Identifying drought tolerant short rotation coppice willows

Short rotation coppice (SRC) willows are of interest as they provide a source of renewable carbon for bioenergy and biofuels. One of the major challenges facing future supply of willow biomass is sustaining sufficient yields in drought challenged environments, with research in this area limited to date. The effects of drought responses on Salix germplasm were studied in two pot experiments in a rain out shelter at Rothamsted Research using a split plot design. In both experiments, plants were subjected to two water treatments, drought stressed or well-watered. A temporary water stress was imposed by applying two cycles of drought within a growing season. Experiment 1 aimed to screen 56 diverse Salix genotypes, including subsets of existing genetic mapping populations, to identify potentially informative germplasm
for further study in a more focused second pot experiment. Experiment 2 contained 36 genotypes from two willow full-sibling genetic mapping populations, F and K8. Assessing the potential of mapping population progeny to segregate for
drought traits of interest is an important aim of the study as it offers a potential route to the development of markers for drought tolerance trait selections within the Rothamsted Research willow breeding programme.Phenotypic and final harvest yield measurements were taken on all plants. Primary
results reveal; that pot experiments were effective in producing a useful response to drought stress, that genotypic diversity for drought tolerance exists in Salix, an early drought coinciding with the exponential growth phase has a more negative effect on yield than a drought that occurs later in the growing season, and that top and middle leaf lengths may potentially offer the breeder a high throughput method of assessing the impact of drought on germplasm