外源脱落酸缓解小麦幼苗铜胁迫伤害的生理机制初探

为了解脱落酸(ABA)缓解小麦幼苗铜胁迫伤害的生理机制,采用营养液培养方法,研究了外源ABA对0.5mmol·L~(-1) Cu~(2+)胁迫下小麦幼苗叶绿素、可溶性糖含量及抗氧特性的影响。结果表明,0.5mmol·L~(-1) Cu~(2+)胁迫对小麦幼苗伤害明显,降低了叶片叶绿素和可溶性糖含量及根、叶片超氧化物歧化酶(SOD)活性,提高了根和叶片丙二醛含量。铜胁迫下,添加1μmol·L~(-1) ABA可显著提高小麦幼苗叶片叶绿素和可溶性糖含量及根和叶片过氧化物酶(POD)、叶片SOD活性,降低叶片铜含量。说明适宜浓度的外源ABA可通过调节渗透调节物质含量、增强抗氧化酶活性来减轻铜胁迫对小麦幼苗的伤害,提高其抗铜胁迫能力。     

磷对盐胁迫下玉米幼苗脂质过氧化特性及抗氧化酶活性的影响

采用水培试验,研究不同浓度磷对盐胁迫下玉米幼苗生长、叶片和根系中脂质过氧化特性及其抗氧化酶活性的变化。研究表明,盐胁迫下,增施磷可明显缓解盐胁迫对玉米幼苗生长的抑制,各器官含水量增加,改善植株体内的水分代谢状况。随磷含量增加,玉米幼苗叶片细胞膜透性逐渐降低,叶绿素含量增加,叶片和根系中SOD、CAT和POD活性明显增加,以1 mmol/L磷处理酶活性最高;0.25 mmol/L磷处理叶片和根系中MDA的含量显著增加,且根系的增幅大于叶片。磷可通过提高盐胁迫下玉米幼苗植株体内抗氧化酶活性、降低膜脂过氧化水平,缓解盐胁迫对玉米幼苗伤害,从而增强对盐胁迫的适应性。     

脱落酸对干旱胁迫下茶树生理特性的影响

脱落酸（Abscisic acid,ABA）是一种重要的植物激素,在植物对胁迫耐受性和抗性中发挥着重要作用。以茶树品种迎霜为材料,分别采用100 mg·mL^-1、200 mg·mL^-1聚乙二醇6000（PEG 6000）模拟干旱胁迫,研究了外源ABA对干旱胁迫下茶树叶片生理生化特性的影响。结果表明：喷施外源ABA后,渗透调节物质含量和抗氧化酶活性略有提高。干旱胁迫下,外源ABA能提高茶树体内脯氨酸、可溶性糖及可溶性蛋白含量,同时增强了抗氧化酶活性,从而降低干旱胁迫对茶苗的伤害。经ABA处理后的茶苗在复水后,渗透调节物质含量和抗氧化酶活性均保持较高值,外源ABA对提高茶树抗旱性起到一定的作用。     

干旱对两种金花茶幼苗抗氧化能力及渗透物质含量的影响

以龙州和显脉两种金花茶幼苗为材料,通过缺水方式进行干旱胁迫处理,以探讨金花茶幼苗抗氧化能力以及渗透含量变化对干旱胁迫的响应.结果表明:(1)随着干旱胁迫时间的延长,金花茶幼苗叶片的相对含水量、叶绿素含量逐渐减少,但相对电导率、H202、MDA、可溶性总糖、脯氨酸的含量却逐渐升高；叶片的抗氧化酶SOD、CAT活性呈先升后降的趋势.(2)干旱胁迫下,与显脉金花茶相比,龙州金花茶的叶绿素含量和抗氧化酶活性较高,其叶片的相对电导率、H202和MDA积累量低于显脉金花茶.说明叶片的高活性的抗氧化能力和渗透物质含量的增加促进龙州金花茶叶片的保水能力,减轻干旱胁迫伤害.     

