• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.1
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• pp.135-143
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• 2018

The effect of elevated temperature on temperate paddy rice will be significant for dependable food supply in East Asia. Using temperature gradient field chamber (TGFC), which was designed to make the horizontal air temperature gradient by $0^{\circ}C$ to $3^{\circ}C$ higher than outside, we examined the measurement to understand the effects of extremely high temperature on paddy rice. In particular, the data of the year 2016, the worst heat wave in over 22 years, was analyzed in this study. The rice height in the relatively warmed condition was rapidly increased during early growth stage. However, the average grain weight and number of spikelet per panicle in the warmed chamber condition were gradually declined with increasing air temperature averaged for 40 days after first heading in each chamber. In particular, the grain yield was more dramatically decreased by the raising temperature because the percent ripened grain was quickly dropped as getting over the threshold temperature for pollination. Therefore, the surplus photosynthetic product by such lower grain filling rate may disturbed the decreases of the NDVI (Normalized Difference Vegetation Index) and SPAD chlorophyll values after first (normal) heading. In addition, the late-emerging head grain were appeared. However, this yield was too small to recover the normal yields decreased by extremely high temperature condition. Our result represented that the warmed condition in 2016 would be the critical limit for the stable yield of temperate paddy rice.

• Korean Journal of Plant Resources
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• v.36 no.3
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• pp.225-236
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• 2023

Stomatal traits such as stomata density (SD), aperture length (APL) and width (APW), guard cell length (GCL) and width (GCW), and distance between stomata (DIS) were investigated to identify correlation with agronomic traits for 35 Korean wheat cultivars. Flag leaf width (FLW) of Korean wheat cultivars was the widest in Ol-mil, and the narrowest in Keumkang. SD tended to be higher on the adaxial side than on the abaxial side in Korean wheat cultivars. SD of adaxial and abaxial sides was classified into a cultivar with a significantly different or not. In APL, 18 wheat cultivars showed significant differences according to leaf side, and APL of adaxial was longer than APL of abaxial in 13 wheat cultivars. In APW, 15 wheat cultivars showed a significant difference, and APW of abaxial was wider than APW of adaxial among them. In GCL, 14 wheat cultivars showed a significant difference, and the GCL of abaxial was longer than the GCL of adaxial in 10 wheat cultivars. In GCW, 10 wheat cultivars showed a significant difference, GCW of adaxial was wider than GCW of abaxial and in 6 wheat cultivars. FLW of adaxial and abaxial showed a negative correlation with GCL and a positive correlation with grain number per panicle. FLW of only abaxial showed a positive correlation with DIS. The SD of the adaxial showed a negative correlation with GCL, while the SD of the abaxial showed a negative correlation with APL. APL of both sides of the leaf showed a positive correlation with GCL, and APW of only abaxial showed a negative correlation with GLC. DIS of adaxial showed a negative correlation with tiller number (TN), while DIS of abaxial showed a positive correlation with GNP.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.522-527
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• 1997

To find out the optimum seeding rate in corrugated water seeded rice, field experiment was carried out at Yeongdeog Substation of the National Yeongnam Agricultural Experiment Station for two years, 1994 and 1995. A rice cultivar Donghaebyeo, was seeded on May 15 with five seeding rate from 3kg /10a to 7kg /10a. The number of seedling stand per unit area was curvilinearly increased with seeding rate. In characteristics of rice plant associated with lodging, the plant height, fresh weight per tiller, Culm wall thickness and ratio of gravity center were not significantly different among seeding rates, but the breaking strength of 4th internode was slightly decreased with increasing seeding rate and thus, lodging index was generally greater at higher seeding rate than lower seeding rate. Field lodging was observed at 1~3 degree in seeding rate of 5~7kg /10a. Panicle number per unit area was generally increase with increase of seeding rate, while ratio of ripened grain was decreased with increase of spikelet number. Milled rice yield was curvilinearly increased with seeding rate. The optimum seeding rate in the highest rice yield was 4.8kg /10a in 1994, and 4.3kg /a in 1995, respectively.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.232-237
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• 2001

