Temperature rise during grain filling stage by global warming causes deterioration in rice yield and quality. This study was conducted to investigate proper panicle traits for improving grain filling under high temperature. A total of 40 Korean rice cultivars were grouped according to maturation period and exposed to high temperature during grain filling stage in greenhouse with ventilating fans. Average temperature in greenhouse was 1.1～1.5oC higher than ambient condition. Main panicle traits such as number of spikelets per panicle, number of primary rachis branches(PRBs) and secondary rachis branches(SRBs) per panicle, number of spikelets setting on PRBs and SRBs were counted after harvest and their relationship with grain ripened ratio was investigated. Grain ripened ratio under high temperature showed significant negative correlations with number of spikelets per panicle, number of total rachis branches, number of SRBs, number of total and average spikelets setting on SRBs, and ratio of number of SRBs to number of PRBs. Especially, number of total and average spikelets setting on SRBs showed highly negative correlations with ripened grain ratio, which implies grain filling under high temperature might have been more severely decreased in the cultivars with bigger sink size due to higher number of spikelets setting on SRBs.

Korean Japonica resistant rice cultivars mainly posses one of the genes, Xa1 or Xa3 for BB resistance. These resistance genes are becoming susceptible to K3a, resulting in the breakdown of resistance of Japonica cultivars. Especially, glutinous rice cultivars exhibit high susceptibility to bacterial blight(BB) in Korea. This study was carried out to develop glutinous Japonica near-isogenic lines(NILs) conferring useful single gene such as Xa2, Xa3, xa5, Xa21, etc. Six NILs conferring Xa2, Xa3, xa5, xa8, Xa14 and Xa21 genes were developed. Six NILs with Sangjuchalbyeo genetic background were selected by DNA markers and inoculation of K1, K2, K3 and K3a race. NILs having Xa14 was resistant to K1 and susceptible to K2, K3 and K3a. NILs with Xa2 and xa8 was resistant to K1, K2 and susceptible to K3 and K3a. NIL with Xa3 was resistant to K1, K2, K3, but susceptible to K3a. NIL with xa5 was resistant to K1, K2, K3, and K3a. NIL having Xa21 was susceptible to K1, while resistant to K2, K3 and K3a. Identification of xa5 and Xa21 genes were carried out by STS markers. Heading date of NILs ranged from Jul. 31 to Aug. 6. Culm length, No. of grains per panicle and ratio of ripened grain of NILs were a little different to those of Sangjuchalbyeo. Milled rice of NILs were ranged from 437kg/10a to 463. Agronomic traits of NILs containing Xa2, Xa3, xa5, xa8, Xa14 and Xa21 were similar or a little different to those of recurrent parent. These NILs would be useful to develop durable resistant glutinous varieties in Korea.

This study was carried out to confirm the effects of climate change to growth, yield and quality of rice by the global warming. By the study of Korea Meteorology Administration, the temperature of Korea increased 0.95℃ during last 34 years and the width of temperature increase be on an increasing trend gradually. As temperature increases, rice is faced with critical change such as growth duration shortening, heading acceleration, yield decrease and quality deterioration. So, we studied the rice growth and yield change by the temperature increase. To confirm the effects of temperature increase, rice cultivars such as early maturing Unkwangbyeo, medium maturing Hwayoungbyeo and late maturing Nampyeongbyeo were transplanted on 1, 15, 30 of June inner transparent vinyl house which was treated by different temperature. The increased mean temperature were 1.4℃～3.5℃, respectively, compared to outer field. The growth duration from transplanting to heading were shortened by the temperature increase. In June 1 transplanting, especially the growth duration of early maturing Unkwangbyeo was shortened greatly by temperature increase. As temperature increases, rice yield decreased in most cases. In 1.4℃ temperature increase, rice yield of June 15 transplanting were higher than those of other transplanting, but in 2.1℃ or more temperature increase, the rice yield of June 30 transplanting were similar or more than those of other transplanting.

