Effect of irrigation and mulch levels on growth and yield components, yield, and water use efficiency of hot pepper (capsicum annuum L) in Eastern Ethiopia

Figures & data

Figure 1. Geographical location of the study area.

Table 1. Treatment’s combinations of the experiment.

Treatments	Explanations
T1 = DI1M1	100%ETc + no mulch
T2 = DI1M2	100%ETc + 3 t/hastraw mulch
T3 = DI1M3	100%ETc + 6 t/ha straw mulch
T4 = DI1M4	100%ETc + 9 t/ha straw mulch
T5 = DI2M1	75%ETc + no mulch
T6 =DI2M2	75%ETc +3 t/ha straw mulch
T7 = DI2M3	75%ETc + 6 t/ha straw mulch
T8 = DI2M4	75%ETc + 9 t/ha straw mulch
T9 =DI3M1	50%ETc + no mulch
T10 = DI3M2	50%ETc + 3 t/ha straw mulch
T11 =DI3M3	50%ETc + 6 t/ha straw mulch
T12 =DI3M4	50%ETc + 9 t/ha straw mulch

T: treatment; ETc: Crop evapotranspiration; DI: deficit irrigation; M: mulch.

Table 2. Selected physical properties of the experimental soil.

Sampling depth (cm)	Particle size distribution (%)			Textural class	BD (g cm^-3)	FC [(%)w/w]	PWP [(%)w/w]	TAW (mm/m)
	Sand	Silt	Clay
0–20	67	9	24	Sandy clay loam	1.22	32.40	17.50	181.78
20–40	65	6	29	Sandy clay loam	1.29	33.50	18.20	197.37
40–60	63	7	30	Sandy clay loam	1.33	34.30	18.40	211.47
60–80	62	6	32	Sandy clay loam	1.34	38.12	21.10	228.07

BD: Bulk Density; FC: Field Capacity; PWP: Permanent Wilting Point; TAW: Total Available Water.

Table 3. Some chemical properties of the experimental soil and irrigation water.

Soil depth (cm)	Soil chemical properties
	pH	EC (dS/m)	OC (%)	TN (%)	Av. P (mg/kg)
0–20	7.37	0.13	1.08	0.10	16.44
20–40	7.41	0.11	0.99	0.07	14.18
40–60	7.45	0.16	0.74	0.03	11.68
60–80	7.59	0.14	0.59	0.01	7.12
Average	7.46	0.14	0.85	0.05	12.36
Irrigation water chemical properties
			Ca + Mg (meq/l)	Na (mq/l)	SAR
	7.06	0.83	4.07	0.16	0.112

EC: electrical conductivity; OC: organic carbon; TN: total nitrogen; Av. P: available phosphorus.

Table 4. Interaction effects of deficit irrigation by straw mulch levels on days to 50% flowering and days to maturity of hot pepper.

Deficit irrigation levels	Days to 50% flowering				Days to maturity
	Mulch levels (t/ha)				Mulch levels (t/ha)
	0	3	6	9	0	3	6	9
100% ETc	48.33^g	52.67^e	62.33^b	64.33^a	100.33^g	103.67^e	112.33^b	115.33^a
75% ETc	44.33^i	48.33^g	56.00^d	62.00^b	96.33^i	99.33^h	107.00^d	113.00^b
50% ETc	43.00^i	46.33^h	50.67^f	58.33^c	95.00^j	96.33^i	101.67^f	109.33^c
LSD (5%)	1.35				0.93
CV (%)	1.50				0.53

For the respective parameters, means followed by the same letter(s) are not significantly different from each other at 5% level of significance, LSD (0.05) = Least Significance Difference at 5% and CV (%) = coefficient of variation.

Table 5. Interaction effect of deficit irrigation and straw mulch levels on plant height and number of branches per plant of hot pepper.

