• Korean Journal of Soil Science and Fertilizer
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• v.5 no.2
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• pp.75-82
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• 1972

The proposed hypothesis that the effects of climatic factors during ripening period (from 10 days before heading to 30 days after heading) on ripened grain ratio are equal on the level of canopy and on the level of tiller in that canopy of rice plant appeared to be agreeable. The followings were found according to the analysis of ripening structure at tiller level. 1. The optimum ripening temperature (mean air temperature during ripening period) was $21^{\circ}C$ for Jinheung and $22^{\circ}C$ for IR667-Suwon 214. 2. The minimum mean solar radiation ($cal\;cm^{-2}\;day^{-1}$) of ripening period was not greater than 240 for Jinheung and greater than 270 for IR 667-Suwon 214. 3. The ripened grain ratio was not different from main culm to first tillers of second order of main culm in Jinheung but greatly decreased from 4th tiller of first order of main culm in IR667 and the number of grain per main culm was greater in IR667 than in Jinheung indicating that yield of IR667 could be increased by increasing the number of main culm. 4. The last heading date insuring optimum ripening period appeared to be 25th in August for Jinheung and 30th in August for IR667 in Suweon.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.62-62
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• 2022

Among annual precipitation in Korea (1306.3 mm), 54% of it falls intensively in summer, and only about 12.4% falls in April and May, when the water requirement of wheat is the highest. Korean wheat also could be damaged by soil water excess stress as frozen soil thaws after winter (late Feb-Mar). This study was conducted to evaluate effect of soil water stress on yield and quality of Korean wheat cultivar 'Saegeumgang'. Soil water treatments consisted of 4 treatments; water excess treatment in tilling stage (3.23-3.30), drought treatment in ripening stage (Apr-Jun), irrigation treatment in ripening stage (5.10) and standard condition. There was no significant difference between the treatment conditions for culm length, and the number of spike number was the highest in the order of irrigation in the ripening period (951)> standard cultivation (876)> excess water treatment in the tilling stage (752)> drought treatment in the ripening stage (767/m²). Test weight and Thousand grain weight were 548g/L and 22. lg respectively, which were lower than other treatments, and there was no significant difference between the other treatments. Abortive grain was 5.4kg/10a which was lower than other treatment, and there was no significant difference between the other treatment than other treatments. In drought treatment, protein content was 11.9% which is the highest among all treatments, and SDS-sedimentation value was 27.2ml under drought treatment which was very low compared to other treatments. Therefore, wheat yield and spike number were decreased in excess water condition at tilling stage and drought condition at ripening stage. Furthermore, wheat quality became deteriorate in drought condition at ripening stage.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.2
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• pp.107-113
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• 1973

A pot experiment on paddy rice was carried out to investigate the effect of temperature after heading with application of phosphate, potash and silica on the yield and nutrient uptake. The results obtained are as follows: 1. The Grain yield was greatly affected by temperature during ripening. The yield at $20^{\circ}C$ and at $15^{\circ}C$ decreased to 62.3% and to 37.2% of that at $25^{\circ}C$ respectively. However, the application of phosphate, potash and silica at transplanting increased the grain yield even at low temperature of $15^{\circ}C$. 2. Percentage of ripened grain and weight of 1,000 grains decreased with decreasing temperature but they were increased by the application of phosphate, potash and silica at the low temperature of $15^{\circ}C$. 3. The grain filling rate was fast in the early stage of ripening at high temperature while it was fast in the later stage at low temperature. Low temperature damage was severe in the early stage of ripening. 4. Accumulation of carbohydrate in the grain was small at low temperature of $15^{\circ}C$ and the application of phosphate, potash and silica was effective to increase carbohydrate content in the grain at low temperature. 5. The content of T-N and $P_2O_5$ in straw grown at low temperature were high whereaas those of $K_2O$ and $SiO_2$ were low which were increased by the application of potash and silica. 6. There was a positive correlation between the grain yield and rate of ripening, 1,000 grain weight, contents of $K_2O$ and $SiO_2$, $K_2O/N$ and $SiO_2/N$ ratio, but a negative correlation between grain yield and contents of T-N and $P_2O_5$ in the straw at harvesting stage. 7. Ripening rate and weight of 1,000 grains showed a significant positive correlation with $K_2O$, $SiO_2$, $K_2O/N$ and $SiO_2/N$ ratio in the straw. Further, there was a negative correlation between ripening rate and the contents of T-N and $P_2O_5$ but a positive correlation between weight of 1,000 grains and these elements.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.32-32
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• 2017

