淹水弱光复合胁迫对夏玉米根形态结构、生理特性和产量的影响

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王群^,, 赵向阳, 刘东尧, 闫振华, 李鸿萍, 董朋飞, 李潮海河南农业大学农学院/省部共建小麦玉米作物学国家重点实验室,郑州 450046

Root Morphological, Physiological Traits and Yield of Maize Under Waterlogging and Low Light Stress

WANG Qun^,, ZHAO XiangYang, LIU DongYao, YAN ZhenHua, LI HongPing, DONG PengFei, LI ChaohaiCollege of Agronomy, Henan Agricultural University/National Key Laboratory of Wheat and Maize Crop Science, Zhengzhou 450046

责任编辑: 杨鑫浩
收稿日期:2020-03-16接受日期:2020-06-9网络出版日期:2020-09-01

基金资助:

现代农业产业技术体系专项资金.CARS-02-17
国家重点研发计划“粮食丰产增效科技创新”重点专项.2017YFD0300300
国家公益性行业.农业科研专项201503117

Received:2020-03-16Accepted:2020-06-9Online:2020-09-01
作者简介 About authors
王群,E-mail：wangqun177@163.com

摘要
【目的】随着全球气候变化,玉米生长季气象灾害频发,阴雨寡照已成为黄淮南部地区玉米的主要非生物灾害之一。本研究通过比较2个敏感性不同玉米品种在花期淹水弱光复合胁迫的根系生长动态、结构特征和生理特性,以期探明玉米根系对花期阴雨寡照胁迫的响应特征。【方法】以郑单958和豫玉22为材料,设对照（CK）、淹水（W）、弱光（S）、淹水+弱光（WS）4个不同胁迫处理,采用盆栽试验比较不同胁迫处理下玉米根干重、长度、根表面积、根体积、节根层数的动态变化特征,探明根形态结构、根生理指标及产量对淹水、弱光及复合胁迫的响应特征。【结果】淹水、弱光及其复合胁迫下玉米根总干重、根总长度、根表面积和根体积均显著下降,3种逆境以淹水弱光复合胁迫降幅最大,其次是淹水、弱光单一胁迫,W、S、WS处理的单株根干重和根长度平均比CK降低15.21%、5.08%、21.07%和14.86%、5.52%、18.14%,根表面积和根体积则比CK平均降低9.83%、4.62%、12.72%和12.62%、6.61%、16.23%;WS处理的根干重、根长度、根表面积和根体积比W处理平均降低6.64%、3.84%、3.21%和4.12%,比S处理平均降低16.55%、13.10%、8.41%和10.32%,且WS与S处理间差异显著,与W处理之间差异不显著。淹水及复合胁迫下根通气组织发达,根气腔数量、面积、孔积率和节根层数明显增加,其中W、WS处理根单位面积上气腔数量比CK平均增加5.29和10.03倍,气腔面积较CK平均增加5.76和13.27倍,根孔积率较CK平均增加8.01和10.00倍,W和WS处理节根层数平均比CK增加1—2层,但S处理与CK无差异。淹水、弱光及复合胁迫使玉米根系生理指标和产量显著降低,尤其以复合胁迫下降幅度最大,各指标处理间变化趋势为WS<W<S<CK;逆境处理期间2个品种WS处理的根活力、根总吸收面积、活跃吸收面积和活跃吸收比CK平均降低52.82%、28.48%、36.72%和20.00%,玉米产量比CK平均下降24.52%,差异显著。随淹水、弱光时间延长,根形态和根生理指标降幅越大,而根通气组织数量、面积和孔积率则增幅越大,花期处理5—7 d是根系生长忍受淹水弱光胁迫的阈值。不同品种对淹水、弱光及复合胁迫的响应程度不同,钝感型品种（郑单958）在淹水弱光胁迫下根干重、根长度、根活力、根吸收面积等指标下降幅度小于敏感型品种（豫玉22）,其中郑单958的W、WS、S处理根干重和根活力比CK平均降低13.71%、4.39%、16.28%和31.95%、9.99%、51.45%,而豫玉22降幅则分别为16.71%、5.78%、25.85%和43.83%、13.44%、51.19%,且郑单958根系适应胁迫5 d后表现出恢复性生长,而豫玉22则部分指标持续下降。2个品种在淹水弱光胁迫后根结构的变化亦表现不同,郑单958根系形成的融生型气腔规则,腔壁完整,细胞排列整齐,而豫玉22根系气腔不规则,腔壁部分断裂,部分薄壁细胞裂解;郑单958根气腔面积、数量和孔积率的增加幅度远大于豫玉22,且郑单958节根层数比豫玉22增加1—2层,表现出根系更强的逆境适应性和补偿性;郑单958产量降幅小于豫玉22,其中郑单958的W、S和WS处理比CK降低17.66%、13.30%、23.47%,而豫玉22产量比CK则分别降低20.86%、14.14%、25.53%。【结论】花期淹水、弱光胁迫严重限制根系生长发育、生理特征及产量,复合胁迫的效应远大于单一胁迫,淹水胁迫效应大于弱光胁迫;根系生长花期胁迫的阈值为5—7 d,根系通过增加节根层数、改变根结构、增加气腔数量和扩大气腔面积应对逆境胁迫,并且对逆境胁迫具有主动的自调节效应和适应性生长。
关键词： 夏玉米;淹水弱光复合胁迫;根结构;根活力;根吸收和活跃吸收面积;产量

Abstract

【Objective】With the global climate change, meteorological disasters occur frequently during the maize growth season. In order to explore characteristics of root response to rainy and low light stress, this study was carried out to investigate root morphology, physiological traits and yield of maize under waterlogging and low light combined stress at flowering stage.【Method】Taking two different maize varieties (Zhengdan958 and Yuyu22) as research objects, the experiment, including four treatments with contrast (CK), waterlogging (W), low light (S), and waterlogging and low light (WS) was conducted to compare dynamic changes of root dry weight, root length, root surface area, root volume, nodal root layer and to analyze the morphological, anatomical and physiological characteristics and yield under different stress.【Result】The root dry weight, root length, root surface area and root volume of maize were significantly decreased under combined stress, and these indicators were the largest reductions under waterlogging and low light stress, the second reductions under waterlogging stress and the smallest reductions under low light stress. Compared to CK, root dry weight were decreased by 15.21%, 5.08%, 21.07% , and root length were decreased by 14.86%, 5.52%, 18.14% in average under waterlogging stress, low light stress and combined stress, respectively. Root superficial area and root volume were decreased by 9.83%, 4.62%, 12.72% and 12.62%, 6.61%, 16.23% under three different stress (W, S, and WS). Compared to W and S stress, root dry weight, root length, root surface area and root volume were decreased by 6.64%, 3.84%, 3.21%, 4.12% and 16.55%, 13.10%, 8.41%, 10.32% under WS stress, and it was significantly different between WS and S. But there was no obviously different between WS and W. Root aerenchyma numbers, root aerenchyma areas, root porosity and crown root layers were increased significantly under waterlogging stress as well as waterlogging and low light combined stress. Compared with the contrast, root aerenchyma numbers were increased significantly by 5.29 and 10.03 times with W and WS treatment in average, respectively. Then aerenchyma areas and root porosities were increased by 5.76, 13.27 times and 8.01, 10.00 times under W and WS treatment, respectively. Crown root layers had more 1 to 2 layers under W and WS than that under CK, however, there was not different obviously between S and CK. Root physiological traits and yield of maize were decreasing significantly under waterlogging and low light stress. Especially there was the largest decreasing under combined stress. Compared with CK, root activities, total root absorbing area, root active absorbing area and ratio of active root absorption of maize were decreased significantly by 52.82%, 28.48%, 36.72% and 20.00% in average under combined stress, respectively. The change order of treatments was WS<W<S<CK. The yield of maize was significantly decreased by 24.52% under combined stress in two maize varieties. With the extension of stress days, root morphology and physiological traits were more and more decreasing under waterlogging and low light stress. But aerenchyma numbers, root aerenchyma areas, root porosity were much more increasing with extension of stress days, the longer the stress days, the greater the increasing. The threshold of root growth was 5-7 d under waterlogging and low light combined stress. It had different responses to waterlogging, low light and combined stress between two maize varieties. The decreasing degree of root dry weight, root length, root activity and root absorption area was much less in insensitive cultivars (Zhengdan 958) than in sensitive cultivars (Yuyu 22) under waterlogging and low light stress. The root dry weight and root activities were decreased by 13.71%, 4.39%, 16.28% and 31.95%, 9.99%, 51.45% in Zhengdan 958 varieties under waterlogging stress, low light stress, and combined stress, respectively, but these parameters were decreased by 16.71%, 5.78%, 25.85% and 43.83%, 13.44%, 51.19% in Yuyu22 varieties under the same stress, respectively. In addition, root growth in Zhengdan 958 showed restorative growth after 5 stress days, while it showed a continuous declination in Yuyu 22 varieties after 5 stress days. There was a different change of root anatomy with different maize varieties. Under stress arenchyma shape was regular and cell wall was integrated orderly in Zhengdan958, but aerenchyma was irregular, and cell wall was ruptured partially in Yuyu 22. In addition, aerenchyma numbers, root aerenchyma areas and root porosity were much more increasing degree in Zhengdan958 than those in Yuyu 22. Under waterlogging and combined stress, maize root layer number were increased by 1 to 2 layers in Zhengdan958 than that in Yuyu22, and it showed Zhengdan958 was much stronger adaptable and compensatory growth. Yield of Zhengdan958 was much higher than that of Yuyu22. Compared with CK, the maize yield was decreased by 17.66%, 13.30%, and 23.47% of Zhengdan 958 under waterlogging stress, low light stress and combined stress, respectively; At the same time, the yield was decreased by 20.86%, 14.14%, and 25.53% in Yuyu 22. With the prolongation of stress days, the decreasing in Yuyu22 was greater than in Zhengdan958. 【Conclusion】The root growth and development, physiological characteristics and yield were restricted severely by the waterlogging and low light stress at flowering stage. The effect of combined stress was much larger than that of single stress, and the effect of waterlogging stress was much larger than that of low light stress. The threshold value of root growth enduring stress was 5 to 7 days at flowering stage of maize, and the maize roots had positive response and compensatory growth to abiotic stress.

