• Research in Plant Disease
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• v.22 no.3
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• pp.202-207
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• 2016

Rice bacterial blight and blast are devastating rice diseases in worldwide. Riboflavin, vitamin B2, is an essential nutrient for human health, and is known to be as a growth regulator and as a plant defense activator against pathogens in plants. In this study, we investigated possibility of increasing internal vitamin B contents and inducing resistances against rice diseases by external foliar application of a riboflavin-based formulator called BioDoctor. In planta bioassay indicated that pretreatment of the foliar application of 1,000-fold or 500-fold diluted BioDoctor significantly induced disease resistance against rice blast and bacterial blight. In addition, about four fold higher levels of riboflavin contents were detected in the BioDoctor treated rice grain and stem compared to those of untreated rice. Our results indicated that foliar application of the riboflavin has a great potential to control plant diseases and to enhance internal vitamin contents in rice.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.263-270
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• 2021

This experiment was carried out to determine the effect of CaCl₂ foliar spraying on the inhibition of blossom-end rot (BER) in hot summer paprika (Capsicum annum L. 'Special') cultivation. The effect of CaCl₂ application was examined by the foliar application based on different fruit size, frequency, and spraying time. Also, it was investigated the occurrence and alleviation effect of BER symptom. Foliar application of CaCl₂ (Ca 0.4%) was conducted by treating a fruit and leaf at 4 to 9 nodes above the crown flowers of each plant with 350 mL per week from June 3 to July 1. When the CaCl₂ was sprayed at 7-day intervals for 4 weeks, the Ca content was the lowest in the fruit harvested with BER symptom in 11 to 20 mm of fruit width (FW). Four different regions in both BER symptom and normal fruits showed significant differences of Ca content, the highest was in pedicel, followed by stem-end, middle, and blossom-end. The Ca content increased sharply in normal paprika with 31-40 mm FW, in which Ca content was 78% higher than that of BER. Ca content in the middle and blossom-end of paprika over 21 mm in FW ranged 19.8% to 28.8% in normal fruits and 15.7% to 18.5% in BER, respectively. The incidence of BER increased rapidly by more than 60% in fruits with 31-40 mm FW. While there was no difference in fruit weight among the FW treatment, marketable yield rate was highest in the 21-30 mm FW, and the sugar content was high in the 11-30mm FW. When CaCl₂ was applied three times for 7 days to a paprika having a 21- 30 mm FW, the cell wall-bound (CWB) Ca content was the highest and the rate of BER was lowest with 6.3%. After 10 days of CaCl₂ foliar spray treatment, the CWB Ca content of paprika increased by 2.9 to 3.5 times compared to the control in all treatments. At 7 days after the CaCl₂ foliar spraying once a day at varying spraying time, the leaf burn observed from 9:30 a.m. to 17:00 p.m. and the proline content increased as the spraying time was delayed. Therefore, the CaCl₂ foliar spraying method for reducing of BER occurrence during paprika summer cultivation seems to be appropriate to spray 2-3 times at intervals of 3 days and before 8 a.m. at the time when the FW is 21-30 mm.

• Applied Biological Chemistry
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• v.24 no.1
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• pp.15-20
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• 1981

Changes of urease activity in plant leaves following foliar application of urea were investigated with soybean, rye, tomato, radish and cabbage which were actively growing in a field. In this experiment, the procedure of the enzyme assay included incubation of the reaction mixture at $60^{\circ}C$ for 3 hr in order to inactivate heat unstable enzmes which may utilize ammonia produced by urease. The leaves with urea application showed somewhat higher urease specific activities for 2-4 days immediately after the foliar spray as compared with controls. The most difference of the specific activies between urea treatment and control was usually observed 2 days after urea application regardless of the plants. The difference of the specific activities disappeared completely 4 or 5 days following urea treatment. Protein contents in the leaves of soybean and tomato were increased for about 5 days after urea treatment, while no significant difference was found with rye, radish and cabbage. Urea application showed slightly lower ammonia concentration in the leaves which had higher urease activities. These results suggest that foliar spray of urea is very effective when nitrogen supply is required for rapid growth.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.480-485
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• 2014

