African Crop Science Journal <p>The <em>African Crop Science Journal,</em> a quarterly publication, publishes original research papers dealing with all aspects of crop agronomy, production, genetics and breeding, germplasm, crop protection, post harvest systems and utilisation, agro-forestry, crop-animal interactions, information science, environmental science and soil science. It also publishes authoritative reviews on crop science and environmental issues by invitation. It is bilingual, publishing in either English or French. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;</p> <p>Other websites related to the journal include: <a title="" href="" target="_blank" rel="noopener"></a></p> en-US Copyright for articles published in this journal is retained by the journal. (Dr. J.S. Tenywa) (Editor) Wed, 30 Mar 2022 08:13:28 +0000 OJS 60 Incidence, severity and distribution of yellow leaf curl disease of tomato in Kenya <p>Tomato (<em>Solanum lycopersicum</em> L.) is an important fruiting vegetable grown in Kenya because of its commercial and high nutritional value. Viruses are a major constraint to tomato production in tropics and sub tropics, eliciting symptoms like stunting, leaf mosaic, distortion, chlorosis, mottling, and vein clearing similar to those caused by abiotic factors. Although begomoviruses are known to cause tomato yellow leaf curl disease (TYLCD) in Kenya, there is limited knowledge on the disease status in tomato fields. The objective of this study was to determine the incidence and distribution of TYLCD in Kenya using the double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) technique. A survey was carried out in eight major tomato growing regions (259 fields) in Kenya during September to December, 2018. Presence of tomato yellow leaf curl virus was further confirmed using DAS–ELISA. The disease was present across all the counties surveyed and its prevalence, incidences and severity varied across the counties and among the fields. The mean TYLCD prevalence ranged from 19.5% in Bungoma County, to 64% in Kwale County. There was significant difference (P&lt;0.05) in disease incidences among the varieties sampled and the incidence was lower in plants grown from hybrids seed compared to conventional varieties. Mean disease severity was significant (P&lt;0.05) and ranged from 0.18 to 2.20. Most farmers planted non-hybrid seeds. There is need for further determination of the diversity of begomoviruses infecting tomato using other techniques to provide more information towards breeding TYLCD-resistant tomato varieties.</p> E.K. Avedi, A.O. Adediji, D.C. Kilalo, F.M. Olubayo, I. Macharia Copyright (c) Temporal and spatial dynamics of Bemisia tabaci populations and cassava viral diseases on selected whitefly resistant cassava genotypes in Uganda <p><em>Bemisia tabaci</em> (Gennadius) (Hemiptera: Aleyrodidae) is a pest that causes widespread damage on cassava (<em>Manihot esculanta</em> Crantz), a staple food crop for millions of households in sub-Saharan Africa.<em> Bemisia tabaci</em> also acts as a vector responsible for spreading plant viruses that cause two of the most economically damaging diseases in cassava; namely cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). The objective of this study was to determine the population dynamics of <em>B. tabaci</em> on whitefly resistant cassava genotypes in different agro-ecologies in Uganda. Data were collected once a month, for six months on adult whitefly populations, cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) incidence and symptom severity. The results obtained indicated that cropping season (2015 and 2016), agro-ecology, cassava age and genotypes strongly (P&lt;0.001) influenced the population of adult whitefly. Moderate (47.44% ± 0.7821) and high (72.04% ± 0.6916) overall means incidences of CBSD recorded across agro-ecologies on the whitefly resistant genotypes in 2015 and 2016 trials, respectively, were likely due to use of cutting-infected planting materials that were not detected through visual inspection at trial establishment. The analysis further revealed that the interaction effect of genotype, agro-ecology and crop age (months after planting: MAP) had a highly significant influence (P&lt; 0.001) on whitefly abundance and high significant effect (P&lt;0.05) on CMD incidence and severity. The CMD and CBSD incidence as well as symptom severity increased with crop age from 3 months after planting across agro-ecologies. The study demonstrates that whitefly population dynamics and viral disease incidence are influenced by cassava genotypes, agro-ecological differences and crop age (MAP). Information generated could be used to guide the development of appropriate area-specific control strategies to mitigate the effect of whitefly and whitefly-transmitted viral diseases in cassava. </p> C. Gwandu, M. Ochwo-Ssemakula, J. Kabissa, P. Sseruwagi Copyright (c) Introgression of drought tolerance root traits into Kenyan commercial chickpea varieties using marker assisted