中国农业科学 ›› 2017, Vol. 50 ›› Issue (7): 1223-1233.doi: 10.3864/j.issn.0578-1752.2017.07.005

• 耕作栽培·生理生化·农业信息技术 • 上一篇    下一篇



  1. 中国农业大学/教育部植物-土壤相互作用重点实验室,北京 100193
  • 收稿日期:2016-09-02 出版日期:2017-04-01 发布日期:2017-04-01
  • 通讯作者: 于福同,
  • 作者简介:徐健钦,
  • 基金资助:

Effects of BPDS-Fe(Ⅱ) on the Difference in Tolerance to Iron Deficiency of Maize Seedlings Under Different Ammonium/Nitrate Ratios

XU JianQin, CHEN XuLei, YU FuTong   

  1. China Agricultural University/Key Laboratory of Plant Soil Interaction, MOE, Beijing 100193
  • Received:2016-09-02 Online:2017-04-01 Published:2017-04-01

摘要: 【目的】作物生产中缺铁问题十分普遍,筛选耐低铁品种具有重要意义。文中采用BPDS(4,7-diphenyl- l,10-phenanthroline disulfonic acid)专性螯合Fe(Ⅱ),探究BPDS-Fe(Ⅱ)对2种玉米自交系表型特征与生理特性的影响,旨在解析2个自交系耐低铁胁迫差异及其可能机制,为筛选耐低铁品种提供理论依据。【方法】选用2个玉米自交系Wu312与Ye478,以铵硝比1﹕1与1﹕7为供氮条件,分别设置14与10个不同的BPDS-Fe(Ⅱ)浓度,观察植株表型特征,测定叶片SPAD值、地上部与根系干物重、根冠比,测定地上部铁、锰、铜、锌浓度以及新叶活性铁浓度。利用SPAD-502 plus叶绿素仪测定新叶SPAD值;将烘干样品剪碎后,用HNO3-H2O2溶液消煮,经密闭微波消煮后,用ICP-AES测定消煮液中的微量元素;取新叶尖端剪碎,称2.00 g鲜样,按照1﹕10比例加入1 mol·L-1盐酸,震荡5 h后过滤,用ICP-AES进行测定。【结果】在铵硝比1﹕1的供氮条件下,根系产生根系分泌物,根际pH在24 h内从6.0显著下降至约4.0;与对照处理(不供铁)相比,当BPDS-Fe(Ⅱ)浓度为40 μmol·L-1时,Wu312的地上部干物重显著下降了31%,Ye478则显著下降了64%;Wu312根系干物重无显著变化,但Ye478显著下降了63%;二者的根冠比均已超出正常范围(正常值:0.20—0.28),地上部与根系生长受到抑制。调整铵硝比为1﹕7后,当BPDS-Fe(Ⅱ)浓度为40 μmol·L-1时,Wu312地上部干物重是对照幼苗的8倍,Ye478则接近10倍,植株生长恢复正常;Ye478的叶片SPAD值、地上部与根系干物重、新叶活性铁浓度均显著高于Wu312,表现出生长与保绿性方面的显著优势;当BPDS-Fe(Ⅱ)浓度为0.1 μmol·L-1时,Wu312被竞争致死,无法发育出第五片叶,Ye478仍能维持生长,发育至第五片叶,叶片返绿明显;地上部铁浓度在不同自交系间无显著差异;植株地上部铁含量与锰、铜、锌浓度呈显著负相关。【结论】降低NH4+-N的供应比例有利于改善根际pH,减少根系分泌物;Ye478为耐低铁品系,Wu312为铁敏感品系;Ye478与Wu312在0.1 μmol·L-1浓度条件下表型出现最显著差异;地上部与根系生物量、叶片SPAD值是表征玉米幼苗耐低铁胁迫差异的最佳指标,根冠比以及新叶活性铁浓度是良好指标;玉米幼苗耐低铁胁迫的可能机制包括根系分泌质子,地上部将光合作用产物优先分配给根系,以及铁在植物体内的转运与再分配。

关键词: 玉米, BPDS, 二价铁, 耐低铁胁迫, 铵硝比

Abstract: 【Objective】Iron deficiency in crop production is a very common problem in both developing and developed regions. And screening of Fe-efficient genotypes has become more and more meaningful and promising. In this study, two maize inbred lines Wu312 and Ye478 were used to investigate the effects of BPDS-Fe(Ⅱ) on the phenotypes and physiological traits in maize. This work aimed at unraveling the difference in tolerance to iron deficiency between these two maize inbred lines and their mechanisms. 【Method】BPDS (4,7-diphenyl-l,10-phenanthrolinedisulfonic acid) was used to chelate ferrous iron supplied with two different NH4+-N/NO3--N ratios. Phenotypes were observed and some physiological traits were measured, including SPAD value of young leaves, dry matter weights of shoot and root, active Fe concentration in young leaves, and Fe, Mn, Cu, Zn concentrations in shoots. SPAD value was determined by SPAD-502 plus. Samples were cut into pieces and digested by HNO3-H2O2. Trace elements were determined by ICP-AES. Leaf samples of 2.00 g were soaked in 20 mL HCl (mol·L-1) and determined by ICP-AES.【Result】Root exudation was generated in two inbred lines and the solution pH decreased from 6.0 to approximately 4.0 during the last 24 hours when supplied with NH4NO3. Compared with the treatment without iron, shoot dry weights of Wu312 and Ye478 in the treatment of 40 μmol·L-1 BPDS-Fe(Ⅱ) were decreased by 31% and 64%, respectively; root dry weight of Wu312 showed no significant difference; and root dry weight of Ye478 was declined by 63%. The ratios of R/S of both inbred lines were out of range (normal value, 0.20-0.28). Solution pH has decreased by no more than one unit and plants turned to become healthy when supplied with 0.5 mmol·L-1 NH4+-N and 3.5 mmol·L-1 NO3--N. Ye478 has the ability to sustain more dry weights in shoots and roots, higher leaf SPAD value as well as active Fe concentration than Wu312, showing remarkable advantages of growth and staying green. When supplied with 0.1 μmol·L-1 BPDS-Fe(Ⅱ), Wu312 could not compete with Ye478 to produce its fifth leaf, finally turned out to be dead. However, Ye478 produced the fifth leaf and turned to be green obviously. There was no significant difference in shoot Fe concentrations between these two lines. Shoot Fe content was all negatively correlated to Mn, Cu and Zn concentrations in shoots. 【Conclusion】Reduction of the ratio of NH4+-N has improved the solution pH and inhibited root exudation. Ye478 is a Fe-efficient genotype and Wu312 is a Fe-inefficient genotype. The most significant difference of phenotypes between the two inbred lines occurred with 0.1 μmol·L-1 BPDS-Fe(Ⅱ). Dry matter weights of shoot and root, together with leaf SPAD value were identified to be most suitable physiological traits charactering the tolerance to iron deficiency of maize seedlings. R/S ratios and active Fe concentration were found to be good indicators. Possible mechanisms contained the release of protons, preferential allocation of biomass to roots, and the translocation and redistribution of iron.

Key words: maize, BPDS, ferrous iron, tolerance to iron deficiency, ammonium/nitrate ratios