‘Palbangmi’ is a super high-yield rice cultivar bred by interspecies cross between Tongil type and Africa rice. But, ‘Palbangmi’ has a problem in grain maturation which results in rice yield decreases. Because ‘Palbangmi’ is Tongil and Africa rice interspecies-crossed cultivar, it would be predicted to require higher temperature for grain maturation than japonica rice. Therefore, ‘Palbangmi’ would be required to determine Late Marginal Heading Date (LMHD) for normal maturation. In this study, experiment of transplanting date was carried out to determine LMHD of ‘Palbangmi’ in Suwon and Iksan for 3 years. When daily mean temperature was below 23oC, grain filling ratio (%) increased about 8% for each 1oC. On the other hands, grain filling ratio (%) didn't increase when the daily mean temperature was above 23oC. Therefore, it is determined that 23oC is adequate for minimum threshold temperature for grain maturation. The LMHD of ‘Palbangmi’ was determined from calculated heading dates for each year which could satisfy threshold temperature for 40 days after heading during last 15 years. As a results, LMHD was earlier than August 1 in 16 regions where it is inadequate for ‘Palbangmi’. Continually, LMHD was August 1 ~ August 5 in 13 regions, August 6 ~ August 10 in 14 regions and August 11 ~ August 15 in 21 regions. Finally, LMHD was later than August 15 in 14 regions. Considering that heading date of ‘Palbangmi’ is August 13 as mid maturing ecotype, it is suggested that earlier transplanting required for normal maturing in almost areas except south plain area and some areas of central plain area.

A double-cropping system with soybean (Glycine max) following the cultivation of potato, garlic, and onion is widely adopted in the southern region of Korea. For this system, marginal dates for planting must be determined for profitable soybean yields, because the decision to plant soybean as a second crop is occasionally delayed by harvest of the first crop and weather conditions. In order to investigate the effect of planting date on soybean yield, three cultivars (early and late maturity) were planted on seven different dates from May 1 to July 30 in both paddy and upland fields across 2012 and 2013. Soybean yields were significantly different among the planting dates and the cultivars; however, the interaction between cultivar and planting date was not significant. Based on linear regression, the maximum yield of soybean was reached with a June 10 planting date, with a sharp decline in yield for crops planted after this date. The results of this study were consistent with those of a previous one that recommends early and mid-June as the optimum planting period. Regardless of soybean ecotype, a reduction in yield of greater than 20% occurred when soybean was planted after mid-July. Frost during soybean growth can reduce yields, and the late maturity cultivars planted on July 30 were damaged by frost before completing maturation and harvest; however, early maturity cultivars were safely harvested. For sufficient time to develop and reach profitable yields, the planting of soybean before mid-July is recommended.