外源一氧化氮对硝酸盐胁迫下黄瓜幼苗生长及抗氧化酶活性的影响

采用营养液培养试验,通过添加不同浓度(0.05、0.1、0.2、0. mmol·L^-1)的硝普钠（SNP）作为NO供体,研究外源NO对NO₃-胁迫下黄瓜幼苗生长及叶片抗氧化酶活性的影响.结果表明： 140 mmol·L^-1 NO₃-胁迫下,外加0.1 mmol·L^-1 SNP处理1 d和7 d后,黄瓜幼苗叶片中SOD、CAT和APX活性显著升高;MDA含量显著降低,可溶性蛋白含量增加,说明外加0.1 mmol·L^-1 SNP增强了黄瓜幼苗对活性氧的清除能力,降低了膜脂过氧化程度,幼苗生长势增加,对高浓度NO₃-胁迫的抗性增强;当SNP浓度达0.3 mmol·L^-1处理7 d后,SOD、POD、CAT和APX活性均开始降低,MDA含量增加,黄瓜幼苗受害加重.外加一定浓度(0.1～0.2 mmol·L^-1)的外源NO可缓解NO₃^-胁迫对黄瓜幼苗的影响.     

硅对连作黄瓜幼苗光合特性和抗氧化酶活性的影响

以‘津研四号’黄瓜品种为试材,研究了叶面喷施不同浓度硅(Si)(0、1、2、3、4、5 mmol·L^-1)对连作黄瓜幼苗生长、光合特性和抗氧化酶活性的影响.结果表明: 在一定浓度(1～3 mmol·L^-1 Si)范围内,施Si可降低幼苗叶片电解质渗漏率(EL)和丙二醛(MDA)含量;提高叶绿素a(Chl a)、叶绿素b(Chl b)、类胡萝卜素(Car)和总叶绿素含量,叶片净光合速率(P_n)升高;超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)和过氧化氢酶(CAT)活性均有所提高;黄瓜幼苗株高、茎粗、叶面积及干物质积累量增加.随施Si浓度的进一步增加(4～5 mmol·L^-1),叶片中EL和MDA含量升高,但仍低于对照;抗氧化酶活性和光合作用下降,幼苗生长受到显著抑制.说明外源Si可通过提高黄瓜幼苗叶片抗氧化酶活性来降低膜脂过氧化,通过增加光合作用来提高黄瓜幼苗长势,进而增强对连作障碍的抗性.以2 mmol·L^-1Si处理效果最好.     

Effects of root and foliar applications of exogenous NO on alleviating cadmium toxicity in lettuce seedlings

The effects of sodium nitroprusside (SNP, a donor of NO) on cadmium (Cd) toxicity in lettuce seedlings were studied. SNP was added into hydroponic systems or sprayed directly on the leaves of plants grown with and without Cd. Excess supply of Cd (100 μM) caused growth inhibition, dramatically increased Cd accumulation in both leaves and roots, and inhibited the absorption of Ca, Mg, Fe and Cu. Excess Cd also decreased activities of superoxide dismutase peroxidase and catalase in leaves and roots, and increased the accumulation of superoxide anion (O ₂ ^·? ), hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). Root or foliar applications of exogenous NO alleviated Cd-induced growth suppression, especially root application of 250 μM SNP and foliar addition of 500 μM SNP. Addition of SNP promoted the chlorophyll synthesis suggesting that the photosynthesis was up-regulated. Exogenous NO increased Cd-decreased activities of antioxidant enzymes and markedly diminished Cd-induced reactive oxygen species (ROS) and MDA accumulation. Moreover, the absorption of Ca, Mg, Fe and Cu was increased, indicating that exogenous NO stimulated H⁺-ATPase activity to promote sequestration or uptake of ions. In addition, exogenous NO also inhibited Cd transfer from roots to shoots, which may indicate that Cd retention in roots induced by NO plays a significant role in Cd tolerance in lettuce seedlings. These data suggest that under Cd stress, exogenous NO improves photosynthesis by increasing chlorophyll synthesis, protects lettuce seedlings against oxidative damage by scavenging ROS, helps to maintain the uptake of nutrient elements, and inhibits Cd transferred to shoots effectively.     

