• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.172-181
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• 2023

In order to raise the self-sufficiency rate of domestic forage and obtain informations necessary for production of high-quality winter forage, forage yield and feeding value were analyzed in the above-ground parts of a winter wheat 'Cheongwoo' harvested at five different growth stages, and the appropriate harvest time was determined. The yield increased until 30 days after heading, and then decreased afterwards. The proportion of spike in the above-ground part was less than 40% until 30 days after heading, but increased to more than 60% afterward. At 30 days after heading, the protein content and relative feed value (RFV) also reached peaks, while acid detergent fiber (ADF) and neutral detergent fiber (NDF) were low. The mineral nutrient contents are within the standard range required for feeding ruminant livestock or do not exceed the maximum allowable level. Therefore, the best time to harvest above-ground parts of a winter wheat 'Cheongwoo' for use as a forage for feeding ruminant livestock is around 30 days after heading, when considering forage yield and feed values. As a result it would match well in time with the transplantation of rice seedlings or the sowing of rice-alternative field crops in the double cropping system.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.1
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• pp.22-26
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• 2014

This research was implemented to investigate pre-harvest sprouting characteristics in two Korean rice cultivars, Shindongjin (SDJ) and Hopum (HP). The panicles of both varieties were sampled after 15 days after heading (DAH) to 60 DAH at intervals of 5 days. As soon as sampled, the panicles were imbibed in water for 14 days at $25^{\circ}C$ to determine the vigor and germination ability of seeds according to location on panicle. To investigate the cause of non-germination of seeds in panicles, tetrazolium test and dormancy breaking were performed. The preharvest sprouting of HP started at 20 DAH while that of SDJ began at 30 DAH. The germination of seeds located in high rank branches within a panicle and the terminal seeds within a branch were earlier and faster and the germination patterns were same in both cultivars. The times at more than 50% of germination in a panicle were 35 DAH (57.0%) in HP and 45 DAH (56.8%) in SDJ. Preharvest sprouting was more than 80% at 50 DAH (82.6% of HP, 92.3% of SDJ) and more than 99% at 60 DAH (99.5%, 99.4%, HP and SDJ). These results indicated that the rate of PHS in a panicle increased with accumulation of the days after heading. The cause of non-germinated seeds at 15-25 DAH in panicle was immature embryo. After 30 DAH, however, when the non-germinated seeds were hulled, they started to germinate due to dormancy breaking, in which the germination percentage was higher in SDJ than HP. In conclusion, the pre-harvest sprouting varied according to days after heading, the seed position on panicle, and the dormancy intensity of varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.20
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• pp.134-141
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• 1975

The response to short day treatment in rice plant has been more sensitive along the progress of the growth until 35 days after seeding. The minimum number of short day cycles needed for heading of photoperiod-sensitive rice variety, BPI 76, were 29, 12 and 11 when treatment was started from seeding, 30 days and 35 or more days after seeding respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.4
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• pp.403-407
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• 1986

The rice leaf color, which was one of main factors to determine application time of fertilizers, was analyzed in visible region, while the distinction of photosynthetic pigments controlling the rice leaf color was separated by T.L.C. The light absorption peaks of ethyl ether extracts of rice leaf blades were occurred in 413, 432, 453 and 662nm. Especially, the maximal light absorption was 432nm in blue and 662nm in red region. The both light absorption ratios (blue to red region) was not greatly different among rice ecotypes, whereas decreasing tendency in increased fertilization was observed. There was a significant negative correlation between the both light absorption ratios and the values of color chart, and the content of chlorophyll in rice leaf blades. The composition ratio of chorophyll was larger than that of carotenoid at heading stage, and the carotenoid was larger than the chlorophyll at 30 days after heading. The composition ratio of chlorophyll among photosynthetic pigments according to rice ecotypes, Japonica x Indica cultivars were larger than Japonica cultivars at heading stage, and Japonica cultivars were larger than Japonica x Indica cultivars at 30 days after heading, while carotene was vice versa.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.1
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• pp.93-103
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• 1992