To increase rice production, manipulating plant architecture, especially developing new high-yielding cultivars with erect leaves, is crucial in rice breeding programs. Leaf inclination angle determines the light extinction coefficient (k) of the canopy. Erect leaves increase light penetration into the canopy and enable dense plantings with a high leaf area index, thus increasing biomass production and grain yield. Because of erect leaves, the high-yielding indica rice cultivar 'Takanari' has smaller k during ripening than 'Koshihikari', a japonica cultivar with good eating quality. In our previous study, using chromosome segment substitution lines (CSSLs) derived from a cross between 'Takanari' and 'Koshihikari', we detected seven quantitative trait loci (QTLs) for leaf inclination angle on chromosomes 1 (two QTLs), 2, 3, 4, 7, and 12. In this study, we developed a near-isogenic line (NIL-3) carrying a 'Takanari' allele for increased leaf inclination angle on chromosome 3 in the 'Koshihikari' genetic background. We compared k, dry matter production, and grain yield of NIL-3 with those of 'Koshihikari' in the field from 2013 to 2016. NIL-3 had higher inclination angles of the flag, second, and third leaves at full heading and 3 (- 4) weeks after full heading and smaller k of the canopy at the ripening stage. Biomass at full heading and leaf area index at full heading and at harvest did not significantly differ between NIL-3 and 'Koshihikari'. However, biomass at harvest was significantly greater in NIL-3 than in 'Koshihikari' due to a higher net assimilation rate at the ripening stage. The photosynthetic rates of the flag and third leaves did not differ between NIL-3 and Koshihikari at ripening. Grain yield was higher in NIL-3 than 'Koshihikari'. Higher panicle number per square meter in NIL-3 contributed to the higher grain yield of NIL-3. We conclude that the QTL on chromosome 3 increases dry matter and grain production in rice by increasing leaf inclination angle.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.229-234
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• 1982

Environmental factors are known in general to influence much on the development of abscission layer and thereby on shedding of plant parts. The present study was carried out to determine the effect of meterological condition during ripening on the grain shatterability of rice plants at harvest. Different meteorological conditions were obtained by shifting transplanting timing of 40 days old rice seedlings 4 times with a 15 days-interval. Grain shatterability was measured as tensile strength of rice grains: it varied within a range of 214g. to 251g. in a practically non-shattering Japonica variety'Jinheung' and l27.5g. to 204g. in an easy shattering Indica \times Japonica progeny variety'Taeback'. In view of field loss of rice, the variation in tensile strength with time of transplanting and harvest did not matter in Jinheung, but was an important factor in Taeback. In Taeback the tensile strength was significantly correlated positively with mean, maximum and minimum air temperature and relative humidity during a certain period of grain ripening, especially during 30 days period before harvest, but diurnal range of air temperature showed a significant, negative correlation with it. The tensile strength seemed to be more closely related with min. air temperature than max. air temperature, and it was not significantly correlated with radiation amount during any period of pre-harvest. Meteorological effect on grain shatterability may vary with variety, but temperature regime during ripening appears to play major role among the meteorological factors in easy shattering and more thermophilic Indica \times Japonica varieties: lower the temperature, greater the shatterability.

• 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.40 no.5
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• pp.662-669
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• 1995

To clarify the effect of temperature during ripening on grain quality, rice plant which was grown under normal natural conditions untill heading stage was subjected various temperature regimes during grain filling stage. Three varieties, Odaebyeo, Hwaseongbyeo and Dongjinbyeo were used. Grains on primary and secondary-rachis branches were harvested seperately and measured specific gravity, grain size and weight. The optimum daily temperature for grain filling of rice during ripening period was about 22$^{\circ}C$ and grain filling under alternating temperature(26/18$^{\circ}C$, day /night) was better than constant temperature (22 /22$^{\circ}C$) based on 1, 000-grain weight and yield. Grain size based on volume per grain was smallest under the constant temperature of 22 /22$^{\circ}C$. The size of secondary-rachis branches was smaller than primary-rachis branch. The difference in size between primary and secondary-rachis branches was biggest in Hwaseongbyeo, followed by Odaebyeo and Dongjinbyeo. The temperature regimes treated did not influence the grain size difference between branches so much. The 1000-grain weight was lighter under high temperature than low temperature in Odaebyeo, but reversed tendency was observed in Dongjinbyeo of secondary rachis-branches.