外源一氧化氮对盐胁迫下黑麦草幼苗生长及生理特性的影响

研究了外源一氧化氮（nitric oxide,NO）对盐胁迫下多年生黑麦草幼苗生长及相关生理指标变化的影响。结果表明,与对照相比,50～200μmol·L-1NO供体硝普钠（sodium nitroprusside,SNP）可缓解盐胁迫对黑麦草幼苗生长的抑制作用,其中100μmo·lL-1SNP缓解作用最强。外施SNP显著缓解了盐胁迫导致的叶片相对电导率、K＋与Na＋比率、丙二醛含量和活性氧水平的增加,提高了盐胁迫下幼苗叶子中脯氨酸含量和超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化物酶和过氧化物酶等抗氧化酶的活性。这些结果说明,NO可能通过降低细胞吸收Na＋的量、增加细胞吸收K＋的量和脯氨酸含量以及激活抗氧化保护酶等减轻了盐对黑麦草的伤害,提高了黑麦草的抗盐性。     

Effects of nitric oxide on the germination of cucumber seeds and antioxidant enzymes under salinity stress

Effects of exogenous nitric oxide (NO) on the germination and antioxidant enzyme during cucumber seed germination were investigated under salt stress. Seeds of cucumber (Cucumis sativus L. cv. Jinyou 1) were treated with distilled water or NaCl in the presence or absence of NO donor sodium nitroprusside (SNP) during germination. Excess 50 mM NaCl reduced significantly the seed germination rate in a short term and speed of germination. When salt concentration increased, germination of cucumber seed was reduced and the time needed to complete germination lengthened. Addition of exogenous SNP in salt solution attenuated the salt stress effects in a dose-dependent manner, as indicated by accelerating the seed germination, as well as weight increase of budding seeds, and 50 μM SNP was optimal concentration. At 150 mM NaCl, the 50 μM exogenous SNP significantly increased the activities of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and protein content, while decreased the contents of malondialdehyde (MDA). There were no obvious effects of exogenous NO on peroxidase (POD, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.6) activities under salt stress. Exogenous NO also increased the SOD and CAT isozyme expression under salt stress, which was in accordance with the improved antioxidant activities in the germinating seeds. The NO-induced salt stress resistance was associated with activated enzymes, and enhanced protein content, thus decreasing MDA content. It is concluded that exogenous NO treatment on cucumber seeds may be a good option to improve seed germination under saline conditions.     

Physiological and biochemical roles of nitric oxide against toxicity produced by glyphosate herbicide in <Emphasis Type="Italic">Pisum sativum</Emphasis>

The present study assessed the response of pea plants exposed to herbicide induced oxidative stress in the plants present in agriculture field. We analysed the effect of exogenous nitric oxide (NO) regulated chlorophyll and protein content, nitrate reductase enzyme activity and antioxidant enzyme activity in herbicidetreated green pea (Pisum sativum L.). Glyphosate (0.25 mM) treatment alone or in combination with 250 μM sodium nitroprusside (SNP, 250 μM with glyphosate) was given to pea and we observed the changes in biophysical and biochemical parameters. During oxidative stress ion leakage is the first step of cellular damage. Supplementation of SNP with glyphosate significantly reduced ion leakage and moderately reduced H2O2 and malondialdehyde (MDA) content. SNP also increased chlorophyll content and antioxidant enzymes viz. superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (POD) activity as compared to herbicide treatment alone. The present result suggests that NO protects pea plants from damage caused by glyphosate.     

Effects of exogenous nitric oxide on photosynthesis,antioxidative ability,and mineral element contents of perennial ryegrass under copper stress

A hydroponics experiment was conducted to test the effects of sodium nitroprusside (SNP, a donor of NO) supplied with different concentrations on copper (Cu) toxicity in ryegrass seedlings (Lolium perenne L.). Excess Cu (200 µM) reduced chlorophyll content, resulting a decrease in photosynthesis. Cu stress induced the production of hydrogen peroxide (H₂O₂) and superoxide anion (O₂^{? ?}), leading to malondialdehyde (MDA) accumulation. Furthermore, activities of antioxidant enzymes in Cu-treated seedlings such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were decreased. In addition, Cu stress inhibited the uptake of K, Mg, Fe, and Zn and increased Ca content in roots. Moreover, in leaves of Cu-stressed seedlings, K, Fe, and Zn contents were decreased and the contents of Ca and Mg were not affected significantly. In Cu-treated seedlings, Cu concentration in roots was higher than in leaves. Addition of 50, 100, 200 µM SNP in Cu-mediated solutions increased chlorophyll content and photosynthesis, improved antioxidant enzyme activities, reduced Cu-induced oxidative damages, kept intracellular ion equilibrium under Cu stress, increased Cu concentration in roots and inhibited Cu accumulation in leaves. In particular, addition of 100 µM SNP had the best effect on promoting growth of ryegrass seedlings under Cu stress. However, the application of 400 µM SNP had no obvious alleviating effect on Cu toxicity in ryegrass seedlings.     

