 b	2.23 b	18.4 b	6.57 d	535.5 e	1.94 e
	rice husk	16.5 a	8.37 b	643.3 a	2.33 a	19.7 a	6.90 cd	583.3 cd	2.11 cd
SE ^‡		0.15	0.082	2.81	0.010	0.26	0.129	6.65	0.024

† Values of least squares means (i.e. lsmeans) within each column followed by the same letters are not significantly different at the 0.05 level.

‡ Standard errors for the lsmeans obtained by using the GLM procedure in SAS programs.

Table 6. Least squares means of the proximate compositions (i.e. moisture (Moist.), starch (Star.), crude protein (CP), crude lipid (CL), crude fiber (CF), soluble sugar (SS), ash, and energy value (EV)) of taro corm from the cultivation with different mulching materials under the upland (UPL) and flooding (FLO) regimes in cropping seasons I and II during 2013-2014

		Proximate compositions
		Season I (2013)								Season II (2014)
Water regimes	Mulches	Moist.	Star.	CP	CL	CF	SS	Ash	EV	Moist.	Star.	CP	CL	CF	SS	Ash	EV
		g (100 g fw)^−1							kcal (100 g fw)^−1	g (100 g fw)^−1							kcal (100 g fw)^−1
UPL	control	64.5 bc^†	25.8 bc	1.11 b	0.28 b	0.67 cd	10.3 ab	0.24 c	151 bc	63.9 bc	26.6 b	1.14 b	0.19 ab	0.69 b	9.9 b	1.07 ab	152 b
	sugarcane bagasse	65.7 abc	25.4 bc	1.08 b	0.32 b	0.66 d	9.1 bc	0.63 a	145 cd	64.7 bc	26.0 bc	1.13 bc	0.18 abc	0.68 b	9.7 bc	0.75 c	149 b
	peanut hull	67.7 ab	23.5 d	1.08 b	0.42 a	0.63 f	7.8 cd	0.53 ab	133 e	69.0 a	23.4 d	0.97 d	0.15 c	0.60 e	7.7 de	0.15 e	130 d
	rice husk	64.1 bc	26.1 b	1.13 ab	0.36 ab	0.70 b	10.5 ab	0.17 c	154 b	61.4 c	28.7 a	1.22 a	0.20 a	0.75 a	11.5 a	1.23 a	167 a
FLO	control	62.7 c	27.5 a	1.18 a	0.34 ab	0.72 a	11.5 a	0.18 c	164 a	65.9 ab	25.2 c	1.11 bc	0.16 bc	0.66 cd	8.9 bcd	0.81 bc	142 c
	sugarcane bagasse	64.9 bc	25.9 bc	1.11 b	0.35 ab	0.68 c	9.1 bc	0.36 bc	148 bcd	65.0 bc	26.9 b	1.10 bc	0.18 abc	0.67 bc	9.9 b	0.46 d	153 b
	peanut hull	66.4 abc	25.1 c	1.08 b	0.36 ab	0.65 e	8.7 bcd	0.19 c	143 d	69.2 a	22.8 d	0.98 d	0.18 abc	0.60 e	6.7 e	1.07 ab	123 e
	rice husk	69.9 a	21.8 e	0.97 c	0.30 b	0.59 g	6.9 d	0.30 c	121 f	67.0 ab	25.1 c	1.07 c	0.17 abc	0.64 d	8.6 cd	0.38 de	141 c
SE ^‡		1.55	0.29	0.183	0.029	0.003	0.64	0.074	2.7	1.21	0.31	0.020	0.010	0.007	0.39	0.090	1.8

† Values of least squares means (i.e. lsmeans) within each column followed by the same letters are not significantly different at the 0.05 level.

‡ Standard errors for the lsmeans obtained by using the GLM procedure in SAS programs.