水稻磷效率差异的生理生化特性

以磷效率差异显著的IR71379—2B—10—2—3-1(磷低效型)、IR7133l-2B-2-1(中间型)及IR74(磷高效型)3个品种为供试材料，采用水培法研究了它们对磷的吸收效率、运输效率及植株体内磷的利用效率，进而研究了其对低磷胁迫的根系形态学和生理生化机制的适应性反应．结果表明：水稻磷效率的高低是由基因型对磷的吸收效率，运输效率及利用效率综合作用的结果．磷高效基因型IR74和磷效率表现为中间型的IR71331-2B-2-1具有高的磷吸收效率．旺盛的根系生长，高的根系活力，Km、Cmin小，Imax大及相对酸性磷酸酯酶(APase)活性高等是水稻对磷高效吸收的特征．但品种不同特征也有别，本试验中的IR74对磷高的吸收效率主要是由于根系生长旺盛，根系吸收面积大所致，而IR71331-2B-2-1高的磷吸收效率则主要缘于根系活力强，Imax大．低磷胁迫下，叶片中核糖核酸酶的活性也大大升高，约是对照的10～15倍，但品种间无显著差异．图2表6参21

PHYSIO-BIOCHEMICAL CHARACTERS OF P-EFFICIENT DIFFERENCES IN RICE (ORYZA SATIVA L.)

The genotypic differences in efficiency of absorption,utilization and translocation of P in three rice cultivars (IR74: P-efficient type; IR71331-2B-2-1: moderate P-efficiency type; IR71379-2B-10-2-3-1: P-inefficient type),and their responses in root architecture to low phosphorus stress and their physio-biochemcal mechanisms were studied in hydroponics culture with P-deficiency. The results showed that P efficiency of rice depended on co-ordination of P absorption efficiency,internal utilization efficiency and translocation efficiency. The IR74 and IR71331-2B-2-1 had higher P uptake efficiency. The rice genotype with higher P uptake efficiency was characterized by more extensive root systems coupled with its higher internal activity and desirable kinetic parameters of H 2PO - 4 uptake,showing lower K m and C min,but longer I max values and higher relative APase activity. However,the characteristics were different among cultivars. In this experiment,The higher P-uptake efficiency of IR74 depended on more extensive root systems and larger root surface area,but the higher P uptake efficiency of IR71331-2B-2-1 mainly resulted from higher root activity and longer I max value. The activity of RNase in rice grown in P-deficient condition was about ten to fifteen times as high as that in the control (+P),but there were no differences among the three cultivars. Fig 2,Tab 3,Ref 21