Efficacy of foliar extracts against pre- and post-harvest diseases of sponge-gourd fruits

S.K. AHMAD AND J.S. PRASAD. 1995. The inhibitory potential of aqueous foliar extracts of Adhatoda vasica, Azadirachta indica, Catharanthes roseus, Datura fistulosa, Lantana camara, Muraya exotica, Ocimum sanctum, Ricinus communis and Strychnos nux-vomica were evaluated against soft rot diseases of sponge-gourd fruits caused by Helminthosporium spiciferum and Fusarium scirpi. Conidial germination of F. scirpi and H. spiciferum were reduced to about 75% when their spores were treated with A. indica, C. roseus, D. fistulosa, L. camara, M. exotica and O. sanctum. Considerable reductions (50%) in mycelial dry weights and colony diameters were recorded in liquid media containing (20%) aqueous extracts of C. roseus, D. fistulosa and M. exotica . Other extracts reduced the mycelial growth but to a lesser extent. Post-infection treatment of sponge-gourd fruits with the extracts of A. indica, L. camara, M. exotica, O. sanctum, D. fistulosa and C. roseus almost fully inhibited the spread of disease. Treatment of fruits with A. indica and C. roseus before fungal infection reduced the spread of disease caused by both the pathogens, whereas M. exotica, O. sanctum and D. fistulosa reduced the spread of soft-rot caused by F. scirpi but not by H. spiciferum .     

Efficacy of leaf extracts of some medicinal plants against disease development in banana

Treatment of infested banana fruits by aqueous leaf extracts of some medicinal plants, viz. Calotropis procera (Ait) R.Br., Vitex negundo Linn., Lantana camara Linn., Azadirachta indica Linn., Ficus religiosa Linn., Ocimum sanctum Lin., Thuja orientalis Linn., Argemone mexicana Linn., Achyranthes aspera Linn., Datura fastuosa Linn. and Ricinus communis Linn. exhibited considerable control of disease development. Of 11 leaf extracts, those of A. indica and O. sanctum were most effective, and showed minimum per cent loss in fruit weight. The appearance of the first disease symptom was also delayed in treated fruits as compared with untreated ones.     

Arsenite treatment induces oxidative stress,upregulates antioxidant system,and causes phytochelatin synthesis in rice seedlings

The effects of arsenite treatment on generation of reactive oxygen species, induction of oxidative stress, response of antioxidative system, and synthesis of phytochelatins were investigated in two indica rice (Oryza sativa L.) cvs. Malviya-36 and Pant-12 grown in sand cultures for a period of 5–20 days. Arsenite (As₂O₃; 25 and 50 μM) treatment resulted in increased formation of superoxide anion (O₂^.−), elevated levels of H₂O₂ and thiobarbituric acid reactive substances, showing enhanced lipid peroxidation. An enhanced level of ascorbate (AA) and glutathione (GSH) was observed irrespective of the variation in the level of dehydroascorbate (DHA) and oxidized glutathione (GSSG) which in turn influenced redox ratios AA/DHA and GSH/GSSG. With progressive arsenite treatment, synthesis of total acid soluble thiols and phytochelatins (PC) increased in the seedlings. Among antioxidative enzymes, the activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), total ascorbate peroxidase (APX, EC 1.11.1.11), chloroplastic ascorbate peroxidase, guaiacol peroxidase (EC 1.11.1.7), monodehydroascorbate reductase (EC 1.6.5.4), and glutathione reductase (EC 1.6.4.2) increased in arsenite treated seedlings, while dehyroascorbate reductase (EC 1.8.5.1) activity declined initially during 5–10 days and increased thereafter. Results suggest that arsenite treatment causes oxidative stress in rice seedlings, increases the levels of many enzymatic and non-enzymatic antioxidants, and induces synthesis of thiols and PCs, which may serve as important components in mitigating arsenite-induced oxidative damage.     