Keywords：summer maize;waterlogging and low light stress;root morphology and anatomy;root activities;root absorbing and active absorbing areas;yield

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本文引用格式
王群, 赵向阳, 刘东尧, 闫振华, 李鸿萍, 董朋飞, 李潮海. 淹水弱光复合胁迫对夏玉米根形态结构、生理特性和产量的影响[J]. 中国农业科学, 2020, 53(17): 3479-3495 doi:10.3864/j.issn.0578-1752.2020.17.006
WANG Qun, ZHAO XiangYang, LIU DongYao, YAN ZhenHua, LI HongPing, DONG PengFei, LI Chaohai. Root Morphological, Physiological Traits and Yield of Maize Under Waterlogging and Low Light Stress[J]. Scientia Acricultura Sinica, 2020, 53(17): 3479-3495 doi:10.3864/j.issn.0578-1752.2020.17.006

0 引言

【研究意义】玉米是我国重要粮食作物之一,近10多年发展迅速,已成为我国第一大作物^[1]。黄淮平原是我国玉米优势产区,其播种面积占全国总面积的三分之一以上^[2]。该区光热水资源较为充沛,但时空分布不均,灾害天气较多,夏玉米生长季易遭受干旱、涝渍、弱光和高温等不良天气影响,尤其是玉米花期遭受阴雨、涝害或二者叠加等灾害的影响,导致夏玉米产量低且不稳定。据统计全球每年有10%—16%的耕地遭受渍涝灾害,且未来渍涝灾害发生的频率和强度将逐渐增加^[3,4,5,6];随着全球气候变化,中国长江流域、黄淮海区域阴雨灾害发生频率亦呈增加趋势^[7],阴雨寡照已成为影响该区玉米稳产的主要非生物灾害之一。根系作为作物感应水分（洪涝、干旱）灾害的先锋器官,不仅承担着吸收水分、养分的重要功能,而且对作物地上部生长和产量形成至关重要,因此研究阴雨寡照下玉米根系生长分布、结构特点和生理响应特征,对指导玉米生产抗逆减灾具有重要意义。【前人研究进展】阴雨寡照实质是阴（即弱光）和雨（即淹水）2种胁迫的综合体现,前人研究表明,淹水胁迫易造成土壤氧气含量急剧降低,根干重、根长度、根表面积和体积迅速下降^[8,9,10],而根系通过形成融生气腔或通气组织来适应淹水胁迫^[11,12,13]。淹水不仅影响根系形态结构,也影响其生理功能,淹水使根系活力、吸收活力下降,乳酸脱氢酶、乙醇脱氢酶、乙醛脱氢酶、丙酮酸脱氢酶等无氧呼吸酶活性增强,无氧代谢产物（乙醇、乙醛和乳酸等）累积^[14,15],恶化了根细胞环境,加速了根系衰老和死亡,亦阻碍地上部物质生产和运输,主要表现为干物质积累量锐减,籽粒百粒重和穗粒数减少,果穗长和果穗粗下降,产量显著降低^[16,17,18]。弱光对作物的影响主要通过影响叶片的大小和功能,如弱光使绿叶叶面积减小,叶绿素含量、光合速率降低,玉米雌雄间差增大,花粉和花丝活力下降,导致籽粒败育率增加、产量下降^[19,20];弱光胁迫下叶片活性氧、MDA含量增加,抗氧化保护酶（SOD、POD、CAT）活性升高,叶片衰老加剧^[21]。弱光不仅影响叶片生长和生理功能,也使根系干重、根长密度、根直径等降低^[22,23],根系活力、根总吸收面积、活跃吸收面积等参数降低,导致玉米根系吸收功能减弱^[24,25]。【本研究切入点】过去大量报道多集中于淹水或弱光单一胁迫对玉米生长发育和生理功能的影响,且以苗期胁迫研究较多,然而实际农业生产中阴和雨（渍涝和弱光）常常相伴而生,尤其以玉米花期弱光对产量影响最大^[26],但对玉米花期淹水弱光复合胁迫如何影响玉米根系形态和结构特征、生理特性以及产量和产量形成的研究报道较少。【拟解决的关键问题】本文通过田间盆栽试验,采用人工控制模拟逆境胁迫环境,研究花期淹水弱光复合胁迫对玉米根系形态、结构和生理功能及产量的影响,为丰富玉米逆境生理理论和生产上采取缓解阴雨寡照灾害有效栽培措施提供理论依据。

1 材料与方法

1.1 试验设计与材料

试验于2017—2018年在河南农业大学科教园区进行。采用盆栽试验,设置4个处理,分别为对照（CK,自然光）,淹水（W）,弱光（S）,淹水+弱光（WS）,重复3次。在玉米刚开始抽雄（即雄穗刚可见）时进行胁迫处理,其中弱光处理采用透光率为50%的遮阳网从顶部遮阴,遮阳网距离地面高度为5 m,以保持遮阴棚内小气候与对照条件基本一致;淹水处理是通过定时补充灌水始终保持土壤处于淹水状态,水面高出盆中土壤表面3—5 cm;淹水弱光复合胁迫是顶部采用透光率为50%的遮阳网进行遮阴,网距地面高度为5 m,同时通过定时补充灌水盆内土壤处于淹水状态,水面保持3—5 cm。处理期间定期测定田间小气候（光照、温度、湿度）,各胁迫处理持续天数为9 d,分别在处理的第1天、第3天、第5天、第7天、第9天进行取样和指标测定,每次取样3株。

试验供试品种为郑单958（ZD958）和豫玉22 （YY22）,其中郑单958对寡照不敏感,豫玉22对寡照敏感^[26],郑单958的种植密度为67 500 株/hm²,豫玉22的种植密度为45 000 株/hm²,2个品种均保持株距32 cm,通过调整种植的行距调整种植密度,郑单958品种种植行距为46.3 cm,豫玉22品种种植行距69.5 cm。试验盆体高35 cm,上口径32 cm,下口径27 cm,将耕层土壤过筛混匀后装盆,每盆装土15 kg,供试土壤为潮土,有机质含量为8.17 g·kg^-1、碱解氮为60.21 mg·kg^-1,速效磷为20.41 mg·kg^-1、速效钾为129.11 mg·kg^-1,2年均于6月10号播种,10月1号收获,成熟时留6株玉米植株进行考种计产。

1.2 测定项目与方法

1.2.1 田间小气候记录用多台温湿度记录仪（BR-WS20）记录各处理期田间小气候（温度、湿度和光照强度）的日变化,每60 min记录一次,结果如图1所示。

图1

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图1处理期间田间小气候

CK：对照,W：淹水,S：弱光,WS：淹水+弱光。下同
Fig. 1Field microclimate during stress time

CK: Contrast, W: Waterlogging, S: Low light, WS: Waterlogging and low light. The same as below

1.2.2 根系形态指标分别在胁迫处理的第1天、第3天、第5天、第7天、第9天取各处理生长一致的玉米3株,用缓速水流反复冲洗玉米根部,冲洗干净后,将不同层次的节根完整剪下,采用根系扫描仪EPSON Expression 11000XL 扫描不同层次的节根,用软件WinRHIZO 分析并计算根长度、根表面积、根体积、节根层数;将根系在105℃下杀青30 min,75℃烘干至恒重^[27],并称重。

