• ISSN 1008-505X
  • CN 11-3996/S

土壤中高磷水平和轻度干旱条件下黄腐酸促进土壤磷有效性及玉米生长和磷吸收的效应

Fulvic acid promotes soil phosphorus availability and maize growth and phosphorus uptake under light drought and medium and high soil phosphorous content

    摘要
  • 摘要:
    目的 干旱和缺磷影响土壤磷有效性并限制旱区作物生长。研究不同磷水平和水分条件下黄腐酸对提高土壤磷有效性、植物生长和磷吸收的作用效果，对旱区磷养分高效利用和农业发展有着现实意义。
    方法 以玉米为供试作物，黄绵土为基质进行了三因素三水平盆栽试验。磷素低、中、高水平P 30 mg/kg (P30)、60 mg/kg (P60) 和120 mg/kg (P120)；水分正常供水(W1)、轻度干旱(W2) 和中度干旱(W3) 的含水量为田间持水量的75%、60%和45%；黄腐酸三个施用水平为0 (FA0)、50 (FA1) 和100 mg/kg (FA2)。玉米生长60天后收获，测定玉米株高、生物量和磷含量，同时测定土壤pH、速效磷、磷组分、碱性磷酸酶活性和根际有机酸。
    结果 黄腐酸提高了干旱条件下的土壤磷有效性，其效应与磷水平和水分条件有关。在P60W2和P120W2条件下，FA1和FA2处理通过酸化效应使得土壤pH显著降低 0.14～0.21个单位，驱动土壤速效磷和活性磷含量分别增加15%～19%和43%～47%；在P60W3条件下，FA2处理增加酒石酸盐含量和土壤速效磷含量，且酒石酸盐含量与土壤速效磷含量呈显著正相关，表明黄腐酸还可以通过促进根际有机酸的分泌提高土壤磷有效性。在任意磷水平的干旱条件下，黄腐酸对土壤碱性磷酸酶活性的作用效果并不显著。在P30W2条件下，FA1和FA2处理降低了玉米各部位的生物量(35%～39%)和植物磷累积量(20%～38%)。但在P60W2和P120W2条件下，施用黄腐酸对玉米生长和磷吸收有促进效果。在P60W2条件下FA2处理增加磷吸收效率38%，P120W2条件下FA1处理增加玉米株高10%，FA2处理增加根磷含量12%。
    结论 在干旱且土壤磷素为中、高水平下，施用黄腐酸可通过酸化效应和有机酸调控效应，驱动土壤磷素形态转化，增加土壤速效磷和活性磷含量，提高土壤磷有效性，但仅在轻度干旱条件下，施用黄腐酸能促进玉米生长和磷吸收。

     

    Abstract:
    Objectives Drought and phosphorus (P) deficiency seriously effect soil P availability and restrict crop growth. This study aimed to reveal the effects of fulvic acid (FA) on soil P availability, maize growth and P uptake under drought stress with different P levels, in order to provide a theoretical basis for P-utilization efficiency and agricultural development in arid regions.
    Methods A pot experiment with three factor-three level design was conducted using maize in a loess soil. The low, medium, and high P treatment levels was 30 (P30), 60 (P60), and 120 mg/kg (P120); the normal (W1), mild drought (W2), and moderate drought (W3) water conditions were 75%, 60%, 45% of field capacity, respectively; and the three application rates of FA were 0 (FA0), 50 (FA1), and 100 mg/kg (FA2), respectively. The maize was harvested after 60 days of growth for measurement of plant height, biomass and P concentration. At the same time, soil pH, Olsen-P and P fraction concentration, alkaline phosphatase activity and rhizosheath carboxylates were determined.
    Results FA enhanced soil P availability under drought conditions, and its effect was related to P application and water conditions. At P60W2 and P120W2, FA1 and FA2 treatments significantly reduced soil pH by 0.14−0.21 units through acidification effects, resulting in 15%−19% and 43%−47% increases in soil Olsen-P and labile P concentration, respectively. At P60W3, FA2 treatment increased tartrate and Olsen-P concentration. Moreover, there was a positive (P<0.05) correlation between tartrate and Olsen-P concentration, indicating that fulvic acid could improve soil P availability by promoting the secretion of rhizosheath carboxylates. Under drought conditions at any P treatment level, FA had no significant effect on soil alkaline phosphatase activity. At P30W2, FA1 and FA2 treatments reduced various parts of maize biomass (35%−39%) and plant P content (20%−38%). However, at P60W2 and P120W2, FA promoted maize growth and P uptake. At P60W2, applying FA2 increased P-uptake efficiency by 38%. At P120W2, applying FA1 increased maize plant height by 10%, and applying FA2 increased root P concentration by 12%.
    Conclusions Under drought and medium to high soil P conditions, the application of fulvic acid can drive the transformation of soil P forms through acidification effects and the regulation of rhizosheath carboxylates, increasing soil Olsen-P and labile P concentration, and thus improving soil P availability. However, only under mild drought conditions can the application of fulvic acid promote maize growth and P uptake.

     

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