• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.1-6
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• 2004

N fertilizer required by rice could be reduced greatly in the rice-barley double cropping system than in the rice single cropping system. This study was conducted to investigate how much of the N fertilizer during the early stage of rice in the rice-barley double cropping system, could be saved compared to that in the rice single cropping system. This experiment was carried out at the paddy field of the National Crop Experiment Station in Suwon, Korea during three years from 1999 to 2001. Amounts of soil mineral nitrogen (SMN) and SPAD values of rice leaf during rice growing season in the rice-barley double cropping system were higher than those in the rice single cropping system under the same amount of N application during two years. Yield and N uptakes of rice at harvesting time were also higher in the rice-barley double cropping system than in the rice single cropping system during two years. Yield and N uptake of rice in the rice single cropping system were decreased when basal N fertilizer was omitted, but those reductions were not found by either omitting basal N fertilizer or omitting N fertilizer at tillering stage in the rice-barley double cropping system during 2000 and 2001. But yield and N uptakes of rice were decreased by 70 kg/10a and 2kgN/10a by the omission of both N application at basal and tillering stages in the rice-barley double cropping system in 2002. It was concluded that N fertilizer as much as tillering N fertilizer could be saved in the rice-barley double cropping system.

• Journal of Environmental Science International
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• v.30 no.8
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• pp.659-671
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• 2021

The physicochemical properties of soil and the yield and quality of rice (Oryza sativa L. cv. Sailmi) were assessed using Italian ryegrass (Lolium multiflorum Lam. cv. Kowinearly)-rice double cropping systems in the paddy fields at Goseong and Miryang in southern Korea. The average temperatures during the ripening period were approximately 1 ℃ higher than the optimal temperature for rice ripening and the sunshine duration was reduced by frequent rainfall. Consequently, it was slightly below the optimal conditions required for rice ripening. In the soil at Goseong, winter Italian ryegrass cropping increased the pH, electrical conductivity, and the contents of organic matter, total nitrogen (T-N), available P₂O₅, K, Ca, and Mg than winter fallowing. Particularly, the contents of T-N and available P₂O₅increased significantly. In the soil at Miryang, Italian ryegrass slightly increased the electrical conductivity and the T-N, Mg, and Na contents. Therefore, winter Italian ryegrass cropping improved the physicochemical properties of paddy soils; however, Italian ryegrass-rice double cropping slightly reduced the culm length at both Goseong and Miryang, without markedly changing the panicle length or number compared to fallow-rice cropping. Furthermore, at Goseong, Italian ryegrass-rice double cropping slightly decreased the spikelet number and milled rice yield, and increased the ripened grain rate; however, at Miryang, contrasting results were observed. In addition, fallow-rice cropping revealed no differences in the head rice or opaque rice rates. The protein content was slightly increased in Italian ryegrass-rice double cropping, without significant changes in the amylose content or Toyo value, compared to that in fallow-rice cropping. The peak and breakdown viscosities were slightly decreased. These results indicate that winter Italian ryegrass cropping might alter rice taste but may not exhibit remarkable negative effects on rice cultivation. Therefore, Italian ryegrass-rice double cropping system is recommended for paddy fields in southern Korea. Nevertheless, to increase the rice yield and quality, fertilization standards for rice cropping that consider the changes in the T-N and organic matter contents in paddy fields caused by winter Italian ryegrass cropping need to be established.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.47-47
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• 2017

Rice cropping in Cambodia was commonly classified into 4 types: rainfed rice, irrigated rice, floating rice and recession rice. The cropping type has been selected by farmers depended on water condition in each locations. However, recent technological and social change enforce famers to adapt new management of rice cropping. This study aimed to clarify the change in rice cropping and problems for future. Interviews to farmers has been conducted several times in Pursat province, which is one of the major rice production provinces in Cambodia. The last interview was conducted in March 2017, and focused on change in rice cropping for 10 years. Statistical data was obtained from Provincial Ministry of Agriculture in Pursat. The satellite data (LAI products derived from MODIS) was used to quantify change in cropping pattern. The statistical data shows increase in production and yield of rice, dry season rice and so on.