• 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.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.227-227
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• 2017

This study was conducted to analyze the reduction of quality and ripening rate of rice due to submergence during ripening stage and identify the physiological cause. Korean japonica type rice cultivars, Nampyeong was used in the experiment. The following 7, 14 day after heading, they were then moved into submergence treatment facility and we conducted the tests under three different submergence conditions - T1(clear water and overhead submergence), T2(Muddy water and exposure of Flag leaf end ), T3(Muddy water and overhead submergence), and the treatment lasted for 4days. The decrease of ripening rate was most severe in T3 treatment at 7days after heading, and the decrease of head rice ratio was most severe in T3 treatment at 14days after heading. Meanwhile the starch synthesis was inhibited, as the supply of assimilation products was inhibited in grain during the submergence treatment. And in stem, sucrose content was increased because the soluble carbohydrates accumulated before heading were decomposed. These changes may be due to the consumption of respiratory substrate in anaerobic conditions and the inhibition of the production of photosynthetic products by light interception. In order to see what kind of reaction occurs at the molecular level, we examined the degree of RNA expression in grain, stem and leaf. First, the expression of rna associated with starch synthesis in grain was decreased in all submergence treatment. and especially Ospul(DBE) was more decreased in 14days after heading treatment than 7days after heading treatment. This difference can explain the result that the decrease of head rice ratio was more severe at 14days after heading. And in stem, the expression of rna associated with the supply of assimilation products was decreased in submergence treatment. Finally in leaf, the expression of rna(ADH, ALDH) associated with anaerobic respiration was increased, while the expression of rna associated with photosynthesis was decreased. These results of physiological analysis can used to develop the cultivation technique and to offer the information for breeding the cultivars with tolerant characteristics to submergence stress during ripening stage in rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.2
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• pp.86-97
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• 2018

The objective of this study was to determine the effects of low temperature on starch accumulation in rice grains. We used four major Japonica-type Korean rice cultivars as materials: Jinbu (JB), Junamjosaeng (JJ), Geumyoung (GY), and Hwawang (HW). Rice plants were moved into two phytotrons the day after heading. Temperatures in the two phytotrons were maintained at $19/29^{\circ}C$ (night/day) as the control, and $13/23^{\circ}C$ as the low temperature condition, both under natural daylight with a relative humidity of 65%. The ripening rates of JB and JJ showed no significant difference between the low temperature and control conditions at 45 days after heading (DAH). In contrast, the ripening rates of GY and HW were 86% and 57% lower than those of JB and JJ under the low temperature condition at 45 DAH, respectively. However, the ripening rates of these four varieties at 61 DAH (when accumulated temperature reached $1,100^{\circ}C$) under the low temperature condition were similar to those at 45 DAH under the control condition (JB, 94%; JJ, 97%; GY, 97%; HW, 88%). The total starch contents showed no significant difference between the control and low temperature conditions. However, the amylose contents in the cultivars were higher under the low temperature than under the control condition. The enzyme activities of starch biosynthesis were about 5-10 days slower in cultivars under the low temperature than under the control. The grain-filling rate showed significant correlations with the enzyme activities of SuSase ($r^2=0.70^{***}$), AGPase ($r^2=0.63^{***}$), UDPase ($r^2=0.36^{***}$), StSase ($r^2=0.51^{***}$), and SBE ($r^2=0.59^{***}$). In conclusion, although StSase activity was increased at $13/23^{\circ}C$ up to 20 DAH, there might not be enough time for SBE to synthesize amylopectin, thus affecting the amylose content of HW, which had the slowest grain filling rate. Notably, the decreased activity of SuSase and SBE and late increase in AGPase activity under the low temperature during the ripening stage are considered to be disadvantageous, as they delay ripening and increase the amylose content.