Glutathione-Mediated Alleviation of Chromium Toxicity in Rice Plants

A hydroponic experiment was conducted to determine the possible effect of exogenous glutathione (GSH) in alleviating chromium (Cr) stress through examining plant growth, chlorophyll contents, antioxidant enzyme activity, and lipid peroxidation in rice seedlings exposed to Cr toxicity. The results showed that plant growth and chlorophyll content were dramatically reduced when rice plants were exposed to 100 μM Cr. Addition of GSH in the culture solution obviously alleviated the reduction of plant growth and chlorophyll content. The activities of some antioxidant enzymes, including superoxide dismutase, catalase (CAT) and glutathione reductase in leaves, and CAT and glutathione peroxidase in roots showed obvious increase under Cr stress. Addition of GSH reduced malondialdehyde accumulation and increased the activities of these antioxidant enzymes in both leaves and roots, suggesting that GSH may enhance antioxidant capacity in Cr-stressed plants. Furthermore, exogenous GSH caused significant decrease of Cr uptake and root-to-shoot transport in the Cr-stressed rice plants. It can be assumed that GSH is involved in Cr compartmentalization in root cells.     

丝瓜作砧木提高黄瓜耐涝性的研究

研究了涝害胁迫下黄瓜自根苗、南瓜砧嫁接苗和丝瓜砧嫁接苗的耐涝性能。结果表明：涝害胁迫时,丝瓜砧嫁接苗能维持较高的根系活力与较高的叶绿素含量;根系电解质渗出率、丙二醛（MDA）含量和超氧阴离子自由基（O2-）的含量 显著低于黄瓜自根苗和南瓜砧嫁接苗;根系SOD、POD和CAT等细胞保护酶活性高于黄瓜自根苗和南瓜砧嫁接苗;丝瓜作砧木可以提高黄瓜的耐涝性。     

丝瓜作砧木提高黄瓜耐涝性的研究

研究了涝害胁迫下黄瓜自根苗、南瓜砧嫁接苗和丝瓜砧嫁接苗的耐涝性能。结果表明：涝害胁迫时,丝瓜砧嫁接苗能维持较高的根系活力与较高的叶绿素含量;根系电解质渗出率、丙二醛(MDA)含量和超氧阴离子自由基(O2^-)的含量显著低于黄瓜自根苗和南瓜砧嫁接苗;根系SOD、POD和CAT等细胞保护酶活性高于黄瓜自根苗和南瓜砧嫁接苗;丝瓜作砧木可以提高黄瓜的耐涝性。     

Cinnamic acid pretreatment mitigates chilling stress of cucumber leaves through altering antioxidant enzyme activity

To elucidate the physiological mechanism of chilling stress mitigated by cinnamic acid (CA) pretreatment, a cucumber variety (Cucumis sativus cv. Jinchun no. 4) was pretreated with 50 μM CA for 2 d and was then cultivated at two temperatures (15/8 and 25/18 °C) for 1 d. We investigated whether exogenous CA could protect cucumber plantlets from chilling stress (15/8 °C) and examined whether the protective effect was associated with the regulation of antioxidant enzymes and lipid peroxidation. At 2 d, exogenous CA did not influence plant growth, but induced the activities of some antioxidant enzymes, including superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), guaiacol peroxidase (GPX, EC 1.11.1.7), glutathione peroxidase (GSH-Px, EC 1.6.4.2) and ascorbate peroxidase (APX, EC 1.11.1.11) in cucumber leaves, and it also elevated the contents of reduced glutathione (GSH) and ascorbate (AsA). When CA was rinsed and the CA-pretreated seedlings were exposed to different temperatures, the antioxidant activities in leaves at 3 d had undergone additional change. Chilling increased the activities of CAT, GSH-PX, APX, GSH and AsA in leaves, but the combination of CA pretreatment and chilling enhanced the antioxidant activities even more. Moreover, chilling inhibited plant growth and increased the contents of malonaldehyde (MDA), superoxide radical (O₂⁻) and hydrogen peroxide (H₂O₂) in cucumber leaves, and the stress resulted in 87.5% of the second leaves being withered. When CA pretreatment was combined with the chilling stress, we observed alleviated growth inhibition and decreased contents of MDA, H₂O₂ and O₂⁻ in comparison to non-pretreated stressed plants, and found that the withered leaves occurred at a rate of 25.0%. We propose that CA pretreatment increases antioxidant enzyme activities in chilling-stressed leaves and decreases lipid peroxidation to some extent, enhancing the tolerance of cucumber leaves to chilling stress.     

