• 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.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.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.72-80
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• 1999

The study was conducted to establish the safe cropping season for direct- seeding on flooded paddy by the analysis of meteorological data(l973~1992, 20 years) from Korea Meteorological Administration. The critical date for early seeding(CDES) at direct- seeding culture on flooded paddy was decided by the appearance date of daily mean air temperature(DMAT) of 15$^{\circ}C$. The optimum heading date(OHD) was the first day when 22$^{\circ}C$ of daily mean air temperature could be kept for 40 days of ripening period after heading, and the critical date of late heading for safe ripening(CDHR) was the last day when 19$^{\circ}C$ of daily mean air temperature could be kept for 40 days after heading. The optimum seeding date(OSD) and the critical date for late seeding(CDLS) could be decided by the accumulated temperature from OHD and CDHR to the appearance dates of necessary temperatures for early, intermediate, and intermediately late maturing varieties. This results can be used for the determination of the safe cropping season of direct-seeding on flooded paddy in each agroclimatic zone. For instance, the OSD appearance date for early maturing variety in Suwon region appeared to be May 11~20 and the CDLS appearance date was May 31~June 7.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.2
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• pp.97-106
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• 1991

Two dimensional non-parametric model using daily mean temperature and daylength as predictor variables was established and daily developmental rates (DVR) for the period of seedling emergence to heading were estimated for 26 rice cultivars by using data from field direct seeding dates and short-day treatments experiment carried out at experimental farm of Seoul National University in 1990. Three existing parametric models were tested for the comparision of predictability with non-parametric model. The non-parametric model was found to be superior to parametric models in predicting heading date. The developmetal indice(DVI) at heading date, cummulative DVR's from seedling emergence showed 0.5 to 2.2 percent of coefficient of variations. The non-parametric model revealed errors of 0 to three days in 11 varieties when applied to data independent of those used in estimating DVR.

• Proceedings of the Korean Society of Potoscience Conference
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• 2006.06a
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• pp.66-66
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• 2006

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.3
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• pp.259-267
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• 2010

This study was performed at Rice and Winter Cereal Crops Department of NICS during 2007 and 2008 to investigate the characteristics of rice leaf emergence and to obtain basic data which can be used for rice growth simulation model by which we can forecast rice growth stage and heading date accurately under different cultivars, transplanting date, and climatic conditions. To confirm leaf emergence rate according to rice maturing ecotype, we surveyed the leaf emergence rate and heading date of Unkwangbyeo, Hwayoungbyeo and Nampyeongbyeo which are early maturing, medium maturing and medium-late maturing cultivars, respectively, according to seedling raising duration and transplanting time. When seedling duration was 15 days, the growth duration between transplanting time and completion of flag leaf emergence on main culm were 51.5~78.3 days in Unkwangbyeo, 55.3~87.9 days in Hwayoungbyeo and 58.4~98.4 days in Nampyeongbyeo, respectively. When seedling duration was 30 days, they were 50.1~75.5 days in Unkwangbyeo, 52.4~84.7 days in Hwayoungbyeo and 56.4~93.8 days in Nampyeongbyeo, respectively. As transplanting time delayed, the emerged leaf number after transplanting decreased in all rice cultivars. The cumulative temperature between transplanting time to completion of flag leaf elongation on main culm were $1,281^{\circ}C{\sim}1,650^{\circ}C$ in Unkwangbyeo, $1,344^{\circ}C{\sim}1,891^{\circ}C$ in Hwayoungbyeo and $1,454^{\circ}C{\sim}2,173^{\circ}C$ in Nampyeongbyeo, respectively. Leaf emergence rate on main culm were precisely represented by equation, y = $y_0$ + a / [1 + exp( - (x - $x_0$) / b)]^c, when we used daily mean temperature as variable.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.2
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• pp.127-136
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• 2019

Sweet sorghum (Sorghum bicolor L. Moench), compared to traditional crops, has been evaluated as a useful crop with high adaptability to the environment and various uses, but cultivation has not expanded owing to a lack of related research and information in Korea. This study was conducted to estimate heading date in 'Chorong' sweet sorghum based on climate data of the last 30 years (1989 - 2018) from six regions (Jeonju, Buan, Jeongup, Imsil, Namwon, and Jangsu) in Jellabuk Province. In addition, we compared the growth and quality factors by sowing date (April 10, April 25, May 10, May 25, June 10, June 25, and July 10) in 2018. Days from sowing to heading (DSH) increased to 107, 96, 83, 70, 59, 64, and 65 days in order of the sowing dates, respectively, and the average was 77.7 days. The effective accumulated temperature for heading date was $1,120.3^{\circ}C$. The mean annual temperature was the highest in Jeonju, followed in descending order by Jeongup, Buan, Namwon, Imsil, and Jangsu. The DSH based on effective accumulated temperature gradually decreased in all sowing date treatments in the six regions during the last 30 years. DSH of the six regions showed a negative relationship with mean temperature (sowing date to heading date) and predicted DSH ($R^2=0.9987**$) calculated by mean temperature was explained with a probability of 89% of observed DSH in 2017 and 2018. At harvest, fresh stem weight and soluble solids content were higher in the April and July sowings, but sugar content was higher in the May 10 ($3.4Mg{\cdot}ha^{-1}$) and May 25 ($3.1Mg{\cdot}ha^{-1}$) sowings. Overall, the April and July sowings were of low quality and yield, and there is a risk of frost damage; thus, we found May sowings to be the most effective. Additionally, sowing dates must be considered in terms of proper harvest stage, harvesting target (juice or grain), cultivation altitude, and microclimate.