In satsuma mandarin (C. unshiu Marc. cv. Miyagawa), alternate bearing is frequently occurred. It is very difficult to control and maintain the optimum production because satsuma mandarin is a very sensitive citrus cultivar. We carried out the experiment to find out the effects of foliar application of gibberellic acid ($GA_3$) and machine oil emulsion mixture on flowering and fruit quality of satsuma mandarin grown on open field. The treatments were composed of control (no application), $GA_3$ (25, 50 and $100mg{\cdot}L^{-1}$), machine oil emulsion 100 times and mixture of $GA_3$ (25 and $50mg{\cdot}L^{-1}$) with machine oil emulsion 100 times on 16 year-old 'Miyagawa' satsuma mandarin on December 30, 2012. Foliar application of $GA_3$ during winter season led to a reduction of the flowering in the following year. $GA_3$ decreased flowering in dose dependant manner. However, application of $GA_3$ and machine oil emulsion (100 times-diluted mixture) inhibited effectively the flowering compared to $GA_3$ only. Also, flower-leaf ratio was significantly decreased by the application of $GA_3$ 25 (0.54) and $50(0.41)mg{\cdot}L^{-1}$ with machine oil emulsion mixture in comparison to $GA_3$ 25 (0.86) and $50(0.60)mg{\cdot}L^{-1}$ only. The number of leaves per fruit increased in application of $GA_3$ and machine oil emulsion mixture as concentration of $GA_3$ increased. Fruit weight and sugar-acid ratio also increased in comparison to the control whereas fruit size, soluble solid content and acidity remained unchanged. From the results, it was suggested that $GA_3$ application can reduce the number of flowers on the alternate bearing of satsuma mandarin. Moreover, application of $GA_3$ (25 and $50mg{\cdot}L^{-1}$) with machine oil emulsion 100 times mixture can reduce the flowering effectively without altering fruit maturity and soluble solid contents. Therefore, it can be concluded that the application of $GA_3$ 25 and $50mg{\cdot}L^{-1}$ with machine oil emulsion 100 times might be useful in controlling alternate bearing in satsuma mandarin.

• Horticultural Science & Technology
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• v.18 no.6
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• pp.792-796
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• 2000

The staking cultivation (SC) of oriental melon (Cucumis mela L. var. makuwa Mak.) produced more fruit yield than that of the conventional (creeping) growing. In the SC, preharvest fruit drop rate was high as 47.6% compared to 13.0% of the conventional cultivation. However, the foliar application of aminoethoxyvinylglycine (AVG, $100mg{\cdot}L^{-1}$) at 2 weeks after flowering (20 days before harvest) greatly reduced fruit drops up to 10.9% without causing any effects on ripening and quality of fruits . The AVG application markedly suppressed ethylene production in harvested fruits.

• The Plant Pathology Journal
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• v.35 no.5
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• pp.406-416
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• 2019

Strawberry, an important fruit crop, is susceptible to a large number of pathogens that reduce fruit quality and productivity. In this study, the effect of a biostimulant prepared from Ascophyllum nodosum extract (ANE) (0.1%, 0.2%, and 0.3%) was evaluated on powdery mildew progression under greenhouse and field conditions. In the greenhouse, application of 0.2% ANE showed maximum reduction in powdery mildew progression as compared to the control. Forty-eight hour post-inoculation, foliar spray of 0.2% ANE reduced spore germination by 75%. Strawberry leaves sprayed with ANE showed higher total phenolic and flavonoid content in response to powdery mildew infection. Furthermore, application of ANE elicited defense response in strawberry plants by induction of defense-related enzymes, such as phenylalanine ammonia lyase, polyphenol oxidase, and peroxidase activity. In field conditions, foliar spray of 0.2% ANE showed a reduction of 37.2% of natural incidence of powdery mildew infection as compared to the control. ANE sprayed plant also reduces the severity of powdery mildew infection under natural conditions. These results indicate that application of ANE induces the strawberry plant's active defense against powdery mildew infection by induction of secondary metabolism and regulating the activities of defense-related enzymes.

• Journal of Bio-Environment Control
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• v.12 no.1
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• pp.17-21
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• 2003

This experiment was conducted to find out the method of preventing decrease in the marketable yield of oriental melon (Cucumis melo L. var. makuwa MAKINO) under low light intensity. By maintaining low light of 400 $\mu$mol$.$m$^{[-10]}$ 2$.$S$^{-1}$ from 10 days after fruit set to fruit enlargement period, the photosynthetic rate and chlorophyll contents of leaf were reduced. Leaves which had no urea application showed largely decreased photosynthetic rate The content of soluble solids was lower$.$ in the low light than natural light treatment. Regardless of foliar application of urea, % fermentation fruits was under 4% in the natural light treatment and over 10% in the low light treatment. The less the fruit thinning, the greater was % fermentation fruits under low light condition. The % fermentation fruits were 39% and 40% in no fruit thinning treatment. The harvest was delayed under low light condition regardless of foliar fertilization. As the number of thinned fruits was decreased, the harvest time was delayed more. Marketable yield per plant sharply decreased under low light intensity. Compared with natural light, the yield under low light treatment was 16∼34%. The treatment fertilized with 0.5% urea on leaf had 34% greater harvest index of marketable yield than other treatments. In conclusion, when the long low light condition from 10th day after fruiting was forecasted, thinning two fruits out of six fruits and two times foliar fertilization with 0.5% urea should be applied.

