重金属递进胁迫对黑麦草初期生长的影响

通过研究Cu²⁺、Zn²⁺、Cd²⁺与Pb²⁺胁迫对黑麦草初期生长的影响,结果表明：4种重金属对种子发芽率抑制效应相对较小,尤其Cu²⁺与Zn²⁺的抑制作用最小。高浓度Cu²⁺、Cd²⁺胁迫对株高、根系长度、地上生物量的抑制作用相对较大,尤其Cu²⁺对根系生长的抑制效应最大,在300 mg·L^-1下,与对照相比,根长最高下降了 85.48%。高浓度Cd²⁺胁迫显著降低了叶绿素含量,在300 mg·L^-1时比对照降低了45.51%;与对照相比,Cu²⁺与Zn²⁺所有处理都增加了叶绿素含量。从递进胁迫进程看,一些重金属对某一生长指标的影响往往表现在低浓度具有促进作用,而高浓度又存在明显的抑制效应。     

Cu胁迫对狭叶香蒲体内元素吸收分配的影响

采用水培法,研究了不同浓度Cu²⁺胁迫下狭叶香蒲（Typha angustifolia）体内Cu及其他元素吸收分配的变化。结果表明：狭叶香蒲地上部和根系累积的Cu量均随Cu²⁺浓度升高显著增加;在同一浓度Cu²⁺胁迫下,根中Cu的累积量明显高于地上部。根系同一组织中的Cu百分含量随Cu²⁺浓度的升高均显著增加;同一Cu²⁺浓度下,根系各组织中Cu含量均表现为：中柱>皮层>表皮。低浓度（1和5 mg·L^-1）Cu²⁺对地上部及根中Ca、Mg含量及地上部Mn含量均无显著影响,但高浓度（80和100 mg·L^-1）Cu²⁺可促进植株对Ca的吸收,显著降低对Mg﹑Mn和Zn的吸收。较高浓度（55～100 mg·L^-1）Cu²⁺胁迫后,根系各组织对Ca的吸收增加,对Zn的吸收降低;55～80 mg·L^-1 Cu²⁺胁迫下根系不同组织对Cl和K的吸收增加,但高浓度（100 mg·L^-1）Cu²⁺胁迫下则显著降低。根系累积的Ca、Zn和K主要分配到中柱中,Cl主要分配到皮层中.     

外源一氧化氮对铅胁迫下小麦种子萌发及幼苗生理特性的影响

利用室内水培实验,研究了外源一氧化氮（NO）供体硝普钠（SNP）对Pb²⁺处理下小麦（Triticum aestivum L.）种子萌发、幼苗生长及相关生理指标变化的影响。结果表明,Pb²⁺处理使小麦种子发芽势、发芽率、幼苗根长和茎长均显著降低,诱导叶绿素a、叶绿素b含量减少及叶绿素荧光参数F_v/F_m和F_v/F_o的比值减小,25 μmol·L^-1 SNP明显缓解Pb²⁺胁迫对种子萌发及幼苗生长的抑制作用,提高Pb²⁺胁迫下叶绿素a、叶绿素b含量及F_v/F_m和F_v/F_o的比值,而100 μmol·L^-1SNP无明显缓解作用。此外,25和100 μmol·L^-1SNP诱导Pb²⁺胁迫下小麦幼苗叶片过氧化氢酶（CAT）活性增强和可溶性蛋白含量增多,但100 μmol·L^-1SNP处理降低了过氧化物酶（POD）活性。结果说明,外源NO促进Pb²⁺胁迫下小麦种子萌发及幼苗生长,提高叶绿素和可溶性蛋白含量,诱导CAT活性升高,从而增强小麦对Pb²⁺胁迫的适应性。     

