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Background and objective: This study was conducted to find out the effects of Saemangeum reclaimed landscape colors on perceived restorativeness and revisit intention.Methods: A survey was conducted on 120 general respondents, and the responses from 112 respondents were analyzed, except 8 inappropriate responses. The average age of all respondents was 48.60 ± 12.99.Results: Regarding psychological indicators for Saemangeum reclaimed landscape images, this study analyzed the demographic variables of the visitors by four factors of the Perceived Restorativeness Scale (PRS). The result showed that there were statistical significance in age, education, average monthly income, and occupation. The correlation analysis showed that there was a positive correlation between satisfaction and preference in the Saemangeum reclaimed landscape, four factors of PRS, and loyalty showed positive correlations and had statistical significance. As for the preference in Saemangeum reclaimed landscape colors, purple was the most preferred among the eight colors. For the question about satisfaction and loyalty to the Saemangeum reclaimed landscape, more than 87% of respondents responded 'Agree' and 'Strongly agree.' Moreover, a regression analysis including dummy variables was conducted to identify the influence of satisfaction, preference, PRS, and demographic variables (control variables) of visitors. The results showed that preference and fascination among the four factors of PRS had a positive effect on loyalty to the Saemangeum reclaimed landscape. In contrast, the age 20 - 29 (β = -.29, p < .05) had a significant negative effect on loyalty. In other words, higher attention restoration due to preference and 'fascination' and age older than 29 resulted in higher loyalty to the Saemangeum reclaimed landscape. Meanwhile, gender, education, and occupation did not affect the preference.Conclusion: In conclusion, this study identified that the Saemangeum reclaimed landscape affects positive emotions such as 'fascination' and landscape preferences of visitors, and thus would be useful for increasing the revisit intention of visitors.

Background and objective: This study investigated the preferences and repurchase intentions (loyalty) of respondents to 8 coleus (Coleus scutellarioides) cultivars potentially useful for tropical style streetscapes.Methods: A survey was conducted on 148 general respondents, and the responses from 136 respondents were analyzed excluding 12 inappropriate copies.Results: Through demographic analysis on plant gardening experience, plant preference tendency, and plant-related event, we discovered that plant preference tendency was lowest in the 20s and highest in the 60s and above, indicating that plant preference tendency significantly increased with age. Out of 6 factors on perceived importance of plants, environmental and emotional relaxation for improved quality of life were high. As a result of examining the emotional responses felt by looking at the images of 8 coleus cultivars, there was a statistically significant difference among cultivars. Major emotional words were 'calm' and 'comfortable'. There was a positive correlation between loyalty to coleus, preference, Korean version of WHOQOL-BREF, plant gardening activity level, and the importance of plants, and a negative correlation with PSS-K (Korean Perceived Stress Scale). We conducted a multiple regression analysis including dummy variables to examine the effect of plant gardening activity level, PSS-K, and Korean version of WHOQOL-BREF on loyalty of survey respondents. The results showed that the effect was greatest in the order of plant-related event, physical health domain, age (50's), covers, environment domain, male, and age (30's).Conclusion: Our results demonstrated that coleus could mitigate the psychological stress and depression. As 'Lime Delight' with simple green color showed the highest preference among cultivars, we recommend a green cultivar from the psychological point of view rather than combination planting of multi-colored cultivars.

Background and objective This study was conducted to establish a Plant Hardiness Zone (PHZ) map, investigate the effect of global warming on changes in PHZ, and elucidate the difference in the distribution of evergreen trees between the central and southern region within hardiness Zone 7b in Korea. Methods Mean annual extreme minimum temperature (EMT) and related temperature fluctuation data for 40 years (1981 to 2020) in each of the meteorological observation points were extracted from the Open MET Data Portal of the Korea Meteorological Administration. Using EMT data from 60 meteorological observation points, PHZs were classified according to temperature range in the USDA Plant Hardiness Zone Map. Changes in PHZs for each decade related to the effects of global warming were analyzed. Temperature fluctuation before and after the day of EMT were analyzed for 4 areas of Seoul, Suwon, Suncheon, and Jinju falling under Zone 7b. For statistical analysis, descriptive statistics and ANOVA were performed using the IBM SPSS 22 Statistics software package. Results Plant hardiness zones in Korea ranged from 6a to 9b. Over four decades, changes to warmer PHZ occurred in 10 areas, especially in colder ones. Based on the analysis of daily temperature fluctuation, the duration of sub-zero temperatures was at least 2 days in Seoul and Suwon, while daily maximum temperatures were above zero in Suncheon and Jinju before and after EMT day. Conclusion It was found that the duration of sub-zero temperatures in a given area is an important factor affecting the distribution of evergreen trees in PHZ 7b.

