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. </p><p>Other websites related to the journal include: <a title="" href="" target="_blank"></a></p> African Crop Science Society (Uganda) en-US African Crop Science Journal 1021-9730 Copyright for articles published in this journal is retained by the journal. Changes in endogenous levels of IAA and PAA in rice seed during development, prediction of auxin signaling proteins and docking for its binding efficiency with auxin molecules <p>Indole-3-acetic acid (IAA) and phenyl acetic acid (PAA) are two major physiologically active auxins, found in higher plants. The objective of this study was to evaluate changes in the endogenous levels of IAA and PAA in rice (Oryza sativa) seed and predict probable transporter and efflux (signaling) proteins for docking with auxins from the available rice genome data. IAA and PAA were estimated during rice seed development using sensitive and specific antibodies against each hormone. The levels of IAA and PAA were higher when sink size development was at its peak, suggesting an important role played by the auxin in sink size development of rice seed. Furthermore, auxin binding transporters proteins of rice were confirmed for docking purpose and compared with Arabidopsis and maize proteins. In this context, PAA docked with known IAA proteins; although, docking score of IAA was higher than that of PAA in rice seed. Twelve genes of the auxin efflux carrier (PIN family) of rice were also analysed for phylogeny relatedness with Arabidopsis and maize, to further understanding auxin concentrations and efflux within rice seeds. The predicted PIN proteins for IAA efflux of rice showed docking affinities with PAA, revealed its role in maintaining physiological concentrations of auxins in rice seeds.</p> V.M. Jhala K.S. Chudasama V.S. Thaker Copyright (c) 29 3 325 337 10.4314/acsj.v29i3.1 Efficacité des techniques de greffage pour l’adéquation aux porte-greffes de cajou <p>En absence de semences graines performantes capables d’assurer l’installation de plantations hautement productives, la multiplication végétative des plants d’anacardier reste une alternative viable pour obtenir des plantations homogènes et productives au Bénin. Pour ce fait, deux méthodes de greffage sont davantage utilisées par les pépiniéristes pour la production de plants greffés à savoir&nbsp;: la méthode en fente terminale et la méthode par placage. Cette étude a été menée pour étudier l’influence de ces techniques et de l’origine du greffon sur la croissance et l’aptitude au greffage des porte-greffes en période sèche au Bénin. L’étude a été menée à l’Université Nationale d’Agriculture du Bénin d’août 2019 à février 2020. Les porte-greffes utilisés, ont été produits à partir de semences certifiées du Centre de Recherches Agricoles-Centre du Bénin. Les traitements comprenaient la technique de greffage avec deux variantes (greffage par placage et greffage en fente terminale), et l’origine du greffon avec trois variantes (greffon d’Adakplamè, greffon de Sodji et greffon d’Agozounmè). Les mesures de protection phytosanitaires ont été prises et ont consisté en un traitement de toutes les unités parcellaires avec du&nbsp;Topbio pour combattre les insectes défoliateurs qui ont attaqué les plants greffés au cours de l’essai. Les résultats ont révélé que l’origine du greffon a une influence significative (P&lt;0.05) sur la survie et la croissance en hauteur des plants greffés mais n’a aucun effet significatif sur la reprise et la croissance en diamètre de ces plants. Par contre, la technique de greffage a un effet significatif (P&lt;0.005) sur la reprise et la survie des plants greffés ainsi que sur la croissance en hauteur et en diamètre de ces plants. En effet, un taux de reprise de 64,18 et 52,92 % a été observé respectivement pour le greffage par placage et le greffage en fente terminale mais seulement 44, 81 et 34,65 % des plants ont survécu respectivement pour le greffage par placage et le greffage en fente terminale, un mois après le greffage. En ce qui concerne la croissance des plants greffés, un accroissement moyen de 7,01 cm en hauteur et 1,15 mm en diamètre pour le greffage par placage contre 9,18 cm en hauteur et 1,55 mm en diamètre pour le greffage en fente terminale a été observé. Ces résultats stipulent que le greffage par placage est plus indiqué en saison sèche pour avoir un bon taux de réussite tandis que le greffage en fente terminale est plus indiqué pour une croissance rapide en hauteur et en diamètre des plants greffés.