• Korean Journal of Soil Science and Fertilizer
• /
• v.8 no.2
• /
• pp.105-111
• /
• 1975

Nitrogen efficiency for grain yield(E) and its relation to grain yield(Y), harvesting index(HI), percent translocation of nitrogen from straw to grain(T), nitrogen uptake amount(N), concentration in grain (GN%) or straw (SN%) and total dry matter yield (TY) among rice varieties (Oryza sativa, old and new varieties) were investigated at four nitrogen nutritional status (high and low fertilizer levels in high and low fertility fields) by simple correlation analysis. Relation between any two of above parameters or total dry matter yield (TY) and nitrogen efficiency for total dry matter yield (TE) was also investigated. 1. E is significantly and positively correlated with T, Y, HI but negatively with SN%, N, GN% and in negative trend with TY. 2. T is significantly and positively with GN% or Y, but negatively with SN%. 3. TE is significantly and positively correlated with TY but negatively with N. 4. The order of E among varieties showed consistency among different nitrogen nutritional environments. 5. From the above facts it was concluded that high yielding varieties have high nitrogen efficiency due to high percent translocation of nitrogen from straw to grain, subsequent low nitrogen concentration in straw and that translocated nitrogen in grain is greatly diluted with photosynthates. 6. Reported physiological characteristics of newly bred high yielding IR lines are well accordance with their high nitrogen efficiency and rice breeding was a selection on the basis of nitrogen efficiency. 7. It is postulated that high nitrogen efficiency varieties for yields have high nitrogen efficiency for root growth in early stage so that uptake more efficient soil nitrogen in later growth stage.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.19
• /
• pp.1-6
• /
• 1975

From the cross Tongil$^2//IR833/IR1317$ glutinouse rice lines wx 126 were bred. Some of these lines were earlier than standard variety and later than glutinous check variety. Some of them yielded as much as standard variety and showed better resostances to blast, stripe deseases and smaller brown plant hopper than standard variety. It was sosscussed that, theough the vreedong procedure, following points were proved, 1)back-cross program in roce breeding was effocoent, 2)semi-dwarf plant type of "Tongil" has high yielding poteneoality and 3) the variety "Tongil" was a good for recurrent parent for back-cross program. back-cross program.

• Korean Journal of Agricultural Science
• /
• v.41 no.4
• /
• pp.327-334
• /
• 2014

Light intensity is one of the most important requirements for plant growth, affecting growth, development, survival, and crop productivity. Sunlight is the main energy source on Earth which is energy used by photosynthesis to convert light energy to chemical energy. In this study, the light use efficiency and photosynthetic characteristics of high-quality rice cultivars were evaluated after shading on ripening stage. For the study, we treated of three levels of shade (0, 50 and 70%) on rice at ripening stage and two levels of nitrogen (9 and 18 kg/10a) used three high yielding rice cultivars, such as Boramchan, Hopum, and Honong. The shade was given for the respective plots from heading up to harvesting. We were performed to determine growth survey, SPAD and chlorophyll fluorescence every 10 days interval after shading on ripening stage. At harvest stage, grain yield and yield components were determined. Results of analysis of the results representing the maximum photosynthetic efficiency of PSII, Fv/Fm, and SPAD were decreased by depending on the time at full sunlight. But shade treatments were not changed and a significant difference among cultivars did not appear. Compared with the full sunlight, shade treatments significantly delayed ripening rate and decreased rice quality of cultivated rice. Therefore, rice yield, can be reduced in proportion to the shading density is apparent, the rate of decrease was not observed difference between varieties, when protected from light 70%, and decreased to less than 50%. The adverse effects of low light intensity on the yield and yield components were not able to significantly minimize by the nitrogen level.