镉胁迫对丹参生长及有效成分积累的影响研究

采用盆栽试验方法,研究了镉（Cd2＋）对丹参（Salvia miltiorrhiza Bunge）的生长及其有效成分积累的影响。结果表明,镉胁迫下丹参的生长受到了显著抑制,体内Cd2＋残留量、可溶性蛋白含量和膜脂过氧化程度显著增加,叶绿素含量降低。与对照相比,镉胁迫下丹参叶片水溶性酚酸类化合物咖啡酸和迷迭香酸的含量显著降低（P〈0．05）,原儿茶酸含量增加,丹参素、原儿茶醛和丹酚酸B的含量也降低,但变化均不显著（P〉0．05）。而根系中这6种酚酸类化合物含量均降低,其中迷迭香酸的含量变化极显著（P〈0．01）。镉胁迫下丹参根系脂溶性丹参酮类化合物二氢丹参酮、丹参酮I和隐丹参酮含量均显著降低,而丹参酮lIA含量变化不显著。丹参叶片中水溶性酚酸类化合物合成关键酶苯丙氨酸解氨酶（PAL）和酪氨酸氨基转移酶（TAT）的活性显著降低,而肉桂酸4一羟化酶（C4H）和4一香豆酸CoA连接酶（4CL）的活性显著升高。这些结果均说明镉胁迫可以降低丹参的产量和质量。     

AtsHsp17.6-CⅠ和AtsHsp17.6-CⅡ基因对非生物胁迫的应答研究

小分子热激蛋白是植物受到热胁迫后的主要表达产物之一,与植物细胞耐热有密切关系。该研究发现,拟南芥小分子热激蛋白基因AtsHsp17.6-CⅠ和AtsHsp17.6-CⅡ 除热激之外,重金属离子Ni⁺、Pb²⁺、Cu²⁺、Zn²⁺和Al³⁺均能诱导这2个热激蛋白基因的表达;氧化胁迫和渗透胁迫同样也能诱导它们表达。该研究将由CaMV35S启动子驱动的这2个小分子热激蛋白基因导入拟南芥,RT-PCR分析表明,2个小分子热激蛋白基因在转基因植物中呈现组成型表达。实验结果表明,组成型表达小分子热激蛋白基因AtsHsp17.6-CⅠ的转基因植物表现出对6 μmol·L^-1 Cd²⁺胁迫、0.4% NaCl胁迫的耐受性。研究表明,这2个小分子热激蛋白基因可能参与着多种抗逆途径,推测其能够减轻或抵抗逆境胁迫引起的伤害并对其进行修复。     

不同生长季节丹参营养器官中有效成分的动态变化

分析了三年生丹参不同季节营养器官中几种有效成分的变化规律。结果表明：（1）丹参地上部分丹参素、原儿茶醛和咖啡酸的含量在整个生长季节中显著高于根的;丹酚酸B和迷迭香酸的含量除8月份达到最高和最低外,其他月份差异不显著;（2）6-8月地上部分的5种水溶性酚酸类成分的含量均显著变化,而根中除咖啡酸在6月积累较低外,其它酚酸在整个生长季节的积累量变化不明显;（3）在整个生长季节,根系丹参酮ⅡA和隐丹参酮含量变化不显著,而二氢丹参酮和丹参酮Ⅰ的含量呈现上升趋势。总体来说,三年生丹参秋季采挖为宜,其地上部分水溶性成分含量较大,值得进一步开发。     

外源脯氨酸（Pro）对茶菱抗Cd2+胁迫能力的影响

以高等水生植物茶菱（Trapella sinensis Olive）为材料,研究了外施不同浓度的脯氨酸（Pro）对Cd²⁺毒害的缓解效应。结果表明,茶菱体内Pro含量在单一Cd²⁺毒害下明显增加,外施Pro后,显著降低;叶绿素和可溶性蛋白含量在单一Cd²⁺毒害下大幅下降,外施Pro后,失绿症状有所减轻;保护酶（SOD、CAT、POD）系统在单一Cd²⁺毒害下比例失调,平衡被打破,活性下降,外施Pro后,SOD、POD活性较对照升高,CAT持平,其比例维持在正常范围内;O^－₂产生速率在单一Cd²⁺毒害下大大加快,外施Pro后,其产生速率恢复正常水平;丙二醛（MDA）含量在单一Cd²⁺毒害下积累加剧,外施Pro后,积累程度有所降低。因此,外源Pro可以通过减轻叶绿素和可溶性蛋白的降解,促进蛋白合成,减缓MDA积累,降低O^－₂产生速率,增强保护酶活性来增强植物对重金属胁迫的抗性,增强植物对逆境的适应能力。本实验中Pro作用的最佳浓度范围为40~60 mg·L^-1。     

