磷高效基因型小麦对缺磷胁迫的根际适应性反应

摘要

采用根箱分隔栽培试验法，进行了磷高效与磷低效小麦基因型根际土壤pH与有效磷变化的研究。结果表明：小麦根际土壤pH和有效磷含量皆明显低于外围土壤，表现出明显的根际效应特征；磷高效基因型小麦的根际pH和有效磷含量明显低于磷低效基因型，pH变异范围和磷素亏缺区也表现出明显较大。为了进一步验证磷高效小麦基因型的这一根际特征，同时进行了施用水溶性、枸溶性磷肥的试验研究。结果表明，以水溶性磷肥对根际pH和有效磷分布的影响最大，表现为磷高效和磷低效基因型间根际pH和有效磷水平差异明显变小，而枸溶性磷肥对根际效应略有影响，但仍表现出较宽的pH变异和磷素亏缺范围，磷高效基因型表现出根际范围的pH和有效磷含量明显低于磷低效基因型，说明磷高效基因型小麦对枸溶性磷肥具有较高的活化吸收能力。同时也证明根际pH降低是磷高效基因型小麦对土壤缺磷的一种诱导性根系适应机制，对促进根际土壤难溶态磷的有效活化、吸收具有重要作用%With a newly developed rhizobox system,studies on changes of pH and available phosphorus (P) in the rhizophere of P-efficient wheat genotype were carried out.The results indicated that pH value and available P in the rhizosphere were much lower than that in the bulk soil.pH values and contents of available P for efficient genotype were much lower than that for inefficient one.The similar results appeared as above when P fertilizers supplied but water-soluble phosphate had more impact on pH values and available P in the rhizosphere than citvate soluble phosphate.This has been proved that P-efficient genotype of wheat possess some special mechanism to utilize soil unavailable P or citrate soluble phosphate in calcareous soil efficiently through some changes of rhizosphere effect.Simultaneously,it has been demonstrated that pH reduction in the rhizosphere is one of the root-induced mechanisms of P-efficient wheat genotype for the stress of P deficiency,which results in mobilization and efficiently uptake of P from calcareous soil.