• Plant Resources
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• v.5 no.2
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• pp.155-160
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• 2002

The heading date is known to be controlled by two kinds of genetic constituent, photosensitivity and basic vegetable phase. For the latter, the effect of temperature in early growth period is critical to determine the shortness of vegetative growth periods in plant's life. A phytotron experiment on 55 rice cultivars, consisting of two ecotypes of rices, indica and japonica, was conducted at high and low temperature treatments at early growth stage to investigate the possible role of plant growth stimulus by high temperature to associate with shortening of heading date. The high temperature during the early growth stage stimulated the rice growth as measured by plant height with much difference of the growth response between indica and japonica. The conclusive finding that these growth stimulus in early growth stage was highly correlated with the acceleration of heading is, more or less, correlated with the heading of the late growth stage although we could not conclude the genes for early plant growth stimulus by high temperature is the same genes as the genes for accelerating of heading in the late growth stage of plants.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.6
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• pp.468-472
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• 2001

In order to know the relationship between the accumulated temperature distribution and barley growth characteristics, average, early and late heading years were analyzed. Among 24 year's crop situation test 1976, 1979, 1989, 1990, 1998 were sorted to early heading years and 1977, 1980, 1984, 1996 to late heading years. About $650^{\circ}C$ of accumulated temperature from October to December was enough to get average year's heading date in barley. While 62$0^{\circ}C$ of accumulated temperature were not enough for average heading, 67$0^{\circ}C$ of accumulated temperature accelerated barley heading. 78$0^{\circ}C$ of accumulated temperature from October to February, were enough to get average year's heading date in barley. while $650^{\circ}C$ of accumulated temperature were not enough to, 78$0^{\circ}C$ of accumulated temperature accelerated barley heading. Temperature pattern types in early heading years were distinguished by three types : high temperature type before winter(I), high temperature type in winter-regrowth stage(II), high temperature type in tillering stage(III). On the other hands, temperature pattern types in late heading years were divided to two types : low temperature type in winter-regrowth stage(I), low temperature type in tillering stage(II). Barley heading was mainly influenced by temperature before winter and winter-regrowth stage. Yields of early heading years were higher than that of late heading years and yield was heavily influenced by the number of spikes per square meter.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.1
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• pp.39-46
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• 1996

The experiment was conducted to inxvestigate matter production ability and growth characteristic variation for Italian ryegrass seed of introduced variety and the different seed production time of the next generation in paddy field at Iksan and Kyehwa experiment field from 1987 to 1988. Germination rate is good at seed production of 35 days before and after heading with introducced variety. Also, Early growth before wintering, dead leaf rate and regenerating day is same tendendy. Panicle numbers per hill like that and heading date is for 15~20 days after heading seed is late about three days, but 35 days before and after heading seed is early about one day. Fresh and drymatter yield at the different cutting time shows decrease in 15~25 days after heading seed but 35 days before and after heading seed is same or increase trend, it's notable at Kyehwa paddy field in reclaimed land. In case of feed value according to cutting time differ little against introduced seed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.2
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• pp.9-16
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• 1979

528 Korean land races of barley were examined for IS agronomic traits to determine if any preferential trait associations with early heading and winter hardiness existed in this collection. Eight traits were non-randomly associated with the 1977～'78 cold damage levels, and seven traits were non-randomly associated with heading date. No early heading, least-cold-damaged land race lines were found. However the least-cold-damaged class preferentially associated with mid-early heading land race lines. Ten traits were preferentially associated with the mid-early heading, least-cold-damaged class. The utilization of these associations should increase the probability that genes for winter hardiness will be preserved in the mid-early heading selections from this collection.

• Korean Journal of Plant Resources
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• v.25 no.1
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• pp.142-151
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• 2012

This study was carried out to evaluate genetic variation of early-heading rice (Oryza sativa L. cv. Dongjin 1) lines derived from gamma-ray ($^{60}Co$, 300 Gy) irradiation. The average heading date of the 5 early-heading lines in $M_7$ and $M_8$ generation was faster than that of untreated control as 11 (line ${\gamma}$-2), 10 (line ${\gamma}$-5), 6 (${\gamma}$-1 line), 5 (${\gamma}$-3) and 4 days (line ${\gamma}$-4), respectively. According to ISSR analysis, polymorphic rate of the early-heading lines (from 5.9% to 23.4%) was higher than that of control (4.3%). The result indicates that the gamma-ray promote variation at DNA level. When genetic variations of rps16-trnK region were evaluated by nucleotide analysis, nucleotide length of the rps16-trnK region was 664 bp in all the early-heading lines and control. Out of 5 sites of nucleotide transposition detected in the region, however, 2 sites were appeared only in the early-heading lines.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.1
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• pp.39-46
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• 1985

