Quantitative Trait Loci Mapping in Maize for Resistance to Larger Grain Borer

Storability of maize grain is constrained by the larger grain borer (LGB) (Prostephanus truncatus). Host plant resistance is the most feasible way to manage LGB among smallholder farmers. Breeding for resistance to this pest inmaize is dependent on understanding genetic mechanisms underlying the resistance. The objective of this study was to map quantitative trait loci (QTL) associated with LGB resistance in tropical maize. A mapping populationof 203 F2:3 derived progenies was developed from a cross between susceptible and resistant inbred lines.The F2:3 progenies were crossed to a tester and testcrosses evaluated across six environments, followed by screening for resistance to LGB. Data was collected on husk cover tip length, and grain texture in the field. Biochemical traits were analyzed on the maize grain. Harvested grain was evaluated for resistance and data recorded on grain damage, weight loss, and several insects. Grain hardness was measured as a putative trait of resistance. Univariate analysis of variance for all the traits was done using the general linear model of the statistical analysis system.Genetic mapping was done using Joinmap 4, while QTL analysis was done using PLABQTL. The QTL for resistance were mapped to 6 out of the ten chromosomes. QTL for resistance traits were located in chromosomes 1, 5 and 9.Chromosome 1 had a common QTL linked to protein content, grain hardness, and husk cover tip length. Additive genetic effects were prevalent in all detected QTL. Overall, the studies show that breeding for resistance to LGB is possible

Cassava whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), in sub-Saharan African farming landscapes: a review of the factors determining abundance

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a pest species complex that causes widespread damage to cassava, a staple food crop for millions of smallholder households in Sub-Saharan Africa. Species in the complex cause direct feeding damage to cassava and are the vectors of multiple plant viruses. Whilst significant work has gone into developing virus-resistant cassava cultivars, there has been little research effort aimed at understanding the ecology of these insect vectors. In this review we critically assess the knowledge base relating to factors that may lead to high population densities of Sub-Saharan African (SSA) Bemisia tabaci species in cassava production landscapes of East Africa. We focus first on empirical studies that have examined biotic or abiotic factors that may lead to high populations. We then identify knowledge gaps that need to be filled to deliver long-term sustainable solutions to manage both the vectors and the viruses that they transmit. We found that whilst many hypotheses have been put forward to explain the increases in abundance witnessed since the early 1990s, there are little available published data and these tend to have been collected in a piecemeal manner. The most critical knowledge gaps identified were: (i) understanding how cassava cultivars and alternative host plants impact B. tabaci population dynamics and its natural enemies; (ii) the impact of natural enemies in terms of reducing the frequency of outbreaks and (iii) the use and management of insecticides to delay or avoid the development of resistance. In addition, there are several fundamental methodologies that need to be developed and deployed in East Africa to address some of the more challenging knowledge gaps

Responses of tropical maize landraces to damage by Chilo partellus stem borer

The potential to manage insect pests using host-plant resistance exists, but has not been exploited adequately. The objective of this study was to determine the resistance of 75 tropical maize landraces through artificial infestation with Chilo partellus Swinhoe. The trial was laid in alpha-lattice design and each seedling was infested with five neonates three weeks after planting, over two seasons in 2009 and 2010. The number of exit holes, tunnel length, ear diameter, ear length, plant height, stem diameter, stem lodging and grain yield were measured and a selection index computed. GUAT 1050 was the most resistant with an index of 0.56, while BRAZ 2179 was the most susceptible with an index of 1.66. Ear characteristics were negatively correlated with damage parameters. The principal component biplot suggested that exit holes, cumulative tunnel length, leaf damage, cob diameter, stem lodging, selection index, ear and plant height contributed 71.2% of the variation in resistance. The mean number of exit holes and tunnel length for resistant landraces and resistant hybrid checks were similar; at 5.5 and 2.48 cm, respectively. The identified resistant landraces (GUAT 1050, GUAT 280, GUAT 1093, GUAT 1082, GUAT 1014, CHIS 114, and GUAN 34) could be used to develop C. partellus stem borer-resistant maize genotypes.Key words: Chilo partellus, ear length, exit holes, stem borer resistance, tunnel length

Protein and amino acid composition of different quinoa (Chenopodium quinoa willd) cultivars grown under field conditions in Ethiopia, Kenya, Uganda, and Zambia

