干旱低磷胁迫对不同品种小麦根系导水率的影响

控制磷素水平,采用控制灌水量(正常供水、中度及重度干旱胁迫)的盆栽试验法,选择抗旱性小麦品种陕合6号(W1)和水分敏感型品种郑引1号(W2)为供试材料。用压力室法测定了三叶期的两品种小麦根系导水率(LPr)的变化规律。结果表明：陕合6号,在有磷正常供水处理( PH)下具有较高的导水率,干旱胁迫时LPr降低较少,且复水后有较强的恢复能力。郑引1号, PH的LPr值相对较小,干旱导致的根系导水率下降非常突出,复水后的恢复能力也较弱。另外,干旱胁迫对小麦苗期根系导水率的影响大于磷胁迫对其导水率的影响,且两品种小麦无磷止常供水处理(-PH)的LPr分别为 PH的31．9%和53．6％,即磷对前者LPr的影响大于后者。     

氮磷亏缺对玉米根系水流导度的影响

在人工气候室水培条件下,从单根和整株根系两个层次研究了N、P营养与玉米(Zea mays L.)根系水流导度(root hydraulic conductivity,Lpr)间的关系。结果表明：表型抗旱的杂交种F1代户单4号和母本天四的单根水导和整株根系水导均高于不抗旱的父本478,其中天四的单根水导最高,而户单4号的整株根系水导最高。N、P亏缺均使玉米单根水导和整株根系水导降低,但与N亏块相比,P亏缺的植株具有较高的整株根系水导和较低的单根水导。整株根系的水导更能反映植物根系的输水性能。     

渗透胁迫对小麦幼苗根系呼吸的影响

用PEG—6000调节培养液的渗透势,研究了渗透胁迫对小麦幼苗根系呼吸作用的影响。在-0.5 MPa的溶液中根总呼吸强度显著降低,不同苗龄根的反应差异明显;随胁迫加强呼吸强度随之降低;根系ATP含量减少。在胁迫初期呼吸废物对呼吸强度的降低无补偿作用,而在后期(72 h后)则可提高呼吸强度。 中度水分胁迫下,HMP支路活性上升,EMP-TCAO途径活性降低;抗氰呼吸活性增大,而对氰敏感的系统活性减低;细胞色素氧化酶活性显著低于对照。     

水分胁迫和氮素营养对小麦根苗生长及水分利用效率的效应

采用目前生产上广泛种植的小麦品种小偃６号,在一种特制木盒中土培,研究了水分胁迫和氮素营养对小麦根系和幼苗生长及水分利用效率（ＷＵＥ）的效应。小麦根系生长在双层尼龙网之间,土壤中的水分和养分可以被正常吸收,但主根和侧根不能穿过。结果表明：在土壤含水量为田间持水量的４０％－７０％范围内,随着土壤干旱程度的增加,小麦根长（ＲＬ）、根干重（ＲＤＷ）、叶面积（ＬＡ）和ＷＵＥ显著降低。氮肥的效应更为复杂。随着     

干旱胁迫对玉米幼苗根系中NO信号转导的影响

以玉米(Zea mays L.)幼苗根系为材料,研究其生长发育对内外源NO的感应及在干旱条件下内外源NO对其生长发育的影响.结果表明:干旱抑制根系NO释放,NO的产生可能不依赖于NO合酶系统,而依赖于NADPH硝酸还原酶的酶促反应;用活性氧清除剂NAC、NAC与干旱复合处理均能促使内源NO的产生和释放:其根系生物量的分析表明内源NO的释放明显抑制根系的生长发育.     

