Browsing by Author "Odong, T.L."
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Item Biochemical Constituents Influencing the Resistance to Flower Bud Thrips in Cowpea [Vigna Unguiculata (L.) Walp] Germplasm(The Journal of Animal & Plant Sciences, 2018) Agbahoungba, S.; Karungi, J.; Odong, T.L.; Badji, A.; Kumi, F.; Mwila, N.; Rubaihayo, P.R.The flower bud thrips, Megalurothrips sjostedti, is a major pest of cowpea that can cause yield losses of up to 100%. The use of cowpea cultivars resistant to thrips is among the most promising control measures. Six cultivars were evaluated in 2016 in Uganda for resistance to thrips under field conditions and analyzed for total carbon, total reducing sugar, total protein, soluble amino acid, total phenol, flavonoids, antioxidant activity and tannin contents. Data were subjected to analysis of variance, correlation and multiple linear regression analyses. The results showed that the genotypes responded differently to thrips damage and thrips counts in flowers and they presented different concentrations in total reducing sugar, total carbon, soluble amino acid, antioxidant activity, flavonoids and tannin in the plants parts. Cultivar TVU-1509 suffered the least thrips damage (1.03) while WC36 was severely damaged by thrips (6.55). A significant negative correlation was observed between thrips damage scores and total carbon concentration (r=-0.54) indicating that total carbon plays a significant role against thrips damage in cowpea. Increase in the concentration of flavonoids, total reducing sugar, total carbon in the plants contributed to the reduction of thrips damage (coefficient of regression = -1.47; -0.61 and -0.48, respectively) while the increase in the concentration of the soluble amino acid contributed to the increase of thrips damage (coefficient of regression = 2.10), suggesting that these biochemical conferred the resistance of cowpea to flower thrips damage. These biochemical compounds could be promising candidates to bolster cowpea cultivars ’resistance.Item Correlations and Path Analysis of Yield Traits in Sorghum Grown in Southwestern Highlands of Uganda(African Crop Science Journal, 2019) Akatwijuka, R.; Rubaihayo, P.R.; Odong, T.L.The study of relationships among traits is essential for assessing the feasibility of joint selection for two or more traits. Path coefficient analysis partitions correlation coefficient into direct and indirect contributions of various traits towards dependent variable, thus guiding effective selection. A study was conducted to determine the correlation and path coefficients for sorghum (Sorghum bicolor L. Moench) grain yield and quantitative traits among 47 sorghum cultivars collected from southwestern highlands of Uganda. The study was conducted at Kachwekano Research Farm in Kabale District in southwestern Uganda, at an altitude of 2,223 metres above sea level, during the two successive sorghum growing seasons of December 2014 to August 2015 and December 2015 to August 2016. Correlations revealed strong significant trait associations (P<0.001) for grain yield with panicle weight (r=0.938), and moderately strong relationships with panicle width (r=0.619), stem girth (r= 0.674), and leaf width (r=0.576). Grain yield revealed a non-significant negative correlation with days to 50% flowering (r=-0.011). Regression analysis revealed that panicle weight and plant height had the highest direct effect on grain yield of 1.085 and 0.2097, respectively. Path coefficient analysis revealed that stem girth (0.814), leaf width (0.74901) and panicle width (0.713) had the highest indirect contributions to grain yield. The residual effect was low (R=0.11), with high adjusted R2 value (0.89).Item Genetic Diversity among Sorghum Landraces of Southwestern Highlands of Uganda(African Crop Science Journal, 2016) Akatwijuka, R.; Rubaihayo, P.R.; Odong, T.L.Sorghum (Sorghum bicolor L. Moench) is an economic and staple crop in sub-Saharan Africa. The genetic diversity in its germplasm is an invaluable aid for its crop improvement. The objective of this study was to assess the existing genetic diversity among sorghum landraces in the southwestern highlands of Uganda. A total of 47 sorghum landraces, collected from southwestern highlands of Uganda, were characterised using 12 qualitative and 13 quantitative traits. The study was conducted at Kachwekano Research Farm in Kabale District, at an altitude of 2,223 m above sea level, during growing season of December 2014 to August 2015. Panicle shape and compactness were the most varied qualitative traits. Grain yield (1.23 to 11.31 t ha-1) and plant height (144.7 to 351.6 cm) were among quantitative traits that showed high variability. Days to 50% flowering (115 to 130 days) showed the least variability. Results of UPGMA cluster analysis generated a dendrogram with three clusters. Panicle weight, leaf width, stem girth, exertion length, peduncle length, panicle shape and compactness, glume colour and threshability were major traits responsible for the observed