• Korean Journal of Weed Science
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• v.1 no.1
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• pp.44-51
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• 1981

An experiment was conducted to obtain the basic information about competitive ability of rice against weeds as affected by culm length at the Yeongnam Crop Experiment Station, Office of Rural Development in 1980. More weeds were harvested from the plot of short statured cultivar, Manseogbyeo compared to the plot of Cheongcheongbyeo that was approximately 10cm taller than Manseogbyeo regardless of planting density variables. Weeds also decreased as rice population increased from $30{\times}15cm$, $40{\times}(10{\times}10cm)$ and to $10{\times}10cm$, in order. The degree of weed suppression and floristic composition was varied depending upon plant spacing and weeding regime subjected at the previous year. The degree of weed suppression became increased with increasing rice population. The degree of weed suppression at the $10{\times}10cm$ plant spacing showed as high as hand weeding subjected in the previous year. However, in terms of floristic composition, Scirpus hotarui Roxb. became dominant when rice had cultivated at $10{\times}10cm$ plant spacing in the previous year while S. hotarui and Sagittaria pygmaea Miq. were both important in the hand weeding plot. The highest grain yield of rice showed at the $10{\times}10cm$ plant spacing while no significant difference was observed between $40{\times}(10{\times}10cm)$ and $30{\times}15cm$ plant spacings for both weeding regimes and both cultivars. However, response of grain yield to weeding regime was differed in two cultivars. For Manseobgyeo, significant grain yield decreased in no weeding plot regardless of plant spacing variables. But in case of Cheongcheongbyeo, grain yield reduction was only recognized at the $30{\times}15cm$ plant spacing. Based on these result it could be concluded that Cheongcheongbyeo (10cm taller in height) seemed to be more competitive against weeds than Manseogbyeo.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.1
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• pp.18-28
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• 2021

The growth period and productivity of cropping system of winter wheat-rice, winter wheat-bean and winter wheat-grain corn for 4 years from 2015 to 2018 were compared at the experimental field of National Institute of Crop Science in Miryang city. The harvest period of winter wheat was in mid-June, and summer crops were sown (transplanted) in late June. In transplanting of rice in late June, there was no difficulty in securing the heading of panicle and the yield of rice, but there was a lot of trouble in sowing wheat in proper time because the harvest time of rice was delayed to early November due to late maturity of rice, particularly in the mid-late maturing cultivar. There was no problem in soybean planting after winter wheat because the proper period of soybean planting is late-June. In addition, there was no problem in winter wheat sowng after soybean because the maturity period of soybean was mid-October. Selection of grain maize in double cropping with winter wheat in terms of growing periods, was desirable because grain maize had the fastest maturity among summer crops. In double cropping of winter wheat-summer crops, wheats combined with soybean and grain maize showed stable yields during three years, but there was a risk of yield declines in the wheat combined with rice in heavy rainfall year. It was possible to secure high yields in three summer crops as yields of rice, soybean, and corn were 600, 350, and 800 kg/10a, respectively. Summer crops with medium maturity was recommended because of no significant difference in yield between medium maturity and medium-late maturity cultivar. Soil physical properties were improved in soils cultivated with soybean and grain maize. Therefore, It was thought that double cropping systems of winter wheat with soybean and grain maize were superior to that of winter wheat with rice in terms of connecting period between winter wheat - summer crops and improvement of soil physical properties, and total income, particularly in soybean.

• Applied Biological Chemistry
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• v.9
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• pp.119-124
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• 1968

In order to learn the effect of timing and rate of potash fertilization in the rice plant nursery on the root growth and the vegetative growth of later stage a pot experiment was carried out employing 'Jaekun' a rice variety. Potassium Chloride was applied at the rate of $0{\sim}100g\;K_{2}O/3.3m^2$ right before, and 30 days after seeding. Forty-day old seedlings were transplanted three times successively at the one week intervals with the roots cut each time. Each subject was observed in rooting and other useful traits. A part of seedlings after the third root scission were cultured intact thereafter and the yield characters examined. The results were shown as: 1. The rate of sound seedlings was high in the case that a small amount of potassium was applied as the basic placement while the application of the fertilizer over $75g/3.3m^2$ (as $K_{2}O$) yielded a far less crops. 2. The plant height, number of tillers, number of leaves, and grass weight increased as the amount of potassium was elevated. However, the application of $50g\;K_{2}O/3.3m^2$ in the basic placement and that of $75g\;K_{2}O/3.3m^2$ were the peaks over which the above mentioned characters were weakened. 3. As the amount of potassium was increased the increment in number of rooting was notable, especially when the scission of roots was repeated within the limit of $50{\sim}75g\;K_{2}O/3.3m^2$. 4. In the maximum root newly shooted length indicated was about the same tendency although no statistical significance was observed. 5. The plant height, number of tillers, and variation of weight between grass and root indicated a similar tendency as the number of root shoot. 6. The differences in number of ears, grain yield, and weight of straw between the treatments were not so great but showed somewhat similar trend as in the growth of transplanted plants. In the treatment-100g $K_{2}O/3.3m^2$ the yield (ears, grain and straw) decreased as in the non-fertilized.

