Browsing by Author "Sadik, Kassim"
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Item Dietary amino acid requirements of pebbly fish, Alestes baremoze (Joannis, 1835) based on whole body amino acid composition(Aquaculture Reports, 2019) Kasozi, Nasser; Iwe, Gerald; Sadik, Kassim; Asizua, Denis; Tibenda Namulawa, VictoriaAlestes baremoze is a valuable food fish with a wide geographical distribution in East, North and West Africa. Currently, the nutritional requirements of A. baremoze have not yet been determined, which hinders attempts towards developing appropriate feed formulations for its culture. This study was thus conducted to estimate essential amino acid (EAA) requirements of A. baremoze using the A/E ratio method, as a guide in formulating its diet. Fish samples used in the study were categorised into four classes according to their fork lengths (1–12 cm; 13–24 cm; 25–36 cm and 37–48 cm), with each class consisting of 10 fish. Results from the amino acid composition analysis revealed significant difference (P<0.05) in the concentration of tryptophan, lysine, methionine, threonine, phenylalanine, isoleucine and valine amongst the different class sizes of A. baremoze. The A/E ratios of A. baremoze muscle tissue were in the same range with those obtained from other fish species, except for tryptophan. When expressed as a percentage of dietary protein, the EAA requirements of A. baremoze, were however not significantly different (P > 0.05) within the four classes. The EAA requirement profiles for A. baremoze were found to be similar to those observed in other omnivorous fish species. Considering the importance of A. baremoze as a potential species for freshwater aquaculture, the present data provides guidance to the development of test diets with appropriate amino acid inclusions until dose response treatments are carried out.Item Estimates of combining ability and heritability in cowpea genotypes under drought stress and nonstress conditions in Uganda(Journal of Plant Breeding and Crop Science, 2017) Mwale, Saul Eric; Ochwo Ssemakula, Mildred; Sadik, Kassim; Alladassi, Boris; Rubaihayo, Patrick; Gibson, Paul; Singini, Wales; Edema, RichardCowpea is an important source of food and income for small scale farmers in Uganda. Production is, however, affected by both biotic and abiotic stresses. Drought stress has recently emerged as a serious concern due to the effects of climate change. This study was therefore undertaken to estimate the general and specific combining ability effects of parents and crosses as well as estimate the heritability of delayed leaf senescence, seed yield and its components under drought stress. Five drought tolerant genotypes were crossed with four drought sensitive genotypes in a North Carolina II mating design. The study revealed that drought tolerance is conditioned by both additive and non-additive genetic effects with the predominance of non-additive genetic effects for seed yield, 100 seed weight and number of pods per plant. Delayed leaf senescence was however, controlled by additive genetic effects, implying that progenies performance could be predicted from parents General Combining Ability (GCA) effects. The cultivars SECOW 5T, IT93K-452-1 and IT98K-205-8 were good combiners for drought tolerance. The F2 families: SECOW 3B x IT98K-205-8, SECOW 5T x IT98K-205-8, SECOW 4W x IT98K- 205-8 and SECOW 1T x IT98K-205-8 had positive Specific Combining Ability(SCA) effects in seed yield, number of pods per plant and 100 seed weight, implying that they performed better than what was predicted by their parents GCA effect. As such, they are promising cross combinations that can be advanced for later generation selection.Item Genetic Analysis of Weevil (Cosmopolites Sordidus) Resistance in an F2 Diploid Banana Population(Journal of Plant Breeding and Genetics, 2015) Arinaitwe, Ivan K.; Barekye, Alex; Kubiriba, Jerome; Sadik, Kassim; Karamura, Eldad; Edema, RichardThe East African highland bananas (Musa spp. AAA), an important staple food in Uganda, are highly susceptible to the banana weevil (Cosmopolites sordidus Germar). Sources of host plant resistance to the banana weevil exist in wild diploid bananas. The use of wild diploid bananas to improve East African highland bananas can be facilitated by studying genetics of host plant resistance of inter-diploid crosses. The objectives of this study were a) to identify segregating weevil resistance and agronomic traits in an F2 diploid population, and, b) to determine the inheritance of banana weevil resistance and agronomic traits based on an F2 banana diploid population. An F1 population developed from Musa acuminata subsp. banksii acc. Kasaska (ITC0591) and M. acuminata subsp. microcarpa acc. Borneo (ITC0253) was selfed to generate an F2 diploid population. The F2 population was screened against weevil resistance and agronomic traits in the laboratory, pot and field experiments. There were significant differences (P < 0.05) among the