Deficit irrigation levels	Plant height (cm)				Number of branches per plant
	Mulch levels (t/ha)				Mulch levels (t/ha)
	0	3	6	9	0	3	6	9
100% ETc	53.18^gh	63.46^e	77.70^b	81.30^a	14.2^de	15.20 ^cd	20.80^a	22.00^a
75%ETc	51.24^h	59.60^f	66.24^d	74.02^c	11.80^f	14.6d^e	18.00^b	18.40^b
50%ETc	48.38^i	51.76^h	54.98^g	68.66^d	11.00^f	12.20^f	13.80^e	16.00^c
LSD (5%)	2.74				1.39
CV (%)	2.58				5.25

For the respective parameters, means followed by the same letter(s) are not significantly different from each other at 5% level of significance, LSD (0.05) = Least Significance Difference at 5% and CV (%) = coefficient of variation.

Table 6. Interaction effect of deficit irrigation and straw mulch levels on number of leaves per plant of hot pepper.

Deficit irrigation	Leaf number per plant
	Straw mulch levels (t/ha)
	0	3	6	9
100%ETc	490.68^e	539.50^d	855.84^ab	875.61^a
75%ETc	434.51^fg	508.85^de	835.49^b	851.76^ab
50%ETc	403.28^g	441.67^f	495.75^e	680.23^c
LSD (%)	33.73
CV (%)	13.11

For the respective parameters, means followed by the same letter(s) are not significantly different from each other at 5% level of significance, LSD (0.05) = Least Significance Difference at 5% and CV (%) = coefficient of variation.

Table 7. Interaction effect of deficit irrigation and straw mulch levels on fruit length and number of fruits per plant of hot pepper.

Deficit irrigation levels	Fruit length (cm)				Number of fruits per plant
	Straw mulch levels (t/ha)				Straw mulch levels (t/ha)
	0	3	6	9	0	3	6	9
100% ETc	6.82^ef	8.11 ^cd	9.44^b	10.70^a	56.33^e	59.94^e	79.57^a	69.08^c
75%ETc	5.72^gh	7.42^de	9.42^b	9.94^b	43.58^g	57.90^e	74.94^b	64.52^d
50%ETc	5.06^h	6.12^fg	7.02^e	8.62^c	30.22^i	37.08^h	50.41^f	57.42^e
LSD (5%)	0.73				18.06
CV (%)	5.51				12.37

For the respective parameters, means followed by the same letter(s) are not significantly different from each other at 1% level of significance, LSD (0.01) = Least Significance Difference at 1% and CV (%) = coefficient of variation.

Table 8. Interaction effect of deficit irrigation and straw mulch levels on marketable and unmarketable yield of hot pepper.

Deficit irrigation levels	Marketable yield (t/ha)				Unmarketable yield
	Straw mulch levels (t/ha)				Straw mulch levels (t/ha)
	0	3	6	9	0	3	6	9
100% ETc	8.75^ef	9.31^de	12.36^a	10.73^bc	0.21^f	0.33^d	0.40^b	0.45^a
75% ETc	6.77^gh	8.99^def	11.64^ab	10.02 ^cd	0.17^g	0.30^d	0.41^b	0.37^c
50% ETc	4.66^i	5.76^hi	7.83^fg	8.92^def	0.15^g	0.16^g	0.19^f	0.25^e
(LSD 5%)	1.233				0.03
CV (%)	8.26				5.17

For the respective parameters, means followed by the same letter(s) are not significantly different from each other at 1% level of significance, LSD (0.01) = Least Significance Difference at 1% and CV (%) = coefficient of variation.

Table 9. Interaction effect of deficit irrigation and straw mulch levels on total yield of hot pepper.

Deficit irrigation levels	Total yield (t/ha)
	Straw mulching levels (t/ha)
	0	3	6	9
100% ETc	8.96^ef	9.64^de	12.81^a	11.13^bc
75% ETc	6.94^gh	9.29^de	12.05^ab	10.39 ^cd
50% ETc	4.81^i	5.92^hi	8.02^fg	9.17^def
LSD (5%)	1.24
CV (%)	8.03

For the respective parameters, means followed by the same letter(s) are not significantly different from each other at 1% level of significance, LSD (0.01) = Least Significance Difference at 1% and CV (%) = coefficient of variation.

