Articles

Permanent URI for this communityhttp://104.225.218.216/handle/123456789/2

This community has research articles in all commodities under NARO mandate in broad areas of crops, forestry, livestock, fisheries, agro -machinery, Natural resources and Socio-economics.

Browse

Now showing 1 - 20 of 220

Golden Bananas In The Field: Elevated Fruit Pro-Vitamin A From The Expression Of A Single Banana Transgene
(Plant Biotechnology Journal, 1016-12-15) Jean-Yves Paul; Harjeet Khanna; Jennifer Kleidon; Phuong Hoang; Jason Geijskes; Jeff Daniells; Ella Zaplin; Yvonne Rosenberg; Anthony James; Bulukani Mlalazi; Pradeep Deo; Geofrey Arinaitwe; Priver Namanya; Douglas Becker; James Tindamanyire; Wilberforce Tushemereirwe; Robert Harding; James Dale
Vitamin A deficiency remains one of the world’s major public health problems despite food fortification and supplements strategies. Biofortification of staple crops with enhanced levels of pro-vitamin A (PVA) offers a sustainable alternative strategy to both food fortification and supplementation. As a proof of concept, PVA-biofortified transgenic Cavendish bananas were generated and field trialed in Australia with the aim of achieving a target level of 20 lg/g of dry weight (dw) b-carotene equivalent (b-CE) in the fruit. Expression of a Fe’i banana-derived phytoene synthase 2a (MtPsy2a) gene resulted in the generation of lines with PVA levels exceeding the target level with one line reaching 55 lg/g dw b-CE. Expression of the maize phytoene synthase 1 (ZmPsy1) gene, used to develop ‘Golden Rice 2’, also resulted in increased fruit PVA levels although many lines displayed undesirable phenotypes. Constitutive expression of either transgene with the maize polyubiquitin promoter increased PVA accumulation from the earliest stage of fruit development. In contrast, PVA accumulation was restricted to the late stages of fruit development when either the banana 1-aminocyclopropane-1-carboxylate oxidase or the expansin 1 promoters were used to drive the same transgenes. Wild-type plants with the longest fruit development time had also the highest fruit PVA concentrations. The results from this study suggest that early activation of the rate-limiting enzyme in the carotenoid biosynthetic pathway and extended fruit maturation time are essential factors to achieve optimal PVA concentrations in banana fruit.
A decline in Fish catches and the size of Oreochromis niloticus in Lake Wamala (Uganda) following human exploitation
(Afr. J. Trop. Hydrobiol. Fish., 1995-04-07) JOHN OBBO OKARONON
The fishery of Lake Wamala has declined since the lake was stocked in 1956 and opened to fishing during the 1960s. Surveys were conducted on the lake during 1975/78 and 1988/92 to investigate the causes of declining fish catches. The lake produced an average of 4000 - 6000 tonnes of fish annually from 1960s through 1970s. Total fish catches decreased from a maximum of 7100 tonnes in 1967 to less than 500 tonnes by 1990s. Catch rates decreased from about 8 kg in the I960s to less than 1 kg per net per night by 1975. During the 1970s the catch was dominated by Oreochromis niloticus (67%) followed by Clarias gariepinus (17%), and Protopterus aethiopicus (15.1 %). By 1990s the proportion of O. niloti- cus had decreased to 45.1 % while that of P. aethiopicus had increased to 37.6%. These changes seem to have been caused by overfishing resulting from increased fishing effort from the recommended 250 to about 1000 boats and the additional increase in effort through driving fish into the nets by beating water. The maximum size of O. niloticus in the fishery decreased from 32 cm total length in 1975/78 to 22 cm in 1988/92 while the size at first maturity decreased from about 21 cm to 14 cm during the period. This has been concurrent with a shift in the mesh size of gillnet used from 127 mm (5") in 1960s to 64 mm by 1990s. Environmental changes, especially in lake level in 1980, may also have affected the fishery.
