低分子量有机酸对大豆磷积累和土壤无机磷形态转化的影响

Effects of low molecular weight organic acids on P accumulation in soybean(Glycine max L.) and inorganic P form transformation in soil

采用土培试验方法研究了低分子量有机酸(柠檬酸、草酸、苹果酸及其混合酸)对大豆磷积累和土壤无机磷形态转化的影响。结果表明:低分子量有机酸促进了大豆植株磷的吸收积累,大豆不同生育时期,不同有机酸对大豆磷的吸收积累均有促进作用,但作用效果有差异;外加低分子量有机酸使无机磷总量、难溶态磷(Ca10-P、Al-P和O-P)含量均显著降低,而可溶态磷的Ca8-P含量显著增加,柠檬酸和草酸使Ca2-P含量显著增加,表明低分子量有机酸促进了土壤难溶态磷向可溶态磷转化,作用大小顺序为柠檬酸>草酸>混合酸>苹果酸;同时,大豆根系分泌物也促进部分难溶态磷向可溶态磷转化,使无机磷总量、除Ca2-P外的其他无机磷组分均有所降低,按磷释放比例的大小来看,对大豆吸磷的贡献大小顺序为O-P>Fe-P>Ca10-P>Al-P>Ca8-P>Ca2-P。

A pot experiment with black soil was conducted to study the effects of low molecular weight organic acids （LMWOAs） citric acid, oxalic acid, malic acid, and their mixture on the P accumulation in soybean （ Glycine max L. ） and the inorganic P form transformation in soil. LM- WOAs promoted the P adsorption and accumulation in soybean plants, but the effect differed with growth stage. Applying LMWOAs decreased the contents of soil total inorganic P and unavailable P （Ca10-P, Fe-P, Al-P, and O-P） , but increased the contents of soil available P （Ca2-P and Ca8-P） , suggesting that LMWOAs promoted the transformation of soil unavailable P to available P. The effect of test LMWOAs was in the order of citric acid 〉 oxalic acid 〉 mixed acid 〉 malic acid. Moreover, the exudates from soybean roots also promoted the transformation of soil unavailable P to available P, resulting in the decrease of soil total inorganic P and its fractions except Ca2-P. The contribution of soil inorganic P fractions to the P uptake by soybean was O-P 〉 Fe- P 〉Ca10-P〉Al-P〉 Cas-P〉Ca2-P.