外源5-氨基乙酰丙酸对干旱胁迫下降香黄檀幼苗生长、根系生理特性的影响

以1.5年生降香黄檀幼苗为试材,通过溶液培养的方式,研究不同浓度(0、10、25、50、100 mg/L)的5-氨基乙酰丙酸(5-ALA)对聚乙二醇(PEG-6000)模拟干旱胁迫条件下降香黄檀幼苗的生长发育、根系性状、光合色素含量、抗氧化酶活性、丙二醛含量、有机渗透调节物质含量等生理生化指标的影响。结果表明:PEG-6000胁迫14 d后,降香黄檀幼苗的苗高、地径、根、茎、叶干重、叶片相对含水量、叶绿素a含量、叶绿素b含量、类胡萝卜素含量显著下降,MDA含量显著上升,而抗氧化酶(SOD、POD)活性和有机渗透调节物质含量(可溶性糖、可溶性蛋白质)、根系活力明显下降。同时,一定浓度的外源5-ALA降低了PEG-6000引起的降香黄檀幼苗生理上的干旱胁迫,其中以25 mg/L处理时效果最好,且与PEG处理相比,叶片相对含水量、叶绿素a含量、叶绿素b含量、类胡萝卜素含量、SOD与POD活性、可溶性糖与可溶性蛋白含量、根系活力分别提高了157.95%、34.44%、33.33%、24.49%、84.66%,87.66%、59.23%、76.8%、62.72%,MDA含量则降低了37.81%。因此,根系施用外源5-ALA可促进干旱胁迫下降香黄檀幼苗的生长,并可通过提高根系的抗氧化酶活性和渗透调节物质含量来增加其抗旱性,其适宜浓度为25 mg/L。     

外源抗坏血酸对镉毒害小麦幼苗的缓解作用

为了解抗坏血酸(AsA)对Cd2+毒害小麦幼苗生长的缓解作用,以小麦品种周麦27为材料,采用室内水培法分析了在Cd2+胁迫下小麦幼苗经不同浓度AsA处理后的生长及生理变化。结果表明,外源AsA能显著提高Cd2+胁迫下小麦幼苗的株高、根长、地上部干重、根系干重、根系活力、光合色素含量、渗透调节物质含量、抗氧化酶活性及叶片净光合速率、气孔导度和蒸腾速率,显著降低丙二醛含量和相对电导率以及叶片胞间CO2浓度。说明Cd2+胁迫下外源AsA可以通过提高小麦幼苗渗透调节物质含量及抗氧化酶活性来清除活性氧自由基,减少其对光合色素蛋白大分子的攻击作用,降低膜脂过氧化伤害程度,维持光合作用和细胞膜的稳定性,从而缓解了Cd2+对幼苗生长的毒害作用,其中以35mg·L-1 AsA的缓解效果最好。     

外源硅对NaCl胁迫下玉米幼苗渗透调节物质含量影响

采用水培法研究外源硅对盐胁迫下玉米幼苗可溶性糖、游离氨基酸等渗透调节物质含量的影响。结果表明,盐胁迫下适量的增加硅供应能增加叶片和根系中渗透调节物质含量,其中根系中游离氨基酸、可溶性蛋白和可溶性糖含量的增加幅度大于叶片;同时能增加玉米幼苗各器官K+的含量,降低不同部位Na+含量,维持玉米幼苗体内的离子平衡。研究表明,硅参与盐胁迫下渗透调节物质在植物中的运输和分配,适宜浓度的硅能提高玉米耐盐性。     

干旱胁迫下冠菌素(COR)对花生幼苗叶片抗氧化酶活性及细胞膜透性的影响

在玻璃日光温室条件下,以花生品种鲁花11号为供试材料,系统研究了PEG-6000模拟干旱胁迫条件下COR对花生幼苗叶片抗氧化酶活性及细胞膜透性的影响。结果表明,正常水分条件下,0.01μmol·L~(-1) COR浸种对花生幼苗叶片相对含水量(RWC)、游离氨基酸含量、保护酶活性和细胞膜相对透性无明显影响;PEG-6000模拟干旱胁迫条件下,COR浸种可显著提高SOD、POD、CAT活性,增加游离氨基酸含量,降低细胞膜相对透性,提高幼苗叶片RWC,从而降低干旱胁迫对花生幼苗造成的伤害。     

