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用不同比例A1和B层暗棕壤混合(A1∶B=1∶2)制造土壤养分缺乏条件,栽植落叶松幼苗,通过模拟我国东北林区代表性森林凋落物淋洗液中有机酸的种类和数量,系统研究养分缺乏下,不同浓度外源有机酸对暗棕壤磷有效性和落叶松幼苗吸收运输磷素养分的影响及机理。结果表明,A1层与B层混合土壤速效磷含量降低,落叶松幼苗根系和叶片磷累积量和磷吸收效率降低,但磷利用效率增加。外源有机酸处理后,混合土壤的速效磷含量有不同程度提高,3种有机酸的作用强弱表现为琥珀酸>柠檬酸>草酸,一般以浓度5.0 mmol/L和处理20 d时提高效果最显著。有机酸不同程度提高了根系和叶片的磷累积量和磷吸收效率,但降低了磷利用效率。有机酸对磷累积量和磷吸收效率的提高程度因处理时间、有机酸浓度和种类而异:对于根系,20和30 d的结果高于10 d,叶片则10和20 d的结果高于30 d,说明处理前期磷被吸收后向叶片的转移量较多,而后期则更多地在根中积累;3种有机酸大多在10.0 mmol/L提高幅度最大;不同有机酸的促进程度为琥珀酸>柠檬酸>草酸。
Larch seedlings were planted with different ratios of dark brown soil A1 and B (A1: B = 1: 2), and the species of organic acids in the litter of representative forest litter in northeastern China were simulated And the amount of phytochemical, the effects of different concentrations of exogenous organic acids on the availability of phosphorus in dark brown soil and the uptake and transport of phosphorus by larch seedlings were studied systematically. The results showed that the content of available phosphorus in the mixed soil of layer A1 and layer B decreased, while that of larch seedling root and leaf decreased, but the phosphorus use efficiency increased. After treatment with exogenous organic acids, the content of available P in the mixed soils increased to some extent. The effect of the three organic acids was succinic acid> citric acid> oxalic acid, and the effect was generally enhanced at the concentrations of 5.0 mmol / L and 20 d Most notable Organic acids increased phosphorus accumulation and phosphorus absorption efficiency in roots and leaves to varying degrees, but decreased phosphorus use efficiency. The increase of organic phosphorus accumulation and phosphorus uptake efficiency was affected by the treatment time, organic acid concentration and species. For the root system, the results at 20 and 30 days were higher than 10 days and those at 10 and 20 days were higher than 30 d, indicating that the amount of phosphorus transferred to the leaves was higher in the pre-treatment stage and more in the roots after the phosphorus was absorbed. Most of the three kinds of organic acids increased most at 10.0 mmol / L, and the promotion rate of different organic acids was amber Acid> citric acid> oxalic acid.