Water stress and water use efficiency of ten white clover cultivars

Abstract

Ten cultivars of white clover were grown in a glasshouse at three levels of soil moisture. Leaf productivity was greatly reduced by moisture stress. The productivity of cultivars was found to be significantly different under well-watered conditions. Larger-leaved cultivars tended to be more productive than those with smaller leaves, but this difference was lost at high moisture stress creating a significant cultivar by moisture treatment interaction. Water use efficiency (WUE) increased with increasing moisture stress, but within any one moisture level there were no significant differences between the cultivars. An integrated measure of WUE is captured by the level of discrimination against 13C in plants tissue (Ä). Over the range of moisture levels used, a strong negative correlation was found between Ä and WUE. A strong positive correlation was found between productivity and Ä over the range of moisture treatments, however, within any one moisture level no significant relationship was established. Keywords: carbon isotope discrimination, cultivars, moisture stress, Trifolium repens, water use efficiency