Heading time was hastened by the combination of seeding time and longday treatment in order to elucidate the effect of early heading on earliness in maturity, vegetative growth and grain yield in five barley varieties and four wheat varieties under field conditions in Suwon, Korea, 1978-79. About 15 days of earliness in heading accelerated only 2 to 6 days in maturity. Furthermore, the duration of grain fill was not much prolonged comparing with the extension of days from heading to maturity, because of the extension of periods from heading to anthesis at lower temperature resulting in somewhat greater final grain weight. Periods from heading to anthesis and from anthesis to maturity were negatively correlated with the air temperature. In early heading, leaf area at 10 days after anthesis and net assimilation rate were much limited, and although leaf area duration got larger, presumably, it could not make up for the reduction of grain yield. Grain yield per plant reduced noticeably in early heading. This was mainly caused by the reduction of spike number and grain number per spike.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.171-171
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• 2022

Effect of temperature during the period of 10 days from transplanting (10 DFT) on the growth and development of rice plants was investigated by transplanting semi-adult seedlings six times from 5 April to 15 May at 10-day interval in the field conditions of 2020 and 2021, with aims to investigate the critical temperature for early transplanting of temperate rice. In the two experimental years, mean temperature for 10 DFT appeared 9.1, 10.5, 11.6, 13.8, 13.9, 16.2, 16.4, 16.7, 17.1, 17.8℃ depending on the transplanting date. Mean temperature of 9.1℃ and 10.5℃ for 10 DFT appeared in the April 5 and April 15 transplants in 2020 showed negative or no effect on the increase of rice growth and acceleration of heading date when compared to those of right after transplanting treatments in the same year. Mean temperature of 11.6℃ for 10 DFT appeared in the April 5 transplant in 2021 demonstrated greater biomass from early to heading stage but the same heading date compared to April 15 transplant, indicating that 11.6℃ for 10 DFT had a positive effect on rice growth but no effect on advanced heading. Both more biomass and advanced heading stage were observed when the mean temperature for 10 DFT was 13.8℃ or higher, compared to those of right after transplanting treatments. These findings indicate that effective 10-DFT mean temperature for rice growth exists between 10.5 and 11.6℃, and that for rice development in terms of heading stage lies between 11.6 and 13.8℃ in natural condition. Further field and indoor studies are suggested to narrow down the critical temperature for early transplanting of temperate rice, which will enable to maximize the crop period in high altitude regions with low temperature.

• Journal of The Korean Society of Grassland and Forage Science
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• v.44 no.3
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• pp.145-156
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• 2024

Due to climate change and the expansion of cultivation areas through the use of reclaimed land, changes in the selection of Italian ryegrass (Lolium multiflorum L.) varieties are anticipated. This study was conducted to compare the growth characteristics before overwintering, productivity, and feed value of eight Italian ryegrass varieties with different maturing stages under the same cultivation conditions. The variety 'Lm4ho', a medium-maturing type, showed superior growth characteristics before overwintering, including plant height, leaf length, and leaf width. The heading date was advanced in all varieties, with a greater degree of advancement observed in varieties with earlier heading dates. When harvested at the heading stage of the early-maturing types, the dry matter yield of the medium-maturing types was not significantly different from that of the early-maturing types. However, when harvested at the heading stage of the medium-maturing types, the dry matter yield was higher than that of the early-maturing types. Specifically, 'Lm4ho' produced 2,518 kg/ha more than 'Kowinearly'. The late-maturing variety IR901 and the medium-maturing varieties 'Lm4ho' and 'Kowinmaster' showed statistically superior dry matter yields. In terms of forage value, including crude protein (CP), total digestible nutrients (TDN), and relative feed value (RFV), the medium- and late-maturing types outperformed the early-maturing types. Notably, 'Lm4ho', 'IR 901', and 'Hwasan 104' were evaluated as suitable varieties for high-quality forage production. These results suggest that medium-maturing varieties may be suitable for double cropping in the central regions due to climate change. We propose that future breeding of Italian ryegrass should expand from focusing on cold tolerance and early-maturing varieties to include medium- and late-maturing varieties that consider both productivity and quality.

• Journal of Crop Science and Biotechnology
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• v.10 no.4
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• pp.243-248
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• 2007

Rice is a facultative short-day plant that flowers in response to reduced day lengths. This study was conducted to identify quantitative trait loci(QTL) for the early heading date(EHD) using H143 line showing extreme EHD compared to other regular cultivars in rice. The japonica H143 was crossed with a japonica cultivar 'Dongjinbyeo' as well as a tongil cultivar 'Milyang23' to measure the inheritance mode of EHD and identify major QTL conferring EHD, respectively. Pooling test revealed that segregation distortion occurred on chromosome 7 and subsequent linkage map was constructed using 10 SSR markers. QTL analysis using Q-gene 3.06 revealed that the EHD trait in H143 was largely controlled by two major QTL, EH7-1 and EH7-2, accounting for more than 40% of genetic variation that were closely related to the previously reported QTL, Hd4 and Hd2, respectively. This result suggests that these two QTL markers may be a useful source for the control of heading date in rice breeding programs.