M. Mahadevan, Pamela K. Zwer, Victor O. Sadras
South Australian Research and Development Institute, Urrbrae, SA 5064 email@example.com
We measured yield of 29 oat lines in nine environments returning a range from 0.3 to 4.2 t ha-1. Other traits were measured in 4-7 environments. Environment, genotype and their interaction affected all traits (P<0.0001); ANOVA was thus largely uninformative. To account for these interactions, we used a plasticity framework showing three types of trait-dependent responses. For grain number and its components, plant height, harvest index, WSC and N at two stages (GS71 and maturity), high plasticity was associated with the ability to capture favourable conditions (90th percentile) and little variation under stress (10th percentile). For biomass at both GS71 and maturity, high plasticity was associated with a trade-off between capacity to capture favourable conditions and growth under stress. For seed size, high plasticity was associated with low seed weight under stress. Yield was closely related to grain number and weakly associated with grain weight. Grain number was negatively related to water soluble carbohydrates at GS71 and maturity, which were in turn negatively related to shoot N concentration. Under favourable conditions, some varieties maintained a high concentration (> 20%) of water soluble carbohydrates at harvest maturity. Selection against this trait could improve yield potential, but residual labile carbohydrates can also be exploited in dual grain-feed varieties, and can provide flexibility for hay growers when logistics preclude cutting at the common water ripe (GS71) target.