Effect of irrigation systems on the growth parameters of cowpea (Vigna unguiculata L. Walp) cultivars in N’Djamena city, Chad

The study was conducted during the winters of 2021 and 2022 at the research farm of the Higher Teachers Training School of N’Djamena, Chad. The aim of the present investigation is to evaluate the growth and productivity traits of four cultivars of cowpea plant (white, black, red, and versicolor) in response to two different irrigation periods (3 and 6 days). The experiment is a factorial with four cowpea cultivars (White, Black , Red and versicolor) in the main plot in a Randomize Complete Block Design (RCBD) and irrigation intervals (3 and 6 days) as the subplot with three replications. Our data demonstrated that the black variety was much superior in leaf surface area (15942.37 cm2), wet weight (343.75 g), dry weight (96 g), number of pods (71.50), weight of pods (137.50 g), number of seeds (475), and total productivity was 2.47 tons/ha. On the other hand, the versicolor variety was superior in the plant height (197 cm), number of leaves (138.75), pod length (15.50 cm), number of seeds in the pod (8.25), while the white variety had the highest average weight for 100 seeds (26.30 g). The same results also, indicated that the irrigation rate for three days was better than that for six days in terms of plant height (162.75 cm), number of leaves (108.37), leaf surface area (12553.72 cm2), wet weight (309.37 g), dry weight (73.25 g), pod length (14.50 cm), weight of seeds per pod (72 g), number of seeds per plant (241.50) and the productivity was 1.29 tons/ha. Finally, the study suggests planting the black and versicolor varieties in N'Djamena city during winter season in order to get the maximum yield by surface irrigation every three days.