• Korean Journal of Agricultural Science
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• v.2 no.2
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• pp.331-339
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• 1975

This experiment was carried out to obtain some imformations about the ecological variations of the heading time of the newly breeded Indica x Japonica varieties/pedigrees according to the seasonal changes of the seeding date. day length and temperature. The results obtained are summarized as follows; 1) At all varieties. days to heading showed a straight reduction according as the seeding time was delayed. 2) At the group of Japonica varieties. the days to heading of early maturing varieties were much shortened and that of medium or late maturing varieties were little or not shortened under high temperature condition but at the group of Indica ${\times}$ Japonica va rieties/pedigrees. days to heading were significantly elongated under high temerature condition. 3) At the group of Japonica varieties. the effect of the short day condition on the days to heading was significantly high at the medium and the late maturing varieties than at the early maturing varieties. however. the short day effect on the reduction of days to heading was not related with the earlyness of each varieties at the group of Indica ${\times}$ Japonica varieties/pedigrees. 4) Days to heading of all varieties under the high temperature condition were longer than that under the ordinary culture. On the other hand, the days to heading of Japonica varieties under the short day treatment were shorter than the days to heading of ordinary culture but at the group of Indica x Japonica varieties/pedigrees. the days to heading under the short day treatment were longer than ordinary culture. 5) At both varieties groups. the days to heading at each seeding time were significantly correlated with days to heading at ordinary cultivation. fl) At the group of Japonica varieties. relatively high correlation(p=0.1) was recognized between the days to heading by delay of seeding time, but at the group of Indica ${\times}$ Japonicava rieties/pedigrees, correlation between the ordinary heading date and the shortening rate of days to heading was very low.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.3
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• pp.207-213
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• 2010

Changes of heading response and leaf production of winter cereals according to cultivar and sowing date in spring, were investigated in Suwon Korea during three years from 2007 to 2009 to obtain information on use as spring living mulch of winter cereals for weed suppression without herbicide in environment-friendly crop production. Rye showed variation among cultivar in heading response according to sowing date, which means that cultivar selection for living mulch is important in rye. Cultivar Prima and Wintergreen had not headed in sowing during March with low soil temperature in contrast to cultivar Koolgrazer and Gokwoo which had headed somewhat even until sowing in early May with relative high soil temperature. Barley and wheat showed distinct characteristics in heading response between sowing before and after early April compared to rye. Leaf production for soil covering was higher in barley than wheat, and cultivar Mirak than Ol within barley in 2007, respectively. Leaf production were not different much among rye cultivar in sowing during early or mid April, but it was different in sowing after mid April indicating that winter cereal cultivar with high leaf production could be selected in late sowing. It is thought that rye cultivar Duru was the most proper cultivar for spring living mulch in the point of high leaf production in addition to low heading in sowing after March.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.6
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• pp.366-369
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• 2000

This study was conducted to determine the effect of seeding date on the days and the accumulated temperatures to development stages, leaf emergence, and yield in spring-planted barley. Two barley varieties, Sacheon #6 in spring type (growth habit I) and Saechalssalbori in winter type (growth habit IV), were seeded on four seeding date, Feb. 23, March 4, March 13, and March 24. Growth periods to emergence, heading and maturity were shorten when seeding dates were delayed, except for the heading date of Saechalssalbori (winter type barley)at the later seeding date. The rate of leaf emergence was 0.1915 in a day, and was slightly high when seeding was delayed. The accumulated temperatures were 111-142$^{\circ}C$ for emergence, 683-756$^{\circ}C$ for heading, and 1274-1326$^{\circ}C$ for maturity. In general, the accumulated temperature to heading was higher in Saechalssalbori than in Sacheon #6 because the winter growth habit of Saechalssalbori was not removed perfectly, One-thousand grain weight and yield were reduced by delayed seeding. In order to reduce the yield when barley were planted in spying, it is desirable to select the spring type varieties, and to plant them as early as possible.