• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.460-463
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• 2008

The change of glutelin contents in rice grain during the maturity period was investigated to determine optimum rice harvesting time. The glutelin content was increased with increasing time after heading. In this study, eight of glutelin subunits were found. Among the glutelin subunits, 7208-subunit (MW, 35 kD) contents was significantly increased at 65 days after heading compared with 55 and 60 days after heading. 7405-subunit (MW, 50 kD) contents was steadily increased with time after heading. The results showed that at 55th day after heading would be optimum time for harvest to get the low glutelin content of rice grain.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.3
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• pp.191-199
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• 2003

Optimum transplanting time for extremely early rice cultivation as an after-crop of fruit and vegetables under greenhouse conditions in the southern area was determined. Rice was transplanted on March 10, March 20, March 30, April 10 and April 20 far three years from 1998 to 2000. Meteorological computations for rice production were high for heading between early May and early July, but they were too low for heading between late July and early August. Especially the expected yield predicted with 35,000 spikelets, the average spikelets per $m^2$ for extremely early transplanting. Computation for heading between late July and early August was low by 106 kg/10a compared with that yield at heading during the same period in the field. As the transplanting date in extremely early rice cultivation was earlier) rice growth at early stages was more retarded by low temperature. Rice growth at heading stage recovered with high temperature, showing less difference for the transplanting date. Abnormal tillers occurred by 15.5∼22.2%. The contribution of 1,000 grain weight${\times}$ripened grain ratio to yield of the extremely early rice cultivation in the greenhouse was 50.6%, indicating 16% hi일or than the degree of panicle per $m^2$ on yield. The estimated optimum transplanting time on the basis of yield for the extremely early greenhouse rice cultivation ranged from March 19 to April 28, and the estimated critical transplanting date on the basis of accumulated effective temperature was March 12. Rice reduced the amount of NO$_3$-N by 97.1% and EC by 90.5% in greenhouse soil with continuous fruit/vegetables fer more than a 10-year period, and completely removed the root-knot nematodes.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.10-12
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• 2003

This study was to monitor changes of leaf area index (LAI) and normalized difference vegetation index (NDVI), calculated from ground-based remotely sensed high resolution reflectance spectra, during rice (Oryza sativa L. cv. TNG 67) growth so as to determine their relationships and the optimum time period to use these parameters for yield prediction. Field experiments were conducted at the experimental farm of TARI to obtain various scales of grain yield and values of LAI and NDVI in the first and the second cropping seasons of 2001-2002. It was found that LAI and NDVI can be mutually estimated through an exponential relationship, and hence plant growth information and spectral remote sensing data become complementary counterparts through this linkage. Correlation between yield and LAI was best fitted to a nonlinear function since about 7 weeks after transplanting (WAT). The accumulated and the mean values of LAI from 15 days before heading (DBH) to 15 days after heading (DAH) were the optimum time period to predict rice yield for First Crops, while values calculated from 15 DBH to 10 DAH were the optimal timing for Second Crops.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.2
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• pp.124-131
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• 1995

In order to find out optimum seed production date according to different defoliation and flooding period of Italian ryegrass, this studies with Tetrone were canied out on the experimental field of Honam Crop Experiment Station from 1986 to 1988. Treatments included cutting date of Nov. 20 and Apr. 10 and flooding period of 5-25 days. In soil after experiment, organic matter, phosphate and silicate content increased, but potassium content decreased 0.16% than that before experiment. Heading and maturing date of Nov. 20 cutting were same with those of non cutting, those of Apr. 10 cutting lates 6 days to heading date and 2 days to maturing date. Plant height and culm length of Nov. 20 cutting were sirniller to those of non cutting, those of Apr. 10 cutting were shorter and panicle length have no difference between non cutting and cutting. Lodging of cutting treatment was reduced than that of non cutting. Lodgin was increased as flooding period was long, also loding of all treatment occured at 30 days after heading. Two cutting times of Nov. 20 and Apr. 10 have the most fresh yield, while non cutting have the most dry matter yield. Optimun seed productin date was considered to suitable when 35 days after heading (Jun. 14), at this time, seed production was 1,640 to 2,640 kg/ha. Also if flooding j u r y have, seed production was good between 10 days and 15 days after flooding.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.1
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• pp.17-28
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• 2007