土壤水分胁迫对小麦根系与旗叶衰老的影响

随土壤水分胁迫加剧,旗叶,根中的超氧化物歧化酶,过氧化氢酶活性降低,腊脂过氧化产物丙二醛含量增加,花后１４ｄ为膜脂过氧化作用加重的转折点,此时受水分胁迫愈重,旗叶与根中ＳＯＤ,ＣＡＴ活性降低愈迅速,ＭＤＡ含量迅速升高,根系活力,旗叶与根中可溶性蛋白含量骤降,加重了膜脂过氧化程度,降低了清除了自由基能力,加速植株衰老。     

干旱胁迫对小麦幼苗根系生长和叶片光合作用的影响

采用水培试验方法,以2个耐旱性不同的小麦品种(敏感型望水白和耐旱型洛旱7号)为材料,研究了干旱胁迫对小麦幼苗根系形态、生理特性以及叶片光合作用的影响,以期揭示小麦幼苗对干旱胁迫的适应机制.结果表明： 干旱胁迫下,2个小麦品种幼苗的根系活力显著增大,而根数和根系表面积受到抑制;干旱胁迫降低了望水白的叶片相对含水量,提高了束缚水/自由水,而对洛旱7号无显著影响;干旱胁迫降低了2个小麦品种叶片的叶绿素含量、净光合速率、蒸腾速率、气孔导度和胞间CO2浓度,但随胁迫时间的延长,洛旱7号的叶绿素含量和净光合速率与对照差异不显著;干旱胁迫降低了2个小麦品种幼苗的单株叶面积,以及望水白的根系、地上部和植株生物量,而对洛旱7号无显著影响.水分胁迫下,耐旱型品种可以通过提高根系活力、保持较高的根系生长量来补偿根系吸收面积的下降,保持较高的根系吸水能力,进而维持较高的光合面积和光合速率,缓解干旱对生长的抑制.     

砷胁迫对小麦根系生长及活性氧代谢的影响

在水培和盆载条件下研究了砷对小麦根系生长及活性氧代谢的影响。结果表明：随砷浓度的提高,小麦胚根、次生根条数减少,总根长度、胚芽长度缩短、根体积、干重也较对照冯少超氧物歧化酶（ＳＯＤ）活性下降趋势,质脂过氧化产物（ＭＤＡ）含理增加,质膜相对透性增大、泪科越冬期,拔节期、灌浆期表现出同样的趋势。     

Changes in Root Hydraulic Conductivity During Wheat Evolution

A better understanding of the mechanisms of water uptake by plant roots should be vital for improving drought resistance and water use efficiency (WUE). In the present study, we have demonstrated correlations between root system hydraulic conductivity and root characteristics during evolution using six wheat evolution genotypes (solution culture) with different ploidy chromosome sets (Triticum boeoticum Bioss., T. monococcum L.: 2n=2x=14;T. dicoccides Koern., T. dicoccon (Schrank) Schuebl.:2n=4x=28;T. vulgare Vill., T. aestivum L. cv. Xiaoyan No. 6:2n=6x=42). The experimental results showed that significant correlations were found between root system hydraulic conductivity and root characteristics of the materials with the increase in ploidy chromosomes (2x→6x) during wheat evolution. Hydraulic conductivity of the wheat root system at the whole-plant level was increased with chromosome ploidy during evolution, which was positively correlated with hydraulic conductivity of single roots, whole plant biomass,root average diameter, and root growth (length, area), whereas the root/shoot ratio had an inverse correlation with the hydraulic conductivity of root system with increasing chromosome ploidy during wheat evolution. Therefore, it is concluded that that the water uptake ability of wheat roots was strengthened from wild to modern cultivated species during evolution, which will provide scientific evidence for genetic breeding to improve the WUE of wheat by genetic engineering.     

