缺铁胁迫下4种野生梨砧木介质pH值及根系Fe^(3+)还原酶活性的变化

Changes of Culture Medium pH and Roots’Fe^(3+) Reductase Activity in 4 Wild Pear Rootstocks Under Iron Deficiency

以川梨、砂梨、豆梨和杜梨为材料,研究了在缺铁胁迫下培养介质的pH值和根系Fe3+还原酶活性的变化。结果表明,缺铁胁迫使4种砧木的介质pH值于处理的第2天就迅速降低,并且一直低于低铁和正常供铁处理;而低铁处理下,介质pH值在最初几天内反而高于正常处理,至4～5d之后才逐渐低于正常供铁处理;同时,NH4+-N对降低介质pH值和缓解缺铁症状有利。4种砧木的根系Fe3+还原酶活性都随供铁浓度的增加而不同程度的增大:无铁处理下,砂梨根系Fe3+的还原能力最小、杜梨最大;而在低铁和正常供铁条件下,砂梨和川梨的还原能力最强,杜梨次之,豆梨最小。还原酶大小与症状表现之间具有一致性。

wild pear rootstocks:P.pashia Buch-Ham,P.serotina Re hder,P.betulaefolia Bunge and P.calleryana Dcne were used for studying the ef fects of iron deficiency on the medium pH and the roots’Fe 3+ reductase activity.Results showed that the medium pH fell rapidly after one day’s treatment without Fe and kept lower all along than that of low Fe tre atment (20ìmol/L)and normal treatment (40ìmol/L).During the first s everal days of the low Fe treatment ,the medium pH went up higher than that of the normal treatment until after4～5days.Furthermore,NH 4+-N in the medium was good to decrease the medium pH and then,to postpone t he chlorotic symptoms under iron deficiency.The roots’Fe 3+ reductase activity of4wild rootstocks increased while there was low or norm al Fe in medium,but their extents differed.The reductase activity of P.serot ina Rehder appeared least and that of P.betulaefolia Bunge was the highest when there was no Fe in the culture medium.However,under the low Fe or normal trea tment ,the order of the reductase activity,which was approximately consistent with appearance of the symptoms ,was P.pashia Buch-Ham,P.serotina Rehder> P.betulaefolia Bunge and then P.calleryana Dcne.