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基于叶片电信号边际谱熵的玉米耐盐碱性无损评价方法

2018-02-28赵燕燕杨运经杜光源

农业工程学报 2018年2期
关键词:盐碱边际电信号

刘 锴,赵燕燕,习 岗,杨运经,杜光源



基于叶片电信号边际谱熵的玉米耐盐碱性无损评价方法

刘 锴1,赵燕燕2,习 岗1※,杨运经3,杜光源3

(1. 西安理工大学理学院,西安 710054; 2. 郑州工业应用技术学院基础教学部,郑州 451100; 3. 西北农林科技大学理学院,杨凌 712100)

为了探索能够早期、灵敏、在位和无损检测与评价植物耐盐碱性的方法,将NaCl、Na2SO4、NaHCO3和Na2CO3配置成复合盐碱溶液对耐盐碱性较弱的玉米品种郑单958和耐盐碱性较强的玉米品种名玉20的玉米幼苗进行盐碱胁迫,采集了盐碱胁迫过程中郑单958和名玉20幼苗叶片电信号,应用HHT(Hilbert-Huang transformation)方法得到了2种玉米叶片电信号的边际谱,分析了盐碱胁迫过程中2个玉米品种叶片电信号边际谱熵MSE(marginal spectrum entropy)变化的差异和生物学意义。结果显示:盐碱胁迫过程中,郑单958叶片电信号的MSE表现出不断下降的趋势,叶片中丙二醛MDA(malondialdehyde)含量迅速升高;名玉20的MSE表现出波动性的变化,MDA含量变化不大,表明郑单958叶片细胞的离子跨膜运输被抑制,名玉20的叶片细胞存在着复杂的代谢调节,盐碱胁迫造成的叶片细胞膜脂过氧化可能是叶片电信号MSE变化的原因。研究发现,盐碱胁迫下耐盐碱性不同的2个玉米品种的叶片电信号响应指数RI(response index)差异明显,在胁迫2、3和4 d时郑单958的RI值分别比名玉20增长了42%、193%和332%。根据RI值的大小有可能对盐碱胁迫下玉米叶片细胞离子运输和细胞膜伤害的影响程度进行灵敏和早期的定量诊断,进而实现对玉米幼苗期耐盐碱性强弱的在位和无损伤的评价。

胁迫;作物;无损检测;玉米;盐碱胁迫;电信号;边际谱熵;评价

0 引 言

目前,全球范围的土壤盐碱化不断扩大[1]。土壤盐碱化对植物会形成盐胁迫导致渗透胁迫和离子毒害,还会形成碱胁迫下pH值升高造成营养胁迫[2-4],严重影响植物生长[5]。挖掘植物的耐盐碱能力, 开发和选育耐盐碱植物品种正成为研究的热点[6]。

要开发和选育耐盐碱性植物,必须首先建立能够对植物耐盐碱性强弱进行准确判断的评价方法。在现有研究中,植物耐盐碱性评价采用的是基于多个形态指标和生理生化指标的隶属函数法、聚类分析法和灰色关联度分析法等综合数量分析方法[7-11]。这些评价方法需要测量的指标多,样品量大,周期长,不能进行早期诊断,而且许多指标必须通过试管试验的破坏性测量来获取,无法做到无损检测。

由于植物抗逆性是由多因素控制的,在细胞层面上体现的综合性状,是植物在逆境下通过代谢调节维持细胞功能状态的能力[12-13],植物耐盐碱性应该基于盐碱胁迫下植物细胞发出的生命信息,根据细胞代谢调节和功能状态的变化程度来评价,其评价指标必须能够实现活细胞或组织的无损和在位检测,此外,还要求做到反应灵敏,可以进行早期诊断。显然,现有评价方法难以满足这些要求。