Changes in Root Hydraulic Conductivity During Wheat Evolution

A better understanding of the mechanisms of water uptake by plant roots should be vital for improving drought resistance and water use efficiency (WUE). In the present study, we have demonstrated correlations between root system hydraulic conductivity and root characteristics during evolution using six wheat evolution genotypes (solution culture) with different ploidy chromosome sets (Triticum boeoticum Bioss., T. monococcum L.: 2n = 2x = 14; T. dicoccides Koern., T. dicoccon (Schrank) Schuebl.: 2n = 4x = 28;T. vulgare Vill., T. aestivum L. cv. Xiaoyan No. 6: 2n = 6x = 42). The experimental results showed that significant correlations were found between root system hydraulic conductivity and root characteristics of the materials with the increase in ploidy chromosomes (2x→6x) during wheat evolution. Hydraulic conductivity of the wheat root system at the whole-plant level was increased with chromosome ploidy during evolution, which was positively correlated with hydraulic conductivity of single roots, whole plant biomass,root average diameter, and root growth (length, area), whereas the root/shoot ratio had an inverse correlation with the hydraulic conductivity of root system with increasing chromosome ploidy during wheat evolution. Therefore, it is concluded that that the water uptake ability of wheat roots was strengthened from wild to modern cultivated species during evolution, which will provide scientific evidence for genetic breeding to improve the WUE of wheat by genetic engineering.     

根施甜菜碱对镍胁迫下小麦幼苗生长生理的影响

以普通小麦品种‘轮选988’为材料,采用溶液培养法,研究了根施不同浓度甜菜碱(1.0、2.0、3.0、4.0、5.0、10.0、15.0、20.0mmol·L~(-1))对镍(100μmol·L~(-1) NiSO_4)胁迫下小麦根系生长的影响,以及4.0mmol·L~(-1)甜菜碱处理镍胁迫幼苗根系相关抗逆生理生化指标的变化。结果表明:(1)与不施加镍对照相比,镍胁迫下小麦幼苗的根长、株高、鲜重和干重分别显著降低了14.7%、11.7%、15.0%和16.7%。(2)与单独镍胁迫处理相比,小麦幼苗的根长、株高、鲜重和干重均随着根施甜菜碱的浓度逐渐增加且呈先升后降的趋势,并以4.0mmol·L~(-1)外源甜菜碱处理效果较佳。(3)与单独镍胁迫处理相比较,在4.0mmol·L~(-1)外源甜菜碱处理下,小麦幼苗根系超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性分别升高了284.7%、40.3%、82.9%和20.4%,超氧阴离子自由基(O-·2)含量、过氧化氢(H_2O_2)含量和丙二醛(MDA)含量分别显著降低了50.6%、38.4%和40.6%,可溶性糖含量及游离脯氨酸(Pro)含量分别显著降低了19.2%、45.4%,而根系活力大幅上升了358.0%。研究认为,根施适宜浓度外源甜菜碱可显著增强小麦幼苗根系的抗氧化能力,恢复根系活力,从而有效减弱镍胁迫对小麦幼苗生长的伤害。     

Hydrogen Peroxide Appears to Mediate a Decrease in Hydraulic Conductivity in Wheat Roots under Salt Stress

Changes in the root diameter were measured in wheat, Triticum aestivum L., using a sensor of small displacements in osmotic experiments, and the hydraulic conductivity (L _p) of the root was calculated by the method of initial flows. The L _p decreased by two to three times during 30-min exposure in 0.1–9 mM H₂O₂. In 150 mM NaCl, changes in L _p exhibited two-phase kinetics: an initial increase in L _p by two and a half to three times, followed by a decrease to 1.6–50% of the control level within the subsequent 24 h. After one-day-long exposure of the roots in a solution containing 150 mM NaCl and 100 mg/l catalase, L _p did not differ from the control level. Root pretreatment with salicylate, which promotes the formation of H₂O₂, prevented the initial increase in L _p in 150 mM NaCl, probably, due to a drastic L _p decrease. The activity of guaiacol peroxidase in the roots increased by three times within the 20-min exposure of the roots to the salt solution. The data suggest that hydrogen peroxide can mediate the L _p decrease during the first day of salinity stress.     

