不同土壤水分状况下遮蔽对棉花叶片气体交换的影响

An incubation experiment was carried out in laboratory to study the effect of temperature,moisture,phosphorus,organic matter,cropping and previous elemental sulfur application on elemental sulfur oxidation in four selected soils,fluvo-aquic soil,black soil,yellow-brown soil and red soil,In all the soils tested,sulfur oxidation rate was influenced by temperature and the temperature coefficient(Q10) values at the range from 10 to 30℃ were 4.41,,6.19 and 3.71 for the four soils,respectively.The rate of sulfur oxidation was parabolically related to soil water content.The optimum moisture content for the maximum oxiation rate was different among soils,Phosphorus increased the oxidation rate of elemental sulfur by 57.7%,33.1%,21.7% and 26.4% for the above four soils,respectively,compared with the control (no phosphorus applied).Organic material of corn straw which was gound and passed through a 0.5-mm sieve also increased th oxidation rate of elemental sulfur in the four soils by 59.8%,7.8%,39.2% and 540.4%,respectively.Elemental sulfur which was applied previously to soils significantly enhanced the oxidation of elemental sulfur subsequently added and increased sulfur-oxidizing populations such as autotrophic elemental sulfur oxidizers with pH optimum 6.8,autotrophic thiosufate oxidizers with pH optimum 6.8,heterotrophic thiosulfate oxidizers and heterotrophic sulfate producers.Cropping had little effect on elemental sulfur-oxidizing potentiality of soils.