• Journal of Environmental Science International
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• v.31 no.5
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• pp.413-422
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• 2022

To identify rice (Oryza sativa L.) cultivars suitable for Italian ryegrass (Lolium multiflorum Lam.)-rice double cropping systems, we investigated the yield and grain quality of four different midseason maturing rice cultivars ('Daebo', 'Haepum', 'Haiami', and 'Samdeog') and four midseason-to-late maturing rice cultivars ('Hyunpoom', 'Saeilmi', 'Saenuri', and 'Samkwang') in single rice cropping and Italian ryegrass-rice double cropping systems in paddy fields of Miryang, South Korea. We found that organic matter and available P₂O₅ content slightly decreased, whereas Na content increased, in the soil where Italian ryegrass was cultivated during winter compared to that in the soil that remained fallow during winter. The pH, electrical conductivity, organic matter, and contents of K⁺, Ca²⁺, Mg²⁺, and Na⁺ decreased, whereas the available P₂O₅ content slightly increased, in the soil where rice was harvested in both single and double cropping systems. However, compared to the optimum soil conditions for rice cultivation, available P₂O₅ and K⁺ content were high and Mg²⁺ content was low in both single and double cropping systems. At the heading stage, the culm length and leaf color slightly increased in most of the rice cultivars, whereas the panicle length and number slightly decreased, in the double cropped system. After harvesting, spikelet number and milled rice yield did not show a significant difference between single and double cropping systems. However, the ripened grain rate and weight per thousand grains increased slightly in the 'Saeilmi' and 'Samkwang' cultivars but remained either stable or slightly low in other cultivars in the double cropping system. The milled rice yield was high (> 500 kg/10a) in 'Daebo' and 'Haepum' among midseason maturing rice cultivars, and in 'Saeilmi' and 'Saenuri' among midseason-to-late maturing rice cultivars, in both single and double cropping systems. The head rice rate was high in midseason maturing rice cultivars in the double cropping systems, reaching > 70% in 'Haepum' and 'Haiami' cultivars, whereas it decreased in most midseason-to-late maturing rice cultivars (excluding 'Samkwang' cultivar), in double cropping systems. Particularly, it exceeded > 70% in the 'Saenuri' cultivar in both single and double cropping systems. The protein content in milled rice increased, whereas the amylose content either remained stable or slightly increased, in double cropping systems. The Toyo taste value decreased in all midseason-to-late maturing rice cultivars and slightly increased in the 'Daebo' and 'Haiami' cultivars among midseason maturing rice cultivars in double cropping systems. However, Toyo taste values in the 'Haepum', 'Haiami', and 'Saenuri' cultivars exceeding > 80% in both single and double cropping systems. Therefore, we recommend 'Haepum', 'Haiami', and 'Saenuri' cultivars as candidates for Italian ryegrass-rice double cropping systems due to high yield, head rice rate, and Toyo taste value.

• Korean Journal of Agricultural Science
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• v.45 no.3
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• pp.355-363
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• 2018

