• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.1
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• pp.25-30
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• 1987

There are differences in opinion as to whether nitrogen fertilizer should be used when establishing alfalfa (Medicago sativa L.). Various reports show that under a hot environment, rhizobia (Rhizobium meliloti) are not as effective in fixing atmospheric nitrogen as they are under moderate temperatures. It is also believed that the addition of nitrogen fertilizer inhibits nodulation of alfalfa seedlings. A replicated experiment was conducted under controlled environmental conditions at the University of Nevada-Reno, Reno, Nevada, USA, to determine the effects of nitrogen application on seedling growth and nodulation of alfalfa grown in a hot environment. Sterile sand was used as the growing media to which a complete nutrient solution minus nitrogen was applied volumetrically to each pot daily. In addition, half of the pots received NH4-$NO_3$, at the rate of 11.2 kg per ha at seeding and at two and four weeks after planting giving a total nitrogen application rate of 33.6 kg per ha during the seven-week experimental period. Rhizobia inoculant (R-12) consisted of a mixture of strains 171-15a, 1682c and 80 PI 265 of (Rhizobium meliloti). Inoculant was applied to the seeds prior to planting and to the sand media at two and four weeks after seeding. Twenty seeds were planted in pots 14.0 cm in diameter and 11.5 cm deep. Plants were thinned to ten plants per pot after emergence and were grown in a controlled environment chamber with a 16-hour light period. Soil temperature at 6 cm depth ranged from 17.4^{\circ}C.$ to 31.1^{\circ}C.$ and had a daily mean of 26.5^{\circ}C.$. Plants were harvested at weekly intervals for seven weeks. Root, shoot and total length, dry weight, volume and number of nodules per plant were determined. Root, shoot, and total length were greater in seedlings grown in soil where nigrogen was applied than that grown in soil to which no nitrogen was applied. The average size of the seedlings as determined by volume and weight was more than two times greater where plants were fertilized with nitrogen. Nodule number per seedling was also greater when nitrogen was applied compared to those which received no nitrogen. The differences were greater as the plants became older. The rhizobia did not fix enough nitrogen for adequate growth of seedlings. This is probably due to high temperature growing conditions that caused the rhizobia to become relatively ineffective as compared to cooler growing conditions. Data suggests it would be desirable to apply nitrogen at seeding when alfalfa is established under hot conditions that occur in mid- or late summer.

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.2
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• pp.59-69
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• 2019

This study was carried out to investigate effects of soil water content on growth and antioxidative enzymes activity of tomato seedlings during the nursery period. The water stress significantly damages morphological, physiological, and biochemical activities in plants. The seedlings planted with soil on the tray were irrigated and categorized into 3 groups with 30 g, 40 g, and 50 g of plant-soil weight. After then, the changes in weight of the soil and the seedling were measured evey 2 hours for 4 days and the leaf temperature was measured with the thermal-camera at the same time. The antioxidant enzymes were measured to determine the level of stress using all of the seedling samples. The result showed that the decrease of soil weight in the day time was faster than that in the night time, but there was no significant difference in the weight loss of the seedlings and soil among the groups. However, the group with 50 g of wight showed the highest SOD and POD contents. This is considered that the continuously wet soil on the root zone of the seedlings caused more stress for the seedlings. Therefore, it is concluded that the excess moisture content causes stress to stimulate the secretion of antioxidant enzymes, and the effect of stress is required to be analyzed comprehensively using environmental data and also the physiological data that are collected over a longer period.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.257-262
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• 2021

The pinning method is the traditional method to produce strawberry transplants. But, cultivating the pinning transplant is a labor-intensive operation and needs a long labor period. The cutting method has been considered as an effective alternative to the pinning method, due to the relatively short labor period and works time. This study was conducted to investigate the labor period, work time, and growth between pinning and cutting methods for strawberry transplants. The 'Maehyang' strawberry was cultivated at each pinning and cutting strawberry greenhouses. The time for special works on pinning method (pinning work, elimination of mother plant, and division of daughter plant), and cutting method (cutting collection, pretreatment before storage, and cutting work) were measured. The pinning method needed 6 tasks (planting of mother plant, maintaining of mother plant, pinning work, maintaining of daughter plant, elimination of mother plant, and division of daughter plant) for 158 days, and cutting method needed 4 tasks (collection and storage of cutting, cutting work, misting, and maintaining of transplants) for 113 days to cultivate transplants for fruit. And pinning method needed more work time than the cutting method. There was no significant difference between the growth of pinning and cutting transplants. These results showed that the cutting method saved more labor period, work time than pinning during the nursery period without losing transplant quality.