backcrossing <p>Roots play critical roles in enhancing drought tolerance, more so under terminal drought conditions. The objective of this study was to introgress drought tolerant root traits into Kenyan chickpea varieties through marker assisted backcrossing (MABC). Eight simple sequence repeat (SSR) markers, linked to quantitative trait loci (QTL) for root traits, were used to screen parents at ICRISAT in India, and 1144 single nucleotide polymorphic (SNPs) markers at Legume Genomics Centre in the United Kingdom. Crosses were made between two selected varieties, ICCV 92944 (Chania Desi II) and ICCV 00108 (LDT 068); and ICC 4958, QTL donor parent. Polymorphic SSR and SNP markers were used to select offspring with root QTL at F1, BC1F1, and BC2F1, and later advanced to BC2F3. BC2F3 families were evaluated for root traits at Egerton University in Kenya in a pot experiment under rain shelter. The BC2F3 families were significantly (P&lt;0.05) different for root dry weight (RDW), shoot dry weight (SDW), total plant dry weight (PDW), and root to shoot dry weight (R/S) ratio (R/S) for Chania Desi II x ICC 4958; while R/S was significantly different for LDT 068 x ICC 4958. Root length density (RLD) and RDW were positively and significantly (P&lt;0.05) correlated with most of the traits, indicating its usefulness in the indirect selection of these traits. The utilisation of MABC is an effective and efficient method of introgressing complex root traits into commercial lines, expected to improve yields under drought. There is need for deployment of marker-assisted breeding in difficult to phenotypically select traits.</p> A.J. Kosgei, P.K. Kimurto, P.M. Gaur, M.A. Yeboah, S.K. Offei , E.Y. Danquah Copyright (c) Characterisation of potato varieties commonly grown in Uganda for food processing suitability <p>Potato (<em>Solanum tuberosum</em> L.) is an important crop for food and income generation in Uganda. However, lack of data on the physico-chemical characteristics of the major potato varieties to support industrial-level processing is one of the major limitations. To bridge the existing information gap, nine major potato varieties grown in Uganda; namely: Cruza, Kachpot1, Kimuli, Kinigi, Mbumbamagara, Rutuku, Rwashaki, Rwangume and Victoria were characterised to generate information on physical, chemical and processing traits. The results indicated that Kinigi had the highest dry matter (27.2%); whereas Rutuku had the lowest (19.28 %). Most varieties had tubers of medium size (50-60 mm), round in shape with medium eye depth. Kimuli recorded the highest (0.55 g 100 g-1 FW) levels of reducing sugars; whereas Kinigi had the lowest (0.02 g 100 g-1 FW). Cluster analysis separated the varieties into three groups; group 1 included varieties Cruza, Kimuli and Rwangume, which were found unsuitable for processing French fries and crisps due to high levels of reducing sugars; but are excellent candidates for preparation of mashed potato and salads. The second group included Kachpot1, Kinigi and Rwashaki and was found suitable for processing French fries, crisps and starch due to high dry matter and low reducing sugars. Group 3 included Mbumbamagara, Rutuku and Victoria and was found only suitable for production of potato flour, mashed potato and salads due to low dry matter content and small tubers.The information generated by the study is important in guiding interventions aimed at improving the potato value chain in Uganda and its contribution to socio-economic development.</p> N.H.B. Kajunju, A. Atukwase, G.A. Tumuhimbise , J. Mugisha Copyright (c) Performance of three morphotypes of garlic using quantative traits based on bulb characters in Niger Republic <p>Garlic (<em>Allium sativum</em> L.) is a bulbous plant from the Alliaceae family, mainly produced in the dry seasons under irrigation in Niger. The objective of this study was to assess garlic morphotypes for their agronomic performance traits. The experiment was conducted at the Université de Zinder in Niger Republic, in a randomised complete block design during the dry season of 2019-2020. Data were collected on bulb diameter, bulb length, bulb weight, number of cloves per bulb, clove diameter, clove length, clove weight, number of outer clove lets per clove, outer clove lets diameter, outer clove lets length, and outer clove lets weight. There were significant differences for all characters, except bulb weight, clove diameter and number of outer clove lets per clove. The morphotypes Pink and Dark purple revealed good performances and could be useful for a breeding programme. </p> R. Abdou, T.K.A. So, A. I. Halilou, Y. Bakasso Copyright (c) Influence of scion length and point of attachment on rootstock on survival and growth of grafted soursop <p>Soursop (<em>Annona muricata</em>) is a multipurpose fruit tree species, which is mostly propagated by seeds, thus producing plants that exhibit various degree of variability. The objective of this study was to assess the influence of scion length and point of attachment