Agronomy

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Browsing Agronomy by Funder "JKUAT"

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    Effect of Biological Control Antagonists Adsorbed on Chitosan Immobilized Silica Nanocomposite on Ralstonia solanacearum and Growth of Tomato Seedlings
    (SCIENCEDOMAIN international, 2016-01-11) Gatahi Dennis; Wanyika Harrison; Kihurani Agnes; Gatebe Erastus
    Background: Biological control holds promise in managing bacterial wilt disease. However, its efficacy is limited by harsh environmental conditions when applied without use of suitable carrier materials. Aim: The study entailed synthesis of nanocarrier materials for biological control agents (BCAs) using Chitosan and silica nanocomposites. Site and Duration: The experiments were carried out at Jomo Kenyatta University of Agriculture and Technology for a period of two years June 2013 to June 2015. Methodology: The experiments were conducted using a completely randomized design with three replications. Deacetylation, functionalization and immobilization of chitin on mesoporous silica nanoparticles (MSN) to form chitosan immobilized silica nanocomposites (CISNC) gel was done. Results: This resulted in formation of chitosan nanoparticles and CISNC with crystallite sizes of 2.8 and 4.4 nm respectively. BCAs were adsorbed on CISNC gel. Characterization of the bio- nanocomposites showed that they had physisorption properties thus, ideal carriers for BCAs. CISNC gel had the highest significant (P=.05) sorption properties with 75% and 65% adsorption and desorption respectively of BCAs. Efficacy trials were done by in vitro pathogen inhibition and greenhouse bioassays using tomato seedlings. Adsorption of BCAs on CISNC gel significantly (P=.05) increased inhibition efficacy of BCAs on R. solanacearum from 50 to 70%. This was attributed to the antibacterial effect of the individual substances and the overall synergy acquired. Further, BCA-CISNC gel forms a film around root hairs, initiates fast wound healing mechanism and induce prophylactic effect on tomato seedlings challenged with R. solanacearum pathogen, decreasing wilting incidences from 45 to 25%. Additionally, BCA-CISNC complex significantly (P=.05) increased tomato seed germination from 70 to 80% and growth rate from 12 to 15% due to enhanced water utilization efficiency, induced phytohormones and nutritional benefit. BCAs also aided faster nutrient release, absorption and utilization by tomato plants. Conclusion: Therefore, adsorption of bacterial, fungal and phage biocontrol agents on CISNC gel, a complex hitherto not reported to have been used in R. solanacearum disease control, enhanced microbial efficacy against the pathogen and increased tomato productivity.
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    Evaluation of genetic variability and interrelationships among M3 and M4 maize inbred lines in Kenya
    (Advanced Journal of Plant Biology, 2021-02-25) Kariuki, John Kimondo; Githiri, Stephen Mwangi; Wesonga, John Mwibanda; Mallu, Tesfamichael Semere
    The present study was conducted at Jomo Kenyatta University of Agriculture and Technology, Juja to assess the agronomic performance of mutant maize lines of 39 filial generation 3 (M3) and filial generation 4 (M4) maize lines and a check variety among agro-morphological traits with their association with grain yield. Data on various agro-morphological characters were recorded using morphological descriptors for maize and analyzed using Genstat Release 14.1. Data was also subjected to XLSTAT 2014 and DARwin 6.0.12 software for principal and cluster analyses. Results obtained differed significantly in herbicide tolerance days for both M3 and M4 (p≤0.01). However, plant height, maturity days, flag leaf length and width, grains ear-1 , ear length, ear diameter and grain yield plant-1 differed significantly in M3 and M4 lines (p≤0.05). Grain yield plant-1 showed a strong significant positive correlation with anthesis days, plant height, grains ear-1 and ear diameter and length but negatively correlated with days to pollen shedding, tasseling, maturity and tolerance in M3 while flag leaf width, harvestable and total ears plant-1 showed positive and significant correlation but negatively correlated with tolerance days in M4. Principal component analysis showed variations among mutated maize lines in M3 and M4 with first seven principal components (PC) indicating that the first six PCs explained 78.69% and first six PCs contributing 71.28% respectively of the total variation. Cluster analysis showed three clusters and seven sub-clusters indicating differences in morphological diversity among the M3 inbred lines and two clusters with cluster one of hybrid 513 and three sub-clusters in cluster two of hybrid 520. Plant height, flowering days and ear length were crucial phenological traits determining grain yield among herbicide tolerant lines showing significant variability that could be considered in hybridization and development of herbicide tolerant hybrid genotypes in future maize breeding programmes.
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    Publication
    Evaluation of genetic variability and interrelationships among M3 and M4 maize inbred lines in Kenya
    (Advanced Journal of Plant Biology, 2021-02-25) Kariuki, John Kimondo; Githiri, Stephen Mwangi; Wesonga, John Mwibanda; Mallu, Tesfamichael Semere
    The present study was conducted at Jomo Kenyatta University of Agriculture and Technology, Juja to assess the agronomic performance of mutant maize lines of 39 filial generation 3 (M3) and filial generation 4 (M4) maize lines and a check variety among agro-morphological traits with their association with grain yield. Data on various agro-morphological characters were recorded using morphological descriptors for maize and analyzed using Genstat Release 14.1. Data was also subjected to XLSTAT 2014 and DARwin 6.0.12 software for principal and cluster analyses. Results obtained differed significantly in herbicide tolerance days for both M3 and M4 (p≤0.01). However, plant height, maturity days, flag leaf length and width, grains ear-1, ear length, ear diameter and grain yield plant-1 differed significantly in M3 and M4 lines (p≤0.05). Grain yield plant-1 showed a strong significant positive correlation with anthesis days, plant height, grains ear-1 and ear diameter and length but negatively correlated with days to pollen shedding, tasseling, maturity and tolerance in M3 while flag leaf width, harvestable and total ears plant-1 showed positive and significant correlation but negatively correlated with tolerance days in M4. Principal component analysis showed variations among mutated maize lines in M3 and M4 with first seven principal components (PC) indicating that the first six PCs explained 78.69% and first six PCs contributing 71.28% respectively of the total variation. Cluster analysis showed three clusters and seven sub-clusters indicating differences in morphological diversity among the M3 inbred lines and two clusters with cluster one of hybrid 513 and three sub-clusters in cluster two of hybrid 520. Plant height, flowering days and ear length were crucial phenological traits determining grain yield among herbicide tolerant lines showing significant variability that could be considered in hybridization and development of herbicide tolerant hybrid genotypes in future maize breeding programmes.