• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.237-244
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• 1994

To elucidate the physiological characteristics of 2 japonica type and 2 tongil type of rice cultivars, photosynthesis, respiration and diurnal changes of photosynthesis rate had been investigated 6 times at each growing stage. The ratios of photosynthetic part of tongil types were higher than those of japonica types at tillering stage. The highest photosynthetic activity was measured on August 1, before heading in each growing stage, and efficiency of photosynthesis showed its the highest on July 25. Diurnal photosynthetic curve at heading stage reached the peak at 11-12 AM, but after 2 weeks from heading stage, the peak apperred at 1-2 PM. Conversion of respiration into photosynthesis for $CO_2$ fixation started 30~60 minutes later than the standard sunrise time and reconversion for carborhdrate accmulation began 50~60 minutes earlier than the standard sunset time. Photosynthesis showed positive correlation with chlorophyll content and root activity. Harvest index of tongil type cultivars were significantly higher than those of japonica type cultivars.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.1
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• pp.15-26
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• 1994

To understand the relative contribution of varietal and environmental variation on various grain quality components in rice, grain appearance, milling recovery, several physicochemical properties of rice grain and texture or palatability of cooked rice for milled rice materials of seven cultivars(five japonica & two Tongil-type), produced at six locations of the middle and southern plain area of Korea in 1989, were evaluated and analyzed the obtained data. Highly significant varietal variations were detected in all grain quality components of the rice materials and marked locational variations with about 14-54% portion of total variation were recognized in grain appearance, milling recovery, alkali digestibility, protein content, K /Mg ratio, gelatinization temperature, breakdown and setback viscosities. Variations of variety x location interaction were especially large in overall palatability score of cooked rice and consistency or set- back viscosities of amylograph. Tongil-type cultivars showed poor marketing quality, lower milling recovery, slightly lower alkali digestibility and amylose content, a little higher protein content and K /Mg ratio, relatively higher peak, breakdown and consistency viscosities, significantly lower setback viscosity, and more undesirable palatability of cooked rice compared with japonica rices. The japonica rice varieties possessing good palatability of cooked rice were slightly low in protein content and a little high in K /Mg ratio and stickiness /hardness ratio of cooked rice. Rice 1000-kernel weight was significantly heavier in rice materials produced in Iri lowland compared with other locations. Milling recovery from rough to brown rice and ripening quality were lowest in Milyang late-planted rice while highest in Iri lowland and Gyehwa reclaimed-land rice. Amylose content of milled rice was about 1% lower in Gyehwa rice compared with other locations. Protein content of polished rice was about 1% lower in rice materials of middle plain area than those of southern plain regions. K/Mg ratio of milled rice was lowest in Iri rice while highest in Milyang rice. Alkali digestibility was highest in Milyang rice while lowest in Honam plain rice, but the temperature of gelatinization initiation of rice flour in amylograph was lowest in Suwon and Iri rices while highest in Milyang rice. Breakdown viscosity was lowest in Milyang rice and next lower in Ichon lowland rice while highest in Gyehwa and Iri rices, and setback viscosity was the contrary tendency. The stickiness/hardness ratio of cooked rice was slightly lower in southern-plain rices than in middle-plain ones, and the palatability of cooked rice was best in Namyang reclaimed-land rice and next better with the order of Suwon$\geq$Iri$\geq$Ichon$\geq$Gyehwa$\geq$Milyang rices. The rice materials can be classified genotypically into two ecotypes of japonica and Tongil-type rice groups, and environmentally into three regions of Milyang, middle and Honam lowland by the distribution on the plane of 1st and 2nd principal components contracted from eleven grain quality properties closely associated with palatability of cooked rice by principal component analysis.