外源一氧化氮对镉胁迫下绿豆幼苗根尖抗氧化酶的影响

采用水培法研究外源一氧化氮对镉(Cd)胁迫下绿豆幼苗根尖抗氧化酶活性的影响。结果表明:0.01mmol/L和0.1mmol/L一氧化氮供体硝普钠(sodium nitroprusside,SNP)显著促进上胚轴生长,1mmol/LSNP则抑制绿豆幼苗生长。Cd单独处理抑制根尖抗坏血酸过氧化物酶(ascorbate peroxidase,APX)和超氧化物歧化酶(superoxide dismutase,SOD)活性而刺激脂氧合酶(lipoxygenase,LOX)、谷胱甘肽转硫酶(glutathione S-transferase,GST)、谷胱甘肽还原酶(glutathione reductase,GR)和过氧化物酶(guaiacol peroxidase,POD)活性上升。0.1mmol/LSNP预处理能够明显缓解Cd对根生长的抑制,降低根尖中MDA含量,提高根尖APX和SOD活性,降低LOX和POD活性,但不影响GST和GR活性。     

氯化胆碱对盐胁迫黄瓜幼苗渗透调节物质及活性氧代谢系统的影响

以盐敏感型黄瓜品种津春4号为材料,采用水培方法研究了叶面喷施不同浓度(0.5、1.0和1.5 mmol·L-1)氯化胆碱(CC)对NaCl胁迫(75 mmol·L-1)下黄瓜幼苗鲜重、叶片叶绿素、渗透调节物质含量及活性氧代谢系统的影响.结果表明:(1)单独CC处理可提高黄瓜叶片的叶绿素、可溶性糖和可溶性蛋白含量以及过氧化氢酶(CAT)与过氧化物酶(POD)活性,降低O2·-产生速率,但对植株鲜重及超氧化物岐化酶(SOD)活性影响不大;(2)NaCl胁迫处理增加了黄瓜幼苗叶片中可溶性糖和可溶性蛋白含量,增强了SOD、POD和CAT活性,提高了O2·-产生速率及丙二醛(MDA)的含量,但同时降低了叶绿素含量与植株鲜重;(3)盐胁迫前CC预处理可缓解黄瓜幼苗叶绿素含量和植株鲜重的下降、以及MDA含量和O2·-产生速率的上升趋势,且进一步提高了盐胁迫下黄瓜叶片中SOD、POD和CAT活性.因此,适宜浓度的氯化胆碱可显著提高盐胁迫下黄瓜叶片的抗氧化酶活性,提高清除活性氧的能力,缓解盐胁迫对黄瓜幼苗细胞膜的伤害,增强黄瓜幼苗的耐盐性.     

Exogenous sodium nitroprusside and glutathione alleviate copper toxicity by reducing copper uptake and oxidative damage in rice (Oryza sativa L.) seedlings

