• 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.68 no.4
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• pp.225-235
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• 2023

Critical temperature for grain filling of three Korean japonica rice varieties was analyzed by late transplantation to induce a low temperature during grain filling period in a field study. The grain filling percentage (GFP) and grain dry weight (GDW) showed a sigmoid development for the first and second transplants in 2020 and first to third transplants in 2021. For the third transplant in 2020 and fourth transplant in 2021, the GFP and GDW reached a peak at 42 days after heading (DAH), and then decreased or remained unchanged. In non-linear regression analyses, 95% of the final GFP and GDW appeared at 49 - 62 DAH for the second transplant in 2020 and at 37 - 46 DAH and 30 - 36 DAH for the second and third transplants in 2021, respectively. At these time points, the critical seven-day moving temperature (7dMovT) was 8.4~9.4℃ for the second transplant in 2020 and 9.4~10.9℃ for the second and third transplants in 2021, depending on the grain filling traits and varieties of rice. The lowest 7dMovT was 8.4 - 8.7℃ in the three varieties. The observed lowest 7-day mean temperature (7dMT) accompanying increases in the GFP and GDW was 9.4 - 10.1℃, depending on the varieties in the third transplant of 2020 and fourth transplant of 2021. In the two transplants mentioned above, the highest 7dMT that showed no increase or decrease in grain filling traits was 8.7 - 9.1℃. The critical temperature for grain filling of japonica rice was 8.4 - 8.7℃ based on the 7dMovT and 9.1 - 9.4℃ based on the 7dMT. The previous 7dMT of 10℃ is recommended to determine the marginal harvest time for safe rice cropping since the temperature was the highest among the lowest temperature that accompanied an increase in grain filling traits.

• 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.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.28 no.2
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• pp.202-210
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• 1983

These experiments were conducted to study the relationship among agronomic traits, varietal variation of grain-filling periods and the effect of environmental conditions on the grain-filling in the ten selected barley cultivars. The varietal variation of grain-filling periods was of significance: Tokak had the similar increment in both greenhouse and field plot, Suweon two row was believed to be an cultivar with short grainfilling period. Cultivars with higher grain-filling rates tended to. have significantly lower ash content. Ash content of a cultivar tended to be lower when grown under favorable condition. At maturity, the time of development of yellow or dark pigment at the crease base could be a possible criterion for physiological maturity determination. However, this requires further study. Average grain-filling period in the different conditions was constant, but varietal differences were 9 days in the greenhouse and 5 days in the field. The grain moisture content was not constant in accordance to both cultivars and growing conditions. Average accelerated days for heading and ripening periods were very constant in comparision with field and vinyl mulching suggests that the selected materials will be useful for genetic study on grain-filling periods. The cultivars and grown conditions with higher accumulated temperature per $100^{\circ}C$ from early grain-filling had larger grain-filling rates and heavier 1000 grain weight. This study showed that if the variation among and within cultivars is to be minimized, the greenhouse and vinyl mulching plots could be useful for genetic study on grain-filling periods in $BC_1$ and $F_2$ segregation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.5
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• pp.425-431
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• 1993

Temperature effects on the grain filling of winter barley(CV. Gangbori, Olbori and Suwon 18) were studied in controlled environments under three day /night temperature regimes (viz. 25/20, 20/15 and 15/10$^{\circ}C ) and at three stages of development, viz. Vegetative, spike development and grain filling stages. Physiological maturity times to the temperature regimes were observed at 53 to 57 days after heading at 15/10$^{\circ}C , 43 to 45 days and 32 to 33 days at 20/15$^{\circ}C and 25/5$0^{\circ}C$, respectively. When plants were grown in 25/20$^{\circ}C during the spike development stages, the number of spikes per plant and grains per spike decreased by 39% and 41% respectively compared with 20/15$^{\circ}C of day / night temperature. The effect of high temperature on grain weight was not significant in all growth phases except post-anthesis where grain weight decreased by 30%. Therefore, the most important temperature effects were round during the spike development stages.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.1
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• pp.1-7
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• 2021