To select rice cultivars adaptable to low fertilization in puddled soil drill seeding, 20 rice cultivars were tested in Iksan. The seedling stand ratio of Kwanganbyeo, Junganbyeo, Saegyehwabyeo, Pyeonganbyeo were higher than 80%, but those of Hwalangbyeo, Hoanbyeo were lower than 60%. The tiller number per m2 was 4% smaller in low fertilization compared to conventional fertilization level. In low fertilization, the decrease rate of tiller number per m2 were less than 1～2% in Ansanbyeo, Juan 1, Geumanbyeo and Hoanbyeo, but more than 6～9% in Junganbyeo, Hwaanbyeo, Daesanbyeo and Saegyehwabyeo. Harvest index was 2.8% higher in low fertilization compared to conventional fertilization level. Nonganbyeo, Hopumbyeo, Dongjin 2 and Saegyehwabyeo showed high harvest index, but Gwanganbyeo, Geumanbyeo and Hwalangbyeo showed low harvest index. In low fertilization, milled rice protein content were lower than 6.0% in 14 rice cultivars including Juanbyeo and Kwanganbyeo, but 6.1～6.4% in other rice cultivars. Rice yield decreased 6% in low fertilization compared to conventional fertilization. Rice yield decrease were smaller as 2～3% in Hoanbyeo, Juanbyeo, Kwanganbyeo, Chengdambyeo, Geumanbyeo and Donganbyeo, but bigger as 7～8% in Nonganbyeo, Nonghobyeo. Dongjin 2, Saegyehwabyeo and Ansanbyeo. Owing to 2.4% increase of head rice ratio in low fertilization compared to conventional fertilization, head rice yield decreased 4% in low fertilization. Cultivating rice in puddled soil drill seeding with low fertilization, the rice cultivars such as Kwanganbyeo, Hopumbyeo, Pyeonganbyeo and Dong 2 showed lower than 6.0% milled rice protein content and more than 470㎏/10a milled rice yield.

This study was conducted to select suitable rice cultivars for high-quality rice production in silage barley-rice double cropping in Honam plain area by National Institute of Crop Science from 2008 to 2009. Heading dates of all tested cultivars were before the safe heading limit(Aug. 31). Rice yield was superior in "Keunseom", "Hanareum", "Hanmaeum", "Onnuri", "Hopum", "Juan 1", "Dongjin 1", and was little in "Daepyeong", "Hwasin", "Malgeumi", "Chilbo", "Nampyeong", "Hopyeong". Protein content was high in "Hanareum", "Keunseom", "Chilbo", "Nampyeong", and was low in "Hanmaeum", "Dami", "Sindongjin", "Pyeongan", "Samgwang". And head rice ratio was high in "Malgeumi", "Hwanggeumnuri", "Samgwang", and was low in "Keunseom", "Hanareum", "Dami", "Hanmaeum", "Hwasin". In consideration of all the factors, in conclusion, proper cultivars for silage barley-rice double cropping are "Onnuri", "Hwanggeumnuri", "Hopum", "Dongjin 1", "Juan 1".

This study was conducted to investigate the variation of rice quality and the effect of labor-saving by using slow-releasing fertilizer when doing direct drill seeding on flooded paddy surface by large scale direct drill seeding machine in Honam plain area. The results obtained by changing the amount of slow-releasing fertilizer in 2008, 2009 are as follows. Considering rice growth, head rice yield and rice quality, the optimum amount of slow-releasing fertilizer was 7kg/10a, when doing direct drill seeding on flooded paddy surface in southern plain area of Korea. When using slow-releasing fertilizer 7kg/10a, the protein content became lower, and head rice ratio became higher than that of conventional nitrogen split application method as basal fertilization, top dressing at tillering stage, fertilization at panicle initiation stage.

“aegseolchal”is a new Japonica type waxi rice variety developed and registered by the rice breeding team of Department of Rice and Winter Cereal Crop, NICS, RDA in 2007. This variety was derived from a across between Iksan435 which is highly tolerant to lodging and high yield potential, and Iksan425 which is resistance to multiple diseases. This variety has about 120 days of growth duration from transplanting to harvesting in middle, Honam and Youngnam plain of Korea. It is about 80 cm in culm length and tolerant to lodging. It is moderately resistant to blast, and resistance to bacterial blight pathogen races from K1 to K3, but susceptible to other major diseases and insect pests. “aegseolchal”is midium-short grain and the milled rice exhibits high whiteness. The milled rice yield was about 5.37 MT/ha in local adaptability test for three years. “aegseolchal” would be adaptable to plain areas south of the Chungnam Province of Korea.

