Uganda Journal of Agricultural Science (UJAS)
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Contribution of granule bound starch synthase in kernel modification of quality protein maize
Get PDFThe role of gbssI and gbssII genes, encoding granule bound starch synthase enzyme I and II, respectively, in quality protein maize (QPM) were studied at different days after pollination (DAP). Total RNA was used for first strand cDNA synthesis using the ImpromIISriptTM reverse transcriptase. No detectable levels of gbssI were observed. The results showed a gradual increase in expression of gbssII from 6 to 30 DAPS and gbss expression was higher in non-QPM than QPM material. Modification level 1 and 2 had lower expression levels than level 4. In general, grain endosperm opaqueness modification is rated on a scale of 1(completely hard / vitreous) to 5 (soft opaque). Overall, this study showed that gbss activity, based on its isoform gbssII was high at 30 DAP when maximum accumulation of amylose occurs. It was generally compromised in QPM than in non-QPM materials and appeared to be influenced by opaque donor parent. Protein analysis revealed a mar ked increase of GBSS in both QPM and non QPM. There was a higher proportion of GBSSII than I extracted from developing endosperm in both QPM and non QPM. At 18 DAP, the amounts of extractable GBSSII and I were lower in modified maize line 4 comparable to amounts in level 1 modified germplasm. In contrast, at 30 DAP; the GBSSII and I protein quantities at level 2 were lower than level 4, but comparable to level 3. The major finding was that transcript use was unreliable because the genes under study (gbssI and II) were influenced by other non-allelic interactions. The stability of both GBSS and zein proteins coupled with the use of SDS-PAGE implied that only one was more reliable and required further validation. It was clear from this study, that kernel modification was regulated by complex genetic interactions. Fairly distinct systems such as the starch synthases, zein proteins and perhaps other non-allelic genetic systems all appeared to act in a complementary manner to regulate kernel texture
Effects of financing mechanisms in enhancing commercialization: The case of banana marketing in Kenya
Get PDFThe initiative to promote tissue cultured banana in Kenya was taken up by several Research and Development (R&D) agencies in the last two decades with an aim of improving the income and welfare of smallholder resource-poor farmers in the region. Most interventions focused on improving production and producers’ incomes. While farmers have intensified production and are marketing their produce, little efforts have focused on development of local markets, which are vital in spurring commercialization. Inadequate financing has been constantly cited as a major factor constraining agribusiness ventures. A study was conducted to assess financing mechanisms and their effects on banana businesses within the period March – April 2012. A total of 205 banana traders were randomly sampled from banana markets in Kirinyaga, Meru, Kisii and Nairobi Counties. A semi-structured questionnaire was used to collect data from the sampled traders. Descriptive statistics were used to characterize banana traders and enterprises. The study revealed that the majority of traders (82.4%) financed banana business activities through their savings while 17.6% accessed credit. However, the commercial level of operation of those who accessed credit was significantly higher than that of those who used their own savings. Thus, credit is important in supporting expansion of banana businesses and mobilizing banana trader associations for savings and credit access by members is likely to complement commercialization efforts
Use of Ca-bentonite to ameliorate moisture and nutrient limitations of sandy soils in drought stricken areas
Get PDFMoisture shortage is a major factor limiting crop production in sandy soils. This study evaluated the potential for Ca-bentonite (2:1 clay mineral) as an amendment for increased moisture retention by sandy soils in drought stricken/prone areas. In the green house, maize was grown to sandy soil containing 0, 5, 10, 15 and 20% Ca-bentoniteby weight, replicated three times. The mixtures were watered to field capacity (30% water) then maize (Longe V) grown for 5 weeks without additional water. In the field, Ca-bentonite was applied on sandy soils in the drought-prone Lwabiyata sub- county, Nakasongola district, Central Uganda. Treatments included: Ca-bentonite at 0, 1.25 and 2.5 t ha-1; DAP at 0, 62.5 and 125 kg ha-1; urea at 0 and 60 kg ha-1; and farmyard manure (FYM) at 0, 1.25 and 2.5 t ha-1, arranged in arandomized block design with three replicates. Under greenhouse conditions, Ca-bentonite significantly (P<0.05) increased soil moisture retention, pH, N, P, Ca and Mg content, and subsequently, maize dry matter yield. Under field conditions, Ca- bentonitesignificantly (P<0.05) increased maize grain yield by 40%. Yields were even higher (65 to 108% above the control) where bentonite was combined with FYM and/or DAP. Results suggest that Ca-bentonite has potential asa soil amendmentfor moisture conservation, neutralizing acidity, and improving N, P, Ca and Mg contentin sandy soils, and consequently support crop growth and yield, and therefore presents a possible option for amelioration of sandy soils in drought stressed environments, hence climate change adaptation
Integrated nutrient management for orange-fleshed sweet potato in south eastern Nigeria
