[Relationship between SO2 exposure mode and Chinese pine growth].

Chinese pine seedling, which age is 87 days, are exposed to SO2 in three treatments for 60 days from July 1, 2002 to August 29, 2002. In treatment 1 and treatment 2, the concentration of SO2 were 0.1 mg x m(-3) and 0.2 mg x m(-3), respectively. In treatment 3, the concentration of SO2 were 0.5 mg x m(-3) for 6 hours and 0.1 mg x m(-3) for 18 hours per day. In treatment 1, the abnormity of stomata guard cell and leaf colour are not observed. There are no significant difference of chlorophyll content, carotenoid content of leaf, photosynthetic rate, transpiration rate, relative growth rate, and dry weight per plant compare with control, but the sulfur content of leaf increased 17% compare with control, the amount of potassium ion leaching from leaf increased 22% compare with control. In treatment 2, the abnormity of stomata guard cell and leaf colour are not observed. There are no significant difference of chlorophyll content, photosynthetic rate and transpiration rate compare with control. But compare with control, the carotenoid content of leaf decreased 5%, and the sulfur content of leaf increased 92%, the amount of potassium ion leaching from leaf increased 67%, dry weight decreased 4.5% per plant, the relative growth rate decreased 0.6 mg x(gxd)-1. In treatment 3, the abnormity of stomata guard cell and leaf colour are observed. The chlorophyll content were similar with control, but compare with control, the carotenoid content of leaf decreased 21%, and the sulfur content of leaf increased 104%, the amount of potassium ion leaching from leaf increased 89%, photosynthetic rate decreased 5%, transpiration rate increased 8%, the dry weight decreased 7.6% per plant, the relative growth rate decreased 1.3mg x (gxd)-1.

Effects of red-yellow soil acidification on seed germination of Chinese pine.

Acid treatments significantly change the physical and chemical properties of red-yellow soil by lowering its pH value and leaching out aluminum(Al) ions that are harmful to the growth of plants. The structure of soil will be damaged, resulting in higher viscosity, higher water retention rate and lower air permeability of the soil. The germination rate of Chinese pine(Pinus tobulacformic Carr.) seeds sowed in soil treated with sulphuric acid(H2SO4) decreased compared to that for untreated soil. The direct cause was the large amount of Al ions leached out because of low pH values(> or = 3.5). The added acid decreased the soil aggregation and increased the number of micro-aggregates(under 250 microns in diameter). Such changes increased the soil's viscosity, which tied the pine needles to the soil after the seeds had germinated and prevented the seedlings from fully developing.