Starch RVA profile parameters serve as important indices in the estimation of rice cooking and eating quality. Four cold- tolerant and five cold-sensitive japonica rice varieties grown at 3 different altitudes in Yunnan plateau were used in this experiments. RVA parameters including peak viscosity(PKV), hot viscosity(HTV), final viscosity(FLV), breakdown viscosity(BDV), setback viscosity(SBV) and pasting temperature(PaT) were investigated. SBV and PaT of cold tolerant varieties and PKV, BDV and SBV of cold-sensitive varieties were significantly influenced by environments. The variances of RVA parameters were affected by genotype×environment interactions in cold tolerant and sensitive varieties. The coefficients of variation of RVA parameters except for SBV in cold tolerant varieties were lower than those in cold sensitive varieties. HTV, FLV and SBV of cold tolerant varieties were significantly lower, while PKV, BDV and PaT were significantly higher than those of cold sensitive varieties. With altitude increasing, SBV and PaT of cold sensitive varieties increased significantly, whereas PKV, HTV, FLV and BDV decreased significantly. However, PKV, BDV and PaT of cold tolerant varieties gradually increased while HTV, FLV and SBV increased and then gradually decreased with altitude rising. These results suggested that cooking and eating quality would be improved by improving cold tolerance of rice varieties in breeding program.

This study was conducted to examine the appropriate transplanting date of the top-quality rice variety, Unkwangbyeo, in Honam plain area. The results obtained from 2006 to 2007 in Iksan are as follows. The number of panicle per m2 increased as the transplanting date became late and the number of grain per m2 was the highest in the plot of which the transplanting date was June 15. Percent ripened grain increased as the transplanting date became late until June 15, however, it decreased in the plot of which the transplanting date was June 30. Imperfect grain increased as the transplanting date became early due to the occurrence of immature rice and cracked rice. Protein content increased as the transplanting date became late, but didn't show statistical significance. Toyo texture increased as the transplanting date became late. Rice yield and the head rice yield increased as the transplanting date became late until June 15, however, they decreased in the plot of which the transplanting date was June 30. Even though the rice price was high in early transplanting cultivation, gross profit was the highest in June 15 transplanting since the rice yield increased as the transplanting date became late until June 15. Considering the yield, rice quality and profit, the most appropriate transplanting date of Unkwangbyeo in Honam plain area is the middle of June.

This study was conducted to make breeding program for improving milling traits, which has difference among the rice varieties. Milling traits such as residual embryo ratio, broken kernel ratio and whiteness were investigated at the different milling level and with several varieties. Residual embryo ratio and broken kernel ratio were high at the varieties group having more 1000-grain weight. In the whiteness of milled rice, there was also variance among the varieties at the same degree of milling. Correlation analysis among milling traits showed that there is positive correlation between 1000-grain weight and recovery of brown rice, but negative correlation between protein content of brown rice and hardness of kernel. Therefore, these different milling traits of each varieties could be considered in the rice breeding program for the good quality.

Japonica rice cultivars exhibit high susceptibility to BB disease due to genetic vulnerability in Korea. Korean Japonica rice cultivars mainly posses the genes, Xa1 and Xa3 for BB resistance. These resistance genes are becoming susceptible to K3a, new races of BB, resulting in the breakdown of resistance in high yielding Japonica cultivars. It is imperative to look for novel R-genes for improvement of japonica rice resistant to BB races. This study was carried out to conform useful single gene resistant to 24 BB isolates (including K3a, HB01009) breaking down Xa3 gene. Cultivars and near-isogenic lines (NILs) carrying Xa1, Xa2, xa8, Xa10, Xa11, xa13 genes were susceptible to 24 isolates, whereas IRBB4 carrying Xa4 gene was moderate resistance. IRBB5 and IRBB21 having xa5 and Xa21 genes, respectively, expressed resistance to these isolates. IRBB7 having Xa7 gene showed resistance response to 24 BB isolates, whereas JBB-107 carrying Xa7 gene was susceptible to 10 BB isolates and moderate resistant to 14 BB isolates. Xa7 gene showed different resistance response according to genetic background of used recurrent parent. With these findings, Xa4, xa5, and Xa21 would be the most prospective genes to 24 isolates used in screening.

This study was carried out to develop rice growth model when cultivate early maturing rice cultivar, Unkwangbyeo, in Honam plain area. To confirm leaf emergence rate and variation of heading date, we transplanted 15 day and 30 day old seedling on May 1, May 15, May 31, June 15, June 30, respectively. The growth duration between transplanting and completion of leaf emergence on main culm were 50.1~78.3 days in 2007 and 47.5~74.7 days in 2008. Growth duration diminished gradually as transplanting time delayed, but the difference of growth duration by transplanting time were more bigger than that of seedling day. The emerged leaf number after transplanting on main culm were 8.9~10.9 in 2007 and 8.4~10.9, respectively. The emerged leaf number diminished as transplanting time delayed, but the difference of emerged leaf number by transplanting time were more bigger than that of seedling day. The cumulative temperature between transplanting and completion of leaf emergence on main culm were 1,281~1,650℃ in 2007 and 1216~1560℃ in 2008. The solar radiation between transplanting time and completion of leaf emergence on main culm were 709~1,245MJ/㎡ in 2007 and 722~1,220 MJ/㎡ in 2008. The sunshine hours between transplanting time and completion of leaf emergence on main culm 234~433 hours and 238~431 hours, respectively.