Interaction of Ht and Partial Resistance to Exserohilum turcicum in Maize
(Plant Disease, 1997-03-11) P. E. Lipps; R. C. Pratt; J. J. Hakiza
Components of northern leaf blight resistance in maize due to race-specific resistance controlled by the Ht gene, partial resistance derived from inbred H99, and a combination of the two kinds of resistance, were studied subsequent to inoculation with Exserohilum turcicum race O. Lesion types, number of lesions (lesion number), percent leaf area affected (severity), and area under the disease progress curve (AUDPC) based on lesion number and severity were assessed in field studies conducted at two locations in Uganda and one location in Ohio in 1993. Lesion types observed were consistent for genotypes across locations. In general, significant differences among genotypes for data based on lesion number and severity were consistent for AUDPC based on lesion number and severity, respectively, at all locations. In Ohio, both Ht and partial resistance were effective in limiting disease development. In Uganda, susceptible inbreds (A619, A635, and B73) generally had higher severity than genotypes with partial resistance (H99, Mo17, and Babungo 3). However, there was a difference in response among genotypes depending on disease intensity at each location. Ht resistance and moderate partial resistance did not greatly affect lesion number at the higher disease intensity location, compared with the susceptible inbreds, but at the lower disease intensity location genotypes with partial resistance had fewer lesions than susceptible inbreds or the Ht conversions of the susceptible inbreds. At both plot locations, genotypes with partial resistance had lower severity than the susceptible inbreds or Ht conversions of the susceptible inbreds. Hybrids derived from crossing H99 with genotypes with moderate levels of partial resistance (Mo17 and Babungo 3) did not have significantly lower lesion numbers than hybrids of susceptible inbreds crossed with H99, but se- verity was significantly lower on these hybrids at the high disease intensity location. Results indicate that the level of partial resistance in H99 would be as effective in controlling northern leaf blight as using Ht resistance, or a combination of Ht resistance and moderate levels of partial resistance as found in Mo17.
Seed Production Aspects of Macroptilium atropurpureum cv. Siratro in Uganda
(JOURNAl OF APPLIED SEED PRODUCTION, 1997-04-09) P. Lusembo; C. Ebong; E.N. Sabiiti; J.S. Mugerwa
The effect of support height on seed yield components and seed quality of Macroptifium atropurpureum cv. Siratro was determined. Plants were sown at a spacing of 1 m x 1 m in a complete randomised block design replicated four times and staked at 0, 1, 2 and 3 metres high. Support significantly increased the number of inflorescences per plant (P<0.01), flowers per inflorescence (P<0.01), pods per seed head (P<0.01), seeds per pod (P<0.05), weight of 100 seeds (P<0.05), and seed yield per square metre (P<0.01). The number of inflorescences per plant and seed yield (g m') were highly correlated with support height, N=0.98 and 0.97, respectively. Staking significantly (P<0.05) improved the germination rate and percentage of the harvested seed.
Effect of cowpea monocultures and polycultures with sorghum and greengram on predatory arthropods
(Association of Applied Biologists, 1999-10-06) P NAMPALA; E ADIPALA; M W OGENGA -LATIGO; S KYAMANYWA; J E OBUO
Prior to implementing biological control, knowledge on availability of the possible enemies of pest(s) is important. Therefore, as part of a larger on-farm study whose main objective was to develop a farmer- friendly package for the management of cowpea pests, the diversity and abundance of insect predators within cowpea cropping systems (sole crops and intercrops) were monitored at three diverse locations in eastern Uganda. Coccinellids, syrphid larvae, spiders, Orius sp. and earwigs were observed at all locations. Abundance of Coccinellids and syrphid larvae were not influenced by the cowpea genotype nor cropping systems. Contrastingly,the abundance of predatory Orius sp., spiders and earwigs differed significantly among the cowpea cropping systems, being more common in the cowpea pure stands and cowpea + greengram than in the cowpea + sorghum intercrops.
