EFFECT OF POTASSIUM FERTILIZERS ON THE QUALITY AND QUANTITY OF FOUR VARIETIES OF COWPEA CROP (Vigna unguiculata L. walp.)

Abstract

This experiment was conducted in the field of College of Agriculture – University of Diyala during the season 2013 to assess the performance of four varieties of cowpea (Black eye, Ramshorn, Local and Rhaoah) and the effect of adding potassium fertilizer in the form of potassium sulfate of three levels of potassium (0.160, 320) kg h-¹ in the quality and quantity of yield by using split plots in RCBD .The significance of differences between means were tested by using H.S.D. test at 0.05 level of probability. The results of study showed a significant difference in the performance of the varieties. The local variety was superior in plant yield, crop area and the average weight of pod highest values reached 1384.00 gm plant-1, 20.94 tons h-1 and 7.30 g respectively. The variety of Rhaoah was superior in the average number and the length of pods and the ratio of nitrogen and protein in seeds. The difference between varieties was not significant in the average number of pod seeds. The effect of adding potassium fertilizer was significant. The addition of potassium level in 320 kg h-1 was significant in plant yield and crop area increase from the comparison in 24.47% and 24.75% respectively, in addition to the ratio of potassium in the seeds and the number of pods. The level of comparison in the ratio of nitrogen and protein in the seeds was superior. The interactions between varieties and potassium levels were not significant for all the varieties.