Theme 13: Plant Improvement
Description
Hybrids between the stolonifeous white clover (Trifolium repens L., 2n=4x=32) and rhizomatous Caucasian clover (T. ambiguum M.Bieb, 2n=4x=32) have been produced. A backcross 2 (BC2) generation with white clover as the recurrent parent combines the growth habit of both parent species with the objective of increasing the persistency of large leaved T. repens varieties under grazing. T. ambiguum is more drought tolerant than T. repens. The drought tolerance of the hybrids in comparison with the parental species was compared in deep soil bins over a four week drought cycle. Soil moisture content, leaf relative water content (RWC), and leaf water potential were measured on plants subjected to drought and those watered normally and maintained at field capacity. T. ambiguum and the backcross hybrids were able to maintain a higher leaf RWC and leaf water potential than T. repens at comparable levels of soil moisture. The dry matter production of the hybrids and parental species was also compared in field plots sown with a perennial ryegrass companion. In the first harvest year, under a cutting regime, the yield of T. repens was highest and T. ambiguum lowest with the hybrids intermediate between the parents, with the BC2 approaching the yield of T. repens. These hybrids will be evaluated over further years and under grazing. The implications of these results for T. repens germplasm improvement programmes are discussed.
Included in
Drought Tolerance of Interspecific Hybrids between Trifolium repens and Trifolium ambiguum
Hybrids between the stolonifeous white clover (Trifolium repens L., 2n=4x=32) and rhizomatous Caucasian clover (T. ambiguum M.Bieb, 2n=4x=32) have been produced. A backcross 2 (BC2) generation with white clover as the recurrent parent combines the growth habit of both parent species with the objective of increasing the persistency of large leaved T. repens varieties under grazing. T. ambiguum is more drought tolerant than T. repens. The drought tolerance of the hybrids in comparison with the parental species was compared in deep soil bins over a four week drought cycle. Soil moisture content, leaf relative water content (RWC), and leaf water potential were measured on plants subjected to drought and those watered normally and maintained at field capacity. T. ambiguum and the backcross hybrids were able to maintain a higher leaf RWC and leaf water potential than T. repens at comparable levels of soil moisture. The dry matter production of the hybrids and parental species was also compared in field plots sown with a perennial ryegrass companion. In the first harvest year, under a cutting regime, the yield of T. repens was highest and T. ambiguum lowest with the hybrids intermediate between the parents, with the BC2 approaching the yield of T. repens. These hybrids will be evaluated over further years and under grazing. The implications of these results for T. repens germplasm improvement programmes are discussed.