This study was conducted to analyze the optimum heading period according to the recent climatic change for improvement of rice yield and grain quality in the Yeongnam area. We analyzed climatic elements including daily mean air temperature, daily range of air temperature, sunshine hours, and amount of precipitation from 1996 to 2005 in comparison with those of the 1971 to 2000 normal. Daily mean air temperature and amount of precipitation in the recent 10 years increased, but daily range of air temperature and sunshine hours decreased in comparison with the norm. Also, monthly mean air temperature was lowered remarkably in July and August. The monthly amount of precipitation largely increased in August and September. The daily range of air temperature and sunshine hours were greatly decreased from August to October, Possible cultivation periods for rice in the recent 10 years ranged from 171 days in Boughwa to 228 days in Busan and was expanded about $1{\sim}13$ days in comparison with the normal. Optimum heading date by local regions for the maximum climatic yield potential was estimated as July 31 at Bonghwa to September 7 at Busan, Masan, and Tongyeong in the recent 10 years. There was a wide difference in optimum heading date according to local legions of the Yeongnam area. Compared to the normal, optimum heading date in the recent 10 years was delayed about I~8 days in most local regions except Bonghwa, Mungyeong, and Yeongdeok. These results suggested that it is necessary to develop late maturity rice cultivars for producing high yield and quality rice grain due to the recent climatic change. Moreover, it is still more important to select the most suitable cultivation period appropriate to the changed climate of each local region in Yeongnam area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.289-296
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• 2021

This study aimed to analyze the optimal transplanting date of the floury endosperm rice varieties Hangaru, Seolgeang, Singil, and Baromi2 allowing to reduce the viviparity rate. The viviparity rate rapidly increased with the mean temperature during the ripening stage. Therefore, to reduce the viviparity rate, we calculated the optimum heading date based on the safe heading date limit in each area so that the ripening stage occurred at lower temperatures. hen, the effects of changes in heading date were monitored by recording the transplanting date and the temperature during the growth period. The transplanting date was highly correlated with the number of heading days in the field. Therefore, the optimum transplanting date was calculated according to the transplanting date in each area. When the accumulated temperature was 700℃, if floury rice was transplanted at the optimum transplanting date, the mean temperature was approximately 20℃. When the accumulated temperature was 900℃, the mean temperature was approximately 18℃. Under these conditions, the viviparity rates of Hangaru, Seolgeang, and Singil rice were lower than 10%. However, Baromi2 showed a high viviparity rate. These results suggest that the viviparity rate of Hangaru, Seolgeang, and Singil rice can be reduced by transplanting at the optimum transplanting date. However, further research is required for pinpointing the optimum transplanting date of Baromi2 rice.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.3
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• pp.203-212
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• 1993

This experiments were carried out to estimate the optimum final cutting date in autumn and the selection of highly adaptable varieties in mountainous pastures of Taekwalyong area. The evaluations were based on the data of varietal differences of dry weight of plant(DW) and yield components of the 1st cutting as affected by various final cutting dates of last autumn. Nine varieties of tall fescue Barvetia, Fuego. Demeter, Safe. Barcel, Forager, Johnstone, Enforcer and Stef. were used and 4 final cutting date of autumn were $C_1$, cut on 30 Sept. $C_2$, on 14 Oct. $C_3$, on 28 Oct. and $C_4$. on 11 Nov.. respectively. The results obtained were as follows: I . Between the dry weight of plant(DM) and yield components of 1st cutting were different by various final cutting dates of autumn. The dry weight of plant(DW) was significantly positive correlated with heading characteristics of the 1st cutting in earlier cuttings($C_1- C_3$) of autumn, but there was not significant correlated with heading characteristics of the 1st cutting in the latest cutting($C_4$) of autumn. 2. The variety of Forager with heavier weight of heading tiller(HTW) and dry weight of tiller(WT) showed the highest dry weight of plant(DW) of the 1st cutting in earlier cuttings($C_1-C_3$) of autumn, whereas the variety of Barcel with high number of tillers per plant(NT) showed a high dry weight of plant(DW) of the 1st cutting in the latest cutting($C_4$) of autumn. 3. Optimum final cutting date and critical period of mountainous pastures in Taekwalyong area were estimated in late September($C_1$) and middle October($C_2$), sespectirety. 4. The dry weight of plant(DW) of the 1st cutting was significantly negative correlated with final cutting dates in growth period of autumn.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.2
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• pp.65-73
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• 1979