• Korean Journal of Breeding Science
• /
• v.50 no.4
• /
• pp.415-423
• /
• 2018

Rice panicle architecture is an important factor affecting yield potential. Korean rice cultivars have a narrow genetic background for panicle architecture. To enhance the yield potential of Korean rice cultivars, we developed and characterized rice lines with new panicle architecture. Rice with improved panicle architecture has clustered spikelets and dense panicles (CD type). CD rice was derived from a cross between "Binhae Col.#1" carrying dense panicles, and "ARC10319" that has the clustered spikelets gene (Cl). CD rice lines had short and semi-erect panicles with two to five high density spikelets clustered at the tips of primary and secondary rachis branches. CD rice lines had dramatically increased numbers of spikelets; almost twice as many as those of Korean rice cultivars. The increase in spikelet number was mainly caused by the increased spikelets and branches on secondary rachises compared to those on primary rachises. The increase in spikelet number was expected to enhance the yield of CD rice by expanding sink capacity. However, the yield of selected lines; CD9, CD27, CD34, and CD39, did not reach the level of the Korean high-yielding cultivars "Boramchan" and "Hanareum2," due to the reduction in panicle number and grain weight, and poor ripening. Although no substantial yield increase was observed in CD rice, the panicle architecture of CD rice, clustered spikelets, and dense panicles could be new genetic resources as breeding material for diversifying panicle architecture and enhancing yield potential.

• Korean Journal of Breeding Science
• /
• v.43 no.6
• /
• pp.538-542
• /
• 2011

A new malting barley variety, 'Baegho', was developed from a cross between Azuma Golden and Nishinochikara in 1998. An elite line, YMB2139-2B-1-10-2, was selected in 2005 and designated as Milyang137. It showed good agronomic performance in the regional adaptation yield trials (RYT) from 2006 to 2008 and was released with the name of 'Baegho' having high yielding and BaYMV and powdery mildew resistance. The average heading and maturing dates of 'Baegho' were April 21 and May 28, which were 3 and 2 day later than those of Hopum, check variety, at the RYT, respectively. 'Baegho' has shoter culm length (78 cm), more spikes ($1,062per\;m^2$) and heavier 1,000 grain weight (40.7 g) than those of Hopum, respectively. 'Baegho' is resistant to domestic BaYMV strains I, III and IV and powdery mildew at Iksan. In growth habit, 'Baegho' is close to type (IV) that is distinguished from other Korean malting barley cultivars, which could tolerant to premature heading damage that is major concern for the practice of the malting barley cropping. The yield potential of 'Baegho' in the RYT was about 5.57 MT/ha, which is about 13% higher than those of Hopum. This variety has good malting quality in grain and malting analysis showed better 1,000 grain weight, husk rate, diastatic power than those of Hopum. 'Baegho' applied for protection of new varieties of plant in 2009.

• Korean Journal of Breeding Science
• /
• v.49 no.3
• /
• pp.250-255
• /
• 2017

'Hwaweon 7' was developed from a cross between the African upland cultivar, 'Moroberekan' and 'Ilpumbyeo' based on marker-aided backcross selection. The recurrent parent, Ilpumbyeo is a high grain quality cultivar with medium to late maturity. Hwaweon 7 is nearly isogenic to Ilpumbyeo except a small Moroberekan introgressed segment on chromosome 6 harboring genes related with spikelets per panicle and internode diameter. The preliminary and replicated yield trial was conducted at Chungnam National University and Chungcheongnamdo Agricultural Research & Extension (CARES), Yesan in 2010 and 2011. The local adaptability test was carried out by the National Seed Management Office (NSMO) in 2012 and 2013. This cultivar was registered to NSMO with a cultivar designated as "Hwaweon7". This cultivar averaged 80cm in culm length and has a medium growth duration. Milled rice of "Hwaweon7" is translucent and the grain quality traits are comparable to those of the recurrent parent. The average yield potential of Hwaweon 7 in grain was about 6.48 MT/ha at the ordinary fertilizer level for two years about 5.1% higher than that of Ilpumbyeo due to increase in spikelets per panicle. This variety is tolerant to lodging and the tolerance is due to the APO1 gene controlling the base internode diameter on chromosome 6 introgressed from the donor parent, Moroberekan. The Apo1 gene would be useful in enhancing resistance to lodging in rice breeding program.

