Browsing by Author "Ngeno, J."

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Effect of Rhizobium inoculation and nitrogen fertilizer application on growth, nodulation and yield of two garden pea genotypes.
(FACT Limited, 2012) Ngeno, J.; Chemining’wa, G.N.; Muthomi, J.W.; Shibairo, Solomon I.
Nitrogen is the most limiting nutrient in smallholder garden pea farms in Kenya and can be corrected by application of inorganic fertilizers and Rhizobium inoculation. A study was conducted to compare the effects of Rhizobium inoculation and nitrogen fertilizer application on nodulation and yield of two garden pea varieties grown for local (variety Plum) and export (variety Ambassador) markets. Field experiments were conducted at University of Nairobi's Field station in 2007 short and long rains. Varieties Plum and Ambassador were either inoculated with a commercial strain of Rhizobium leguminosarum bv. viciae, supplied with 30 or 60 kg N ha-1 or without any treatment. Inoculation and N-fertilizer enhanced shoot dry matter, but had no effect on grain yield. Plots receiving 60 kg N ha-1 intercepted more photosynthetically active radiation than non-treated control plots. Rhizobium inoculation increased number of active nodules and nodule dry matter. Plum variety accumulated more nodule and shoot biomass than Ambassador. Variety Ambassador had longer and more seeds per pod than Plum while the converse was the case in number of pods plant-1. Nodulation observed in control plots indicated that native pea rhizobia in Kabete soils are compatible with Plum and Ambassador garden pea varieties. Rhizobia inoculation of garden pea can yield similar shoot biomass as nitrogen application. Nitrogen fertilizer increased shoot dry matter, leaf area index and PAR interception by garden pea. Increases in above ground biomass and nodulation due to rhizobia inoculation and nitrogen fertilizer application were not translated into increased pod and grain yield. Growth and nodulation responses to inoculation and nitrogen fertilization were dependent on the garden pea genotype, hence the need to investigate the differential response of Plum and Ambassador. It is suggested that a study be conducted to determine the effect of Rhizobium inoculation and nitrogen fertilization on a broad range of locally grown garden pea genotypes.
Effectiveness of indigenous pea rhizobia (Rhizobium leguminosarum bv. viciae) in cultivated soils of central Kenya
(J. Appl. Biosci., 2012-09-30) Chemining’wa, George N.; Ngeno, J.; Muthomi, J.W; Shibairo, Solomon I.
Objective: This paper reports on a study conducted to determine the effectiveness of pea rhizobia (Rhizobium leguminosarum bv. viciae) resident in Central Kenyan soils. Methodology and results: Garden pea (Pisum sativum cv. Plum) grown in pots containing soils collected from 26 sites, with and without a history of pea cultivation, in central Kenya was inoculated with a commercial rhizobial strain, supplied with 74 mg N pot-1, or did not receive any treatment (control). Rhizobial inoculation enhanced pea nodule numbers in soils from some sites that had no history of pea cultivation. Nitrogen fertilizer depressed pea nodulation in soil samples from all sites. Most abundant active and total nodules (20 and 22 nodules plant -1) were recorded in sites with adequate soil N, high organic carbon and history of pea cultivation In many cases, plants in untreated soils had a high nodule number and accumulated more shoot biomass than plants growing in inoculated or nitrogen supplied soil. This confirmed the N2 fixation efficiency of indigenous pea rhizobia strains. Plants that had poor nodule formation were those growing in soils from a site in Nyeri that was low in soil N and organic carbon. . Conclusion and application: Most soils in Central Kenya have abundant and efficient native strains of pea rhizobia irrespective of pea cultivation history. In some sites, indigenous rhizobia out-performed the commercial inoculant strain. Thus, it is advisable to screen indigenous pea rhizobia strains in the target sites for N2 fixation efficiency with the objective of making more effective inoculants. Improvement in soil organic carbon in Central Kenya can enhance the benefits accruable from pea N2 fixation. A similar study involving a broad range of pea genotypes and strains of Rhizobium leguminosarum bv. viciae is recommended.