Nitric oxide (NO) and glutathione (GSH) regulate a variety of physiological processes and stress responses; however, their involvement in mitigating Cu toxicity in plants has not been extensively studied. This study investigated the interactive effect of exogenous sodium nitroprusside (SNP) and GSH on Cu homeostasis and Cu-induced oxidative damage in rice seedlings. Hydroponically grown 12-day-old seedlings were subjected to 100 μM CuSO₄ alone and in combination with 200 μM SNP (an NO donor) and 200 μM GSH. Cu exposure for 48 h resulted in toxicity symptoms such as stunted growth, chlorosis, and rolling in leaves. Cu toxicity was also manifested by a sharp increase in lipoxygenase (LOX) activity, lipid peroxidation (MDA), hydrogen peroxide (H₂O₂), proline (Pro) content, and rapid reductions in biomass, chlorophyll (Chl), and relative water content (RWC). Cu-caused oxidative stress was evident by overaccumulation of reactive oxygen species (ROS; superoxide (O₂ ^?–) and H₂O₂). Ascorbate (AsA) content decreased while GSH and phytochelatin (PC) content increased significantly in Cu-stressed seedlings. Exogenous SNP, GSH, or SNP?+?GSH decreased toxicity symptoms and diminished a Cu-induced increase in LOX activity, O₂ ^?–, H₂O₂, MDA, and Pro content. They also counteracted a Cu-induced increase in superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and glyoxalase I and glyoxalase II activities, which paralleled changes in ROS and MDA levels. These seedlings also showed a significant increase in catalase (CAT), glutathione peroxidase (GPX), dehydroascorbate reductase (DHAR), glutathione S-transferase (GST) activities, and AsA and PC content compared with the seedlings stressed with Cu alone. Cu analysis revealed that SNP and GSH restricted the accumulation of Cu in the roots and leaves of Cu-stressed seedlings. Our results suggest that Cu exposure provoked an oxidative burden while reduced Cu uptake and modulating the antioxidant defense and glyoxalase systems by adding SNP and GSH play an important role in alleviating Cu toxicity. Furthermore, the protective action of GSH and SNP?+?GSH was more efficient than SNP alone.     

5-Aminolevulinic acid enhances photosynthetic gas exchange, chlorophyll fluorescence and antioxidant system in oilseed rape under drought stress

This study evaluates the role of exogenous foliar application of 5-aminolevulinic acid (ALA) on water relations, gas exchange, chlorophyll fluorescence, and the activities and gene expression patterns of antioxidant enzymes in leaves of oilseed rape under drought stress and recovery conditions. Seedlings at four-leaf stage were imposed to well-watered condition (80 % of water-holding capacity) or drought stress (40 % of water-holding capacity) and subsequently foliar sprayed with water or ALA (30 mg l^?1). Drought suppressed the accumulation of plant biomass and decreased chlorophyll content and leaf water status (relative water content and water potential). The actual quantum yield of photosystem II and electron transport rates were hampered in parallel to net photosynthetic rate. However, drought stress induced the accumulation of malondialdehyde (MDA) and hydrogen peroxide, enhanced the activities of catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR) and superoxide dismutase and up-regulated the expression of APX and GR. After rehydration for 4 days, the growth of drought-treated seedlings was restored to normal level for most of the physiological parameters. Foliar application of ALA maintained relatively higher leaf water status and enhanced chlorophyll content, net photosynthetic rate, actual quantum yield of photosystem II, photochemical quenching, non-photochemical quenching and electron transport rates in stressed leaves. Exogenous ALA also alleviated the accumulation of MDA and hydrogen peroxide, increased the activities of antioxidant enzymes and enhanced the expression of CAT and POD in drought-treated plants. These results indicate that ALA may effectively protect rapeseed seedlings from damage induced by drought stress.     

Stress responses of wheat leaves to dehydration: Participation of endogenous NO and effect of sodium nitroprusside

Dynamics of endogenous NO in the leaves of 7-day-old seedlings of spring wheat (Triticum aestivum L., cv. Debyut) and the effect of exogenous NO donor (sodium nitroprusside, SNP) on the development of oxidative stress and activity of antioxidant enzymes in the leaves under water deficiency were investigated. Quick and phasic accumulation of NO in the leaves was observed under growing dehydration (0–3 h) and subsequent rehydration (0–3 h), which points to identical response of NO signal system to opposite changes in the water status of plants. A decrease in relative turgidity of tissues brought about accumulation of H₂O₂ and MDA therein. Protective effect of NO donor infiltrated in the leaves was associated with an elevation of ascorbate peroxidase and catalase activities and suppression of lipid peroxidation upon dehydration. Pretreatment with SNP (50–250 μM) induced the elevation of NO level in the leaves both before action of the stress agent and in the beginning (0–30 min) of dehydration. The obtained results suggest that brief increase in endogenous NO is necessary for triggering protective and adaptive responses in wheat plants during the development of water deficiency.     

