ABSTRACT
Summary Kentucky bluegrass (Poa pratensis L.) has been hybridized with many other Poa species, but interspecific hybrids between fowl bluegrass (P. palustris L.) have not been reported so far. In contrast to most other Poa species, P. palustris, like P. pratensis, is a commercially used forage crop, and we expected better results in such hybrids than in those described earlier. The obligate apomict P. palustris was X-irridiated, and two-seed-descendant X2 plants were grown in the nursery. A total of 47 pairs with different partners were selected and checked for sexuality. One plant with a segregating progeny was used for hybridization. Flowering time of the two Poa species differed by about one month. This difficulty was overcome by storage of the P. pratensis pollen at a temperature of - 80°C. Hybridization was done without emasculation on single plants in isolation chambers. Among the progeny of 200 plants, we found up to 27 hybrids with P. pratensis, the remainder being pure P. palustris. In 1972, the first recorded hybrid plants were pure apomicts and stable in multiplication, the interspecific heterosis being fixed in the evolved strains. One strain is a pasture-and-lawn type, another a meadow type. Both strains have the subterranean runners of P. pratensis and the leaf color of P. palustris. One strain has hairless seeds like the P. palustris parent. Disease resistance and yield quality of these strains are much better than those of P. longifolia x P. pratensis interspecific crosses. One of the new hybrids looks so promising that it is under registration proceedings in West Germany.
