• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.98-105
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• 1983

Differences in fertilizer responses of Chinese cabbage to soil water status were investigated in a field experiment. The growth pattern, water use, nutrient uptake, apparent efficiency of fertilizer and yield were analyzed under the 4-different fertilizer levels (N-P-K rate, kg/10a: 0-0-0 Fo, 11.5-10-12.5 Fo.5, 23-30-25 F1.0, 34.5-30-37.5 F1.5 and under the 4-different soil water status levels (non irrigated plot Mo, -0.1 to -1.0 bars M1, -0.1 to -0.5 bars M2, -0.1 to -0.2 bars M3). The soil was Bonryang sandy loam in the experimental farm of the Institute of Agricultural Sciences, Suweon. The growth and yield responses to the fertilizer levels showed a large difference between F0 and F0.5 but little differences were recognized between F0.5, F1.0 and F1.5 when the soil water potentials at 20-cm soil depth were lower than -2.0 bar. Under the well irrigated soil conditions, M2, and M3, the growth and yield responses to the fertilizer levels were significantly increased and the nutrient requirements were increased as well. The total uptake of nutrients decreased as the fertilizer amounts increased when the soil water potentials were low, while the total uptake of nutrients increased when the soil water potentials were high. Therefore, in considering nutrient availability of the applied fertilizers, the soil water status should be taken into account.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.2
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• pp.119-125
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• 1974

Uptake amount, percent translocation to grain and grain yield efficiency of N. P. K. Si were investigated with N. P. K simple trials (countrywide, 1967~69) and other nitrogen fertiltzer field trials in relation to yield class. 1) Uptake rate with yield increase were similar in all nutrients but silica showed greater yearly variation. 2) In N. P. K simple trials showing very low nitrogen efficiency(46kg grain/ nitrogen uptake kg) it and percent translocation increased with yield increase. 3) Nitrogen efficiency deacreased with the increase of nitrogen uptake and the decreasing rate depends greatly on fertilizer forms and variety. Nitrogen efficiency was greater in sandy loam where yield was higher than in clay loam. 4) Nitrogen efficiency positively correlated with percent translocation. 5) In high yielding fields yield was attributed only to the increase of nitrogen uptake, keeping efficiency around 50. 6) Major factor for high yield is considered as the increase of nitrogen efficiency rather than nitrogen uptake. 7) Phosphorus efficiency in N. P. K. simple trials was considerably low, suggesting too much uptake due to soil reduction.

• Research in Plant Disease
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• v.16 no.3
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• pp.285-289
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• 2010

The experiments were carried out in fields for two years from 2008 to assess yield losses of squash due to powdery mildew caused by Sphaerotheca fuliginea and to determine its economic thresholds. Powdery mildew disease was first observed in late June, about 50 days after field-transplanting, progressed rapidly during late July to early August, and began to reduce from late August. Powdery mildew severity was negatively correlated with squash yields. A positive correlation was observed between fruit weight and % marketable fruits. A simple linear regression model was obtained as Y=-10.399 X + 6607.5 with $R^2$ = 0.9700 when squash yields (Y) was predicted using powdery mildew severity as an independent variable(X). Spray threshold for maximizing squash yields without economic considerations was estimated as 6.5% in terms of leaf lesion area with powdery mildew. Economic threshold and economic spray threshold able to compensate the costs of fungicide sprays were determined as 21.6% and 17.3% in leaf lesion area, respectively.

