Tomato (Solanum lycopersicum) productivity is negatively impacted by extreme weather events such as heatwaves, flooding and drought. This study evaluated the individual and additive effects of heat and water stress on reproductive traits and yield in the commercial tomato variety 'Roma-VF'. Five weeks after sowing, five stress treatments were introduced consisting of combinations of heat and/or moderate and severe water stress. Heat-stressed plants were subjected to day/night temperatures of 35/23°C, and the control of 28/20°C. Moisture stress was imposed by natural depletion of soil water to 70% and 40% of field capacity (moderate and severe stress, respectively). After eight weeks of treatments, plants were placed under control conditions for a five-week recovery phase. Pollen morphology, number of flowers, fruits, and aerial biomass were recorded. Flowers from plants subjected to heat stress combined with either moderate or severe moisture stress did not produce any pollen during the treatment period. Further, by the end of the recovery period, 27-38% fewer fruits matured on plants subjected to either heat or moisture stress, while fruit production among plants subjected to both stresses simultaneously declined 90% relative to the control (P < 0.001). We conclude that the 'Roma-VF' tomato will be able to recover adequately from heatwaves provided plants are well irrigated. However, should heat and moisture stress co-occur, fruit yield is likely to be decimated and recovery is unlikely. This study is also the first report on additively combined effects of heat and water stress on the 'Roma-VF' tomato.

Abstract:The relative susceptibility of different accessions of Bambara groundnut (Vigna subterranean L. Verdc) to Callosobruchus maculatus (F.) was assessed in a laboratory trial in Nigeria. Treatments were comprised factorial combinations of four grain sources from Nigeria (Enugu, Anambra, Benue and Kogi state) and three predominantly contrasting seed coat colours (black, brown, and milky-colour) laid out in a completely randomized design (CRD). There were four replications of each treatment. Egg depositions by adult C. maculatus were affected by grain sources such that ovipositions on those sourced from the state of Anambra were significantly (p < 0.05) higher than those from other sources. Similarly, black coloured grains harboured more insects and eggs compared to other seed coat colours. Accesssions collected from Benue and/or those with a milky-coloured seed coat showed some levels of oviposition deterrence. However, the interaction of grain source and seed coat colour was not significant based on oviposition, adult emergence, and mortality counts. Grain sources and seed coat colour were, therefore, important traits to be considered while selecting ideotypes for resistance to C. maculatus.

Within West Africa (WA), poverty, population growth rate and food insecurity are high and most agriculture is conducted at an un-mechanised level, reliant on rain-fed conditions. As with elsewhere around the world, there is a clear fingerprint of climate change on WA, with increasing temperatures and shifts in precipitation patterns. As the century progresses and climate change intensifies, so too will the impact on rain-fed horticulture. This creates an urgent need to understand and synthesis the responses of horticultural crops to climate change and identify adaptation options. This review provides an overview of climate change across WA and the impacts on key horticultural crop groups (vegetables, plantations, fruits and root and tubers) and identifies regions within WA where these crops may be more or less vulnerable to changing conditions. Adaptation actions and strategies- ranging from education, introduction of new cultivars and development of effective cropping systems, to transference of skills from other regions and expansion of farmer-government-NGO collaborations are discussed.

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