| The research was done in order to explore the potential allelopathy in the Pinus koraiensis plantations, the mixed stands of Pinus koraiensis and Tilia amurensis, Pinus koraiensis and Betula costata, the studies selected extracts of three tree species fresh leaves, litter, Pinus koraiensis half decaying litter, and three mixed stands surface layer soil, these materials were used to test there effects on the seed germination, seedling and4-year-old Pinus koraiensis growth in according with the design of concentration gradient1:10,(1:30),1:50,1:100. And the results are as follows:(1) The litter and soil extracts of the Pinus koraiensis, Tilia amurensis and Betula costata trees have allelopathic effects on Pinus koraiensis growth. The fresh leaf, litter, surface layer soil, half decaying litter had significant inhibition effects on the seed germination,1-year-old and4-year-old Pinus koraiensis seedlings growth at the concentration1:10. With concentration reducing, the inhibition effects of aqueous extracts gradually decreased, disappeared and even some extracts would promote Pinus koraiensis growth at lower concentration. It showed that significant differences between higher concentration1:10and lower concentration1:100(P<0.05) generally. Overall there was less difference between1:30and1:50of different extracts effects on the seed germination, seedling, and the same as extracts effects on4-year-old Pinus koraiensis growth between1:50and1:100concentration.(2) The litter and soil extracts of the Pinus koraiensis aqueous extracts of Pinus koraiensis mainly inhibited the seed germination,1-year-old and4-year-old Pinus koraiensis seedling growth at high concentration, especially the Pinus koraiensis plantation soil and litter showed strong inhibition effects at concentration1:10, the soil aqueous extracts had strongest inhibition effects on the seed germination and1-year-old seedling height growth, the litter aqueous extracts had strongest inhibition effects on the growth of4-year-old Pinus koraiensis seedling height and the basal diameter growth, both two aqueous extracts showed significant inhibition effects on several physiological indexes such as photosynthetic rate of4-year-old Pinus koraiensis seedling. The Pinus koraiensis fresh leaves and half decaying litter had strongest promotion on the seed germination at concentration1:100, and the fresh leaves also showed strongest promotion effects on1-year-old seedling growth and4-year-old seedling growth such as biomass and root length.(3) The litter, soil and fresh leaves extracts of the Tilia amurensis mainly showed inhibition effects on the seed germination,1-year-old Pinus koraiensis seedling growth and4-year-old Pinus koraiensis seedling growth at the high concentration, the Pinus koraiensis-Tilia amurensis mixed forest soil extracts showed inhibition effects on the seed germination and1- year-old seedling growth and4-year-old seedling physiological indexes, the litter extracts showed the same effects on4-year-old seedling growth, the fresh leaves extracts showed strongest inhibition effects on the seed germination,1-year-old and4-year-old seedling growth at concentration1:10. With reducing concentration, the inhibition effects of the litter, soil and fresh leaves extracts gradually decreased, the litter extracts showed significant promotion effects on seed germination,1-year-old seedling root length growth and biomass accumulation.(4) The litter and soil extracts of the Betula costata mainly showed significant inhibition effects on the seed germination,1-year-old and4-year-old Pinus koraiensis seedling growth at the high concentration, the Betula costata litter extracts had strongest inhibition effects on the seed germination,4-year-old seedling growth and physiological indexes such as basal diameter growth, chlorophyll content and photosynthetic rate at concentration1:10, at the same concentration the Pinus koraiensis-Betula costata mixed forest soil inhibited seed hypocotyl length, radicle length, the seedling height and root length growth. At lower concentration, the litter promoted the seed germination and4-year-old Pinus koraiensis seedling growth indexes, other extracts showed no significant effects on the seed and seedling growth. |
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