1.2.3 根系结构观察分别在胁迫处理的第3天、第9天取各处理同一根层相同部位的根,截取距离根尖1 cm左右的根段为材料,用FAA固定液（福尔马林﹕冰醋酸﹕70%酒精混合液（体积比）=15﹕15﹕70）处理、固定和保存根段^[28],做石蜡切片,在OLYMPUS BX43显微镜下对根系切片进行拍照、观察和数据统计。

1.2.4 根通气组织数量、面积和孔积率测量和计算在胁迫处理的第1天、第3天、第5天、第7天、第9天取同一层次根系,做显微切片,并采用软件Cell Sens Standard分析显微镜下拍摄的根切片,记录气腔数量、气腔面积、根横截面积,并根据下列公式计算孔积率^[8],根孔积率=（根气腔面积/根横切面积）×100%。

1.2.5 根系活力在胁迫处理的第1天、第3天、第5天、第7天、第9天分别取处理后2 cm长的根尖,用蒸馏水冲洗干净,吸水纸擦净根表面水分,用改良TTC法测定根系活力^[29]。

1.2.6 根系吸收和活跃吸收面积在胁迫处理的第1天、第3天、第5天、第7天、第9天分别取生长一致的植株,用缓速水流冲洗干净玉米根系,采用甲烯蓝蘸根法测定单株完整根系总吸收面积和活跃吸收面积,并根据公式计算活跃吸收比,根活跃吸收比=（活跃吸收面积/总吸收面积）×100%^[30]。

1.2.7 籽粒产量在不同胁迫处理的第1天、第3天、第5天、第7天、第9天胁迫结束后,转入正常生长条件下继续生长,直至玉米完全成熟,取6株进行收获果穗,并脱粒,在75℃下烘干至恒重称重。

1.3 统计与分析

试验数据取2年的平均值,数据采用Excel 2007处理,采用SPSS软件进行方差分析,采用SigmaPlot12.5软件进行作图。

2 结果

2.1 淹水弱光复合胁迫对玉米根形态特性的影响

2.1.1 对根总干重的影响由图2可以看出,随着处理时间延长,CK和S处理根干重呈增长趋势,W和WS处理根干重呈下降趋势。淹水、弱光及复合胁迫均显著降低了玉米根总干重,处理间根干重的变化趋势表现为CK>S>W>WS,其中在胁迫9 d内S、W和WS处理较CK降幅分别为1.62%—9.31%、3.22%—23.62%和5.62%—28.54%,表现为复合胁迫对根干重影响最大,其次是淹水、弱光胁迫。随着胁迫天数的延长,根干重降幅增大,如WS处理3 d根干重比CK降低16.00%,而胁迫9 d比对照降低24.87%。2个品种比较,以豫玉22品种对淹水和复合胁迫更敏感,其中WS、W和S处理的根干重比CK平均降低25.31%、15.96%和5.48%,而郑单958的WS、W和S处理比CK平均降低15.96%、13.47%和4.33%。2个品种随着胁迫天数增加,根干重降幅和降低幅度趋势不同,郑单958在胁迫第5天时根干重降为最低值,WS、W和S处理比CK分别降低28.54%、23.62%和9.31%,随后根干重趋于增加,而豫玉22在处理第7天降为最低值,WS、W和S处理比CK降低34.42%、25.65%和10.50%,且根干重持续减少,处理间差异显著。2个品种对胁迫类型的反应基本一致,均以WS处理下降幅度最大,且豫玉22降低幅度大于郑单958,其中WS处理比CK分别下降10.00%—34.42%（豫玉22）和1.81%—26.22%（郑单958）,其次是淹水胁迫,豫玉22的下降幅度为1.23%—29.74%,郑单958的下降幅度为4.17%—21.82%,差异显著。

图2

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图2不同处理对不同玉米品种根干重的影响

Fig. 2Effect of different treatments on root dry weight of different maize varieties

2.1.2 对根总长度的影响不同处理玉米单株根长度表现为WS<W<S<CK（图3）,其中胁迫处理期间2个品种的W、S和WS处理比CK平均降幅为3.10%—22.56%、0.52%—11.13%和3.30%—27.32%,表现为根长度在复合胁迫下降幅最大,淹水胁迫次之,弱光胁迫影响最小;随着胁迫天数延长各处理根总长度增加,但胁迫处理与对照相比,表现为随胁迫时间延长降幅增大趋势,且在胁迫第7天时,2个品种降幅达到最大,W、S和WS处理根长度比CK平均降低22.56%、11.13%和27.23%,差异显著。不同品种比较,根长度对胁迫类型和时间响应趋势与干重基本一致,均以复合胁迫影响最大,其次是淹水和弱光,但不同品种响应程度大小不同,表现为豫玉22单株根长度降幅略大于郑单958,胁迫期间豫玉22的W、S、WS处理根长度比CK平均降低15.08%、2.14%和18.17%,而郑单958的W、S和WS处理根长度则比CK平均降低13.72%、8.46%和16.93%。

图3

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图3不同处理对不同玉米品种根长度的影响

Fig. 3Effects of different treatments on root length of different maize varieties

2.1.3 对根总表面积的影响花期淹水、弱光显著限制了玉米根表面积增加（图4）,随着处理时间延长根表面积呈增加趋势,处理间变化顺序为CK>S>W>WS,胁迫期间2个品种W、S和WS处理分别比CK降低4.18%—14.16%、1.66%—8.03%和3.25%—17.85%,复合胁迫>淹水胁迫>弱光胁迫。随着胁迫天数增加,根表面积绝对值增加,但胁迫处理与对照间的差值增大,降幅增加,如2个品种的W、S和WS处理在胁迫第3天时,W、S和WS根总表面积比CK平均减少3.93%、0.72%和8.86%,在胁迫第9天时,根总表面积比CK平均减少13.51%、8.03%和17.52%,降幅达到最大。品种间比较,胁迫处理后豫玉22根表面积降幅大于郑单958,但二者变化趋势不同,其中郑单958在胁迫5 d时,W、S和WS处理分别比CK降低15.33%、3.71%和16.03%,之后下降趋于平缓,而豫玉22则在胁迫5 d时,各处理比CK分别降低12.78%、4.42%和14.04%,之后降幅仍持续增加,到第9 天降幅达到最大,W、S和WS分别比CK降低15.25%、6.25%和19.22%。

图4

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图4不同处理对不同玉米品种根表面积的影响

Fig. 4Effect of different treatments on root superficial area of different maize varieties

2.1.4 对根总体积的影响从图5可以看出,不同处理玉米根总体积随着生育进程推进呈增加趋势,各处理单株根体积变化顺序为WS<W<S<CK,胁迫期间WS、W、S处理根总体积平均分别比CK降低1.75%—20.55%、0.21%—18.35%和1.25%—9.13%,且随着胁迫天数的增加,玉米根总体积降幅逐渐增大,在处理的第5天降幅达到最大,2个品种的WS、W和S处理根体积比CK分别降低20.55%、18.35%和9.13%,之后降幅趋于减少,且随胁迫时间延长,WS、W、S处理与CK间的根体积差值逐渐增大。2个品种对淹水、弱光及复合胁迫响应不同,其中豫玉22 W、WS和S处理的根总体积平均比CK降低14.01%、17.70%和8.40%,郑单958平均降幅分别为11.23%、14.77%和5.65%;2个品种均随胁迫天数延长降幅增加,降幅谷值出现时间不同,郑单958在第5天降幅达到最大,WS、W和S处理比CK降低19.72%、7.80%和22.08%,随后降幅减少,豫玉22在第7天降幅达到最大,其WS、W和S处理比CK分别降低17.43%、13.60%和24.32%,之后降幅仍持续降低。

图5

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图5不同处理对不同玉米品种根体积的影响

Fig. 5Effects of different treatments on root volume of different maize varieties

2.1.5 对根层数量的影响由表1可以看出,淹水和复合胁迫下玉米节根层数量呈增加趋势,W和WS处理3—5 d后,玉米节根层数比CK增加1层,胁迫9 d后,W和WS的节根层数比CK平均增加2层,差异显著,而S处理与CK无明显差异。不同品种节根层数变化对胁迫响应不同,郑单958在W和WS胁迫3 d后节根层数量比CK增加1层,胁迫7 d后比对照增加2层,达到8层,而豫玉22在W和WS胁迫5 d后节根层数量为7层,比CK增加1层,S处理与CK无明显差异。郑单958节根层数的增加量大于豫玉22,这亦是郑单958对淹水胁迫的忍耐性优于豫玉22的原因之一,是逆境胁迫下的根系的自身调节和反馈性生长。

Table 1
表1
表1不同处理对玉米节根层数量的影响
Table 1Effects of different treatments on the number of maize crown root layers