• Korean Journal of Medicinal Crop Science
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• v.12 no.3
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• pp.231-236
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• 2004

Crop productivity would be determined by relative capacity of source and sink. The study was carried out to measure the effects of shading and flower bud pinching on growth and yield of Atractylodes japonica Koidz. Shading treatment after transplanting was done at 100%, 65, 45 or 25% level of natural light intensity but the pinching treatment was to remove all the inflorescences formed after June 10, July 10, August 10 or none. Growth and yield at early and late stages were periodically measured. At the early stage, shading mainly influenced fresh weight rather than morphological characters. At the late stage, however, severer shading decreased numbers of stems, leaves, roots, fraction and total fresh weight. 65% shading from July 1 to September 30 after skipped the emerging and early growth stages showed nearly same growth and morphological characters but more rhizome yield per unit area than non-shading. In flower bud pinching treatment, earlier pinching increased number of roots, fraction fresh weights per plant and rhizome yield per unit area.

• Korean journal of applied entomology
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• v.23 no.3 s.60
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• pp.153-157
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• 1984

The present work was designed to study the yield loss on rice at different appearance days of hopperburn caused by the brown planthopper(BPH), Nilaparvata lugens Stal, when rice plants were infested with BPH on booting and heading stages. Dead plants were colleted from 23 days after heading stage with intervals of 5 days. Yield losses by the initation of BPH infestation was greater at tooting than at heading stage. Compared to the uninfested plot, there was a reduction in 1,000 grain weight and filled grain percentage at both stages. Positive relationship was observed between rice yield(Y) and the number of days from heading to the appearance of the hopper-burn. Regression equations calculated were; for BPH feeding from booting $\hat{Y}(g)=10.145X-16.374(r=0.9726^{**})$, and for BPH feeding from heading $\hat{Y}(g)=9.792X+26.936(r=0.8850^{**})$.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.3
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• pp.134-141
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• 2005

Cultivation of winter cover crops and its soil utilization for summer main crops in slope upland is very important at the respects of diminution of soil erosion and non-point pollution source. The effects of cover crop, hairy vetch as no-tillage or conventional tillage on prevention of soil erosion and reduction of chemical nitrogen fertilization were investigated in the slope upland with whiter clover living mulch (partial tillage) in Suwon for three years and with rye (conventional tillage) in Hongcheon for two years, respectively. In Suwon, amounts of soil lost by rainfall runoff decreased as much as 90% by hairy vetch-no tillage (HV-NT), white clover-partial tillage (WF-PT) together with the decrease of rainfall runoff compared to winter fallow with conventional tillage (WF-CT). In addition, amounts of weed also decreased as much as 80-90% by HV-NT and WF-PT. Corn yield decreased much at the plot of WF-PT mainly due to competition for soil water and nutrients between clover and corn at the early corn growth stage. On the contrary, corn yield increased by HV-NT compared to WF-CT regardless of weed control. In Hongcheon, amounts of soil eroded during winter season before corn seeding were reduced as much as 95% by cultivation of hairy vetch and rye compared to winter fallow. Amount of soil eroded during waxy corn growing season was reduced as much as 98% by HV-NT compared to WF-CT. Also, soil incorporation of hairy vetch and rye as green manure with conventional tillage at corn seeding time could reduce soil erosion as much as 70% compared to no soil cover with conventional tillage. Ear yields of waxy corn were increased 10% higher at hairy vetch green manure (HV-CT) without nitrogen fertilizer, 20% higher at HV-NT with standard nitrogen fertilizer, respectively than WF-CT. But ear yields of waxy corn were decreased by rye green manure (R-CT) and HV-NT at the condition of no nitrogen fertilizer. It was concluded that hairy vetch was better as winter cover crop to reduce both soil erosion and chemical nitrogen fertilizer simultaneously in slope upland than other cover crops.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.11-18
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• 1984

The effect of transplanting method of rice seedlings on weed occurrence was investigated at the Yeongnam Crop Experiment Station in 1983. Rice was transplanted by hand and machine and eleven common herbicides were applied. The greatest weeds were harvested from the plot that rice was not transplanted and more weeds encountered at machine transplanted plot than hand transplanted plot. The degree of weed suppression by rice plant itself was 50% for machine transplatning and 55% for hand transplanting, respectively. Simpson index and community dominance of weed species were the highest in hand transplanting and followed by machine transplanting and no rice plot in order. Rice grain yield was exponentially correlated with the amounts of weed occurrence and more yield loss exhibited at machine transplanting than hand transplanting in the same amount of weeds. In the herbicidal activity, most of herbicides performed better at hand transplanting than machine transplanting while the degree of difference between transplanting methods varied depend on herbicide used.