Involvement of oxidative stress and role of antioxidative defense system in growing rice seedlings exposed to toxic concentrations of aluminum

When seedlings of rice (Oryza sativa L.) cultivar Pant-12 were raised in sand cultures containing 80 and 160 μM Al³⁺ in the medium for 5–20 days, a regular increase in Al³⁺ uptake with a concomitant decrease in the length of roots as well as shoots was observed. Al³⁺ treatment of 160 μM resulted in increased generation of superoxide anion (O₂ ⁻) and hydrogen peroxide (H₂O₂), elevated amount of malondialdehyde, soluble protein and oxidized glutathione and decline in the concentrations of thiols (-SH) and ascorbic acid. Among antioxidative enzymes, activities of superoxide dismutase (SOD EC 1.15.1.1), guaiacol peroxidase (Guaiacol POX EC 1.11.1.7), ascorbate peroxidase (APX EC 1.11.1.11), monodehydroascorbate reductase (MDHAR EC 1.6.5.4), dehydroascorbate reductase (EC 1.8.5.1) and glutathione reductase (EC 1.6.4.2) increased significantly, whereas the activities of catalase (EC EC 1.11.1.6) and chloroplastic APX declined in 160 μM Al³⁺ stressed seedlings as compared to control seedlings. The results suggest that Al³⁺ toxicity is associated with induction of oxidative stress in rice plants and among antioxidative enzymes SOD, Guaiacol POX and cytosolic APX appear to serve as important components of an antioxidative defense mechanism under Al³⁺ toxicity. PAGE analysis confirmed the increased activity as well as appearance of new isoenzymes of APX in Al³⁺ stressed seedlings. Immunoblot analysis revealed that changes in the activities of APX are due to changes in the amounts of enzyme protein. Similar findings were obtained when the experiments were repeated using another popular rice cv. Malviya-36.     

Drought Induces Oxidative Stress and Enhances the Activities of Antioxidant Enzymes in Growing Rice Seedlings

When rice seedlings grown for 10 and 20 days were subjected to in vitro drought stress of −0.5 and −2.0 MPa for 24 h, an increase in the concentration of superoxide anion (O₂^.−), increased level of lipid peroxidation and a decrease in the concentration of total soluble protein and thiols was observed in stressed seedlings compared to controls. The concentration of H₂O₂ as well as ascorbic acid declined with imposition of drought stress, however glutathione (GSH) concentration declined only under severe drought stress. The activities of total superoxide dismutases (SODs) as well as ascorbate peroxidase (APX) showed consistent increases with increasing levels of drought stress, however catalase activity declined. Mild drought stressed plants had higher guaiacol peroxidase (GPX) and chloroplastic ascorbate peroxidase (c-APX) activity than control grown plants but the activity declined at the higher level of drought stress. The activities of enzymes involved in regeneration of ascorbate i.e. monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were higher in drought stressed plants compared to controls. Results suggest that drought stress induces oxidative stress in rice plants and that besides SOD, the enzymes of ascorbate-glutathione cycle, which have not been studied in detail earlier under stressful conditions, appear to function as important component of antioxidative defense system under drought stress.     

Nickel-induced oxidative stress and the role of antioxidant defence in rice seedlings

Seedlings of rice (Oryza sativa L.) cv. Pant-12 grown in sand cultures containing 200 and 400 μM NiSO₄, showed a decrease in length and fresh weight of roots and shoots. Nickel was readily taken up by rice seedlings and the concentration was higher in roots than shoots. Nickel-treated seedlings showed increased rates of superoxide anion (O₂ ^•− ) production, elevated levels of H₂O₂ and thiobarbituric acid reactive substances (TBARS) demonstrating enhanced lipid peroxidation, and a decline in protein thiol levels indicative of increased protein oxidation compared to controls. With progressively higher Ni concentrations, non-protein thiol and ascorbate (AsA) increased, whereas the level of low-molecular-weight thiols (such as glutathione and hydroxyl-methyl glutathione), the ratio of these thiols to their corresponding disulphides, and the ratio of AsA to dehydroascorbic acid declined in the seedlings. Among the antioxidant enzymes studied, the activities of all isoforms of superoxide dismutase (Cu-Zn SOD, Mn SOD and Fe SOD), guaiacol peroxidases (GPX) and ascorbate peroxidase (APX) increased in Ni-treated seedlings, while no clear alteration in catalase activity was evident. Activity of the ascorbate-glutathione cycle enzymes monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR)—significantly increased in Ni-treated seedlings. However such increase was apparently insufficient to maintain the intracellular redox balance. Results suggest that Ni induces oxidative stress in rice plants, resulting in enhanced lipid peroxidation and decline in protein thiol levels, and that (hydroxyl-methyl) glutathione and AsA in conjunction with Cu-Zn SOD, GPX and APX are involved in stress response.     

