POTENTIAL OF NEW TETRAPLOID GERMPLASM IN RUSSIAN WILDRYE

Induced and natural tetraploids have been proposed as promising source s of germplasm in breeding programs to improve Russian wildrye [Psathy rostachys juncea (Fisch,) Nevski], Studies were conducted under semiar id conditions to evaluate the potential of tetraploid (2n=4x=28) Russi an wildrye germplasm recently obtained from Kazakhstan, The tetraploid s had significantly heavier seeds, greater seedling vigor, and they we re significantly taller, and had longer and wider leaves than standard diploid (2n=2x=14) cultivars, Carbon isotope discrimination, which ha s been negatively correlated with water-use efficiency in cool-season grasses, was significantly Power in the tetraploid accessions than the diploid cultivars, Dry matter and seed yield of these unselected tetr aploid accessions were superior to the diploid cultivar Vinall and equ ivalent to more recently developed diploid cultivars, Bozoisky-Select and Syn-A, In general, relative phenological development and forage qu ality of the tetraploid populations did not differ significantly from the diploid cultivars; however, water content, which has been associat ed with greater succulence, was significantly higher in the tetraploid accessions, Significant variation was found among entries within ploi dy levels for most characters indicating that genetic variability is a vailable for additional improvement through selection, Results indicat e that these tetraploid accessions can be used in the development of p romising breeding populations and support earlier conclusions that tet raploid germplasm should receive emphasis in future Russian wildrye br eeding programs.