盐胁迫下构树幼苗各器官中K+、Ca2+、Na+和Cl-含量分布及吸收特征

将当年生构树幼苗置于含有不同浓度（04、1、2、3、4 g·kg^-1）NaCl的土壤中,研究其生物量积累、叶片细胞质膜透性和K⁺、Ca²⁺、Na⁺、Cl^-等离子的吸收、分布及运输,并观察盐害症状.结果表明：构树幼苗的叶片质膜透性随着NaCl浓度的增加和胁迫时间的延长而升高,根冠比随NaCl浓度的升高而增加,大于3 g·kg^-1的土壤盐胁迫对构树叶片的质膜透性及植株的生物量积累影响显著.构树幼苗各器官中Na⁺和Cl^-含量随土壤NaCl浓度升高而显著增加,K⁺和Ca²⁺则随之降低,叶片各离子含量均明显高于根和茎.说明盐胁迫影响根系对K⁺和Ca²⁺的吸收,并抑制了它们向地上部分的选择性运输,使叶和茎的K⁺和Ca²⁺含量下降.构树通过吸收积累Na⁺和Cl^-抵御土壤盐分带来的渗透胁迫,但过量的Na⁺和Cl^-积累会造成单盐毒害.作为抗盐性较高的非盐生植物,构树地上部分的拒盐作用不显著.     

镉胁迫对矮牵牛种子萌发、幼苗生长及抗氧化酶活性的影响

采用营养液培养的方法研究了不同浓度镉Cd（0、1、2和4 mmol·L^-1）处理对矮牵牛（Petunia hybrida）种子萌发、幼苗生长及生理特性的影响。结果发现：与对照相比,较低浓度（1 mmol·L^-1）Cd处理下矮牵牛种子萌发和幼苗生长均显著被抑制,当Cd浓度增至4 mmol·L^-1时完全抑制了矮牵牛种子的萌发。Cd胁迫在低浓度时激活矮牵牛幼苗叶片过氧化物酶（POD）、过氧化氢酶（CAT）活性,而高浓度产生抑制效应;抗坏血酸过氧化物酶（APX）和超氧化物歧化酶（SOD）活性与对照相比均显著升高,丙二醛（MDA）含量无显著变化。不同浓度的乙二胺四乙酸(EDTA)的加入使4 mmol·L^-1 Cd胁迫下矮牵牛幼苗叶片POD和APX活性增加,但不影响SOD和CAT活性;此外,6 mmol·L^-1 EDTA使Cd胁迫下矮牵牛幼苗叶片中MDA含量增加。结果表明,Cd胁迫抑制矮牵牛种子萌发和幼苗生长,却使幼苗叶片POD、CAT和APX活性增加,EDTA的加入能够进一步提高Cd胁迫幼苗POD和APX活性。因此,矮牵牛幼苗在Cd胁迫下具有较强的抗氧化损伤的能力。     