外源ABA和BR在提高油菜幼苗耐渍性中的作用

以甘蓝型油菜中双9号为植物材料,应用外源ABA和BR处理渍水胁迫的油菜幼苗,研究其在缓解油菜幼苗渍水伤害中的作用。结果显示,短期(0～12d)渍水处理可促进油菜生长,长期(18d)渍水处理则抑制油菜生长,尤其是BR;外源ABA(75.67µmol/L)和BR(0.21µmol/L)可有效缓解长期渍水胁迫对油菜幼苗的伤害作用,干物质积累量较单纯渍水处理增加19.52%和26.22%;外源ABA和BR处理还可延缓叶绿素含量的降低,提高叶片光合能力;提高抗氧化酶(SOD、POD和CAT)活性,降低膜脂过氧化(MDA含量降低);增加叶片可溶性糖含量。说明外源ABA和BR处理通过促进渍水胁迫下油菜幼苗光合作用,提高抗氧化酶活性,提高渗透调节物质含量来增强植株抗渍能力。     

脱落酸对PEG胁迫下小麦幼苗渗透调节物质和抗氧化性的影响

为了明确脱落酸对PEG(聚乙二醇)胁迫下小麦幼苗渗透调节物质和抗氧化性的影响,筛选其有效增强小麦幼苗抗旱性的最适施用浓度,选用小麦品种洛旱6号为试验材料,采用室内水培法研究了在20%PEG胁迫下小麦幼苗经不同浓度脱落酸(ABA)处理后的形态及生理指标。结果表明:PEG胁迫下,外源ABA能够提高小麦幼苗可溶性糖、可溶性蛋白质和氨基酸含量,增强超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,降低超氧阴离子自由基■、过氧化氢(H_2O_2)含量,减少丙二醛(MDA)积累,促进小麦幼苗地上部生长。试验表明,外施ABA可通过提高小麦幼苗渗透调节能力和抗氧化酶活性来降低活性氧产生速率,减轻膜脂过氧化程度,维持细胞膜的稳定性,缓解PEG胁迫对小麦幼苗生长的抑制作用。本试验条件下以8 mg/L ABA效果最好。     

干旱胁迫下外源海藻糖对糯玉米幼苗生理特性的影响

以苏玉糯5号为供试材料,研究干旱胁迫条件下外源海藻糖对糯玉米幼苗根系和叶片抗氧化系统及渗透调节物质的影响。结果表明,干旱胁迫显著降低叶片叶绿素含量和根系活力,喷施外源海藻糖后这两类物质含量增加。干旱胁迫下喷施外源海藻糖增加玉米根系和叶片中可溶性蛋白、可溶性糖、抗坏血酸(AsA)、还原型谷胱甘肽(GSH)含量,增强糯玉米幼苗根系和叶片的超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)等活性,降低超氧阴离子产生速率(O2-)、丙二醛(MDA)等含量。外源海藻糖处理下叶片中可溶性糖、可溶性蛋白、AsA和GSH含量增加幅度大于根系,叶片中丙二醛含量降幅大于根系。表明喷施外源海藻糖缓解干旱胁迫对叶片伤害效果大于根系。干旱胁迫下喷施外源海藻糖能够增强糯玉米抗旱能力,减小干旱伤害。     

稀土元素钕对玉米幼苗根系抗旱性的影响

采用10%聚乙二醇6000模拟干旱胁迫,研究稀土元素钕对干旱胁迫下玉米幼苗根系抗旱性的影响。结果表明,干旱胁迫显著提高根系丙二醛(MDA)含量和过氧化氢(H_2O_2)含量,提高超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性,显著降低了过氧化物酶(POD)、谷胱苷肽转移酶(GST)、谷胱甘肽过氧化物酶(GPX)活性,显著降低抗坏血酸(As A)和谷胱苷肽(GSH)含量及根系生物量。干旱胁迫加剧了根系的氧化胁迫,玉米幼苗根系通过增强抗氧化酶活性抵抗干旱胁迫。外源氯化钕(NdCl_3)处理可显著提高干旱胁迫下玉米幼苗根系抗氧化酶SOD、POD、CAT、GST、GPX活性,显著提高AsA和GSH含量和根系生物量,显著降低MDA和H_2O_2含量,对APX活性无显著影响。盆栽实验结果进一步说明,NdCl_3对轻度和中度土壤干旱下玉米幼苗抗旱性均具有促进作用,对中度土壤干旱下玉米幼苗的抗旱性促进作用更佳。NdCl_3可提高玉米幼苗根系的抗旱能力,缓解干旱胁迫造成的伤害。     

