• Journal of Bio-Environment Control
• /
• v.20 no.4
• /
• pp.326-332
• /
• 2011

The growth and bolting characteristics of spring Chinese cabbage cultivars at two night-time temperature treatments such as $5^{\circ}C$ and $10^{\circ}C$ during seedling stage were investigated to establish a safe environmental management strategy for raising seedlings. The low night-time temperature treatments were applied at 5, 10, and 15 days after sawing and the treatment durations were 5, 10, and 15 days in each of treatment beginning. The growth of seedlings in all the tested cultivars were linearly reduced as the treatment duration was extended and no symptoms of bolting were found. The reduction rate in seedling growth of 'Chunkwang' reached to 59.3% at most by 15 days of $5^{\circ}C$ treatment when it be compared to that of control. However, no symptoms of bolting were shown in the treatments of two night-time temperatures until the harvest at 90 days after sawing, indicating that the vernalization effect by low night-time temperature could be mitigated by subsequent day-time optimal temperature management. This study showed that the major spring Chinese cabbage cultivars require more ultimate level of low night-time temperature treatment for the vernalization than this study. It is also supposed that the optimal day-time temperature management can reduce or delay the rate of bolting, even if the seedlings were exposed to short-term low temperature below $5^{\circ}C$ during night-time.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.21 no.1
• /
• pp.125-131
• /
• 1976

To study the effects of temperature, day length, and various plant growth regulator treatments on the tuber formation of Irish cobbler, this experiment was carried out with 2 combinations of day-length and temperature and 11 kinds of growth regulator, including GA, and their combinations. For the tuber formation, low temperature-short day condition played decisive role, and exceeded the effects of growth regulators. 4 times foliar application of 10 ppm GA resulted marked elongation of stolon but did not inhibit the tuber formation even under high temperature longday condition.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.24 no.1
• /
• pp.11-24
• /
• 1979

To characterize elastic and plastic chilling injury, rice seedlings grown at 28/$16^{\circ}C$ day/night temp. under 20K lux (13hrs.) in a phytotron were subjected to a 11/$6^{\circ}C$, 20K lux condition for 2, 4, 6 or 8 days at 1, 2, 3, 4 or 5th leaf-stage, respectively, followed by further growth under 28/$16^{\circ}C$condition till 30th day after seeding. Japonica variety Jinheung and Chulwon No.1 survived almost 100% without any significant , discoloration and death of leaves due to chilling even under the chilling of 8 days at all seedling ages tested. Tongil and Yushin, varieties from Indica x Japonica cross, showed increasing discoloration of leaves and death of plants with increase in chilling intensity. The longest chilling duration shown seedling death less than 5% was 4, 6, 1, 4, 8 days for Tongil, and 6, 6, 1, 2, 2, days for Yushin at 1, 2, 3, 5th leaf-stage, respectively. The degree of discoloration and death of leaves or suppression of height growth was not explicitly related to seedling death or the dry weight reduction. The degree of seedling death or dry weight reduction could differentiate chilling tolerance of varieties and seedling ages, but somewhat differently. Reduction in dry weight due to chilling occurred even without any visible injury or seedling death. These suggest that both the degree of seedling death and reduction in dry weight should be considered in the test of varieties for chilling tolerance. Combined evaluation of seedling death and dry weight reduction indicated the most susceptible seedling age to chilling injury to be 1 to 2nd leaf-stage for Jinheung, 2 to 3rd leaf-stage for Chulwon No.1, 3rd leaf- stage for Tongil and Yushin, respectively.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.20 no.2
• /
• pp.39-47
• /
• 2018

This study was carried out to investigate the applicability of alternating temperature control during night time in a nursery seedling production. Three groups of samples were exposed to three different environmental conditions for 6 days from 18:00 to 09:00; one was constantly 15 ℃, another was alternating between 15 ℃ for 2 hours and 11 ℃ for 2 hours, and the other was alternating between 15 ℃ for 2 hours and 11 ℃ for 4 hours. Leaf temperature and stem temperature was measured in real time. The influence of cold stress was analyzed by flavonoid content and growth of tomato seedling. The temperature of leaves and stem became equal to the ambient temperature over time, furthermore, there was no significant difference among the treatments. In conclusion, it is considered that heating costs can be saved considerably, as the alternating temperature has fewer effects on cold stress reaction by tomato seedling growth.

