Browsing by Author "Karungi, J."
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Assessing the Effects of Water Management Regimes and Rice Residue on Growth and Yield of Rice in Uganda(American Journal of Experimental Agriculture, 2015) Awio, T.; Bua, B.; Karungi, J.This study was conducted to assess the influence of different water and rice straw management practices and rice genotypes on growth and yield of rice in Uganda. Study Design: Field experimental design was a Randomized Complete Block Design while the screen house study design was a Completely Randomized Design. Place and Duration of Study: The study was conducted in the field at National Crops Resources Research Institute (NaCRRI) Namulonge and in the screen house at Kyambogo University during the period of February-July 2013. Materials and Methods: Ten rice genotypes obtained from the cereals program at NaCRRI Namulonge were grown under different water management regimes, with and without rice straw incorporation both in the field and screen house. Water management regimes used were alternate wetting and drying (AWD), continuous flooding (CF) and continuous drying (CD). Results: A significant variation in grain yield was observed among rice genotypes and under different water management regimes (P<0.001). Use of rice straw influenced rice yield in the screen house (P<0.001) but not in the field (P=0.23); interactions of water management x genotype and water management x rice straw x genotype influenced rice yield in the field (P=0.003) but not in the screen house (P=0.5). Higher yield gain was observed under the water-saving technology alternate wetting and drying compared to continuous flooding or drying. Conclusion: This study has indicated significant variations in field performance of rice under different water management regimes and rice straw usage. These findings are therefore important because they suggest that efficient management of water resources and rice residues from rice fields coupled with the use of drought tolerant rice varieties could be an effective integrated approach to improve rice yield and an adaptation strategy to the observed climate variability.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 Efficiency and possibilities for Arabica coffee-banana management systems switching in the Mt. Elgon landscape of Uganda(African Crop Science Journal, 2020) Sebatta, C.; Mugisha, J.; Bagamba, F.; Nuppenau, E.A.; Domptail, S.E.; Ijala, A.; Karungi, J.Sustainably intensifying rural agricultural systems is now a development goal that has gained momentum in the recent decades due to a rapidly growing population and feeds directly into the Sustainable Development Goals of ending poverty and hunger. By 2050, the world will be inhabited by 10 billion people, 68% of whom will be city dwellers which will pose serious food and livelihoods security threats to millions of people, especially in Sub-Saharan Africa. The objective of this study was to analyse technical efficiency of four production systems in Arabica coffee-banana farming system of the Mt. Elgon in Uganda and assesses possibilities for switching from one system to another. The study was motivated by the notion that smallholder farmers do not easily adopt new systems because of opportunity costs related to input substitution, input and/or efficiency reduction and systems redesigning. We estimated a production function to measure technical efficiency and ordered the intensification pathways to create a Technical Efficiency (TE) gradient. An ordered logit model was then estimated to determine the factors influencing farmers to switch among systems, by adopting one or more following a TE gradient. Results showed that farmers produced 50% of the maximum possible Arabica coffee output, indicating huge gaps between actual and potential yields. Use of fertiliser for the lowest efficiency. Low-input-low-output pathway and improved coffee genotypes, manure and labour intensification for the higher technical efficiency clusters such as conventional and mild agroecological would also significantly increase the chances of switching from low to highly efficient and sustainable Arabica coffee production systems in the Mt. Elgon watershed of Uganda.Item Oviposition preference and offspring performance of Crocidolomia pavonana (Lepidoptera: Pyralidae) on different host plants(Journal of Applied Entomology, 2010) Karungi, J.; Lubanga, U. K.; Kyamanywa, S.; Ekbom, B.The cabbage head caterpillar Crocidolomia pavonana (Fabricius) (Lepidoptera: Pyralidae) is an increasingly devastating pest on white cabbage (Brassica oleracea var. capitata) in Uganda. Screen house and field trials were used to assess oviposition preference and offspring performance of C. pavonana on six hosts in the genus Brassica: kale (B. oleracea var. acephala), cauliflower (B. oleracea var. botrytis), broccoli (B. oleracea var. italica), Chinese cabbage (B. campestris spp. pekinensis), Indian mustard (B. juncea (L.) Czern.) and white cabbage (B. oleracea var. capitata). To assess oviposition preference, the hosts were offered to C. pavonana in multiple-choice (all six); two-choice (cabbage with each of the other hosts) or cabbage-only situations. After specified oviposition periods, egg numbers on individual plants were recorded. To determine C. pavonana offspring performance on the six hosts, whole plants were placed in individual cages, where larvae were monitored for development time, pupal weight and foliage consumption. Results of the choice tests indicated that C. pavonana preferred Chinese cabbage and broccoli for oviposition. In two-choice arrangements, all the tested host plants were able to greatly reduce oviposition on white cabbage (69–100%) when compared with the monocrop. Chinese cabbage was the most suitable host with regard to C. pavonana offspring performance as demonstrated by the shortest development time and highest pupal weight. Chinese cabbage and broccoli can be used as traps for the pest but the resulting larvae should be destroyed regularly to prevent accumulation in the system.Item Relating shading levels and distance from natural vegetation with hemipteran pests and predators occurrence on coffee(Journal of applied entomology, 2015) Karungi, J.; Nambi, N.; Ijala, A. R.; Jonsson, M.; Kyamanywa, S.; Ekbom, B.The study was carried out to determine the effect of shading levels and/ or distance from the natural alpine vegetation (NAV) on the occurrence of two insect functional groups: hemipteran herbivores and generalist predators in farmers’ coffee fields in the Mt. Elgon region of Uganda. Three distance categories from the NAV, that is (i) 0–250 m; (ii) 250– 1000 m and (iii) 1000–1500 m, were used to demarcate farms in the first stage of selection, and within each distance category, three levels of shading, that is (i) no shade, (ii) moderate shade and (iii) full shade, were used for final selection of coffee farms for the study. A total of 90 individually owned coffee fields were studied; 30 for each distance category, of which 10 represented each shading level. In two separate rounds, inventories of scale insects (Coccus spp.), antestia bugs (Antestiopsis spp.), root mealybugs (Planococcus spp.) and aphids (Toxoptera aurantii) on coffee plants were made for the hemipteran herbivores, whereas ants (Formicidae) and spiders (Araneae) were recorded for the predatory taxa. The results showed that the interaction between distance from the NAV and shading level consistently influenced the occurrence of the insects in both functional groups. For scale insects, root mealybugs and ants, it was closest to the NAV that shading-level effects were most discernible and generally limiting. To the contrary, the occurrence of aphids and spiders increased with the increase in the level of shading for plants furthest from the NAV. These results indicate that if inclusion of shade trees is to be a strategy in ecological pest management, the level of shading should be determined basing on the insect taxa as well as other pertinent factors in the landscape.