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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,以探讨利用有机酸提高养分缺乏下落叶松幼苗抗土壤贫瘠能力的可行性及机制。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5.0mmol/L和处理20d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,20d和30d的结果高于10d,叶片则为10d和20d的结果高于30d,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种有机酸大多在浓度为10.0mmol/L时提高幅度最大;不同有机酸的促进程度为琥珀酸>柠檬酸>草酸。因此,外源有机酸能通过提高落叶松幼苗对养分缺乏土壤中磷的吸收能力,促进磷的积累,进而提高苗木对养分缺乏土壤的耐性和适应能力。
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 organic phosphorus, the effects of different concentrations of exogenous organic acids on the availability of phosphorus in dark brown soil, the absorption of larch seedlings and the transport of phosphorus nutrients were systematically investigated to explore the mechanism of using organic acids to enhance the nutrient-deficient larch seedlings Feasibility and mechanism of soil infertility. 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. Generally, the effect of increasing the concentration of 5.0mmol / L and 20d Significant. Organic acids increased phosphorus accumulation and phosphorus absorption efficiency in roots and leaves to varying degrees, but decreased phosphorus use efficiency. Organic acids on phosphorus accumulation and phosphorus uptake efficiency of the treatment time, the concentration of organic acids and species vary: for the root system, 20d and 30d results higher than 10d, leaves 10d and 20d results higher than 30d, indicating In the early stage of treatment, the amount of phosphorus transferred to the leaves was more, and the latter was more accumulated in the roots. Most of the three kinds of organic acids had the highest increase at the concentration of 10.0 mmol / L. The promotion of different organic acids was amber Acid> citric acid> oxalic acid. Therefore, the exogenous organic acids can promote the accumulation of phosphorus by raising the phosphorus absorption capacity of larch seedlings to the nutrient-deficient soil, and then improve the tolerance and adaptability of seedlings to nutrient-deficient soils.