品种 Variety	处理 Treatment	节根层数Root layers
品种 Variety	处理 Treatment	1 d	3 d	5 d	7 d	9 d
郑单958 Zhengdan958	CK	6.33±0.27a	6.00±0.47a	6.33±0.27a	6.67±0.27b	6.67±0.47b
	W	6.33±0.27a	7.00±0.47 a	7.33±0.27a	8.67±0.27a	8.33±0.27a
	S	6.00±0.00a	6.33±0.27a	6.33±0.47a	6.67±0.27b	7.33±0.27b
	WS	6.67±0.47a	7.67±0.47a	7.33±0.27a	7.33±0.27b	8.00±0.00a
豫玉22 Yuyu22	CK	6.00±0.47a	6.33±0.27a	6.00±0.54a	6.33±0.00b	6.67±0.27b
	W	6.00±0.00a	6.67±0.27a	7.00±0.47a	7.67±0.54a	7.00±0.47a
	S	6.33±0.27a	6.67±0.54a	6.33±0.27a	6.33±0.27b	6.67±0.27b
	WS	6.67±0.27a	6.67±0.27a	7.00±0.27a	7.67±0.27a	7.67±0.27a

同一行不同字母表示在 0.05 水平上差异显著
Different letters mean significantly different at 0.05 probability within the same lines

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2.2 淹水弱光复合胁迫对玉米根显微结构的影响

2.2.1 对通气组织形成的影响从根系横切结构可以看出（图6）,淹水、淹水弱光复合胁迫均刺激根系通气组织形成,弱光下未形成通气组织（图6-C、G、K、O）;随着胁迫天数的延长,通气组织形态随之发生改变,在W和WS处理后3 d,2个品种的根系均形成多个性状不规则的溶生气腔（图6-B、D、J、L）,但气腔面积较小,随着处理时间延长,如在处理9 d时（图6-F、H、N、P）,气腔融合并变大,呈规则排列或无序崩解状,但根的中柱结构均较为完整。不同品种根气腔形态对胁迫的响应不同,郑单958气腔变化表现为随着胁迫天数延长,相邻的多个气腔融合为一个较大但边缘清晰（图6-F、H）、气腔间的薄壁细胞排列比较规则的大气腔,根结构保持较为完整,而豫玉22则随着淹水时间延长表现为多个小气腔融合为一个大气腔,但气腔排列不规整（图6-N、P）,气腔之间的薄壁细胞呈现断裂状,使得相邻气腔间贯通,不利于根系在缺氧环境条件下气体的存留和维持根细胞的生理功能。

图6

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图6不同处理对玉米根显微结构的影响（100×）

A—D、I—L为处理3 d;E—H、M—P为处理9 d。A：CK-郑单958;B：W-郑单958;C：S-郑单958;D：WS-郑单958;I：CK-豫玉22;J：W-豫玉22;K：S-豫玉22;L：WS-豫玉22;E：CK-郑单958;F：W-郑单958;G：S-郑单958;H：WS-郑单958;M：CK-豫玉22;N：W-豫玉22;O：S-豫玉22;P：WS-豫玉22
Fig. 6Effects of different treatments on root microstructure of maize (100×)

A-D, I-L mean stress duration is three days; E-H, M-P mean stress duration is nine days. A: CK-ZD958; B: W-ZD958; C: S-ZD958; D: WS-ZD958; I: CK-YY22; J: W-YY22; K: S-YY22; L: WS-YY22; E: CK-ZD958; F: W-ZD958; G: S-ZD958; H: WS-ZD958; M: CK-YY22; N: W-YY22; O: S-YY22; P: WS-YY22

2.2.2 对通气组织数量、面积和根孔积率的影响淹水、淹水弱光复合胁迫下,根通气组织的气腔数量和气腔面积显著增加（图7）,处理间表现为WS和W处理的根气腔数量比CK平均增幅为2.00—12.50倍和2.50—14.50倍,气腔面积则比CK分别增加1.28—19.26倍（WS）和0.87—8.17倍（W）,且淹水、复合胁迫与对照差异显著,弱光与对照无差异。随着胁迫天数延长,W和WS处理根气腔数量和气腔面积均显著增加,且在处理后的3、7和9 d二者与CK两两之间差异均达显著水平。2个品种的根气腔数量和气腔面积对不同胁迫类型的响应程度不同,其中郑单958在WS和W胁迫7 d时气腔数量达到最大,WS和W处理每平方毫米分别为183.52个和77.62个,之后下降并趋于稳定,豫玉22气腔数量在第7天每平方毫米为51.55个和70.56个,之后仍呈线性持续增加趋势;2个品种气腔面积变化趋势一致,均随胁迫时间延长,呈持续增加趋势,在W和WS处理下,豫玉22气腔面积增幅分别为0.35—9.81倍和0.49—21.45倍,郑单958增幅为1.68—6.78倍和2.49—17.39倍,表现为豫玉22增幅大于郑单958,这可能是胁迫处理后期豫玉22气腔裂解加速了气腔面积增加的原因,也是豫玉22为适应长时间胁迫通过裂解增大气腔面积从而适应胁迫的自我调节机制。

图7

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图7不同处理对不同品种根气腔数量和面积的影响

Fig. 7Effects of different treatments on root aerenchyma numbers and areas of different maize varieties

根孔积率是表征根系通气性的重要指标之一。从图8可以看出,W和WS胁迫下,根孔积率随着处理天数增加而增大,S处理与CK无差异。胁迫处理期间, WS和W处理与CK相比,根孔积率平均增加幅度分别为1.07%—28.13%和2.43%—20.42%,且随着胁迫时间延长根孔积率快速增加,胁迫处第9天时,WS和W根孔积率平均为28.13%和20.04%,与对照差异极显著。2个品种根孔积率对不同处理胁迫时间响应不同,WS和W胁迫下郑单958根孔积率快速增加,增幅为1.16%—36.5%和4.11%—22.19%,豫玉22的根孔积率增加缓慢,增幅分别为0.98%—19.75%和0.75%—17.90%,表现为豫玉22根孔积率增加速度远小于郑单958,这也是豫玉22耐涝性比郑单958差的原因之一。

图8

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图8不同处理对不同玉米品种根孔积率的影响

Fig. 8Effects of different treatments on root porosity of different maize varieties

2.3 淹水弱光胁迫对根系生理特性的影响

2.3.1 对玉米根系活力的影响淹水、弱光胁迫显著降低了玉米根系活力（图9）,处理间根活力大小次序为WS<W<S<CK,其中胁迫期间WS处理根活力平均比CK降低14.65%—75.34%,其次是W和S处理,分别比CK降低12.00%—63.67%和5.69%—15.14%,各处理与对照在处理3 d后差异达显著水平,WS处理比W和S处理在胁迫期间平均低21.28%和44.69%,差异显著。随着胁迫天数的增加,各胁迫处理根活力持续下降,且降幅增大,如处理9 d时,W、S和WS处理根系活力分别比CK下降63.57%、16.31%和75.39%,远远大于处理3 d时的降幅,差异达极显著水平。2个品种比较,以豫玉22降幅略大于郑单958,其中郑单958在W、S和WS处理下比CK降低幅度分别为8.03%—58.66%、3.98%—16.99%和9.20%—77.71%,豫玉22的降幅分别达15.76%—68.48%、7.32%—17.63%和19.81%—73.07%。

图9

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图9不同处理对不同玉米品种根活力的影响

Fig. 9Effects of different treatments on root activities of different maize varieties

2.3.2 对玉米根系总吸收面积和活跃吸收面积的影响由图10可以看出,不同处理根总吸收面积和活跃吸收面积变化趋势与根活力一致,均随着胁迫处理时间延长而下降。淹水和弱光胁迫显著降低根总吸收面积和活跃吸收面积,其中对根活跃吸收面积的影响程度大于总吸收面积。处理间以WS处理胁迫降幅最大,比CK降低2.62%—44.09%（根总吸收面积）和10.46%—59.31%（根活跃吸收面积）,其次是W处理,降幅为1.02%—31.09%（根总吸收面积）和7.12%—42.27%（根活跃吸收面积）,S处理影响较小,降幅分别为0.62%—15.96%（根总吸收面积）和4.12%—20.07%（根活跃吸收面积）。随着胁迫时间延长,根总吸收面积和活跃吸收面积降幅逐渐增大,WS处理第5天二者降幅分别为26.31%和36.24%,在第9天时则降幅达44.09%和59.31%,差异达显著水平。2个品种对胁迫时间的响应程度不同,郑单958在胁迫处理7 d时总吸收面积降幅达到最大,随后下降,豫玉22则在处理9 d时降幅达到最大;2个品种以豫玉22的降幅略大于郑单958,WS处理下豫玉22根吸收总面积和活跃吸收面积比CK分别降低2.62%—44.09%和6.65%—62.54%,而郑单958根吸收总面积和活跃吸收面积则分别降低0.57%—43.37%和13.54%—56.94%。

图10

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图10不同处理对玉米根总吸收和活跃吸收面积的影响

Fig. 10Effects of different treatments on total root absorbing and active absorbing areas of different maize varieties

