Tomato breeding in sub-Saharan Africa - Challenges and opportunities: A review

Successful tomato ( Solanum lycopersicum ) production depends on availability of improved cultivars that can withstand biotic and abiotic pressures inflicted by the environment. This paper explores the challenges in tomato breeding and identifies opportunities that can be explored to improve tomato breeding initiatives in Africa. The review focuses on primary sources of information and notes that few existing tomato breeding institutions in Africa can drive a vibrant tomato industry and its downstream enterprises. This is coupled with inadequate breeding policies regarding varietal release and protection, negative effects of climate change, emergence of pests and diseases that impact negatively on tomato production efforts in Africa. There is a chance to tap in the diversity currently existing in wild tomato relatives, and to introduce and strengthen tomato breeding at various research institutes, through capacity building. Furthermore, there is need for Africa to embrace long term breeding strategies such as pre-breeding and the use of modern breeding technologies, if tomato production is to be sustained. Key production challenges in Africa include high incidences of fungal diseases and pests, low soil fertility, limited tomato breeding, climate change induced stresses and lack of adequate inputs due to prohibitive costs. Tomato production opportunities arise as a result of increase in human populations and consequently mounting consumer demands for nutrition and potential use of improved technologies such as CRISPR and gene sequence technologies to produce novel genotypes.La r\ue9ussite de la production de tomates ( Solanum lycopersicum ) d\ue9pend de la disponibilit\ue9 de cultivars am\ue9lior\ue9s qui peuvent r\ue9sister aux pressions biotiques et abiotiques inflig\ue9es par l\u2019environnement. Cet article scientifique explore les d\ue9fis de la s\ue9lection des tomates et identifie les opportunit\ue9s qui peuvent \ueatre explor\ue9es pour am\ue9liorer les initiatives de s\ue9lection des tomates en Afrique. La revue scientifique se concentre sur les principales sources d\u2019information et note que peu d\u2019institutions de s\ue9lection de tomates en Afrique peuvent stimuler une industrie de la tomate dynamique et ses entreprises en aval. Ceci est coupl\ue9 \ue0 des politiques de s\ue9lection inad\ue9quates concernant la lib\ue9ration et la protection vari\ue9tales, les effets n\ue9gatifs du changement climatique, l\u2019\ue9mergence de ravageurs et de maladies qui ont un impact n\ue9gatif sur les efforts de production de tomates en Afrique. Il est possible d\u2019exploiter la diversit\ue9 qui existe actuellement chez les parents de tomates sauvages et d\u2019introduire et de renforcer la s\ue9lection des tomates dans divers instituts de recherche, gr\ue2ce au renforcement des capacit\ue9s. En outre, l\u2019Afrique doit adopter des strat\ue9gies de s\ue9lection \ue0 long terme telles que la pr\ue9-s\ue9lection et l\u2019utilisation de technologies de s\ue9lection modernes, si la production de tomates doit \ueatre maintenue. Les principaux d\ue9fis de production en Afrique comprennent une incidence \ue9lev\ue9e de maladies fongiques et de ravageurs, une faible fertilit\ue9 des sols, une reproduction limit\ue9e des tomates, des stress induits par le changement climatique et le manque d\u2019intrants ad\ue9quats en raison de co\ufbts prohibitifs. Les opportunit\ue9s de production de tomates r\ue9sultent de l\u2019augmentation des populations humaines et par cons\ue9quent de la demande croissante des consommateurs pour la nutrition et l\u2019utilisation potentielle de technologies am\ue9lior\ue9es telles que CRISPR et les technologies de s\ue9quence de g\ue8nes pour produire de nouveaux g\ue9notypes

