• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.59 no.1
• /
• pp.22-26
• /
• 2014

This research was implemented to investigate pre-harvest sprouting characteristics in two Korean rice cultivars, Shindongjin (SDJ) and Hopum (HP). The panicles of both varieties were sampled after 15 days after heading (DAH) to 60 DAH at intervals of 5 days. As soon as sampled, the panicles were imbibed in water for 14 days at $25^{\circ}C$ to determine the vigor and germination ability of seeds according to location on panicle. To investigate the cause of non-germination of seeds in panicles, tetrazolium test and dormancy breaking were performed. The preharvest sprouting of HP started at 20 DAH while that of SDJ began at 30 DAH. The germination of seeds located in high rank branches within a panicle and the terminal seeds within a branch were earlier and faster and the germination patterns were same in both cultivars. The times at more than 50% of germination in a panicle were 35 DAH (57.0%) in HP and 45 DAH (56.8%) in SDJ. Preharvest sprouting was more than 80% at 50 DAH (82.6% of HP, 92.3% of SDJ) and more than 99% at 60 DAH (99.5%, 99.4%, HP and SDJ). These results indicated that the rate of PHS in a panicle increased with accumulation of the days after heading. The cause of non-germinated seeds at 15-25 DAH in panicle was immature embryo. After 30 DAH, however, when the non-germinated seeds were hulled, they started to germinate due to dormancy breaking, in which the germination percentage was higher in SDJ than HP. In conclusion, the pre-harvest sprouting varied according to days after heading, the seed position on panicle, and the dormancy intensity of varieties.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.59 no.1
• /
• pp.73-82
• /
• 2014

This study was conducted to investigate the ear and kernel characteristics of waxy corn during ripening by double cropping, and to understand the pattern of starch accumulation in endosperm of waxy corn kernels. Chalok4 and Ilmichal were sown at April 20 (first cropping) and July 20 (second cropping) in 2011~2012. The accumulated temperature from silking to harvesting was about $590{\sim}630^{\circ}C$. It takes 23~24 days when Chalok4 and Ilmichal were sown in April 20, but July 20 sowing takes 32~35 days. Ear length and kernel set length were significantly shorter in second cropping (p<0.05). Kernel length, kernel width, 100-kernel weight, and starch content of waxy corn were increased as ears matured (p<0.05). Growth temperature was getting decreased during the ripening stage of second cropping, the rate of ear and kernel development had slowed. Starch granules started to accumulate in the cells around the pericarp, then developed in the cells around the embryo. In the second cropping, starch granules in the kernel of waxy corn were less compact than the first cropping, harvesting time of waxy corns can be extended. These results will be helpful to farmers for double cropping of waxy corn cultivation and management.

• Korean Journal of Remote Sensing
• /
• v.33 no.5_2
• /
• pp.733-740
• /
• 2017

This review introduces the empirical approach of rice yield forecasting and compares it with remote sensing approach. The empirical approach, was based on the results of the rice growth and yield monitoring experiment in 17 sites, estimated rice yield by recombination of yield components. The number of spikelet per unit area was from results of experiment sites and grain filling rate was estimated from linear regression with sunshine hours. The estimation results were relatively accurate from 2010 to 2016. The smallest error was 1 kg / 10a and the largest error was 19 kg / 10a. The largest error was caused by the typhoon. The empirical approach did not fully reflect the spatial variation caused by disasters such as typhoon or pest. On the other hand, remote sensing could explain spatial variation caused by disasters. Therefore, if there are not any disaster in rice field, both approaches are valid and remote sensing will be more accurate when any local disaster occurs.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.59 no.4
• /
• pp.445-456
• /
• 2014