水杨酸和甜菜碱浸种对低温干旱胁迫下玉米苗期生长的影响

沙培条件下,研究不同浓度水杨酸和甜菜碱浸种后对胁迫下玉米萌发和解除胁迫后苗期生长性状的影响,比较不同胁迫类型间的药剂浸种效果差异。结果表明,与低温胁迫相比,低温干旱双胁迫使玉米发芽势、地上部干鲜重和鲜重根冠比极显著下降。水杨酸和甜菜碱均能显著提高不同胁迫下玉米子粒发芽势,显著减少可溶性糖含量。对于幼苗高度和幼苗干鲜重,药剂浸种表现为低温胁迫下抑制效果和低温干旱双胁迫下促进作用。根系总长对药剂浸种的响应强于其他根系性状,且对甜菜碱的响应更为显著;地上部生长对水杨酸的响应强于甜菜碱。随着药剂浓度升高,水杨酸效果减弱,甜菜碱效果增强。     

干旱胁迫咖啡嫁接苗内源激素及生物量的变化

为探明咖啡嫁接苗应对干旱胁迫其内源激素变化对植株生长的影响,布置了盆栽试验.接穗为中粒种咖啡'大丰1号',砧木分别为大粒种咖啡'查理种16号'(种间嫁接)和中粒种咖啡'热研2号'(种内嫁接),3种水分处理:(1)正常淋水土壤含水量(soil moisture content,SMC),18％≤SMC≤25％,(2)轻度...     

Tuber age as a contributory factor in the water relations of potato (solanum tuberosum L.)

Seed tuber age effects on the response of potato plants (cv Alpha) to different drought stress regimes during the pre-tuberization period were evaluated. During a slow drying cycle of approximately 2 weeks’ duration, young expanding leaves on plants grown from young or old seed tubers showed no evidence of osmotic adjustment and pre-stressing the plants did not affect this situation. Pre-stressed plants from young and old tubers possessed a higher relative water content at a zero turgor potential than unstressed plants. However, tuber age did not affect significantly the relative water content at zero turgor potential. Plants derived from young seed tubers exhibited improved drought resistance such as reduced water loss from mature leaves, a larger root/shoot dry weight ratio and possible effects on root distribution in soil.     

外源亚精胺对PEG胁迫下燕麦幼苗生长及部分生理特性的影响

为探讨外源亚精胺(Spd)对燕麦幼苗生长和抗旱性的影响,选用燕麦品种坝莜1号为材料,以PEG-6000模拟水分胁迫,采用砂培法研究了叶面喷施不同浓度(0.3、0.6、0.9和1.2mmol·L~(-1))外源Spd后燕麦幼苗生长、活性氧代谢、抗氧化酶活性及非酶抗氧化剂和渗透调节物质含量的变化。结果表明,PEG胁迫显著抑制了燕麦幼苗生长。在PEG胁迫下,与只喷施蒸馏水的对照相比,0.6mmol·L~(-1) Spd处理对燕麦幼苗根系活力、抗坏血酸(ASA)含量和抗坏血酸过氧化酶(APX)活性具有显著的促进作用;喷施0.9mmol·L~(-1)外源Spd明显提高了燕麦幼苗的株高、根长、生物量积累,抑制了O_2~-·、H_2O_2和膜脂过氧化产物MDA的生成,增强了超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和谷胱甘肽还原酶(GR)的活性,降低了游离氨基酸含量,促进了脯氨酸、可溶性糖和可溶性蛋白的积累,维持了较高的渗透调节能力;1.2mmol·L~(-1)外源Spd处理后幼苗生长、抗氧化能力和渗透调节作用出现下降趋势。综合来看,在PEG胁迫下,叶面喷施0.9mmol·L~(-1)Spd可通过提高幼苗抗氧化和渗透能力,维持生物膜系统的稳定,减轻渗透胁迫对幼苗的伤害,促进生长和增强抗旱性。     

Root signalling and osmotic adjustment during intermittent soil drying sustain grain yield of field grown wheat

