• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.2
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• pp.120-130
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• 2018

Improvement in rice grain yield has been approached by means of genetic amendment, cultural management, and environmental adaptation. Subjecting the plant during the grain filling period to an appropriate environment plays a key role in achieving a high grain yield in temperate rice. Field experiments were conducted for two consecutive years with two planting times to assess the relations among grain filling traits, loss of leaf activity during the ripening period, and the grain yield of temperate japonica rice with wide environmental variation. Higher grain yields were attained in 2017 than in 2016 and with late planting than with early planting. The high grain yield accompanied a comparatively lesser increase in grain weight at the early filling stage but more gain in grain weight occurred during the late filling stage. Final grain weight correlated positively with grain filling duration but negatively with grain filling rate. Extended grain filling duration was associated with higher cumulative temperature and cumulative solar radiation for an effective grain filling period. The reduction in SPAD value ${\times}$ leaf dry weight from heading to harvest significantly correlated with final grain dry weight in a positive manner. No significant relation was found between grain filling duration and the decrease in SPAD value ${\times}$ leaf dry weight during the grain filling period. The results suggest that grain filling duration and loss of leaf activity during ripening independently contribute to environmentally induced yield improvement in temperate japonica rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.368-373
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• 1983

To study the grain development and quality during wheat grain-filling under different sowing date and region, the experiments were conducted from 1978 to 1979. The grain weight at the early grain-filling stage in Suweon was heavier than in Gwangju, but the weight at the late grain-filling stage was reversed. The ranges of the physiological maturing period in the optimal sowing for 2 years were from 43 to 49 days in Suweon and from 44 to 51 days in Gwangju. These showed the tendency of lengthened grain-filling periods in southern region, and the periods were 1-4 days longer in optimal sowing than those in late sowing. Wheat grain quality was affected significantly by environmental conditions. The milling rates were increased in southern region where the plumpness of grain was better, the protein content and sedimentation value were higher in northern region where the temperature during grain-filling was high.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.1
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• pp.32-37
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• 2000

The in vitro culture of rice panicles is a culturing technique only panicle without other organs in culture solution containing organic substance, so that would be useful to study how assimilate supply affects grain development and maturation. To find the optimum stage for in vitro culture, rice panicles grown in greenhouse were sampled periodically after anthesis and cultured in nutrient medium. The panicles older than 1 weeks after anthesis had produced normal grains. Grain-filling was apparently dependent upon sucrose concentration (8-12 %) in medium, but not affected by nitrogen concentration supplied with glutamine. As far as rice panicle was supplied with sucrose and N in nutrient medium, grains continued accumulation of dry matter and maturation regardless to light condition. Considerably, grain-filling was improved when panicles were positioned horizontally inside flask, so that each grain was partially submerged to nutrient medium.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.1
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• pp.34-40
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• 1991

The study aimed to investigate the relationship between the rates of leaf senescence and photosynthate translocation at post-anthesis. Seven barley varieties were observed at Suweon in 1988-89. The varieties differed significantly in the number of leaves survived and the rate of photosynthate transolcation with the progress of grain filling. The rate of grain filling was higher in the fast leaf sene-scencing varieties than the slow senescencing ones. There was a close coincidence between the rates of grain filling and $\^$14/c translocation into grains. Photosynthesis was higher in the fast leaf senescencing varieties at early stage of grain filling, but the reverse phenomenon was observed at the late stage of grain filling. The grain yield of fast senescencing varieties was higher than that of slow ones.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.216-223
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• 2003

This study was conducted to investigate the varietal differences in leaf senescence and the relationship between leaf senescence and photosynthesis during ripening stage of rice. During grain filling period, leaf senescence was evaluated by SPAD readings (an indirect indicator of chlorophyll content) for 3 rice varieties (SNU-SG1, Hwaseongbyeo, Nampungbyeo). SPAD value of flag leaf and 2nd leaf of SNU-SG1 were much higher than the other varieties and the leaves of SNU-SG1 also showed a tendency of delayed senescence as compared to the other varieties. Photosynthesis at light saturation (Pmax) of flag, 2nd and 3rd leaf in SNU-SG1 during grain filling period were much higher than Hwaseongbyeo and Nampungbyeo. The Pmax of the flag leaf in SNU-SG1 was especially higher over 20% than the other varieties. It was due to its higher mesophyll conductance and stomatal conductance as compared to the other varieties. Pmax, stomatal conductance and mesophyll conductance had positive correlation with SPAD value and nitrogen concentration of leaves. In conclusion, the stay green characteristics of SNU-SG1 would contribute to increasing the grain yield through the improved photosynthesis during grain filling.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.3
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• pp.273-281
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• 2015

