盐碱地柳枝稷根际微生态特征与磷高效利用机制研究

Phosphorus is one of the necessary nutrition for crops. Under the condition of saline soil, it is not easy for the crops to absorb the phosphorus in soil, because the salt and poor soil will reduce the effectiveness of phosphorus. The activation and efficient utilization of soil phosphorus is inseparable from the microbial environment of crop rhizosphere, and it is very important to reveal the rhizosphere mechanism of soil utilization in saline soil. Energy crops switchgrass has advanced root system and can form mycorrhiza, which has strong resistance to saline soil, so it can be planted in saline soil. At present, the research about planting switchgrass in saline-alkali soil mainly focused on its ecological adaptability, yield and quality control and salt-tolerant physiology. There are few research reports on the micro-ecological characteristics and the utilization of phosphorus in the rhizosphere of switchgrass in saline soil. Therefore, based on the previous research, this project adopt the method of combining with the indoor simulation and field orientation research, then use the techniques about modern root biology and molecular biology to study the microecological characteristics in the root of switchgrass in saline soil. The objective is to analysis the influence of soil phosphorus nutrition on root morphology, physiological traits and rhizosphere microbial diversity, reveal the coordination mechanism about the efficient utilization of phosphorus root system and its physiological response, explore the rhizosphere bio-interaction mechanism of switchgrass phosphorus under salt and alkali conditions. The results would provide theoretical basis and technical support for the bio-improvement of saline-alkali soil and the efficient utilization of phosphorus resources.

磷是作物必需的大量营养元素, 在盐碱地条件下,因盐碱和不良土壤环境因素导致磷的有效性降低，土壤磷的活化和高效利用与作物根际微生态环境密不可分，揭示盐碱土壤磷高效利用的根际作用机制对于盐碱地生物改良具有重要意义。能源作物柳枝稷根系发达、并能形成菌根，具有较强的抗逆性，可在盐碱地种植,并表现出较好的生态适应性，目前对盐碱地柳枝稷根际微生态特征以及磷素利用特性的研究还鲜有报道。因此，本项目在前期研究基础上，采用室内模拟与田间原位研究相结合的方法，应用现代根系生物学与分子生物学技术，研究盐碱地柳枝稷根际微生态特征，分析土壤磷营养变化对作物根系形态构型、生理性状以及根际微生物多样性的影响，揭示柳枝稷高效利用磷的根系形态构型与生理反应的协调机制，探讨盐碱条件下柳枝稷磷高效利用的根际生物互作机制，为盐碱地生物改良和磷高效利用提供理论依据和技术支撑。

土壤磷的活化和高效利用与作物根际微生态环境密切相关，本项目针对盐碱地柳枝稷磷高效利用问题，采用室内模拟与田间原位研究相结合的方法，应用现代根系生物学与分子生物学技术，研究了盐碱地柳枝稷根际微生态特征，初步揭示了盐碱条件下柳枝稷磷高效利用的根际互作机制，为盐碱地生物改良和磷高效利用提供了理论依据和技术支撑。主要研究结果如下：盐碱条件下随着供磷水平的提高，柳枝稷根际、近根际、非根际土壤均表现为pH减小，全磷和速效磷含量显著提高。土壤ACP活性在柳枝稷根际最高，且随着供磷量的增加，土壤ACP活性降低。土壤中Ca2-P、Ca8-P、Al-P、Fe-P、O-P含量均随供磷水平的增加而增大。两种生态型柳枝稷品种的生长和生理特性对盐碱和低磷胁迫的响应不同，Alamo加倍体植株生长和生理活性受抑制的程度低于Pathfinder，表现出较强的抗逆性和较高的磷吸收利用效率。低磷胁迫条件下，品种Alamo加倍体具有较大的根表面积、根体积和较强根系活力、叶面积、叶绿素含量、净光合速率和酸性磷酸酶活性，从而提高了其磷素吸收利用效率。在盐碱地种植柳枝稷和适当增施磷肥能显著降低表层土壤pH值和全盐含量，从而改善土壤微环境，促进磷素活化和吸收。施磷在一定程度上降低了柳枝稷根际土壤丛枝菌根真菌（AMF）的α多样性指数，但适当施磷增加了柳枝稷菌根侵染率，促进了柳枝稷根系有机酸分泌，从而降低了根际土壤pH，提高了土壤磷酸酶活性和有效磷含量，促进了盐碱地柳枝稷的生长和产量提升，提高了柳枝稷磷素吸收利用效率。与高地型Pathfinder品种柳枝稷相比，同等施磷条件下，低地型柳枝稷品种Alamo磷素吸收利用效率更高。