2.3.3 对玉米根系活跃吸收比例的影响由图11可以看出,根系活跃吸收比随着胁迫处理整体呈下降趋势;淹水、弱光胁迫显著降低了玉米根活跃吸收比,处理间根活跃吸收比变化为WS<W<S<CK,其中WS和W处理比CK平均降幅分别8.74%—34.02%和7.93%—21.52%,S处理比CK降低幅度为4.35%—11.14%,且WS、W处理与CK间差异显著。随着胁迫处理时间延长,根系活跃吸收比呈下降趋势降。不同品种对淹水、弱光逆境胁迫响应不同,表现为豫玉22的根系活跃吸收比降幅大于郑单958,豫玉22根活跃吸收比CK分别降低2.65%—38.97%（WS）、6.70%—29.30%（W）和7.12%—12.01%（S）,且复合胁迫与单一胁迫及对照间在处理5 d后差异显著,郑单958根活跃吸收比降幅分别为14.14%—29.50%（WS）、9.02%—14.45%（W）和1.89%—11.44%（S）,复合胁迫、淹水与对照间差异显著。

图11

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图11不同处理对玉米根活跃吸收比的影响

Fig. 11Effects of different treatments on ratio of root active absorption between different maize varieties

2.4 淹水弱光胁迫对玉米产量的影响

淹水、弱光胁迫由于影响了根系形态结构和生理活性,因此使得玉米产量大幅度下降（图12）,在处理5 d后各处理间差异均达显著水平,且随着处理时间延长,产量降幅增大。处理间2个品种以WS降幅最大,平均比CK降低3.70%—40.64%,其次是W处理,比CK降低2.47%—34.44%、S胁迫下降幅较小,比CK降低2.34%—26.65%,在胁迫的第5天时,WS处理的产量比W和S处理平均降低10.63%和17.27,差异显著。品种间比较,豫玉22产量降幅大于郑单958,郑单958 WS处理的产量比CK降低3.57%—37.74%,豫玉22的WS处理产量比CK降低3.83%—43.42%,W和S则比CK分别降低1.43%—32.37%（郑单958）、3.47%—36.41%（豫玉22）和2.54%—25.94%（郑单958）、2.15%—27.34%（豫玉22）,且随着胁迫时间越长,豫玉22的降幅显著大于郑单958。

图12

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图12淹水弱光胁迫对玉米产量的影响

不同字母分别代表同一天不同处理在0.05水平上显著
Fig. 12Effects of waterlogging and low light stress on yield of different maize varieties

Different letters represent significantly different at 0.05 level of different treatments on the same day, respectively

3 讨论

3.1 淹水弱光胁迫对玉米根形态特征的影响

植物在遭受外界生物或非生物因素胁迫后,通过调整自身形态特征或改变自身形态结构来缓解灾害是植物适应外界变化的一种机制^[31]。当玉米受到洪涝灾害后,土壤水分达到饱和,含氧量急剧减少,导致根系与大气间的气体交换受阻,因此根系的自我调节就从有氧呼吸转变为无氧呼吸^[32],呼吸过程改变了能量代谢,使根系生长发育受抑,从而引起根变细、短等一系列形态特征的变化^[33]。而弱光或遮阴直接降低了叶片光合速率,进而间接影响根系生长发育,导致根干重、根长密度等根系形态特征显著降低^[34]。本试验结果发现淹水、弱光胁迫亦显著降低了玉米根干重、总根长度、根表面积和体积,且随着胁迫时间延长,降低幅度越大,这与前人的研究结果一致^[10,11,12];同时试验结果也证明淹水弱光复合胁迫后的根长、根重和根表面积和体积降低的幅度依次大于淹水胁迫和弱光胁迫,说明复合胁迫对根系造成的伤害要远大于单一胁迫,其根系除了淹水造成的直接影响,也有弱光造成的间接影响,但复合胁迫对根系造成的影响并不是二者胁迫之和,而是小于2个单一胁迫的叠加之和,2种胁迫对根形态指标的影响存在一定程度的正交互效应,说明当在植株地上部和地下部同时遭受2种胁迫时,植株可以通过自身调节,形成逆境下新的生长动态和平衡;同时本试验也证明淹水胁迫对根系造成的直接伤害要大于弱光胁迫下对根系形成的间接伤害。本试验结果亦表明玉米根系对淹水胁迫和复合胁迫具有生长性反馈和补偿机制,表现在淹水和复合胁迫玉米节根层数增加1—2层,说明根系通过增加节根层数可以补偿在淹水和淹水弱光复合胁迫下根干重、根长度、根体积等的减少或降低,进而减轻胁迫对根系生长的伤害,但弱光胁迫下由于根系受到的影响是间接的,因此并未出现节根层数增加的补偿性生长,这也是逆境直接刺激性下作物根系的自适应和自我调节的一种机制。

本试验结果表明,敏感型品种豫玉22在逆境胁迫下根生长和发育受到的影响程度远大于钝感型品种郑单958,而且钝感型品种郑单958能在胁迫后的一定时间（比如5 d）根系适应性调节生长,随后受影响程度减弱,而敏感型品种豫玉22则在7 d后才出现适应性,但仍有根干重等指标在逆境胁迫下持续下降,呈现不可逆的生长受阻。由此可见不同品种对逆境下的自我调节和适应能力大小不同,是造就不同品种耐性差异的重要原因之一。且郑单958逆境下不仅根长度、根干重和根体积高于豫玉22,而且节根层数也多于豫玉22,说明耐性强的品种不仅具备较强的自适应能力调节根系生长（增加根重和长度）,而且有较强的增强补偿生长（增加节根层数）,达到适应和抵御逆境胁迫,从而达到减轻胁迫伤害。

3.2 淹水弱光胁迫对玉米根显微结构特征的影响

前人研究发现淹水胁迫下根系融生气腔数量或通气组织的发达程度与植株耐涝性密切相关^[9],本试验结果表明,弱光胁迫下根系并未形成融生气腔或通气组织,但淹水和淹水弱光复合胁迫下融生气腔数量、面积和根孔积率的大幅度增加,使玉米根内部形成了较发达的通气组织,从而增加根区细胞的氧气供应,这是根系适应该逆境胁迫的组织结构变化特征。同时研究也表明,淹水和复合胁迫下根系通过结构的改变,如根中柱结构的完整性抑制了氧气向根外扩散,缓解淹水及复合胁迫下缺氧带来的损伤,这与前人淹水胁迫的研究结果一致^[35]。本研究结果也证明不同品种不仅对相同逆境胁迫的敏感性和响应程度不同,而且对不同逆境胁迫的响应程度及忍耐时间也存在较大差异,如对于淹水弱光适应性强的品种（郑单958）通过产生发达的通气组织维持较大气腔面积,较多的气腔数量和高的根孔积率,增强了根系内部氧气扩散,同时也保证了完整的气腔和气腔间相对规则、有序和完整排列的薄壁细胞,保证了逆境下根系相对旺盛生命活力,这也是适应性强的品种在根系结构改变上适应淹水弱光的重要根结构特征之一;而对于适应性较差品种豫玉22,虽然根内部亦形成发达的通气组织,但通气组织数量、面积和根孔积率均显著低于郑单958,且随着胁迫时间持续,气腔排列不整齐,甚至出现部分气腔间的薄壁细胞崩解,使气腔间贯穿,呈现不规则排列,该结构性特征不利于气体在根内存留和上下气体交换,加剧了根内细胞缺氧和生理功能的下降,因此根生命活力显著下降,这是2个品种对淹水及复合胁迫适应性和响应程度不同的重要机制之一,耐抗性强的品种通过保持和改变其根结构形态,从而实现其逆境胁迫下的独特耐性优势,在根系生长上亦表现出较强的适应性。

3.3 淹水弱光胁迫对玉米根生理吸收功能和产量的影响

根系活力、根系吸收面积和根活跃吸收比是客观反映根系生命活动的重要生理指标^[36,37],根系活力高,呼吸作用强,越有利于根系吸收水分和养分,同理根吸收面积和活跃吸收比越大,则根系的吸收能力越强,供给地上部生长的养分和水分就越多^[38]。本研究结果显示淹水、弱光及复合胁迫均导致根吸收活力、根吸收面积、活跃吸收面积和活跃吸收比下降,且随着胁迫时间的延长降低幅度增大,这与单一淹水胁迫下根系活力变化特征结果一致^[11,12];本研究结果表明复合胁迫对根活性和根吸收的影响程度大于单一胁迫,但并不是单一胁迫的累加,而是小于二者累加,表现出2个逆境交互下的正效应,这可能与植物受2个或多个限制因素影响后,在多种因子交互影响下新的生长或生理特性平衡所致。本研究也表明在玉米花期根吸收面积和根活力对逆境类型反应不同,淹水胁迫影响大于弱光胁迫,这主要是淹水胁迫下直接影响玉米根系呼吸,使根系以无氧呼吸为主,能量代谢减弱,导致根活力和活动下降,进而限制根养分的吸收,导致根系生长受限,吸收面积和吸收能力下降;而弱光胁迫主要通过降低玉米叶片光合作用,减少光合产物向根系供应,从而引起根活力和根吸收面积大幅度下降^[19],因此其对根系的间接影响远小于淹水胁迫的直接影响。2个品种中敏感性品种豫玉22根活力、吸收面积和活跃吸收比降低幅度要大于郑单958,这也是耐性品种郑单958比豫玉22更能适应淹水弱光胁迫的主要生理机制之一。由于淹水、弱光胁迫下根系的生长和生理功能受抑,因此地上部产量也受到严重影响,本研究结果表明,在淹水和弱光双重胁迫玉米产量降幅最大,其次是淹水胁迫。弱光胁迫对玉米产量的影响在三者之中最小。随着胁迫时间越长,产量降幅越大,同时产量变化趋势表现出与根形态结构、生理指标变化趋势的一致性。两品种以敏感性品种豫玉22产量降幅大于适应性强的品种郑单958。