• Journal of Bio-Environment Control
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• v.7 no.4
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• pp.276-282
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• 1998

This experiment was carried out to elucidate the effect of ethychlozate foliar application on the fruit quality of Miyagawa Early Satsuma Mandarin in the plastic house. Ethychlozate(100mg.L$^{-1}$ ) was applied to the fruit at 100, 115 and 145 days after full bloom stage. The fruit was divided into four frequency level groups, with the control group receiving no Ethychlozate treatment and the level 3 group receiving all three applications. Peel coloration by a value Increased as application frequency increased. The a/b value trend was seen to be similar to this, but the b value ran contrary to the a value trend. Glucose contents of the fruit juice did not differ statistically among the application frequency levels but the fructose level was seen to be higher with increasing application frequency. Sucrose showed a similar trend to fructose in that it had a tendency to increase as application frequency increased. As a result of this, total sugar increased naturally with application frequency. The average Brix level among all treatment groups was higher than the average Brix level in the control group but Brix level did not differ significantly among application frequency levels. Acidity had a tendency to increase as application frequency increase, but there was no statistical difference found.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.170-179
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• 2022

Glutamic acid is a precursor of essential amino acids that play an important role in plant growth and development. It is one of the biostimulants that reduce cold stress damage by stimulating biosynthetic pathways leading to cryoprotectants. This study evaluated the effects of glutamic acid foliar application on Kimchi cabbage under low-temperature stress. There were six treatments, combining three photo-/dark periods temperature levels (11/-1℃ extremely low, E; 16/4℃ moderately low, M; and 21/9℃ optimal, O) with and without glutamic acid foliar application (0 and 10 mg·L^-1; Glu 0 and Glu 10). Glutamic acid foliar application was sprayed once 10 days after transplanting, and then temperature treatment immediately after glutamic acid foliar application was conducted for up to four days. After four days of treatment, abscisic acid (ABA), phaseic acid (PA), dihydrophaseic acid (DPA), and abscisic acid-glucose ester (ABA-GE) contents were higher with Glu 10 treatment than Glu 0 treatment in M treatment. Glucose content was highest in E with Glu 10 treatment (52.1 mg·100 g^-1 dry weight), while fructose content was highest in O with Glu 0 treatment (134.6 mg·100 g^-1 dry weight). The contents of glucolepiddin (GLP), glucobrassicin (GBS), 4-methoxyglucobrassicin (4MGBS), neoglucobrassicin (GNBS), and gluconasturtiin (GNS) were highest among all treatments in E with Glu 10 treatments (0.72, 2.05, 1.67, 9.40 and 0.85 µmol·g^-1 dry weight). After two days of treatment, rapid changes in PA and DPA contents of E with Glu 10 treatments were confirmed, and several individual glucosinolate contents (GLP, GBS, 4MGBS, GNBS, and GNS) were significantly different depending on low temperature and glutamic acid treatment. In addition, the content of fructose was significantly lower than that of O treatment in E and M treatments after four days of treatment. Therefore, although the changes in PA, DPA, glucose, fructose, and individual glucosinolates according to low temperature and glutamic acid foliar treatment were shown. A clear correlation between low temperature and glutamic acid effects could not be evaluated. Results indicated that Brassica crops are cryophilic vegetables, do not react sensitively to low temperatures, and mostly have cold resistance.

• The Plant Pathology Journal
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• v.18 no.2
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• pp.93-97
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• 2002

Aster yellows phytoplasma-infected chrysanthemums showing stunt, rosette, and excessive branching were treated with a foliar spray of 400 mg/I oxytetracycline at three-day interval for 1,2,3 and 4 months. Two months after the final treatment, new shoots from the recovered chrysanthemums showed the recurrence of the disease symptoms. However, cuttings from chrysanthemums treated with oxytetracycline did not express any photoplasma infection symptoms for more than 10 months. Also, chrysanthemums dipped in 100 mg/I oxytetracycline solution combined with a foliar spray of 400 mg/I oxytetracycline for 4 weeks showed the same results. Using an electron microscope, ultrathin sections of leaf midribs of chrysanthemum cuttings treated with oxytetracycline for 4 months did not show phytoplasma bodies 10 months after treatment. Nucleic acids from chrysanthemums, which did not express phytoplasma infection symptoms for more than 10 months, did not amplify 16S rRNA gene of phytoplasma by polymerase chain reaction. These results may have implications in the propagation of phytoplasma-free healthy stocks for a wide range of plant species.