• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.4
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• pp.373-381
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• 1999

Six soybean cultivars having different SDS susceptibility were planted with sorghum seedinoculum infested with F. solani isolate 171 in the greenhouse. First leaf symptoms appeared on unifoliar leaves at 9 days after inoculation and all cultivars showed the typical leaf symptoms at 13 days after inoculation, when trifoliar leaves emerged. Leaf symptoms development in susceptible cultivars was faster than in resistant cultivars. Leaf symptom severities during the period of 25 to 29 days after inoculation showed a significant difference between cultivars which had SDS resistance and sus ceptibility. In this period, area under the diseaseprogress curve (AUDPC) of Hartz 6686 was the highest and that of PI 520733 was the lowest. SDS caused serious damage to the growth of soybean in all cultivars. Average reductions of growth rate of root fresh weight and dry weight were greater than those of plant tops. Duyu-kong showed less severe leaf symptoms than that of SDS suscetible cultivars; however, average growth rate of plants top and roots of this cultivar was less but not significantly different than those of SDS susceptible cultivars. In all cultivars, as severity of leaf symptoms increased, plant top weight decreased. Root rot symptoms were observed in all cultivars before leaf symptoms appeared. Average proportions of tap root reddish-brown discoloration of all cultivars was up to 75 % at 15 days after inoculati on; however there was no significant differenc between cultivars at each rating date. Appearances of leaf symptoms on leaves varied in each cultivar. SDS resistant cultivars had a significantly higher level of crinkling than susceptible cultivars and SDS susceptible cultivars had a significantly higher level of necrosis than resistant cultivars. Further study will be needed to identify the relationships between the physiological growth rate and SDS severities in soybeans.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.6
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• pp.723-730
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• 1995

Effects of leaf and pod removal on changes in dry weight and protein content of soybean [Glycine max (L.) Merr.] cultivar 'Hwangkeumkong' were measured at the research farm of Korea University in 1992. The upper 40% and lower 60% of leaves and pods were subjected to treatments at the growth stage of beginning pod(R3). Leaf dry weight of lower part was increased by upper leaf-lower pod removal, but seed dry weight of upper part was decreased. The upper leaf-lower pod removal also increased stem dry weight and decreased upper pod dry weight. Protein content was higher in lower leaves than upper leaves. Seed protein contents were decreased both upper leaf-lower pod removal and lower leaf-upper pod removal treatments. The upper leaf-lower pod removal showed the highest leaf and the lowest seed protein quantities among the five treatments. These results indicated that protein sources were moved from lower to upper parts but weak in remobilization from leaves for the long distance translocation during the reproductive growth period of soybean plants.an plants.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.6
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• pp.594-601
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• 1994

Effects of translocation on seed yield and carbon-nitrogen compounds at five leaf-pod ratios of soybean [Glycine max. (L.)Merr. ] culti bars, 'Paldalkong', 'Baekunkong', and 'Danyeobkong' were measured. The upper 50 and lower 50% of leaves and pods were subjected to treatments at growth stage R3. Three soybean cultivars showed the similar trends on changes in dry matter accumulation and on the contents of soluble sugar, starch and protein in seeds among the treatments. Mean stem dry weight was increased with upper leaf-lower pod and lower leaf-upper pod removals, and decreased with upper leaf and lower leaf removals. Leaf dry weight was appeared higher at the upper leaves among the treatments. Seed numbers and dry weights were decreased with leaf and leaf-pod removals, and were higher in lower part of the plants. Soluble sugar and starch contents in seeds were also showed slightly higher in lower part. Protein content of seeds was decreased in upper part with upper leaf removal and in lower part with lower leaf removal, however, that of the upper seeds was the highest with lower leaf removal. The results of this study are assumed that carbon and nitrogen compounds were translocated opposite directions and protein source was weak in remobilization for the long distance transport during the reproductive growth period of soybean plants.