different genotypes for banana weevil resistance traits such as head capsule width, body length, body weight, larval mortality, total damage, peripheral damage, dead weevils and larvae retrieved. There were also significant differences (P < 0.05) for agronomic traits such as inner corm hardness and total corm hardness. The histograms for the banana weevil resistance traits such as head capsule width, body length, body weight and larval mortality, total damage, peripheral damage, cross sectional inner and outer damage, larvae retrieved and dead weevils showed continuous distribution. Similarly, histograms for agronomic parameters such as height of plant at flowering and girth at 1 meter at flowering showed continuous distribution. The Chi-square test of goodness of fit indicated that weevil growth and damage parameters had significant modifications of the expected 9:3:3:1 ratio for two independent loci, thus suggesting epistasis affects their inheritance.Item Inheritance of cowpea resistance to flower thrips in Uganda germplasm(Journal of Plant Breeding and Crop Science, 2018) Agbahoungba, Symphorien; Karungi, Jeninah; Badji, Arfang; Sadik, Kassim; Gibson, Paul; Edema, Richard; Assogbadjo, Achille E.; Rubaihayo, Patrick R.Flower thrips [Megalurothrips sjostedti (Trybom)] is the most damaging insect pest on cowpea. However, information regarding the nature of gene action governing the inheritance of resistance to thrips is not available for cowpea genotypes in Uganda. This study was carried out to determine the inheritance pattern of cowpea resistance to flower thrips. Five resistant cowpea genotypes and three susceptible genotypes were crossed in full diallel mating design. F2 progenies were evaluated along with the parents in alpha lattice design with two replications under natural thrips infestation at Kabanyolo, Arua and Serere in Uganda. Combining ability analysis was performed using method one and model one of diallel analysis. The results showed that the environmental effects were highly significant (P<0.001). Additive, dominance and epistasis effects had major contributions. The broad sense heritability varied from 18 to 42% for thrips damage scores and from 0 to 6% for thrips counts. The estimates of narrow sense heritability were low for thrips damage score (2 to 18%) and thrips counts (0 to 9%). Genotypes TVU-1471 and TVU-1509 were identified as good transmitters of resistance to flower thrips. Crosses TVU-1509 x NE5, TVU-473 x Sanzi, TVU-123 x Sanzi, TVU-123 x TVU-473, and TVU-473 x TVU-1509 presented significant (P<0.05) and negative SCA effects for thrips damage scores and thrips counts and would be the most useful in breeding as some of their progenies would have high resistance to flower thrips. This study provides the basis of an efficient breeding program of cowpea for flower thrips resistance.Item Microsatellites markers associated with resistance to flower bud thrips in a cowpea F2 population derived from genotypes TVU-123 and WC36(African Journal of Biotechnology, 2018) Agbahoungba, Symphorien; Karungi, Jeninah; Sadik, Kassim; Gibson, Paul; Edema, Richard; Assogbadjo, Achille E.; Rubaihayo, Patrick R.Breeding for resistance to flower bud thrips (Megalurothrips sjostedti) in cowpea has been hindered by the quantitative nature of resistance. To identify simple sequence repeat (SSR) markers associated with resistance to flower bud thrips that could be used for marker-assisted breeding, a F2 population was generated from a cross between genotypes TVU-123 (resistant) and WC36 (susceptible). The population was evaluated for thrips damage scores, thrips counts, and pods number per plant under artificial infestation. Sixty-six microsatellites markers were screened between the two parental lines and seven polymorphic markers were used for genotype 100 F2 plants. Single marker analysis was used to evaluate an association between the markers and traits. Transgressive segregation among the F2 plants for resistance to flower thrips was observed. A significant negative relationship was observed between thrips damage scores and pods number per plant. Markers CP37/38 and CP215/216 were significantly associated with thrips damage scores and thrips counts, respectively. The two markers explained 7 and 11.2% of the total variation in thrips damage scores and thrips counts with positive and negative effects, respectively. Mainly additive gene effects were observed. A more detailed study using more markers on these loci should provide better understanding of this complex trait.Item New sources of cowpea genotype resistance to cowpea bruchid Callosobruchus maculatus (F.) in Uganda(International Journal of Agronomy and Agricultural Research, 2018) Belay Miesho, Weldekidan; Gebremedhin, Hailay Mehari; Msiska, Ulemu Mercy; Mohammed, Khalid Elsiddig; Malinga, Geoffrey Maxwell; Sadik, Kassim; Lapaka Odong, Thomas; Rubaihayo, Patrick; Kyamanywa, SamuelCowpea bruchid Callosobruchus maculatus (F.) is a major constraint to cowpea