John MacRobert

Adapting maize production to climate change in sub-Saharan Africa

Given the accumulating evidence of climate change in sub-Saharan Africa, there is an urgent need to develop more climate resilient maize systems. Adaptation strategies to climate change in maize systems in sub-Saharan Africa are likely to include improved germplasm with tolerance to drought and heat stress and improved management practices. Adapting maize systems to future climates requires the ability to accurately predict future climate scenarios in order to determine agricultural responses to climate change and set priorities for adaptation strategies. Here we review the projected climate change scenarios for Africa’s maize growing regions using the outputs of 19 global climate models. By 2050, air temperatures are expected to increase throughout maize mega- environments within sub-Saharan Africa by an average of 2.1°C. Rainfall changes during the maize growing season varied with location. Given the time lag between the development of improved cultivars until the seed is in the hands of farmers and adoption of new management practices, there is an urgent need to prioritise research strategies on climate change resilient germplasm development to offset the predicted yield declines.

Political and economic features of the maize seed industry in southern Africa

ABSTRACT The seed industry in southern Africa (Angola, Malawi, Mozambique, Zambia and Zimbabwe) has three important features: first, dominance of the government as buyer and distributor of seed; second, a high market share and power of few seed companies; and third, a sustained but incomplete effort to harmonize the seed policy in the region. The challenges the seed industry is facing are lack of basic seed, poor production infrastructure, lack of skill in seed production, challenges to access and multiply seeds of varieties released from public institutions, lack of purchasing power among smallholder farmers, high transaction cost of seed marketing, market-distorting interventions by governments, lack and misuse of market information, free riding, lack of working capital financing, and breaching of contract by seed growers. Important policy implications have been drawn from this study, which include strengthening national research systems, strategic capacity building along the maize seed value chain, improving the access to financial services, developing and implementation of agreed protocols of SADC for seed policy harmonization.

Diallel analysis of acid soil tolerant and susceptible maize inbred lines for grain yield under acid and non-acid soil conditions

Maize is not inherently tolerant to soil acidity but due to the ever increasing demand for the crop in the developing world, production of maize on acid soils continues to expand. Breeding for maize acid soil tolerance is the best strategy to improve yield under these conditions. Therefore, the current study was done to determine the general combining ability (GCA) of eight acid-soil tolerant and susceptible inbred lines and the specific combining ability (SCA) of cross combinations of these lines for grain yield under acid and non-acid soils. The eight lines were crossed using a diallel mating design to produce 28 single cross hybrids for evaluation under acid and non-acid soils at four sites for two seasons. Line C2 was the best general combiner under both soil environments while A2/C1 and A1/C2 had the highest desirable SCA effects under optimal conditions. Loss in grain yield and sensitivity to low pH stress was higher among genotypes in light textured soils than heavy soils. Non-additive gene action was more important than additive gene action in conditioning grain yield under both environments. Results revealed that it was feasible to improve grain yield under low pH and optimum soils from the set of genotypes used in the current study.