ANTI-NUTRITIONAL FACTORS OF TWO COWPEA VARIETIES AS INFLUENCED BY IRRIGATION INTERVAL AND PHOSPHORUS APPLICATION RATES IN ZARIA, NIGERIA

Abstract

A field experiment was conducted to evaluate the effects of irrigation intervals and phosphorus application rates on anti-nutritional factors of two cowpea varieties during 2018 and 2019 dry season. The experiment was laid out in a 2×3×3 factorial arrangement in a split plot design with three replications. Treatments consisted of 2 cowpea varieties (SAMPEA 14 and 15), 3 flood irrigationintervals (5, 10 and 15-days) and 3 phosphorus (P) rates (0, 20 and 40kg/ha), respectively. Results indicated that higher (P<0.05) saponin and phenol contents were recorded with respect to Sampea 15 haulm variety compared to Sampea 14 variety of cowpea haulm. Irrigation interval of 15 days led to higher phenol and oxalate concentration compared to frequent irrigation intervals (5 days). The phenol and oxalate concentrations increased by 18.0% and 23.7%, respectively in the longest irrigation interval as compared to the shortest irrigation interval. It was therefore, concluded that farmers should irrigate SAMPEA 14 using the 5 day irrigation interval in combination with 20 kgP/ha of phosphorus application rate for optimum cowpea haulm quality.