Experiment was conducted to study the optimum sowing date and nursery duration at Jean An from 1976 to 1978 and their influence on the growth, dry matter production during growth period of the rice plant. In case of Tongil lines, the lengthening of nursery duration and late sowing increased unexpected heading and prolonged heading and maturing period. High yield were obtained by increasing dry matter accumulation during growth period of rice plant. To obtain safe yield in Tongil lines transplanting must be done before May 30th.

• Korean Journal of Soil Science and Fertilizer
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• v.5 no.2
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• pp.75-82
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• 1972

The proposed hypothesis that the effects of climatic factors during ripening period (from 10 days before heading to 30 days after heading) on ripened grain ratio are equal on the level of canopy and on the level of tiller in that canopy of rice plant appeared to be agreeable. The followings were found according to the analysis of ripening structure at tiller level. 1. The optimum ripening temperature (mean air temperature during ripening period) was $21^{\circ}C$ for Jinheung and $22^{\circ}C$ for IR667-Suwon 214. 2. The minimum mean solar radiation ($cal\;cm^{-2}\;day^{-1}$) of ripening period was not greater than 240 for Jinheung and greater than 270 for IR 667-Suwon 214. 3. The ripened grain ratio was not different from main culm to first tillers of second order of main culm in Jinheung but greatly decreased from 4th tiller of first order of main culm in IR667 and the number of grain per main culm was greater in IR667 than in Jinheung indicating that yield of IR667 could be increased by increasing the number of main culm. 4. The last heading date insuring optimum ripening period appeared to be 25th in August for Jinheung and 30th in August for IR667 in Suweon.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.3
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• pp.213-220
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• 1993

This experiments were carries out to estimate the optimum final cutting date in autumn and the selection of highly adaptable varieties in mountainous pastures of Taekwalyong area. The evaluations were based on the data of varietal differences of dry weight of lant(DW) and yield components of the 1st cutting as affected by various final cutting dates of last autumn. Nine varieties of fall fescue Barvetia, Fuego, Demeter, Safe Barcel Forager, Johnstone, Enforcer and Stef, were used and 4 final cutting date of autumn were $C_1$, cut on 30 Sept. $C_2$, on 14 Oct. $C_3$, on 28 Oct. and $C_4$ on 11 Nov.. respectively. The results obtained were as follows; 1. Between the dry weight of plant(DM) and yield components of 1st cutting were different by various final cutting dates of autumn. The dry weight of plant(DW) was significantly positive correlated with heading characteristics of the 1st cutting in earlier cuttings$(C_1-C_3)$ of autumn, but there was not significant correlated with heading characteristics of the 1st cutting in the latest cutting$(C_4)$ of autumn. 2. The variety of Forager with heavier weight of heading tiller(HTW) and dry weight of tiller(WT) showed the highest dry weight plant(DW) of the 1st cutting in earlier cuttings$(C_1-C_3)$ of autumn, whereas the variety of Barcel with high number of tillers per plant(NT) showed a high dry weight of plant(DW) of the 1st cutting in the latest cutting$(C_4)$ of autumn. 3. Optimum final cutting date and critical period of mountainous pastures in Taekwalyong area were estimated in late September$(C_1)$ and middle October$(C_2)$, sespectirety. 4. The dry weight of plant(DW) of the 1st cutting was significantly negative correlated with final cutting dates in growth period of autumn.