• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.1
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• pp.103-111
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• 1987

Understanding grain filling characteristics represented by grain filling duration and grain filling rate is import-ant in improving higher yielding varieties and developing better cultural methods of rice (Oryza sativa L.). Recently developed 6 Japonica and 6 Japonica/Indica varieties were grown under 3 nitrogen levels at Experimental Farm of Chungbuk National University in 1986. The range of grain filling duration of 12 varieties was 20.9-39.0 days, while grain filling rate ranged from 53.8 to 136.6 mg. panicle$^{-1}$. day$^{-1}$. Although the difference of the average grain filling duration between Japonica varieties and Japonica/Indica was less than 4 days, the average grain filling rate of Japonica/lndica varieties was greater than Japonica more than 30%. Samgangbyeo showed the shortest grain filling duration of 21.0-24.2 days and the greatest grain filling rate of 119.3-143.8 mgㆍpanicle$^{-1}$. day$^{-1}$ under 3 nitrogen levels, while Seomjinbyeo and Milyang 23 showed the quite opposite grain filling characteristics. Nitrogen levels did not show any significant effects on grain filling characteristics. Negative correlation was round between grain filling duration and grain filling rate, and significant positive correlations of grain filling rate with grains/panicle, grain weight and panicle weight indicated that grain filling rate is more important characteristics of grain filling. Pathway analysis revealed that contribution of grain filling rate to panicle weight is rather indirect through grain weight.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.1
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• pp.112-121
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• 2007

Grain filling is a crucial factor that determines grain yield in crops since it is the final process directly associated with crops' yield performance. Grain filling process can be characterized by the interaction of rate and duration of grain filling. This study was conducted, using 16 temperate japonica rice genotypes, with aims to (1) seek variations in grain filling duration and rate on area basis, (2) compare the contribution of grain filling duration and rate to grain yield, and (3) examine the influence of temperature and solar radiation for effective grain filling on grain yield in relation to grain filling duration and rate. Grain filling rate and duration exhibited highly significant variations in the ranges of $20.7{\sim}46.3\;g\;m^{-2}d^{-1}\;and\;11.2{\sim}35.5$ days, respectively, depending on rice genotypes. Grain yield on unit area basis was associated positively with grain filling duration but negatively with grain filling rate. Grain filling rate and duration were negatively correlated with each other. Final grain weight increased linearly with the rise in both cumulative mean temperature and cumulative solar radiation for effective grain filling. Higher cumulative mean temperature and cumulative solar radiation for effective grain filling were the results of longer grain filling duration, but not necessarily higher daily mean temperature and daily solar radiation for effective grain filling. Grain filling rate demonstrated an increasing tendency with the rise in daily mean temperature for effective grain filling but their relationship was not obviously clear. It was concluded that grain filling duration, which influenced cumulative mean temperature and cumulative solar radiation for effective grain filling, was the main factor that determined grain yield on unit area basis in temperate Japonica rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.2
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• pp.166-173
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• 1991

In order to determine the relationships between the rates of leaf senescence and photosynthate translocation during the grain filling periods in barley, field experiments were conducted through 1989/1990 crop year. Thirty barley varieties and lines having different leaf senescence were used for the experiments. Varieties differed significantly in the rate of leaf senescence and rate of grain filling. The rate of leaf senescence at early (10-20days after heading) and late period (20-30days after heading) during of grain filling were positively correlated with the rate of grain filling in same period, respectively. But the rate of leaf senescence at 10-20 days after heading negatively correlated with the rate of grain filling during the whole grain filling period (10-35 days after heading). Whereas, the rate of leaf senescence at late period was positively associated with the rate of grain filling during the whole grain filling period. Rates of grain filling at the late and whole periods have positively influence on grain weight(r=0.62**～-0.93**), but rate of leaf senescence at early period and duration of grain filling negatively correlated with the grain weight (r=-0.33～ -0.15). The patterns of leaf senescence index for the varieties tested were grouped by four. Among these patterns, the most ideal pattern was IV type.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.5
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• pp.397-401
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• 2003