硝普钠对铝胁迫下黑麦和小麦根尖线粒体功能的影响

硝普钠（SNP）能够缓解铝对黑麦和小麦根伸长生长的抑制效应。铝降低黑麦和小麦的呼吸速率和P／O、OPR、R3、R4、RCR值以及线粒体膜H^＋-ATP酶、H^＋-PP酶、Na^＋-K^＋-ATP酶、Ca^2＋-ATP酶、Mg^2＋-ATP酶活性,而SNP则能提高铝胁迫下呼吸速率、P/O、OPR、R3、R4、RCR值和这些酶活性。说明铝胁迫导致黑麦和小麦根尖细胞线粒体呼吸功能受损,氧化磷酸化解耦联。黑麦受损程度较小麦低,具有较强耐铝能力。SNP作为一氧化氮（NO）的供体,推测NO可以有效减轻铝胁迫导致的小麦根尖线粒体呼吸功能障碍,从而能够缓解铝毒害。     

多效唑浸种对渗透胁迫下玉米根边缘细胞发生的影响

以‘农大108’玉米种子为材料,采用不同浓度(50、100、150、200、250、300、350 mg·L-1)的多效唑溶液进行浸种处理,研究其对渗透胁迫(20％ PEG-6000)下玉米种子萌发、根系生长和根系边缘细胞数目、活性及黏胶层厚度的影响.结果表明:与对照相比,渗透处理抑制了玉米种子露白与根系生长,增加了边缘细胞数目与黏胶层厚度.预先用多效唑浸种后再进行渗透胁迫处理进一步降低了主根的长度,但增加侧根的生长而使根系鲜重增加,进一步增加了根边缘细胞黏胶层厚度,在一定程度上减少了由于渗透胁迫造成的边缘细胞数目的增加程度.无论是渗透处理还是预先用多效唑浸种处理对边缘细胞活性的影响均不大.可见,多效唑浸种能够增加玉米根系的抗旱能力与边缘细胞黏胶层厚度的增加有关,而与边缘细胞数目、活性的关系不大;多效唑浸种溶液的适宜浓度范围为200～250 mg·L-1.     

外源一氧化氮对镉胁迫下玉米幼苗根生长及氧化伤害的影响

以玉米幼苗为材料,通过在镉处理的同时补充外源一氧化氮(NO)供体硝普钠(SNP)及其类似物[K3Fe(CN)6]、以及NO消除剂,分析NO对植物耐镉性的影响,探讨NO在植物逆境胁迫响应中的作用及其机理。结果显示:添加20μmol·L-1 SNP能显著降低镉引发的玉米幼苗根生长抑制及根尖内源镉的积累,减少电解质的渗漏以及超氧化物自由基(O2.-)和过氧化氢(H2O2)的上升幅度,抑制超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性的增加,进一步提高镉胁迫下谷胱甘肽还原酶(GR)的活性。SNP的上述效应可被NO消除剂2-(4-羧基-2-苯基)-4,4,5,5-四甲基咪唑-1-氧-3-氧化物(cPTIO)所逆转,而SNP类似物K3Fe(CN)6的应用对上述反应几乎无影响,说明该反应具有NO特异性。研究表明,外源NO能够显著缓解镉胁迫对玉米幼苗生长造成的伤害,该缓解作用主要是通过降低植株体内内源镉积累和减轻镉诱发的氧化伤害来实现的。     

植物根系水分导度及影响因素

根系水分导度（Lpr）是表示根系吸收和运输水分能力的生理指标,文章介绍Lpr的研究进展。     

硫营养对小麦籽粒淀粉合成及相关酶活性的影响

在田间条件下,研究了施硫对小麦籽粒淀粉合成及相关酶活性的影响.结果表明:在0～20 cm土层土壤有效硫含量为5.84 mg/kg的地块上施硫不仅提高了小麦籽粒中蔗糖的含量,而且催化蔗糖降解代谢的蔗糖合成酶(SS)活性提高,利于籽粒蔗糖的降解.施硫显著提高了灌浆期间籽粒可溶性淀粉合成酶(SSS)活性,并使腺苷二磷酸葡萄糖焦磷酸化酶(ADPGPPase)和束缚态淀粉合成酶(GBSS)活性在灌浆中、后期维持在较高水平,对直链和支链淀粉的合成都起促进作用, 使总淀粉积累增加,千粒重提高,产量增加.