Get PDFIn the rainforest of south eastern Nigeria, new varieties of orange-fleshed sweet potatoes (Ipomea batatas Lam) have been introduced but appropriate soil nutrient management for these cultivars is lacking. The present study evaluated the response of two varieties of orange-fleshed sweet potatoes (Umuspo 1 and Umuspo 3) to different fertilizer combinations (Poultry manure, NPK and agrolyser). The experiment was a split plot laid out in a randomised complete block design with three replications. Results obtained showed that weed dry matter was lower with the control or with application of 2.5t/ha poultry manure + 200kg NPK than with application of poultry manure at 10t/ha. Storage root yields obtained from 400kg/ha NPK(the check) or 2.5t/ha poultry manure + 200kg NPK were comparable but significantly higher than the yields from the control or agrolyser or from 200kg/ha NPK + agrolyser. Umuspo 1 variety gave higher shoot biomass and lower weed density than Umuspo 3. There was no interaction between the fertilizer combinations and variety, suggesting that the orange-fleshed sweet potato varieties responded similarly to nutrient management strategies
Ecological factors influencing incidence and severity of Coffee Leaf Rust and Coffee Berry Disease in major Arabica coffee growing districts of Uganda
Get PDFCoffee Leaf Rust and Coffee Berry Disease are the most devastating diseases of Arabica coffee in Africa. The importance of coffee in economies of many African countries like Uganda, presents urgent need for cost-effective disease control strategies. In this study, 192 coffee farms were surveyed and their corresponding incidence and severity recorded. Nebbi district had the highest CLR incidence (90.2%) and severity (2.2%) followed by Sironko (67.9% and 1.9%) and least in Kapchorwa (20.4% and 1.3%) respectively. CBD incidence was highest in Kapchorwa (6.0%) followed by Nebbi (1.7%).There was no CBD incidence observed in Sironko. There was a significant (pd”0.05) interaction between altitude and disease severity. Thin and medium shade intensity had highest CLR incidence followed by thick and no-shade levels. CLR was highest in farms under mono-shade followed by farms under mixed-shade and least in open-farms. CLR severity was found to be highest at very steep slopes and medium slopes and least on gentle slopes. In conclusion, CLR was present in all surveyed districts while CBDoccurred in Kapchorwa and Nebbi districts at intensity levels enough to trigger economic losses
Influence of shade systems on spatial distribution and infestation of the Black Coffee Twig Borer on coffee in Uganda
Get PDFStudies were conducted to determine spatial distribution and effects of shade systems on Xylosandrus compactus infestation on coffee. Number of twigs varied significantly (p<.0001) within canopy portions with the highest (17.7±6.1) in upper and least (9.1±4.6) in lower portions. Percentage of infested twigs and number of X. compactus entry holes varied significantly (P<.0001) within canopy and along twigs respectively. The highest percentage of infested twigs (10.7±15.9%) was in the middle whereas, the lowest (3.2±7.2%) in upper portion. The highest number of entry holes (0.9±0.7) was on basal and the lowest (0.3±0.6) on tip section of twigs. Tunneling by X. compactus was neither inclined towards base nor the tips of twigs. Percentage canopy cover varied significantly (P=0.0276) across shade tree species; with highest (60.0±26.5%) on jackfruit tree and the lowest (11.7±7.6%) on Chinese silk tree. Percentage of infested trees and twigs varied but not significantly (P<0.05) across shade categories and tree species. Coffee under full shade had the highest percentage of infested trees (70.8±27.8%) and twigs (14.8±18.3%); whereas, coffee under full sun registered the lowest (45.8±17.3 and 5.7±9.1% respectively). However, ANCOVA showed that shade and percentage canopy cover of Albizia, jackfruit and mango tree species had a significant (at P<0.05) positive influence on X. compactus infestation. The highest percentage of infested trees (77.8%) and twigs (15.7%) were observed on coffee under Ficus natalensis; whereas coffee under Maesopsis eminii had the lowest (44.4% and 1.5% respectively). These studies provided vital preliminary ecological information for designing and implementing appropriate management strategies for X. compactus
Musa balbisiana resists Xanthomonas wilt disease through interfering with the multiplication of Xanthomonas vasicola pv musacearum coupled with whole organ (leaf) death
Get PDFXanthomonas wilt disease caused by Xanthomonas vasicola pv. musacearum (Xvm) is the most devastating disease of bananas, plantains and Enset in East and Central Africa. There is no known resistant banana to this disease among the cultivated varieties but here we confirm that one wild type, Musa balbisiana is resistant. Plants recovered from wilt symptoms and although it initially migrated beyond the point of inoculation, Xvm population did not build up and its presence was restricted to the inoculated and the immediate follower leaves which subsiquently wilted and died in some plants. The pathogen population within plant tissues was observed to drop in a 50 mg tissue from 3.06x107cfu at 18days after inoculation in the inoculated leaf to 1.5x104cfu by the 12th week after inoculation in the immediate follower leaf and later to 0 cfu by the 20th week after inoculation in other follower leaves. In contrust to the same size of tissue in the susceptible cv “Nakinyika” its population increased from 3.41x108 to 1.08x1011cfu within 3 weeks after inoculation. In addition, bacterial migration within M. balbisiana was slow, where it took up to 12 weeks to be detected as far as only the immediate follower leaves. In the susceptible cv “Nakinyika” Xvm migration was faster and it had spread to adjacent leaves within 2 weeks after inoculation. Consistent with the decreasing bacterial population and limited migration, initial symptom development was also delayed, only first observed in the inoculated leaf at 10 weeks after inoculation. In addition, the incidence and severity of wilt remained low at 33% and 20% respectively and with the exception of the individual wilted leaves that subsiquently died, the plants were never broken down but continued to grow without anymore symptoms