Evaluation of tomato genotypes for tolerance to major diseases in Uganda

Tomato ( Solanum lycopersicum L.) is a priority vegetable in Uganda, but due to its limited genetic base, its cultivated types are prone to a variety of diseases. The objective of this study was to evaluate new tomato genotypes for resistance to major tomato diseases under hotspot conditions in Uganda. Fourty-five tomato genotypes were evaluated for reactions to tomato bacterial wilt, tomato bacterial speck, early blight and late blight. The study was conducted for two rainy seasons in 2019, at the National Crops Resources Research Institute, Namulonge in Uganda. Data for severity and incidence were collected at two-week intervals after transplanting. Twelve genotypes (Nouvella F1, Rambo F1, Commando F1, AVTO1315, AVTO922, AVTO1701, AVTO1219, AVTO1464, MT56, ADV1287A, Pruna and Vega) exhibited high levels of tolerance to bacterial wilt; while bacterial speck presented mild symptoms majorly seen on Vega, Zodiac and AVTO9802. Rhino, AVTO1418, AVTO1314, Eureka, Roma VFN, MT56, Pinktop, Assila F1, Money-maker, AVTO0922 and AVTO1464 were the least affected by early blight; while AVTO1219, AVTO1701, ADV12021, ADV12076 and ADV1287A expressed low AUDPC values for late blight. Overall, AVTO1315 was the best yielder (30.8 metric tonnes ha-1), followed by AVTO0301 (29.0 t ha-1) and Nouvella F1 (26.1 t ha-1). Among the tomato genotypes evaluated, we recommend AVTO1701, AVTO0922, AVTO1464, AVTO0301 AVTO1315, AVTO1219, Pruna, Vega, ADV1287A and MT56 for the national performance trials.La tomate ( Solanum lycopersicum L.) est un l\ue9gume prioritaire en Ouganda, mais en raison de sa base g\ue9n\ue9tique limit\ue9e, ses types cultiv\ue9s sont sujets \ue0 une vari\ue9t\ue9 de maladies. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer des g\ue9notypes de tomates s\ue9lectionn\ue9s pour leur r\ue9sistance aux principales maladies de la tomate dans des conditions de hotspot en Ouganda. Quarante-cinq g\ue9notypes de tomates ont \ue9t\ue9 \ue9valu\ue9s pour leurs r\ue9actions au fl\ue9trissement bact\ue9rien de la tomate, \ue0 la tache bact\ue9rienne de la tomate, au mildiou et au mildiou. L\u2019\ue9tude a \ue9t\ue9 men\ue9e pendant deux saisons des pluies en 2019, au National Crops Resources Research Institute, \ue0 Namulonge en Ouganda. Les donn\ue9es de gravit\ue9 et d\u2019incidence ont \ue9t\ue9 recueillies \ue0 des intervalles de deux semaines apr\ue8s la transplantation. Douze g\ue9notypes (Nouvella F1, Rambo F1, Commando F1, AVTO1315, AVTO922, AVTO1701, AVTO1219, AVTO1464, MT56, ADV1287A, Pruna et Vega) pr\ue9sentaient des niveaux \ue9lev\ue9s de tol\ue9rance au fl\ue9trissement bact\ue9rien; tandis que la tache bact\ue9rienne pr\ue9sentait des sympt\uf4mes b\ue9nins principalement observ\ue9s sur Vega, Zodiac et AVTO9802. Rhino, AVTO1418, AVTO1314, Eureka, Roma VFN, MT56, Pinktop, Assila F1, Money-maker, AVTO0922 et AVTO1464 ont \ue9t\ue9 les moins touch\ue9s par le mildiou; tandis que AVTO1219, AVTO1701, ADV12021, ADV12076 et ADV1287A ont exprim\ue9 de faibles valeurs AUDPC pour le mildiou. Dans l\u2019ensemble, AVTO1315 a \ue9t\ue9 le meilleur producteur (30,8 tonnes m\ue9triques ha-1), suivi par AVTO0301 (29,0 t ha-1) et Nouvella F1 (26,1 t ha-1). Parmi les g\ue9notypes de tomates \ue9valu\ue9s, nous recommandons AVTO1701, AVTO0922, AVTO1464, AVTO0301 AVTO1315, AVTO1219, Pruna, Vega, ADV1287A et MT56 pour les essais de performance nationaux

Practices and constraints of tomato production among smallholder farmers in Uganda