Mitochondrial malate dehydrogenase and malic enzyme of a filarial worm Setaria digitata: some properties and effects of drugs and herbal extracts.

Mitochondrial malate dehydrogenase (mMDH) and malic enzyme (mME) of a filarial worm Setaria digitata were studied. mMDH exhibited the highest activities in the oxidation and reduction reactions at pH 9.5 and pH 6.2, respectively, while mME did so in the malate decarboxylation reaction at pH 6.8. mME showed no detectable activity on the pyruvate carboxylation direction. The Km values for malate (1.7 mM) and oxaloacetate (0.17 mM) and the ratio of Vmax oxidation: Vmax reduction (2.73) tend to favor the oxaloacetate reduction by mMDH. mME showed a relatively high Km value of 8.3 mM, for malate decarboxylation. A drug, diethylcarbamazine citrate (DEC-C), did not change appreciably the activity of either mMDH or mME, while filarin (a drug of herbal origin) effectively inhibited mMDH. The leaf extracts of Ocimum sanctum, Lawsonia inermis and Calotropis gigantea and leaf and flower extracts of Azadirachta indica were, however, found to inhibit both mMDH and mME.     

Effect of nitrogen deficiency on antioxidant status and Cd toxicity in rice seedlings

Effect of nitrogen (N) deficiency on antioxidant status and Cd toxicity in rice seedlings was investigated. N deficiency resulted in a reduction of shoot growth but not root growth. The contents of N-containing compounds such as nitrate, chlorophyll, and protein decreased in leaves of rice seedlings grown under N deficiency. Accumulation of abscisic acid and H₂O₂ in leaves was induced by N deficiency. The content of ascorbate and the activities of ascorbate peroxidase, glutathione reductase, and catalase in N-deficient leaves were lower than their respective control leaves. However, glutathione content was not affected and superoxide dismutase activity was increased by N deficiency. Cd toxicity in N-deficient seedlings was more pronounced than that in N-sufficient ones. Pretreatment with ascorbate or L-galactono-1,4-lactone, a biosynthetic precursor of ascorbate resulted in a reduction of Cd toxicity enhanced by N deficiency. N deficiency also resulted in an enhancement of Cd uptake in rice seedlings. The possible mechanism of Cd toxicity enhanced by N deficiency is discussed.     

Anti-inflammatory,anti-oxidant effect and cytotoxicity of ocimum sanctum intra oral gel for combating periodontal diseases

It is of interest to evaluate the anti-inflammatory, anti-oxidant effect and cytotoxicity of Ocimum sanctum (an Indian herb, Thulsi) intra oral gel in combating periodontal diseases. Hence, 2% of O. sanctum gel was prepared with Carbopol940 soaked in purified water containing 0.2% w/v sodium benzoate overnight. Hydroxy proplyl methyl cellulose (HPMC) solution was mixed with propylene glycol using using tissue homogenizer. Anti-oxidant effect was analyzed using DPPH radical assay and anti-inflammatory effect was assessed using the inhibition of albumin denaturation assay. Ocimum sanctum gel with various dilutions from10 micro litres to 50 micro litres showed exponential increase in percentage of inhibition from 60.9 to 72.2 exhibiting antioxidant activity. The anti-inflammatory effect of Ocimum sanctum gel showed comparatively equivalent effect with standard diclofenac gel with values ranging from 76.6 for 50 micro liters of Ocimum sanctum gel and 89.6 for standard gel at 50 micro liters. Ocimum sanctum showed less toxicity towards brine shrimp nauplii. Thus we show that Ocimum sanctum gel showed potent anti-oxidant and anti-inflammatory effect and less toxic to brine shrimp nauplii as a promising agent for the treatment of periodontal diseases.     