• Korean journal of applied entomology
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• v.20 no.3 s.48
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• pp.135-145
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• 1981

Vegetables including Chinese cabbage and radish have been grown in alpine areas such as Muju, Namweon, Jinan and Jangsu during the shortage period of vegetables. The incidence of various diseases, environmental factors such as temperatures and rainfalls, and aphid populations as virus vector were observed at 10-day intervals from July to September in those areas. Disease incidence showed no significant difference among locations. Major diseases in Chin ese cabbage were bacterial soft rot, white spot, downy mildew, mosaic virus, Alternaria leaf spot and Fusarium seedling blight. Major diseases in radish were virus, white rust, black rot, root rot, leaf spot and Fusarium seedling blight. Disease incidence reached peak on Aug. 20 with $27\%$ infection in radish and with $20\%$ infection in Chinese cabbage during the growing season, and declined thereafter. Percentage of infection in each growth stage showed $25\%$ at root thickening stage and $26\%$ at the harvest time in radish; and the head formation stage, $24\%$ at the harvest time. The data indicate that disease incidence in radish increased rapidly at late growing stage and progressively increased in Chinese cabbage Seedling blight caused by Fusarium sp. and root rot caused by Aphanomyces sp. were also observed in those areas. Cool and wet weather appeared to be favorable for disease incidences during the rainy period of growing season although average temperature was about $25^{\circ}C$. Populations of aphids were lower in the alpine vegetable growing area than that of flat areas. Aphids as virus vectors from total aphids collected were $73.5\%$ or 289 virus vectors /993 total aphids in Namweon and $18.1\%$ or 31 virus vectors/171 total aphids in Muju. The most prerevalent species of aphids was Myzus persicae Sulz.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.200-205
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• 2016

This study was conducted in order to investigate the effects that the difference of planting time by a method of cultivation in the non-heated greenhouse and the open field with spring planting had on growth and yield. With regard to the tested variety of Momordica charantia, variety 'Dragon' (Japan Yae 農藝) was selected. And 3 treatments on March 20, April 5 and April 20 for the greenhouse cultivation and 3 treatments on April 20, May 5 and May 20 for the open-field cultivation 1 month later than those for the greenhouse cultivation were planted by the randomized complete block design, and 4 secondary vines were trained. In the results of examining 15-day average atmospheric temperature after planting according to the methods of greenhouse and open-field cultivation and planting time, it was shown that there was a tendency for atmospheric temperature inside the greenhouse to decrease as the planting time was moved up. In particular, the average atmospheric temperature was $16.7^{\circ}C$ when seedling was planted on April 20 in the open-field cultivation, which was approximately equal to $17.0^{\circ}C$ of the average atmospheric temperature when a seedling was planted on March 20 in the greenhouse cultivation. With regard to the date of first harvest by the method of cultivation, it was shown that there was a tendency for the date of first harvest to be earlier in the greenhouse cultivation than in the open-field cultivation, and the date of first harvest was moved up as a seedling was planted earlier for the planting period. The number and weight of harvested fruits per plant showed a tendency which was almost similar to that of total number of harvest days and number of harvests. Thus, the number of fruits was 189 and the weight of fruits was 31,649g in case of the greenhouse cultivation and planting on March 20, which were maximum. In case of planting on the latest planting date : May 20 in the open-field cultivation, the number of fruits was 77 and the weight of fruits was 12,502g, which were at a level of 40% of those of planting on March 20 in the greenhouse cultivation 2 months earlier. The total yield per 10a was 10,228kg in the greenhouse cultivation and was 2.2 times as heavy as 4,607kg in the open-field cultivation with regard to the method of cultivation. For the planting period in the greenhouse cultivation, it was 10,539kg and 10,517kg in planting on March 20 and April 5, which was higher by 9% than 9,629kg in planting on April 20. And in the open-field cultivation, it was 4,785kg in planting on April 20 and 4,872kg in planting on May 5, which was higher by 15~17% than 4,163kg in planting on May 20. Taking the above results into account, it is considered proper to plant Momordica charantia from March 20 to April 5 for the greenhouse cultivation and from April 20 to May 5 or thereabouts when a risk of late frost is gone for the open-field cultivation in southern area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.344-352
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• 2019