4 结论

淹水、弱光和复合胁迫显著降低了玉米单株根干重、根长度、根表面积和根体积,以淹水弱光复合胁迫降幅最大,其次是淹水胁迫,弱光胁迫影响最小;随着胁迫天数的延长,2个品种均表现降幅增大,胁迫处理5—7 d是淹水、弱光胁迫的阈值。淹水、淹水复合胁迫后根系通过自身调节和补偿性生长,如改变根内部结构,增加根气腔数量、面积,增大根孔积率,增加上层节根数量减轻淹水和复合胁迫危害。淹水、弱光及复合胁迫显著降低根系活力、总吸收面积、活跃吸收面积和吸收面积比及产量,其中以复合胁迫影响最大,其次是淹水胁迫。不同品种对淹水、弱光胁迫的响应程度不同,敏感型品种受淹水弱光胁迫影响更大,程度更重,且胁迫处理后根形态指标持续下降且降幅增加,钝感型品种在胁迫天数达到阈值后根系形态指标呈适应性恢复生长趋势。

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为揭示长期淹水环境下基于形态、生物量和养分的河竹鞭根系统的生长策略,为河竹在水湿地和江河湖库消落带植被恢复中的应用提供参考,调查测定了人工喷灌供水和淹水处理3、6、12个月的河竹一年生竹鞭及其根系的形态和生理生化指标,分析了河竹鞭和鞭根形态特征和生物量分配及鞭根系统的养分吸收与平衡.结果表明: 长期淹水对河竹鞭节长、鞭径和土中根根径并无明显影响.淹水3个月整体上对鞭的形态特征影响小,水中翘鞭较少,但一定程度上抑制了根的生长.随着淹水时间的延长,水中鞭、根大量生长,同时促进了土中鞭、根的生长,但土中、水中鞭生物量和土中根生物量占总生物量的比例变化并不明显,而水中根生物量/总生物量和水中根生物量/土中根生物量显著升高,体现出河竹可以通过鞭根系统的生长调节和生物量合理分配来逐步适应淹水环境.长期淹水整体上降低了河竹土中根的根系活力,抑制了土中根对养分的吸收,但对土中根养分化学计量比的影响较小,而使水中根的根系活力显著增强,养分化学计量比产生明显的适应性调节,N/P升高,N/K和P/K降低.水中根不仅起到氧气吸收功能,还具有较强的养分吸收功能.这是河竹有效适应淹水环境的生长策略之一.

LIU Y

, CHEN S

, LI Y

, GUO Z

, YANG Q

. Adaptive adjustment of rhizome and root system on morphology, biomass and nutrient in Phyllostachys rivalis under long-term waterlogged condition
Chinese Journal of Applied Echology, 2015,26(12):3641-3648. (in Chinese)

URL [本文引用: 2]

VISSER E J

, VOESENEK L A

C J

, VARTAPETIAN B

, JACKSON M

. Flooding and plant growth
Annals of Botany, 2003,91:107-109.

DOI:10.1093/aob/mcg014 URL [本文引用: 3]

[12]

僧珊珊, 王群, 李潮海, 刘天学, 赵龙飞. 淹水胁迫下不同玉米品种根结构及呼吸代谢差异
中国农业科学, 2012,45(20):4141-4148.

DOI:10.3864/j.issn.0578-1752.2012.20.003 URL [本文引用: 3]

【Objective】The objective of this study was to identify the difference in root structure and respiration metabolism between two maize cultivars under waterlogging stress in seedling growth.【Method】A pot experiment with two maize cultivars DH662 (a susceptible maize genotype) and XD20 (a tolerant one) was conducted at scientific and educational campus of Henan Agricultural university. CK and 2, 4, 6, 8 days of waterlogging were designed for the two cultivars. The differences in root structure and respiration metabolism between two cultivars were studied. 【Result】The results showed that the root dry weight, root length, root activity of two cultivars decreased with the increase of waterlogging days. And the decreases in DH662 were more significantly than in XD20. The root dry weight in DH662 and XD20 decreased by 29.7% and 12.1%, while root activity decreased by 30.6% and 8.7% as compared with CK treatment after 8 days of waterlogging. The number of aerenchyma, the aerenchyma area and the porosity of two cultivars increased with the increase of waterlogging days. The average aerenchyma area and root porosity of two cultivars increased by 3.9 times and 2.8 times than CK treatment after 6 days of waterlogging. The average activity of alcohol dehydrogenase, pyruvate decarboxylase and lactate dehydrogenase in two cultivars increased by 27.7%, 55.0% and 2.6 times than CK treatment. And the increases in DH662 were more significantly than in XD20. 【Conclusion】Different cultivars had different responses mechanism in their tolerance to waterlogging in seedling growth. A tolerant maize cultivar had intact root structure, higher root activity and developed aerenchyma. And the anaerobic respiration was moderate. So the tolerant maize cultivar could resist waterlogging stress and increase root dry weight.

SENG S

, WANG

, LI C

, LIU T

, ZHAO L

. Difference in root structure and respiration metabolism between two maize cultivars under waterlogging stress
Scientia Agricultura Sinica, 2012,45(20):4141-4148. (in Chinese)

DOI:10.3864/j.issn.0578-1752.2012.20.003 URL [本文引用: 3]

宋学芳, 王利凯, 周竹青. 淹水诱导小麦根通气组织形成和皮层细胞超微结构变化的研究
华中农业大学学报, 2009,28(5):519-524.

[本文引用: 1]

SONG X

, WANG L

, ZHOU Z

. Aerenchyma formation and the ultrastructural changes of cortical cells in wheat roots under waterlogging
Journal of Huazhong Agricultural University, 2009,28(5):519-524. (in Chinese)

[本文引用: 1]

[14]

SAMIRA A

, WIDED

, RENAUD

, BERENICE

, PIERRE

. Assessment of enzyme induction and aerenchyma formation as mechanisms for flooding tolerance in Trifolium subterraneum‘Park’
Annals of Botany, , 2003 91:195-204.

[本文引用: 1]

[15]

JULIA B

, RUTH

. Sensing and signalling in response to oxygen deprivation in plants and other organisms
Annals of Botany, 2005,96:507-518.

DOI:10.1093/aob/mci206 URLPMID:16051633 [本文引用: 1]

AIMS AND SCOPE: All aerobic organisms require molecular di-oxygen (O2) for efficient production of ATP though oxidative phosphorylation. Cellular depletion of oxygen results in rapid molecular and physiological acclimation. The purpose of this review is to consider the processes of low oxygen sensing and response in diverse organisms, with special consideration of plant cells. CONCLUSIONS: The sensing of oxygen deprivation in bacteria, fungi, metazoa and plants involves multiple sensors and signal transduction pathways. Cellular responses result in a reprogramming of gene expression and metabolic processes that enhance transient survival and can enable long-term tolerance to sub-optimal oxygen levels. The mechanism of sensing can involve molecules that directly bind or react with oxygen (direct sensing), or recognition of altered cellular homeostasis (indirect sensing). The growing knowledge of the activation of genes in response to oxygen deprivation has provided additional information on the response and acclimation processes. Conservation of calcium fluxes and reactive oxygen species as second messengers in signal transduction pathways in metazoa and plants may reflect the elemental importance of rapid sensing of cellular restriction in oxygen by aerobic organisms.

[16]

周新国, 韩会玲, 李彩霞, 郭树龙, 郭冬冬, 陈金平. 拔节期淹水玉米的生理性状和产量形成
农业工程学报, 2014,30(9):119-125.

