Effects of liquid nitrogen fertilizer and Benzyl Amino Purine (BAP) on mineral elements and lipid content in relation to senescence of two cowpea varieties

Abstract

The effects of combined treatment of liquid nitrogen fertilizer and benzyl amino purine (BAP) was studied on mineral elements (Magnesium, Phosphorus, Potassium, Calcium, sodium, iron and Manganese) and lipid content in relation to senescence. The experimental site for this study was situated at the botanical garden of the Biological Science Department of the University of Lagos, Nigeria. The cowpea varieties used for this study were, Kanannado, a local cowpea variety and IT 89KD – 288 an improved variety which are photosensitive, there were four treatments namely nitrogen fertilizer, BAP, combined treatment of liquid nitrogen fertilizer and BAP and then the control, there were 15 replications for each treatment. The procedure involved foliar spray of the plants with liquid nitrogen fertilizer (100ml in 15 liters of water), BAP at 200ppm concentration, combined treatment of liquid nitrogen fertilizer with BAP at 3:1 ratio while the control plants were foliarly sprayed with distilled water, the spray was done at 3, 6, and 9 weeks after planting. The rainy season trial was carried out on the 9^th of August 2012, while the dry season trial was carried out on 20^th January 2013. IT89KD-288 had the highest content of calcium and potassium while Kanannado had the highest content of magnesium, phosphorus, sodium, iron and manganese. While comparison between the treatment showed that the treatment with the highest mineral elements contents such as Phosphorus, Potassium, Calcium, Sodium and Iron in the varieties was the combined treatment of liquid nitrogen fertilizer and BAP (150%N+200ppm BAP), while 200ppmBAP had the highest content of Magnesium and Manganese. 150%N treatment had the highest content of calcium; the control plants had the least content of all the mineral elements. Comparison between the two seasons, the result had shown that there were more mineral elements in the rainy season than in the dry season. With regards to lipid content comparison between the treatments has shown that the variety IT89KD-288 had the highest lipid content at 6 weeks only but at 9 and12 weeks Kanannado had the highest content. Between the treatments, 150% N + BAP had the highest content followed by 150%N at 6 weeks but at 9 and 12 weeks there was more lipid with 200ppm BAP, between the two seasons, there was more lipid in the rainy season than dry season. The significant findings of this study is that the combined treatment of liquid nitrogen fertilizer and BAP (150%N+200ppm BAP) improved the mineral element and lipid content and delay senescence in the two cowpea varieties. Therefore could be recommended for usage to farmers.

Keywords: Cowpea, Benzyl Amino Purine, Lipid, senescence, Fertilizer