Tropical highland conditions in Mwea Kenya, ensure the high radiation and the large day-night temperature differences. Such conditions are generally believed to promote rice growth and yield, but the current grain yield is lower than the expectation. In the current standard N fertilizer practice in Mwea, 75 kg nitrogen (N) ha −1 is applied in three splits at fixed timing. The effects of increases in N fertilizer amount (125, 175, and 225 kg N ha −1) on rice growth and yield were evaluated to test the hypothesis that unachieved high rice grain yield in Mwea is due to insufficient amount of N fertilizer. Two popular lowland varieties in Mwea (Basmati 370 and BW196) and two varieties reported as high yielding at other countries (Takanari and IR72) were used. Shoot dry weight (DW) increased with increases in the amount of N fertilizer applied in three splits at fixed timing, irrespective of variety. It reached approximately 20 t ha −1 under increased N conditions (>75 kg N ha −1) in several cases, indicating that high biomass production could be achieved by increasing N application rate. However, the increased biomass did not increase grain yield, due to decreased grain filling under high N conditions in all varieties. Thus, N amounts above 75 kg ha −1 were ineffective for increasing grain yields in Mwea, where N fertilizer was applied in three splits at fixed timing. Increasing influence of low temperature under high N conditions may be one of the reasons for the decreased grain filling in Mwea.

This study aims to evaluate the efficacy of nitrogen (N) forms: ammonium, nitrate, and urea on maize performance, N uptake and use efficiency, and the grain protein content. The experiment was laid out as a split-plot with the whole plot factor being the three fertilizer treatments and the subplot being four N levels (0, 25, 50, and 100 kg N ha −1 ) with three replicates. Plant tissues were analyzed for total N uptake. Grain and stover yields and grain protein were determined at maturity. The highest (62 cm) plant height (at the vegetative stage) was recorded in nitrate treatment. Grain yield was highest (2.9 t ha −1 ) in plots that received nitrate. Fertilization with nitrate enhanced grain protein more (11.6%) than when urea or ammonium was used. N uptake was highest (42 kg N ha −1 ) under ammonium treatment, intermediate (22 kg N ha −1 ) in those treated with nitrate, and lowest (21 kg N ha −1 ) in urea-receiving plots. Application of 25 kg N ha −1 resulted in the least N uptake efficiency with optimal values registered at 50 kg N ha −1 . Agronomic N use efficiency differed among the rates with values ranging from 44 to 183 t ha −1 per N kg ha −1 applied in the order of 25 < 50 < 100 kg N ha −1 . This study showed that for optimal growth, productivity, and nutritional benefits, maize ought to be grown using nitrate N form at the rate of 50 kg N ha −1 .Keywords Nitrogen (N) fertilizer sources . N forms . N use efficiency indices . Grain protein content * Harun I. Gitari

This study was carried out to investigate the influence of phosphorus fertilizers on the concentrations of nutrients, particularly calcium, protein, zinc, and iron in finger millet grains grown in different agro-ecologies in Kenya. The on-station experiments were carried out at Kiboko (Eastern Kenya), Kakamega, and Alupe (Western Kenya) in 2015 during the short and long rainy seasons. The trials were laid out in a randomized complete block design (RCBD) in a 4 × 3 factorial arrangement with three replicates. The treatments comprised of four levels of phosphorus (0, 12.5, 25.0 and 37.5 kg ha −1 P 2 O 5) and three finger millet varieties (U-15, P-224 and a local variety). Application of phosphorus significantly (p ≤ 0.05) increased the protein content of finger millet grain in varieties in all the three sites. Variety U-15 had the highest protein content (11.0%) at 25 kg ha −1 P 2 O 5 with the control (zero P) on variety P-224 eliciting the lowest (4.4%) at Kiboko. At Kakamega, the 25 kg ha −1 P 2 O 5 treatment with U-15 variety had the highest protein content (15.3%) while the same variety at 12.5 kg ha −1 P 2 O 5 rate elicited the highest protein content (15.0%) at Alupe. Phosphorus application significantly enhanced the nutritional quality of finger millet grains specifically protein, calcium, iron, and zinc. Variety P-224 had the highest calcium content in all sites and highest iron content at Kakamega while the local varieties had the highest zinc content in all sites. The varieties responded differently to each quality component but generally, based on the protein content, the 25 kg ha −1 P 2 O 5 is recommended.

Abstract:Finger millet is one of the potential cereal crops that can contribute to the efforts of realization of food security in the Sub-Saharan Africa. However, scientific information available with regards to improving soil phosphorus supply and identification of P efficient varieties for the crops potential yield is limited. In order to investigate the effects of P levels on yield components and grain yield On-station field experiments were conducted in two sites of western Kenya during the long and short rain seasons of 2015. The experiment was laid out in a Randomized Complete Block Design in factorial arrangement with four levels of P (0, 12.5, 25 and 37.5 kg P 2 O 5 ha -1 and three finger millet varieties (U-15, P-224 and a local check-Ikhulule) and the treatments replicated three times. The increase of phosphorus levels significantly (P≤0.05) increased the grain yield over the control up to 25 kg P 2 O 5 ha -1 during the long rain seasons and 25 kg P 2 O 5 ha -1 during the short rain seasons in both sites. Interactions at P≤0.05 were revealed on the grain yield where improved variety P-224 at 25 kg P 2 O 5 ha -1 produced the highest grain yield of 4.74 t.ha -1 in Alupe and 4.77 t.ha -1 in Kakamega and the consistent results suggest that the combination is highly recommended. Therefore the use of judicious and proper rates of P fertilizers can markedly increase the grain yield of finger millet in western Kenya.

HighlightsLow response to Rhizobia inoculation observed in soil with low available C and N.Legume fertilizer blend did not enhance nodulation in soil of very low available N.Vermicompost amendment gave higher nodulation, nodule occupancy, nitrogen uptake.Vermicompost yield higher biomass & grain yield in greenhouse and field trials.

Green pepper production based on the package of recommendations developed has not given the desired growth and yield performances in the world and specifically Kenya. Information is required with which to evolve the agronomic practices that will be adopted to maximize yield in green pepper production. Great attention should be paid when selecting the most appropriate spacing where there are very few reports and limited information regarding plant spacing in cultivation of the crop under the agro-climatic conditions of Kenya. Therefore, a field study was carried out at the Alupe Research Station, Busia County, to evaluate the growth and yield responses of green pepper under three row plant spacings namely: 50x40 cm, 40x40 cm and 30x40 cm during the long and short rainy seasons of 2015. The experiment was set up in a randomized complete block design with three replicates. The treatment effects were measured on plant growth for 12 weeks and ripe fruit yield parameters which were later cleaned statistically analyzed. The plant spacing had significant variation in almost all the growth and yield components except the fruit length. In

Aims: The aims of this study were to investigate water stress effect on total phenolics and total antioxidants of selected African nightshades and determine any possible variations in the amount of total phenolics and total antioxidants among the accessions grown. Study Design: Study was conducted on the basis of randomized complete block design. Place and Duration of Study: The study was carried out in Kenyatta University Agricultural farm in Kiambu County of Kenya. Greenhouse experiments were carried out in the same farm. Methodology: A greenhouse and field experiment was conducted to investigate effects of water stress on total phenolic and total antioxidant contents of Solanum scabrum and Solanum villosum. The two African nightshades were subjected to different soil water tensions of 15cbars, 50cbars and 85cbars. After a month of transplanting, samples from the different blocks were collected fortnightly and prepared for total phenolic and total antioxidant determination.

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