This study was conducted to investigate suitable rice cultivars for various rice based cropping systems in a paddy field in the Yeongnam plain area. Thirteen rice cultivars (5 early, 3 medium and 5 mid-late maturing cultivars) and three transplanting dates (June 5, June 25 and July 5) were evaluated in this study. The mid-late and early maturing cultivars for the July 5 and June 25 transplanting headed before August 30 which is the safe heading date in the Yeongnam plain area, ranging from Aug. 26 - 28 and Aug. 18 - 23, respectively. The safe harvest time of rice for double and triple cropping systems should be before the middle of October for the cultivation of the succeeding winter crops. The rice yield was the highest for the June 5 transplanting regardless of the rice cultivars, and it gradually decreased as the transplanting date was delayed from June 5 to July 5 due to a decrease in the spikelet numbers per panicle number and in the ripened grain rate. In contrast, the other yield parameters that include the panicle number per $m^2$, the 1,000-brown rice weight, and the ripened grain ratio were not significantly affected. The result indicates that based on the milled rice, heading time and harvest time, a medium maturing cultivar (Haiami and Samdeog) would be applicable to a winter barley/wheat, garlic/onion-summer rice double cropping, while a mid-late cultivar (Saeilmi, Saenuri and Hyunpoom) would be suitable for a spring potato/waxy corn-summer rice double cropping in the Yeongnam plain area. On the other hand, an early maturing cultivar (Unkwang, Jokwang and Haedamssal) would be preferable for a triple cropping because of the short growth period of rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.84-91
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• 2006

This study was carried out to comparatively evaluate growth characteristics of rice cultivars under rice-mono (conventional) and rice-Chinese milk vetch (Vetch) cropping system. Six rice cultivars such as Geumobyeo, Pungmibyeo, Hwayeongbyeo, Sobibyeo, Junambyeo and Dongjinbyeo were tested in 2005. The results obtained are summarized as follows ; plant height and culm length of all the tested cultivars at heading and harvest time were shorter in rice-vetch cropping system than conventional, however, nitrogen content of rice plants at heading and harvesting time was higher in rice-vetch cropping system. The total amount of nitrogen of rice plants was higher in conventional than rice-vetch cropping system. Nitrogen content of rice plant and uptake of Pungmibyeo was the highest of all the tested cultivars in both cropping systems. Generally, grain yietd ef tested cultivars seemed to be higher in conventional than rice-vetch cropping system. And it was the highest in Junambyeo as compared to those of other cultivars. Head rice ratio and protein content were higher in rice-vetch cropping system.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.297-306
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• 2021

To select rice (Oryza sativa L.) cultivars suitable for forage-rice double cropping system, the growth and grain quality of four early maturing rice cultivars (Joun, Jopyeong, Haedamssal, and Unkwang), and the chemical properties of soils were investigated under single- (fallow-rice) and forage-rice double-cropping systems in paddy fields in Miryang, southern Korea. The soil where two forage crops [Italian ryegrass (Lolium multiflorum Lam.) and oat (Avena sativa L.)] were cultivated during winter had a slightly lower pH; an increase in total nitrogen (T-N), K, Ca, and Na contents; and a slight decrease in organic matter and available P₂O₅ contents, compared with the soil fallowed during winter. This shows that the chemical properties of paddy soils can be improved by winter forage cropping. At the heading stage, the culm length, panicle length, panicle number, and leaf color of all cultivars, except for Haedamssal, were generally higher under double-cropping than under single-cropping. For Haedamssal, the culm length and leaf color did not differ between the cropping systems, but the panicle length was slightly shortened and its panicle number increased under double-cropping. After harvest, the yield of milled rice decreased for all cultivars except Haedamssal, but increased in Haedamssal under double-cropping. The head rice rate was slightly higher under double cropping, particularly in Jopyeong and Haedamssal, than under single-cropping. The protein content of milled rice under double cropping was higher and its amylose content was similar or slightly lower compared to those of rice under single cropping, resulting in decreased Toyo values for rice under double-cropping. The pasting temperature did not differ significantly between the cropping systems. However, Haedamssal had a low pasting temperature but a high Toyo value under double cropping, compared to the other three cultivars, suggesting that its palatability is relatively high. Furthermore, panicle number increased and milled rice yield did not decrease, even under double cropping. Therefore, Haedamssal seems to be the best cultivar for paddy-based double cropping with forage crops.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.4
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• pp.413-416
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• 2008