This study was conducted to investigate the kernel characteristics of sweet corn during ripening with different sowing date. Godangok and Guseulok were sown at April 10, July 10, July 20, and July 30 in 2013. Irrespective of sowing date, fresh and dry weight of 100 kernel, starch content, crude fat content, and hardness of sweet corn kernels were significantly increased according to maturation (p<0.05). But moisture content, total sugar content, crude protein content and crude ash content of sweet corn kernels were significantly decreased according to maturation (p<0.05). The changing rates of 100 kernel weight and starch content on kernels were faster at early sowing date than at late sowing date. The moisture content of sweet corn kernels was 68~69% at optimum for harvesting. The degree of sweetness on Godangok was about 1.8 and 1.4 times higher in sowing at July 20 and July 30 than in sowing at April 10. On the other hand, the degree of sweetness was similar regardless of sowing time on Guseulok. These results will be helpful to farmers for fall-harvest sweet corn cultivation and management.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.52 no.1
• /
• pp.1-11
• /
• 2007

Light is an environmental component inevitably regulating photosynthesis and photo-morphogenesis, which are involved in the plant growth and development. Studies were conducted at the International Rice Research Institute, Philippines in 2004 and 2005, with aims to investigate 1) morphological responses of rice plants to low radiation, 2) morphological alteration of shade-grown plants when exposed to high light intensity, and 3) photosynthetic responses of shade-grown rice plants. Reduction in solar radiation by 40% induced increases in the area on a single leaf basis, biomass partitioning to leaves, and chlorophyll meter readings but brought about retardation of tiller development and decrease in above-ground biomass production of rice varieties. When the shade-grown plants from two weeks of transplanting to panicle initiation were exposed to full solar radiation after panicle initiation, they demonstrated less increase in chlorophyll meter readings and more decrease in leaf nitrogen concentrations from panicle initiation to flowering than control plants that were grown under the ambient solar radiation for whole growth period after transplanting. Shade-grown rice plants exhibited lower carbon assimilation rates but higher internal $CO_2$ concentrations on a single leaf basis than control plants, when measurements for shade-grown rice plants were made under the shading treatments. But when the measurements for shade-grown plants were made under the full solar radiation, light-saturated carbon assimilation rates were similar to control plants. Response of photosynthetic rates to varying light intensities was not considerably different between shading treatments and control. Yield reduction was observed in the shading treatments from panicle initiation to flowering and from flowering to physiological maturity, mainly by less spikelets per panicle and poor grain filling, respectively.

• Korean Journal of Environmental Agriculture
• /
• v.18 no.1
• /
• pp.11-17
• /
• 1999

This experiment was conducted to select and utilize the tolerant rice varieties for ozone stress through comparing the physiological responses. In SOD activity, Backunchalbyeo which treated once by 0.15 ppm $0_3$, Ilpumbyeo and Inbujinado treated twice showed significantly different SOD activity compared with $non-O_3$ treatment. No significant difference of SOD activity in three-times $0_3$ treated Sangnambatbyeo and Hangangchalbyeo was found as compared to ($non-O_3$ treated)control, POD activity, when Sangnammbatbyeo, Hangsngchalbyeo, Ilpumbyeo and Inbujinado were sequently treated by third ozone, showed no significant difference between $O_3$ treatment and $non-O_3$. In the comparison of amino acid content in rice leaf blade between three times $O_3$ treatment and $non-0_3$ treatment in 3 varieties, phenylalanine content represent as increased quantities. Especially, in three times $0_3$ treatment of Sangnambatbyeo, phenylalanine content(O.66 mg/g) was significantly increased as compared with $non-O_3$. Visual-growing characters of Sangnembatbyeo were significantly different between $0_3$ treatment and non-treatment. However, grain-filling rate showed no difference. SOD and POD related to resistant mechanism were high activity. In addition, phenylalanine known as precursor which is synthesized resistant materials was increased by $0_3$ treatment. These results suggested that Sangnambatbyeo which increased SOD and POD activity, and phenylalanine content under ozone stress could be selected as a tolerant variety.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.39 no.6
• /
• pp.526-530
• /
• 1994