• Korean journal of food and cookery science
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• v.23 no.4 s.100
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• pp.452-460
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• 2007

As a preliminary study for developing cooking techniques to improve cooked rice flavor, we surveyed consumer perceptions on purchasing rice and the consumption of cooked rice. The quantity of rice purchased by consumers was in the range of $1O{\sim}20$ kg. The purchase criterion for 50% of the subjects was the taste of the cooked rice, and half of the subjects bought their rice at a supermarket. A majority (90%) of the subjects consumed the rice within 1 to 4 months, storing it raw in the package (32.4%) or in a container at room temperature. The rice was cooked for 2 to 5 persons (65%), 1 to 2 times a day (70%) with a pressure cooker (76%). The rice and water volume were measured by eye. The cooked rice was eaten immediately (41.8%) or in 1 to 2 days (48.6%) by keeping it in an electric cooker (63.6%). The subjects perceived the rice cultivar (37.9%) as the major factor for the cooked rice flavor, as well as the region of origin (21.3%), and storage period (11.9%); the cultivars of Ilmi, Ilpoom and Chuchung were preferred. In conclusion, the consumers regard rice as a principal food; however, the methods to measure rice and water are not standardized. To improve the taste of cooked rice, consumers depend on cooking equipment and the rice cultivar.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.513-523
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• 1993

Varietal difference in structural and physical characteristics of rice starch and interrelationships between these starch properties and the physicochemical components of rice grains were investigated for twenty four rice varieties, which were considerably different in amylose content, gelatinization temperature and gel consistency, to obtain the basic informations for diversifying the utility of rice grains and for developing various rice cultivars adaptable to rice food processing. Wave length of maximum absorbance for blue color reaction of starch-I$_2$ complex was 520nm for glutinous rice and 560～600nm for nonglutinous rice. The higher amylose rice showed the longer wave length but there was considerable difference of the wave length among rice materials with similar amylose content. Varietal difference in frequency distribution of debranched starch molecules by isoamylase hydrolysis was largest in amylose fraction, the longest fraction(Fr. I), and was next bigger in intermediate fraction(Int.Fr.) and the ratio between short and long glucose chain of amylopectin fraction(Fr. III /Fr. II). The Fr. III / Fr II ratio was higher in glutinous rice than in nonglutinous one but it was considerably different among nonglutinous rice varieties without any connection with amylose content. The lower alkali digestible rice showed the longer half-hydrolysis time in acid solution. Both soft and hard gel rice varieties in gel consistency test revealed significant varietal difference of 50% acid hydrolysis time. The harder rice in gel consistency exhibited the less frequency of short branch fraction of amylopectin (Fr. III) and the higher amylose content. Twenty four rice varieties were cleary classified by upper two principal components contracted from structural or physical traits of rice starch and some physicochemical properties of rice grain by principal component analysis. The 1st and 2nd principal components can be characterized to components related with amylose and amylopectin structure respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.6
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• pp.521-531
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• 1991

Greenhouse experiments were conducted at the International Rice Research Institute during the 1989 dry season to investigate varietal differences in morpho-anatomical characters affecting spikelet filling in different tiller orders. There were varietal differences in tiller initiation and heading dates, and tiller duration. The main culm bad competitive advantage over the other tillers. The maximum contribution to filled spikelet weight was made by primary tillers in low tillering cultivars and by secondary tillers in high tillering cultivars. The reduction in inner vascular bundle (IVB) by tiller orders and the namber of IVB and outer vascular bundles (OVB) varied amop.g cultivars. The number of IVB in the peduncle of IR30, Rewa and Hybrid was more than OVB but in IR47705, Silewah, Unbongbyeo and SR14453, OVB was more than IVB. Early formed tillers produced more IVB than the late formed tillers. The number of IVB was positively correlated with number of spikelet and filled spikelet weight, however percent of filled spikelet did not show significant differences as well as 1000 spikelet weight in all types of cultivars.

