Cowpea (Vigna unguiculata L. Walp) morpho-physiological and yield responses to chemical, organic, and biofertilizers at various watering levels utilizing drip irrigation system

Figures & data

Table 1. Physical and chemical characteristics of the study soil during the growing seasons (2021 and 2022).

Particulars	Soil depth (cm)
	0–15	15–30
Mechanical characteristics
Sand (%)	90.91	88.60
Silt (%)	12.22	11.10
Clay (%)	0.7	0.71
Physical characteristics
Moisture (%)	18.00	19.55
Bulk density (g cm^−3)	1.45	1.40
Chemical characteristics
pH	7.82	7.71
EC (dS m^−1)	0.23	0.11
Organic carbon (%)	0.60	0.55
Available N (mg kg^−1)	0.55	0.70
Available P (mg kg^−1)	7.45	6.00
Available K (mg kg^−1)	8.28	7.02

Table 2. Chemical composition of vegetative potato tops.

Water content (%)	Ash (%)	Organic matter (%)	Organic carbon (%)	Total N (%)	Total P (%)	Total K (%)	C/N ratio
18.85	10.20	73.51	32.90	0.65	0.88	2.00	50.61

Table 3. Chemical analysis of irrigation water.

pH	EC (dS m^−1)	Soluble anions (mmol l^−1)				Soluble cations (mmol l^−1)
		CO3^2-	HCO3^−	Cl^−	SO4^2-	Ca^2+	Mg^2+	Na^+	K^+
6.72	4.48	0.001	8.02	21.43	4.63	0.28	8.53	13.24	0.26

Table 4. Two-way ANOVA analysis of the studied variables.

Variables	Irrigation level	Fertilizer type	Irrigation x Fertilizer
Plant height (cm plant ^−1)	23.89***	58.68***	0.97 ns
Dry biomass (kg ha^−1)	19.62***	1036.12***	0.88 ns
No of pods (Pod plant^−1)	64.09***	163.54***	12.58***
No of seeds (Seed pod^−1)	119.16***	300.45***	2.90**
Weight of 100 seeds (g 100 seed^−1)	21.16***	107.62***	0.80 ns
Seed yield (kg ha^−1)	4310.36***	7922.28***	384.54***
Total soluble sugars (%)	235.41***	86.81***	5.48***
Total protein (%)	514.12***	439.10***	13.57***
Proline (mg g^−1)	449.98***	162.04***	5.21***
Ash (%)	10.60***	12.46***	1.53 ns
Crude fibers (%)	107.50***	227.07***	2.99**
Nitrogen (%)	1.62 ns	2.66*	0.95 ns
Phosphorus (%)	541.71***	275.18***	6.19***
Potassium (%)	895.58***	509.70***	6.96***

Numbers demonstrate F-values; ns = non-significant; ** = significant; *** = highly significant.

Table 5. Yield attributes of cowpea as affected by various irrigation levels, fertilizer types, and their interactions.