This study was carried out to attain the basic data which will be used in the selection of adaptable varieties in honam plain area for the production of high quality rice. 12 varieties including Unkwang, Hwayeoung and Nampyeong were tested in southern plain area, Iksan. The number of panicles per ㎡ was the highest in Hopyeong, the lowest in Sindongjin, and that of other varieties was around 350. The mean percentage of effective tillers was the highest in early maturing varieties, the lowest in Ilpum, Nampyeong and Junam, and that of other varieties was around 75%. The number of total seeds was the highest in Hopyeong which had the high number of panicle per ㎡ and in Dongjin 1 which had the high number of seeds per panicle. That of Hwayeong, Sindongjin and Odae was the lowest, respectively. Percent ripened grain of the early maturing varieties was lower than the medium maturing and medium-late maturing varieties showing 93% in Hwayeong, Ilmi and Samkwang which is the highest, and 83% in Unkwang which is the lowest. Head rice ratio was high in Nampyeong, Hwayeong and Ilmi, and low in early maturing varieties, Unkwang and Odae. Protein content was high in Odae, Hwayeong and Nampyeong, and low in Sindongjin, Samkwang and Pyeongan. The rice yield was high in Sindongjin, Unkwang, Ilmi and Dongjin 1 showing more than 500kg/10a, while the head rice yield was high in Nampyeong, Dongjin1 and Sindongjin, and low in Ilpum and Odae.

“unbora”is a new japonica rice cultivar developed from a cross between Iksan433 resistant to bacterial blight and Miyadamamochi, a waxy line. at Honam Agricultural Research Institute, NICS, RDA, in 2006. This cultivar is a short grain shape and about 118 days of growth duration from transplanting “unbora”to harvesting under Korean climatic conditions. The milled rice are snow white and glutinuous. This cultivar shows high resistant reactions to the bacterial blight pathogen race K1～K3 and blast respectively. The milled rice yield of “unbora”is about 5.34 MT/ha under the standard fertilizer level of the ordinary transplanting cultivation. “unbora”would be adaptable for in the middle plain, north middle-mountin plain and Honam plain, and Youngnam plain areas of Korea.

Hwangeumnodeul is a new japonica rice cultivar developed from a cross between Milyang165 and HR15151-B-21-3 at Honam Agricultural Research Institute (HARI), NICS, RDA, in 2007. This cultivar has short grains and about 139 days of growth duration from direct seeding to harvesting in the southern plain areas. Culm length of this cultivar is 78 cm and the number of spikelet per panicle is similar to that of the check cultivar, Nampyeongbyeo, while filled grain rate is lower than the check variety. This cultivar is moderately resistant to leaf blast, bacterial blight pathogens of K1, K2 and K3 and stripe virus but susceptible to major virus diseases and insect pests. Milled kernel of Hwanggeumnodeul is translucent with non-glutinous endosperm. This cultivar has about 5.7% and 18.6% of protein and amylose contents, respectively. Palatability of cooked rice of Hwanggeumnodeul is similar to Nampyeongbyeo. Its milling recovery and head rice were 75.6% and 90.0%, respectively. Hwanggeumnodeul yielded 5.69 and 5.61 MT/ha in milled rice at the under wet-direct and dry-direct seeding conditions, respectively which are 17% and 12% higher than the check variety, Juanbyeo. It yielded 5.86 MT/ha, 8% higher than Nampyeongbyeo at the standard fertilizer level of the ordinary transplanting cultivation. “wanggeumnodeul”would be adaptable for ordinary transplanting as well as direct seeding in the southern plain including Chungcheong province.

“Dami”is a new japonica rice variety developed and registered by the rice breeding team of Honam Agricultural Research Institute, NICS, RDA in 2006. This variety was derived from a cross between Iksan438 with lodging tolerance and high yield potential, and Iksan426 This variety has about 122 days of growth duration from transplanting to harvesting in Honam and Youngnam plain of Korea. It is about 83 cm in culm length and tolerance to lodging. In reaction to biotic stresses, it shows moderately resistance to blast, and resistance to bacterial blight pathogen races from K1 to K3, but susceptible to other major diseases and insect pests. The milled rice of “ami”has high Quality, midium short grain. The milled rice yield of this variety is about 5.92 MT/ha in local adaptability test for three years. “ami”would be adaptable to Middle plain, Honam plain and Youngnam plain area of Korea.