植物电信号是来自活细胞的生命信息,大量研究表明,植物电信号与化学信号、力学信号和水信号等构成了植物的信息系统[14]。植物电信号一方面在组织和器官中传递信息流,另一方面直接参与代谢控制[15-19],调节呼吸代谢、光合作用、水分吸收和气孔导度变化等核心生理过程,维持细胞的功能状态[20-22]。分析和解读植物电信号能够对植物叶片细胞代谢调节和功能状态进行定量诊断和评价,并做到实时、在位和无损检测[22-25]。因此,研究盐碱胁迫下植物叶片电信号的变化规律及其生物学意义有可能为植物耐盐碱性的无损检测与评价提供一种新方法,然而有关研究未见报道。

植物叶片电信号边际谱是基于HHT(Hilbert-Huang transformation)方法获得的信号在频域上的分布[26],边际谱熵MSE(marginal spectrum entropy)是边际谱分布混乱程度的量度,其综合反映了叶片细胞群跨膜电位和细胞之间的电偶联状况[27]。玉米是全球主要的粮食作物,其对盐碱胁迫十分敏感[7,28],研究玉米耐盐碱性评价方法具有重要的现实意义。鉴于此,本文对比研究了盐碱胁迫下2个玉米品种叶片电信号边际谱MSE变化的差异及其生物学意义,探讨了基于叶片电信号边际谱MSE评价植物耐盐碱性的可行性,为开发能够早期、灵敏、快速和无损伤在位检测和评价植物耐盐碱性的技术提供参考。

1 材料与方法

1.1 材料选择与培养

玉米品种郑单958和名玉20为种子市场购得。试验前选取2个品种外观一致、颗粒饱满的玉米种子各200粒,用蒸馏水洗掉外层红色包衣,用质量分数为0.2%的HgCl2溶液消毒并用大量蒸馏水洗涤,随后放置在温度35 ℃,湿度50%和光照3 000 lx的PRX-1000A型人工培养箱中进行催芽,待种子萌发后选取发芽一致的种子进行培养。

1.2 盐碱处理

由于现有玉米耐盐碱性评价研究一般采用的胁迫方式是NaCl胁迫或NaCl和Na2CO3混合胁迫[7],胁迫方式较为简单。而实际盐碱地多是中性盐(NaCl、Na2SO4)和碱性盐(Na2CO3、NaHCO3)的复合盐碱地,其pH值较高[8],这种复合盐碱胁迫下玉米的研究报道较少。基于此,本文参考文献[29]的方法,将2种中性盐NaCl、Na2SO4和2种碱性盐NaHCO3、Na2CO3按照1:9:9:1摩尔质量比混合后加入蒸馏水,定容成pH值为9.09±0.05的重度复合盐碱溶液。在试验中证实,在该复合盐碱溶液处理下耐盐碱性不同的玉米可以被有效地区分开来。因此,本研究采用此种复合盐碱溶液对玉米幼苗进行盐碱处理。试验时待2个玉米品种的幼苗长至3片真叶(株高约15 cm)时,将培养皿中的蒸馏水(pH值为7.08)换为复合盐碱溶液对玉米进行盐碱胁迫处理。

1.3 玉米叶片干质量的测量

在盐碱胁迫的不同时间,每个品种各取15株长势均匀的玉米幼苗,分为3组,每组5株,剪下全部叶片部分,用滤纸清理和擦干玉米叶片表面杂质和水分,将其放入样品杯子中置于烘箱内以105 ℃杀青15 min,80 ℃烘干至质量恒定。然后取出样品,冷却至室温,用电子天平分别测量叶片干质量,取每个品种3组叶片干质量的平均值。

1.4 玉米叶片电信号的采集

参照文献[23,27]的方法在盐碱胁迫开始后每天上午10:00测量叶片干质量的同时,分别采集2个玉米品种另外各3株玉米相同叶位的叶片电信号。采集仪器为BL420S生物机能试验系统(成都泰盟科技有限公司生产),该系统具备高输入阻抗(>1010Ω)、高共模抑制比(>120 dB)和低噪声(<1V)、低漂移等特点。研究已经证明,该系统能够满足采集植物叶片电信号的要求[23,27-30]。测试电极为丹麦Ambu公司生产的P-00-S型医用高灵敏度Ag/AgCl心电电极。试验之前对电极进行的测试表明,温度在20~45 ℃范围内变化时,电极采集到的0~50 Hz频段内的信号振幅波动幅度小于0.5%,表明电极的稳定性好[27]。