外源NO对盐胁迫下黑麦草幼苗活性氧代谢、多胺含量和光合作用的影响

采用溶液培养法研究了外源一氧化氮(nitric oxide,NO)供体硝普钠(sodium nitroprusside,SNP)对100 mmol·L^-1 NaCl胁迫下黑麦草幼苗生长、活性氧代谢、多胺含量和光合作用的影响。结果表明,50 μmol·L^-1 SNP显著提高盐胁迫下黑麦草幼苗叶片的超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性及谷胱甘肽(GSH)、精胺(Spm)、亚精胺(Spd)含量和(Spm+Spd)/Put比值,降低了腐胺(Put)、超氧阴离子(O^—·₂)、H₂O₂和丙二醛(MDA)含量,使幼苗叶片叶绿素和类胡萝卜素含量、净光合速率(P_n)和气孔导度(G_s)升高,胞间CO₂浓度(C_i)下降,相对生长量增加。叶绿素荧光动力学资料显示,SNP处理降低盐胁迫下黑麦草叶片的初始荧光(F₀),表明它对光合膜系统具有保护效应。SNP处理不仅提高了盐胁迫下叶片的最大荧光(F_m)、PSⅡ潜在光化学效率(F_v/F₀)和PSⅡ最大光化学效率(F_v/F_m),而且提高了PSⅡ实际光化学效率(Φ_PSⅡ)、光化学荧光猝灭系数(q_P)、表观光合电子传递速率(ETR)和光化学速率(PCR),降低了非光化学荧光猝灭系数(NPQ)和天线热耗散(D),而1 mmol·L^-1 NO清除剂PTIO和0.5 μmol·L^-1 NaNO₂处理(对照)则无此效应。由此表明,外源NO可能通过提高植株的抗氧化能力及光能的捕获与转换而增强盐胁迫下黑麦草叶片的光合能力,从而缓解盐胁迫对幼苗生长的抑制作用。     

Penconazole induced changes in photosynthesis, ion acquisition and protein profile of Mentha pulegium L. under drought stress

Effect of penconazole (PEN) treatment on drought-stressed Mentha pulegium L. plants was investigated. Six weeks after sowing, seedlings were grown under soil moisture corresponding to 100, 75, 50 and 25 % field capacity (FC) with or without PEN (15 mg l⁻¹) for 4 weeks. Results showed that the seedlings at 75 % FC showed maximum growth and water supply lower than 75 % FC was the threshold of drought-initiated negative effects on seedling growth. Drought stress significantly induced proline and carbohydrate contents and the decreased chlorophyll, photosynthesis parameters, soluble proteins and ion accumulations. Exogenous PEN increased the growth parameters, pigments, photosynthesis and ion accumulations in drought stressed and unstressed plants, but the effects of PEN were more significant under water deficit conditions. PEN also reduced the negative effects of drought by osmotic balance and protein accumulations. Electrophoretic patterns indicated that PEN treatment increased the intensity of some protein bands with the molecular weights of 30 kDa in shoot and 31 kDa in roots, and several new protein bands with the molecular masses between 116 and 14 kDa appeared in leaves, shoots and roots. These results suggest that the PEN application can be a useful tool in alleviation of effects of drought stress in M. pulegium plants.     

Effect of water deficit on carbohydrate status and enzymes of carbohydrate metabolism in seedlings of wheat cultivars

The effect of water deficit on carbohydrate status and enzymes of carbohydrate metabolism (alpha and beta amylases, sucrose phosphate synthase, sucrose synthase, acid and alkaline invertases) in wheat (Triticum aestivum L.) was investigated in the seedlings of drought-sensitive (PBW 343) and drought-tolerant (C 306) cultivars. The water deficit was induced by adding 6% mannitol (water potential -0.815 Mpa) in the growth medium. The water deficit reduced starch content in the shoots of tolerant seedlings as compared to the sensitive ones, but increased sucrose content in the shoots and roots of tolerant seedlings, indicating their protective role during stress conditions. It also decreased the alpha-amylase activity in the endosperm of seedlings of both the cultivars, but increased alpha and beta amylase activities in the shoots of tolerant ones. Sucrose phosphate synthase (SPS) activity showed a significant increase at 6 days of seedling growth (DSG) in the shoots of stressed seedlings of tolerant cultivar. However, SPS activity in the roots of stressed seedlings of sensitive cultivar was very low at 4 DSG and appeared significantly only at day 6. Sucrose synthase (SS) activity was lower in the shoots and roots of stressed seedlings of tolerant cultivar than sensitive ones at early stage of seedling growth. Higher acid invertase activity in the shoots of seedlings of tolerant cultivar appeared to be a unique characteristic of this cultivar for stress tolerance. Alkaline invertase activity, although affected under water deficit conditions, but was too low as compared to acid invertase activity to cause any significant affect on sucrose hydrolysis. In conclusion, higher sucrose content with high SPS and low acid invertase and SS activities in the roots under water deficit conditions could be responsible for drought tolerance of C 306.     

