• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.6
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• pp.435-441
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• 2005

This experiment was conducted to identify the proper time of transplanting at Iksan plain area in Honam area from 2002 to 2004. The rice cultivars tested were Samcheonbyeo, Nampyeongbyeo and Hwaseong­byeo. The results are summarized as follows: The number of spikelets were most when transplanted on May 30 in all maturing types at southern plain. The ripened grain rates vary depending on location and transplanting dates. The proper time of transplanting for both of Samcheonbyeo and Nampyeongbyeo was between May 30 to June 9 and May 30 or later for Hwaseongbyeo. The highest head rice yield was obtained when transplanted on June 9 regard­Bess of the maturing types. The optimum transplanting dates according to maturing types with respect to the yield of head rice, ripened grain rates and the quality for both early and medium type was between May 30 to June 19, for mid-late type between May 30 to June 9.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.1
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• pp.22-27
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• 2005

To find out the optimum mixture ratio of ammonium and nitrate on rice plant, 4 rice varieties were examined during 14days after transplanting in hydroponics with the different ratio of ammonium to nitrate(100 : 0, 75: 25,50: 50, 25: 75 and 0: 100). The highest N uptake from solution and the maximum plant dry weight were $60\~70\%$ ammonium and $30\~40\%$ nitrate mixture treatment both in Japonica and Tongil type rice plants. And with the same varieties N-uptake and N use-efficiency were compared between 10.0 mM and 1.0 mM nitrogen using $70\%$ ammonium and $30\%$ nitrate for 24 days after transplanting. Rice plants absorbed more nitrogen$(131\~145\%)$ in 10.0mM than 1.0mM treatment but accumulated N in rice plants were almost the same in both treatment. Among the tested rice cultivars, dry matter production and total accumulative nitrogen in rice plants were much high in Tongil type than japonica type rice cultivars. N-recovery ratios of rice plants from uptake N were $90.8-99.0\%$ in low concentration N solution(1.0 mM), but $69.4-81.7\%$ were observed in high concentration N solution(10.0 mM). It means that suppling low concentration N steadily will be better to prevent loss of N without reducing of growth in rice plants.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.300-300
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• 2017

'Saemimyeon' a Tongil-type rice variety (Indica ${\times}$ Japonica), which contains high amylose contents is suitable for rice noodle production. Nowadays, the major parts of rice processing industry that includes products like rice flour and noodles are expected to partially replace wheat flour market. The volume of rice noodle market is getting bigger and can contribute to the rice surplus and farmer's income. This study was carried out to promote productivity and flour-making quality of 'Saemimyeon' by finding the most suitable transplanting and harvesting times. The transplanting days used were May $10^{th}$, May $17^{th}$, May $24^{th}$, May $31^{th}$, June $7^{th}$ and June $14^{th}$ and the planting distance used was 30 x 12cm. In addition, harvesting time was determined by days after heading time (40, 45, 50, 55 and 60 days). The field experiment was conducted at the experimental field in Miryang (Southern plain area of Korea) from 2015 to 2016. Our results suggest that the optimum transplanting days were from May $24^{th}$ to May $31^{th}$ which resulted to an average yield of 748~751kg/10a. Interestingly, yield was sharply decreased below 700kg/10a before May $10^{th}$ and after June $7^{th}$. The average grain filling rate before May $31^{th}$ was more than 83% but it declined to 75% after June $7^{th}$. The average temperature ranges from heading time to harvesting time was $ 21\sim25^{\circ}C$ and the estimated optimal temperature was $23.4^{\circ}C$ which is similar to May $24^{th}$ by regression equation. We found that the optimal harvest time was 45~50 days after heading time. It is hypothesized that low temperature at seed maturation time caused the lower grain filling rate therefore 'Saemimyeon' need to be transplanted before May $31^{th}$ for higher productivity. We found no statistical variation in amylose contents among experimental plots (28.2~30.4%). We conclude that the productivity of 'Saemimyeon' highly depends on temperature that is critical for grain filling stage controlled by transplanting time.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.345-350
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• 2006