Manganese-excess induces oxidative stress,lowers the pool of antioxidants and elevates activities of key antioxidative enzymes in rice seedlings

Manganese (Mn) is an essential element for plant growth but in excess, specially in acidic soils, it can become phytotoxic. In order to investigate whether oxidative stress is associated with the expression of Mn toxicity during early seedling establishment of rice plants, we examined the changes in the level of reactive oxygen species (ROS), oxidative stress induced an alteration in the level of non-enzymic antioxidants and activities of antioxidative enzymes in rice seedlings grown in sand cultures containing 3 and 6 mM MnCl₂. Mn treatment inhibited growth of rice seedlings, the metal increasingly accumulated in roots and shoots and caused damage to membranes. Mn treated plants showed increased generation of superoxide anion (O₂ ^.−), elevated levels of H₂O₂ and thiobarbituric acid reactive substances (TBARS) and decline in protein thiol. The level of nonprotein thiol, however, increased due to Mn treatment. A decline in contents of reduced ascorbate (AsA) and glutathione (GSH) as well as decline in ratios of their reduced to oxidize forms was observed in Mn-treated seedlings. The activities of antioxidative enzymes superoxide dismutase (SOD) and its isoforms Mn SOD, Cu/Zn SOD, Fe SOD as well as guaiacol peroxidase (GPX) increased in the seedlings due to Mn treatment however, catalase (CAT) activity increased in 10 days old seedlings but it declined by 20 days under Mn treatment. The enzymes of Halliwell-Asada cycle, ascorbate peroxidase (APX) monodehydoascorbate reductase (MDHAR), dehyroascorbate reductase (DHAR) and glutathione reductase (GR) increased significantly in Mn treated seedlings over controls. Results suggest that in rice seedlings excess Mn induces oxidative stress, imbalances the levels of antioxidants and the antioxidative enzymes SOD, GPX, APX and GR appear to play an important role in scavenging ROS and withstanding oxidative stress induced by Mn.     

Protective effect of Ocimum sanctum L after high-dose 131iodine exposure in mice: an in vivo study

Radioprotective effect of aqueous extract of Ocimum sanctum (40 mg/kg body weight, for 15 days) in mice exposed to high-doses (3.7 MBq) of oral 131iodine was investigated by studying the organ weights, lipid peroxidation and antioxidant defense enzymes in various target organs like liver, kidneys, salivary glands and stomach at 24 hr after exposure in adult Swiss mice. The mean weight of the salivary glands showed significant increase after 131iodine administration. 131iodine exposure significantly increased lipid peroxidation in kidneys and salivary glands in comparison to control animals. Pretreatment with O. sanctum in radioiodine exposed group showed significant reduction in lipid peroxidation in both kidneys and salivary glands. In liver, reduced glutathione (GSH) levels showed significant reduction after radioiodine exposure while pretreatment with O. sanctum exhibited less depletion in GSH level even after 131iodine exposure. However, no such changes were observed in stomach. The results indicate the possibility of using aqueous extract of O. sanctum for ameliorating 131Iodine induced damage to the salivary glands.     

Effect of maternal fluoride exposure on developing CNS of rats: protective role of Aloe vera, Curcuma longa and Ocimum sanctum

Fluoride is toxic to neuronal development and its excessive intake during pregnancy cause adverse effects on neonatal development. The present study examined the presence of oxidative stress during maternal exposure of fluoride and the therapeutic strategy of Aloe vera, Curcuma longa and Ocimum sanctum extracts in functional prevention of fluoride led oxidative stress. The pregnant Wistar rats were exposed to 100 ppm fluoride in drinking water and pups born to them were supplemented with phytoextracts daily. On 21st postpartum day, the pups were sacrificed to analyse fluoride and oxidative stress markers. Fluoride exposure significantly increased its accumulation, lipid peroxidation and decreased the activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione-S-transferase and glutathione levels in discrete regions of the central nervous system (CNS) of pups indicating oxidative stress and inhibited antioxidant defense. The results implied the vulnerability of developing CNS to fluoride toxicity. On phytoextract supplementation, the oxidant devastation was suppressed by regaining antioxidant homeostasis near normal level proving efficacy and therapeutic strategy. Among the phytoextracts supplemented the Ocimum sanctum is found to be more effective.     