Tomato (Solanum esculentum) is one of the most promising vegetables whose production is being intensified in Uganda. However, tomato yields remain low due to several constraints. The study aimed at identifying production and marketing practices, and constraints affecting tomato productivity in major tomato growing areas of Uganda. A survey was conducted in eight major tomato producing districts using a questionnaire to guide interviews for 240 farmers and 16 key informants. The data were analyzed using SPSS software. Results revealed that tomato production in Uganda is dominated by males who grow them on 0.68 acres of land on average. Most tomato farmers (78.4%) use mono cropping system with varieties Asilla F1 (35.3%), Tengeru97 (21.1%), Rambo (18.1%), Novela F1 (17.7%) and Riogrande (10.3%) dominating. The choice of tomato varieties used by farmers mainly depend on yield potential, pest and disease tolerance and market preference attributes such as long shelf life. In the study area, tomato is mainly fertilized using foliar fertilizers, followed by Diammonium phosphate and cattle manure. The key pests affecting tomato include caterpillars, thrips, worms and whitefly, while bacterial wilt, blight, leaf spots and viral infections are the major diseases. Majority (95.7%) of farmers use chemical sprays (pesticides and fungicides) and 4.3% of farmers used other control methods. The other methods of pest and disease control included rogueing, hand picking, ash, organic extracts, urine and frequent weeding. Average tomato yield was 4,846.3 kg/acre lower than the potential yield of 6000kg/acre. Thirty five percent of farmers market their tomato individually on-farm, 32.8% sell in rural markets, while 32.2% send to the nearest urban markets. The study revealed intensive chemical use accounting for 20% of the production costs, high seed costs (11%) and drought (10%) as the major production constraints impeding tomato production; and price fluctuations, low prices, high transport costs, post-harvest loss on farm, and poor market access as the major marketing constraints. The research findings will aid in the development of new market-oriented, highly productive tomato varieties with improved access to seed and designing initiatives to address production and marketing constraints, which will eventually enhance tomato production

A review of angular leaf spot resistance in common bean.

Angular leaf spot (ALS), caused by Pseudocer-cospora griseola, is one of the most devastating diseases of common bean (Phaseolus vulgarisL.) in tropical and subtropical production areas. Breeding for ALS resistance is difficult due to the extensive virulence diversity of P. griseolaand the recurrent appearance of new virulent races. Five major loci, Phg-1 to Phg-5, confer-ring ALS resistance have been named, and markers tightly linked to these loci have been reported. Quantitative trait loci (QTLs) have also been described, but the validation of some QTLs is still pending. The Phg-1, Phg-4, and Phg-5loci are from common bean cultivars of the Andean gene pool, whereas Phg-2 and Phg-3are from beans of the Mesoamerican gene pool. The reference genome of common bean and high-throughput sequencing technologies are enabling the development of molecular markers closely linked to the Phg loci, more accurate mapping of the resistance loci, and the compar-ison of their genomic positions. The objective of this report is to provide a comprehensive review of ALS resistance in common bean. Further-more, we are reporting three case studies of ALS resistance breeding in Latin America and Africa. This review will serve as a reference for future resistance mapping studies and as a guide for the selection of resistance loci in breeding programs aiming to develop common bean cultivars with durable ALS resistance

Soil fertility indices of tropical loamy sand as influenced by bambara groundnut variety, plant spacing and fertilizer type

Agricultural sustainability ensues when cultivation of field crops and associated techniques improve not just crop yields but also management-responsive soil properties. Bambara groundnut as an underutilized crop lacks research-based information on its agronomic requirements. This paper reports the key fertility indices of a loamy-sand soil in southeastern Nigeria as influenced by soil and agronomic management practices involving factorial combinations of two bambara groundnut varieties (Caro and Olokoro), two plant spacings (30 cm × 75 cm and 45 cm × 75 cm) and four organic/inorganic fertilizer options. These fertilizer options were NPK 15-15-15 (NPK), single super phosphate (SSP), poultry manure (PM) and Control. The plots under Caro variety spaced 30 cm × 75 cm and grown with NPK or SSP fertilizer showed the highest CEC (8.40 cmol kg–1) and exchangeable K (0.15 cmol kg–1), respectively. Olokoro variety spaced 45 cm × 75 cm and grown with PM or SSP gave the highest total nitrogen (0.14%), soil pHwater (6.35), available phosphorus (107.60 mg kg-1) and exchangeable Ca (3.70 cmol kg-1). The interactions plant spacing × fertilizer type and crop variety × fertilizer type affected all the soil fertility indices studied, while crop variety × plant spacing affected soil pHwater, available phosphorus, CEC and exchangeable Ca and Mg. Generally, as main factors, Olokoro variety, NPK and 45 cm × 75 cm improved soil properties better than their counterparts