Effect of mother plant applied nitrogen and potassium on the sowing value of true potato seed
(Uganda Journal of Agricultural Sciences, 2000-10-08) Kanzikwera , C.R.; Tenywa ,J.S; Osiru, D.S.0; Adipala, E; Bhagsari, A.S
A screen house experiment was conducted during 1996 short rains to assess carry-over effects of mother plant-applied nitrogen and potassium on seedling emergence, seedling vigour and dry matter accumulation of Solanum potato seedlings from true potato seed (TPS). Hybrid TPS was obtained from a cross between CIP 381379 (Kisoro) and Rutuku. Kisoro mother plants received N rates of 0, 120 and 240 kg ha·1, and potassium rates of 0, 132.8 and 265.6 kg ha·t. Performance of seed lots from the different fertiliser treatment combinations was compared to that of imported hybrid progenies, lP 88001, IP 88006 and KP 90178,8 obtained from mother plants supplied with 500 kg DAPha·1• Motherplantssuppliedwith120and J32.8kgNandK,respectively,producedtrueseedwithhighseedling emergence and vigour (sowing value), comparable to that of imported hybrid TPS.
Effect of Injectable Moxidectin Treatment of Cattle on Prevalence and Strongyle Egg Output under Communal Grazing Management in Uganda
(pathologie parasitaire communication, 2002-05-11) J.W. Magona; G. Musisi
The effect of moxidectin on the prevalence of nematode infection in cattle, fecal egg output and pasture contamination of common pastures was assessed in Tororo district, Uganda. In the first experiment, a treated and an untreated group of 40 head of cattle each were monitored for a period of 12 weeks, while in the second experiment a treated and an untreated group of 30 head of cattle each were monitored for seven months. In the first experiment, the prevalence of nematode infections and mean fecal egg count (FEC) of the treated group remained significantly (P < 0.05) lower than that of the untreated group from day 7 to 84. In the second experiment, strategic treatments initially led to 100% reduction of FEC in the treated cattle as compared to 82% in the untreated one. Thereafter, mean FEC in the treated cattle remained below 60 for six months, while that in the untreated cattle fluctuated between 63 and 400, depending on the amount of rainfall. In addition, contamination with infective larvae on pasture of the treated cattle was significantly (P < 0.05) lower than that of the untreated group during the wet season. Infestation with Haemonchus spp., Bunostomum spp., Oesophagostomum spp. and Trichostrongylus spp. was three-, five-, four- and two-fold lower, respectively, on pasture in treated than in untreated cattle. Moxidectin could be used in strategic parasite control under communal grazing management in tropical Africa by selective treatment of the most affected cattle age-groups during the middle and end of the wet season to reduce the level of pasture contamination.
USE OF IPM IN THE CONTROL OF MULTIPLE DISEASES IN MAIZE: STRATEGIES FOR SELECTION OF HOST RESISTANCE
(African Crop Science, 2003-08-03) R. PRATT; S. GORDON; P. LIPPS; G. ASEA; G. BIGIRWA; K. PIXLEY
Maize (Zea mays) production in sub-Saharan Africa is constantly threatened by the potential outbreak of multiple foliar diseases such as maize streak, northern leaf blight, gray leaf spot, and rust. Improvement of host resistance to these diseases can provide an important component of integrated pest management (IPM). In this paper, conventional and molecular marker-assisted breeding approaches are reviewed and strategies for improvement of host resistance are presented. Pyramiding of quantitative resistance factors using molecular breeding techniques will be facilitated through cooperative research efforts and adoption of appropriate experimental designs.
