Genotypic responses of Brachiaria Grass (Brachiaria spp.) accessions to drought stress

Abstract

Background and O bjective: Brachiaria, a warm season C4 grass, is rapidly gaining popularity as fodder crop in Africa where it is also used as a component of a habitat management strategy for maize stem borers. However, increasing drought limits productivity of this grass species. The aim of this study was to evaluate and select high yielding brachiaria genotypes under simulated drought condition s. Materials and Methods: The morphological and physiological performance of 18 apomictic accessions of brachiaria in simulated drought conditions in a screen house were evaluated. Plants were expose d to different watering regimes. Well-watered (control) plants were watered every 48 h to 100% field capacity while drought was sim ulated by suspending watering for 14 and 28 days, representing moderate and severe drought conditions, respectively. Shoot len gth, leaf length and width, number of tillers, leaf relative wa ter content, chlorophyll content and above ground biomass were studied. Result: Water stress had negative effects on the morphological and physiological traits, with the effects being more pronounced un der severe drought stress. Based on the drought stress index (D SI) values for the measured parameters and Principal Component of Analysis (PCA) biplots, the following accessions were least affected under severe drought stress: ‘Xaraes’, ‘Piata’, ‘Marandu’, ‘CIAT 679’, ‘Mulato II’ and ‘Mulato I’. Conclusion: Under increasing drought conditions, biomass yield was an accurate predictor of drought tolerance of the gen otypes. ‘Piata’ and ‘Xaraes’ combined both drought tolerance an d biomass yield. These two accessions were proposed as of value in improv ement of the sustainability of cereal-livestock farming systems under conditions of increasing aridification.