</p> D. Yélouassi D. Yélouassi E. Akpo A. Adandonon I. Balogoun Copyright (c) 29 3 339 354 10.4314/acsj.v29i3.2 Effects of gamma irradiation and ethyl methane sulphonate on morphometric traits and prevalence of common viral diseases and whiteflies in cassava. <p>Cassava (<em>Manihot esculenta</em> Crantz) is an important staple and food security crop for millions of people in Africa. However, its nutritional value is limited; yet its productivity is constrained by several pests and diseases. Induced mutagenesis is one approach with the potential to overcome such biotic stresses. The objective of this study was to assess the variability in morphometric traits and prevalence of common viral diseases and whiteflies in cassava to different doses and concentrations of gamma irradiation and ethyl methane sulphonate (ems) treatments. The effects were assessed on seed germination and growth of stakes, as well as foliar viral disease symptoms and whitefly counts. Radio-sensitivity tests revealed LD50 for sprouting as 37.6Gy for g-irradiation and 0.08% for EMS treatment. There was notable decrease in sprout, epicotyl length, shoot height, petiole length and number of leaf lobes, with increasing g-ray doses and EMS concentrations. Contrastingly, total chlorophyll content increased with increasing doses of g-rays and EMS concentrations. Basing on foliar whitefly counts and disease symptoms, there was a general increase in susceptibility to whitefly infestation and cassava mosaic disease (CMD) incidence. Significantly varying levels of resistance or tolerance to whiteflies and CMD were observed among plantlets derived from irradiated and EMS treated stems, compared to the controls. These findings lay a foundation for more future research on breeding for various traits, including disease resistance in cassava using induced mutagenesis approach.</p> J.K. Baguma E. Ogwok W. Elegba A. Sarkodie S. Otu H.B. Apio R.S. Kawuki A. Bua K. Danso T. Alicai Copyright (c) 29 3 355 371 10.4314/acsj.v29i3.3 Improved callogenesis and plant regeneration from immature male flowers of East African highland banana cv. “Nakitembe” (AAA-EA) <p>Application of biotechnological tools in breeding, germplasm conservation and propagation of the East African bananas (Musa sp.) is limited by the crop’s recalcitrance to somatic embryogenesis. This study was undertaken to establish an efficient callus induction and plant regeneration protocol from immature male flowers in the most commercial and farmer preferred banana cultivar “Nakitembe”. Embryogenic callusing was improved from 2.9% on conventional MA1 culture medium to 4.2% with 500 mg L-1 L-Glutamine, 500 mg L-1 L-Proline and 300 mg L-1 casein hydrolysate supplements. A combination of the three amino acids with Chui N6 salts yielded the highest callusing of 10.2%. Cell suspensions were developed and maintained on conventional MS based MA2 medium. Subsequently, the highest efficiency of embryos germination (up to 80%) was achieved on MA4 medium, supplemented with 2.25 mg L-1 BAP and 0.2 mg L-1 IAA. The developed protocol has been successfully applied in Agrobacterium mediated genetic transformations of this variety.</p> D. Talengera C. Mwami A.F. Tazuba B. Namukwaya Copyright (c) 29 3 373 382 10.4314/acsj.v29i3.4 Occurrence of rice yellow mottle virus resistance breaking isolates in lowland catchment zones of Uganda <p>Rice (<em>Oryza</em> spp; 2n=24.) production in Uganda and Africa in general, is seriously threatened by the Rice yellow mottle virus disease (RYMVD), a disease caused by <em>Rice yellow mottle virus</em> (RYMV) within the genus Sobemovirus; family Sobemoviridae. This study investigated the existence and distribution of resistance-breaking RYMV pathotype in the three major lowland rice catchment areas in Uganda. Four known rice accessions resistant to Rice yellow mottle virus (RYMV) namely; Gigante, Tog5672, Tog5674 and Tog5681, carrying resistant allele’s rymv1-2, rymv1-4 &amp; RYMV3, rymv1-5 and rymv1-3, respectively, were tested for their response to different RYMV isolates. The isolates were collected from three major lowland rice catchment areas of Doho, Kibimba, and Olweny in Uganda. Out of 100 leaf samples collected from the field and assayed for RYMV and confirmed to be positive using RT-PCR, 83 isolates induced symptoms on IR64- the RYMV susceptible line. Seventy-seven (92.8%) isolates were able to overcome resistance in at least one of the four differential rice accessions, as confirmed by the presence of RYMV symptoms; while 6 (7.2%) isolates were asymptomatic. Variation in time (days) for symptom development post-inoculation (dpi) and AUDPC were observed. Symptoms appeared within 5-7 days on IR64; while it took on average 11, 18, 36, and 18 days to appear on Gigante, Tog5672, Tog5674 and Tog5681, respectively. The highest AUDPC was observed on IR64 (254.7); while the lowest was observed on Tog5681 (74.1). Two major patho-groups were observed; those that broke down resistance in Gigante only (25.3%) and Gigante &amp; Tog5672 (33.7%). Five isolates from Doho (Budaka &amp; Bugiri districts) and Kibimba (Butaleja district) catchment areas broke down RYMV resistance in three accessions i.e. (Tog5681, Gigante &amp; Tog5672) and (Tog5674, Gigante &amp; Tog5672), respectively. Resistance breaking isolates were confirmed in all &nbsp;the three sampled catchment zones, however, Doho and Kibimba had some unique isolates that broke down resistance in accessions carrying resistance allele rymv 1-3 and rymv1-5 in addition to rymv1-2. Results from this study showed that RYMV isolates in Uganda can break down resistance conferred by the&nbsp;rymv1-2 resistance gene allele. However, accessions Tog5681 and Tog5674 seem to hold stable RYMV resistance and, thus are recommended for RYMV breeding.</p> I. Ramathani S.B. Mukasa T. Alicai S. Nanyiti J. Lamo Copyright (c) 29 3 383 400 10.4314/acsj.v29i3.5 Development of white common beans for the processing industry in East Africa: Adaptability, resistance to selected diseases, cooking time and canning quality <p>Common bean (<em>Phaseolus vulgaris</em> L.) provides dietary protein, energy, fiber, and micronutrients, especially iron and zinc to over 800 million people in Africa and Latin America. The crop has various seed types. White beans are very popular for the processing industry. This study aimed to investigate the agronomic performance, canning quality, cooking time (COOKT) and response to root rots (<em>Fusarium cuneirostrum </em>and <em>Pythium ultimum</em>) and angular leaf spot (ALS; <em>Pseudocercospora griseola</em>) diseases among 151 drought tolerant small and large seeded white bean genotypes from trials conducted between 2013 to 2018 in East Africa. Significant (P&lt;0.001) differences existed among the genotypes for response to the three pathogens, COOKT and canning quality traits. Resistance to each of the pathogens was expressed in 24-75% of the genotypes, while dual resistance to any two pairs of the pathogens occurred in 10-44% of the genotypes. Four genotypes; ICNBunsixSxB405/4C-1C-1C-88, RAZ-11, ETSNAP18 and ETSNAP3 expressed resistance to the three pathogens but had COOKT of 46-56 minutes (based on a Matson cooker), and below average canning quality. They are recommended as sources of diseases resistance but could be further improved for COOKT and canning quality. Sixty-eight genotypes had COOKT &lt;50 minutes while 24 expressed good to excellent visual canning quality. Some phenotypes: RAZ-120, RAZ36-Caballero, NavyLine-60, NavyLine-25, ZABR16573-25F22, ZABR16575-60F22, ETSNAP33, Bifort small seeded-15 and ZABR16574-37F22, that were cooked in &lt;45 minutes, exhibited good to excellent canning quality and expressed resistant to intermediate diseases resistance responses. These may be used as parental lines and/or fast tracked for variety release through regional trials.&nbsp;</p> W. Amongi F. Kato A. Male S. Musoke C. Acam A. Kabwama B. Nakyanzi S. Sebuliba M. Williams J. Mbiu G. Baguma C. Mukankusi Copyright (c) 29 3 401 431 10.4314/acsj.v29i3.6