在控制条件下云南松幼苗根系对低磷胁迫的响应

磷是控制生命过程的重要元素,植物在生长过程中需要大量的磷,低磷常导致一些植物发生适应性变化。云南松(PinusyunnanensisFranch.)以云南高原为起源和分布中心,其对低磷土壤环境表现出了很强的适应能力,广泛分布并正常生长于贫瘠的低磷红壤上,研究云南松对低磷环境的适应机制,对人类探索高效利用有限的磷素资源的方法具有现实意义。本实验通过对不同磷处理水平下培养的云南松幼苗根系生物量和根冠比等的研究,分析了云南松幼苗根系对低磷胁迫的响应。实验所用云南松种子采集自云南省通海县秀山森林公园内的健壮云南松林。结果表明:当磷浓度下降到0.5mmol/L时,云南松幼苗主根长度开始随磷浓度的降低而增加,根冠比随磷浓度的降低而增大,而侧根发生数没有随磷浓度的降低而显示出显著的增减规律,根系生物量也没有随磷浓度的降低而呈现出有规律的增减,根系生物量始终保持在一定的水平。进一步的分析表明:低磷胁迫下,云南松幼苗保证了物质分配对根的优先地位,以维持其根的生物量在一定水平,进而维持整个生命;云南松幼苗主要是靠主根长度的增加而不是靠侧根数量的增加来适应低磷环境。

Mechanism of Pinus yunnanensis seedlings root response to phosphorus deficiency under controlled conditions

Phosphorus is an important element that controls the process of plant life, especially during its growth phase. Low-phosphorus in the soil usually leads to adaptive changes to plants. Yunnan Plateau, being origin and its distribution range, Pinus yunnanensis Franch. reflects great capability of adapting to low-phosphorus red soil. Therefore, to study such mechanism of adaptation towards low-phosphorus becomes an important reason to understand basic resource utilization. Present study was to analyze root response of seedlings (Pinus yunnanensis Franch.) to various phosphorus levels looking at the root morphological characters, like biomass and root/shoot ratio. The test results showed that both the length of taproots and the root/shoot ratio increased as phosphorus supply decreased to 0.5mmol/L. However, the number of lateral roots and the biomass did not show any particular change. Further analysis indicated that, under phosphorus deficiency, growth continues maintaining root biomass by assuring dry matter allocation to the roots. Conclusively, such an adaptation by the seedlings does not depend on its number of lateral roots, rather on the increment of taproot's length.