Agriculture, Ecosystems and Environment 268, 79-89. DOI: https://doi.org/10.1016/j.agee.2018.09.006
Abstract: The 2015/2016El Niño was the most severe on record in southern Africa and was associated with drought and heat stress. To help farmers to cope with such extreme production constraints the International Maize and Wheat Improvement Centre (CIMMYT), has been developing multiple stress tolerant maize varieties through a rapid-cycle breeding strategy. These CIMMYT stress tolerant maize hybrids were evaluated using two types of trials. The first one comprised a regional on-farm trial with forty maize varieties (20 early-intermediate and 20 intermediate-late varieties), planted across 30 locations in four countries in southern Africa. The second set comprised a multi-locational evaluation trial with six hybrids that were tested under conventional ridge tillage (CP) and conservation agriculture (CA) using a randomized block design with each farm as replicate in nine extension planning areas (EPA), across two years. CIMMYT stress tolerant varieties outperformed non stress tolerant varieties. CZH142020 (5.6 t ha −1) and CZH131008 (4.8 t ha −1) had significantly higher yield advantage over commercial control varieties (<4.5 t ha −1) in both early and late maturity groups. They also had larger grains and smaller ear uniformity index (EUI) (calculated as among plots ear size variance); compared non-stress tolerant varieties. In the CA/CP evaluation trial, varieties under CA yielded ≥0.7 t ha-1 more grain compared to those under CP. Therefore, combinations of climate-smart agriculture technologies are required to mitigate negative effects of extreme events like El Niño and increase resilience of low-input farming systems.