稻田生态系统中植硅体的产生与积累——以嘉兴稻田为例

The production and accumulation of phytoliths in rice ecosystems: a case study to Jiaxing Paddy Field

在嘉兴杭嘉湖平原实验基地,以嘉花11、浙粳37、宁81、祥湖301、秀水09等5个品种水稻及其0—10cm表层土壤为研究对象,运用微波消解和Walkley-Black的方法,研究了稻田生态系统中植硅体的产生和积累通量,为了解植硅体在稻田生态系统硅和碳生物地球化学循环中的作用提供科学参考。结果表明:(1)植硅体含量在不同品种水稻中嘉花11、宁81和祥湖301高于浙粳37和秀水09,在各器官中鞘>叶>茎>根>穗;(2)水稻植株植硅体产生通量为1269.59 kg hm-2a-1,其中地上部分为1203.44 kg hm-2a-1,地下部分为66.15 kg hm-2a-1,在种植50a的稻田0—10cm土壤中的积累通量为40.38 kg hm-2a-1;(3)选择嘉花11等高植硅体含量品种进行推广种植,对提高水稻植硅体产生通量及其包裹大气中CO2通量有很大的作用。

Phytolith, the opal of amorphous silica formed in plant tissues （e.g., cell walls, cell luminas, and intercellular spaces typically near evaporating surfaces）, presents in most plants. This study selected plants of five rice cuhivars of Jiahuall, Zhejing37, NingS1, Xianghu301, Xiushui09 and their corresponding surface soils （ 0-10 cm） at the experiment base of Hangjiahu plain in Jiaxing, to investigate the fluxes of the phytolith production and accumulation in rice ecosystems. The main purpose of this study is to provide scientific reference for understanding the role of phytoliths in biogeochemieal cycles of silicon and carbon. Results showed that the phytolith content varied from 40.54 to 51.40 g/kg, with an average of 46.54 g/kg, being higher in Jiahuall, Ning81 and Xianghu 301 than that in Zhejing37 and Xiushui09 It decreased in the following order among different organs： sheath 〉 leaf 〉 stem 〉 root 〉 grains. There was a positive correlation between phytolith content and total SiO2 in rice and soil, R2 = 0.8156 （P〈0.01） and R2 = 0.355 （P〈0.05）, respectively. The total production flux of phytoliths for whole plants was 1269.59 kg hm-2 a-1. The aboveground and underground phytolith production flux was 1203.44 and 66.15 kg hm-2 a-l , respectively. The flux of phytolith production differed in different rice cultivars. The flux of aboveground and underground phytolith production in Jiahual 1 was higherthan that of the other. The flux of phytolith production from root, stem, sheath, leaf and grains is 66.15, 131.65,491.08, 185.36 and 395.35 kg hm-2 a-1, respectively. In rice ecosystems with 50 years of cultivation, the phytolith accumulation flux in surface soil （0--10 em） was 40.38 kg hm-2 a-1, which was equivalent to the flux of root phytolith production, implying that the rice straws are rarely returned to the paddy soil. The production flux of rice phytolith to sequestrate the atmospheric CO2 was 46.55--279.31 kg hm-2 a-1 and the accumulation flux of paddy soil phytolith sequestrate the atmospheric CO2 was 1.48--8.88 kg hm-2 a-1. It was promising to improve the fluxes of phytolith production and the phytolith to sequestrate CO2 by selecting high phytolith content rice rarities such as Jiahual 1.