Hybrids of ryegrasses and meadow fescue and their value for grass breeding

Abstract

1. In attempts to intercross Lolium perenne and L. multiflorum with Festuca pratensis in a glasshouse, 13,284 emasculated flowers of diploid, triploid and tetraploid Lolium plants were provided with pollen of diploid and tetraploid Festuca plants. Only the combinations 2n\sx4n and 3n\sx4n produced hybrids, viz. on average 5.3 and 1.0 mature hybrid plants per 100 pollinated flowers. In crosses performed in winter these averages were 12.0 and 4.9 respectively. 2. Non-emasculated spikes of diploid, triploid and tetraploid plants of L. perenne and L. multiflorum in the field were enclosed in pergamine bags with panicles of diploid, triploid and tetraploid plants of F. pratensis. Apart from the above-mentioned combinations hybrids were also obtained of the crosses 2n\sx2n and 2n\sx3n. The number of hybrids produced per inflorescence was on average nearly as high as in corresponding crosses in the glasshouse. By bagging together spikes of self-incompatible diploid plants of L. perenne and L. multiflorum with panicles of tetraploid plants of F. pratensis in the field, large numbers of triploid hybrid seeds may easily be obtained. This opens the possibility of using seed treatment with colchicine for the production of hexaploids. 3. Triploid hybrids showed a better production in spring and a better aftermath growth in summer than either parent plants. Spontaneously obtained hybrids were more winterhardy than most winterhardy indigenous types of perennial ryegrass. 4. All artificial and most natural hybrids had no dehiscent anthers; the percentage of normal pollen varied in the artificial hybrids from 0 to 3.8%, in the natural hybrids from 0 to 10%. Several plants in both groups were slightly female fertile. Some plants with hybrid characters, collected from natural grassland, had dehiscent anthers and more than 75% stainable pollen; their female fertility was fairly good. 5. Open pollinated seeds of triploid male sterile hybrids produced, apart from a majority of plants closely resembling the parent species, or the F1 hybrids, also types with new combinations of characters. The male fertility was considerably higher than in the previous generation: several plants had dehiscent anthers. In spontaneous families of the male fertile hybrid forms greatly deviating types of Lolium occurred. 6. Some possibilities of the various cross combinations for the breeding of ryegrasses are discussed.