on rootstock on survival and growth on grafted Annona muricata. Varying points were marked out on the rootstock from the base of the plant and varying scion lengths (5, 10 and 15 cm) were collected. The modified cleft method of grafting was adopted and this was monitored daily for freshness and appearance of new shoot. At the end of two months, survived grafted plants were removed and arranged under a weaning shed, where they were further monitored for number of leaves, height of graft, diameter of scion and rootstock. Results showed that scion length varied significantly (P&lt;0.05) for all the parameters assessed. The effect of point of attachment on rootstock was also significant on the number of leaves, as well as scion collar diameter. The effect rootstock on graft height and rootstock collar diameter was not significant. The interactive effect of scion and rootstock was significant (P&lt;0.05) for all parameters, except height of graft. For successful graft, survival and growth of grafted<em> A</em>. <em>muricata</em>, 10 - 15 cm long scion should be used and this should be inserted at the upper part (15 cm) of the rootstock.</p> F.B. Yakubu, V.I. Alaje, A.A. Olaniyi, M.O. Nola, M.A. Odewale, O.O. Fadulu, K.K. Adeniyi Copyright (c) Effect of ridging and intercropping on sorghum productivity in arid and semi-arid lands of eastern Kenya <p>Soil moisture deficit is a key constraint to sorghum (Sorghum bicolor) productivity in arid and semi-arid lands globally. The objective of this study was to determine the effect of ridging and sorghum-bean intercropping (additive system) on soil moisture conservation and sorghum productivity. Sorghum (gadam) was grown either as a sole crop or intercropped with two bean (<em>Phaseolus vulgaris</em> L.) varieties (KATx56 and KAT B1), under two types of ridging (open ridges and tied ridges), and a control without ridges for two years. The study was set up in split plot arrangement, in a randomised complete block design, at the Kenya Agricultural and Livestock Research Organization, Kiboko, in 2019 and 2020. There was no significant interaction between ridging and intercropping. Soil moisture content increased by 11-26% due to ridging; and decreased by -11 and -7% due to sorghum-KAT B1 and Sorghum-KAT X56 intercropping, respectively. Higher moisture content due to ridging was attributed to formation of basin-like structures, which increased water harvesting and infiltration compared to the no ridges where surface run-off was predominant. The highest moisture content was attained on sole bean, followed by sole sorghum and then sorghum/bean intercropping. The decrease in moisture content in intercrops of sorghum/bean relative to their specific sole crops was attributed to higher crop density, which reduced crop spacing, thus triggering competition for available soil moisture. The highest sorghum grain and equivalent yields were obtained in the ridged plots. Intercropping resulted into decrease in sorghum grain yield, but led to increase in sorghum equivalent yield (SEY) and Land Equivalent Ratio (LER). The results show that both ridging and intercropping are suitable for higher water use efficiency and land productivity in ASALs of Kenya.</p> D. Musyimi, E.O. Ouma, E.O. Auma, E.J. Too, L. Ngode, C.K. Kamau , S. Gudu Copyright (c) Field performance of Shrunken-2maize hybrids and its relationship with genetic distance of their inbred parents <p>Maize (<em>Zea mays</em> L.) is an important crop in West and Central Africa, where flint and dent types are the widely cultivated and used as food, feed and raw materials in industries. Sweet maize, the generic term used for maize types with elevated levels of sugar in their kernels, is increasingly popular in Nigeria and other countries of West Africa. This study evaluated the field performance of some super-sweet <em>shrunken-2 </em>(sh-2 ) maize hybrids and determined its relationship with SSR-based genetic distance of their inbred parents. A total of 21<em> shrunken-2</em> maize hybrids and seven <em>shrunken-2</em> maize hybrid checks were evaluated. Analysis of variance was carried out on data collected and correlation analysis between the genetic distance of parental lines and agronomic traits of their hybrids. There were significant differences (P &lt; 0.01) among the hybrids for all agronomic traits studied. Field emergence ranged from 28.2 to 97.4%; while fresh cob weight and husk cover (1-9) ranged from 0.05 to 0.17 and 2.7 to 6.7 g plant-1, respectively. Among the hybrids, UI1 x UI75 was the most promising, combining high emergence with high fresh cob yield, good husk cover, resistance to endemic foliar diseases, good plant aspect and moderate ear aspect. Genetic distance between parental inbred lines was not useful for predicting hybrid performance among the sets of <em>shrunken-2</em> inbred lines considered. The parental lines, however, have potential for use in<em> shrunken-2</em> maize breeding programmes.</p> O.O. Oladejo, V.O. Adetimirin, J.E. Iboyi Copyright (c)