Protein-energy malnutrition (PEM) remains a public health concern in most developing nations. In Africa, PEM can be attributed to monotonous diets based on cereals, roots, and tubers, with little or no protein of animal origin. Diversifying cropping systems to include protein dense pseudo-cereals such as Quinoa (Chenopodium quinoa Willd.) could help provide more protein in the diet of vulnerable populations. Quinoa is a crop with potential for biodiversification because it has a high nutritional value; however, it is underutilized in Africa, and information about the nutritional quality of the grain grown in contrasting environments is limited. Within the framework of FAO’s commemoration of 2013 as the ‘The International Year of the Quinoa’ (IYQ), a Technical Cooperation Programme (TCP) project was developed with some African countries to assess the capacity of quinoa to adapt to different agro-ecological regions and the nutritional quality of the resulting grain. For this study, we evaluated the protein content and amino acidprofile of three genotypes of quinoa that had been grown under diverse altitudes, soil, and climate conditions in Ethiopia, Kenya, Uganda, and Zambia. The mean protein content (g/100g) of Kancolla, Titicaca and BBR varieties grown in Africa ranged from 14.33 ±0.20 to 17.61 ±0.55, 14.23 ±0.25 to 16.65 ±0.55, and 13.13 ±0.2 to 16.23 ±0.49, respectively. On the other hand, the protein content (g/100g) of Kancolla, Titicaca, and BBR seeds grown in Peru was 13.80 ±0.10, 17.43 ±0.31, and 17.07 ±0.11, respectively. The Kancolla variety [grown in Ethiopia and Kenya] had a significantly higher protein content than that obtained from Peru [P < 0.001]. Regarding the profile of essential amino acids, Quinoa is essentially richer in methionine than most cereals. Levels of methionine were lower in the seeds grown in Africa compared to those from Peru [P < 0.001]. In terms of environmental influences, the protein content was relatively higher in quinoa seeds grown in high-altitude areas, where soils have a low pH and high nitrogen content. We conclude that Quinoa can be introduced to Africa, especially to high altitudes and warm regions where the soil has a low pH and high nitrogen content. Thecrop would be ideal for diversifying local diets. Key words: Africa, Agro-ecology, Chenopodium quinoa, protein, amino acid content, biodiversity, diet

Protein and amino acid composition of different quinoa (chenopodium quinoa willd) cultivars grown under field conditions in Ethiopia, Kenya, Uganda, and Zambia

Protein-energy malnutrition (PEM) remains a public health concern in most developing nations. In Africa, PEM can be attributed to monotonous diets based on cereals, roots, and tubers, with little or no protein of animal origin. Diversifying cropping systems to include protein dense pseudo-cereals such as Quinoa (Chenopodium quinoa Willd.) could help provide more protein in the diet of vulnerable populations. Quinoa is a crop with potential for biodiversification because it has a high nutritional value; however, it is underutilized in Africa, and information about the nutritional quality of the grain grown in contrasting environments is limited. Within the framework of FAO’s commemoration of 2013 as the ‘The International Year of the Quinoa’ (IYQ), a Technical Cooperation Programme (TCP) project was developed with some African countries to assess the capacity of quinoa to adapt to different agro-ecological regions and the nutritional quality of the resulting grain. For this study, we evaluated the protein content and amino acid profile of three genotypes of quinoa that had been grown under diverse altitudes, soil, and climate conditions in Ethiopia, Kenya, Uganda, and Zambia. The mean protein content (g/100g) of Kancolla, Titicaca and BBR varieties grown in Africa ranged from 14.33 ±0.20 to 17.61 ±0.55, 14.23 ±0.25 to 16.65 ±0.55, and 13.13 ±0.2 to 16.23 ±0.49, respectively. On the other hand, the protein content (g/100g) of Kancolla, Titicaca, and BBR seeds grown in Peru was 13.80 ±0.10, 17.43 ±0.31, and 17.07 ±0.11, respectively. The Kancolla variety [grown in Ethiopia and Kenya] had a significantly higher protein content than that obtained from Peru [P < 0.001]. Regarding the profile of essential amino acids, Quinoa is essentially richer in methionine than most cereals. Levels of methionine were lower in the seeds grown in Africa compared to those from Peru [P < 0.001]. In terms of environmental influences, the protein content was relatively higher in quinoa seeds grown in high-altitude areas, where soils have a low pH and high nitrogen content. We conclude that Quinoa can be introduced to Africa, especially to high altitudes and warm regions where the soil has a low pH and high nitrogen content. The crop would be ideal for diversifying local diets

Conservation Farming and Changing Climate: More Beneficial Than Conventional Methods for Degraded Ugandan Soils