• Korean Journal of Weed Science
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• v.11 no.1
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• pp.11-18
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• 1991

Seven formulations of oxyfluorfen selected from the previous studies(4. 5) were tesed to evaluate crop injury and herbicidal efficacy on two rice cultivars and several annual and perennial weeds in a greenhouse. Each formulation at two different rates was applied to rice transplanted with 8-, 22- and 32-day old seedlings and to direct-seeded rice. Among the formulations, Elvan, Bentonite B. Chitosan and Coal Slag gave lower injury than a control formulation, Sand-coated oxyluorfen, and they did not have a problem with excessive release if active ingredient at once. Especially, the formulations of Elvan, Chitosan and Bentonite B controlled annual weeds (Echinochloa crus-galli, Monochoria vaginalis, Cyperus difformis., and Scirpus juncoides) and perennial weeds (Sagittaria pygmaea, and Cyperus serotinus). The surface structure of the formulations indicate the different possibilities of releasing of oxyfluorfen by different cracking and hole sizes, namely retention capacity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.483-488
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• 1993

This study was conducted to obtain the basic information for easily judgement to level of salinity stress of the reclaimed land. Rice varieties used were Nakdongbyeo and Chilsungbyeo. In seedling stage, 13 day-old seedlings were subjected to salt solution (0, 30, 60, 90mM) for 8 days. In reproductive stage, 30 day-old seedlings were transplanted 3 hills(3 seedlings /hill) per plastic pot (diameter 28${\times}$depth 30cm). Salinity stress was given by immersing pot in the salt solution(sea water) with 4 concentrations(0, 30, 60, 90mM)for 8 days at booting stage. The stomatal resistance was increased with salinity concentrations. Salinity stress appeared to be more sensitive in seedling stage than in reproductive stage in each concentrations. The photosynthesis was decreased in salinity treatment. Salt-treated periods influenced unfavorably stomatal resistance in each stages. The leaf chlorophyll content was remarkably decreased by increasing salt concentrations. The absorption of Na+ and Cl￣ were increased as salt concentration in the culturing medium became higher, but there was no appearent difference in the absorption of K+, Mg++, and Ca++. The plant height and root length were decreased in salinity treatment. The inhibitory effect of salinity stress on root growth was more severe than in shoot growth. The stomatal resistance could have been used as bio-information.

• The Korean Journal of Pesticide Science
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• v.8 no.2
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• pp.79-87
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• 2004

3-Chloro-2-[4-chloro-2-fluoro-5-(5-methyl-3-phenyl-4,5-dihydroisoxazol-5-ylmethoxy)-phenyl]-4,5,6,7-tetrahy dro-2H-indazole(EK-5439) demonstrated rice selectivity and herbicidal activity on annual weeds, such as Echinochloa oryzicola, Monochoria vaginalis, Lindernia pyxidaria, Rotala indica, Aneilema keisak, Cyperus difformis, and Ludwigia prostrata at doses of 16-63 g a.i./ha. However, the application window was limited from pre-emergence to 5 days after transplanting. The control efficacy of EK-5439 on barnyardgrass was 4 times higher than that of oxadiazon. EK-5439 was excellently safe to the 16 different transplanted rice cultivars treated 2 days after transplanting. These compounds have the mechanism of action on the chlorophyll biosynthesis like protoporphyrinogen IX oxidase inhibitors.

