• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.43 no.4
• /
• pp.205-208
• /
• 1998

Silica bodies (phytoliths) are becoming of wide use for pedology, archaeology, paleobotany and paleoecology in botany. This study investigated morphological differences of silica bodies in the lamina of wild, indica type, and japonica type rice. Phytoliths in the epidermis of lamina showed noticeable difference among tested plants. Besides, there were also significant differences in the shape and distribution of the silica bodies around stomata and trichomes. Silica bodies in the lamina of the rice plants could be used to classify subspecies of Oryza genus.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.232-232
• /
• 2017

Rice yields are determined by the number of spikes per unit area, the number of rice per grain, the rate of ripening, and the weight of brown rice gravel. Among these yield components, the most important factor that reflects the characteristics of rice is the number of rice per grain and the number of rice per grain. The characteristics of rice panicle are influenced by genetic factors rather than environmental factors and revealed that it had different genetic characteristics in each of Japonica, Indica and Japonica ${\times}$ Indica type. In general, the number of rice per grain is affected by number of secondary rachis branches and generated spikelets number of secondary rachis branches. This study conducted to investigate the characteristics of the grain according to the planting density of two varieties of Jap. ${\times}$ Ind. type. Number of primary rachis branches and number of primary rachis branches of Palbangmi variety were 9.9 ~ 10.6 and 53.4 ~ 58.5, respectively. Number of secondary rachis branches and number of secondary rachis branches were 25.8 ~ 29.6, 85.8 ~ 101.4, Number of tertiary rachis branch and number of tertiary rachis branches were 1.0 ~ 2.4 and 2.0 ~ 6.1, respectively. Number of primary rachis branches and number of primary rachis branches of Semimyeon variety were 8.6 ~ 9.5 and 43.1 ~ 47.8, respectively. Number of secondary rachis branches and number of secondary rachis branches were 21.0 ~ 24.9, 66.2 ~ 77.9, Number of tertiary rachis branch and number of tertiary rachis branches were 1.6 ~ 2.6 and 3.8 ~ 6.3, respectively. The ratio of the spikelets of primary, secondary and tertiary rachis branches of Palbangmi variety were 37.7 ~ 39.4, 58.0 ~ 60.5 and 1.2 ~ 3.1%, respectively, and those of Semimyeon were 40.1 ~ 42.6 55.0 ~ 56.4 and 2.5 ~ 3.4% respectively. Number of primary and secondary rachis branches of Palbangmi variety showed no difference among the planting density. However, generated spikelets number of secondary rachis branches and ripening rate were higher with lower planting density. The number of secondary rachis branches and generated spikelets number of secondary rachis branches per acre decreased as the planting density increased in the Semimyeon variety

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.44 no.2
• /
• pp.106-111
• /
• 1999

To investigate the effects of planting density and nitrogen level on growth and yield potential of newly bred heavy panicle japonica rice with large grain (Iksan 435 and Iksan 438) or many spikelets per panicle(HR14022-21-8-4 and HR14022-21-8-6), four heavy panicle type rices and two many panicle type rices(Dongjinbyeo and Donganbyeo) as the checks were planted under standard planting density (30$\times$15 cm) and dense planting density (15$\times$15 cm) with two nitrogen levels of standard nitrogen level(110 kg h $a^{-1}$) and heavy nitrogen level(165 kg h $a^{-1}$). Effective tiller rate decreased in dense planting or heavy nitrogen, when compared to standard nitrogen and planting, while leaf area index and to dry weight increased in dense planting or heavy nitrogen. Tiller numbers and panicle numbers were more increased by dense planting than heavy nitrogen, whereas spikelet numbers were more increased by heavy nitrogen than dense planting. Ripened grain ratio was slightly lower only in dense planting. 1,000 grain weight in brown rice was not significantly different in dense planting or heavy nitrogen. Milled rice yield was highest in heavy nitrogen with standard planting for heavy panicle type rice, while yield for many panicle type rice was highest in heavy nitrogen with dense planting, suggesting that many panicle type rice possesses higher adapt-ability for dense planting than heavy panicle type rice. Path coefficient analysis revealed that top dry weight, spikelet number and grain weight were the greatest positive contributors to yield, whereas tiller number was negative to yield.d.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.41 no.4
• /
• pp.434-440
• /
• 1996

This experiment were conducted to elucidate the damage by viviparity during grain filling on grain quality and hulling recovery and to understand the varietal differences of viviparity and the effect of extractive from rice hull of hardly viviparous varieties on seed germination and seedling growth. Ten rice cultivars, such as three indica, four japonica and three Tongil-type rices, were used in this study. The brown rice yield was decreased along with increasing the artificial viviparous treatment periods. At six days after treatment, brown rice yield of Daeseongbyeo was reduce 20% as compared with control. The ratio of head rice was 41.3% at six days after viviparous treatment with $25^{\circ}C$ temperature and over 95% relative humidity, while it was 99.5% in control. Varietal differences of viviparity in three rice groups were ranged from 1.1 to 5.2% in indica rices, 9.2 to 79.7% in japonica rices and 2.1 to 63.7% in Tongil-type rices. Methanol extractives from rice hull of IR36, Shinunbongbyeo and Jungwonbyeo inhibited significantly the germination of Deaseongbyeo.

