Track 4-1-3: Breeding Range Grasses and Legumes for Biomass and Stress Tolerance
Description
Brachiaria grasses are the most widely planted forages in Tropical America, and their demand is increasing across Africa and South-East Asia. One of the most limiting factors affecting productivity of Brachiaria forage grasses is seasonal drought. Genotypic variation for drought resistance has been found among Brachiaria forage grasses, making possible to genetically improve the productivity of Brachiaria forage grasses under water-limiting conditions (Rao, 2014). The ongoing Brachiaria breeding program at the International Center for Tropical Agriculture (CIAT) has been developing and testing Brachiaria hybrids that combine resistance to biotic constraints with adaptation to abiotic stresses such as drought.
Adaptation to drought conditions greatly relies on an efficient root system that facilitates water capture in drying soil. Among root traits, greater root length density (the length of roots per unit volume of soil, RLD cm/cm3) generally indicates greater ability for water uptake in drying soil (Wasson et al., 2012). Screening of forage germplasm for resistance to drought conditions has often overlooked root traits. This is because of the difficulty to separate roots out of soil, which inevitably ends up in a very low-through-put system. However, new imaging techniques allow rapid estimation and quantification of RLD within the soil (i.e., without the need to separate roots from soil). The following work was therefore performed to evaluate the variation in dry mass, water uptake and RLD of 103 hybrids of Brachiaria after three weeks of growth under drought conditions. We hypothesized that hybrids with greater RLD could extract (particularly with increasing depth) more water in drying soil, which in turn is reflected in greater shoot dry mass production after three weeks of drought treatment.
Included in
Brachiaria Hybrids with Larger Root Length Densities Show Greater Shoot Vigor under Drought
Brachiaria grasses are the most widely planted forages in Tropical America, and their demand is increasing across Africa and South-East Asia. One of the most limiting factors affecting productivity of Brachiaria forage grasses is seasonal drought. Genotypic variation for drought resistance has been found among Brachiaria forage grasses, making possible to genetically improve the productivity of Brachiaria forage grasses under water-limiting conditions (Rao, 2014). The ongoing Brachiaria breeding program at the International Center for Tropical Agriculture (CIAT) has been developing and testing Brachiaria hybrids that combine resistance to biotic constraints with adaptation to abiotic stresses such as drought.
Adaptation to drought conditions greatly relies on an efficient root system that facilitates water capture in drying soil. Among root traits, greater root length density (the length of roots per unit volume of soil, RLD cm/cm3) generally indicates greater ability for water uptake in drying soil (Wasson et al., 2012). Screening of forage germplasm for resistance to drought conditions has often overlooked root traits. This is because of the difficulty to separate roots out of soil, which inevitably ends up in a very low-through-put system. However, new imaging techniques allow rapid estimation and quantification of RLD within the soil (i.e., without the need to separate roots from soil). The following work was therefore performed to evaluate the variation in dry mass, water uptake and RLD of 103 hybrids of Brachiaria after three weeks of growth under drought conditions. We hypothesized that hybrids with greater RLD could extract (particularly with increasing depth) more water in drying soil, which in turn is reflected in greater shoot dry mass production after three weeks of drought treatment.