Recently we have interest on rice products developed by environment-friendly management. The technology of paper mulching was practised without herbicide in machine transplanting cultivation of paddy. A field experiment was conducted on Gangseo series (coarse loamy, mixed, nonacid, mesic family of Aquic Fluventic Eutrochrepts) at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Republic of Korea in 2004. This experiment was carried out to evaluate rice growth, weed control and nitrogen efficiency by the different controlled-release fertilizer levels in paper mulching transplanting. Treatments consisted of conventional fertilization, controlled-release fertilizer (100%, 80%, 60%) compared with nitrogen amount ($110kg\;ha^{-1}$) of conventional fertilization and no nitrogen plot. Mulching paper consisted of recycled paper which was coated with biodegradable plastics. There were no differences between conventional rice transplanting and paper mulching on missing hills. Weed occurrence and control were diverse and low as fertilizer amount increased. Plant height and tiller number per hill increased as fertilizer amount decreased. There were no difference between controlled-release fertilizer 80% and conventional fertilization plot on rice growth traits. Leaf color and $NH_4{^+}-N$ in soil had similar trends. There was no difference in yield between controlled-release fertilizer 80% and conventional fertilization plot. Agronomic nitrogen-use efficiency was high as fertilizer amount decreased. Therefore, these results suggested controlled-release fertilizer 80% should be optimum amount under paper mulching transplanting of rice considering weed control, rice growth and nitrogen efficiency.

• Korean Journal of Weed Science
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• v.15 no.2
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• pp.105-114
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• 1995

Differences in critical period of weed competition were investigated among five types of rice(Oryza sativa L.) cultivation. Increase in weed-free period resulted in 1-2 days delay of heading date in machine transplanting and direct-seeding as compared with complete weed-free plot. When weedy period increased, there was no difference in heading date in transplanting cultivations. In direct-seeding, however, weedy period of 7-10 weeks after seeding(WAS) resulted in 4-7 days delay of heading date, whereas further increase in the weedy period caused rather 5-6 days advance in heading date. Weed-free period did not significantly affect yield components in conventional hand transplanting. In machine transplanting with 30-day-old seedling decreases in percent ripening and 1,000-grain weight were caused by weeds emerged within 4 weeks after transplanting(WAT). All yield components were decreased due to weedy period in machine transplanting with 10-day-old seedling. In direct-seeding weedy periods caused to decrease in number of panicles, number of spikelets, percent ripening, and 1,000-grain weight were 8-9, 4-5, 3-4, and 8-10 WAS, respectively. The critical periods of weed competition were determined as the following. In conventional hand transplanting weed-free must be maintained for either 4 weeks after transplanting or the rest period after 8 WAT. In machine transplanting with 30-day-old seedling weed-free must keep for either 5 weeks after transplanting or the rest period after 8 WAT. In machine transplanting with 10-day-old seedling weeds must be removed for either 5 weeks after transplanting or the rest period after 7 WAT. Weed-free must be kept between 5 and 7 WAS in flood direct-seeded rice and between 6 and 9 WAS in dry direct-seeded rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.4
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• pp.360-365
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• 1993

The infant seedling of rice(8-to 10-day-old) has often suffered from submergence just after transplanting due to the too short seedling height, 5 to 8cm, This experiment was conducted to elucidate the effect of gibberellic acid($GA_3 : 25% soluble liquid) with the application methods of foliar spray and seed-soaking on the elongation of seedling height of infant rice seedling in machine transplanting, We used a japonica rice variety, Hwaseongbyeo, and the seeding rate was 200g per seed tray(30$\times60$\times3cm). Generally,$GA_3 and Metalaxyl increased the elongation of seedling height of infant seedling while Tetracycle decreased the seedling height, To increase the seedling height of infant seedling, the foliar spary application of $GA_3 was better than seed-soaking treatment. The optimum concentration of $GA_3 for the foliar spray was about l0ppm and the optimum application time of $GA_3 was 3 to 4 days after sowing.

• International Journal of Contents
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• v.13 no.3
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• pp.1-8
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• 2017

Rice plant numbers and density are key factors for yield and quality of rice grains. Precise and properly estimated rice plant numbers and density can assure high yield from rice fields. The main objective of this study was to automatically detect and count rice plants using images of usual field condition from an unmanned aerial vehicle (UAV). We proposed an automatic image processing method based on morphological operation and boundaries of the connected component to count rice plant numbers after transplanting. We converted RGB images to binary images and applied adaptive median filter to remove distortion and noises. Then we applied a morphological operation to the binary image and draw boundaries to the connected component to count rice plants using those images. The result reveals the algorithm can conduct a performance of 89% by the F-measure, corresponding to a Precision of 87% and a Recall of 91%. The best fit image gives a performance of 93% by the F-measure, corresponding to a Precision of 91% and a Recall of 96%. Comparison between the numbers of rice plants detected and counted by the naked eye and the numbers of rice plants found by the proposed method provided viable and acceptable results. The $R^2$ value was approximately 0.893.