Effects of arbuscular mycorrhiza and phosphorus application on arsenic toxicity in sunflower (Helianthus annuus L.) and on the transformation of arsenic in the rhizosphere

Effects of arbuscular mycorrhiza (AM) and phosphorus (P) application on arsenic (As) toxicity were studied in a rhizobox system with As-contaminated soil collected from Shimane Prefecture, Japan. The treatments consisted of a combination of two levels of AM (Glomus aggregatum) inoculation (−AM and +AM) and two levels of P application (−P and +P at 30 mg P kg⁻¹). Sunflower (Helianthus annuus L.) seedlings were cultured in rhizoboxes for 6 weeks. Rates of root AM infection in +AM treatments were about 40% regardless of P application. AM inoculation as well as P application reduced As toxicity symptoms, most clearly so in the +AM−P treatment. Plant growth was highest in the +AM + P treatment. Shoot As concentrations were slightly reduced by AM inoculation but enhanced by P application. Shoot P concentration in the +AM−P treatment was similar to that of +P treatments and was higher than in −AM−P. Analyses of rhizosphere soils at the end of the cultivation period indicated that P application increased water-soluble As (WS−As) in all compartments while AM inoculation increased WS−As in the central compartment only. Both the WS−arsenite [WS−As^(III)] and the dominant form, arsenate [WS−As^(V)], showed gradients toward the root surface. Dimethylarsine (DMAA) was detected in the +AM treatments only. To our knowledge, this is the first report of the occurrence of DMAA in the mycorrhizosphere. AM inoculation increased WS−P similarly as +P treatments did and promoted acid phosphatase activity in the soil. In conclusion, AM inoculation alleviated the effects of As toxicity by improving P nutrition without increasing As concentrations in the shoots. Moreover, AM appeared to be involved in the transformation of soil inorganic As into less toxic organic forms.     

Ocimum sanctum aqueous leaf extract provides protection against mercury induced toxicity in Swiss albino mice

HgCl2 (5.0 mg/kg body weight) induced toxicity led to significant elevation of lipid peroxidation (LPO) level but decline in the glutathione content in liver of Swiss albino mice. In serum of HgCl2 treated mice there was significant elevation in serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) activities but significant decline in the alkaline phosphatase activity. Animals treated with O. sanctum extract (10 mg/kg body weight, po) before and after mercury intoxication showed a significant decrease in LPO level, SGOT and SGPT activities and increase in serum alkaline phosphatase activity and glutathione (GSH) content. Ocimum treatment alone did not alter SGOT, SGPT and alkaline phosphatase activities but significantly enhanced reduced glutathione. The results suggest that oral administration of Ocimum extract provides protection against HgCl2 induced toxicity in Swiss albino mice.     

Response of cyanobacteria to arsenic toxicity

Arsenic content of cyanobacterial biomass, soil and water samples from arsenic-contaminated area of eastern India were estimated. It was found that arsenic content in cyanobacterial biomass (276.9 μg g⁻¹) was more than soil (19.01 μg g⁻¹) or water sample (244.13 μg L⁻¹). Shallow tube well water showed more arsenic (244.13 μg L⁻¹) than deep tube well water (146.13 μg L⁻¹). Arsenic resistant genera recorded from the contaminated area were Oscillatoria princeps, Oscillatoria limosa, Anabaena sp. and Phormidium laminosum. Among these, P. laminosum was isolated and exposed to different concentration of Arsenic in vitro (0.1–100 ppm) to study the toxicity level of arsenic. Modulation in stress enzymes and stress-related compounds were studied in relation to lipid peroxidase, catalase, super oxide dismutase (SOD), ascorbate peroxidase (APX), reduced glutathione and carotenoids in arsenic exposed biomass to understand the resistance mechanism of the genus both in laboratory condition as well as in natural condition. Arsenic content of cyanobacterial biomass from contaminated area was more (276.9 μg g⁻¹) than laboratory exposed sample (37.17 μg g⁻¹), indicating bioconcentration of arsenic in long-term-exposed natural biomass. Overall, more activity of catalase was recorded in cyanobacterial biomass of natural condition whereas SOD and APX were at higher level in laboratory culture.     