Relationship between grain quality-related traits and daily mean temperature/sunshine hours during grain filling stage was analyzed using eleven high quality rice varieties at 24 experimental sites through eight provinces of Korea in 2013~2014. In the data set pooled across varieties, experimental sites and years, grain quality-related traits such as percentage of head rice (PHR), head rice yield (HRY), protein in milled rice (PRO) and Toyo Mido Meter glossiness value (TGV) were higher at the temperature lower than $22.6^{\circ}C$ for 40 days after flowering (DAF), which was optimum for percentage of grain filling in this study. Optimum sunshine hours for 40 DAF were $6.0{\sim}6.1\;hr\;d^{-1}$when considered PHR, HRY and TGV. PRO was associated with daily mean temperature and sunshine hours for 40 DAF in more varieties than the other traits. PRO was closely correlated with daily mean temperature during early filling stage and sunshine hours during early to mid filling stage, compared to other stages during grain filling. It is concluded that general trend in the variation of grain quality-related traits could be explained by the changes in daily mean temperature and sunshine hours during grain filling. In addition, climate conditions during early grain filling stage played important roles to enhance grain quality.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.224-231
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• 2003

This study was conducted to investigate the varietal differences in leaf senescence during ripening stage and its relation to grain yield of rice. During grain filling period leaf senescence was evaluated by SPAD readings (an indirect indicator of chlorophyll content) for 74 varieties including local, improved domestic, and introduced varieties in the field condition. Leaf senescence was varied greatly among 74 varieties. Jodongji and Dadajo known as local rice varieties had significantly lower SPAD value than the other varieties and became senescent rapidly. However, SPAD value of the flag leaf and 2nd leaf of SNU-SG1 were much higher than the other varieties and leaves of SNU-SG1 also showed a tendency of delayed senescence compared to the other varieties. There were significantly positive correlation between cumulated SPAD value of upper leaf(flag leaf and 2nd leaf) during 35 days after heading and grain yield divided by sunshine hour during 40 days of grain filling and compensated for temperature effect, and cumulated SPAD value of the 4th leaf showed negative correlation with the yield. That is, the delayed senescence of the upper leaves and the rapid senescence of lower leaves were positively associated with grain yield increase.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.2
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• pp.146-152
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• 2015

Early-maturing Korean Japonica cultivars and Jungmo1024 were used as plant materials to evaluate hightemperature tolerance during grain filling stage. National Institute of Crop Science (NICS) in Korea developed Jungmo1024, a mutant line from Namil (wild type) treated by using sodium azide (SA) as mutagen. To evaluate high-temperature tolerance, all cultivars were exposed to high-temperature (day $31.5{\pm}2.5^{\circ}C$/ night $27.5{\pm}1.3^{\circ}C$) and ordinary temperature (day $27.5{\pm}1.8^{\circ}C$/ night $24.7{\pm}1.6^{\circ}C$) during grain filling stage. In these conditions, we performed compared evaluation of grain shape such as length and width and grain quality by using a 1625 Cervitec grain inspector. High-temperature during grain filling stage caused decrease of grain shape. In grain shape such as length and width, the decrease rate of width (average 6.3%) was higher than the decrease rate of length (average 1.3%). Hence, high-temperature affected width of grain than length of grain. In addition, high-temperature showed a decided difference in rate of head rice between ordinary temperature (average 76.3%) and high-temperature (average 13.3%).As a result, Taebong, Ungwang, Manan, and Jungmo1024 seemed relatively a decent high-temperature tolerance than other cultivars. Especially, Jungmo1024 seemed remarkable rate of head rice (average $34.4{\pm}6.2%$) than other cultivars under high-temperature. It is considered that a genetic trait of Jungmo1024 can be useful to improve breeding for high-temperature tolerance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.3
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• pp.266-272
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• 2015

