Effect of Partial Root-Zone Drying Irrigation and Potassium Fertilizer on Water use Efficiency, Growth and Yield of Cowpea (Vigna Unguiculata L.) in Gypsiferous Soil

A field experiment was carried out to study the effect of partial root-zone drying Irrigation and Potassium on water use efficiency, growth, and yield of Cowpea (Vigna unguiculata L.) in gypsiferous Soil, at the experimental station of the College of Agriculture, Tikrit University, located at 34°40 49 and 43° 38 40 longitude and 129m above sea level. The experiment was conducted with a randomized complete block design (RCBD) with two factorial combinations, irrigation and potassium fertilizer. the first treatment, irrigation with 100% water requirement, was added to two sides of the root zone along the growth season. Second irrigation treatment with 50% water requirement alternately for each side during the growth season. Third irrigation treatment requires 50% of the water requirement for one side of the growth season. The second factor was potassium fertilizer which added the doses 0, 100, 200, and 300 kg k ha-1 for each treatment. the best results were. The highest water consumption was1163.50 mm season-1 with full irrigation treatment, the lowest water consumption was566.45 mm with alternative partial zone irrigation, and the treatment of full irrigation with 300 kg k ha-1 give the highest results in seeds.pod-1, number of pods.plant-1, Pods Wight, plant (vegetative part), root weight, and Seed yield. highest water use efficacy was 1.69 % with alternative partial zone irrigation and 300 kg k ha-1.