Calla lily cultivar ‘Swan’ was bred by the National Institute of Horticultural and Herbal Science (NIHHS) in 2017. ‘Swan’ was a cross between multi-flowering cultivar ‘Childsiana’ and soft rot-resistant cultivar ‘Wedding March’ in 2004. Its multiplication, bulb enlargement, and growth and flowering characteristics were evaluated from 2008 to 2016. It was selected from the 3rd characteristics tested and renamed as the new cultivar ‘Swan’ by the New Variety Deliberation Committee of Rural Development Administration in 2017. The growth and flowering characteristics of ‘Swan’ and ‘Wedding March’ were compared. ‘Swan’ has white (RSH155C), medium-sized flowers, with a flower width of 10.3 cm and flower diameter of 11.2 cm. The average number of flowers per plant was 2.2, which was twice as many as that of the control cultivar, and the length of the flower s talk w as 77.1 cm longer t han that o f the control cultivar (68.7 cm). ‘Swan’ is an early-flowering cultivar with 65 days of flowering. The life of cut flowers was 17 days, and they were moderately resistant to soft rot. ‘Swan’ was registered in 2020, and its grant number in Korea is 8092.

Salt stress is a major constraint of crop productivity because it reduces yield and limits the expansion of agriculture. This study investigated salt tolerance in 26 cultivars of cut lilies (Lilium hybrids) by examining the effect of salt stress on the growth and morphological characteristics of flowers and leaves and their physiological properties (chlorophyll a fluorescence). Salt stress significantly affected the growth and development of cut lilies. Canonical discriminant analysis indicates that the middle leaf width, number of flowers, first flower diameter, petal width, and chlorophyll a fluorescence were correlated with salt stress, whereas plant height, the middle leaf length, days to flowering, and sepal width were less affected by the stress. The cultivars examined were divided into three groups: Group 1 included the salt-sensitive cultivars, which failed to develop normal flowers, Group 2 included cultivars sensitive to salt stress but tolerant to osmotic stress, and Group 3 was the salt-tolerant group, which developed commercially valuable flowers. In conclusion, the cultivars contained a variable range of cut flower characteristics and growth traits that can be employed for lily breeding programs and as material for molecular mechanisms and signaling networks under salt stress.

Scent is one of the most important economic traits in Freesia hybrida. “Shiny Gold”, a popular cultivar in South Korea, is widely cultivated for its scent. The relative scent intensity of “Shiny Gold” was approximately 16% higher in full-bloomed flower when compared to the yellow bud stage, while tissue-specifically, tepals showed higher intensity in electronic-nose (e-nose) analysis. E-nose analysis also showed that the scent intensity of “Shiny Gold” was higher and lower than “10C3-424” and “10C3-894”, respectively, and was similar to “Yvonne”. These results correlated to those of the olfactory tests. In total, 19 volatile compounds, including linalool, β-ocimene, D-limonene, trans-β-ionone were detected in gas chromatography–mass spectrometry analysis. Among these, linalool was the major volatile compound, accounting for 38.7% in “Shiny Gold”. Linalool synthase and TPS gene expression corresponded to the scent intensity of the four cultivars, with the lowest expression in the “10C3-424”. TPS 2, TPS 3, TPS 5, TPS 6 and TPS 8 were highly expressed in both bud and flower in “Shiny Gold”, while the expression of TPS 4 was lower, relative to other TPS genes in both the flowering stages. These results may aid in enhancing scent composition in Freesia cultivars using marker-assisted selection.

Freesia (Freesia hybrida Hort.) ‘Sweet Lemon’ was developed for the cut flowers in National Institute of Horticultural Herbal Science, Rural Development Administration, Korea in 2015. This hybrid was crossed and selected from ‘Teresa’ and ‘Yvonne’ in 2007. Morphological characteristics of the selected freesia hybrid were investigated for 5 years from 2009 to 2014, and then it was named ‘Sweet Lemon’ in 2015. ‘Sweet Lemon’ has double and lemon petals (RHS color chart Y2B). The average flower diameter was 6.8 cm and the average yield is 6.7. The growth of the plant is vigorous and the average plant height is 99.0cm, which is 34.7cm higher than the standard cultivar ‘Yvonne’. The average floret number per stalk of ‘Sweet Lemon’ was 10.7, and stalk length was 7.7 cm. The average days to first flowering of ‘Sweet Lemon’, 126 days, was approximately 20 days earlier than the control cultivar. It’s average vase life and yield is 8.7 days and 5.6 cormlets per plant, respectively. Totally 58 of volatile compounds were identified using gas chromatography-mass spectrometry (GC-MS), the major components were linalool, alpha-terpineol, alpha-selinene, and limonene.

