Browsing by Author "Njeru, E. M."

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    Contrasting effects of cover crops on ‘hot spot’ arbuscular mycorrhizal fungal communities in organic tomato
    (Springer Verlag, 2014) Njeru, E. M.; Avio L.; Bocci G.; Sbrana C.; Turrini A.; Bàrberi P.; Giovannetti M.; Oehl F.
    Arbuscular mycorrhizal fungal (AMF) communities are fundamental in organic cropping systems where they provide essential agro-ecosystem services, improving soil fertility and sustaining crop production. They are affected by agronomic practices, but still, scanty information is available about the role of specific crops, crop rotations and the use of winter cover crops on the AMF community compositions at the field sites. A field experiment was conducted to elucidate the role of diversified cover crops and AMF inoculation on AMF diversity in organic tomato. Tomato, pre-inoculated at nursery with two AMF isolates, was grown following four cover crop treatments: Indian mustard, hairy vetch, a mixture of seven species and a fallow. Tomato root colonization at flowering was more affected by AMF pre-transplant inoculation than by the cover crop treatments. An enormous species richness was found by morphological spore identification: 58 AMF species belonging to 14 genera, with 46 and 53 species retrieved at the end of cover crop cycle and at tomato harvest, respectively. At both sampling times, AMF spore abundance was highest in hairy vetch, but after tomato harvest, AMF species richness and diversity were lower in hairy vetch than in the cover crop mixture and in the mustard treatments. A higher AMF diversity was found at tomato harvest, compared with the end of the cover crop cycle, independent of the cover crop and pre-transplant AMF inoculation. Our findings suggest that seasonal and environmental factors play a major role on AMF abundance and diversity than short-term agronomic practices, including AMF inoculation. The huge AMF diversity is explained by the field history and the Mediterranean environment, where species characteristic of temperate and sub-tropical climates co-occur.
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    Managing Soybean for Enhanced Food Production and Soil Bio-Fertility in Smallholder Systems through Maximized Fertilizer Use Efficiency
    (Scientific & Academic Publishing, 2013) Njeru, E. M.; Maingi, J. M.; Cheruiyot, R.C.; Mburugu, G. N.
    The production of promiscuous soybean by smallholder farmers in Kenya would improve soil fertility through biological nitrogen fixation (BNF), boost food security, and contribute to generation of cash. The present study was conducted to determine the effects of soil amendments on growth and yields of promiscuous soybean cultivars under varying soil carbon levels. Field experiments using early maturing SB 19 and late maturing SB 20 promiscuous soybean cultivars and different levels of phosphorus (P), potassium (K) and sulphur (S) fertilizers were conducted in two sites in the south-eastern slopes of Mt. Kenya, approximately 1500 m above sea level. The soybean cultivars were observed for phenology, plant biomass production, pod fresh weight, 1000 seed weight and haulm weight. Significant differences were observed on most yield components due to field carbon level, soybean cultivar and fertilizer amendments, while the plant height was only affected by fertilizer application and soy bean cultivar. However, the effects due to the interaction of these factors were not significant. Therefore, the benefits of combined use of BNF by soybean and application of PKS fertilizers could be a promising entry point into maximized fertilizer use efficiency by smallholder systems in Kenya.
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    Molecular Identification and Antibiotic Susceptibility Patterns of Bacterial Isolates from Urine Samples of African Buffalo, Eland and Cattle
    (International Journal of Applied Biology, 2021-07-03) Musonye, H. A.; Njeru, E. M.; Hassanali, A.; Langata, L. M.; Nonoh, J.
    Presence of antibiotic resistant bacteria in natural environment is an escalating risk of serious implication on human and animal health. Livestock and wildlife have been long recognized as reservoirs for antibiotic resistant bacteria. Nonetheless, there is limited knowledge regarding the potential of livestock and wildlife urine to act as transmission corridor for the spread of antibiotic resistant bacteria. The present study aimed at evaluating antibiotic susceptibility patterns and molecular identification of bacteria isolated from livestock and wildlife urine samples. A total of 19 different bacteria isolated from urine samples of African buffalo, eland and cattle were subjected to antibiotic susceptibility test. The isolates showed diverse susceptibility patterns against co-trimoxazole, tetracycline, amoxycillin, ciprofloxacin, streptomycin, nalidixic acid, chloramphenicol and gentamicin. Of the tested isolates, 73.7 % were exhibited resistance while 31.6 % were intermediate to the range of antibiotics tested. High resistance prevalence to amoxicillin (58%), tetracycline (26 %) and cotrimoxazole (11%) by the tested bacteria was observed. This study reveals the bacteria associated with African buffalo, eland and cattle urine as potential candidates for antibiotic resistance. This information demonstrates the need for measures to be adopted to limit the presence of antibiotic resistant bacteria in wildlife and livestock reservoirs.
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    Response of micropropagated tissue culture banana (Musa spp.) to acclimatization using arbuscular mycorrhiza fungi
    (African Journal of Pure and Applied Sciences, 2023-11-17) Wahome, C. N.; Ombori, O.; Maingi, J.; Njeru, E. M.; Nchore, S. B.; Kimiti, J. M.; Muthini, M.
    The production of banana seedlings through tissue culture provides a reliable source of numerous, disease free, quality plantlets. However, the micropropagation process is faced with a number of challenges. In this study we are focusing on the improvement of survival and growth of the resultant plantlets during the acclimatization process. The viability of arbuscular mycorrhiza fungi (AMF) symbiont in the acclimatization process was assessed. Tissue culture bananas (Kienyeji, Kiganda and Ng’ombe local cultivars) were inoculated with single species AMF Rhizophagus irregularis and Funneliformis mosseae as well as commercial AMF Rhizatech. The survival rate was assessed and plant growth evaluated at a two week interval. Destructive harvesting was conducted followed by assessment of root, shoot and total biomass. The results demonstrated that Kiganda treated with Rhisophagus irregularis and Funneliformis mossae recorded better survival rates compared to treatments with NPK fertilizer and commercial AMF (Rhizatech). Kienyeji cultivar however had a better survival rate when treated with commercial AMF (Rhizatech). Ng’ombe cultivar was very resilient having 100 % survival rate when treated with indigenous AMF, commercial AMF (Rhizatech) and NPK. There were significant differences in the shoot dry weight, root dry weight and biomass in the three banana cultivars. Kiganda and Kienyeji cultivars had the highest biomass when treated with Funneliformis mossae of 0.52 g and 0.83 g respectively. The results in this study confirm that the use of AMF in the acclimatization process improves the overall seedling output of the micropropagation process during the nursery stage of production.