High temperature impairs rice grain yield and quality. To understand the effect of high temperature on leaf physiological activity and grain filling, two cultivars of rice that Dongan and Ilpum were exposed to high temperature during ripening stage. Grain filling rate, perfect grain ratio and grain weight of high temperature ($27^{\circ}C{\pm}4^{\circ}C$) treated both rice cultivars were decreased than those of control temperature ($22^{\circ}C{\pm}4^{\circ}C$) treated. The reduction rates of grain filling ratio, perfect grain ratio and grain weight of high temperature treated to control treated rice were higher in Ilpum than Dongan. Chlorophyll contents of rice leaves under high temperature at early ripening stage were higher than those of control temperature, but those were slowly decreased with no difference between temperature treatment since at mid ripening stage. Although chlorophyll a/b ratio under high temperature was decreased from heading to 15 days after heading, that was gradually increased since 15 days after heading. Protein concentrations of rice leaves for ripening stage was a similar pattern with chlorophyll changes. The rate of photosynthesis at 14 days after heading under high temperature was higher than those of control temperature, but there was no difference at those of 7 and 34 days after heading between two temperature treatment. Free sugars under high temperature treated leaves were lower than control temperature. Consequently, these results exhibit that high temperature accelerate leaf physiological activity as chlorophyll synthesis and photosynthesis rate unlike the deterioration of grain filling.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.1
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• pp.58-75
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• 1983

The effects of air temperature on the grain filling stage of indica-japonica crosses were studied in artificial temperature-controlled cabinets, using Indica-Japonica crosses (Suweon 264, Suweon 258 and Milyang 29), Indica IR 36 and Lengkwang) and a Japonica rice (Jinheung). The optimum temperature to achieve maximum grain weight during the grain-filling stage was $26/18^{\circ}C$ for all varieties. Within the temperature range of 13 to $28^{\circ}C$, the grain filling period was shorter as the temperature was increased. At the highest temperature $(32/24^{\circ}C)$ the upper-position grains ("special spikelets") of IR 36 required 13days after flowering to reach the maximum weight, in Jinheung 23 days, in indica-japonica varieties (Suweon 264, Suweon 258, and MiIyang 29) 18 days, and in Lengkwang, 23 days. In the case of Lengkwang, at $32/24, \;29/21^{\circ}C$ and $26/18^{\circ}C$temperature range the upper-position grain also required same 23 days after flowering to reach the maximum weight. At the lowest temperature range of $17/9^{\circ}C$, Jinheung required 68 days and Lengkwang 53 days after flowering to reach maximum grain weight. The whole panicle took 10 to 15 days later than the special spikelets to reach the maximum weight. At lower-than-optimum temperature range $(l7/9^{\circ}C\;and\;20/12^{\circ}C)$, all IR 36 plant died within 15 days after flowering. In the case of indica-japonica varieties all plants died within 15 days only at $17/9^{\circ}C$. There were more chalky grains when the temperature was higher and lower than optimum. The highest and lowest temperature range produced dead rice (black and dark red rice). Lower than optimum temperature ranges $(17/9^{\circ}C\;and\;20/12^{\circ}C)$ affected grain quality (length, width and depth) at these temperature ranges, grains were shorter, narrower, and thinner than grains at the optimum temperature of $26/18^{\circ}C$. With regared and the effects of temperature on frequency of grain weight at grain filling stage of indica variety IR 36, the highest $(32/24^{\circ}C)$ and lowest $(23/15^{\circ}C)$ temperature ranges matched the frequency of grain weight curves. In Japonica variety Jinheung, at the three temperature ranges, that is, lowest $(17/9^{\circ}C)$ highest $(32/24^{\circ}C)$ and optimum $(26/18^{\circ}C)$, the frequency of grain weight curve showed very different patterns, In the case of indica-japonica variety Suweon 258, the frequency of grain weight curve was midway between that of IR 36 and Jinheung. Jinheung.