• Journal of Plant Biology
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• v.13 no.1
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• pp.1-12
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• 1970

The Nongkwang variety was sown directly in the field by the three methods of dibbling, drill seeding and broad-casting in non-, low- and high-salty areas, and compared with the growth of transplanted rice in each areas. The yield of rough rice was increased remarkably by direct sowing when compared with that produced by transplanting inboth salty areas, but in non-salty area, the former was decreased significantly. There was no significant difference in the yields of rough rice resulting from three seedling methods of direct sowing in each area. The direct sowing method was predominated in number of panicle, weight of panicle, ratio of matured grains, milling recovery percentage, and straw weight in both salty areas, and dicreased in panicle weight and ratio of matured grain in nonsalty area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.4
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• pp.441-448
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• 2012

This study was carried out to evaluate the productivity of rice cultivation in extremely late season in Korea and to confirm the effects of pot-raising seedling culture in this case by assessing the growth and yield performance of rice cultivars that are well adapted to late culture. Suitable cultivars for extremely late culture should not have premature heading habit when transplanted around late July and also secure appropriate growth duration before heading. Geumobyeo 1 and Manjongbyeo showed small decrease in the emerged leaves in transplanting in late July or early August and heading occurred at the same time relatively without premature heading. At transplanting from late July to early August in extremely late rice cultivation, ripening was relatively good until transplanting on August 5. At transplanting on July 30, accumulated temperature from heading to the first frost was $853^{\circ}C$ and ripening was good enough. However, heading was delayed by low temperature at transplanting on August 10 and ripening was very poor due to low accumulated temperature of below $800^{\circ}C$, causing drastic decrease of rice yield. The rice yield increased in transplanting with pot seedling, especially the effects of pot seedling was higher in Geumobyeo 1, but panicle number was not enough to secure rice yield owing to short growth duration. In order to cultivate rice in extremely late season, we should select adaptive rice cultivars that have suitable growth duration and excellent ripening in low temperature. Here, pot-seedling did a great role to secure early growth and bigger growth amounts.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.284-293
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• 2020

Rice consumption in Korea has been decreasing as the eating habits of the Korean people have diversified with rapid economic growth. Recently, floury endosperm rice cultivars were developed to boost rice consumption and replace wheat flour consumption with rice flour, which is vulnerable to viviparity under wet weather during the grain-filling stage because of its loosely packed starch granule structures. To overcome this limitation, it is necessary to find a suitable rice transplanting date to produce high-quality rice flour by altering the heading ecology type and changing the cultivation time by region. We examined four floury endosperm rice cultivars (FERC) in the Cheongju (central plain area) and Boeun (mid-mountainous area) regions of Korea from 2017 to 2019. Of the FERCs, the mid-late maturing types (MMT) Seolgaeng (SG), Hangaru (HGR), and Shingil (SGL) exhibited high yield and yield components after transplanting May 30 in both regions; the early maturing type (EMT) Garumi 2 (GRM2) also exhibited high yield after transplanting June 20 in Cheongju. In addition, MMTs showed the same tendency as the characteristics shown in Cheongju when grown in the Boeun region, and EMT displayed high yield and yield components after transplanting June 10. The FERCs could easily present pre-harvest sprouting in the rainy season during the grain-filling stage after 20 days post-heading because the mean temperature and frequency of more three-day rainfalls have increased over the last 5 years from the previous annual averages. Viviparity of HGR and GRM2 decreased as the transplanting date was delayed, with decreases of 2.3%-4.6% in HGR and 11.9%-23.1% in GRM2 according to the region. SGL was generally resistant to viviparity because of the Tongil type. To minimize pre-harvest sprouting and produce high yield of rice flour in the Chungbuk province, the most suitable transplanting time was the end of May in MMT and the middle and end of June in EMT.