• Journal of Ecology and Environment
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• v.31 no.3
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• pp.193-200
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• 2008

We obtained quantitative information on leaf unfolding and leaf shedding by observing 45 species of cool temperate deciduous trees in an arboretum over 5 growing seasons. These trees were in leaf (the foliage period) for 207 days on average after 1 April; 50% of leaves had been shed by 192 days after 1 April. Duration from the start of leaf unfolding to 50% leaf shedding was 157 days on average. Leaf unfolding began 35 days on average after 1 April. For leaf unfolding to begin, a$ 51^{\circ}C{\cdot}day$ of cumulated daily mean air temperature above $5^{\circ}C$ from 1 January (modified Kira's warmth index) was needed. Fifty-nine days elapsed between initiation and the final stage of leaf unfolding. The period of net photosynthetic assimilation was 157 days. The species with succeeding- type leaf unfolding associated with the anemochore seed type dominated the early stage of succession, while the species with flush-type leaf unfolding tended to dominate the late stage of succession. Few species were found in regions where late frosts occur after the day when the cumulative temperature for leaf unfolding is achieved. Biological characteristics include time of leaf unfolding, which affects the life history of each species, so that each species occupies its own niche in the stand. We conclude that that leaf phenology, such as timing of leaf unfolding and leaf shedding, is one of the components of each species' ecological characteristics.

• Journal of agriculture & life science
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• v.45 no.1
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• pp.49-58
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• 2011

Characteristics of leaf unfolding and flowering of 31 chestnut varieties cultivated in southern Korea was conducted to provide basic data for chestnut varieties improvement. There were slight differences among varieties in leaf unfolding time and leaf unfolding was late in 2010 compared to 2008 and 2009. Leaf unlolding took about 8 days to complete in 2008 and 2009, but that took about two weeks to complete in 2010. In 2008 and 2009, flowering beginning and flowering end of staminate flower occurred in early May and June, those were detained by low temperature of April in 2010. Although pistallte flower in flowering characteristics showed very similar to flowering period of staminate flower, The flowering beginning for pistillate flower was earlier approximately 20 days than for staminate flower.

• Journal of Ecology and Environment
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• v.33 no.2
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• pp.121-131
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• 2010

Betula platyphylla var. japonica and Betula ermanii segregate vertically at an elevation of approximately 1,850 m on Mt. Neko in Nagano Prefecture, Japan. B. platyphylla var. japonica and B. ermanii were the dominant species below and above this altitude, at which the mean-annual and growing-season air temperatures were $4^{\circ}C$ and $14.1^{\circ}C$, respectively. Based on a modification of Kira's warmth index which employs cumulative temperature represented as $^{\circ}C$ day, leaf unfolding in both species was observed to be initiated at $58^{\circ}C$ day and $169^{\circ}C$ day, respectively. In 1996, leaf unfolding was initiated on 18 May in B. platyphylla var. japonica (+/-6 days) and on 5 June in B. ermanii (+/-8 days), shortly after the last frost which occurred on 5 May 1995 above 1,850 m; below this elevation there was no risk of frost at the time. At elevations above 1,850 m, the unfolded leaves of B. platyphylla were damaged by late frost, while B. ermanii escaped injury because the leaves were still protected by winter buds. The optimum temperature for seed germination in both B. platyphylla and B. ermanii was $30^{\circ}C$. Temperature alternation from 10 to $30^{\circ}C$ and moist storage of seeds at $4^{\circ}C$ (stratification) prior to incubation increased germination rates in both species. The seedlings of B. ermanii had a greater survival rates than those of B. platyphylla var. japonica when planted above 1,850 m. Comparisons of the timing of leaf unfolding and the latest frost at a site appeared to be the main factors affecting the vertical distribution of these species.

