Influence of NPK Blended Fertilizer Application on Chlorophyll Content and Tissue Mineral Contents of Two Finger Millet Varieties Grown in Acid Soils of Kakamega, Western Kenya

Abstract

Acidic soils with high exchangeable aluminium ions occur in most parts of Kenya, western Kenya inclusive. Aluminium toxicity is a serious environmental problem that affects crop productivity in Western Kenya region. The county governments of Kakamega, Bungoma, Vihiga, Busia and Trans-Nzoia are promoting the application of NPK blended fertilizer to ameliorate the soil acidity to increase maize production. Finger millet (Eleusine coracana L) is one of the important cereal crops in Kenya and has the ability to grow under unfavorable environmental conditions much better than other cereal crops.  It is for this reason that it is currently being popularized in efforts to address food security in the region, however, the effects of NPK blended fertilizer application on the selected physiological parameters of the crop is little known, hence prompting the study. The objective of this study was to investigate the effect of NPK blended fertilizer application on chlorophyll content index and plant tissue mineral analysis. Randomized Complete Block Design with 0,25,50,75,100 kg application rates per acre of NPK blended fertilizer as the treatments were applied in two equal split applications. The measured parameters were chlorophyll content index using CCM-200 spectrophotometer, (Opti- Sciences Inc., Hudson, USA) from the plant leaves at 50% plot maturity. Motsara and Roy Procedures were used to determine plant tissue analysis for nitrogen, phosphorus, potassium, calcium, and magnesium at physiological maturity from the leaves. Data were subjected to analysis of variance (ANOVA) using GenStat statistical package version 15.1. Means were separated by Least Significant Difference (LSD) test at 0.05 probability level. Regression analysis was used to estimate the relationship between variables. At the 75 kg/acre rate, the leaves showed the significant P<0.05 chlorophyll content, calcium, and potassium in both varieties for the two seasons, short rain, and long rain respectively. Control had the lowest physiological activities for both seasons regarding chlorophyll content, tissue calcium, magnesium, nitrogen, phosphorus, and potassium. Significant nitrogen content was observed on Gulu-E variety for both seasons on the highest rate whereas the same trend was observed on P-224 variety and during the short rainy season, a linear increase was observed with increasing NPK blended fertilizer rates. No conclusive pattern was observed during the short rainy season but with the control exhibiting the lowest phosphorus content for both varieties. A significant response to physiology (chlorophyll and plant leaf tissue mineral) might have been due to increased uptake of mineral nutrients present in the NPK blended fertilizer and increased soil pH caused by the liming action of the NPK blended fertilizer.