Yield response, water productivity, and seasonal water production functions for maize under deficit irrigation water management in southern Taiwan

Figures & data

Figure 1. Daily variation in solar radiation, maximum air temperature (T_max), minimum air temperature (T_min), and rainfall during the (a) 2014/2015 and (b) 2015/2016 growing season.

Table 1. Description of the experimental treatments for both seasons.

Treatment	Description
I1	Irrigation was done to replenish soil water content to between 90 and 100% FC. Plots received 60 mm of water at each irrigation event.
I2	Plots received 50 mm of water (83% I1) at each irrigation event.
I3	Plots received 40 mm of water (67% I1) at each irrigation event.
I4	Plots received 30 mm of water (50% I1) at each irrigation event.
I5	Plots received 20 mm of water (33% I1) at each irrigation event.

Figure 2. Seasonal variation in SWC for the different irrigation treatments prior to irrigation application for (a) the 2014/2015 and (b) the 2015/2016 cropping season.

Table 2. Effect of irrigation on some morphological traits of maize.

Parameters	Irrigation treatment
	I1	I2	I3	I4	I5
Plant height (cm)
2014/2015	152.68^ns	152.72	151.49	151.19	151.57
2015/2016	175.10 a	170.57 a	174.88 a	166.05 b	168.83 a
Mean	163.89	161.64	163.185	159.85	160.20
Maximum LAI
2014/2015	5.83 a	5.47 a	4.87 b	4.52 bc	3.98 c
2015/2016	6.05 a	5.51 b	5.01 c	4.61 d	4.39 d
Mean	5.94	5.49	4.94	4.57	4.19
Ear length (cm)
2014/2015	17.83 a	16.20 b	16.53 b	15.05 c	14.75 c
2015/2016	18.70 a	18.57 a	15.73 b	15.33 b	14.93 b
Mean	18.27	17.38	16.13	15.19	14.83
Ear diameter (cm)
2014/2015	4.60 a	4.11 b	4.17 b	3.93 bc	3.75 c
2015/2016	4.76 a	4.34 b	4.18 bc	4.06 bc	3.91 c
Mean	4.68	4.23	4.18	4.00	3.83

Notes: Values followed by the same letter within a row for a given season are not significantly different (p < .05).

^ns Not significant.

Table 3. Effect of irrigation on yield and yield components in the different treatments for both seasons.

Parameters	Irrigation treatment
	I1	I2	I3	I4	I5
Yield (g m^−2)
2014/2015	911.26 a	832.59 a	815.27 a	682.74 b	567.13 c
2015/2016	1105.55 a	1053.75 a	1041.34 ab	849.20 b	792.46 c
Mean	1008.41	943.17	928.31	765.97	679.80
Grain number per ear
2014/2015	477.67 a	448.67 ab	419.02 bc	390.33 c	344.03 d
2015/2016	506.67 a	460.00 ab	429.67 bc	395.00 cd	366.67 d
Mean	492.17	454.34	424.35	392.83	355.35
1000 grain weight (g)
2014/2015	256.17 a	208.57 b	193.93 b	171.24 c	165.06 c
2015/2016	286.06 a	242.57 b	220.27 c	201.23 d	191.97 d
Mean	271.12	225.57	207.10	186.24	178.52
Ear number per plant
2014/2015	1.63^ns	1.59	1.59	1.56	1.41
2015/2016	1.70^ns	1.59	1.67	1.59	1.52
Mean	1.67	1.59	1.63	1.57	1.46
Number of grain per row
2014/2015	33.89 a	32.16 ab	31.33 ab	28.72 bc	26.39 c
2015/2016	35.56 a	33.00 ab	31.67 bc	29.06 cd	27.50 d
Mean	34.73	32.58	31.50	28.89	26.95
Number of row per ear
2014/2015	14.00^ns	13.83	13.67	13.44	13.00
2015/2016	14.23^ns	14.00	13.63	13.57	13.33
Mean	14.12	13.92	13.65	13.51	13.17

Notes: Values followed by the same letter within a row for a given season are not significantly different (p < .05).

^ns Not significant.

Table 4. Correlations between yield, yield components, and total water applied (irrigation + rain) for the two growing seasons.

	Yield	Grain number per ear	1000 grain weight	Ear number per plant	Number of grain per row	Number of row per ear	Total water applied
Yield	1
Grain number per ear	.906**	1
1000 grain weight	.869**	.816**	1
Ear number per plant	.382*	.506**	.441*	1
Number of grain per row	.703**	.904**	.751**	.413*	1
Number of row per ear	.319^ns	.512**	.373*	.402*	.103^ns	1
Total water applied	.868**	.885**	.907**	.473**	.817**	.423*	1

^** Significant at the .01 probability level.

^* Significant at the .05 probability level.

^ns not significant.

Table 5. Total WUE, irrigation water use efficiency (IWUE) and water savings for the different irrigation treatments.

Treatment	WUE (kg m^−3)			IWUE (kg m^−3)			Irrigation water savings (%)
	2014/2015	2015/2016	Mean	2014/2015	2015/2016	Mean
I1	1.52 a	1.94 a	1.72	1.64 a	2.95 a	2.30
I2	1.58 ab	2.04 a	1.81	1.75 a	3.24 b	2.50	14.0
I3	1.79 b	2.24 b	2.02	2.06 b	3.79 c	2.93	28.0
I4	1.78 b	2.01 a	1.90	2.17 bc	3.77 c	2.97	41.9
I5	1.71 b	2.25 b	1.98	2.41 c	4.53 d	3.47	55.9
Mean			1.89			2.83

Note: Values followed by the same letter in a column are not significantly different (p < .05).

Figure 3. Relationships between (a) yield and total water applied (irrigation + rainfall) and (b) yield and seasonal evapotranspiration (ET_c) for the different irrigation treatments during the 2014/2015 (filled circles) and 2015/2016 (open circles) season.

Figure 4. The relationship between seasonal yield depression and seasonal water deficit for maize for the two cropping seasons.