Experiments were conducted in the research field of the Wheat and Barley Research Institute with three barley cultivars, Olbori, Kangbori and Suwon 18, which showed different growth characteristics. The highest rates of daily dry matter accumulation in grains were 1.03 1.94 mg / grain / day in early and optimum sowings and 0.88 1.88 mg / grain / day in late sowings, which occurred around 20～30 days after heading in early and optimum sowings and 15～20 days after heading in late sowings. Grains reached their maximum weight by 40 days after heading in early and optimum sowings and 35 days after heading in late sowings. Total sugar content in grains followed a pattern of linear increase immediately after heading, but it started to decrease around 20 days after heading. On the other hand, starch content continued to increase until maturity. The contents of both components were high in the order of ＆apos;Olbori＆apos; ＆gt; ＆apos;Kangbori＆apos; ＆gt; ＆apos;Suwon 18＆apos;, but they did not respond in a regular pattern to different sowings. 1,000 grain weight showed highly significant positive correlation(r=0.767$^{**}$) with the duration of grain growth, but it had negative correlations with the average (r=-0.548$^{**}$) or the sum (r=-0.595$^{**}$) of post-anthesis daily mean temperature.ature.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.6
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• pp.486-491
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• 2002

Spikelet number and its components of rice plant are closely associated with nitrogen accumulation and biomass production during panicle formation stage. To elucidate this relationship and also compare the differences of the sink formation efficiency among cultivars, spikelet number, its components, nitrogen content, nonstructural carbohydrate content, and plant dry matter were investigated under 5 nitrogen levels with two split application methods and shading treatments by using three rice varieties. The nitrogen amount in shoot at panicle initiation stage and at 15 days after panicle initiation showed significant positive correlation with primary rachis branches per square meter, and that at 15 days after panicle initiation and at heading stage with secondary rachis branches per square meter, Primary and secondary rachis branches per square meter showed positive significant correlation with the shoot dry weight at panicle initiation stage and at 15 days after panicle initiation stage, respectively, The amount of degenerated secondary rachis branches and spikelets per square meter showed significant negative correlation with the dry weight and nonstructural carbohydrate increase of stem during 15days after panicle initiation, and the contents of nonstructural carbohydrate at 15 days after panicle initiation. Spikelets per unit area showed significant positive correlation with nitrogen amount in shoot and shoot dry weight at heading stage. The sink formation efficiency expressed as the spikelet number produced by the unit amount of nitrogen in shoot at heading stage was higher in Nampoongbyeo than Choocheongbyeo and Hwaseongbyeo. Sink formation efficiency was negatively correlated with the dry weight increase of shoot and stem during reproductive stage. but not significantly with that of leaf in all varieties. Sink formation efficiency was not significantly correlated with nonstructural carbohydrate, but was significantly negatively correlated with structural carbohydrate increase during reproductive stage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.2
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• pp.137-143
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• 2012

This study was conducted to investigate the yield and greenness of "Nogwonchalbyeo" on the basis of different date of transplanting and harvesting. Delay in heading was observed in the plants transplanted later but no effect on heading was observed due to different levels of nitrogen fertilizer. Percentage of green color in dehusked rice was higher in the grains of rice transplanted on 10th June. An increasing trend was observed in the yield with the delay in the date of transplanting, maximum yield was observed in the rice planted on 10th June but a decrease in yield was recorded if transplanted after 15th June. Similarly, yield also increase as the days for harvesting increased until 37 days after heading but beyond 37 days decreasing trend was observed in yield. Based on the above findings it can be suggested that 4~6 June and 9kg/10a are the optimum dates of transplanting and amount of nitrogen while 3 5~37 days after heading is the best time for harvesting of "Nogwonchalbyeo".