采集叶片电信号时,1片采集电极贴于玉米叶片正面靠近叶尖位置,另1片电极贴于玉米叶片反面根部位置,电极间距15 cm,参考电极通过导线直接连接至培养槽中放置的铜片上。采集电极通过导电胶与叶片保持良好接触,系统设置的采样频率为2 kHz,开启50 Hz工频抑制[23,27]。同时将被采集的玉米植株和采集系统放置在Faraday笼内屏蔽环境电磁干扰。此外,植物生长和每次采集电信号时的环境条件相同,环境温度为20 ℃,湿度为50%,光照强度为3 000 lx。为了减少对叶片细胞活动的影响,每次信号采集完毕后,及时拆去采集电极。

1.5 玉米叶片电信号边际谱MSE的计算

研究发现,当采集到的玉米叶片电信号时域波形的数据时长在200 s以上时,信号的复杂度是稳定的[27],因此,本文在采集到的叶片电信号时域波形的数据中,取数据时长为200 s的信号进行HHT变换,得到盐碱胁迫过程中2个玉米品种各3个处理组叶片电信号的希尔伯特谱,再由希尔伯特谱得到边际谱,然后分别计算各边际谱的相对谱熵MSE,分别取2个品种各3个处理组的平均值进行动态分析。

式中为()的序列长度。

1.6 玉米叶片电信号相应指数RI的计算

在盐碱胁迫下,玉米叶片电信号MSE将发生改变,其变化程度可以通过基于边际谱熵的电信号响应指数RI(response index)来表征

式中MSE0为胁迫发生前的边际谱熵,MSE为胁迫过程中的边际谱熵。

1.7 玉米叶片MDA的测量

在上述采集玉米叶片电信号的同时,测量盐碱胁迫过程中其他玉米植株相同叶位的叶片中MDA(Malondialdehyde)含量,MDA含量的测量方法见参考文献[31]。将叶片先用滤纸吸干表面培养液,然后放入电子天平称量鲜质量并记录。将样品剪碎后,加入2 mL预冷的5%三氯乙酸,加入少量石英砂,在经过冰浴的研钵内研磨至匀浆,转移到5 mL刻度离心试管,将研钵用缓冲液洗净,清洗液移入离心管中,用5%三氯乙酸定容至5 mL,4 000 r/min下离心10 min,吸取上清液2 mL,加入0.67%硫代巴比妥酸的10%三氯乙酸溶液3 mL,于沸水浴中加热30 min,迅速冷却,再于4 000 r/min离心机中离心10 min,取上清液,以蒸馏水为空白调透光率,测定450、532、600 nm波长下的吸光度,按照下式计算MDA的浓度

(mol/L)=6.45(532-600)-0.56450(4)

再根据叶片鲜质量计算测定样品中MDA的含量

每次试验重复3次,取平均值。

1.8 统计分析

各测量结果均用平均值±标准差表示,差异显著性采用SPSS软件进行分析,<0.05表示差异到达显著水平,<0.01表示差异达到极显著水平。数值拟合采用origin软件进行。

2 结果与分析

2.1 盐碱胁迫对2个玉米品种幼苗叶片干质量的影响

叶片是植物进行物质累积的主要场所,叶片干质量是叶片物质生产量的最终体现。叶片干质量的变化是植物叶片对盐碱胁迫的综合反映,也是判断植物耐盐碱性强弱最可靠的指标[7,32]。为了确定试验的2个玉米品种耐盐碱性的强弱,首先测量了盐碱胁迫下郑单958和名玉20玉米品种叶片干质量变化的差异,结果见图1。由图1可见,在盐碱胁迫过程中郑单958品种叶片干质量的增长缓慢,在胁迫4 d时干质量反而有所下降;而名玉20品种的叶片干质量则一直明显增长,在胁迫4 d时干质量才停止增长,此后保证基本不变的趋势。在表观上,在胁迫3 d时郑单958品种的叶片开始卷曲,叶色变黄,名玉20品种的叶片形态和叶色变化不明显。结果表明:盐碱胁迫抑制了郑单958品种叶片物质的积累(<0.01),对名玉20品种物质积累的影响相对较小。由此可见郑单958品种的耐盐碱性较差,这个结论与文献报道是一致的[9]。