• Korean journal of applied entomology
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• v.41 no.2
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• pp.85-89
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• 2002

Development and reproduction of the rice armyworm, Pseudaletia separara, were investigated on different diets (corn leaf, rice leaf, Chinese cabbage leaf, cabbage leaf, sweetpotato leaf, soybean leaf and silkworm artificial diet). Egg and pupal periods were not different among the diets. But larval periods showed significant difference among diets. Developmental period from egg to adult was shortest as 32.5 d on corn leaf and longest as 46.6 d on soybean leaf. At 16 days after hatching, larval weights on rice and silkworm artificial diet were heavier than those on other diets. The larvae reared on cabbage leaf and sweetpotato leaf failed to pupate. Survival rates from larva to adult were highest (70.6%) on com leaf lowest (39.8%) on soybean leaf. The longevity of female adults was not affected by the larval diets. Female adults showed higher fecundity when the larvae were fed with corn leaf, rice leaf and silkworm artificial diet than other diets. Net reproduction rate (R$_{0}$) was highest as 1218.5 on silkworm artificial diet. The intrinsic rate of natural increase (R$_{0}$) ranged from 0.115 to 0.175, and was maximum on com leaf.

• Journal of Life Science
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• v.8 no.4
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• pp.437-442
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• 1998

Seed and leaf size is the important morphological traits considered by plant breeder and is the important yield components in soybean. The objective of this research was to know the relationship between seed size and leaf size in 66 $F_2$ populations derived from half diallel mating system with 12 soybean strains, representing distinct seed and leaf size. The range of seed size for 12 parents used was 6.7 to 43.8 g/100 seed. Leaf width leaf length ranged 5.7 to 8.6 cm and 9.4 to 12.9 cm, respectively. Leaf width was highly correlated with leaf length with an R square of 0.754 in the $F_2$ generation. The $F_2$ regression` coefficient indicated that leaves were, on average 1.4 times greater length than in width . Leaf size (width) was highly correlated (r.0.91) with seed size (g/100 seed) in the $F_2$ generation with an R square of 0.833. Our results indicate postive correlation within seed and leaf size is common in $F_2$ segregating populations derived from crossing with soybean. The strong liner relationship we observed between leaf size and seed size in $F_2$ segragating population is useful in that in that indirect selection for a secondary character may be superior to direct selection for the primary character.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.3
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• pp.137-145
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• 1981

The mutual effects of calcium, potassium and boron on the growth of the leaf lettuce and its following crop of soybean in the granite soil were observed. The results obtained were as follows : 1. The yields of leaf lettuce and soybean were greatly increased by the application of calcium. It was observed that the calcium content in soybean leaf correlated positively with the yields, the number of pods and dry weight of soybean. 2. The application of calcium was effective by itself on the plant growth, the Ca+B application was better effective, and the best effective plot was $Ca+B_1+K_1$. 3. No significant tendency was observed between the Ca/B ratio in plant tissue and its growth. 4. The application of boron increased calcium absorption in plant tissue regardless of the application of calcium. 5. The number of pods and 100 grains weight of soybean were increased by the application of boron, And a positive correlation was observed between the boron content in soybean leaf and the number of pods of soybean. 6. One basal application of calcium, potassium and boron was effective both on leaf lettuce and on its following crop of soybean.

• Journal of Life Science
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• v.8 no.5
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• pp.492-496
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• 1998

Intact measurement of leaf water content was attempted using the transmission of beta radiation. Prior to the experiments, two tested plants, rice and soybean, were grown in 1/5000a wagner pot. The moisure ratio of plant leaves were measured with the beta radiation transmission method using a G-M detector and $^{99}$ Tc as the beta ray sou-rce. Beta radiation transmission showed a tendancy to increase with the passage of time after leaf cutting. However, it showed a tendancy to decrease with water supply for the lack of water. A positive correlation was found between the leaf water content and beta radiation transmission. The mutiple regression analysis about leaf water content was obtained that the coefficient of partial regression for beta radiation transmission was much higher(rice; -0.863, soybean; -0.904) than that for specific leaf area(rice; 0.007, soybean: 0.004).

