Overwintering capacity, closely related to winter hardiness, of Chinese milk vetch planted with different sowing times and sowing practices was investigated to improve the incorporation into cropping system in Korea. The tolerance to low temperature was evaluated with LT50 using leaf disc leaching method. Dry weight of CMV was reduced remarkably with delayed planting from Sep. 5 to Oct. 20. The differences in tolerance to freezing temperature were not conspicuous among CMV genotypes, however, the differences between genotype (collections at different regions) were due to the plant architecture, mainly to the leaf angle. The crouching genotype collected at central region of Korean peninsula, which showed excellent freezing tolerant, has planophile leaves. The feature of internal constituents of CMV genotypes did not show any noticeable differences with respect to the freezing tolerance which evaluated by leaf disc leaching experiment. To overcome the poor overwintering capacity, tolerant genotype should be developed by selection with considering the plant architecture. The reduction of CMV growth during overwintering period was ameliorated with furrow-sowing under late-sown condition, therefore, when the CMV is inevitably sown late after recommended time, the seeds should be sown on furrow to overcome the cold stress.

Germination and emergence habits of Chinese milk vetch (CMV) were examined to obtain the basic information for the effect of environmental conditions and cultural practices on the seedling density. Seed germination tests with different water potentials, temperatures, and soil and water depths showed the environmental effects on the characters related to seed germination in CMV. Imbibition under different temperatures reflects that initial velocity was rapid at higher temperature, however, the times to full imbibition were not different between 15 and 25~circ . The optimal germination temperature for CMV germination was ranged from 15 to 20 and the germination was highly affected by water potential of media at relatively high temperature above 20~circ . When the seeds were sown in flooded condition the germination was not proportionally affected by water depth. In addition, there was no correlation between water depth and oxygen concentration. The germination of seeds flooded by 2cm water depth were poorly germinated compared to other depths. Results indicated that the germination of submerged seeds was more highly influenced by flooding depth than the temperature, it was also affected more strongly at 10 than 20~circ . Emergence of CMV depending on the thickness of covered soil was poor when the soil layer was greater than 5cm. In the experiment with seeds collected between 22 days after flowering (OAF) and 52 DAF, the highest germination ability of CMV seeds was observed at 39 DAF and germinability was decreased subsequently as seeds became mature. The lower germinability may be due to the enhanced seed dormancy.

An experiment was carried out using pots to investigate the effects of Chinese milk vetch on the seedling establishment and growth in rice. Four irrigations with five-day intervals and three different levels of vetch straw were investigated. Significantly higher panicle numbers were obtained in vetch-treated pots. Vetch levels were non-treatment as checks, vetch with top removed, root plus shoot 7.5 ton/ha, and root plus shoot 3.0 ton/ha. The time for complete degradation of vetch straws was reduced from 10 days to 5 days as submerged time was delayed, and was affected by the amount of mulched vetch straws. As the mulched vetch amount increased, the time for a complete degradation was extended from 4 days to 12 days. Grain yield and its components were significantly affected by irrigation time and mulched vetch amount. Effectively controlled, lowered reduction damage from the degrading vetch straw, irrigation date and vetch amount were the most important factors for the improving of seedling establishment in direct-sown rice.

This study was carried out to determine the effects on rice growth, yields and soil improvement under the different nitrogen levels in machine-transplanted rice after plowing at the fruiting stage of milk vetch. The fresh weight of milk vetch at plowing time was 20.95 ton/ha. In dry weight, T-N and C/N were 1.58%, 21.8%, respectively. Organic matter, total nitrogen and exchangeable calcium of soil after the experiment in the plot of milk vetch were higher than those before the experiment. Leaf area and dry weight of rice plants at heading date increased as nitrogen level increased. The number of panicle and spikelets per ~textrmm2 were not different except for the 110 kg/ha nitrogen level plot with milk vetch. Brown rice yield ranged from 5.45 to 6.08 ton/ha, in creasing with increased nitrogen level. So the yield increased by 1% at 77 kg/ha nitrogen level, 7% at 110 kg/ha nitrogen level plot with milk vetch compared with conventional level (rice straw 5.4 ton/ha and nitrogen 110 kg/ha).