This study was conducted to clarify the effects of physical stimulation to the rice plant by free-ranging ducks (Chinese native ducks) on growth, lodging resistance and yield of the rice plants in a rice-duck farming system. Two paddy fields were used for this experiment, one exposed to physical stimulation (PS) and the other with no physical stimulation (NPS). Fifteen days after ducks were introduced into the paddy plot, rice plants in the PS field were significantly (P<0.05) shorter than those in the NPS field. Measurements of lodging characteristics showed that, the 3rd internode was significantly (P<0.05) shorter in the PS treatment than in the NPS treatment, but neither the 4th internode length nor the center of gravity of the rice plants differed between treatments. The breaking strength of $N_4$ in PS rice was significantly (P<0.05) higher than in NPS rice, however the bending moment and the lodging index of $N_3$ (distance between fulcra - 5 cm) was significantly (P<0.05) lower in PS than in NPS. The number of panicles per $m^2$ was significantly (P<0.05) greater in PS rice than in NPS, but there was no such difference in spikelet number per panicle, percentage of ripened grain or weight per 1000 kernels. Paddy rice yield per $m^2$ in the PS treatment was significantly (P<0.05) higher than that in the NPS treatment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.2
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• pp.198-208
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• 1992

Recently, a nursery mat made from rock wool has realized transplanting of the younger seedlings with the ordinary transplanting machines for Chibyo and Chubyo(3 and 4～5 leaved seedling, respectively). The seedlings defined as the 'Nyubyo' or 'Nursling seedlings' became possible to achieve economic profits from the reduction in both working time and costs. It being widely noticed as a strategy to solve the difficulties in current rice cultivation. The nursling seedlings are 1.4 to 2.5 leaves and height at 4.5 to 7cm, grown 4 to 7 days after seeding. They maintain still up to 50 to 80% of their nutrients in the endosperm, and can grow by using only their own nutrients for a certain period of time after transplanting. Nursling seedlings take 2 days in the nursery chamber at 32$^{\circ}C$ after seeding, and 2 days in the greening house at $25^{\circ}C$. This is only 4 days, all together, to make the nursling seedlings of 1.5 leaves which are ready for transplanting. Watering is only needed once at the sowing time. It only takes 1 or 2 waterings even to raise a seedlings for a period of 7 days. The number of nursery boxes can be reduced because it is possible to sow more densely(220 to 240g per box), thus it only needs seedlings of 15 to 16 boxes per 10 a which leads to a reduction in facilities and space needed. Temperature during the nursery period can be artificially adjusted more precisely which may lead to the prevention of temperature stress. The nursling seedlings can root rapid by because the crown roots from the coleoptile node begin to emerge immediately after transplanting. They show strong resistance to low temperature (12$^{\circ}C$) and deep-planting. There is no danger in the rooting of the seedlings even if half of their height is buried into the soil. Moreover, it can root at a rate of up to 65 to 80% even if the full height of the seedlings is buried. They show also strong resistance to submergence (10～15cm). The nursling seedlings tend to grow by producing tillers from lower nodes. It is therefore, necessary to control to keep the proper numbers of tillers per unit area. They have no fear in the delay of heading and their yield components can be so well balanced that the same level of yield was achieved with the nursling seedlings compared to that with Chibyo. It was further suggested that if the surplus tillers can be avoided by such cultivation practices, the number of grain per panicle can be kept greater and higher yield can be realized. Practical experiments with the nursling seedlings conducted in 1989 and 1990 by farmers in various areas showed exciting results. The nursling seedlings will become widely spread, or at least occupy an important position in Japanese and also in Korean rice cultivation techniques.tivation techniques.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.5
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• pp.418-424
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• 1993

