Changes on Initial Growth and Physiological Characteristics of Larix kaempferi and Betula costata Seedlings under Elevated Temperature

Larix kaempferi and Betula costata seedlings were grown under an elevated temperature () for four weeks to understand initial changes on physiological characteristics caused by temperature rising in connection with global warming. At the end of the treatment, growth performance, leaf pigment content, antioxidative enzyme activities and malondialdehyde (MDA) content were measured and analyzed. Relative growth rates of the height of two tree species grown under elevated temperature () were lower than those of control () and dry weights of leaves, stems and roots were also reduced at higher temperature. Particularly, the root growth reduction of two tree species increased markedly at over the study period, which increased the ratio of shoot to root. Under higher temperature, leaf pigment contents decreased, whereas anti-oxidative enzyme activities such as ascorbate peroxidase (APX) and catalase (CAT) increased as compared with the control. But MDA content was not affected by elevated temperature. In conclusion, the elevated temperature leads to root growth reduction, restriction of nutrient uptake from soil and the reduction of leaf pigment contents, which can inhibit the aboveground growth. In addition, higher temperature might act as a stress factor that causes growth reduction through the increase of energy consumption during a growth period.