Mechanisms of Arsenical and Diamidine Uptake and Resistance in Trypanosoma brucei
(EUKARYOTIC CELL, 2003-10-04) Enock Matovu; Mhairi L. Stewart; Federico Geiser; Reto Brun; Pascal M ̈aser; Lynsey J. M. Wallace; Richard J. Burchmore; John C. K. Enyaru; Michael P. Barrett; Ronald Kaminsky; Thomas Seebeck; Harry P. de Koning
Sleeping sickness, caused by Trypanosoma brucei spp., has become resurgent in sub-Saharan Africa. Moreover, there is an alarming increase in treatment failures with melarsoprol, the principal agent used against late-stage sleeping sickness. In T. brucei, the uptake of melarsoprol as well as diamidines is thought to be mediated by the P2 aminopurine transporter, and loss of P2 function has been implicated in resistance to these agents. The trypanosomal gene TbAT1 has been found to encode a P2-type transporter when expressed in yeast. Here we investigate the role of TbAT1 in drug uptake and drug resistance in T. brucei by genetic knockout of TbAT1. Tbat1-null trypanosomes were deficient in P2-type adenosine transport and lacked adenosine-sensitive transport of pentamidine and melaminophenyl arsenicals. However, the null mutants were only slightly resistant to melaminophenyl arsenicals and pentamidine, while resistance to other diamidines such as diminazene was more pronounced. Nevertheless, the reduction in drug sensitivity might be of clinical significance, since mice infected with tbat1-null trypanosomes could not be cured with 2 mg of melarsoprol/kg of body weight for four consecutive days, whereas mice infected with the parental line were all cured by using this protocol. Two additional pentamidine transporters, HAPT1 and LAPT1, were still present in the null mutant, and evidence is presented that HAPT1 may be responsible for the residual uptake of melaminophenyl arsenicals. High-level arsenical resistance therefore appears to involve the loss of more than one transporter.
Inhibition of Agrobacterium-Induced Cell Death by Antiapoptotic Gene Expression Leads to Very High Transformation Efficiency of Banana
(Molecular Plant-Microbe Interactions, 2007-06-05)
The death of plant cells in culture following exposure to Agrobacterium tumefaciens remains a major obstacle in developing Agrobacterium-mediated transformation into a highly efficient genotype-independent technology. Here, we present evidence that A. tumefaciens exposure induces cell death in banana cell suspensions. More than 90% of embryogenic banana cells died after exposure to A. tumefaciens and cell death was accompanied by a subset of features associated with apoptosis in mammalian cells, including DNA laddering, fragmentation, and formation of apoptotic- like bodies. Importantly, these cellular responses were inhibited in cells expressing the animal antiapoptosis genes Bcl-xL, Bcl-2 3′ untranslated region, and CED-9. Inhibition of cell death resulted in up to 90% of cell clumps trans- formed with Bcl-xL, a 100-fold enhancement over vector controls, approaching the transformation and regeneration of every “transformable” cell. Similar results using sugar- cane, a crop plant known for recalcitrance to Agrobacterium transformation, suggest that antiapoptosis genes may inhibit these phenomena and increase the transformation frequency of many recalcitrant plant species, including the major monocot cereal crop plants. Evidence of inhibition of plant cell death by cross-kingdom antiapoptotic genes also contributes to the growing evidence that genes for control of programmed cell death are conserved across wide evolutionary distances, even though these mechanisms are not well understood in plants.
Inhibition of Agrobacterium-Induced Cell Death by Antiapoptotic Gene Expression Leads to Very High Transformation Efficiency of Banana
(Molecular Plant-Microbe Interactions, 2007-06-09) Harjeet K. Khanna; Jean-Yves Paul; Robert M. Harding; Martin B. Dickman; James L. Dale
The death of plant cells in culture following exposure to Agrobacterium tumefaciens remains a major obstacle in de- veloping Agrobacterium-mediated transformation into a highly efficient genotype-independent technology. Here, we present evidence that A. tumefaciens exposure induces cell death in banana cell suspensions. More than 90% of em- bryogenic banana cells died after exposure to A. tumefaciens and cell death was accompanied by a subset of features associated with apoptosis in mammalian cells, including DNA laddering, fragmentation, and formation of apoptotic- like bodies. Importantly, these cellular responses were inhibited in cells expressing the animal antiapoptosis genes Bcl-xL, Bcl-2 3′ untranslated region, and CED-9. Inhibition of cell death resulted in up to 90% of cell clumps trans- formed with Bcl-xL, a 100-fold enhancement over vector controls, approaching the transformation and regeneration of every “transformable” cell. Similar results using sugar- cane, a crop plant known for recalcitrance to Agrobacterium transformation, suggest that antiapoptosis genes may inhibit these phenomena and increase the transformation frequency of many recalcitrant plant species, including the major monocot cereal crop plants. Evidence of inhibition of plant cell death by cross-kingdom antiapoptotic genes also contributes to the growing evidence that genes for con- trol of programmed cell death are conserved across wide evolutionary distances, even though these mechanisms are not well understood in plants.
