Pleiotropic effects of the semi-dwarfing gene uzu in barley

The adoption of reduced height (Rht) genes has dramatically enhanced yield potential of cereal crops. The semi-dwarfing gene uzu in barley is widely used in East Asia. Its value as an Rht gene in the warm and dry environments in Australia was evaluated in this study. In addition to plant height, this gene showed significant effects on a wide range of characteristics. It reduced the overall plant height by an average of 33.7 % with the most significant reduction occurred on the internode below the peduncle. The gene reduces spike length by 31.6 % and grain weight by 18.8 %. It increases grain number per spike by 5.6 % and grain density by 51.8 %. Seedling assays suggested that the effects of this gene became more significant with increased temperature. It reduced coleoptile and seedling length by 19.4 % and 15.1 %, respectively at 7 °C. The reduction increased to 61 % and 46.7 %, respectively, at 25 °C. These results indicated that the uzu gene could have limited values in some high temperature and drought prone environments.