Effects of 28-homobrassinolide on growth, lipid peroxidation and antioxidative enzyme activities in seedlings of Zea mays L. under salinity stress

The effects of 28-homobrassinolide (28-homoBL) on seedling growth, lipid peroxidation and antioxidative enzyme activities in the seedlings of Zea mays L. (var. Partap-1) under salt (NaCl) stress were studied. The surface-sterilized seeds were germinated in petriplates containing different concentrations of NaCl (25, 50, 75 and 100 mM) only, 28-homoBL (10⁻⁷, 10⁻⁹ and 10⁻¹¹ M) only and NaCl supplemented with 28-homoBL for 7 days. The activities of superoxide dismutase (SOD, EC 1.15.1.1), guaiacol peroxidase (POD, EC 1.11.1.7), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APOX, EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2) were analysed in 7 day-old seedlings. It was observed that 28-homoBL treatments reduced the toxicity of salt on seedling growth considerably. Lipid peroxidation level was significantly increased under saline stress, but lowered with 28-homoBL applications revealing less oxidative damage. Further 28-homoBL treatments to the seedlings showed an enhancement in activities of SOD, POD, CAT and APOX. The activities of all antioxidative enzymes were further increased in seedlings treated with solution containing 28-homoBL and salt together as compared to seedlings treated with different concentration of salt solution only.     

Improving the performance of transplanted rice by seed priming

Transplanting is the major method of rice cultivation in the world, in which seedlings are raised in nursery and then transplanted into well puddle and prepared fields. The traditional nursery sowing method is tedious and produces week seedlings that reduce the final yield due to high mortality. The potential of seed priming to improve the nursery seedlings and thus the transplanted rice was evaluated in the present study. The experiment was conducted in the rice growing area (31.45° N, 73.26° E, and 193 m) of Pakistan, during 2004–2005. Seed priming tools employed during the investigation included traditional soaking, hydropriming for 48 h, osmohardening with KCl or CaCl₂ (Ψ_s −1.25 MPa) for 24 h (one cycle), 10 ppm ascorbate for 48 h or seed hardening for 24 h. Priming improved the initial seedling vigor and resulted in improved growth, yield and quality of transplanted fine rice while traditional soaking behaved similar to that of untreated control. Osmohardening with CaCl₂ resulted in the best performance, followed by hardening, ascorbate priming and osmohardening with KCl. Osmohardening with CaCl₂ produced 3.75 t ha⁻¹ (control: 2.87 t ha⁻¹) kernel yield, 11.40 t ha⁻¹ (control: 10.03 t ha⁻¹) straw yield and 24.57% (control: 22.27%) harvest index. The improved yield was attributed due to increase in the number of fertile tillers. Significant positive correlation was found between mean emergence time of nursery seedlings and kernel yield, nursery seedling dry weight and kernel yield, fertile tillers and kernel yield, and leaf area duration and kernel yield.     

水稻依赖抗坏血酸H2O2清除系统在抗铁毒中的作用

根据营养液培养试验从水稻Ａｚｕｃｅｎａ×ＩＲ６４ 发展的一双单倍体（ＤＨ） 群体中筛选出抗铁毒与敏感品系。在铁毒害处理后,各品系的抗坏血酸过氧化物酶（ＡＰ） 、脱氢抗坏血酸还原酶（ＤＲ） 、谷胱甘肽还原酶（ＧＲ） 的活性均有明显提高;水稻受铁毒后的生物量递减量与ＡＰ、ＤＲ、ＧＲ 活性呈负相关。说明抗坏血酸过氧化物酶Ｈ２Ｏ２ 清除系统在水稻抗铁毒中起着十分重要的作用。     

光照条件下低温对水稻籼粳亚种幼苗抗氧化物质含量的影响

与对低温不敏感的粳稻台北309和武育粳相比,对低温敏感的籼稻IR64、CA212和Pusa经光照条件下8℃处理后最大光合速率(Pmax)和原初光化学效率(Fv/Fm)下降较多,出现了O2-·、过氧化氢、氧化型谷胱甘肽(GSSG)和氧化型抗坏血酸(DHA)的大量累积,其GSSG和DHA的含量分别与叶绿素含量的下降呈极显著负相关,表明光照条件下低温胁迫下,还原态的谷胱甘肽(GSH)和抗坏血酸的再生受阻,不能有效地清除活性氧,导致其叶绿素含量降低和光合能力受抑,而汕优63的变化位于上述两种类型之间。其中AsA/DHA和GSH/GSSG的变化与叶绿素含量的变化呈极显著正相关。