Community mobilization: A key to effective control of banana xanthomonas wilt
(Journal of Development and Agricultural Economics, 2012-03-08) Kubiriba J.; Karamura E. B.; Jogo, W.; Tushemereirwe W. K.; Tinzaara W.
Banana xanthomonas wilt (BXW) remains a major threat to banana, an important food and income crop for 12 million poor small-holder farmers in Uganda. Although, BXW has been controlled to some extent in parts of South-western Uganda, it is still a big problem in banana growing areas of Central and Eastern Uganda. We hypothesized that differential success in BXW control is mainly due to approaches used in the BXW control. This paper therefore, evaluates stakeholder mobilization approaches used in promoting technologies for BXW control in Uganda between 2006 and 2009. Results showed that farmer field schools host communities had more farmers (33%) that had low or no BXW infection (<10 infected plants) as compared to smaller proportions (23.5%) of farmers from communities that were using community action or that were mobilised using the traditional approach (22.9%) to control BXW. There was higher BXW prevalence in communities that were using community action (68.8%) or were mobilised traditionally (66.3%) than in those that hosted farmer field schools (43.4%). Consequently, there was higher (53%) banana production recovery on farms that hosted farmer field schools than those that used other institutional approaches (22%). BXW was better controlled by farmers mobilised using farmers field schools than those mobilized through community or traditional approaches.
The Changing Spread Dynamics Of Banana Xanthomonas Wilt (Bxw) In Uganda
(Uganda Journal of Agricultural Sciences, 2012-04-14) J. Kubiriba; F. Bagamba; E. Rockfeller; W.K. Tushemereirwe
Banana 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 BXW to 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.
Field spread of banana streak virus (BSV)
(Afr. J. Agric. Res., 2012-07-11) Kubiriba, J.; Tushemereirwe, W. K.; Kenyon, L.; Chancellor, T. C. B.
Musa (banana and plantain) provides a major source of carbohydrates for about 400 million people of whom 20 million are from East Africa. Yet, banana is threatened by number constraints, banana streak virus inclusive. Banana streak virus (BSV) was monitored in Rakai and Ntungamo, Uganda for up to 72 months after planting (MAP) and 29MAP respectively. BSV incidence increase over time was fitted into exponential model and spatial spread analysed by 2DCLASS and 2DCORR. BSV infection was initiated in Rakai 29 months after planting (MAP), but only 6 MAP in Ntungamo. BSV incidence then increased at a rate of 0.10 plants respectively / infected plant / month at a rate 0.23 plants / infected plant / month in Rakai and Ntungamo respectively. In both sites, spatial analysis showed that there were significant aggregated BSV spatial patterns. New infections were more likely to occur within a 10 rows/coloumns from an old infection. Significant edge effects were also detected in Ntungamo, indicating that there was significant spread from the immediate surroundings (infected established field suggesting need for separation of new fields from old infected fields to delay onset of BSV. Roguing should be frequent enough to offset rate of BSV incidence increase. The study shows that BSV is a slow spreading disease; however, there is sufficient time in this perennial cropping system for it to increase to epidemic levels. It is however, possible to check the advance of the BSV epidemic through phytosanitary measures.
