Report on adjusting a high throughput screening tool to support water use phenotyping in forages

Drought severely limits forage productivity. The avoidance of water deficit by increasing the capacity for water uptake or by controlling water loss are common responses. A fine interplay exists between the acquisition of water by roots in drying soil and water loss through transpiration. These two components tend to act simultaneously. The following approach and aim is therefore to provide information of shoot development, root development and water use over time of plants growing under greenhouse conditions with soil from target sites. Greenhouse studies is a vital part of phenotyping for drought conditions as allow the recording of responses that would be otherwise impossible under filed conditions

Genotypic variation in drought resistance among Urochloa Hybrids (population Br15)

Previous research showed a correlation in the ability to uptake water from drying soil and shoot biomass production in Urochloa hybrids (Jimenez et al, 2016). The ability to uptake water in drying soil is associated with a larger and deeper root system in Urochloa grasses (Cardoso et al., 2015). Bearing that into mind, drought resistance in Urochloa grasses has been defined as the ability to produce more biomass under water-limiting conditions. Due to improvements in off-the-shelf imaging sensors and image analyses, routine estimation of visible total root length and deep rooting (root length at depth below 60cm of soil surface) is now a reality (Cardoso and Rao, 2019). However, such estimations are not straightforward. Maximum rooting depth (i.e., length of the longest visible root) holds promise for its use as a proxy for deep rooting. The following work aimed to evaluate the variation in dry mass, water uptake, maximum rooting depth, deep rooting and total root length of 84 hybrids of Urochloa hybrids after three weeks of growth under well-watered and water-limiting conditions. We hypothesized that hybrids with larger and deeper roots systems could extract more water in drying soil which in turn is reflected in greater shoot dry mass production. We also hypothesized that maximum rooting depth could be used as a surrogate measurement of deep rooting. Pearson correlation, simple and multiple linear regressions were calculated to test the relationship between individual and combination of root traits upon shoot biomass. Broad sense heritability was calculated for each trait and watering to test their relevance and suitability for screening purposes

Evaluation and selection of forage materials water stress

Having few improved forage options puts the livestock sector at risk of low productivity in the event of extreme abiotic stress events ( eg , droughts, floods). Currently, the CIAT genebank (now Alianza Bioversity -International-CIAT) and ILRI (International Livestock Research Institute) has the largest and most diverse collection of tropical forages in the world. This diversity of germplasm allows the selection of new materials with potential for adoption in different agroecological conditions in Colombia. Information related to the existing diversity in tropical forages in terms of their resistance to drought and tolerance to waterlogging can serve to improve animal production in periods of drought and extreme rainfall. Additionally, knowledge of the development of different pastures and their water demands can better recommend the most appropriate genotypes for various climates and situations, and guide grazing management and irrigation schedules