production throughout subsaharan Africa. The identification of sources of C. maculatus resistance and their incorporation into breeding programs would be a beneficial strategy to combat the devastation caused by the bruchid in stored cowpea. We evaluated 145 cowpea genotypes from Uganda and introductions from Kenya and Nigeria for resistance to bruchids. The mean number of eggs and number of holes, percentage pest tolerance, percentage weight loss, bruchid developmental period, bruchid growth and Dobie susceptibility index were significantly different among the 145 genotypes. Based on Dobie susceptibility index value, there were 18 resistant, 114 moderately resistant and 13 susceptible genotypes. Dobie’s susceptibility index correlated negatively with insect development period and percentage pest tolerance, and positively with number of eggs, growth index, number of holes and weight loss. The study identified new sources of cowpea from the studied genotypes that could be used by cowpea breeders to develop cultivars with relatively high resistance to cowpea bruchid. However, further investigations and identifcation of biochemicals that are responsible for cowpea seed resistance to bruchid are recommended.Item Response of Cowpea Genotypes to Drought Stress in Uganda(American Journal of Plant Sciences, 2017) Mwale, Saul Eric; Ochwo-Ssemakula, Mildred; Sadik, Kassim; Achola, Esther; Okul, Valentor; Gibson, Paul; Edema, Richard; Singini, Wales; Rubaihayo, PatrickMoisture stress is a challenge to cowpea production in the drought prone areas of eastern and north eastern Uganda, with yield losses of up to 50% reported. Genotypes grown by farmers are not drought tolerant. This study was therefore, undertaken at Makerere University Agricultural Research Institute Kabanyolo to identify cowpea genotypes tolerant to drought. Thirty cowpea accessions comprising of Ugandan landraces and released varieties, Brazilian lines, Makerere University breeding lines, elite IITA germplasm and seven IITA drought tolerant lines as checks were screened for drought tolerance at vegetative and reproductive stages. The experiment was designed as a 2 × 37 factorial and laid out in a split-plot arrangement, 37 genotypes of cowpea at two soil moisture stress levels (T1, no stress and T2, severe stress) with all factorial combinations replicated two times in a screen house. The genotypes showed considerable variability in tolerance to drought. Genotypes were significantly different for chlorophyll content (P ≤ 0.01), efficiency of photosystem II (P ≤ 0.05), non-photochemical quenching (P ≤ 0.05), recovery (P ≤ 0.01), delayed leaf senescence (P ≤ 0.01), grain yield (P ≤ 0.01), 100 seed weight (P ≤ 0.05), number of pods per plant and number of seeds per pod (P ≤ 0.001). There was a highly significant positive correlation between chlorophyll content and efficiency of photosystem II (r = 0.75, P ≤ 0.001) implying that chlorophyll content and efficiency of photosystem II could be used as efficient reference indicators in the selection of drought tolerant genotypes. Genotypes SECOW 5T, SECOW 3B, SECOW 4W, WC 30 and MU 24 C gave relatively high yields under stress and no stress conditions, maintained above mean chlorophyll content, efficiency of photosystem II and had good recovery scores from stress and thus were tolerant to drought stress induced at both vegetative and reproductive stages.Item Site suitability assessment of selected bays along the Albert Nile for Cage Aquaculture in West Nile region of Uganda(International Journal of Fisheries and Aquaculture, 2016) Kasozi, Nasser; Opie, Hellen; Iwe, Gerald; Enima, Christopher; Nkambo, Mujibu; Turyashemererwa, Martin; Naluwayiro, Janet; Sadik, KassimSelection and management of sites are among the most significant elements for the success and sustainability of aquaculture operations. Water quality, water depth and water current are three of the major factors that need to be considered before initiating cage culture in a natural water body. This study was conducted to identify suitable sites for cage farming along the Albert Nile of Uganda by assessing the physical, chemical and topographical characteristics over a three month period. Four bays (Odoi, Fundo, Onere and Isirini) were randomly sampled and the results were compared against the acceptable standards. Basing on the physical and chemical criteria, most of the surveyed points were within the acceptable ranges except for the water depths which were lower and total suspended solids which were higher than the recommended ranges. Regarding topographical characteristics, Odoi and Fundo bays were found to be very prone to floating weeds and submergent macrophytes. All the sampled areas within Odoi, Fundo and Onere fishing bays whose depths were found to be more than 2 m can be manipulated to have Low Volume High Density (LVHD) cages while Isirini, Acaar and Ayilebe fishing bays were found not to be suitable for cage culture because they were very shallow.