Inheritance of resistance to coffee wilt disease (Fusarium xylarioides Steyaert) in Robusta coffee (Coffea canephora Pierre) and breeding perspectives
(Tree Genetics & Genomes, 2012-08-31) Pascal C. Musoli; Christian Cilas; David Pot; Agnes Nabaggala; Saleh Nakendo; James Pande; André Charrier; Thierry Leroy; Daniel Bieysse
Knowledge on heritability is essential for select- ing varieties resistant against coffee wilt disease caused by Fusarium xylarioides, which is currently devastating coffee in East and Central Africa. Variability of the resistance against coffee wilt disease in Coffea canephora and its inheritance were investigated in three experiments corresponding to a clonal trial involving 20 clones, a 10- parent partial diallel progeny, and a half-sib progeny test. There were significant quantitative genetic variations among the clones and progenies, suggesting polygenic control of the resistance. Around 50–65 % tree mortality was the optimal disease level for calculating heritability and genetic gains. General and specific combining abilities calculated within the optimal disease range for partial diallel analysis were significant. Broad-sense heritability for the same anal- ysis and same disease range was moderate (0.329), and Communicated by A. Dandekar C. Cilas (*) CIRAD, UR 106, TA A-106/02 Avenue Agropolis, 34398 Montpellier Cedex 5, France e-mail: christian.cilas@cirad.fr: A. Charrier SUPAGRO, 2 Pl. P. Viala, 34060 Montpellier Cedex 1, France D. Bieysse CIRAD, UMR BGPI, TA A-54/K Campus Baillarguet, 34398 Montpellier Cedex 5, France corresponding narrow-sense heritability was low (0.112). Broad-sense heritability from clones in the field at the same disease range was also moderate (0.333). Narrow-sense heritability from regression of half-sib progeny means onto parent means in the field and screen house was 0.183 and 0.369, respectively. Selecting tolerant clones for improve- ment against the disease is possible, and genetic gains are possible by using tolerant parents in breeding programs.
In Vitro Antifungal Activity Of Synthetic Dsrna Molecules Against Two Pathogens Of Banana, Fusarium Oxysporum F. Sp. Cubense And Mycosphaerella Fijiensis
(Pest Management Science, 2013-01-03) Francis M Mumbanza; Andrew Kiggundu; Geoffrey Tusiime; Wilberforce K Tushemereirwe; Chuck Niblett; Anna Bailey
BACKGROUND: A key challenge for designing RNAi-based crop protection strategies is the identification of effective target genes in the pathogenic organism. In this study, in vitro antifungal activities of a set of synthetic double-stranded RNA molecules on spore germination of two major pathogenic fungi of banana, Fusarium oxysporum Schlecht f. sp. cubense WC Snyder & HN Hans (Foc) and Mycosphaerella fijiensis Morelet (Mf) were evaluated. RESULTS: All the tested synthetic dsRNAs successfully triggered the silencing of target genes and displayed varying degrees of potential to inhibit spore germination of both tested banana pathogens. When Foc dsRNAs were applied to Foc spores, inhibition ranged from 79.8 to 93.0%, and from 19.9 to 57.8% when Foc dsRNAs were applied to Mf spores. However, when Mf dsRNAs were applied on Mf spores, inhibition ranged from 34.4 to 72.3%, and from 89.7 to 95.9% when Mf dsRNAs were applied to Foc spores. CONCLUSION: The dsRNAs for adenylate cyclase, DNA polymerase alpha subunit and DNA polymerase delta subunit showed high levels of spore germination inhibition during both self- and cross-species tests, making them the most promising targets for RNA-mediated resistance in banana against these fungal pathogens.
High Potassium, Calcium, And Nitrogen Application Reduce Susceptibility To Banana Xanthomonas Wilt Caused By Xanthomonas Campestris Pv. Musacearum
(Plant Disease, 2013-01-06) Atim, M.; Beed, F.; Tusiime, G.; Tripathi, L.; van Asten, P.