In order to test combining ability of the cytoplasmic-genetic male sterile(CGMS) and restorer lines with backgrounds of Korean japonica rice varieties, diallel crosses were made among the early maturing CGMS lines Sobaegbyeo A, Odaebyeo A, Gwanagbyeo A and Daeseongbyeo A, and the restorer lines Sobaegbyeo R, Odaebyeo R, Gwanagbyeo Rand Daeseongbyeo R, and among the medium maturing CGMS lines Hwajinbyeo A, Paldal A, Suwon 224 A and Iri 386 A and the restorer lines Hwajinbyeo R, Paldal R, Suwon 224 Rand Iri 386 R, and among the late maturing CGMS lines Nagdongbyeo A, Palkweng A, Hwacheongbyeo A and Milyang 97 A and the restorer lines Nagdongbyeo R, Palkweng R, H wacheongbyeo Rand Milyang 97 R. The fourty eight combinations of the hybrids, their parents and the maintainers were grown in field condition in 1992. General combining ability, relative specific combining ability and relative combining ability for yield of the CGMS and restorer lines were tested. Combining ability of the CGMS lines Odaebyeo A, Iri 386 A, Nagdongbyeo A and Palkweng A, and of the restorer lines Odaebyeo R, Hwajinbyeo R, Hwacheongbyeo Rand Palkweng R was relatively high. Heterobeltiosis for grain yield over the better parent of the early maturing hybrids ranged from -17 % to 15%, and that of the medium maturing ones from -4% to 22%, and that of the late maturing ones from -46% to 30% respectively, Standard heterosis over the standard variety of the early maturing hybrids ranged from -13 % to 12 %, and that of the medium maturing ones from 0 % to 26%, and that of the late maturing ones from -38% to 26% respectively, Positive and negative heterosis for grain yield of the hybrid rices were observed depending on cross combinations, In the positive heterosis hybrids, number of panicles per hill and number of spikelets per panicle contributed mostly to grain yield, while in the negative heterosis hybrids, spikelet fertility and 1000 grain weight were closely correlated to grain yield. Amylose content of the hybrid rices, maintainer and restorer lines was mostly lower than 20 %, and alkali digestion value was higher than 6.0. Grain appearance of the hybrids tested was similar to the korean japonica rice varieties.

• Korean Journal of Weed Science
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• v.31 no.2
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• pp.134-145
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• 2011

The objectives of this study were to investigate fitness difference in growth and rice yield in herbicide-transgenic rice overexpressing Myxococcus xanthus and Arabidopsis thaliana protoporphyrinogen oxidase (Protox) genes and non-transgenic rice. We also aimed to determine whether these fitness differences are related to ALA synthesizing capacity, accumulation of terapyrroles, reactive oxygen species, lipid peroxidation, and antioxidative enzymes at different growth stages of rice. Plant height of the transgenic rice overexpressing M. xanthus (MX) and A. thaliana (AP37) Protox genes at 43, 50, and 65 days after transplanting (DAT) was significantly lower than that of WT. Number of tiller of PX as well as MX and AP37 at 50 and 65 DAT was significantly lower than that of WT. At harvest time, culm length and yield of MX, PX and AP37 and rice straw weight of MX and AP37 were significantly low compared with WT. The reduction of yield in MX, PX, and AP37 was caused by spikelets per panicle and 1000 grain weight, ripened grain, spikelets per panicle, 1000 grain weight, and ripened grain, respectively. On the other hand, 135 the reduction of yield in MX, PX, and AP37 was also observed in another yearly variation experiment. The reduction of rice growth in MX, PX, and AP37 was observed in seedling stage as well as growth duration in field. There were no differences in tetrapyrrole intermediate Proto IX, Mg-Proto IX and Mg-Proto IX monomethyl ester, reactive oxygen species ($H_2O_2$ and ${O_2}^-$), MDA, antioxidative enzymes (SOD, CAT, POX, APX, and GR) and chlorophyll between transgenic lines and wild type, indicating that accumulated tetrapyrrole intermediate and other parameters were not related to growth reduction in transgenic rice. However, ALA synthesizing capacity in MX, PX, and AP37 at one day after exposure to light and 52 DAT was significantly lower than that of WT. Further study is required to elucidate the mechanisms underlying the growth and yield difference between transgenic and WT lines.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.2
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• pp.87-91
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• 2016