Table 10. Water use efficiency, irrigation water saved, and relative yield reduction due to imposition of deficit irrigation and application of straw mulch at different levels on hot pepper.

Treatments	Gross irrigation(m^3/ha)	Total yield (kg/ha)	WUE (kg/m^3)	Water saved (m^3)	RYR (%)	Additional area to be cultivated (ha)	Additional yield (t/per additional ha)
DI1M1	4594.3	8960	1.95^f	0	29.21	0.00	0.00
DI1M2	4594.3	9640	2.10^f	0	24.68	0.00	0.00
DI1M3	4594.3	12810	2.79 ^cd	0	0.00	0.00	0.00
DI1M4	4594.3	11130	2.42^de	0	13.19	0.00	0.00
DI2M1	3445.8	6940	2.01^f	1148.5	45.23	0.33	2.31
DI2M2	3445.8	9290	2.70 ^cd	1148.5	27.27	0.33	3.10
DI2M3	3445.8	12050	3.49^b	1148.5	5.83	0.33	4.02
DI2M4	3445.8	10390	3.01^c	1148.5	18.93	0.33	3.46
DI3M1	2297.2	4810	2.09^ef	2297.1	62.30	1.00	4.81
DI3M2	2297.2	5920	2.57^d	2297.1	53.40	1.00	5.92
DI3M3	2297.2	8020	3.49^b	2297.1	36.65	1.00	8.02
DI3M4	2297.2	9170	3.99^a	2297.1	27.83	1.00	9.17
LSD (5%)	0.398
CV (%)	8.64

Means within a column followed by the same letter are not significantly different at 1% level of significance. DI: deficit irrigation; M: mulch; WUE: Water use efficiency; RYR: Relative Yield Reduction.

Table 11. Effect of deficit irrigation and straw mulch levels on yield response factor of hot pepper.

Treatments	Yield (kg/ha)	ETa (mm)	$\frac{\mathit{\text{ETa}}}{\mathit{\text{ETm}}}$	$\frac{\mathit{\text{Ya}}}{\mathit{\text{Ym}}}$	1 - $\frac{\mathit{\text{ETa}}}{\mathit{\text{ETm}}}$	1 - $\frac{\mathit{\text{Ya}}}{\mathit{\text{Ym}}}$	Ky = $\frac{1\hspace{0.17em}-\hspace{0.17em}\frac{\mathit{\text{Ya}}}{\mathit{\text{Ym}}}}{1\hspace{0.17em}-\hspace{0.17em}\frac{\mathit{\text{ETa}}}{\mathit{\text{ETm}}}}$
DI1M1	8960	275.66	1	0.70	0	0.30	–
DI1M2	9640	275.66	1	0.75	0	0.25	–
DI1M3	12810	275.66	1	1.00	0	0.00	–
DI1M4	11130	275.66	1	0.87	0	0.13	–
DI2M1	6940	206.75	0.75	0.54	0.25	0.46	1.83
DI2M2	9290	206.75	0.75	0.73	0.25	0.27	1.10
DI2M3	12050	206.75	0.75	0.94	0.25	0.06	0.24
DI2M4	10390	206.75	0.75	0.81	0.25	0.19	0.76
DI3M1	4810	137.83	0.5	0.38	0.5	0.62	1.25
DI3M2	5920	137.83	0.5	0.46	0.5	0.54	1.08
DI3M3	8020	137.83	0.5	0.63	0.5	0.37	0.75
DI3M4	9170	137.83	0.5	0.72	0.5	0.28	0.57

DI: deficit irrigation; M: mulch; Eta: actual evapotranspiration; ET_m: maximum evapotranspiration; Ya: actual yield; Y_m: maximum yield.

Data availability statement

The data that support the findings of this study are available from the corresponding author, [Addis Hailu], upon reasonable request.