Germination models were developed in a growth chamber study for four cool season grasses; Kentucky bluegrass, chewing fescue, tall fescue, and perennial ryegrass. These models were applied to a field study where air and soil surface temperatures were measured. Both air and soil surface temperature models better predicted growth in fast-germinating species. Perennial ryegrass, which had the fastest germination of all species, germinated on the day predicted by the air temperature model. Estimates from the air temperature models tended to be a few days earlier than those from the soil surface temperature models; however, the estimates were considered to be similar. Due to the fact, for ease of use we recommend using the air temperature models.

In order to examine the effects of a pod on a seasonal prevalence, emergence depth, and viability of seed in Kudzu (Pueraria lobata (Willd.) Ohwi), pot tests were conducted under field conditions from Feb. 21, 2013 to Oct. 28, 2013 in Utsunomiya, Japan. The results obtained from the study were summarized as follows. When the seeds and the pods were placed at 0 cm (soil surface), 2.5 cm, 5.0 cm and 10.0 cm depth of soil and then the number of emerged plants were counted at 1 month intervals for 8 months, the cumulative number of emerged plants were 2.5 cm>5.0 cm>0 cm>10 cm plots and no emergence was observed at 10 cm plot in both seed and pod plots. At 2.5 cm depth where a large number of seedlings emerged, the emergence was concentrated in Apr. for the seed plots, however, the emergence was dispersed from Apr. to Aug. for the pod plots. Moreover, seed viability was confirmed 8 months after sowing regardless of the burial depth of the seed or the pod. These results suggest that the pod does not affect the emergence depth and the seed viability, but extend the germination period of seed in Kudzu.