• Korean Journal of Plant Resources
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• v.30 no.4
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• pp.427-434
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• 2017

This experiment was conducted to investigate the aspect of tiller occurrence, growth and yield of sorghum according to planting distance and sowing date. The object of this experiment is to get basic data to inhibit non-productive tillers uneconomical and cumbersome for mechanical harvesting. Also another object was to evaluate optimum planting distance and sowing date in central district area. Total number of tillers was more in 80 cm ridge than 60 cm ridge and it was increased as the planting distance was wider from 15 cm to 30 cm on the each ridge. Ratio of effective tillers was higher in 60 cm ridge than 80 cm ridge and it was decreased as planting distance was wider from 15 cm to 30 cm. The lower the planting distance, the more increased total number of tillers, whereas effective tillers was decreased as planting distance was high. Average of total number of tillers of three varieties was higher in sowing date of May 2 (1st sowing date), whereas ratio of effective tillers was the highest in sowing date of May 23 (2nd sowing date). Hwanggeumchal showed the highest total number of tillers (1.2 tillers), while Moktaksusu had the lowest total number of tillers (0.8 tillers) among three varieties. There were no significant difference between planting distance and days to heading and ripening date from seeding. Culm length increased as planting distance was high, but ear length, grains per ear and 1000 grain weight were decreased on the other hand. The highest yield of sorghum per 10a was obtained from $60{\times}20cm$ planting distance among 6 planting distances.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.4
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• pp.304-311
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• 1993

To find out suitable crops and their rotation years with rice for paddy-upland rotation, continuous rice cropping and rice with 1, 2 and 3 years cropping of upland crops(soybean, maize and job's tears) were tested for four years from 1989 to 1992. Rice yield, when averaged over rotation years for each crop, was increased ranging from 7% to 12% when compared with that of continuous rice cropping. With every crop, rice yield of 2 year upland rotation was higher than that of 1 year upland rotation, but rice quality seemed to deteriorate in paddy-upland rotation. When considering yields of the upland crops, 1 year rotation was the best condition for soybean and job's tears, with 3 years rotation being the best for maize. In paddy-upland rotation, number of weed species and its occurrence rates were reduced in paddy and upland condition and the reduction rates in paddy condition were higher than those in upland condition. Physical properties of soil were improved in paddy-upland rotation and airphase seemed to increase with increasing upland period.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.184-188
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• 2001

This study was conducted to find out the basic informations related to the rice cultivation using the infant seedlings. Infant seedlings with different nursery Periods were compared for the growth and grain yield of rice at the National Crop Experiment Station in 1997. The highest sound seedling ratio of 93.9% was observed in 8-day old seedling, followed by 88.9% of 12-day, 82.0% of 16-day, and 80.8% of 20-day, The endosperm remained 52.5% in the 8-day old seedling at transplanting and decreasingly with increasing nursery period. Missing hills at transplanting were more in 16-day and 20-day old seedling than in 8-day and 12-day old seedlings, 5.1-5.2% in 8-day and 12-day growing seedling, 6.7% in 16-day and 7.8% in 20-day old seedling. Rooting ability was observed highest in 8-day, followed by 12-day, 16-day and 20-day old seedling. The milled rice was lower by 5-16% in 12-day, 16-day and 20-day old seedling than in 8-day old seedling of 6.18 t/ha. It was found that the 8-day and 12-day old seedling provided more advantage for sound seedling ratio, endosperm remaining, missing hill during transplanting, rooting ability and grain yields than 16-day and 20-day old seedlings.