URL [本文引用: 1]

为了探明夏玉米拔节期对淹水历时的响应规律，采用大田环境下无底测坑试验，在玉米拔节期设置不同的淹水天数（1、2、3、5、7 d），分析了淹水历时对夏玉米生长发育、灌浆过程、物质分配及产量性状的影响。结果表明，玉米拔节期淹水抑制玉米的营养期发育，淹水1、2、3、5、7d的平均株高分别比非涝渍环境下玉米（CK）降低2.26%、2.26%、2.45%、11.36%和10.17%；平均叶面积指数LAI分别降低23.79%、18.93%、13.04%、32.74%和34.27%；玉米拔节期淹水5 d以上，植株矮而黄。在植株生理反应方面，淹水3 d后测定结果表明，淹水1、2、3 d的叶绿素质量分数比CK高，根系活力增强，而淹水5d和7d叶绿素质量分数和根系活力下降。玉米灌浆至乳熟期叶绿素测定结果表明，淹水5 d以上处理的叶绿素质量分数仍较CK降低10.87%，表明受淹5 d以上，叶绿素质量分数降低并无法恢复。玉米拔节期受淹影响其后期灌浆过程中的籽粒质量，同一时间的淹水1、2和3 d与对照籽粒质量比较接近，淹水5 d较低，淹水7 d为最低。玉米穗长和穗粗随淹水历时呈减小的趋势，但各处理间无显著差异（P<0.05）。淹水使玉米出现较长的秃尖，淹水1、2、3、5 d的秃尖长度为CK的2倍左右，淹水7 d的秃尖长度为CK的5倍；淹水历时越长，玉米穗长、穗粒质量、穗质量和百粒质量的减幅就越大，淹水1、2、3、5、7的玉米产量分别降低16.58%、16.65%、26.11%、34.32%和39.01%。玉米拔节期淹水5 d以上，严重影响玉米正常生长，造成产量显著降低。研究结果为涝渍灾害监测和灾损快速评估以及涝渍排水标准确定提供参考。

ZHOU X

, HAN H

, LI C

, GUO S

, GUO D

, CHEN J

. Physiological characters and yield formation of corn (Zea mays L.) under waterlogging stress in jointing stage
Transactions of the Chinese Society of Agricultural Engineering, 2014,30(9):119-125. (in Chinese)

URL [本文引用: 1]

REN B

, ZHANG J

, LI

, FAN

, DONG S

, LIU

, ZHAO

. Effects of waterlogging on the yield and growth of summer maize under field conditions
Canadian Journal of Plant Science, 2013,94:23-31.

DOI:10.4141/cjps2013-175 URL [本文引用: 1]

[18]

REN B

, ZHANG J

, DONG

, LIU

, ZHAO

. Effects of duration of waterlogging at different growth stages on grain growth of summer maize ( Zea mays L.) under field conditions
Journal of Agronomy and Crop Science, 2016,202:564-575.

DOI:10.1111/jac.2016.202.issue-6 URL [本文引用: 1]

[19]

燕树锋, 齐建双, 铁双贵, 岳润青, 韩小花, 卢彩霞. 遮阴对黄淮海玉米主栽品种农艺性状和产量的影响
中国农学通报, 2016,32(33):49-54.

[本文引用: 2]

YAN S

, QI J

, TIE S

, YUE R

, HAN X

, LU C

. Effects of shading on agronomic characters and yield of major maize cultivars in Huang-Huai-Hai Region
Chinese Agricultural Science Bulletin, 2016,32(33):49-54. (in Chinese)

[本文引用: 2]

[20]

CUI H

, JAMES

, CAMBERATO

, JIN L

, ZHANG J

. Effects of shading on spike differentiation and grain yield formation of summer maize in the field
International Journal of Biometeorology, 2015,59:1189-1200.

DOI:10.1007/s00484-014-0930-5 URLPMID:25380975 [本文引用: 1]

A field experiment was conducted to study the effects of shading on tassel and ear development and yield formation of three summer maize hybrids Zhenjie 2 (ZJ2), Denghai 605 (DH605), and Zhengdan 958 (ZD958). The ambient sunlight treatment was used as control (CK) and shading treatments (40 % of ambient sunlight) were applied at different growth stages from silking stage (R1) to physiological maturity stage (R6) (treatment S1), from the sixth extended leaf stage (V6) to R1 (treatment S2) and from seeding to R6 (treatment S3). Shading had no significant effect on the time from seeding to shoot emergence (VE); however, subsequent growth and development were delayed with shading beyond this point. The differentiation time of both tassel and ear delayed, and female spike (tassel) floret differentiation, sexual organ formation time, and anthesis-silking interval (ASI) were lengthened. After shading, the total number of floret, silk, and fertilization floret reduced significantly; the number of abortive seeds increased, and the total setting percentage among different treatments showed that CK>S2>S1>S3; and the total setting percentages in S1, S2, and S3 of ZD958 were 44, 72, and 15 % respectively. The total floret number of tassel primordium differentiation, fertility rate, and seed setting rate of florets in S3 treatment was the minimum; kernels per ear decreased seriously and single ear setting percentage was only 16 %; although floret degeneration number of S2 during ear differentiation stages increased and floret fertility rate reduced than that of CK, fertilization flower seed production increased and abortive seed decreased after canceling shading. Aborted kernel of S1 increased and kernel dry weight reduced, resulting in a significant decrease of kernel number per ear and kernel weight, and the grain abortive rate of 40-62 %. In conclusion, shading changed the growth and development process and caused infertility of tassel and ear; tassel branches decreased, reducing pollen vitality and silks differentiation cut down; and grain dry matter accumulation and setting percentage decreased, causing yield reduction. Grain yield and biomass reduced 66, 36, and 93 % compared to the control by shading treatments of S1, S2, and S3, respectively.

[21]

胡海文, 李晓红. 低温弱光对番茄叶片和根系中抗氧化酶系统的影响
井冈山示范学院学报(自然科学), 2003,24(5):19-22.

[本文引用: 1]

HU H

, LI X

. Effects of chilling under low light on antioxidant enzymes in leaves and roots of tomato
Journal of Jinggangshan Normal College (Natural Sciences), 2003,24(5):19-22. (in Chinese)

[本文引用: 1]

[22]

高佳, 史建国, 董树亭, 刘鹏, 赵斌, 张吉旺. 花粒期光照强度对夏玉米根系生长和产量的影响
中国农业科学, 2017,50(11):2104-2113.

[本文引用: 1]

GAO

, SHI J

, DONG S

, LIU

, ZHAO

, ZHANG J

. Effect of different light intensities on root characteristics and grain yield of summer maize (Zea Mays L.)
Scientia Agricultura Sinica, 2017,50(11):2104-2113. (in Chinese)

[本文引用: 1]

[23]

石德扬, 李艳红, 夏德军, 张吉旺, 刘鹏, 赵斌, 董树亭. 种植密度对夏玉米根系特征及氮肥吸收的影响
中国农业科学, 2017,50(11):2006-2017.

DOI:10.3864/j.issn.0578-1752.2017.11.006 URL [本文引用: 1]

【Objective】Maize is the first food crop in China, which plays an important role in national food security. Using density-tolerance hybrids and increasing plant density is one of the primary measures to achieve high yields of maize in modern times. However, the high planting density increased the pressure of maize growth space, resulting in the growth of single plant inhibited and the yield per plant decreased, at the same time, as the major organ to absorb moisture and nutrients from soil, the roots' growth can be inhibited by high plant density. To ascertain the relationship between the root characteristics of density-tolerance hybrids and grain yield, and nitrogen utilization under high plant density is the base of studying the genotype differences of root characteristics of different summer maize hybrids to plant density, and which is significant for root improvement of density-intolerance hybrids and management of nutrients and moisture under high planting density.【Method】This experiment was conducted during 2014-2015 at the Huanghuaihai Regional Corn Research Center of Shandong Agricultural University. With Zhengdan 958 (ZD958, density-tolerance hybrid) and Ludan 981 (LD981, density-intolerance hybrid) as the experimental materials, using the soil column culture in combination with the ¹⁵N-labeling technique, the responses of root characteristics, as well as nitrogen uptake and utilization, of different density-tolerance varieties to increased density were investigated at two planting densities (D1, 52 500 plants/hm² and D2, 82 500 plants/hm²). 【Result】Grain yield of maize significantly increased with the increase of plant density, while the grain yield per plant of both hybrids significantly reduced. Over the growing process of both hybrids, the root biomass, length, surface area and active absorbing area of both hybrids were decreased with the increase of plant density. In D1 treatment, all root indicators of LD981 were higher than those of ZD958 at early growth stage but then turned to be lower or significantly lower than ZD958 after milk stage. In D2 treatment, no significant differences in various root indicators were observed between the two hybrids at early growth stage; however, the root indicators of LD981 were significantly lower than those of ZD958 at late growth stage. The leaf area per plant and net photosynthetic rate of ear leaf changed in a trend consistent with that of roots. The difference in root-shoot ratio in biomass under the impact of density increase was not significant between the two hybrids; but their root-shoot ratio in active area was significantly reduced. The N accumulation amount (NAA) per plant and N use efficiency (NUE) of both hybrids were significantly reduced, but the N fertilizer recovery rate (NRR) and the nitrogen partial factor productivity (NPFP) significantly improved with plant density increased. In addition, the proportion of N from fertilizer in NAA was not affected by the changes of density. In D2 treatment, the N content per plant, ratio of fertilizer N, NRR and NPFP of ZD958 were significantly higher than LD981. 【Conclusion】The roots of ZD958 proved to be less affected by plant density. At high density, it could maintain relatively high root weight, length, absorbing area and activity, and longer high value duration, which were beneficial to N uptake, the photosynthetic production and obtaining higher grain yield. This suggests that the well-developed roots can guarantee the plant nitrogen uptake at high density, contributing to the photosynthetic production of the aboveground part and thus achieving higher grain yield. The bigger seed set and stronger seed set adjustment ability of ZD958 promoting nitrogen were the primary reason of its higher NUE and NPFP than LD981 at high plant density.

