Browsing by Author "Kanya, J. I."
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Item Azolla Fern in Mwea Irrigation Scheme and Its Potential Nitrogen Contribution in Paddy Rice Production(Canadian Center of Science and Education, 2019-11) Oyange, W. A.; Chemining’wa, G. N.; Kanya, J. I.; Njiruh, Nthakanio P.Azolla fern is invasive in Mwea Irrigation Scheme in Kenya and its management in paddy rice fields is a challenge to farmers. A survey was undertaken to establish farmer’s knowledge and potential nitrogen contribution by Azolla in the paddies. The Scheme was stratified into seven sections and a questionnaire administered to 250 farmers. Data were collected on awareness levels, source, trend of infestation, abundance, fertilizer regimes and management practices. Five farms from each of the sections were also sampled for Azolla coverage and tissue N levels analyzed. Survey data were analyzed using SPSS software and interpreted using descriptive statistics. Biomass sampling data were analyzed using SASS and means separated using the least significant differences at P ≤ 0.05. The results demonstrated that Azolla has infested nearly all the paddy farms in Mwea. Azolla invasion occurred more than 10 years ago and coverage per unit area was on a decline and stood at 25%. Water shortage and herbicide use were the main reasons associated with this trend. Azolla is conspicuously noticed at transplanting and weeding times. The presence of Azolla in Mwea is enhanced by widespread use of P and K fertilizers and continuous paddy cropping, thus providing a suitable environment for Azolla growth. Azolla was reported to enhance soil fertility, rice yield and yield components. The maximum Azolla biomass coverage was 14.92 t/ha, with a potential nitrogen contribution of 37.6 kg N/ha. Azolla is invasive in Mwea, widespread, beneficial to paddies and with high potential N contribution.Item Effect of time of Azolla incorporation and inorganic fertilizer application on growth and yield of Basmati rice(Academic Journals, 2020-03) Oyange, W. A.; Chemining’wa, G. N.; Kanya, J. I.; Njiruh, Nthakanio P.Azolla tissue contains 5% N, which is slowly released into the soil upon decomposition. Timing of incorporation is therefore important for maximum benefit to a crop. The effect of time to incorporate Azolla biomass on growth and yield of rice was investigated in Mwea-Kenya. Treatments consisted of 7.5 t ha -1 Azolla applied at 21 days after transplanting (DAT) and 30 kg N ha Azolla biomass applied at transplanting, 7.5 t ha -1 inorganic N applied in splits at O, 21 and at 55 DAT. There were control treatments without Azolla and without inorganic N application. The treatments were laid out in a Randomized Complete Block Design (RCBD) with three replications. Phosphorus and potassium were applied at 50 Kg ha -1 each as P2O5 and K2O. Plant height and tiller numbers were recorded at 21 (rooting/tillering), 32 (tillering), 42 (maximum tillering), 60 (flowering) and 75 DAT (heading) while yield parameters were determined at physiological maturity (120 DAT). Data were analysed using SAS software and means separated using the least significant difference test (p≤0.05). Azolla incorporation at transplanting significantly enhanced panicle m -1 , grain weight and grain yield while incorporating it at 21 DAT only significantly enhanced panicle m -2 . Higher environmental temperatures enhanced Azolla effect. The effect of Inorganic N significantly increased plant height, tiller number, grain weight and spikelets panicle -2 -1 . However, percentage grain filling was reduced. The effect of interaction between Azolla application and inorganic N was significant on spikelets panicle and grain weight. Observations therefore indicate that the effect of Azolla on yield and yield components was more when incorporated at transplaItem Morphological and Molecular Characterization of Azolla Accessions in Kenya(Tropical and Subtropical Agroecosystems, 2020-05) Oyange, W. A.; Kanya, J. I.; Chemining’wa, G. N.; Njiruh, Nthakanio P.Background. Azolla Lam., a mosquito fern, is invasive in major rice growing Schemes in Kenya, where it clogs irrigation canals and forms dense mats in paddy fields. However, the species of Azolla has not been established. Objective. to characterize Azolla accessions collected from six major rice Irrigation Schemes in Kenya: Mwea, Ahero, West Kano, Bunyala, Taveta and TARDA. Methodology. Azolla accessions were collected, grown for 10 days at Mwea Irrigation Agricultural Development Centre (MIAD) and their vegetative traits examined microscopically using 13 Pereira’s morphological characters. The vegetative characteristics were evaluated on a binary 0/1 system, pairwise similarity was estimated using Jaccard’s coefficient (S1) and a dendrogram generated. Genomic DNA was extracted from each of the accessions, amplified with SCAR primers and amplified products resolved and scored using agarose gels. Polymorphic SCAR markers were identified and correlated to the accessions. Results. Nine vegetative characters useful for distinguishing between the two Azolla sub-genera (Euazolla and Rhizosperma) and the seven Azolla species were examined. Possession of hook-like, septate glochidia suggested the presence of Azolla filiculoides in TARDA1 accession. The presence of pinnate sporophyte with septate rhizome papillae and fronts measuring 2-4 cm with 2-4 cm long roots and lack of anthocyanin suggested the presence of Azolla nilotica for TARDA 2 and Taveta 2 accessions. SCAR marker based 490 bp primers that identify with A. filiculoides also amplified Mwea and Taveta 1 accessions to give a distinct band. Implications. Results suggest the existence of Azolla nilotica and Azolla filiculoides among the Kenyan accessions. Conclusion. Azolla filiculoides and Azolla nilotica are the two main Azolla species characterized in the major Irrigation Schemes in Kenya. Of the two species, Azolla filiculoides has infested four of the Kenya irrigation schemes (Mwea, Ahero, Bunyala, Tana River and West Kano), while Azolla nilotica exists only in Taveta and TARDA.