• Research in Plant Disease
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• v.26 no.4
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• pp.250-255
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• 2020

In order to find if a ferulic acid (FA) can be used as a selection index in cereal breeding for resistance to head blight and mycotoxin production, we analyzed FA in the grains of 80 cultivars of barley, rice, and wheat. FA content ranged 1.66-2.77 mg/g in barley (n=20), 0.56-1.53 mg/g in wheat (n=40), and 0.91-2.13 mg/g in rice (n=20). Among these, 7 cultivars each of barley and wheat with different FA content were tested for head blight and mycotoxin production by 2 Fusarium graminearum and 2 F. asiaticum strains. Mean pathogenicity of the wheat cultivars was significantly less than that of barley with higher FA and among wheat cultivars, there was no correlation between FA content and pathogenicity. Mycotoxin production was also lower in the wheat than in the barley as pathogenicity. However, pathogenicity and toxins produced by F. asiaticum were negatively correlated with FA content in barley. These results indicate that FA is not a resistance factor to head blight by F. asiaticum and F. graminearum or its mycotoxin production in barley and wheat.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.1
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• pp.24-33
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• 1987

Competitive ability and response of grain yield in a mixed cropping of two cultivars having different agronomic traits were evaluated at the Yeongnam Crop Experiment Station in 1984 and 1985. Competitive ability was higher in Indica x Japonica cultivar, Milyang 23, and tall statured cultivar, Samgang-byeo, than in Japonica type cultivar, Nacdongbyeo, short statured type cultivar, Taebaegbyeo, respectively. Compared to pure stand, more grain yield was recorded when mixture rates were over 50% in a seed volume for the mixing rate of high yielding cultivar in two cultivars, but low compared to pure cultivation of the cul-tivar having the higher yielding ability in two cultivars.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.2
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• pp.76-82
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• 1981

A water culture experiment was carried out to elucidate the relationship between the nutritional conditions emphasized on $SiO_2$ of rice plant with the growth stages and rice blast incidence. Two rice cultivars, Milyang 23 and Nakdongbyeo were tested under the two Nitrogen levels and $SiO_2$ applications at the different growth stages. The results obtained were as follows. 1. By silicate application, the incidence of rice blast disease was remarkably reduced possibly due to increase of silicate and decrease of nitrogen contents in rice plant. 2. Silicate application at the late growth stage also reduced infected ratio of neck blast. 3. The effect of silicate on reducing the incidence of rice blast disease was clearer in neck blast than in leaf blast.

• Korean journal of applied entomology
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• v.22 no.3 s.56
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• pp.193-197
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• 1983

In 1981 Rice Black-Streaked Dwarf Virus (RBSDV) was severely occurred in Yeongnam area of Korea. The influence of RBSDV to rice plant was studied with two susceptible cultivars, Nagdongbyeo and Cheongcheongbyeo. The stunting rate was determined by the percentage of plant height of infected plants vs. healthy plants. When the rice plants were severely stunted by RBSDV, the yield components and yield were greatly reduced. The stunting of rice plants infected with RBSDV was caused mostly by the shortening of internodes in upper parts of the culm. The relationship between stunting rate of rice plants and yield was shown to have a negative exponential correlation. The regression equations of the relationship are experssed as follows: In Cheongcheongbyeo $Y=46.6lxe^{-0.0624_\chi}$, and in Nagdongbyeo $Y=54.82xe^{-0.067_\chi}$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.309-314
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• 1990

A pot experiment was carried out to find the effects of chemicals and its application time on the sterility and other agronomic characters of rice. Two rice cultivars, Samgangbyeo, a Tongil type, and Chuchungbyeo, a japonica type rice were treated with maleic hydrazide (6000ppm), ethephon (6000ppm) and GA3 (10ppm) at five different growth stages. The application times of chemicals were comprised of two different stages of stem elongation and booting and panicle emerging stage. Grain sterility and panicle length were measured for panicles per pot. Culm length was measured for pot basis. MH induced complete grain sterility in rice, but caused severe plant damage (phytotoxicity) ; restricted spike emergence and drying out of plant leaves, sheath and panicles. Ethephon induced 50-60% grain sterility in rice with the least in plant damage. GA3 was not effective in inducing grain sterility in rice, but it increased culm length. The earlier application of chemicals, the higher sterility was induced. Both MH and ethephon reduced culm length and grain yield. Also observed was the varietal response in the occurrence of to chemicals Samgangbyeo showed the higher response to chemicals than Chuchungbyeo.