图1 盐碱胁迫对玉米幼苗叶片干质量的影响

2.2 盐碱胁迫下玉米叶片电信号的时域波形

图2和图3分别为电极采集到的盐碱胁迫下郑单958和名玉20玉米各3株相同叶位的叶片电信号平均值的时域波形,其具有非平稳和随机的特征。在正常情况下(未胁迫时),振幅波动的幅度在1 000~2 000V以内,与以往报道的结果是一致的[23,27,30]。盐碱胁迫对玉米叶片电信号有明显影响,随着胁迫时间的延长,叶片电信号的振幅呈现出减小的趋势;在胁迫第5天时,郑单958玉米叶片电信号的振幅降至20V以内,已经被噪声所湮没;与此对应,名玉20品种还存在振幅在100V以内的微弱电信号。图2和图3中测量开始后电信号出现的渐变过程,可能是采集电极贴附在叶片上时细胞的适应过程。

图2 盐碱胁迫下郑单958玉米叶片电信号时域波形

图3 盐碱胁迫下名玉20玉米叶片电信号的时域波形

2.3 盐碱胁迫下玉米叶片电信号MSE的变化

电极采集到的玉米叶片电信号是一种微弱和非稳定的随机信号,HHT方法特别适合于这种信号的信息提取[27,33]。基于HHT方法分别计算出2个玉米品种叶片电信号的边际谱如图4和图5所示。貌似无序的玉米叶片电信号的边际谱具有连续的特征,经历不同时间的盐碱胁迫,边际谱的复杂度发生了变化。

图4 盐碱胁迫下郑单958玉米叶片电信号边际谱

图5 盐碱胁迫下名玉20玉米叶片电信号的边际谱

边际谱的复杂度通过边际谱熵MSE来描述,边际谱越狭窄,MSE越小,表示信号中存在明显的振荡节律,复杂度小;反之,边际谱越平坦,MSE越大,表明信号的复杂程度越高[27]。根据图4和图5计算得到的盐碱胁迫下郑单958和名玉20玉米叶片电信号边际谱熵MSE的变化如图6a所示。由图6a可见,郑单958玉米叶片正常生长时的MSE在0.53附近,在盐碱胁迫过程中MSE出现了单调下降的趋势,在胁迫3、4和5 d时,MSE分别下降了39.3%、48.9%和51.2%。与此相对应,在盐碱胁迫过程中,名玉20品种的MSE呈现出波动的变化,在胁迫4 d时,MSE才开始迅速下降,说明此时名玉20品种叶片细胞膜的结构才发生了不可逆的变化。

图6 盐碱胁迫下2种玉米品种叶片电信号边际谱熵MSE和丙二醛MDA含量的变化

2.4 盐碱胁迫下2个玉米品种叶片MDA含量的变化

为了说明玉米叶片电信号边际谱MSE变化的生物学意义,本文在盐碱胁迫的不同时间采集玉米叶片电信号的同时,对比研究了同批次复合盐碱胁迫处理的2个玉米品种相同叶位的叶片中MDA含量的变化,如图6 b所示。研究MDA的原因在于MDA含量常作为植物细胞膜受损的主要指示物,通过MDA含量的变化可以了解细胞膜脂过氧化的程度,进而对膜系统受损程度进行评价[34-35]。在植物耐盐碱性的研究中,MDA作为最重要的生化评价指标,被广泛的采用[8,36]。由图6b可见,在复合盐碱胁迫2 d时,郑单958品种的叶片MDA含量开始迅速上升,在胁迫3、4和5 d时MDA的相对增长率分别为72.7%、125.8%和143.8%,差异均达到了极显著的水平(<0.01),MDA的这种变化趋势与一些有关盐胁迫的研究报道是类似的[37-39]。与此相对应,在胁迫1~4 d期间,名玉20品种的叶片中MDA含量变化不大,从4d开始才显著升高,在胁迫5 d时相对增长率达到了114.0%,差异达到了极显著的水平(<0.01)。