• Horticultural Science & Technology
• /
• v.28 no.5
• /
• pp.783-789
• /
• 2010

The effective method for heating root-zone during winter season was studied in the aspects of growth, yield and economics for tomato ($Solanum$ $lycopersicum$) in perlite bag culture. There were four root-zone heating treatments: two hours heating from one hour before to one hour after sunrise, four hours from two hours before to two hours after sunrise, 15 hours after sunset, and no heating. The growth characteristics of the upper parts of plants were not significantly different among the treatments, but root volume increased with longer heating of the root zone. The Plant Development Index, using stem diameter and the length between growing tip and the upper flowering truss, showed relation between yield per cluster and growth pattern. The treatment heating for four hours was the most economic in terms of growth and yield of tomato.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.21 no.1
• /
• pp.35-42
• /
• 1976

In Korea, two types of rice varieties are being cultivated widely, Japonica and Japonica-Indica cross. Generally speaking, the latter shows weak cold tolerance than the former and so brought about many problems in cultural practices. This study was conducted to investigate the effect . of various temperature conditions on rice seedlings growth, especially the contents of chlorophyll and the percentage of nitrogen. And the result obtained indicated the varieties of Japonica-Indica intend to weak cold tolerance than Japonica varieties.

• Journal of Bio-Environment Control
• /
• v.15 no.2
• /
• pp.149-155
• /
• 2006

This study was carried out to investigate effects of different night temperature treatments during nursery period on flower bud differentiation and growth of pepper cv. Cheongyang. Number of leaves, top fresh weight and top dry weight of pepper seedlings were increased with increasing the night temperature during nursery periods. And also flower bud differentiation and days to flowering were accelerated as increasing the night temperature. Plant height, stem diameter, branch length and intermode length of pepper after transplanting were height at the low night temperature ($28/11^{\circ}C$), but they were retarded at the high night temperature ($28/21^{\circ}C$) treatment. Number of lateral branches was significantly reduced at the high night temperature, but there was no a regular tendency in branching habit of the main stem by temperature treatments. Seedling growth before transplanting was retarded at the low night temperature but gradually recovered after transplanting into the plastic house. However, seedling growth at the high night temperature was shown in contrast to above response of the low night temperature.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.24 no.2
• /
• pp.17-26
• /
• 1979

Comparative tolerance of the new rice varieties from Indicax Japonica cross to elastic and plastic chilling injuries was examined at the 3rd leaf-stage, the most sensitive stage to chilling during nursery, using a chilling chamber set 11\circ C, 13hrs. 20K lux day/5$^{\circ}C$ night. Seedlings were reared until 35 days after seeding in a 26\circ C, 13hrs. day / 18\circ C night chamber except the period of chilling treatment for 0, 3, 4, 6, 8 or 10 days. The new varieties were approximately twice susceptible to elastic injuries, and thrice susceptible to plastic injuries than the Japonica varieties in the term of chilling duration. Among the variables indicating apparant chilling injuries the reduction in dry matter responded most sensitively and differentiated well the varietal difference in chilling resistance even with shorter chilling period. Sequential aspects of the cause and effect relations involved in the development of the apparant chilling injuries are discussed and a schematic diagram is presented as Fig. 5 in the text.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.21 no.2
• /
• pp.203-210
• /
• 1976

To abtain basic information in process developing cold tolerance rice variety, used 8 varieties which are the close crossing and the remote crossing in order to clarify how is being the differences of low temperature injury in same variety and the varietal difference at each growth stage under the low temperature treatment, 18$^{\circ}C$-12$^{\circ}C$ (day-night), and to establish the effective testing method for low temperature injury in rice plant. In this experiment, the varietal ifferences of low temperature injury were significant in rice plant, and found out that low temperature injury at the each growth stage from sowing to heading in same variety was not horizontal.

• Journal of Bio-Environment Control
• /
• v.15 no.4
• /
• pp.390-395
• /
• 2006

Effects of exogenously foliar applied glycine betaine (GB) on the growth and contents of osmolyte in tomato seedling was investigated. Plants treated with exogenous glycine betaine induced better biomass production and plant height during chilling stress than the untreated plants. The total soluble sugar contents in GB foliar-applied plants lower than that of untreated plants 28 days after foliar application. Total water soluble protein contents in GB foliar-applied plants did not change 28 days after chilling stress. In untreated plant, it decreased rapidly in the beginning of chilling stress. Proline contents in untreated plants rapidly increased by the beginning of chilling stress, and then slightly decreased during the next 3 weeks. However proline contents in GB foliar-applied plants did not change during the 28 days chilling stress period. The results suggest that foliar application of GB is a effect methods to increase the chilling tolerance of tomato seedlings in protected cultivation system at low temperature season.