Cadmium induced oxidative stress and changes in soluble and ionically bound cell wall peroxidase activities in roots of seedling and 3–4 leaf stage plants of <Emphasis Type="Italic">Brassica juncea</Emphasis> (L.) czern

Metabolic adaptations to heavy metal toxicity in plants are thought to be related with developmental growth stage and the type of metal by which plant is affected. In the present study, changes in ionically bound CWP, soluble peroxidase activity, H(2)O(2) level and Malonaldehyde content in roots of cadmium and copper stressed seedlings and cadmium stressed 3-4 leaf stage plants of Brassica juncea were investigated. Cadmium inhibits root growth and reduces fresh biomass. The reduction in root growth and fresh biomass is correlated with increased lipid peroxidation and reduced tolerance. Treatment with cadmium resulted in an increase in ionically bound CWP activity in roots of seedlings but no significant change in its activity was found in roots of 3-4 leaf stage plants. Increased level of H(2)O(2) in roots of cadmium and copper treated seedlings, show a direct correlation with increased activity of ionically bound CWP. H(2)O(2) level in 3-4 leaf stage plant roots was found to be very low. Soluble peroxidase activity decreased in cadmium (50 and 100 mu-icroM) treated seedlings but it was ineffective to cause any change in its activity in 3-4 leaf stage plants. Copper treated seedlings showed an increase in ionically bound CWP activity, H(2)O(2) level and MDA content. Ascorbic acid (50 mM) pretreated seedlings shows significant decrease in ionically bound CWP activity when exposed to 50 muM cadmium. Hence, it is concluded that inhibition of root growth in Brassica juncea seedlings by cadmium, is associated with CWP catalyzed H(2)O(2) dependent reactions which are involved in metabolic adaptations to heavy-metal stress.     

水杨酸和茉莉酸甲酯对丹参幼苗叶片显微结构、光合及非结构糖积累的影响

研究了水杨酸(SA)和茉莉酸甲酯(MeJA)处理对丹参(Salvia miltiorrhiza Bunge)幼苗叶片显微结构、叶片光合能力及幼苗中非结构糖积累的影响.结果显示:SA处理增加了丹参幼苗叶片气孔密度;叶肉细胞排列紧密、体积减小,叶肉细胞内叶绿体数目减少,但叶绿体体积增大,叶绿体基粒片层结构的数目增加;叶片中叶绿素a、b含量、叶气孔导度、蒸腾速率以及净光合速率均增加;同时,幼苗根中和叶片中酸性转化酶活性降低,幼苗地上部分蔗糖含量及可溶性糖总量显著高于对照.MeJA处理减少了叶片气孔密度,气孔发育畸形;叶肉细胞间隙增大,栅栏细胞层数减少,叶肉细胞内叶绿体数目减少,叶绿体体积减小,叶绿体基粒片层结构被破坏;叶片中叶绿素a及类胡萝卜素含量、叶片的净光合速率低于对照,叶气孔导度、蒸腾速率增强;同时,幼苗根中及叶中酸性转化酶活性增加,幼苗根中蔗糖含量及可溶性糖总量显著低于对照.可见,SA处理能促进植物叶片显微结构发育,增强叶片光合能力,抑制蔗糖降解并促进蔗糖积累;而MeJA处理则破坏了植物叶片显微结构,降低了叶片光合能力,促进了蔗糖降解并减少蔗糖积累.     