• Korean Journal of Breeding Science
• /
• v.40 no.2
• /
• pp.119-127
• /
• 2008

A total of 41 microsatellite markers were used with 29 genotypes to examine the relationship between SSR polymorphisms and N-use efficiency related traits with a goal to identify the putative QTLs related to these traits. These primers yielded a total of 183 alleles (average 4.46 alleles per primer), and polymorphism information content (PIC) values of the SSRs ranged from 0.119 to 0.805 with mean value of 0.425. Correlation coefficients were obtained among the four N-use efficiency traits in the 34 accessions and significant positive correlations of relative ratios between grain yield and harvest index (r=0.3404) and total dry matter (r=0.7976), while N uptake showed a moderate level of correlation with the ratios of the grain yield and total dry matter, respectively. 36.5% (15/41) SSR markers were monomorphic among the 25 japonica accessions out of the 29 accessions. Association between SSR genotypes and phenotypic performances from the total (29) or japonica (25) accessions was tested based on a single point analysis. Three putative QTL regions were detected for the ratio of grain yield. These include the chromosomal region containing the RM283 locus on chromosome 1 and RM25 on chromosome 8 (all and japonica accessions) and the region with the SSR marker, RM206 on chromosome 11 (the japonica accessions). For the total dry matter ratio, two chromosomal regions were identified as the putative QTL region. One is the region with the SSR marker, RM162 on chromosome 6 (all and japonica accessions) and the other was the one with the SSR marker RM25 on chromosome 8 (the japonica accessions). Among these markers, RM25 showed associations with both traits.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.28 no.2
• /
• pp.173-183
• /
• 1983

To evaluate growing degree days(GDD) as an index of growth duration of rice plants, 30 days old seedlings of 16 japonica and 14 indica/japonica varieties were transplanted six times from May 10 at the 10-day intervals at Gyeongsan in 1982. The number of days from transplanting to heading decreased as transplanting dates delayed in all japonica varietie and 4 indica/japonica varieties but that of 10 indica/japonica varieties decreased up to June 9 or June 19 transplantings and then it levelled off or increased with further delay of transplanting. However, GDD requirement was similar among transplanting dates at appropriate base temperatures; GDD could be better than calendar day system to classify maturity of varieties especially grown in a wide range of climatic conditions. Required GDD from transplanting to heading of all indica/japonica and early japonica varieties showened a smaller coefficient of variation (CV) compared to longer season japonica varieties. Among GDD methods, an accumulation of daily Max + Min temp./2 -$l0^{\circ}C$ showed the smallest CV for the duration from transplanting to heading, but for ripening period GDD calculated with adjusted maximum temperature when it was higher than $30^{\circ}C$ showed the best results. Heading date did not affect required GDD for maturity of japonica varieties, but in indica/japonica varieties GDD decreased as heading date delayed; at late transplantings ripening period of indica/japonica varieties was less extended compared to japonica varietes due to a decrease in grain weight.

• Korean Journal of Agricultural Science
• /
• v.9 no.2
• /
• pp.569-575
• /
• 1982

Mechanical properties of rice plants were tested to determine compressive force, bending force, tensile force and shear force for improvement of harvesting machines and for efficient utilization of rice culm during the proper harvesting period. Rice varieties used in this study were two Japonica varieties with Irri 348 and Jinju, and two $Indica{\times}Japonica$ hybrids with Seogwang and Taebaeg, which were grown in the standard fertilization field of Chungnam Rural Development Office. Also Jinju and Taebaeg were tested to elucidate the shearing characteristics which included shear force-strain relationship, shear force and shear energy according to the position from the ground level, the shearing angle to the rice culm, and the moisture content. 1. Compressive force, bending force, tensile force and shear force were higher In Japonica varieties than $Indica{\times}Japonica$ hybrids. 2. Shear force to overall culm length decreased progressively to upper positions in Jinju variety but a constant shear force was approximately showed between the ground level and the position of 21cm in Taebaeg variety. 3. Shear force and shear energy increased with increase of the cross sectional area, and the rates of increase were high in general up to the cross sectional area of $10mm^2$ and then they became dull very much. 4. Shear force and shear energy decreased with decrease of moisture content of rice culm after cutting up to the moisture content of 60% (w. b.) and then they did not change significantly.

• Korean Journal of Soil Science and Fertilizer
• /
• v.14 no.4
• /
• pp.201-209
• /
• 1982

In 1980, the abnormal low temperature was lasted during the late stage of rice growing season, thus low temperature injury occurred severely. The severity of the injury and nutrition absorption were investigated. The result obtained were summarized as follows: 1. It was considered that the severe low temperature injury of rice was caused by the low temperature and shorts of sunshine in the late growing season of rice, especially, the minimum air temperature which was lasted for a few days below critical reproductive growing temperature in the meiosis stage affected high the injury. 2. The low tmperature injury was lightened in the no nitrogen applied plot, and becoming severe with high nitrogen levels, but the balanced application of NPK lessened the low temperature injury. 3. The low temperature injury was more severe in Indica and Japonica hybrid than in Japonica cultivar, and the injury was shown as sterilizing, degraded spiklets, ill emerging of head and inhibition of nutrition absorption, etc. 4. Under the low temperature condition, $SiO_2$ content of rice plant was significantly reduced according to the increase of nitrogen levels. 5. Under the low temperature condition, the optimum application amount of nitrogen for Milyang 23, was 13, 6 kg/10a, this was approximately 10kg/10a smaller than average in usual year. The highly reduced rice yield was resulted from the cool injury, and the reducing rate of yield was larger in Indica and Japonica hybrid cultivar than in Japonica cultivar.

• The Korea Genome Conference
• /
• 2004.07a
• /
• pp.42.1-42.1
• /
• 2004

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.21 no.1
• /
• pp.35-42
• /
• 1976

In Korea, two types of rice varieties are being cultivated widely, Japonica and Japonica-Indica cross. Generally speaking, the latter shows weak cold tolerance than the former and so brought about many problems in cultural practices. This study was conducted to investigate the effect . of various temperature conditions on rice seedlings growth, especially the contents of chlorophyll and the percentage of nitrogen. And the result obtained indicated the varieties of Japonica-Indica intend to weak cold tolerance than Japonica varieties.