This experiment was conducted to know the characteristics of kernel growth as affected by various temperature regimes during grain filling using the varieties Hwaseongbyeo, Ilpumbyeo and Chucheongbyeo. The rice plants tested were grown in the natural condition at 1/5000a Wagner pots until flowering. After flowering, the rice plants were moved to controlled temperature conditions in a phytotron. The minimum/maximum daily temperature in the phytotron was controlled by 12/18, 15/21, 18/24, 21/27, and 24/$30^{\circ}C$, respectively. The grain weights were measured every three days after treatment. The mean daily kernel growth rate during active grain filling period showed different responses among varieties under various temperature regimes. The kernel growth rate of Chucheongbyeo was seriously reduced as temperature regimes were decreased. However, that of Ilpumbyeo was not influenced so critically. Ilpumbyeo showed some advantages in grain filling under low temperature regimes compared to Chucheongbyeo. The lag phase in grain filling of Chucheongbyeo was the longest among tested varieties, followed by Hwaseongbyeo under daily mean temperature regime of $15^{\circ}C$. Kernel weight of Ilpumbyeo increased fast in early grain filling phase under low temperature. This characteristic may be favorable for grain filling in temperate zone where the daily mean temperature is drastically dropped during grain filling period. Regression analysis with kernel growth rate and temperature showed the estimated critical low temperature for grain filling among varieties were $9^{\circ}C$, $12^{\circ}C$, $13^{\circ}C$ in Ilpumbyeo, Hwaseongbyeo and Chucheongbyeo, respectively. Under moderate temperature the duration of grain filling of Ilpumbyeo was longer than that of Chucheongbyeo. However, Under low temperature that of Ilpumbyeo was more favorable than Chucheongbyeo.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.1
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• pp.5-11
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• 1988

Varietal differences of grain filling duration and rate are generally recognized in rice (Oryza sativa L.). But the differences of grain filling characteristics between the parts within a panicle might be present since it takes 6-8 days to finish anthesis in a panicle. To elucidate this, 6 Japonica and 6 Japonica/Indica varieties were grown under three nitrogen levels at the Experimental Farm of Chungbuk National University in 1986, and grain filling characteristics of top, middle and bottom parts of a panicle were analyzed. Rice grain filling duration could be divided into 3 phases, i.e., Lag phase(LP) of 5 days after heading. Linear increasing period (LIP) of 5-20 days after heading and Late filling period (LFP) thereafter. Grain weight difference between the panicle parts was greater during LIP in all the varieties and was decreased during LFP. The difference was greater in Japonica/Indica varieties. Samgangbyeo and Seomjinbyeo had the shortest and the longest grain filling durations with 22.6 and 37.1 days, respectively. In average, grain filling duration of the bottom part of a panicle was 1-2 days shorter than that of top or middle part. The differences were negligible in Daecheongbyeo, Taebaegbyeo and Milyang 23, while it was greater in Tongil with 4.9 days. Grain filling rates were ranged from 0.612 to 1.097 mgㆍgrain$^{-1}$ㆍday$^{-1}$ㆍMilyang 23 showed the lowest rate with 0.612-0.682 mgㆍgrain$^{-1}$ㆍday$^{-1}$, while the rates of Baegyangbyeo, Yongmoonbyeo, Samgangbyeo, Nongbaeg and Daeseongbyeo were about 1 mgㆍgrain$^{-1}$ㆍday$^{-1}$ㆍGrain filling rate of bottom part of a panicle was lower than that of top or middle part. The difference was samll in Nongbaeg and Daeseongbyeo, while it was the greatest in Tongil with 0.222 mgㆍgrain$^{-1}$ㆍday$^{-1}$. Grain filling duration and rate were not afftected by nitrogen level, but varietal and spatial differences of grain filling characteristics were highly significant. However, the spatial difference of grain filling rates within a variety was not significant. Grain filling characteristics of each part of a panicle were significantly correlated (r=0.7207-0.9879) with those of a whole panicle.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.1
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• pp.44-49
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• 2003