Effect of Drought Stress on Lipid Peroxidation,Osmotic Adjustment and Antioxidant Enzyme Activity of Leaves and Roots of <Emphasis Type="Italic">Lycium ruthenicum</Emphasis> Murr. Seedling

Seedling stage is a critical period for survival and growth under drought stress. In the current study, we determined effects of drought stress on physiological and biochemical parameters of leaves and roots of Lycium ruthenicum Murr. seedling. The variables measured were lipid peroxidation (in terms of malondialdehyde (MDA) content), osmotic substances (free proline, soluble protein, and soluble sugar), and antioxidative enzymes (peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT)). Free proline, soluble sugar, and MDA of leaves and roots increased with increasing stress level. Leaves displayed higher accumulations of free proline and MDA than roots. However, roots showed higher total soluble sugar than leaves. Under drought stress, soluble proteins in leaves and roots decreased initially and then increased. Meanwhile, measured proteins were higher in leaves. Under drought stress, SOD, POD, and CAT activities in leaves increased initially and then decreased but increased with increasing drought stress level in roots. Under drought the level of accumulation of osmotics was higher in the leaves than in the roots, while increased activity of antioxidant enzymes persisted in the stressed roots longer that in the leaves.     

纯化腐植酸对氮胁迫下黄瓜幼苗生长和氮代谢的影响

为研究纯化腐植酸(PHA)在不同水平氮胁迫下对黄瓜植株生长和氮代谢的影响,探明PHA对逆境胁迫的缓解作用机制,采用水培方式,选用新泰密刺为供试品种,以正常氮水平(11 mmol·L^-1 NO₃^-)为对照,进行低氮(1.0 mmol·L^-1 NO₃^-)和高氮(101 mmol·L^-1 NO₃^-)胁迫处理,研究纯化腐植酸对氮胁迫下黄瓜幼苗生长和氮代谢的影响.结果表明: 低氮和高氮胁迫均抑制了黄瓜幼苗生长,株高、茎粗、叶面积、干物质积累量均低于正常氮水平处理.施用纯化腐植酸促进了正常氮水平及低氮胁迫下黄瓜干物质积累,在高氮胁迫下差异不显著.PHA影响了黄瓜幼苗NO₃^-的吸收,呈低氮下促进、高氮下抑制吸收的趋势;PHA显著降低了低氮、高氮胁迫下根系和叶片中的铵态氮含量;与正常氮水平相比,低氮、高氮胁迫下根系和叶片的硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合酶(GOGAT)、谷氨酸脱氢酶(GDH)活性及根系中亚硝酸还原酶(NiR)活性均显著降低,PHA不同程度地提高了NR、NiR、GS、GOGAT、GDH活性,还提高了根系和叶片中游离氨基酸、可溶性蛋白的含量.综上,添加PHA缓解了氮胁迫对黄瓜幼苗生长的抑制作用.     

亚适温条件下缺铁和硝酸盐胁迫对番茄幼苗生长及铁吸收的影响

研究亚适温(昼/夜18 ℃/12 ℃)条件下缺铁和硝酸盐胁迫对番茄幼苗生长及铁吸收的影响.结果表明: 与适温对照相比,亚适温条件下番茄幼苗生长受到明显的抑制,株高、叶面积显著变小,干物质积累下降;亚适温下缺铁对番茄幼苗生长的影响比适温下缺铁的影响大.亚适温条件下,缺铁、硝酸盐胁迫及二者同时胁迫的番茄幼苗株高与无胁迫处理差异不显著,但幼苗叶面积明显变小,电解质渗漏率、根系活力和三价铁还原酶活性明显增加,叶绿素含量降低;根总长、根表面积、根体积及根尖数明显减小;幼苗根、茎、叶中铁含量明显降低.亚适温下硝酸盐胁迫以及缺铁与硝酸盐二者同时胁迫加重了番茄幼苗干物质积累的减少、电解质渗漏率的增加,以及减少了对铁离子的吸收.Fe²⁺对K⁺和Ca²⁺吸收具有拮抗作用,不同器官中的表现有所差异;降低营养液中的Fe²⁺浓度可使番茄幼苗的缺铁症状更加严重.     