Ranunculus asiaticus characterizes colorful and attractive flower shapes that are related with the ornamental value of bulbous plants. Improving ornamental value of bulbous flowers has been the general goal of floricultural market. Gibberellic acid (GA3) and benzyladenine (BA) play an important role in growth and developmental processes in floriculture. Combinational treatments of these two hormones have been used in floriculture to improve flower quality. We assessed the effects of combined GA3 and BA, as well as the individual effects of each hormone, on growth characteristics using soil drench application to eight R. asiaticus cultivars, ‘Giallo Millepetali’, ‘Bianco Millepetali’, ‘Arancio Millepetali’, ‘Rosa SC’, ‘Arancio Pratolino’, ‘Giallo Pratolino’, ‘Bianco Pratolino’, and ‘Rosa Ch Pratolino’. GA3 treatments increased plant height and first flower size of R. asiaticus cultivars. Moreover, about 5 to 9 days to flowering were averagely shortened by GA3 treatments compared to controls. On the other hand, the opposites, including first flower size and days to flowering, were observed for cultivars treated with BA, compared with controls. Treatments of GA3 + BA generally affected growth traits, such as plant height, flower size, and the timing of flowering on some R. asiaticus cultivars. In particular, about 5 to 6 days to flowering were reduced on average by Treatments of GA3 + BA. Our results showed positive growth effects, including plant height, days to flowering, first flower height, number of flowers from the application of individual and combined hormones to R. asiaticus cultivars and demonstrate a role for these hormones in future bulbous floriculture.

In Lilium, a popular horticulture crop, the main objective of crossbreeding is introgression of desirable genes and features into new cultivars. Commercial Lilium cultivars were produced primarily through 2n-gametes or 2x-gametes as parental plants or backcrossing. The primary genetic difference in 2 methods, is the presence of genomic recombination. Especially, GISH (genomic in situ hybridization) among molecular cytogenetic analysis, is the relevant technique to detect genetic information; genome composition, chromosome behavior during meiosis and recombination of hybrids as using their parental DNA as a probe. Based on previous studies, in this research, 12 LA (L. longiflorum x L. Asiatic hybrids) hybrids were analyzed by GISH (genomic in situ hybridization) along with ploidy analysis, and pollen germination tests. The LA hybrids used in this study, showed less pollen germination ability (ranged 0 - 21.74%), but germination of ‘Caesars Palace’ was significantly higher (59.09%). Interestingly, ploidy analysis showed that ‘Caesars Palace’ was tetraploid and ‘Batistero’ had one more additional chromosome from the L genome. Nine of the 12 cultivars exhibited recombination and 3 had only non-recombinant chromosomes; fewer L. longiflorum chromosomes were present in the cultivars than Asiatic chromosomes. Consequentially, it is assumed that 2n-gametes were more common methodology than 2x-gametes for producing commercial cultivars. Moreover, backcrossing tended to be performed with the Asiatic hybrid cultivar.

Analyzing chromosomal traits is one of the pragmatic ways to establish evolutionary and genetic database of plants that has complicated phylogenetic system. There are some conflicts on the exact phylogeny and evolutionary pathway of Lilium, and section martagon is the most complicated part among them. In this study, chromosomal traits of martagon lily species are described. All martagon lilies were analyzed with FISH (Fluorescence in situ hybridization) technique, followed by detailed karyotyping. Each species showed 2n = 2x = 24 of chromosome complement. Size of chromosomes ranged from 451.04 to 680.06 µm. 5S and 45S ribosomal DNA, general molecular markers in modern evolutionary research were used as probe in this study. Variation in rDNA loci and chromosome translocation were observed in Lilium hansonii; the highest number of 45S rDNA loci was detected in Lilium hansonii, followed by other martagon lilies, in similar locations but with differences, and chromosome translocation was observed from one individual of Lilium hansonii. Additionally, Lilium tsingtauense from Jeju-do Island, Korea was detected with two extra chromosomes. These kind of genetic variations through karyotyping indicate ongoing genetic variations in martagon lilies. In this study, precise analysis of chromosome traits in Lilium species belonging to section martagonperformed to contribute to better comprehension of the evolutionary pathway and establishment of cytogenetic database for further plant breeding research.