比较图6a和图6b可知,郑单958和名玉20品种的MSE和MDA之间可能具有一定的相关性,拟合结果如图7所示。

图7 盐碱胁迫下2种玉米品种叶片边际谱熵MSE和丙二醛MDA的相关性

2.5 盐碱胁迫下2个玉米品种叶片电信号响应指数RI的变化

由于在相同的盐碱胁迫过程中,耐盐碱性不同的郑单958和名玉20叶片电信号MSE的变化程度有所差异。为了定量表示MSE的变化程度,本文定义了基于MSE的叶片电信号响应指数RI。RI越大表明叶片电信号MSE的变化越大,即叶片电信号边际谱的复杂程度变化越大。盐碱胁迫过程中郑单958和名玉20品种的RI值如图8所示。在相同的盐碱胁迫条件下,耐盐碱性较弱的郑单958品种的RI值在胁迫开始后就呈现出单调上升的趋势,在胁迫2 d后迅速增大,而耐盐碱性较强的名玉20品种的RI值在胁迫第4 d以后才开始明显增大,从胁迫2 d开始,郑单958的RI值就一直明显高于名玉20。在胁迫2、3和4 d时郑单958的RI值分别比名玉20的RI值相对增长了42%、193%和332%,差异十分显著。

图8 盐碱胁迫下2个玉米品种电信号响应指数RI的变化

3 讨 论

植物电信号的来源非常复杂,包括系统电位(system potential,SP)、动作电位(action potential, AP)和变异电位(variation potential, VP),AP与细胞膜上Ca2+、Cl-和K+等离子通道的活性有关,VP与细胞膜上H+泵的失活有关,SP与H+泵的激活有关[40]。本文的研究发现,在正常的生理状态下(胁迫开始时),叶片电信号的MSE数值相对最大,表明叶片细胞生理电活动的复杂度较高;在盐碱胁迫下,MSE表现出下降的趋势。由于在盐碱胁迫过程中,植物首先遭遇渗透胁迫和离子毒害[4,41],碱胁迫下pH 的升高会进一步破坏细胞的离子吸收[42],使根系细胞膜的H+泵失活和K+等离子通道活性变化,离子外流增强[43-44],其结果导致根系细胞膜上的SP发生变化、并诱发AP产生[45-47]。当AP传递到叶片时叶片细胞膜上的H+泵将受到抑制,导致叶片电信号中SP信号的振幅和复杂度减少,影响叶片细胞的光合作用[22]、呼吸作用[48-49]和ATP含量产生[50]等重要的生理过程。因此,盐碱胁迫下叶片细胞膜上离子跨膜运输的抑制可能是叶片电信号MSE减小的原因。在盐碱胁迫的持续进行下,叶片细胞膜会发生严重损伤,造成细胞膜上各种离子通道的破坏和离子泵的瓦解,大量电解质外渗[51],结果使叶片电信号的节律性大为增强,MSE进一步减小。由此看来,盐碱胁迫下植物叶片电信号MSE发生变化意味着叶片细胞膜上的离子运输受到了影响,而MSE的快速下降则表明细胞膜受到了损伤。由于MSE的变化发生在细胞功能状态变化之前,采集电极所涵盖的任何一个细胞生理电活动的变化都会导致叶片电信号MSE的变化,因此,依据MSE的变化判断叶片细胞功能状态的变化具有早期和灵敏的特点;又由于贴片电极是将表面电极直接贴附在植物叶片上活体测量,不会对植物造成伤害,所以还具有在位和无损伤的优点。

本研究发现,盐碱胁迫下耐盐碱性不同的郑单958和名玉20品种叶片电信号MSE和丙二醛MDA的变化规律不同。由于2个玉米品种叶片中MDA含量的变化与MSE的变化呈现负相关,说明盐碱胁迫造成的叶片细胞膜脂过氧化可能是MSE下降的原因。

