The breeding method for seeded type variety of Zoysia grass was investigated. Zoysia grass is known to propagate by selfing, outcrossing and vegetative cloning. Some of the lines examined produced more than 50,000 grains and over 150 g of germinative seeds per 1 m2 by selfing. Furthermore, it was possible to select the selfed lines in which the segregation rate was small and where there were small degrees of the inbreeding depression as a result of comparison with the leading variety and self-propagation progeny. In the first year, dozens of high seed production individuals were selected from many ecotypes and preservation stocks. These individuals were bagged and produced 50–100 selfed seeds. The selfed lines were examined, and several elite lines showing favorable characteristics, less segregation and without apparent inbreeding depression were selected. Parental clones of the selected lines produced selfed seeds by the isolated culture. These selfed lines were compared again for characteristics, segregation and inbreeding depression in both broadcasting and space planting fields, and the best line was selected. Finally, mass seeds of the seeded type new line could be produced in the seed production field made by vegetative propagation of an elite parental clone. These results suggest that this method can be effectively utilized for the breeding in seeded type variety of Zoysia grass.
Effect of nitrogen fertilizer on seasonal yield of Zoysia japonica and Eremochloa ophiuroides. Aannual dry matter production of Z. japonica and E. ophiuroides ranged between 752.8–947.0 g/m2 and 531.4–774.1 g/m2, respectively. Annual dry matter production of both grasses significantly increased by applying 12 g/m2 a year comparing to 0 and 6 g/m2. Z. japonica showed relatively higher yields than E. ophiuroides at most of the assessment date. Changes of LAI indicated that threshold of monthly mean air temperature to green is 10.1 to 12.3ºC and 12.3 to 16.8ºC respectively. Z. japonica has higher tiller density than E. ophiuroides in early spring, and Z. japonica may be better. The result showed Z. japonica provides steady and higher yields and better as grassland, too.