Scent is one of the most important economic traits in Freesia hybrida. &ldquo, Shiny Gold&rdquo, a popular cultivar in South Korea, is widely cultivated for its scent. The relative scent intensity of &ldquo, was approximately 16% higher in full-bloomed flower when compared to the yellow bud stage, while tissue-specifically, tepals showed higher intensity in electronic-nose (e-nose) analysis. E-nose analysis also showed that the scent intensity of &ldquo, was higher and lower than &ldquo, 10C3-424&rdquo, and &ldquo, 10C3-894&rdquo, respectively, and was similar to &ldquo, Yvonne&rdquo, These results correlated to those of the olfactory tests. In total, 19 volatile compounds, including linalool, &beta, ocimene, D-limonene, trans-&beta, ionone were detected in gas chromatography&ndash, mass spectrometry analysis. Among these, linalool was the major volatile compound, accounting for 38.7% in &ldquo, Linalool synthase and TPS gene expression corresponded to the scent intensity of the four cultivars, with the lowest expression in the &ldquo, TPS 2, TPS 3, TPS 5, TPS 6 and TPS 8 were highly expressed in both bud and flower in &ldquo, while the expression of TPS 4 was lower, relative to other TPS genes in both the flowering stages. These results may aid in enhancing scent composition in Freesia cultivars using marker-assisted selection.

Lilium lancifolium (syn. L. tigrinum) is the only polyploidy-complex species involving both diploid (2n = 2x = 24) and triploid (2n = 3x = 36) plants in the genus. The origin of natural triploid remains a mystery and research has been limited mainly to chromosomal studies that have overlooked research on pollen ontogeny. By spatiotemporal comparison of the development and morphology of diploid and triploid pollen grains, we study the correlations between pollen fertility and morphological development in diploid and triploid plants and propose the necessity and importance of further research on natural polyploid-ontogenetic diversity. In this comparative investigation, we used various microscopy techniques including histological analyses, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The main morphological differences between triploid and diploid pollen grains started with abnormal tetrad formation of triploid, followed by inadequate amylogenesis and amylolysis in young microspores, and finished with the formation of an abnormal structure of pollen surface layers in maturing pollen grains, which finally resulted in pollen grain unfolding and male sterility. From observing the series of morphological events that induced male-sterile pathway in natural triploid pollens, this study showed a variety of correlations between pollen development and fertility, which differed from male sterility resulting from gene mutation, indicating that there exists greater variability in pollen male-sterile ontogeny. Our results suggest that multilateral research is required for understanding the fickle ontogeny of natural male-sterile polyploid.

This study was conducted to investigate the effects of pretreatment and shipping temperature on leaf chlorosis in cut Lilium Oriental hybrid ‘Siberia’. Cut lilies were shipped under various temperatures (5, 10, 15, 25℃) for 5 days. When cut lilies were shipped at 25℃, leaf chlorosis was accelerated. However, chlorosis was significantly decreased by shipping at 5 to 15℃. In addition, leaf chlorosis was significantly decreased when the cut lilies were pretreated with a solution containing Promalin (BA + GA 4+7 ) as compared to the control. Promalin completely prevented postharvest leaf chlorosis, whereas GA₃3 and Chrysal SVB were ineffective. Leaf chlorosis decreased more with Promalin dip treatment than with spray treatment. This pretreatment solution also extended the vase life of cut lilies. When cut lilies were pretreated with Promalin, yield (Fv/Fm) of chlorophyll fluorescence was highly maintained. Especially chlorophyll content was significant increased by Promalin treatment. Thus, shipping between 5 and 15℃ and Promalin dip pretreatment significantly decreased leaf chlorosis in cut ‘Siberia’ lilies.