The extent of land affected by degradation in Uganda ranges from 20% in relatively flat and vegetation-covered areas to 90% in the eastern and southwestern highlands. Land degradation has adversely affected smallholder agro-ecosystems including direct damage and loss of critical ecosystem services such as agricultural land/soil and biodiversity. This study evaluated the extent of bare grounds in Nakasongola, one of the districts in the Cattle Corridor of Uganda and the yield responses of maize (Zea mays) and common bean (Phaseolus vulgaris L.) to different tillage methods in the district. Bare ground was determined by a supervised multi-band satellite image classification using the Maximum Likelihood Classifier (MLC). Field trials on maize and bean grain yield responses to tillage practices used a randomized complete block design with three replications, evaluating conventional farmer practice (CFP); permanent planting basins (PPB); and rip lines, with or without fertilizer in maize and bean rotations. Bare ground coverage in the Nakasongola District was 187 km2 (11%) of the 1741 km2 of arable land due to extreme cases of soil compaction. All practices, whether conventional or the newly introduced conservation farming practices in combination with fertilizer increased bean and maize grain yields, albeit with minimal statistical significance in some cases. The newly introduced conservation farming tillage practices increased the bean grain yield relative to conventional practices by 41% in PPBs and 43% in rip lines. In maize, the newly introduced conservation farming tillage practices increased the grain yield by 78% on average, relative to conventional practices. Apparently, conservation farming tillage methods proved beneficial relative to conventional methods on degraded soils, with the short-term benefit of increasing land productivity leading to better harvests and food security

Nature and dynamics of climate variability in the uganda cattle corridor

The study was conducted in the districts of Nakaseke and Nakasongola stratified into four farming systems of crop dominancy, pastoralists, mixed crop and livestock and fishing. The study was guided by two research questions: (1) how do community residents perceive climate change/variability? (2) What is the trend and nature of climate variability and how does it compare with people’s perceptions? Ninety eight percent (98%) of the respondents reported that the routine patterns of weather and climate had changed in the last 5 to 10 years and it has become less predictable with sunshine hours being extended and rainfall amounts being reduced. This compared well with the analyzed secondary data. Over 78% respondents perceived climate change and variability to be caused by tree cutting other than the known scientific reasons like increase in industrial fumes or increased fossil fuel use. Climate data showed that over the period 1961 to 2010 the number of dry spells within a rainfall season had increased with the most significant increase observed in the first rainfall season of March to May as compared to the season of September to November. The first dry season of June/July to August is short while the second dry season of December to February is long during the study period. The two rainfall seasons of March to May and September to November seem to be merging into one major season from May to November. Temperature data shows a significant increasing trend in mean annual temperatures with the most increase observed in the mean annual minimum temperatures than the maximum temperatures.Key words: Climate variability, community perceptions, Uganda cattle corridor, dry spells