SHI D

, LI Y

, XIA D

, ZHANG J

, LIU

, ZHAO

, DONG S

. Effects of planting density on root characteristics and nitrogen uptake in summer maize
Scientia Agricultura Sinica, 2017,50(11):2006-2017. (in Chinese)

DOI:10.3864/j.issn.0578-1752.2017.11.006 URL [本文引用: 1]

于晓波, 罗玲, 曾宪堂, 苏本营, 龚万灼, 雍太文, 杨文钰, 张明荣, 吴海英. 套作弱光胁迫对大豆苗期根系形态和生理活性的影响
中国油料作物学报, 2015,37(2):185-193.

DOI:10.7505/j.issn.1007-9084.2015.02.010 URL [本文引用: 1]

 Root morphology characteristics, physiological activity and biomass accumulation were studied to investigate the root response to shading under relay-intercropping system in seedling stage. 3 varieties with different root characteristics, NTS1007, GX-3 and ND12 were used in the pod experiment to investigate root activity, root surface area （RSA）, root active absorption area （RAAA）, bleeding sap and biomass accumulation. Compared with the monoculture, the results showed that the length of main root and lateral root decreased significantly in the relay strip intercropping system, and the increase in lateral root （81.8%） was more obvious than that of main root （42.8%）. The soluble sugar content, root activity, bleeding sap, root surface area, and root active absorption area all decreased significantly. The decreasing amplitude of root surface and active absorption area were linearly correlated with the first lateral root length. Biomass decreased and the decrease in the root biomass （55.2%） was more apparent than shoot （37.9%）. Among the 3 varieties, ND12 had the least decrease in main root length, first lateral root length and root volume （33.9%, 74.4%, 65.3%）, but GX-3 had the most significant decrease in RSA and biomass （67.1%, 48.3%） in the relay strip intercropping system, and NTS had the greatest decreasing aptitude in R/S, root activity and bleeding sap/shoot dry matter （35.4%,39.2%,38.9%）. In a relay strip intercropping system, the elongation growth of the soybean root can reflect the status of the root growth more accurately in comparison to monoculture, which can be used as an important indicator of shade-tolerance. ND12 had a rational allocation of assimilation to alleviate the negative effect on morphogenesis and physiological characteristics.

YU X

, LUO

, ZENG X

, SU B

, GONG W

, YONG T

, YANG W

, ZHANG M

, WU H

. Response of roots morphology and physiology to shading in maize-soybean relay strip intercropping system
Chinese Journal of Oil Crop Sciences, 2015,37(2):185-193. (in Chinese)

DOI:10.7505/j.issn.1007-9084.2015.02.010 URL [本文引用: 1]

王丽, 邓飞, 郑军, 赵柳, 任万军, 杨文钰. 水稻根系生长对弱光胁迫的响应
浙江大学学报(农业与生命科学版), 2012,38(6):700-708.

URL [本文引用: 1]

Rice (Oryza sativa L.) as a photophilous crop, often encounters low-light environment during the growth stage in rice-producing areas particularly in Sichuan. Low-light stress seriously affects the morphology, physiology, grain yield and quality of rice. However, the response of rice root system to low-light stress is not so far clear. Therefore, we seeks to examine the responses of five rice varieties to low-light stress at different growth stages through pot experiments under artificially-controlled shading condition using white cotton yarn screen. By a completely randomized design, the pot experiments were carried out on the experimental farm of Sichuan Agricultural University in 2009. In experiment 1, one-layer and two-layer white cotton yarn screens, which shaded about 53 % and 73 % of the full light intensity respectively, were covered on the top of rice canopy of Gangyou 906 at tillering-elongation stage, elongation-booting stage, booting-heading stage, and heading-maturing stage respectively. In experiment 2, the response of root system of Ⅱ you 498, Gangyou 188, Gangyou 527 and Chuanxiang 9838 to shading was studied at tillering-elongation stage and booting-heading stage by covering with one-layer white cotton yarn screen. The screens were more than 2.0 m above the ground to ensure good ventilation and were large enough to fully cover the shaded plots. Plants without covers were set as control (CK). Root/shoot ratio, root volume, maximal root length, root total absorbing area, root active absorbing area and root α-naphthylamine oxidizing activity were analyzed at the end of shading treatment. The results were as follows: 1) Root volume, root total absorbing area and root active absorbing area of Gangyou 906 were decreased with the increase of shading degree before filling stage, resulting in root growth retard (Fig. 1, 2). At tillering-elongation stage and elongation-booting stage, shading greatly (P < 0.05) reduced root volume, and the decline was severe with the increase of low-light stress. As compared with the control, root volume was significantly decreased (P < 0.05), but the decrement with treatment of 53 % shading was greater than that of 73 % shading at booting-heading stage. Root total absorbing area and active absorbing area significantly (P < 0.05) decreased with the increase of shading intensity at elongation-booting stage and booting-heading stage. After heading stage, the root system growth was promoted, while the root senescence was delayed under 53 % shading treatment. Meanwhile, the root volume, root total absorbing area and active absorbing area increased by 14.6 %, 17.5 % and 39.5 % respectively with 53 % shading treatment. However, 73 % shading treatment had negative effects on root volume, root total absorbing area, root active absorbing area and α-naphthylamine oxidizing activity in roots (Fig. 1-3). 2) The responses of different varieties to shading treatment were different. Shading significantly (P < 0.05) reduced root α-naphthylamine oxidizing activity, root absorbing area and active absorbing area of Ⅱyou 498, Gangyou 188 and Gangyou 527 (Table 3, 4), leading to the hindrance of the formation and capacity of moisture and mineral nutrients of root system. But for Gangyou 906, the root α-naphthylamine oxidizing activity with 53% and 73% shading treatment at tillering-elongation stage and booting-heading stage were 104.7 %, 35.5 %, 83.2 %, and 0.5 % respectively higher than those of non-shading treatment. It can be concluded that different degrees of shading have different influences on root system characteristics of rice at each growth stage, and strong shade-tolerant variety such as Gangyou 906, can reduce the disadvantaged effect on grain yield of rice by improving the vigor of root system. It also suggests that the root α-naphthylamine oxidizing activity and root active absorbing area can be used as effective indicators to identify the low-light tolerance of rice with the grey correlation degree analysis (Table 5). All these results lay a theoretical foundation for the selection of shade-tolerant variety and the improvement of cultivation technology.

WANG

, DENG

, ZHENG

, ZHAO

, REN W

, YANG W

. Response of root system growth to low-light stress in indica rice
Journal of Zhejiang University(Agriculture and Life Sciences), 2012,38(6):700-708. (in Chinese)

URL [本文引用: 1]

周卫霞, 李潮海, 刘天学, 王秀萍, 闫志广. 弱光胁迫对不同耐荫型玉米果穗发育及内源激素含量的影响
生态学报, 2013,33(14):4315-4323.

DOI:10.5846/stxb201204250591 URL [本文引用: 2]

2010-2011年以耐荫性较弱的玉米杂交种豫玉22和耐荫性较强的玉米杂交种郑单958为材料,在抽雄前3 d开始进行弱光胁迫处理,吐丝后10 d恢复自然光照,研究弱光胁迫及光恢复对不同耐荫型玉米果穗生长发育及其内源激素含量的影响。结果表明:弱光胁迫下,玉米果穗生长发育明显减缓,穗长、穗粗和果穗干物质积累显著减小,秃尖度变大;穗行数、穗粒数和籽粒库容显著降低;吐丝期果穗顶部小穗子房发育停滞,已有败育迹象的籽粒在恢复自然光照后无明显改善;豫玉22果穗和籽粒性状在处理间的差异程度均大于郑单958。弱光胁迫下,两玉米杂交种果穗的ABA和ZR含量均升高,而GA含量和GA/ABA比值均降低;IAA含量和IAA/ABA比值在郑单958果穗中表现为升高,而豫玉22则表现为下降。

ZHOU W

, LI C

, LIU T

, WANG X

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