A freesia (Freesia hybrida Hort.) ‘Shiny Bell’ was developed for the cut flower in the National Institute of Horticultural Herbal Science in 2012. This hybrid was selected from a crossing between cn. ‘Teresa’ and ‘Rossini’, which is white semi-double flowering and red double flowering, respectively. in 2004. Morphological characteristics of the selected hybrid were investigated for 3 years from 2009 to 2011, and then it was named ‘Shiny Bell’. ‘Shiny Bell’ had red color of RHS W155C, and double flower. The growth of the plant was vigorous and the average height was 109.3 cm. The average flower width was 5.8 mm, number of floret per stalk was 11.3, and stalk length was 8.5 cm. The average yield, 7.3 Branches per plant, was 3 stems per plant more than the control cultivar. The average days to first flowering of ‘Shiny Bell’, was 143.3 days, and it was approximately 7 days later than the control cultivar. The average yield of ‘Shiny Bell’ was 4.0 cormlets per plant.

Lily is an important cut-flower in Korea and world as well due to it’s a variety of flower colors and various sizes of flowers. To develop elite lily cultivars, conventional breeding techniques have been used so far. However, an introduction of tissue culture system in mass propagation of bulbs and regeneration of shoots with a high efficiency is prerequisite at this moment.Especially, growth of bulbs and shoots as well as reduction of browning is critical factor to proliferate bulbs with shoots of superior lines or cultivar in lily.For this purpose, we tried to test whether ascorbic acid, citric acid and silver nitrate in medium to facilitate growth of bulbs and shoots as well as reduction of browning of bulb scales in lily. As a result, ascorbic acid and silver nitrate showed no significant differences compared to control plants in the growth of bulbs and shoots. When bulb scales were treated with 150 mg ․l -1 of citric acid, formations of shoots and bulbs showed best result. While, bulb scale treated with 100 mg ․l

This study investigated trends in lily (Lilium hybrids) cultivars and challenges for growing cut lily flowers using a survey of producers in the South Korean lily industry. A questionnaire requested information on various topics including the total growing area, length of farming experience, cultivars grown, factors considered when purchasing bulbs, cultivation systems, horticultural practices, disease and pest problems, and horticultural problems. The survey targeted the membership of the Korea Lily Producer Association and the number of respondents corresponded to 43% of all lily farmers in the country. Oriental-Trumpet (OT) hybrid ‘Yelloween’ and Oriental hybrids ‘Siberia’, ‘Medusa’, and ‘Sorbonne’ were mainly cultivated in South Korea. The main flower colors were yellow, white, and pink. Factors considered in choosing cultivars were the prices of bulbs and cut flowers affecting income of the farm. More than 90% of respondents used soil culture in a greenhouse to grow cut flowers. There were various horticultural practices used from planting to harvest. The main pests harming bulb and flower productivity were fungus gnat (Bradysia difformis) and bulb mite (Rhizoglyphus robini), and the most common horticultural problem was leaf scorch. Overall, the survey suggested that the stable production of lily bulb with low cost and high quality was required and practical techniques should be developed for increasing the cut lily production efficiency. In addition, the pests, diseases, and horticultural problems in the given local environmental conditions should be considered when breeding new cultivars and developing production technology.

This experiment was carried out to establish the screening methods for the selection of Zantedeschia aethiopica cultivars resistant to calla lily soft rot caused by Pectobacterium carotovorum subsp. carotovorum. A center of leaf and petiole tissues of four Z. aethiopica cultivars were wounded and inoculated with three different inoculum concentrations, , , and , of EccNHRI-21 isolate. And they were evaluated at 4, 18, and 26 hours after inoculation. The lesion of maceration was developed well in the leaf tissues inoculated with concentration. And evaluation of resistance in 18 hours after inoculation was correlated with field resistance positively. Using this method, ten Z. aethiopica commercial cultivars and four wild types were screened. 'Crowbrough' and 'White Cutie' were selected as highly resistant genotypes and 'Mont Blanc' and 'Silky White' as resistant genotypes. 'Wedding March' and 'Kiwi Blush' were evaluated as moderate resistant and the others including 'Childsiana' were susceptible. And all of four wild types were evaluated as more than moderate resistant. In spite of control through cultural, biological and chemical methods, the use of resistant cultivars is most efficient to overcome calla lily soft rot. This newly developed screening method was helpful for breeding new varieties resistant to calla lily soft rot.