基于盐碱胁迫下耐盐碱性不同的2个玉米品种MSE的变化程度不同,本文定义了电信号响应指数RI,用于表征MSE的变化程度。RI值越大,表明叶片细胞受到的伤害越大,耐盐碱性越差。因此,依据RI的大小可以对盐碱胁迫下不同品种的植物叶片细胞伤害的影响程度进行定量诊断,进而对耐盐碱性强弱做出评价。在本文中,相同的盐碱胁迫下耐盐碱性不同的2个玉米品种的RI值差异明显,根据这种差异可以方便的确定出玉米耐盐碱性的强弱。将RI作为评价指标的优点在于RI值始终处于0和1之间,与作物种类和品种无关,是统一的量化标准,易于计算机定量分析与自动评判。

应该指出,本文中电信号是在植物叶片上无损和在位采集的,MSE和RI的数值大小反映的是盐碱胁迫下叶片细胞群离子运输和细胞膜发生的变化,评价指标RI值与物种无关,因此,本文提出的评价植物耐盐碱性的方法不但具有早期、灵敏和无损伤的特点,同时还具有普适性。

4 结 论

1)在pH值为9.09的复合盐碱溶液胁迫过程中,耐盐碱性较差的郑单958品种叶片电信号MSE(marginal spectrum entropy)表现出不断下降的趋势,在胁迫3、4和5 d时,MSE分别下降了39.3%、48.9%和51.2%。耐盐碱性较强的名玉20品种的MSE呈现出波动的变化,表明盐碱胁迫下郑单958品种叶片细胞的离子跨膜运输被抑制,名玉20品种的叶片细胞内存在复杂的代谢调节,以维持叶片细胞离子运输的动态平衡和正常的功能状态。

2)在复合盐碱胁迫2 d时,郑单958品种的叶片MDA(malondialdehyde)含量迅速上升,在胁迫3、4和5 d时MDA的相对增长率分别为72.7%、125.8%和143.8%,名玉20品种的MDA含量在胁迫4 d后才开始明显上升,表明郑单958品种在胁迫初期就出现了膜脂过氧化现象,随着胁迫过程的进行,膜脂过氧化现象越来越严重,名玉20品种在胁迫4 d以后才发生显著的膜脂过氧化现象,盐碱胁迫造成的叶片细胞膜脂过氧化可能是叶片电信号MSE下降的原因。

3)从盐碱胁迫2 d开始,郑单958玉米品种叶片电信号响应指数RI(response index)的数值一直显著高于名玉20。在胁迫2、3和4 d时郑单958的RI值分别比名玉20的RI值相对增长了42%、193%和332%,根据RI值的大小可以对盐碱胁迫下玉米叶片细胞离子运输和细胞膜伤害的影响程度进行灵敏和早期的定量诊断,进而实现对玉米幼苗耐盐碱性强弱的在位和无损伤的评价。

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Nondestructive evaluation method for saline-alkaline tolerance of maize based on marginal spectral entropy of electric signal in leaf

Liu Kai1, Zhao Yanyan2, Xi Gang1※, Yang Yunjing3, Du Guangyuan3

(1.,’710054,; 2.,,451100,; 3.,712100,)

