Drought caused by global climate change is one of serious problems for rice cultivation. However, it was little reported the impact of drought on rice cultivation in Korea. In here, to assess impact of drought on rice varieties in Korean climate condition, growth characteristics and yield components of rice were compared on irrigated and partially irrigated rice paddy field. First, we have chosen 11 rice varieties including ‘Saeilmi’ and ‘Shindongjin’ which are widely cultivated in Korea. For partially irrigated rice paddy treatment, we have withheld irrigation from 25 days after transplanting and water supply was totally dependent on rainfall for rice cultivation. When we examined early plant height and tiller number of these varieties on partially irrigated rice paddy were reduced 1.6% to 18.4% and 10.4% to 33.1%, respectively, and these reduction rate were highly correlated with yield loss in our experimental conditions. Among rice yield components, panicle number was decreased 10.5% to 30.1% according to rice varieties and reduced panicle number was highly correlated with yield loss. Grain number per panicle, grain filling rate and 1,000 seeds weight did not have correlation with yield loss of rice varieties. These result means that growth stage, especially the tillering stage, is seriously affected by drought on rice cultivation in Korea. And we suggest that ‘Saeilmi’, ‘Ilmi’ and ‘Ilpum’ are good for rice cultivation on drought prone rice field in Korea.

In here, we screened drought tolerant varieties with modified leaf water loss rate assay and visual drought tolerant phenotype in the greenhouse conditions with more than 800 varieties. Among these varieties, Samgang, Gumei4 and Apo showed the lowest of leaf water loss rate and strong drought tolerant phenotype. To identify drought QTLs with Samgang variety, we developed the doubled-haploid (DH) population consist of 101 lines derived from a cross the drought tolerant cultivar Samgang and the drought sensitive cultivar Nagdong. To score the drought phenotype degrees of this population, we withheld water for 6 weeks and treated the watering for 7 days. After watering, visual phenotype was observed 1 to 9 degree according to the standard evaluation system for rice, IRRI. Drought sensitive parent Nagdong was almost died and was scored as 9 degree, while tolerant parent Samgang showed slightly leaf tip drying phenotype and was scored as 3 degree in our experimental conditions. Three main QTLs were detected on chromosome 2, 6, and 11 with this visual phenotype. We also measured relative water contend of these population under drought stress conditions, and got one main QTL on chromosome 11. The QTL loci on chromosome 11 with flanking markers RM26755-RM287 has a function for visual phenotype and relative water content under drought conditions.

Rice is a staple food crop for more than half of the world population. Severe losses of rice production was caused by various environmental conditions such as cold, heat and flooding annually. Rice is a highly sensitive to low temperature below 15-20 ℃ because of originating from tropical or subtropical climates. Especially, seedling of rice is easily damaged to low temperature and result in seedling yellowing, growth retardation, reduced tillering and yield losses at last. We used a recombinant inbreeding lines (RIL) population of 384 individuals derived from a cross between Hanareum 2, a highly cold sensitive variety and Unkwang, a cold tolerant variety for molecular mapping of QTLs related to cold tolerance. Seedling discoloration of each lines and parents caused by cold response were investigated in field condition after transplanting. And leaf samples of RIL population were collected for evaluation of chlorophyll content using 80% acetone extraction. The seedling of each lines and parents was subjected to low temperate by 5~13 ℃ during 14 days. The cold recovery score (CRS) of RILs was recorded after 4 days recovery period according to standard evaluation system (SES, IRRI). Total of eight QTLs were detected on chromosome 1, 7, 8, 10, 11 and 12 using cold tolerance traits, chlorophyll content, seedling discoloration and cold recovery score in 384 RILs. The qCRS12, which detected on chromosome 12 between two flanking markers id12002113, id12002563 (1.1 Mbp) showed 25 LOD score with 26% of phenotypic variation of cold recovery score in RILs population. The positive allele contributing to cold tolerance came from the cold tolerant parent Unkwang. The result may provide useful information for a marker-assisted breeding program to improve cold tolerant in rice.