Fertilizer type	Irrigation water level (%)
	70	80	90	100
	Number of pods (pod plant^−1)
Control	9.62 ± 0.64^g	9.94 ± 0.94^g	10.10 ± 1.08^fg	10.76 ± 1.64^defg
NPK	9.82 ± 0.43^g	10.05 ± 0.33^fg	10.29 ± 0.24^efg	10.47 ± 0.37^efg
Bradyrhizobium sp.	9.95 ± 0.30^g	10.17 ± 0.19^fg	10.34 ± 0.24^efg	10.74 ± 0.44^defg
Complete potato tops	10.37 ± 0.21^efg	11.23 ± 0.13^def	11.95 ± 0.27^cd	12.64 ± 0.45^bc
Chopped potato tops	11.54 ± 0.59^cde	12.65 ± 0.44^bc	13.83 ± 0.41^b	16.90 ± 0.13^a
	Number of seeds (Seed pod^−1)
Control	4.74 ± 0.37^l	5.71 ± 0.77^kl	6.82 ± 0.49^jk	7.87 ± 0.95^ij
NPK	8.79 ± 0.47^hi	9.29 ± 1.00^ghi	10.46 ± 0.65^efg	11.01 ± 1.11^def
Bradyrhizobium sp.	8.89 ± 0.51^hi	9.34 ± 0.94^gh	10.51 ± 0.69^efg	11.05 ± 1.12^def
Complete potato tops	9.49 ± 0.12^gh	10.40 ± 0.37^efg	11.20 ± 0.07^cde	12.08 ± 0.09^bcd
Chopped potato tops	9.73 ± 0.16^fgh	12.38 ± 0.22^bc	13.01 ± 0.01^ab	14.05 ± 0.08^a
	Weight of 100 seeds (g 100 seed^−1)
Control	5.23 ± 0.24^c	5.61 ± 0.56^c	6.08 ± 0.75^d	7.26 ± 1.25^d
NPK	8.00 ± 1.10^b	8.06 ± 1.05^b	8.28 ± 0.85^c	9.06 ± 1.04^c
Bradyrhizobium sp.	8.04 ± 1.11^b	8.16 ± 1.06^b	8.44 ± 0.91^c	9.13 ± 1.00^bc
Complete potato tops	9.09 ± 0.01^a	9.21 ± 0.01^a	9.43 ± 0.02^b	10.09 ± 0.02^ab
Chopped potato tops	9.23 ± 0.05^a	9.62 ± 0.13^a	10.68 ± 0.13^a	11.01 ± 0.02^a
	Seed yield (kg ha^−1)
Control	1028.9 ± 9.7^l	1143.9 ± 10.8^k	1168.7 ± 12.6^jk	1208.3 ± 28.1^j
NPK	1053.3 ± 19.8^l	1479.8 ± 11.3^gh	1520.2 ± 30.3^fgh	1544.3 ± 41.9^f
Bradyrhizobium sp.	1073.1 ± 11.5^l	1496.3 ± 17.1^gh	1526.4 ± 25.2^fg	1557.0 ± 41.8^f
Complete potato tops	1417.5 ± 15.0^i	2089.8 ± 17.6^de	2113.8 ± 21.3^d	2228.0 ± 43.1^c
Chopped potato tops	1475.6 ± 20.4^h	2059.2 ± 20.9^e	2364.6 ± 19.6^b	2781.7 ± 8.5^a

Different letters donate statistically significant differences following Tukey test (p < 5%).

Figure 1. Osmomodulators level of cowpea as affected by various irrigation levels, fertilizer types, and their interactions. Different letters donate statistically significant differences following Tukey test (p < 5%).

Figure 2. Nutritional value of cowpea as affected by various irrigation levels, fertilizer types, and their interactions. Different letters donate statistically significant differences following Tukey test (p < 5%).

Table 6. Vegetative attributes of cowpea as affected by various irrigation levels, fertilizer types and their interactions.

Fertilizer type	Irrigation water level (%)
	70	80	90	100
	Plant height (cm plant^−1)
Control	56.00 ± 4.43^c	57.33 ± 4.13^c	59.50 ± 4.23^d	60.67 ± 4.08^d
NPK	59.83 ± 3.71^b	60.00 ± 3.41^bc	61.83 ± 2.86^cd	63.33 ± 2.66^d
Bradyrhizobium sp.	60.33 ± 2.66^b	61.17 ± 2.48^b	62.67 ± 2.66^bc	63.83 ± 2.64^c
Complete potato tops	60.83 ± 0.75^b	62.33 ± 0.52^b	65.33 ± 1.03^b	66.83 ± 1.47^b
Chopped potato tops	65.00 ± 0.89^a	68.33 ± 0.82^a	70.83 ± 0.75^a	74.50 ± 1.05^a
	Dry biomass (kg ha^−1)
Control	1339.2 ± 180.9^d	1412.6 ± 95.7^e	1440.8 ± 73.9^e	1539.6 ± 81.8^e
NPK	2354.6 ± 96.5^c	2370.3 ± 83.1^d	2428.1 ± 125.1^d	2445.4 ± 113.8^d
Bradyrhizobium sp.	2472.8 ± 9.1^b	2516.0 ± 5.0^c	2559.9 ± 5.6^c	2540.1 ± 29.1^c
Complete potato tops	2520.8 ± 50.5^b	2589.2 ± 30.6^b	2652.1 ± 19.5^b	2692.9 ± 53.8^b
Chopped potato tops	2676.9 ± 55.9^a	2710.0 ± 64.1^a	2783.1 ± 58.2^a	2888.6 ± 67.5^a

Different letters donate statistically significant differences following Tukey test (p < 5%).

Figure 3. Mineral nutrient content of cowpea as affected by various irrigation levels, fertilizer types, and their interactions. Different letters donate statistically significant differences following Tukey test (p < 5%).