低磷胁迫不同磷效率水稻苗期根系的生理适应性研究

以P效率差异显著的IR74（P高效型）、IR71331（中间型）及IR71379（P低效型）等3个品种为供试材料，采用水培法研究了这3类水稻在低P胁迫下P的吸收、转运及利用效率等P效率差异的原因以及P吸收动力学特征参数、R／S、酸性磷酸酯酶（acid phosphoesterase,简称APase）与核糖核酸酶（ribonuclease,简称RNase）等表现。结果表明，在低P胁迫下，P效率的高低是由水稻对P的吸收率、转运率以及利用效率综合作用的结果，存在基因型差异，P高效基因型IR74和P效率中间型的IR71331具有高的P吸收率，而IR712379P的吸收率低。不同P效率水稻在低P胁迫下，其Km、Cmin、Imax、R／S与Apase相对活性等参数表现出基因型的差异，小的Km和Cmin，大的Imax和R／S及高的APase升幅是水稻对P胁迫的生理适应性特征，也是植株在低P胁迫下较为敏感生理指标。其中各类型水稻叶片中RNase活性在低P胁迫一均表现大幅度上升，在品种间无显著差异，说明该酶是逆境胁迫并非低P胁迫的特征反应。

Physiological adaptability of seeding rice genotypes with different P uptake effciency under low P-deficient stress

The genotypic differences in Puptake efficiency of three rice varieties (IR74, IR71331 and IR71379) were studied under the P-deficiency condition with hydroponics, and their adaptability to low phosphorus stress about physio-biochemical mechanisms was further studied. The results showed that rice genotypes tolerated low P stress resulted from the co-ordination of P uptake efficiency, internal utilization efficiency and its translocation efficiency. The higher P-efficiency type IR74 and the middle type IR71331 had a higher P uptake efficiency. The rice genotype with higher P-efficiency was characterized by higher activity and desirable kinetic parameters of H 2PO 4 - uptake, showing lower K m and C min, but higher I max values and relative APase activity,small amount of K m and C min. Moreover,under low P stress, the activity of RNase was about ten to fifteen times as high as that of the control (CK), but it had little genotypic differences.