The effect of exogenous applications of potassium (K), calcium (Ca), and nitrogen (N) on the susceptibility of four banana cultivars to Ba- nana Xanthomonas wilt (BXW) was studied. Murashige and Skoog (MS) medium with normal concentrations of K at 783 mg/liter, Ca at 121 mg/liter, and N at 841 mg/liter was modified to contain various concentrations of K, Ca, and N. Each nutrient was varied singly, each with three replicate experiments. The concentrations were K at 78, 157, 391, 783, 1,565, and 3,913 mg/liter; Ca at 12, 24, 60, 121, 241, and 603 mg/liter; and N at 84, 168, 420, 841, and 1,682 mg/liter. Plant- lets were generated in vitro on normal MS medium and later exposed to the nutrient concentrations for a total of 8 weeks. Thereafter, they were artificially inoculated with Xanthomonas campestris pv. musa- cearum using an insulin syringe. In each nutrient, plantlets exposed to higher nutrient concentrations significantly (P < 0.0001) accumulated more nutrient in their tissues compared with those exposed to lesser nutrient concentrations. Wilt incidences were significantly reduced, and incubation periods (time from inoculation to appearance of first disease symptoms) increased, with increasing nutrient application. The study lays a background for in vivo studies aimed at management of BXW using nutrients, such as fertilizer application.
Influence of shade systems on spatial distribution and infestation of the Black Coffee Twig Borer on coffee in Uganda
(Uganda Journal of Agricultural Sciences, 2013-04-06) G.H. Kagezi; P. Kucel; J. Kobusingye; L. Nakibuule; R. Wekhaso; G. Ahumuza; P. Musoli; A. Kangire
Studies 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.
Ecological factors influencing incidence and severity of Coffee Leaf Rust and Coffee Berry Disease in major Arabica coffee growing districts of Uganda
(Uganda Journal of Agricultural Sciences, 2013-04-09) R.J. Matovu; A. Kangire; N.A. Phiri; G.J. Hakiza; G.H. Kagezi; P.C. Musoli
Coffee 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.
Agrobacterium Mediated Transformation Of Banana (Musa Sp.) Cv. Sukali Ndiizi (Abb) With A Modified Carica Papaya Cystatin (Cpcys) Gene
(African Journal of Biotechnology, 2013-04-10) Namuddu, A.; Kiggundu, A.; Mukasa, S. B.; Kurnet, K.; Karamura, E.; Tushemereirwe, W.
Conventional banana breeding for pest and disease resistance is a very difficult and slow process due to the limited sources of resistance, sterility of cultivated banana varieties, high polyploidy levels, long cropping cycle and the lack of rapid screening methods. Molecular breeding using the transgenic approach with candidate genes such as cystatins offers an alternative method to banana improvement. Cystatin proteins inhibit the activity of cysteine proteases responsible for the breakdown of dietary proteins in the gut of many pests including nematodes resulting in protein deficiency. In this study, the papaya cystatin gene was introduced into the banana genome. Embryogenic cell suspension (ECS) cultures of the banana cultivar Sukali Ndiizi (ABB) were used as explants material for the successful transformation of banana. The Carica papaya cystatin gene (CpCYS-Mut89) previously modified to improve its inhibitory potential against banana pests was introduced into this cultivar using Agrobacterium tumefaciens, strain LBA4404 and the gus reporter gene was used to observe successful transformation process. We report the successful protocol for routine transformation of this cultivar, which was completed in six months with plant regeneration observed at a frequency of 23%. An additional four months was required to multiply the regenerant lines in order to have at least 20 plants per line for downstream challenging studies. Putatively transgenic plants were analyzed by PCR using hpt and CpCYS-Mut89 specific primers to confirm the presence of transgenes. Out of 28 selected lines, 27 were positive for both hpt and CpCYS-Mut89 transgenes giving 96.4% transformation efficiency. Five lines were then selected on the basis of putative PCR positives and a Southern blot analysis gave hybridization signals with 1 to 4 copy number integration patterns characteristic of Agrobacterium mediated transformation. These results confirm stable gene integration in East African banana cultivar cv. Sukali Ndiizi (genome group ABB) through an efficient Agrobacterium-mediated transformation protocol described for routine use in future improvement of this crop with genes of economic importance.

Browse

Browsing Articles by Issue Date