The cultivation of green manure crop is considered as a good management practice by increasing soil organic matter and fertility levels. This experiment was conducted to improve the soil environment under rice-based cropping system at paddy soil (fine loamy, mixed, nonacid, mesic, family of Aeric Fluventic Haplaquepts) in National Institute of Crop Science (NICS), Korea in 2006 to 2007. The variation of soil temperature in green manure plots was lower than without green manure (control) during spring season (April to May). The temperature variation of no tillage plot (broadcast before rice harvest) was the lowest among treatments. After green manure cropping, the soil bulk density and porosity ratio were improved at the top soil. The production of green manure was the highest athairy vetch and barley mixture plot by partial tillage. However, mixture treatment had no improvement on soil organic matter. After rice cropping with green manure application, soil quality was improved such as soil physical properties except mixture treatment. Therefore, we suggest that soil quality should be improved by green manure cultivation under rice-based cropping system.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.4
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• pp.351-356
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• 2009

Growth, milled rice yield and edible quality of rice in naturally reseeded Chinese milk vetch(CMV)-rice cropping system was compared with those in rice mono cropping on silty loam soil in Milyang from 2006-2008. Practicing natural reseeding technology recorded high CMV reseeding stand ranging from 565-805 plants $m^{-2}$ and resulting in the production of 13.0-17.0 kg N/10a from the CMV plant biomass which is greater than the recommendation rate of 9 kgN/10a. The plant height of rice plant grown in natural reseeding field is shorter at tillering stage but it was similar to the rice mono cropping at later stage. Dry matter production had similar trend to plant height. On the other hand, the leaf color in naturally reseeded CMV-rice cropping system was similar to the rice mono cropping up to panicle heading stage but it was high at mature stage, indicating that the nitrogen was provided by the CMV decomposition until later stage of rice. The yield components such as culm number $m^{-2}$ was greater and 1,000-brown rice weight was heavier than those of rice mono cropping but the ripened grain ratio was lower in naturally reseeded CMV-rice cropping system. Milled rice yield of naturally reseeded CMV-rice cropping system was similar to that of rice mono cropping. However, head rice percentage of milled rice was lower due to low ripened grain ratio. This result indicates that natural CMV reseeding technology can completely replace chemical fertilizer in CMV-rice cropping system.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.221-224
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• 1999

A field experiment was carried out to observe the weed control effects of vetch and to evaluate vetch characteristics on clay loam soil in no-till direct-sown rice-vetch cropping systems. The effects of weed control, forage productivity, and N content of vetch plants were investigated. With the progress of plant growth, density of Chinese milk vetch (Astragalus sinicus L.) gradually decreased, but densities of foxtail and other weeds decreased steeply due to the depression by the over-shaded vetch canopy in a no-till direct-sown rice-vetch cropping paddy field. The vetch density in tillage systems was lower than in notillage cropping systems. Lower vetch density occurred with an increase in foxtail density and other weeds. Weed control effect increased by the progress of vetch growth, which indicated that the vetch canopy over-shaded the weeds. Vetch straw was degraded rapidly submergence after with water at the time of wet sowing of rice. Early harvesting of vetch seed resulted in lower seed germination. To acquire enough seedlings without re-sowing, the harvesting of seed should be delayed at least 28 days after the flowering stage in order to ensure the vetch population is sustainable in a no-till direct-sown rice-vetch cropping system. In order to improve the survival of vetch plants, vetch seeds should germinate from the heading .stage to before the full-ripening stage of rice plants. To enhance the percent of over-wintering survival, vetch seeds should germinate no later than the end of October in southern Korea. The dry weight of vetch plants increased with the progress of vetch growth until the flowering stage but N content decreased for 30 days from before the flowering stage (2.9%) until the ripening stage (1.8%). We concluded that Chinese milk vetch could have an effect on weed control before the flowering stage, sustainability without re-sowing of seed annually, and effective green manure for rice pre-crop in no-till direct-sown rice-vetch relay cropping systems.