Biological Effect Of Aqueous Extracts Of Larch,Korean Pine And Mongolian Scots Pine Litter Needles On Seed Germination

Forest litter has important effect on seed germination and seedling growth by physical interference, biochemical action and change of soil physicochemical property. In this study, using non-dormancy cabbage seeds as control, the aqueous extracts of un-decomposed and semi-decomposed needles of larch, Korean pine and Mongolian Scotch pine were used to test their effects on seed germination of cabbage, Koyama spruce and larch. The results were as follows:(1) Extracts of semi-decomposed needles significantly accelerated seed germination, while extracts of un-decomposed needles had no significant effect, indicating that allelochemicals and nutrients in the extracts might have some interaction with metabolites induced by seed germination.(2) Inhibitory substances were detected in extracts from needles of all3species, of which higher contents were detected in extracts of un-decomposed needles. Compared to lower concentration (5-20g.L-1), higher concentration (40g.L-1) extracts significantly inhibited seed germination, particularly for germination index..(3) The influencing pattern of needles extracts on larch and Koyama spruce seeds was different from that on cabbage seeds, suggesting that the affecting mechanism in tree seeds differs from that in cabbage seeds.(4) Needles extracts of both Korean pine and Mongolian Scotch pine affected seed germination in the following pattern:stimulating in low concentration, inhibiting in moderate concentration and again stimulating in high concentration; while it was different in Koyama spruce, which undergone an influencing pattern of "high-lower-higher-lower".For the germination of larch seeds,40g.L-1both un-decomposed and semi-decomposed needles extracts were the best. While for the germination of Koyama spruce seeds,10g.L"1semi-decomposed needles extracts and0.5-1.0g.L-1un-decomposed needles extracts were the best.These results has established important theoretical basis for better understanding of the possibility of needles covers used in nursery seedbeds.