Abstract: Comparative experiments have been carried out to determine the height growth, photosynthesis, nutrient content and their seasonal courses for Korean pine seedlings under different light conditions. Shadings during both growing and non-growing seasons can affect the growth of Korean pine seedlings. Insufficient light illumination reduces their photosynthetic rate, nutrient uptake and normal physiological-metabolism activities. The growth retardation of virgin Korean pine seedlings under birch forest are proven to be resulted from the double effects of growing and non-growing seasons shadings. They disturb the photosynthesis and metatolism of Korean pine seedlings and lead to their growth retardation and poor regeneration.

Key words: cucumber, hypoxia stress, 24-epibrassinolide, photosynthetic characteristics, polyamine