Recently, rice growth and production have been influenced by climatic change worldwide. In particular, under low solar radiation and cloudy weather, rice plants show abnormal physiological responses. In this experiment, plants of the rice cultivar Samgwangbyeo grown 40% and 70% shading and natural conditions at the primordium initiation stage (PI) for 30 days and the booting stage for 10 days up to heading were compared. After shading treatments, culm lengths were significnatly longer than that in natural condition plots, and panicle lengths were shorter in the 40% and 70% shading treatment plots compared to control plots. After heading, the production of dry matter treated at the PI stage was significantly lower than that at the booting stage. SPAD values of the leaf color and N concentration of leaves treated with shading were greater than those under natural conditions. In the shading treatment, the lodging index at 20 days after heading was significantly higher than that in natural condition. For yield components, number of panicles, spikelet number per panicle, and ripened grain ratio significantly decreased with shading treatment; thus, rice yield decreased significantly. For rice quality, the protein content of the head rice treated with shading was significantly higher than that in the control plot, but the amylose content of rice treated with shading was signifiantly lower than that in rice in control plots.

• Korean Journal of Breeding Science
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• v.42 no.4
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• pp.407-412
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• 2010

Recently, peoples are greatly concerned with global temperature change because global warming can be a potential serious effect on agriculture production such as yield reduction and poor grain quality. On the other hand, it can bring some beneficial effects through twice cultivation of rice in temperate region. In order to overcome this situation, we developed extremely early-maturing rice 'Milyang255' which heading date was similar with 'Jinbuolbyeo'. Based on agronomic characteristics of 'Milyang255', it has very short stature as 65 cm of culm length and slightly lower spikelets number per panicle compared with that of 'Jinbuolbyeo'. However, the grain appearance, palatability and other items were better than those of 'Jinbuolbyeo' in panel test of cooked rice. The milled rice yield of 'Milyang255' is 3.94 MT/ha at the early transplanting. Especially, its grain filling rate was higher and faster than Jinbuolbyeo and the head rice ratio in milled rice was also higher. Thus, 'Milyang255' can efficiently reduce the growth duration of rice cultivation and also be useful material for research on twice cultivation of rice in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.352-361
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• 1990

The reducing effect of wind injury was investigated using several wind-break nets in Youngdeok province where cold-wind damage is often occurred during rice growing season. The white-head damage of rice have been often occurred by typhoon during the period between August 15 to September 10 in the cold wind area of the eastern coastal during the last 11 years (1979-1989). This may suggest that the critical period for heading will be by August 15 in the regions. High evaporation coefficient, more than 250 due to typhoon passage over the regions resulted high injury of white head. Generally, the wind injury have been caused by warm and dry westerlies through Fohn apperance in Taebaeg mountains and by cool-humid wind which blows from coast to inland. The frequency of occurrence of the two types of typhoons were 25, 20%, respectively during rice cultivation. The instalation of wind-break net significantly reduced the wind blowing speed, depending on the net mesher with the higher effect in dence net. The distances between the net and cropping area also affect the wind speed: 23% reduction at 1m distance. 34% at 10m and 28% at 20m, respectively. The reducing effect was also observed even at 10 times height of the wind-break net. The instalation of wind-break net gave several effects on climate factor, showing that temperature increased by 0.8$^{\circ}C$(maximum), 0.7$^{\circ}C$(minimum), 0.6$^{\circ}C$(average) : water temperatures increased by 0.5$^{\circ}C$(maximum), 0.6$^{\circ}C$(minimum), 0.5$^{\circ}C$(average) : soil temperature increased 0.4$^{\circ}C$. The earlier heading and increasing growth rate, use of light, culm length, panicle number per hill, spikelet number per panicle, fertility and 1,000 grain weight were observed in the fields with the wind-break nets resulting in 10-15% increase in rice yield using 0.5${\times}$0.5cm nets. The increasing seedlings per hill gave higher grain yield by 13% in the cold wind damage regions of eastern coastals. and the wind-break was more significant in the field without the wind-break net. Wind injury of rice plant in the cold wind regions of eastern coastals in korea could be reduced by selection of tolerant varieties to wind injury, adjustment of transplanting time, and establishment of wind-break nets.