In vitro culture of panicle has been the method to accumulate starch and protein in immature grains by providing nutrients after florets crossed between remote genotypes artificially. Grain filling means embryo development and sucrose translocation from photosynthetic source, and starch manufacture in endosperm. The concentrations of sucrose used to culture immature rice panicle were 5, 10, 15, 20% and glutamine was 20 mM. When immature rice panicles at 5 days after flowering were cultured in distilled water with different concentrations of sucrose, glutamine 20 mM and MS medium with different concentrations of sucrose, glutamine 20 mM for 30 days the later was effective on grain filling. The optimal concentration of sucrose on grain filling in vitro culture of rice panicle was 10% and the weight of grain cultured was 10.14 mg that was corresponded to 57% of intact plant. In the method of treating plant growth regulators, the culture of immature rice panicle adding in MS medium with Kinetin, IAA, $\textrm{GA}_3$ were effective on grain filling than the culturing of immature rice panicle after submerging in solutions of Kinetin, IAA, $\textrm{GA}_3$ for 1day. When immature rice panicle was cultured in MS medium with sucrose 10% and Kinetin 46.47 $\mu$M it was effective on grain filling, respectively. The weight of grain cultured was 13.1mg that was corresponded to 75% of intact and germination rate was 51 %. When immature rice panicles were cultured in medium with different concentrations combined with Kinetin 4.65, 46.47, 464.7 $\mu\textrm{M}$, IAA 5.71, 57.08, 570.80 $\mu\textrm{M}$ for 30 days and in medium with IAA 5.71, 57.08, 570.80 $\mu\textrm{M}$ for 15 days after culturing in medium with Kinetin 4.65, 46.47, 464.70 $\mu\textrm{M}$ for 15 days the effect on grain filling was similar.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.59-59
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• 2017

Rice (Oryza sativa L.) is the most important crop and its yield must be improved to feed the increasing global population. Recently developed high-yielding varieties with extra-large sink capacity often have a problem in unstable grain-filling. Therefore, understanding limiting factors for improving grain-filling and controlling them are essential for further improvement of rice grain yield. However, since grain-filling rate was determined by complex sink-source balance, the ability of grain-filling was very difficult to evaluate. Source ability for 'grain' was not only determined by the ability of carbon assimilation in leaves, but also that of carbon translocation from leaves to panicles. Sink strength was determined by the complex carbon metabolism from sucrose degradation to starch synthesis. Hence, to evaluate the grain-filling ability and determine its regulatory steps, the whole picture of carbon flow from photosynthesis at leaves to starch synthesis at grains must be revealed in a metabolite level. In this study, the yield and grain growth rate of three high-yielding varieties, which show high sink capacity commonly, were compared. Momiroman showed lower grain filling rate and slower grain growth rate than the other varieties, Hokuriku 193 and Tequing. To clarify the limiting point in the carbon flow of Momiroman, $CO_2$ labeled by stable isotope ($^{13}C$) was fed to three varieties during ripening period. The ratio of $^{13}C$ left in the stem was higher in Momiroman 24 hours after feeding, suggesting inefficient carbon translocation of Momiroman. More interestingly, $^{13}C$ translocation from soluble fraction to insoluble one in the grain seemed to be slower in Momiroman. To get the further insight in a metabolite level, we are now trying the $^{13}C$ labeling metabolome analysis in the developing grains.

• 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.33 no.3
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• pp.262-269
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• 1988

Experiments were conducted to find out the method of reducing viviparous germination of rice seeds using growth regulators during grain filling period. Among the recommended varieties, early Japonica type showed higher rate of viviparous germination, while late Japonica type and Tongil type varieties did not show viviparous germination in field condition. Grain showed high germination ability from 30 days of grain filling period in Daeseongbyeo of Japonica type and 35 days in Taebackbyeo of Tongil type. Growth regulators, NAA, CMH and Reglone were effective for reducing viviparous germination to the two rice varieties and three treatment stages in this experiment. NAA and CMH were most effective at 100 ppm and Reglone was at 0.4-0.6% concentration. Germination rates of rice seed were not different from non-treatment when NAA CMH were treated, while Reglone lowered germination rate. NAA and CMH had no effects on grain filling rate for both varieties, which showed high grain filling rate as the non-treatment, but Reglone results low grain filling rate. Grain color was not changes when NAA was applied, while CMH and Reglone made a lot of grain to dark brown as the concentration became higher. When grain were hulled, NAA had no difference with the non-treatment whereas CMH and Reglone had lower rate of perfect brown rice when they were applied at 20-30 days after heading.

• 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.