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.4
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• pp.439-444
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• 1983

Effects of temperature and soil moisture on the growth and grain-filling of two wheat cultivars were investigated. Two levels of temperature; day 3$0^{\circ}C$/night $25^{\circ}C$ and day 2$0^{\circ}C$/night 15$^{\circ}C$ and two levels of soil moisture; stressed (45-50% of F.C.) and non-5tressed (50-60% of F.C.) were imposed in the green house from heading date to the maturity and grain weight, chlorophyll content of flag leaf and leaf area index(LAI) were observed at weekly interval. Grain maturation was faster in the high temperature than those in the lower temperature. Chlorophyll content of flag leaf and LAI decreased rapidly in the high temperature and chlorophylls disappeared at the 20 days after heading. In lower temperature condition, slower decrements were shown in chlorophyll content and it remained until 45 days after heading. Grain weights in the high and optimum temperature conditions reached to maximum values at 29 days and 45 days after heading, respectively. Differences of grain weight and chlorophyll content of flag leaf were not significant between stressed and non-5tressed soil moisture condition.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.3
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• pp.195-202
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• 1993

This experiment was carried out to investigate the eft'ects of different seeding dates on the agronomic characteristics, forage yield and quality of fall sown cats(Avena sativa L.). The experiment was conducted at the forage experimental field, Seoul National University. Suweon in 1990. The results obtained are summarized as follows; 1. Present data indicated that plant and ear heights were decreased as the seeding date was delayed. Dry matter accumulation was increased due to the higher plant and ear heights. 1. When oats was seeded on August 20. the first heading and 50% heading dates were recorded on October 4 and 15, respectively. And when oats was seeded on August 25. the first heading and 5 0'!4 heading dates were observed on October 13 and 18. respectively. As seeding date was delayed for one day. the heading date was delayed for two days. 3. The dry mattcr percentage of oats seeded on August 20 was 20.1%, but that of oats seeded after August 10 was 15.1 to 16.7%. 4. According to the contents of CP. ADF and NDF, oats seeded on August 20 and 25 was evaluated to be the 3rd or 4th grade hay. and the other oats sceded after August 15 was recorded the 2nd or 3rd grade hay as proposed by AFGC. 5. There are no significant dry matter yield differences among the seeding dates of oats such as August 20, 25 and 30. but a significant yield difference was recorded between oats seeded in August and September. The same trend as the dry matter yield was observed in in vitro digestible dry matter and crude protein yields of oats seeded in August and September. According to the results. early seeding of early matuaring oats may be a better option than late seeding after August 30 for silage or hay production following silage corn harvest in the middle northern area of Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.6
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• pp.487-498
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• 1992

To study the effects of different nursing methods and transplanting on the growth of rice plant (Oriza sativa L.) in southern region of Korea, Kumo-byeo, Palgong-byeo and Dongjinbyeo were transplanted from April 20 to July 20 at an interval of 15 days with 8 days old seedling (infant seedling) and 25 days old box-seedling for machine transplanting, and 45 days old conventional seedling. Threshold transplanting date in southern region of Korea were June 26 for 8 days old seedling, July 1 for 25 days old seedling and] July 11 for 45 days old seedling for Kumo-byeo, and June 21, June 30, July 10 for Palgong-byeo, June 10, June 24, July 5 for Dongjin-byeo, respectively. Yield has no uniform tendency according to the transplanting date. However, yield were greater in the order of 8 days old seedling >25 days old seedling> 45 days old seedling in Kuma-byeo and 25 days old seedling (equation omitted)8 days old seedling (equation omitted)45 days old seedling in Palgong-byeo, 45 days old seedling(equation omitted)25 days old seedling(equation omitted) 8 days old seedling in Dongjin-byeo. The optimum accumulated air temperature during yield productive stage around heading (40 days from 10 days before heading to 30 days after heading) for high yield were 1,003$^{\circ}C$ for 8 days old seedling, 1,014$^{\circ}C$ for 25 days old seedling and 1,027$^{\circ}C$ for 45 days old seedling in Kumo-byeo. And they were 1,018$^{\circ}C$, 1,015$^{\circ}C$, 1,086$^{\circ}C$ in Palgong-byeo and 998$^{\circ}C$, 984$^{\circ}C$, 949$^{\circ}C$ in Dongjin-byeo, respectively. Earlier transplanting with 8 days old seedling showed higher ratio of broken rice and green kerneled rice in Kuma-byeo, and late transplanting after July 5 showed significant high rate of green kerneled rice. Palgong-byeo and Dongjin-byeo also showed high rate of green kerneled rice at transplanting after July 5.