Abstract
We assessed winter survival for three varieties of rhodesgrass (Chloris gayana Kunth) at three different sites and seasonal productivity at one site to identify rhodes-grass varieties that can survive winters and be productive in the growing season. Three varieties of "Asatsuyu", "Katambora" and "Hatsunatsu" were sown in early May 1999, 2000 and 2001 to determine the dry matter yield by 4-5 cuttings in the growing season and winter survival at the Nagasaki Prefectural Livestock Experiment Station. Winter survival rates of "Asatsuyu" and "Katambora" were evaluated in two consecutive winters in Miyazaki, Miyazaki Prefecture and Fukue island, Nagasaki Prefecture. In the summer period of low solar radiation, the dry matter yield was higher in "Asatsuyu" than in "Katambora". The dry matter yields at the final cuttings in autumns in 1999 and 2000 tended to be higher in "Asatsuyu" than for the remaining two varieties, suggesting that "Asatsuyu" grows more rapidly under low temperatures. Winter survival was higher in "Asatsuyu" than in "Katambora". This high rate is related with a larger stubble size of "Asatsuyu" before winter and its higher amount of non-structural carbohydrate in subterranean stems in winter. As the plants were cut earlier before winter, winter survival tended to be higher in Rhodesgrass. Winter survival and dry matter yield at the first cutting in the next early summer were higher in "Asatsuyu" than in "Katambora", both in Miyazaki and Fukue island. These results revealed that "Asatsuyu" is highest in winter survival and dry matter productivity among examined varieties, suggested that "Asatsuyu" is the most suitable variety of Rhodesgrass in the light-frosted areas of the south-western warm regions of Japan.