EFFECT OF TEMPERATURE AND CASSAVA GENOTYPE ON THE DEVELOPMENT, FECUNDITY AND REPRODUCTION OF Bemisia tabaci SSA1

The Bemisia tabaci complex is currently recognised as key agricultural pests that cause economic damage globally. Temperature is the most important driver of changes in behaviour, abundance and distribution of insect pests, including the whitefly (Bemisia tabaci). The objective of this study was to evaluate the development, fecundity and reproduction of B. tabaci SSA1 on cassava genotypes under a range of temperatures. A laboratory study was conducted using three cassava genotypes (Alado alado, NAROCASS 1 and NASE 14) at five constant temperatures (16, 20, 24, 28 and 32 \ub0C). The parameters assessed included development duration, survival, fecundity and population parameters for B. tabaci SSA1. Temperature had significant effects (P&lt;0.001) on development time, survival and fecundity of B. tabaci; while cassava genotype had no effect (P&gt;0.05). An inverse relationship was observed between development time and temperature for all stages across all cassava genotypes. The total life cycle was 63.8 days at 16 \ub0C and 17.9 days at 32 \ub0C on NAROCASS 1. Survival for each stage throughout the entire life cycle increased with temperature and was highest at 32 \ub0C, although this was not significantly different from that at 28 \ub0C. Fecundity increased with temperature and was highest at 32 \ub0C on all cassava genotypes. For all cassava genotypes, the intrinsic rate of increase (rm), finite rate of increase (\u3bb) and net reproductive rate (Ro) increased with temperature, while mean generation time (T) reduced following a similar pattern. At 32 \ub0C, rm, Ro, \u3bb and T were 0.2, 48.7, 1.2 and 22.6 days, respectively; compared to 0.01, 1.9, 1.0 and 71.2 days at 16 \ub0C on Alado alado. Therefore, the ideal development temperature for B. tabaci SSA1 is 32 \ub0C. Thus, there is a risk of accelerated future expansion of B. tabaci SSA1 populations globally, with global warming and climate variability.Le complexe Bemisia tabaci est actuellement reconnu comme un ravageur agricole cl\ue9 causant des dommages \ue9conomiques \ue0 l\u2019\ue9chelle mondiale. La temp\ue9rature est le facteur le plus important des changements de comportement, d\u2019abondance et de r\ue9partition des insectes ravageurs, y compris l\u2019aleurode (Bemisia tabaci). L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer le d\ue9veloppement, la f\ue9condit\ue9 et la reproduction de B. tabaci SSA1 sur des g\ue9notypes de manioc sous une gamme de temp\ue9ratures. Une \ue9tude en laboratoire a \ue9t\ue9 men\ue9e en utilisant trois g\ue9notypes de manioc (Alado alado, NAROCASS 1 et NASE 14) \ue0 cinq temp\ue9ratures constantes (16, 20, 24, 28 et 32 \ub0C). Les param\ue8tres \ue9valu\ue9s comprenaient la dur\ue9e du d\ue9veloppement, la survie, la f\ue9condit\ue9 et les param\ue8tres de population pour B. tabaci SSA1. La temp\ue9rature a eu des effets significatifs (P&lt;0,001) sur le temps de d\ue9veloppement, la survie et la f\ue9condit\ue9 de B. tabaci, tandis que le g\ue9notype du manioc n\u2019a eu aucun effet (p&gt;0,05). Une relation inverse a \ue9t\ue9 observ\ue9e entre le temps de d\ue9veloppement et la temp\ue9rature pour tous les stades dans tous les g\ue9notypes de manioc. Le cycle de vie total \ue9tait de 63,8 jours \ue0 16 \ub0C et de 17,9 jours \ue0 32 \ub0C sur NAROCASS 1. La survie pour chaque \ue9tape tout au long du cycle de vie entier augmentait avec la temp\ue9rature et \ue9tait maximale \ue0 32 \ub0C. Cependant, la survie \ue0 28 \ub0C n\u2019\ue9tait pas significativement diff\ue9rente de celle observ\ue9e \ue0 32 \ub0C. La f\ue9condit\ue9 augmentait avec la temp\ue9rature et \ue9tait maximale \ue0 32 \ub0C sur tous les g\ue9notypes de manioc. Pour tous les g\ue9notypes de manioc, le taux d\u2019accroissement intrins\ue8que (rm), le taux d\u2019accroissement fini (\u3bb) et le taux net de reproduction (Ro) ont augment\ue9 avec la temp\ue9rature, tandis que le temps de g\ue9n\ue9ration moyen (T) a diminu\ue9 selon un sch\ue9ma similaire. A 32 \ub0C, rm, Ro, \u3bb et T \ue9taient respectivement de 0,2, 48,7, 1,2 et 22,6 jours ; contre 0,01, 1,9, 1,0 et 71,2 jours \ue0 16 \ub0C sur Alado alado. Par cons\ue9quent, d\u2019apr\ue8s cette \ue9tude, la temp\ue9rature de d\ue9veloppement id\ue9ale pour B. tabaci SSA1 est de 32 \ub0C. Ainsi, il existe un risque d\u2019expansion future acc\ue9l\ue9r\ue9e des populations de B. tabaci SSA1 \ue0 l\u2019\ue9chelle mondiale, avec le r\ue9chauffement climatique et la variabilit\ue9 climatique

The use of common bean (Phaseolus vulgaris ) traditional varieties and their mixtures with commercial varieties to manage bean fly (Ophiomyia spp .) infestations in Uganda

The bean fly (Ophiomyia spp.) is considered the most economically damaging field insect pest of common beans in Uganda. Despite the use of existing pest management approaches, reported damage has remained high. Forty-eight traditional and improved common bean varieties currently grown in farmers’ fields were evaluated for resistance against bean fly. Data on bean fly incidence, severity and root damage from bean stem maggot were collected. Generalized linear mixed model (GLMM) revealed significant resistance to bean fly in the Ugandan traditional varieties. A popular resistant traditional variety and a popular susceptible commercial variety were selected from the 48 varieties and evaluated in pure and mixed stands. The incidence of bean fly infestation on both varieties in mixtures with different arrangements (systematic random versus rows), and different proportions within each of the two arrangements, was measured and analysed using GLMMs. The proportion of resistant varieties in a mixture and the arrangement type significantly decreased bean fly damage compared to pure stands, with the highest decrease in damage registered in the systematic random mixture with at least 50 % of resistant variety. The highest reduction in root damage, obvious 21 days after planting, was found in systematic random mixtures with at least 50 % of the resistant variety. Small holder farmers in East Africa and elsewhere in the world have local preferences for growing bean varieties in genetic mixtures. These mixtures can be enhanced by the use of resistant varieties in the mixtures to reduce bean fly damage on susceptible popular varieties