The processing of rice is one of the measures to expand the scope of rice use in response to the decrease in rice consumption. Since the main ingredient of rice processing is rice flour, "rice flour varieties" have been bred with the aim to improve the productivity and quality of rice flour. In order to study the variation in the ripening characteristics of rice flour varieties with respect to temperature, the average temperature after heading date was set at 28℃ (33/23℃), 22℃ (27/17℃), and 18℃ (23/13℃) inside the phytotron. We used Saenuri as non-glutinous rice variety, Seolgaeng as soft-type rice flour variety, and Baromi2 as powdered rice flour variety. At high temperatures (28℃), the grain weight of Baromi2 decreased by 21%. Its starch content also decreased by more than 10%, which was significantly lower than that of Saenuri and Seolgaeng. At low temperatures (18℃), the grain weight and starch content slightly increased or were similar in all varieties. An analysis of changes in the grain weight due to effective accumulated temperature through the sigmoid function showed that the velocity of grain-filling slowed significantly when Baromi2 was exposed to low temperature during the ripening stage compared to the other varieties. Therefore, the transplanting time of Baromi2 should be delayed to avoid high temperatures during the ripening stage. However, because the ripening period is not properly secured under low temperature conditions, grain filling may not be sufficient.

• Journal of Powder Materials
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• v.6 no.1
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• pp.81-87
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• 1999

Based on the pore filling theory, the microstructure evolution during liquid-phase sintering has been analyzed in terms of interrelationship between average grain size and relative density. For constant liquid volume fraction, the microsturucture trajectories reduced to a single curve in a grain size(x)-density(y) map, regardless of grain growth constant. The slope of curves in the map was inversely proportional to average pore size, while it increased fapidly with liquid volume fraction. Increase in pore volume fraction retarded the densification considerably, but showed marginal effect on the slope. The activation energy of densification was predicted to be the same as that of grain growth as long as the liquid volume fraction is constant for any temperature range studied. The present analyses on microstricture evolution may demonstrate the usefulness of pore filling theory and provide a guideline for process optimization of liquid-phase sintering.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.124-124
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• 2022

Wheat (Triticum aestivum L.) is the major staple foods and is in increasing demand in the world. The elevated temperature due to changes in climate and environmental conditions is a major factor affecting wheat development and grain quality. The optimal temperature range for winter wheat is between 15~25℃, it is necessary to study the physiological characteristic of wheat according to the elevated temperature. This study presents the effect of elevated temperature on the yield and quality of two Korean bread wheat (Baekkang and Jokyoung) in a temperature gradient tunnel (TGT). Two bread wheat cultivars were grown in TGT at four different temperature conditions, i.e. TO control (near ambient temperature), T1 control+1℃, T2 control+2℃, T3 control+3℃. The period from sowing to heading stage has accelerated, while the growth properties including culm length, spike length and number of spike, have not changed by elevated temperature. On the contrary, the number of grains per spike and grain yield was reduced under T3 condition compared with that of control condition. In addition, the. The grain filling rate and grain maturity also accelerated by elevated temperature (T3). The elevating temperature has led to increasing protein and gluten contents, whereas causing reduction of total starch contents. These results are consistent with reduced expression of starch synthesis genes and increased gliadin synthesis or gluten metabolism genes during late grain filling period. Taken together, our results suggest that the elevated temperature (T3) leads to reduction in grain yield regulating number of grains/spike, whereas increasing the gluten content by regulating the expression of starch and gliadin-related genes or gluten metabolism process genes expression. Our results should be provide a useful physiological information for the heat stress response of wheat.

• Plant Breeding and Biotechnology
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• v.6 no.4
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• pp.363-380
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• 2018

Wheat is frequently exposed to high temperature during anthesis and ripening period, which resulted in yield loss and detrimental end-use-quality. The transcriptome analysis of wheat under high temperature stress during the early stage of the grain filling period was undertaken. Three expression patterns of differentially expressed genes (DEGs) during grain filling period were identified. The DEGs of seed storage protein and starch-branching enzyme showed continuous increases in their expressions during high temperature stress, as well as during the recovery period. The activities of the enzymes responsible for the elimination of antioxidants were significantly affected by exposure to high temperature stress. Only the WAS-2 family genes showed increased transcription levels under high temperature stress in dehulled spikelets. The relative transcription levels for sub-genome specific WAS-2 genes suggested that WAS-2 genes reacted with over-expression under high temperature stress and decreased back to normal expression during recovery. We propose the role of WAS-2 as a protective mechanism during the stage of grain development under high temperature in spikelets.