• Korean Journal of Plant Resources
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• v.33 no.2
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• pp.106-115
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• 2020

In order to find out the relationship between spring phytophenological index and temperature index for the past nine years (2010~2018), this study identified the relationship between temperature changes and trends in spring phytophenological index of sprouting, flowering and leaf unfolding of Pinus densiflora Siebold & Zucc., Larix kaempferi (Lamb.) Carrière, Quercus mongolica Fisch. ex Ledeb., Rhododendron mucronulatum Turcz., Lindera obtusiloba Blume and Acer pseudosieboldianum (Pax) Kom. in Daegu Arboretum, Palgong mt., Juwang mt. and Gaya mt. The change in temperature was caused by an increase in the monthly average temperature between March and April compared to February for nine years, and the average temperature of Daegu Arboretum and Palgong mt. were higher by region. The sprouting, flowering and leaf unfolding were the fastest of the Lindera obtusiloba and the slowest of the Pinus densiflora for each species, and the fastest plant season in Daegu arboretum came. SPI (Spring Phytophenological Index) tends to advance by -1.267~-6.151/9 years, with the largest Pinus densiflora (-6.151/9 years), with the lowest rate of change for Rhododendron mucronulatum (-1.267 days/9 years). Species which shows significant values in sprouting, flowering and leaf unfolding is Rhododendron mucronulatum and Pinus densiflora, which correlate with the mean temperature of January to March. As a result of checking the time series change of SPI, the change rate in the four regions was all negative and the phenolocal index was all accelerating. Among them, the rate of change was greater in inland areas such as Daegu arboretum, Palgong Mt. and Gaya mt. and the rate of change was slightly lower in the case of Juwang mt., which is somewhat distant.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.3
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• pp.213-218
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• 2014

Effects of elevated $CO_2$ on leaf phenology of Quercus acutissima were examined using open-top chambers, which had ambient and elevated $CO_2$ concentrations (ambient ${\times}1.4$, ambient ${\times}1.8$). To analyze the effect of chamber, non-treatment block was established near outside of the chambers. In 2013, budburst, leaf unfolding, coloring, and shedding were surveyed, and spring phenology was surveyed in 2014. Thermal sum (base temperature $+5^{\circ}C$) of each phenological event occurred was recorded. In addition, bud samples were collected and analyzed for carbohydrate contents in March 2014. Elevated $CO_2$ concentration advanced budburst and leaf unfolding, and delayed shedding in 2013. However, in 2014, the temperature of the spring season was high, and there was no significant effect of elevated $CO_2$ concentration on spring phenology. Carbohydrates content, such as starch, total non-structural carbohydrate and total soluble sugar, were significantly increased in response to elevated $CO_2$ concentration. It has been proposed that elevated $CO_2$ concentration could extend the growing season of temperate species with increased possibility of frost damage due to early bud opening and leaf unfolding. However, our analysis showed that the increased carbohydrate concentration in bud under elevated $CO_2$ would reduce the possibility of early spring frost damage by acting as cryoprotectant.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.343-349
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• 1988

In order to get informations for breeding early barley cultivars, the thermosensitivity and low temperature growth ability about the breeding materials vernalized were tested at the high '||'&'||'amp; low temperature and field conditions. The temperature coefficient (Q10), ratio and thermosensitivity for plant height were various among cultivars versus temperature treatments. The early cultivars had greater Q10 values and insensitive responses to temperature changes. The Q10 and thermosensitivity for the time of flag leaf unfolding were various among cultivars, but the coefficient of variation in the thermosensitivity was greater, so the character would be more useful for investigating the varietal differences. The Q10 and thermosensitivity for plant height were not significantly correlated with Q10 and thermosensitivity for the time of flag leaf unfolding. The periods from heading to flowering were 2 to 4 days at the high temperature plot, but 1 to 11 days at the low temperature plot, showing much greater variations. In general the cultivars with greater difference of heading time between the high and low temperature plots were Suwon 218, SB 76588, Oweolbori, and Jogangbori, showing the sensitive thermophase and early heading.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.98-105
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• 1989