This study was carried out to get the genetic information on the germination rate and fat acidity after 12 weeks’storage at 35 . Germination rate decreased with longer storage period, ℃ while fat acidity increased. Germination rate was higher in the order of Koshihikari, Hanmaeum and Unkwangbyeo after 12 weeks’storage at 35℃. Fat acidity of Koshihikari and Hanmaeum was gradually increased, but that of Unkwangbyeo was dramatically increased after 4 weeks’storage at 35℃. The genetic mode on germination rate and fat acidity using the joint scaling test was shown to be additive-dominance gene effects. Additive([d]) effect was higher than dominance effect([h]) in all crosses. The average degree of dominance, [h]/[d], was less than 1, indicating that germination rate and fat acidity was partially dominant. Germination rate and fat acidity based on frequency distribution of 2 crosses were quantitative characters expressed by polygenes.

This study was conducted to investigate the relations between brown planthopper (BPH, Nilapavata lugens) resistance and specific organic acids (oxalic acid, silicic acid, and trans-aconitic acid) known as BPH sucking inhibitors on different rice varieties and/or lines. There were no specific relations between BPH resistance and the contents of oxalic and silicic acids in the rice plant tissues. However, the stronger the BPH resistance was occurred, the higher the content of trans-aconitic acid was contained in the rice plants. The relations between the injury rate of rice plant by BPH and the content of trans-aconitic acid in the rice plants were negatively correlated, which were -0.84 and -0.82 at 30 and 60 days after seeding, respectively. Therefore, the content of trans-aconitic acid in rice plant tissues might be utilized as an index for improving BPH resistance of rice varieties.

This study was conducted in 2002 and 2003 to investigate variation on rice quality associated with cooking, and eating qualities under the three different fertilizer levels, none fertilizer level(N-P2O5-K2O=0-0-0kg/ha ), ordinary fertilizer level(N-P2O5-K2O=1l0-45-57kg/ha ), and heavy fertilizer level(N-P2O5-K2O=180-90-110kg/ha ). The eight resistant near-isogenic lines(NILs) for bacterial blight in rice were examined for grain appearances, several physicochemical properties, and palatability value measured by Toyo taste meter. Significant variations in NILs(V), Years(Y), and VxY interaction were recognized in grain length and palatability value under the none fertilizer cultivation, in grain width under the heavy fertilizer cultivation, and in white belly ratio under the three different fertilizer cultivations, respectively. According to increase the fertilizer application rate, variation in grain length and grain width were not significant, but grain thickness was thinner under the ordinary and heavy fertilizer cultivations than under the none fertilizer cultivation. On the other hand, white belly ratio, protein content and Mg/K ratio increased, while amylose content and palatability value lowered. Alkali spreading value lowed under the heavy fertilizer cultivation than under the none and ordinary fertilizer cultivations. Palatability value was significantly low in the line carrying XalJ than in the other lines under the ordinary fertilizer cultivations.

Rice production in Korea has markedly increased during the last two decades due to newly developed high yielding varieties and improved production technology. This experiment was conducted to determine the potential of tropical japonica germplasm in enhancing the yield of temperate japonica. The yield performance of two tropical japonicas (IR 65597-29-3-2 and IR66154-52-1-2) and one temperate japonica (Dongjinbyeo) was compared at different plant densities and nitrogen levels under Korean environmental conditions. Although tropical japonicas showed low tillering habit and large panicles, they had similar leaf area index and dry weight at heading stage to Dongjinbyeo of the high tillering type indicating that there was not much difference between tropical and temperate japonica in terms of biomass production. The highest milled rice yield of 6.15 t/ha was obtained from Dongjinbyeo at a high nitrogen level with less planting density (220 kg N/ha and 30 ~times 15 cm). However, those of the two tropical japonicas were 5.36 t/ha at the condition of 165 kg N/ha and 30 x 10 cm planting density and 5.06 t/ha at the condition of 165kgN/ha and 15 x 15 cm planting density, respectively. Ripened grain of tropical japonicas ranged from 65 to 87%, while that Dongjinbyeo ranged from 82 to 97% under Korean conditions.