Drought stress caused by global climate change is a serious problem for rice cultivation. Increasingly frequent abnormal weather occurrences could include severe drought, which could cause water stress to rice during the seedling stage. This experiment was conducted to clarify the effects of drought during the seedling period on yield and quality of rice. Drought conditions were created in a rain shelter house facility. The drought treatment was conducted at 3, 10, and 20 days after transplanting. Soil water content was measured by a soil moisture sensor during the whole growth stage. In this study, we have chosen 3 rice cultivars which are widely cultivated in Korea: 'Haedamssal' (Early maturing), 'Samkwang' (Medium maturing), and 'Saenuri' (Mid-late maturing). The decrease in yield due to drought treatment was most severe 3 days after transplanting because of the decrease in the number of effective tillers. The decrease in grain quality due to drought treatment was also most severe 3 days after transplanting because of the increased protein content and hardness of the grains. The cultivar 'Haedamssal' was the most severely damaged by water stress, resulting in about a 30% yield loss. Drought conditions diminished the early vigorous growth period and days to heading in early-maturing cultivars. The results show that drought stress affects yield components immediately after transplanting, which is a decisive factor in reducing yield and grain quality. This study can be used as basic data to calculate damage compensation for drought damage on actual rice farms.

• Journal of Forest and Environmental Science
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• v.35 no.4
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• pp.223-231
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• 2019

Castanopsis indica (Sil Batna) is an ecologically valuable multipurpose indigenous tree species of Bangladesh. Considering its high value but poor natural regeneration due to seed dormancy, the authors conducted an experiment at the Institute of Forestry and Environmental Sciences Chittagong University (IFESCU) during 2012-2013 to find out effective pre-sowing treatments. Ten pre-sowing seed treatments were applied on mature, even-sized seeds namely-control; sandpaper rubbing; nail clipping; immersion in normal water (at room temperature: 24℃) for 24 hrs., 48 hrs. and 72 hrs.; immersion in hot water (80℃) for 1 minute; soaking in 10% dilute H₂SO₄; soaking in 10% HCl for 5 minutes; and sowing in propagator house. Seeds sown after sandpaper rubbing at the distal end revealed best performances by providing highest germination percent (66.7%), germination energy (30%), germination index (0.17), germination rate (0.0145), germination value (30%) and plant percent (66.7%) within shortest period (38 days). The treatment also produced most vigor seedlings with 20.9 cm shoot height, 15 node number, and largest leaves (11.1 cm×2.9 cm). Hence, it is recommended to adopt sandpaper rubbing method for maximum germination and quality seedlings.

• Korean Journal of Medicinal Crop Science
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• v.1 no.1
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• pp.49-57
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• 1993

Seedling of Aralia continentalis is more effective method rather than use of vegetative organ for mass propagation. However, lower germination rate is the main problem for seeding. In this study, we analyzed substances in aim to relate to germination process. The results indicated that longer period of stratification brought lower amount of phenolic compounds in the seeds and both promoting and inhibiting substances were at very low level or gradually disappeared.

• The Korean Journal of Malacology
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• v.21 no.1
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• pp.65-70
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• 2005

The purpose of this study is to determine the appropriate substrate for larval settlement and spat growth in the purple clam, Saxidomus purpuratus in laboratory culture. Larvae were reared with 3 different types of sediments (mud, sand, and mixed) for 46 days in settlement experiment, and settled spats were further grown in 3 types of sediments for 36 weeks in growth experiment. The density of settled spats in muddy sediments was more than 2 times higher than those in mixed or sandy sediments. But, the average size of settled spats in muddy sediments was smaller than those in mixed or sandy sediments. After 36 weeks of growth period, growth rate decreased as shell length increased. When shell length was less than 2 mm, growth rate in mixed sediments was significantly higher than that in sandy sediments. When shell length was more than 2 mm, there was no significant difference in growth rate among different substrates. Sediment type affected growth rate only when the spats were relatively small (less than 2 mm). Muddy sediments seems better for larval settlement, while mixed sediments is best for spat growth. We suggest the laboratory procedure for enhancing seedling production of S. purpuratus.

• The Plant Pathology Journal
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• v.24 no.1
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• pp.63-66
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• 2008

The fermentation broth (FB) of Streptomyces griseofuscus 200401 isolated from non-farming soil showed antagonistic activity against powdery mildew fungus both in melon leaf/seedling assay and in field trials. The FB of S. griseofuscus 200401 was tested at different concentrations. In primary test, the control value of 2-fold diluted FB of S. griseofuscus 200401, compared to control, reached to 82.8%. The protective activity recorded 80.5% in 2-fold dilution of FB. The effect was reduced to 28.9% in high dilution (100-fold) treatment. The curative effect was relatively lower than protective activity. In field test, the antifungal activities of S. griseofuscus 200401 remained low in blocks sprayed with 100-fold diluted FB and the control values were 15.2 and 15.9% in 2005 and 2006, respectively. However, the activities were as high as 65% and 67.3% in the blocks treated with 2-fold dilution of FB during the same period.