Phosphorus distribution inside Chinese fir seedlings under different P supplies based on 32P tracer

通过分析杉木(Cunninghamia lanceolata)幼苗磷(P)分配规律, 可以阐明两个磷高效利用杉木在不同供磷水平下吸收外源磷的分配及动态变化, 为进一步进行磷高效利用基因型的选育提供参考。该研究以2个磷高效利用杉木家系(被动忍受型M1与主动活化型M4)幼苗为试验材料, 利用 ³²P同位素示踪技术, 研究在不同供磷水平下2个杉木家系幼苗磷分配规律。结果表明, M1和M4吸收的外源磷的含量分布特征均为根>叶>茎, 自显影中相同处理时期的各器官在水平投影面上 ³²P含量均为根>茎>叶。低磷处理下M1和M4根、茎、叶吸收的外源磷的含量均明显低于高磷处理, 自显影中相同处理时间根、茎、叶低磷水平下成像的黑化程度也低于高磷水平, 且低磷处理下吸收的外源磷的含量增加缓慢, 说明低磷胁迫严重影响杉木苗磷的吸收与积累。M1和M4的根系磷分配率在低磷胁迫下呈现出明显的先减少后增加趋势, 高磷水平下根系磷分配率表现为先增加后趋于平稳。这说明M1和M4可以通过体内磷的重新分配来适应外界低磷胁迫, 即杉木苗在低磷胁迫初期将根系中的磷转移至地上部分, 随着胁迫时间的延长, 地上部分的磷向根系中转移。但两个家系在低磷条件下对吸收的外源磷的分配格局差异明显: 从开始至结束M1吸收的外源磷的分配率表现为根系>地上部分, 而M4先表现为根系>地上部分, 后表现为地上部分>根系, 说明M1在低磷胁迫后加强体内磷循环的程度相比于M4更高, 即磷从地上部分向根系转移的趋势更强烈。     

盐胁迫下番茄砧木对嫁接苗生物量、氨基酸含量和活性氧代谢的影响

为探讨砧木对提高番茄嫁接苗耐盐性的作用机理,以耐盐性较敏感的‘中杂9号’(S)为接穗,耐盐性较强的‘OZ-006’(R)为砧木,采用劈接法形成嫁接苗(RS)以及接穗自嫁接苗(SS)、砧木自嫁接苗(RR)3个试验材料,在175 mmol·L^-1 NaCl处理下测定植株生长、Na⁺积累、氨基酸含量和活性氧代谢的变化。结果表明: NaCl胁迫导致番茄幼苗的盐害指数和Na⁺含量均显著提高,幼苗生长速率和叶绿素含量显著降低,但不同嫁接苗的类型差异显著,在盐害表型上表现为SS>RS>RR的规律。NaCl胁迫诱导嫁接苗的叶片和根系总氨基酸含量显著提高,其中RR、RS叶片有9种、根系有8种氨基酸含量显著高于对照,以脯氨酸含量变化最为显著,而SS叶片中仅有2种、根系中仅有4种氨基酸含量显著高于对照;幼苗间的氨基酸含量呈现RR>RS>SS的规律,RR、RS叶片的氨基酸含量分别比SS叶片上升了32.8%、16.6%,根系分别比SS上升了53.1%和32.5%。NaCl胁迫造成活性氧代谢的变化,幼苗叶片和根系的抗氧化酶活性、超氧阴离子产生速率、丙二醛含量均显著提高,以RR叶片和根系中抗氧化酶活性的增幅最大,其次为RS;SS和抗氧化酶活性的增幅最小,品种间活性氧水平表现为SS>RS>RR。综上,砧木通过抑制Na⁺向上运输、提高氨基酸水平和抗氧化酶活性缓解了盐胁迫对嫁接苗的伤害,但不同砧穗组合的耐盐性差异较大,以RR的耐盐性最强,其次为RS,SS最弱。因此,番茄嫁接苗的耐盐性主要受砧木耐盐性的影响,其次为接穗,同时,其与番茄体内的氨基酸和活性氧代谢调控密切相关。