This study was conducted to investigate photosynthetic response to four sequential air influx rate with rice(Oryza sativa L.)plants moved from a natural condition to constant condition with automatic regulation selected environmental variables on 13th~15th days after anthesis. In time course of photosynthetic response to increasing air influx rate(200-280-360-440 ml / min.), stomatal conductance decreased rapidly at the beginning after treatment and then oscillated with a free-running period of a approximately 1 hour to 1 hour 30 minutes until reached up to steady-state condition. Similar change was also observed $CO_2$ assimilation rate. Stomatal conductance decreased throughout the air influx rate sequence, but the rate of decrease was similar to the decrease in $CO_2$ assimilation rate observed under continuous air influx rate conditions. In starch granules during grain filling period under air influx rate(440 ml / min.) , compound starch granules were loosing and a number of hollows were observed in surface of single starch granules. Evidences from several approaches indicate that synchronization of stomatal conductance and$CO_2$ assimilation rate was closely inter-related tinder increase of air influx rate and increase of air influx rate influenced the$CO_2$ uptake in photosynthetic processes and compound starch granule, as 'end products' of photosynthesis.

• Applied Biological Chemistry
• /
• v.27 no.3
• /
• pp.169-173
• /
• 1984

In order to determine the optimum harvesting time based on grain filling and physico-chemical qualities for malting, three cultivars were harvested at every five days from 30th day after heading date at two experimental sites in the southern part of Korea. Starch accumulation and kernel weight increment were remarkable until 45th day after heading, but negligible after that. Content of ash, crude protein and polyphenolics and ${\alpha}-amylase$ activity decreased with maturation of grains and reached to the lowest value at 45th day after heading date. Germinative energy and capacity were good enough for malting from 40th day after heading date. The optimum harvesting time were estimated at 45th day after heading date in the increment of starch accumulation and kernel weight. At this time matured and immatured kernels were in the ratio 93 : 7. However, it is estimated that early harvesting time was at 40th day after heading date.

• Research in Plant Disease
• /
• v.9 no.4
• /
• pp.183-188
• /
• 2003

Correlation between the rice panicle blast and the rice quality and yield was evaluated in field experiments. Results showed that there were high positive correlations between the disease incidence and the rice yield and quality. The correlation coefficients between the disease incidence and the yield of Jinmibyeo, an early maturing cultivar and Juanbyeo, an middle maturing cultivar were $R^2$=0.6518 and $R^2$=0.7977, respectively. As the disease incidence increased weight of 1,000 grains of the two cultivars decreased showing coefficients $R^2$=0.6848 and $R^2$=0.7841, respectively. Percentage of matured grains in healthy plots were 95 and 98%, however, as the disease incidence increased percentage of matured rice grains decreased showing $R^2$=0.4745 in Jinmibyeo and $R^2$=0.703 in Juanbyeo. As the disease increased, rate of the damaged rice also increased, showing $R^2$=0.6607 in Jinmibyeo and $R^2$=0.6706 in Juanbyeo, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.31 no.3
• /
• pp.326-335
• /
• 1986

In cold water irrigation, some growth and yield were decreased by heavy application of nitrogen but in-creased by heavy application of phosphate, potassium and silicate. Among growth characters, number of spikelets per panicle and grain filling ratio were affected significantly. Cold damage in number of spikelets, spikelet sterility and degeneration of spikelet and branch could be reduced by increasing application amount of phosphate, potassium and in particular silicate. Number of spikelets per branch was closely related with number of spikelets per secondary branches. Number of abortive grains and immature grains had negative correlations with yield and could be reduced by heavy application of phosphate, potassium and silicate. Heavy nitrogen application led to high total nitrogen content and restrained the uptake of phosphate, potassium and silicate. However, adverse results were showed by heavy application of phosphate, potassium and silicate. Inorganic element contents in branches were lower than those in leaf blades, but higher than those in chaff. Branches showed little differences in inorganic element contents between heading stage and maturing stage. Inorganic element contents in branches were considered to be influenced by those in leaf blades and to affect those in chaff. Some growth characters related to source and sink, such as degeneration of branches and spike-lets, sterility ratio, ripening ratio, and yield had closer relationship with nutrient contents in branches than those in leaf blades and chaff. The results demonstrated that the rachis branch not only was a transport pathway of nutrient but also would play an important role in accumulating substances in panicles.