外源亚精胺对根际低氧胁迫下黄瓜幼苗根系多胺含量和抗氧化酶活性的影响

采用营养液水培,研究了根际低氧胁迫下外源亚精胺对两个抗低氧能力不同的黄瓜(Cucumis sativus)品种(‘中农8号’和‘绿霸春4号’)根系中多胺含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的影响。结果表明,外源亚精胺能显著提高低氧胁迫下黄瓜幼苗根系中亚精胺和精胺含量,降低腐胺含量,同时,根系中SOD、POD、CAT活性也相应提高,使得幼苗鲜重和干重明显增加;单纯低氧处理及外源亚精胺的加入,抗低氧能力较强的品种‘绿霸春4号’较抗低氧能力较弱的品种‘中农8号’根系中抗氧化酶活性高。黄瓜幼苗根系中较高的亚精胺、精胺含量和较低的腐胺含量可能有利于提高抗氧化酶活性,增强幼苗的低氧逆境适应能力。     

28-homobrassinolide improves growth and photosynthesis in <Emphasis Type="Italic">Cucumis sativus</Emphasis> L. through an enhanced antioxidant system in the presence of chilling stress

The ameliorative role of 28-homobrassinolide under chilling stress in various growth, photosynthesis, enzymes and biochemical parameters of cucumber (Cucumis sativus L.) were investigated. Cucumber seedlings were sprayed with 0 (control), 10⁻⁸, or 10⁻⁶ M of 28-homobrassinolide at the 30-day stage. 48 h after treatment plants were exposed for 18 h to chilling temperature (10/8°C, 5/3°C). The most evident effect of chilling stress was the marked reduction in plant growth, chlorophyll (Chl) content, and net photosynthetic rate, efficiency of photosystem II and activities of nitrate reductase and carbonic anhydrase. Moreover, the activities of antioxidant enzymes; catalase (E.C. 1.11.1.6), peroxidase (E.C.1.11.1.7), superoxide dismutase (E.C. 1.15.1.1) along with the proline content in leaves of the cucumber seedlings increased in proportion to chilling temperature. The stressed seedlings of cucumber pretreated with 28-homobrassinolide maintained a higher value of antioxidant enzymes and proline content over the control suggesting the protective mechanism against the ill-effect caused by chilling stress might be operative through an improved antioxidant system. Furthermore, the protective role of 28-homobrassinolide was reflected in improved growth, water relations, photosynthesis and maximum quantum yield of photosystem II both in the presence and absence of chilling stress.     

外源NO对南方红豆杉幼苗光合色素及抗氧化酶的影响

以4年生南方红豆杉幼苗为实验材料,通过对南方红豆杉幼苗喷施不同浓度外源一氧化氮（NO）供体硝普钠溶液（0、0.01、0.1、0.5和1 mmol·L^-1SNP）,测定光合色素含量、抗氧化酶活性、丙二醛（MDA）含量和过氧化氢（H₂O₂）含量等生理指标,以探讨不同浓度外源NO对南方红豆杉叶片光合色素和抗氧化酶的影响。结果表明：喷施低浓度（0.01、0.1 mmol·L^-1）SNP可显著提高南方红豆杉叶片的叶绿素a、叶绿素b、类胡萝卜素和总叶绿素含量,增加叶绿素a/b的比值,而喷施高浓度（0.5、1 mmol·L^-1）SNP降低了叶片的光合色素含量。随着外源NO供体浓度的增加,叶片过氧化氢酶(CAT)活性显著增加,过氧化物酶(POD)活性先增加后降低。此外,处理前期,低浓度SNP处理明显提高了抗坏血酸过氧化物酶(APX)活性,而高浓度SNP处理显著降低了APX活性,处理后期APX活性随SNP浓度的增加而显著下降。喷施低浓度SNP可有效提高超氧化物歧化酶(SOD)活性和增加可溶性蛋白含量,降低MDA和H₂O₂的含量,而喷施高浓度SNP显著增加了MDA和H₂O₂的含量。因此,低浓度的SNP（<0.5 mmol·L^-1）处理南方红豆杉幼苗,可增加其叶绿素含量,提高抗氧化酶活性,降低MDA和H₂O₂的含量,而高浓度的SNP（≥0.5 mmol·L^-1）处理会降低叶绿素含量,提高H₂O₂含量,增加细胞膜质过氧化程度,从而对南方红豆杉幼苗造成一定伤害。