Browsing by Author "Njinju, Symon Mugo"

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    Effects of Nitrogen Fertilizer on Yields and Quality of Selected Rice Varieties at Mwea Irrigation Scheme, Kirinyaga County, Kenya
    (Kenyatta University, 2018-11) Njinju, Symon Mugo
    Rice is a staple food and the main source of calories and proteins for more than half of the world population. Its increasing demand in Africa made it a commodity for food security and poverty reduction. Rice ranks third in Kenya’s staple food after maize and wheat. Its consumption has been growing rapidly due to urbanization and changing eating habits in both rural and urban households. In 2014, local rice production was estimated at 129,000 metric tonnes, while consumption was 548,000 metric tonnes. Increased production is required in order to meet the huge deficit. Similar to other countries, yield of rice in Kenya can be increased by selecting appropriate high yielding varieties and conducting appropriate cultivation practices particularly planting time and nitrogen management which in addition is thought to impact on grain quality. The objective of the study was to investigate the effect of Nitrogen fertilization on growth, yields and quality of three rice varieties namely Basmati370, BW196 and IR72. Field experiments were conducted at Kirogo Farm in KALRO Mwea, Kirinyaga County in two seasons. The first season was from the month of February to June, 2014 while the second season was from January to June, 2015. The trial was a split plot arrangement in a randomized complete block design (RCBD) replicated three times. Rice varieties (Basmati370, BW196 and IR72) formed the main plot while fertilizer rates (75 Kg N ha-1, 125 Kg N ha-1, 175 Kg N ha-1 and 225 Kg N ha-1) were the sub-plots. Soil sampling was done before planting in order to establish the Nitrogen status of the site. Parameters examined were plant height, tiller number, Soil-plant analysis development (SPAD) value, filled grain ratio and yield components. Grain quality was determined by proximate analysis. The data was subjected to Analysis of Variance using SAS version 8.2 statistical package. The results indicated that the shoot dry weight, SPAD and total grain number increased while the grain yield did not increase as the N-fertilizer was increased. The filled grains decreased with increase of the fertilizer. There were lower yields in season two due to low temperatures at grain filling. The percent crude proteins in the milled grains increased while crude oil decreased with increase of nitrogen. There was no significant difference in grain quality between the three rice varieties though BW196 (6.95%) had the highest crude proteins followed by Basmati370 (6.80%) and IR72 (6.72%), respectively. This study showed that it is possible to increase grain yield, yield components and quality by increasing Nitrogen fertilizer amount with appropriate management. Different varieties need Nitrogen at different times while Basmati370 and BW196 are susceptible to cold weather. Further work is necessary to address these findings. This information will be useful to the researchers for recommendation to the farmers in order to improve on rice cultivation for increased yields and income at household level in Kenya
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    Physiological, morphological and biochemical responses of sorghum varieties to progressive water stress and rehydration in Siaya And Baringo Counties, Kenya
    (Kenyatta University, 2025-02) Njinju, Symon Mugo
    Sorghum bicolor (L.) is an important food crop worldwide after maize, wheat, rice and barley. In Kenya, it is grown on an estimated 184,654 ha supporting over 25% as food and 26% as livestock feed. Despite having rich diversity in Arid and Semiarid Lands (ASALs), its production has been below the optimum mainly because of the abiotic stresses, with drought being the major stress. Drought is an impediment to sorghum productivity because it leads to water stress in the plant lowering its productivity. Drought tolerance enhancement under arid environments is a process that involves a mechanism of maintaining plant water status in order to increase grain yield and quality. A study was conducted with the objective of evaluating critical growth and phenological stages of sorghum sensitive to progressive water stress and rehydration in Siaya and Baringo counties where: (1) A field survey to acquire sorghum accessions was conducted in Siaya and Baringo counties; (2) Field experiments conducted in Siaya and Baringo counties to evaluate sorghum accessions for drought tolerance and (3) Selected sorghum varieties evaluated for physiological and biochemical responses to progressive water stress and re-watering in a greenhouse at KALRO Mwea. The field experiments were Randomized Complete Block Design (RCBD) with 15 accessions, two moisture levels in three replications in Siaya and Baringo sites. A controlled greenhouse pot experiment was conducted at KALRO Mwea constituting five stress levels (well-watered; continuous stress, pre anthesis, anthesis and post anthesis), four varieties in three replicates in two soil types collected from Baringo and Siaya. Stress was induced after crop establishment and re-watering done after each stress episode. Growth and phenological data on proline, chlorophyll content, soil moisture, stomata conductance, yields and grain quality were collected appropriately. Survey data was analysed using Statistical Package for Social Scientists (SPSS V 25). Field data was analyzed using R software version 4.2. Treatment means were separated using Tukey Honestly significance difference (Tukey HSD) at 5%. Results indicated that farmers used local seed accessions (46.5%), preferred sorghum traits included drought tolerance, disease and pests resistance. Varieties response to re- watering after prolonged stress duration differed significantly. The grain weights, plant height, SPAD values, shoot dry weight and grain weight were highly significant in both Baringo and Siaya soil types. Results from the two sites indicated that there were significant differences on number of days to anthesis (IH and 50%H), total filled grains (TFGW), total grain weight (TGW), grain number panicle-1 (GPnW) and shoot dry weight (SDW) in varieties within sites at p<0. The results showed that stress for a short duration up to Vegetative stage followed by re-watering recorded significantly low proline and other amino acids accumulation under both Baringo and Siaya soil. Gadam and Nyagem varieties recorded higher yields under stress conditions in Siaya site (p<0.05). The Nyagem and Gadam varieties are recommended to farmers in ASALs for increased food security, income and better livelihoods. The physiological and biochemical properties were elevated in case of drought tolerant varieties and this can be used as rapid indicators for sorghum selection for growth in ASALs.