The effect of artisanal preservation methods on nutritional security of “Mukene” Rastrineobola argentea caught from Lakes Victoria and Kyoga in Uganda
Get PDFThe artisanal fish preservation methods in Uganda are characterized by extreme operating conditions. Consequently, vital nutritional components diminish in value and quantity which renders fish consumer nutritionally insecure. To establish the magnitude of nutritional loss, duplicate samples of Mukene Rastrineobola argentea were collected from Kiyindi landing site on L. Victoria and Moone landing site on L. Kyoga. Each set of duplicate samples was divided into five portions and kept on ice. For each preservation method a portion was processed into respective products at Food Bioscience and Agri-Business Laboratories aside from the control (fresh) sample. Both preserved and control samples were analysed for nutrient loss at Department of Chemistry, Makerere University using AOAC methods. The composition of fatty acids was determined by methanolysis gas chromatography and Mass spectrophotometry of the resultant methyl esters. The results indicate that nutrients of all preserved samples did not vary significantly from the control except for some fatty acids. The Eicosapentaenoic acid (EPA) in fresh samples declined from 6.72% to 1.08% in deep-fried samples constituting 83.93% nutrient loss. The sum ratio ω3:ω6 as well as EPA: DHA (Docosahexaenoic) ratio in fried samples also varied significantly (p<0.5) lower than 0.668 and 0.20 for the average of either preservation methods and experts recommended ratio respectively. Further research has been recommended to ascertain the causative factor, since Mukene frying is being promoted in the Great lakes region as alternative method to sun-drying. In conclusion, regular consumers of fried Mukene do not benefit much from the nutritional and health attributes of Omega 3 and 6
Effect of grain splitting on biology and development of Callosobruchus Maculatus (Coleoptera: Bruchidae) in storage
Get PDFBruchids belonging to Callosobruchus spp. Order Coleoptera are the main storage loss causative pests on cowpea grains in East Africa. Losses have been estimated to be as high as 5-15 % within a few months of storage at farmers’ level. In this study the effect of grain splitting on the biology of C. maculatus was investigated. The cowpea grain treatments compared included split grains + no testa, split grains with testa, compared with whole un-split cowpea grains. Gravid female 4-day old C. maculatus were allowed to oviposit on the cowpea grain which had been pre-conditioned to 12% moisture content, then removed. Data on oviposition, adult eclosion and weights of emergent adults were collected over 3 weevil development generations. Mean separations were done using Analysis of Variance. There was significant reduction (P< 0.05) in oviposition and emergent adults for C. maculatus at F1, F2 and F3 generations on spilt compared to whole grains. Mean oviposition levels on split grain without testa was with only 1.3 ± 1 eggs compared to 258 ± 14 eggs in the controls at F3. Oviposition levels reduced with generation time in all the treatments. The control had the highest adult weevil emergence and mean adult weevil weights (78.8 ± 6.9) with no emergent adults from completely split grains at F3. Mean weevils were highest in the controls and reduced with generation time with least adult weights from the split grain. In this study we conclude that grain splitting reduces development of C. maculatus spp. and could be a viable option in the integrated management of this bruchid pest during storage at farmer level
The changing spread dynamics of banana Xanthomonas wilt (BXW) in Uganda
Get PDFBanana Xanthomonas wilt still remains a serious threat to banana production in Uganda. Although the desired long term control strategy would have been use of resistance, no sources of resistance have been found. Further the transgenic resistance under development will only be deployed in the long run. In the meantime, cultural control, remains the driver of BXW management strategy in Uganda. This requires continuous effort by the farmers and other stakeholders. It is imperative that disease spread information be continuously updated to sustainably control BXW. The study was conducted to update the status of BXWto inform the continuous refinement of the control strategy of BXW control in across all the epidemics zones in Uganda. BXW incidence increased from about 1% between 2005 and 2006 to about 3.8% in 2010 in the threatened areas. The BXW prevalence increased from below 5 to 34.4% in the same period. Meanwhile, the incidence and prevalence of BXW in the endemic areas reduced to below 10% and about 40%, respectively, from over 50% between 2006 and 2010. The high prevalence of BXW indicates that BXW is widely spread but the low incidence shows that BXW is at initial linear phases of disease epidemic across all zones. There are also a few clusters of infection with infected fields at various phases of the disease progress curve. This suggests that it is no longer feasible to classify Uganda’s banana growing areas in different epidemic zones. Consequently the strategies to control BXW across the zone are similar