• Korean Journal of Agricultural Science
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• v.9 no.1
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• pp.231-238
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• 1982

The study was done to determine the proper transplanting dates and seedling ages of rice when mechanical transplanting was attempted. Heading dates of the Milyang #23, developed from Tong-il rice was delayed by delayed transplanting and the percent of filling grain was also low. The proper heading dates for the variety should be the first part of August and the transplanting should be done by the end of May. The presumed last days for the transplantation was considered early part of June. 30 to 40 days old seedlings were very effective to have healthy rooting systems. However, the Milyang #15 had shown more tolerance to the late transplantation than Milyang #23 and the degree of delaying heading dates due to the delayed transplantation was rather smaller than that of the Milyang #23. Even when the Milyang #15 was transplanted on June 30, the heading dates were around the middle of August and the ripening percentage was comparatively high and yield was also high. Therefore, the proper heading dates of the Milyang #15 might be around the middle of August and transplanting dates should be the first part of June. The possible last dates of transplantation of the Milyang #15 was assumed to be the last days of June and the proper seedling ages would be 20 to 30 day after sowing.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.5
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• pp.398-404
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• 1993

This study was conducted in order to obtain the information for yield improvement in saline paddy. Saline concentration, growth and yield of rice, being subjected to different flooding times and days to transplanting were investigated in saline paddy with 0.35 % and 0.5 % salt concentration. Saline concentration of soil was increased to 0.41 % just after rotary in the paddy with 0.35 % salinity, but decreased to 0.20 % after 3 to 4 times of flooding treatment. And also that of surface water was decreased from 0.2 % to 0.11 %. Saline concentration of soil in 5cm depth was decreased to 0.31 % by one time flooding and to 0.22% by 3～4 times flooding but salinity below 7cm depth showed slight decrease. Seedling death was exceeded 37 % when transplanted one day after rotary in the paddy with 0.35% salinity. Death ratio was decreased to 20% by three times flooding and transplanting six days after rotary. In paddy with 0.5 % salinity, death ratio was high but the tendency was very similar to 0.35 % field. In 0.35 % saline paddy field, yields were increased by 14 % by three times flooding and transplanting six days after rotary as compared to one time flooding and transplanting are day after rotary. Therefore, 3 to 4 times flooding and transplanting 5 to 6 days after rotary are desirable in high saline paddy.

• Journal of Plant Biotechnology
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• v.29 no.4
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• pp.247-252
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• 2002

The combination of radiation technique with an in vitro culture system was initiated to develop salt tolerant rice. We established an in vitro culture system to select tolerant lines against salt stress. NaCl tolerant cell lines were selected from the callus irradiated with gamma ray on N$_{6}$ medium with 1.5% NaCl and 2 mg/L 2,4-D. Regenerants (M$_1$) were obtained from the tolerant callus which was cultured for 30 days auxin-free medium. The M$_2$seeds were harvested from M$_1$plants on an individual plant basis. Thirty seedlings from each 450 M$_2$lines were transplanted in a field and total 5,000 M$_3$lines were harvested with an average 90 percent of fertile grain. M$_3$lines were utilized for selection of salt tolerance. Salinity-tolerant lines (225) were selected among 5,000 M$_3$lines. Of the 225 lines tested, the morphological traits of two lines (120-10 and -11) were far superior to control (Donagjinbyeo) in agromomic traits such as plant height, root length and no. of roots. Control and tolerant lines were analyzed by RAPD markers. Three polymorphic bands were presented in only tolerant lines, demonstrating a genetic difference between control and the tolerant lines. Such tolerant lines could be used as genetic resources to improve salt tolerance.e.

• Korean Journal of Weed Science
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• v.16 no.4
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• pp.317-326
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• 1996

To know whether pyrazosulfuron-ethyl(PYR) and imazaquin(IMA), known as a acetolactate synthase(ALS) inhibitors, have a same herbicidal action pattern in rice(Oryza sativa) or barnyardgrass (Echinochloa crus-galli), an inhibition pattern and a response characteristics in combination with dymron or butachlor were investigated. In contrast to the phytotoxicity of rice treated with IMA, the one treated with PYR was completely tended to be recovered after 25 days after treatment. Safening effect of dymron against PYR was effectively developed to transplanted-rice, while such an effect was not shown in combination with IMA. In combination with PYR and butachlor, antagonistic effect was observed in both simultaneous or sequential treatment on bamyardgrass, however, additive effect was rather shown in combination with IMA and its activity was dominantly dependent on the first applied compound. $I_{50}$ of PYR and IMA on the ALS extracted from barnyardgrass was $4{\times}10^{-7}$M and $2.8{\times}10^{-6})$M, respectively. Butachlor did not affect their activities on ALS in vitro. These results suggest that PYR and IMA might have a different action each other in the pathway to a final herbicidal activity even though their primary action site is ALS.