clustering (P<0.001). Principal Component Analysis revealed the largest variation contributors.Item Maize resistance to stem borers and storage pests: The need for new genetic and functional genomics approaches in future research(African Journal of Rural Development, 2017) Badji, A.; Otim, M.; Machida, L.; Odong, T.L.; Kyamanywa, S.; Rubaihayo, P.Insect pests are primary constraints in maize (Zea mays) production in many places in sub-Saharan Africa. Stem borers and storage pests are responsible for severe yield losses and health hazards due to mycotoxin contamination. Integrated pest management (IPM) strategies have moved from control methods and transgenic resistance to recognizing the necessity of host plant resistance (HPR) especially in the context of an ever changing climate and its forecasted negative consequences. For that, a wealth of scientific knowledge has been generated over the years although the goals are far to be reached. Here, we first review current literature on maize resistance mechanisms as regards to insect herbivory. We show that there are numerous insect species that feed on maize before narrowing down to stem borers and storage pests. We also look at the basis of maize resistance in terms of its biochemical components and analyze the progress of genetic studies in terms of QTL mapping and trait genes identification. Finally, we highlight the usefulness of new genetic and functional genomic approaches in underpinning the genetic basis of maize resistance to insect pests in general and particularly stem borers and storage pests.Item Revisiting Application of Statistics in Agricultural Research in Sub-Saharan Africa: Entry Points for Improvement(African Crop Science Journal, 2019) Odong, T.L.; Tenywa, J.S.; Nabasirye, M.The importance of statistics in empowering the agricultural research process and sharpening interventions cannot be over-emphasized. Undocumented evidence points to misconceptions, misuse or underuse of statistics among agricultural researchers in sub-Saharan Africa (SSA); pointing to the possibility that the subject has been part of the causes the unfulfilled targets in the agricultural sector in the region. The objective of this study was to analyse and document weaknesses in statistical practice in agricultural research, with a view to identifying entry points for strengthening the performance of the sector for SSA to be able to achieve its set goals. A desk study involving 165 research articles published in the African Crop Science Journal over the period of 17 years (2000 to 2017) was conducted through a rigorous SWOT analysis for issues related to the use of statistics in the implementation of agricultural research in SSA. A checklist consisting of key elements related to study design; data collection, analysis and exploitation; and presentation, was used to guide the interrogation. Findings indicated that researchers generally made explicit description of treatment structures that fairly matched the study objectives and hypotheses (in the few cases where they were stated), with a few weaknesses in the description of factorial treatment structure. The Randomised Complete Block Design was most commonly used among the designs, with 3-4 replicates. However, there was hardly any justification for its use, as the blocking factors were never mentioned and thus their role in determining the precision of the results was difficult to determine. Analysis of Variance was the main method for data analysis, followed by correlations. The F-test and the associated Pvalues were the basis for decisions on treatment differences. Most researchers had problems with presentation and interpretation of P-values and significance level. Post adhoc tests mostly used the Least Significant Difference (LSD) for pairwise mean comparisons, with little consideration for the treatment structure, the number of treatments and the nature (qualitative or quantitative). Generally, estimates of treatment means were presented together with various measures of precision, in both tables and graphical forms. In several cases, LSD was used or misused interchangeably with standard error (SE) or standard error of difference (SED). Several statistical software were used for data analysis and presentation, with the main ones being SAS, Genstat and MSTAT-C. Key entry points for improvement heavily lie in human and infrastructural resource capacity improvement, most specifically in (i) periodic review of university and other tertiary institutions’ curricula to provide sufficient time allocation, physical space and relevant infrastructure for true hands on practice; (ii) more effective utilization of the few statisticians available in the region, (iii) short term staff in-service retooling courses, (iv) sustained statistical service units wherever necessary, and (v) provision for periodic interactive statistician-researcher platforms (such as conferences and workshops) for sharing notes on challenges and achievements during implementation of their research programmes.