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Effects of drought stress and nitrogen fertilization on growth and physiological characteristics of Pinus densiflora seedlings under elevated temperature and CO2 concentrations

XV World Forestry Congress, 2-6 May 2022










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    Genetic diversity and physiological response to drought stress of Chamaecyparis obtusa from six geographical locations
    XV World Forestry Congress, 2-6 May 2022
    2022
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    Water deficit is a critical factor obstructing the growth and survival of plant. Therefore, researchers have been trying to develop drought-resistant varieties. To find indicators of drought stress-tolerance of cypress (Chamaecyparis obtusa), we analyzed the response of cypress seedlings from six provenances of Korea (Jeju, Suwon, Seoul, Seongnam, Yong-in, and Osan) to drought stress. Additionally, the genetic diversity of C. obtusa from the six provenances were determined using microsatellite markers. We confirmed that populations from Suwon and Seongnam were relatively separated from other populations through genetic distance and cluster analysis. We examined their physiologic and metabolic responses after drought treatment for five weeks. Almost all of the cypress seedlings showed a reduced shoot growth rate under drought treatment compared to controls. In addition, temperature of drought treated cypress seedling leaves was 1.2-2°C higher than that of the controls. Almost all of the drought stress-treated cypress showed increased carbon metabolite contents and pigments. In particular, the cypress seedlings from Osan showed the highest increase in all of the measured metabolites. Therefore, it is suggested that the seedlings from Osan are susceptible to drought stress. Conversely, the seedlings from Jeju, Suwon, and Yong-in showed a lower sensitivity to drought treatment. These results indicate that the cypress trees from the six provenances have a different response to drought stress. In addition, it is confirmed that previously identified indicators of drought stress, especially those that measure total soluble sugar, carotenoid, and H2O2, can be used in the selection of drought resistance cypress. These findings may useful in studies concerned with the metabolic and physiological responses of young cypress to drought. Keywords: Climate change, Genetic resources, Research ID: 3618007
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    The early growth performances of Pinus densiflora and Larix kaempferi seedlings under open-field experimental warming and precipitation manipulation
    XV World Forestry Congress, 2-6 May 2022
    2022
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    This study aimed to investigate the effects of climate change on the survival and growth performance of Pinus densiflora and Larix kaempferi seedlings using open-field experimental warming and precipitation manipulation. We measured the survival rate, root-collar diameter, and height, and then calculated the seedling quality index (SQI) of 2-year-old seedlings under 6 treatments [2 temperatures (TC: Control; TW: Warming) × 3 precipitation manipulations (PC: Control; PD: Decreased; PI: Increased)] and performed a two-way ANOVA to test for differences. The air temperature of the warming plots was 3°C higher than that of the control plots, while the precipitation manipulation plots received ±40% of the precipitation received by the control plots. Temperature and precipitation treatments did not significantly affect the survival rate of P. densiflora; however, the SQI of P. densiflora decreased with increasing precipitation. In contrast, the mortality rate of L. kaempferi increased with increasing temperature and decreasing precipitation. Furthermore, in L. kaempferi, TC × PI treatment resulted in the lowest SQI with a significant interaction effect observed between the two factors. In summary, low seedling production and quality should be expected in P. densiflora as precipitation increases and in L. kaempferi as temperature increases or precipitation decreases. These results indicate species-specific sensitivities to climate change of two plant species at the nursery stage. With the occurrence of global warming, the frequencies of drought and heavy rainfall events are increased, and this could affect the survival and seedling quality of tree species. Therefore, it is necessary to improve nursery techniques by establishing new adaptation strategies based on species-specific growth performance responses. 1) Keywords: Climate change ID: 3622385
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    Environmental stresses do not always adversely affect seedling growth
    XV World Forestry Congress, 2-6 May 2022
    2022
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    Excessively high temperatures and droughts after winter dormancy breaking can affect the growth and mortality of seedlings. An open-field experiment was conducted to understand the growth and mortality of Larix kaempferi seedlings to spring warming and drought treatments, and further to explore if seedlings could recover the growth capability when the treatments ceased. One-year-old seedlings were subjected to two temperature levels (ambient temperature and infrared heater warming of 4 °C compared to ambient temperature) and two precipitation levels (ambient precipitation and drought) for four weeks. Warming and drought treatments decreased the height and root collar diameter of seedlings throughout the period. After the cessation of treatments, mortality rates continued to increase in the drought-treated plots until the end of the growing season in November; the combination of warming and drought treatments had the highest mortality rates, followed by the drought treatment, the control, and the warming treatment. However, the combination of warming and drought treatments increased the biomass accumulation, seedling height, and root collar diameter at the end of the growing season. This indicates that the reduced number of seedlings per plot due to the increased mortality may reduce the negative effects of warming and drought on seedling growth through alleviating resource competition among seedlings. This study shows the growth of Larix kaempferi seedlings could decline under warmer and drier conditions, and such effects are likely to be mitigated by the decreased density due to the increased mortality rates. Keywords: climate change; drought; growth; Larix kaempferi; mortality ID: 3622945

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