• Research in Plant Disease
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• v.19 no.3
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• pp.196-200
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• 2013

This study was carried out to investigate yield loss due to soybean leaf spot disease caused by Cercospora sojina Hara and to determine the economic threshold level. The investigations revealed highly significant correlations between disease severity (diseased leaf area) and yield components (pod number per plant, total grain number per plant, total grain weight per plant, percent of ripened grain, weight of hundred seed, and yield). The correlation coefficients between leaf spot severity and each component were -0.90, -0.90, -0.92, -0.99, -0.90 and -0.94, respectively. The yield was inversely proportional to the diseased leaf area increased. The regression equation, yield prediction model, between disease severity (x) and yield (y) was obtained as y = -3.7213x + 354.99 ($R^2$ = 0.9047). Based on the yield prediction model, economic injury level and economic threshold level could be set as 3.3% and 2.6% of diseased leaf area of soybean.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.4
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• pp.325-330
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• 2004

This study was carried out to determine adequate planting date, to compare the growth characteristics between early and late maturing cultivars, and to provide the data for the cultivation techniques of soybean [Glycine max (L.) Merr.] in double cropping system with winter crops on paddy field in Korea. Cultivars were planted on 26 May, 16 June, and 7 July with a planting density of $70cm(row\;widtb)\;{\times}\;10cm$ (planting spacing). Seed yield of soybean planted on June 16 and July 7 was approximately $37\%\;and\;53\%$, respectively, less than that of conventional planting date of May 26 in Pungsan-namulkong, and planted on June 16 and July 7 was about $30\%\;and\;37\%$, respectively, less then that of conventional planting date of May 26 in Hanamkong. The number of pods and seeds per plant decreased as planting date delayed. Seed weight increased in Pungsan-namulkong but decreased in Hannamkong as planting date delayed. The flowering date was late in delayed planting plots, but it was shorted for days from emergence to flowering and from emergence to maturity. The plant height of Hannamkong was greater than Pungsan-namulkong from the emergence to flowering stages, but in contrast, it was greater in Pungsan-namulkong than Hannamkong after flowering stage (50d after emergence) when it planted on May 26. There were no significant differences between two soybean cultivars at planting dates of June 16 and July 7. Leaf number, leaf area, and dry matter were also reduced by late planting, and Both of them were shown in high reduction at the later planting. There was a high significant difference at the flowering $(r\;=\;0.87^{**})$ and pod formation $(r\;=\;0.91^{**})$ stages between leaf dry matter and seed yield. Crop growth rate (CGR) was greater at $R2\~R3$ growth stages compared to $R3\~R4\;or\;R4\~R5$ growth stages in two soybean cultivars and the greatest CGR was obtained at planting date of May 26 in two soybean cultivars except for R4-R5 growth stage in Pungsan-namulkong. There was a highly significant positive difference between the seed yield and the leaf area index (LAI) across R3 to R4 and R2 to R3 stages. The photosynthetic rate $(P_N)$ of the uppermost leaf position had no significant difference among planting dates and between two soybean cultivars. However, $P_N$ of the $7^{th}$ leaf position increased as the planting date delayed.

• Korean Journal of Organic Agriculture
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• v.22 no.4
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• pp.773-787
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• 2014

Bacterial pustule of soybean caused by Xanthomonas axonopodis pv. glycines is one of the most prevalent bacterial diseases in many areas where soybeans are grown. This study was carried out to evaluate the effect of cultivars, sowing date and cropping system on the suppression of soybean bacterial pustule in the field. One hundred soybean cultivars were screened for disease resistance against bacterial pustule in naturally infested field. Among them, fourteen cultivars including 'Pureun' were found to be high resistant. And thirty cultivars showed to be moderate resistant(less than 3% of diseased leaf area). When Soybean cultivar 'Taekwang' were sown in four different dates, May 25, June 5, June 15, and June 25, at 10 day-interval in Milyang, the diseased leaf area of bacterial pustule was 23.3%-25.7%, 14.7%-18.0%, 10.7%-12.8%, and 1.0%-2.7%, respectively. The lowest percentage of diseased leaf area was recorded in the plots sown on June 25, whereas the highest percentage of diseased leaf area was recorded in the plot sown on May 25. As sowing time was delayed, incidence of soybean bacterial pustule found to be comparatively reduced. From December in 2006 to June in 2007, we surveyed the pathogen population of soybean bacterial pustule in five cropping upland soils where soybean was cultivated. The survey result showed the bacterial pustule pathogens were detected from the all cropping soils. The pathogen populations of soybean bacterial pustule in soybean-barley and soybean-garlic cropping soil were significantly lower than that of the other cropping soils. In addition, the incidence of soybean bacterial pustule was decreased under the two cropping systems.