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Abstract Two field experiments were carried out in the Desert Research Center Station at Maryut, Alexandria governorate, during the two successive summer seasons to study the effect of N, K and P fertilizer levels on growth and yield and its components as well as mineral content and chemical composition in both seeds and straw of cowpea plants (Vigna sinensis, L. var. Kareem 7). This investigation included 27 treatments which were the individual and the mutual effect of three levels of N~ K and P fertilizers. The following is a summary of the most important reesults: I. Growth characters : 1. There were a significant effect on the studied growth characters by adding nitrogen level treatments. The highest values were obtained by using 45 kg N/fed. Also, the highest values of plant height, number of branches/plant, number of leaves/plant, fresh weight/plant and fresh forage yield/fed. were obtained at ls1. cut in the 2nd.. season (1994). Whereas, leaves dry weight/plant. LAI and plant dry weight were superior in tst. cut at lsi. season (1993). 2. Growth characters were significantly affected by the appliction of potassium fertilizer levels. In this respect, the best treatment was 48 kg K20/fed. Maximum values of plant height, number of branches/plant, leaves number/plant, plant fresh weight as well as fresh and dry forage yield/fed .. were obtained at 1st.. cut in 2nd.. season (1994). While, the highest values of leaves dry weightlplant, LAI and plant dry weig.ht were achieved at tst, cut in 1st.. season (1993). 3. Application of phosphorus fertilizer levels resulted in a significant responses of all growth characters of cowpea plants. The favourable 134 treatment for the highest values was 45 kg P205/fed. In this conection, plant height, number of branches/plant, number of leaves/plant, plant fresh weight as well as fresh and dry forage yields/fed. reached its maximum values at 1st. cut in 2nd. season (1994). Also, maximum values of leaves dry weight/plant, LAI and plant dry weight were obtained at 1st. cut in 1st. season (1993). 4. The interaction between nitrogen and potassium had a significant effect on the studied growth characters. Application of 45 kg N/fed. + 48 kg K20/fed. treatment gave the highest values of plant height, number of branches/plant, number of leaves/plant, plant fresh weight and fresh and dry forage yields/fed., at 151.cut in 2nd.. season (1994). Whereas, leaves dry weight/plant, LAI and plant dry weight were superior at tst cut in both seasons (1993 and 1994). Whereas, the highest responses were at 151. season (1993) for both leaves dry weight/plant and plant dry weight. Plant fresh weight at 2nd. season, fresh forage yield/fed. at 1st. cut in 2nd.. season, also reached to its maximum values by adding (45 kg Nzfed, + 48 kg K20/fed.) treatment. 5. Growth characters differes in the response to the interaction treatments between nitrogen and phosphorus. Generally, the best treatment was (45 kg N fed.+ 45 kg P205/fed.). The highest values of both number of leaves/plant and plant dry weight were obtained at both the two seasons (1993 and 1994). While the highest value of plant height, plant dry weight and plant fresh weight were obtained at tst. season (1993) and 2nd.. cut in 2nd. season (1994). Also, there were a significant response for fresh forage yield/fed. at 1st. season (1993) only. Number of branches/plant and I..AI were significantly responded at 2nd.. cut in 2nd.. season (1994) and at tst. and 2nd.. cuts in 2nd. season (1994), respectively. |