The examination to find out how the activity of glutamine synthetase (GSA) develop in each wheat leaves during the growth period was carried out. GSA/g FW/leaf were very low at leaf differentiation stage and increased highly several times by unfolding and development of leaf, and declined deeply with the advance of senescence in each leaves. GSA/g FW/leaf were risen gradually from the every lower leaves to the every upper leaves, in consequence activity level and maximum peak per g fresh weight of 7th-flag leaves were two or three times higher than those at the 1st-4th leaves in all of 12 applied nitrogen treatments, thereupon. the highest activities per g fresh weight showed in the 8th leaves. GSA/g FW/leaf was shown two peaks in the 6th-flag leaves and one peak in 1st-4th leaves, respectively. GSA/g FW/leaf (except for senescence leaves) and GSA/plant were increased gradually to the infloresscence emerging stage and were shown the first maximum peak at 13 days before anthesis, then were declined rapidly. to the milk ripe stage (7 days after anthesis). and were shown the second maximum peak at the early dough ripe stage (22 days after anthesis) .

• Journal of Korean Society of Forest Science
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• v.105 no.3
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• pp.303-308
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• 2016

To investigate the effect of calcium chloride ($CaCl_2$) using for deicing salts in winter on gas exchange and stomatal responses of 3-year-old Prunus serrulata, we treated twice (1 L) $CaCl_2$ solution (0.5%, 1.0% and 3.0%) in the root zone before leaf unfolding. Stomatal conductance ($g_s$), photosynthetic rate ($P_n$), transpiration rate ($T_r$) and water use efficiency (WUE) in the leaves of P. serrulata were decreased with increasing of $CaCl_2$ concentration. Even though stomatal conductance and photosynthetic rate were reduced by $CaCl_2$, intercellular $CO_2$ concentration ($C_i$) in $CaCl_2$ treatments has similar or higher values compared with control. These results suggest that non-stomatal limitation as well as stomatal limitation induced the reduction of photosynthetic rate together. On the other hands, treatment of $CaCl_2$ before leaf unfolding also affected leaf morphology traits. We proposed that reductions of stomatal length and leaf size and high pore density with increasing salinity is adaptative mechanism to reduce the water loss in plant.

• Journal of Bio-Environment Control
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• v.6 no.1
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• pp.15-25
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• 1997

Plug seedlings of bell pepper(Capsicum annuum L.) were grown for 50 days in controlled environment chambers under 12 hrs per day photoperiodic condition with sixteen different day and night temperature regimes to investigate the possibility of height control. The seedlings were then transplanted to greenhouse to investigate the growth, flowering, and yield afterward. Plant height and stem length of seedlings were mainly affected by day temperature rather than night temperature. Internode elongation was suppressed by a negative DIF and was enhanced by a positive DIF even with the same average daily temperature (ADT). Leaf unfolding rate was influenced more by ADT than by DIF. Fresh and dry weights increased as ADT increased. Leaf area and stem diameter increased until temperature increased up to 24$^{\circ}C$ day and night temperature and decreased above 24$^{\circ}C$, The position at which the first flower was initiated was lowered as ADT increased. The first flower degeneration was not obvious up to 24$^{\circ}C$ ADT but increased rapidly above 24$^{\circ}C$ ADT. Seedling compactness(Dry weight per plant height :mg.mm$^{-1}$ ) was greater under -DIF than +DIF condition. In conclusion, DIF treatment was an applicable technique to control stem elongation and growth rate such as leaf unfolding rate and position at which first flower was initiated could be controlled by ADT.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.1
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• pp.115-120
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• 1981

Effect of soil water on the growth of Panax ginseng(2 years old) was investigated through pot experiment. the results were as follows. 1. Optimum soil moisture content for root yield appeared to be 65.5% of field capacity(22.1% fresh weight basis) and at 31.5%(10.7% fresh weight basis) relative growth rate was nil. 2. Under suboptimum condition of soil moisture, emergence of shoot and leaf unfolding was delayed. The rate of emergence of shoot and leaf area was also decreased while missing shoot rate was increased. 3. Root yield was positively correlated with leaf area per plant(r=0.91 **), stem diameter (r=0.73**), stem length(r=0.71 **) fresh top yield(r=0.93**) and negatively with missing shoot rate(r=-0.77**). 4. Fresh root weight showed negative correlation(r=-0.80**) with water content of root indicating that tissue is more compact when grown at sufficient water.