A field study was conducted to investigate the effect of intermittent soil drying on resulting non-hydraulic and hydraulic root signals, leaf gas exchange, leaf growth, day of heading, leaf osmotic adjustment and yield of wheat grown in sand and loam soils in lysimeters. A 40-day-drought treatment was imposed when the flag leaf started to emerge and was terminated close to maturity. Soil water content and soil water potential of various soil layers were measured using the neutron moderation method and tensiometers, respectively. Soil drying in the top soil layers induced increase in both xylem and bulk-leaf abscisic acid (ABA) content and reduced the stomatal conductance and leaf growth even before a measurable change in leaf water potential could be detected in droughted plants when compared with fully watered plants. Further, heading and flowering occurred 4 days earlier in the droughted than in the well-watered plants before any loss in leaf water potential had occurred as compared with the fully watered plants. When more severe drought reduced the leaf water status, further accumulation of leaf ABA occurred and transpiration decreased in addition to gradual osmotic adjustment and senescence of older leaves. The osmotic adjustment sustained leaf turgor pressure during soil drying. At severe drought, the osmotic adjustment at full turgor in the flag leaves was 0.85 MPa. In sand, the kernel dry weight increased and as a result similar grain yield was obtained in both the treatments. In loam which had more water available than sand, no significant reduction in the final yield was induced by the drought. It is concluded that (1) non-hydraulic root signals caused early drought adaptation at mild water stress by reducing leaf growth and stomatal conductance and hastening of heading and flowering; (2) osmotic adjustment sustained turgor maintenance and hence the yield-forming processes during moderate and severe water stress.     

基于主成分分析的玉米萌发期抗旱性综合评定

试验在人工气候室内利用称重法精确控制75%和35%土壤相对含水量(RWC),通过分析播种后7 d不同玉米品种的发芽率、根系生长、干物质转化等对干旱胁迫的响应差异,对10个玉米品种进行萌发期抗旱性综合评定。结果表明,干旱胁迫降低了玉米的发芽势、发芽率、发芽指数、种子萌发抗旱指数、地上部与地下根物质积累和贮藏物质转运率,增大了根冠比。利用主成分分析与热图分析得出,玉米萌发期抗旱鉴定的四级指标分别为干物质积累量、发芽指数和种子萌发抗旱指数;根长、根冠比和根干重等;根体积和贮藏物质转运率;发芽势。将指标按照对抗旱性影响的差异分为4类,发芽率、发芽指数、种子萌发抗旱指数;根体积、贮藏物质转运率;根冠比;根长和芽长。依据综合值对10个玉米品种萌发期抗旱性评价,其抗旱性强弱依次为浚单29、蠡玉35、五谷704、吉祥1号、先玉335、博优989、郑单958、伟科702、农玉2号、登海605。     

Genotypic Variation in Response of Rainfed Lowland Rice to Prolonged Drought and Rewatering

Abstract

Duration of the drought period is important for plant response during drought and after rewatering. We hypothesized that, if drought duration is extended, (1) high seedling vigor and rapid development of a deep root system will not be advantageous, and (2) osmotic adjustment will be more important. Six diverse rice (Oryza sativa L.) genotypes were selected from rainfed lowland germplasms to examine the development of a deep root system and osmotic adjustment, and their relationship with biomass production during drought and after rewatering, under two different drought durations (shorter and prolonged) in the greenhouse. NSG19 and KDML105 had greater seedling vigor (larger seedling biomass), developed a deep root system earlier in response to drought, extracted soil water more quickly, and their pre-dawn leaf water potential declined more rapidly during the prolonged drought period. These two genotypes showed superior drought recovery even after a prolonged drought period in which they suffered a greater reduction in transpiration, water use efficiency, and biomass production. The superior recovery ability was associated with larger plant size by the end of the drought period rather than with plant water status during drought, such as osmotic adjustment or leaf water potential. Osmotic adjustment was greater during prolonged drought periods (ca. 0.7 MPa) than during shorter drought periods (ca. 0.5 MPa), and lower osmotic adjustment was mostly associated with a higher leaf water potential. Genotypic variation in osmotic adjustment was observed, but there was no clear relationship between osmotic adjustment and biomass production during drought periods. These patterns of response of rice seedlings to drought and rewatering in the greenhouse should help to explain the patterns of adaptation of rainfed lowland rice in the field. Selection for drought recovery ability should be an advantageous strategy for early season drought.