The effects of nutrient concentration and pH, two major chemical properties of soil, on plant responses were investigated with seedlings of tomato, which is widely grown in greenhouses, as the model plant. An experiment with four levels of nutrient concentration [None (NC 0), 1 (NC 1), 5 (NC 5), and 10 folds (NC 10)], in combination with three pH levels (4, 6, and 8), was conducted. The fresh and dry weight and leaf area of tomato seedling increased until NC5, but decreased at NC10. Transpiration rates, stomatal conductance, and evapotranspiration reduced with increasing nutrient concentration. The responses to the pH levels differed by the nutrient-concentration levels. The unsuitable root zone pH, pH 4 and pH 8, caused more reductions of transpiration rates, stomatal conductance, and evapotranspiration than pH 6 does under high nutrient concentrations, specifically pH 8 strongly depressed these. At pH 8, fresh and dry weight and areas of shoot and root sharply reduced more than at pH 4. Total nitrogen (...

This study was conducted to determine effects of soil pH and form of nitrogen fertilizers on tomato growth and chemical properties of greenhouse soil using ferigation system. Tomato (Lycopersicon esculentum Mill. cv. Superdoterang) were grown for three months in 18 L pots filled with two soil (pH 6.8 and pH 8.7). 4 different nitrogen fertilizers (urea, ammonium nitrate, ammonium sulfate, and potassium nitrate) were fertigated with different concentrations of 0, 10, 50, and 100 mg N/L during tomato cultivation. Soil pH 8.7 decreased yield and chlorophyll fluorescence compared with soil pH 6.8. Yield at soil pH 8.7 increased by ammonium nitrate and ammonium sulfate fertigation. Soil pH 6.8 induced increment of yield by nitrogen concentration than form of nitrogen fertilizers. Soil pH after cultivation of tomato decreased by application of ammonium nitrate and ammonium sulfate. Soil EC by 100 mg N/L application of ammonium sulfate was twice as much as other fertilizers. Form of nitrogen fertilizer had less effect on concentration of soil -N and -N in soil but the concentrations slightly reduced at pH 8.7. These results indicate that application of urea and ammonium nitrate for a nitrogen source of fertigation has little affects on soil chemical properties before and after tomato cultivation.

Various cultural practices have been promoted as management options for enhancing soil quality and health. The use of soil management methods can cause changes in fertility by affecting soil chemical properties. This study aimed to evaluate interactions between soil chemical properties and soil management methods in protected cultivation, and to classify soil management methods that similarly affect soil chemical properties. Water-logging and irrigation reduced soil pH and available P2O5 content. Application of animal manures has a positive effect on levels of organic matter, Av.P2O5, K, Zn, and Cu. The electrical conductivites tened to be low in the application of organic amendments, including rice and wood residues. Deeper plowing caused a reduction in Ca content. Practicing soil nutrient-considering fertilization and fertigation did not exert an influence on nutrient element contents. In a cluster analysis of the soil management methods according to major nutrients, low similarities were found with deeper plowing and crop rotation with rice in comparison with other practices. In a cluster analysis by minor nutrient characteristics, crop rotation and application of animal manures and rice residues were linked at a high Ward`s distance, while other practices were found to be relatively low distinct. Each soil management method has a similar or different effect on soil chemical properties. These results suggest the necessity of establishing limits and standards according to the effects of soil management methods on soil chemical properties for economic soil practices.

The thermotolerance and activation of antioxidant enzymes in the leaves of cucumber and tomato seedlings were induced by foliar application of H2O2. The induction of thermotolerance by foliar application of H2O2 was detected with decreased electrolyte leakage and malondialdehyde (MDA) content and increased water-soluble protein and chlorophyll content compared with heat-stressed seedlings. The levels of H2O2 and superoxide anions in the leaves of heat-stressed seedlings were also reduced by H2O2 pre-application before exposure to heat stress. The specific activities of ascorbic peroxidase (APX) and glucose-6-phosphate dehydrogenase (G6PDH) in the leaves of cucumber and tomato seedlings were significantly increased by foliar application of H2O2. The gel activities of superoxide dismutase (SOD), hydrogen peroxidase (HPX), and polyphenol oxidase (PPO) isozymes were abruptly increased by foliar application of H2O2 and these were maintained for 10 d afterward. The gel activities of guaiacol peroxidase (GPX) in the leaves of cucumber seedlings were significantly increased by foliar application of H2O2, but this did not occur in tomato leaves. Although one or two isoforms of SOD, HPX, and PPO isozymes in tomato leaves were suppressed by foliar application of H2O2, the total gel activities of the antioxidant enzymes were increased. These results suggest that foliar application of H2O2 before a crop is subjected to heat stress may be an effective and method to alleviate heat stress.