• Korean Journal of Breeding Science
• /
• v.49 no.3
• /
• pp.280-284
• /
• 2017

'Hwaweon 6' was developed from a cross between 'Hwaseongbyeo' and a wild species, Oryza minuta L. (Acc. No. 101154) based on marker-assisted selection and backcrossing. The recurrent parent 'Hwaseongbyeo' is a high grain quality cultivar with medium maturity. Hwaweon 6 is nearly isogenic to Hwaseongbyeo except a small O. minuta introgressed segment on chromosome 7 harboring genes related with spikelets per panicle. The preliminary and replicated yield trial was conducted at Chungnam National University and Chungcheongnamdo Agricultural Research & Extension (CARES), Yesan in 2009 and 2010. The local adaptability test was carried out by the National Seed Management Office (NSMO) in 2011 and 2012. This cultivar was registered to NSMO with a cultivar designated as Hwaweon 6. This cultivar averaged 80cm in culm length and has a medium growth duration. Milled rice of Hwaweon 6 is translucent and the grain quality traits are comparable to those of the recurrent parent. The average yield potential of Hwaweon 6 in grain was about 6.57 MT/ha at the ordinary fertilizer level for two years about 3.0% higher than that of Hwaseongbyeo due to an introgression of the quantitative trait locus (QTL) for spikelets per panicle (qSPP7) from O. minuta. This variety is comparable to Hwaseongbyeo in low temperature germinability and cold tolerance. The qSPP7 QTL would be useful in enhancing yield potential in rice breeding program.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.62 no.3
• /
• pp.193-202
• /
• 2017

This study was carried out in 2014 and 2015 to investigate the effect of transplanting density on panicle production and to analyze the relationship of panicle production with yield traits in the mid-maturing quality rice cultivar 'Haiami' in the mid-plain area of Korea. Number of tillers per square meter increased by reducing planting distance and increasing seedling number per hill. These effects were maintained until maturity and were reflected in the final number of panicles per square meter, although the effect of planting density decreased as rice growth progressed. However, increased panicle number per square meter following dense planting did not improve head rice yield. Panicle number per square meter was negatively associated with spikelet number per panicle and was not correlated with other yield components or head rice yield. Head rice yield was not correlated with head rice percentage but was closely and positively correlated with milled rice yield. Milled rice yield did not increase with grain filling percentage but increased with spikelet number per square meter. Spikelet number per square meter increased with both spikelet number per panicle and panicle number per square meter, although the former had a greater influence. Therefore, we conclude that head rice yield of the 'Haiami' cultivar grown in the mid-plain area of Korea is not improved with an increased panicle number following high planting density but it could be improved with high milled rice yield by increasing spikelet number per unit area.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.32 no.1
• /
• pp.24-33
• /
• 1987

Competitive ability and response of grain yield in a mixed cropping of two cultivars having different agronomic traits were evaluated at the Yeongnam Crop Experiment Station in 1984 and 1985. Competitive ability was higher in Indica x Japonica cultivar, Milyang 23, and tall statured cultivar, Samgang-byeo, than in Japonica type cultivar, Nacdongbyeo, short statured type cultivar, Taebaegbyeo, respectively. Compared to pure stand, more grain yield was recorded when mixture rates were over 50% in a seed volume for the mixing rate of high yielding cultivar in two cultivars, but low compared to pure cultivation of the cul-tivar having the higher yielding ability in two cultivars.

• Korean Journal of Agricultural Science
• /
• v.6 no.1
• /
• pp.1-14
• /
• 1979

Selection index methods were applied to selecting better performing rice varieties with better plant characters from rice yielding trials tested under six different cultural methods. The results obtained were summarized as follows: 1. Varieties such as NO. 3, 4, 5 and 6 were selected as best performing varieties with good plant and grain characters. 2. Selection index I computed from Hazel's method was appeared effective for selecting rice varieties grown under general optimum environmental conditions, while selection index II computed from Pesek and Baker's desired genetic gain were effective for selecting rice varieties grown under rather stressed conditions. 3. The rank of mean yield of each variety was not completely in agreement with that of index values, which indicates the importance of other characters besides yield in selecting varieties. 4. Most characters studied were high in broad sense of heritabilities. 5. No significant interaction was found between varieties and cultural methods.