Saline-alkaline stress (SAS) is one of the major abiotic stresses affecting the growth of plants. It has been a severe problem that restricts plant production and even the development of the ecological environment. The improvement of plant saline-alkaline tolerance and selection of saline-alkaline tolerance plant varieties are becoming hot spots for research. To develop and select saline-alkaline tolerance plants, an evaluation method that can accurately judge the plant saline-alkaline tolerance must be first established. In the present study, the evaluation of saline-alkaline tolerance of plants is generally based on morphological indicators and physiological and biochemical indicators. These evaluation methods require a large number of samples and long cycle, and cannot be early diagnosed. Moreover, many of the indicators must be obtained through the destructive measurement of test-tube experiments, which are not nondestructive testing. Therefore, the traditional evaluation method has many disadvantages. In order to explore the methods of early, sensitive, in situ and nondestructive testing saline-alkaline tolerance of plants, a complex solution consisting of NaCl, Na2SO4, NaHCO3and Na2CO3with pH value of 9.09 was used to stress 2 kinds of maize variety seedlings of Zhengdan 958 with poor saline-alkaline tolerance and Mingyu 20 with strong saline-alkaline tolerance. Time-domain waveforms of leaf electrical signals of Zhengdan 958 and Mingyu 20 seedlings during saline-alkaline stress were collected. The marginal spectra of 2 kinds of maize leaf electrical signals were obtained by Hilbert-Huang transformation (HHT). The changes of marginal spectrum entropy (MSE) of maize leaf electrical signals and the biological significance were analyzed. The results showed that the MSE of leaf electrical signals from maize variety Zhengdan 958 continued to decline in the process of saline-alkaline stress, while the MSE of leaf electrical signals from maize variety Mingyu 20 changed in volatility. It was indicated that the ion transport of leaf cells in Zhengdan 958 was inhibited under saline-alkaline stress, and there was complex metabolic regulation in leaf cells of Mingyu 20 to maintain the dynamic balance of ion transport and normal functional status of leaf cell. The study also found that the malondialdehyde (MDA) content in leaf of Zhengdan 958 was increasing in the process of saline-alkaline stress, and the MDA content in leaves of Mingyu 20 began to increase significantly after 4 days of stress. This phenomenon suggested that there was membrane lipid peroxidation in leaves of Zhengdan 958 in the early stages of saline-alkaline stress, and it was more and more serious with the process of the stress, however, there was significant membrane lipid peroxidation in leaves of Mingyu 20 after 4 days of stress. The membrane lipid peroxidation of leaf cells caused by saline-alkaline stress could be the reason to the decrease of MSE about maize leaf electrical signals. Due to that the variation of the MSE from 2 maize varieties with different saline-alkaline tolerance under saline-alkaline stress was different, the response index (RI) of electrical signal based on the MSE was defined in this paper. The results showed that the RI values of maize varieties Zhengdan 958 and Mingyu 20 were obviously different in the processes of saline-alkaline stress. The influence of saline-alkaline stress on the ion transport and cell membrane injury of maize leaf cell could be sensitive and early quantitatively diagnosed according to the size of RI, and then to achieve in situ measurement and nondestructive evaluating saline-alkaline tolerance of maize seedlings. Since the RI based on plant electrical signals has not relationship with the species, the method proposed in this paper to evaluate the saline-alkaline tolerance of maize seedlings may also have a wide range of applicability. It is expected that the evaluation method about saline-alkaline tolerance of plant proposed in this paper can be verified through a large number of experiments.

stresses; crops; nondestructive testing; maize; saline-alkaline stress; electrical signal; marginal spectrum entropy; evaluation

10.11975/j.issn.1002-6819.2018.02.027

Q64

A

1002-6819(2018)-02-0197-08

2017-09-08

2018-01-08

国家自然科学基金资助项目(31471412,51277151);陕西省教育厅科学研究计划项目(15JK1515)

刘锴,讲师,博士,主要从事生物光电信息的分析与应用研究。Email:leaukai@gmail.com

习 岗,陕西杨凌人,教授,研究方向为生物光电信息的分析与应用。Email:xig@xaut.edu.cn

刘 锴,赵燕燕,习 岗,杨运经,杜光源. 基于叶片电信号边际谱熵的玉米耐盐碱性无损评价方法[J]. 农业工程学报,2018,34(2):197-204. doi:10.11975/j.issn.1002-6819.2018.02.027 http://www.tcsae.org

Liu Kai, Zhao Yanyan, Xi Gang, Yang Yunjing, Du Guangyuan. Nondestructive evaluation method for saline-alkaline tolerance of maize based on marginal spectral entropy of electric signal in leaf[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(2): 197-204. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2018.02.027 http://www.tcsae.org

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