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1.
Magnetic field effects on different plant species have been subject of many studies in the last decade. Magnetic fields are known to induce changes in plant metabolism, growth and productivity. In this study, effect of magnetic field on date palm weight and water content has been investigated. Seedlings of date palm were treated with two types of magnetic fields in two separate experiments. In the first experiment, seedlings were treated with static magnetic field SMF using electromagnetic circuit set to produce three levels of magnetic field intensities 10, 50 and 100 mT for different durations (0, 30, 60, 120, 180 and 240 min). In the second experiment seedlings were treated with alternating magnetic field AMF, using magnetic resonance imaging providing 1500 mT for 0, 1, 5, 10 and 15 min. After two months of exposure, plants growth parameters (fresh, dry weights and water content for both leaves and roots) were recorded. The measurements revealed that leaf fresh, dry weight and water content increased significantly in response to SMF treatment. Similarly, roots fresh weight and water content were increased significantly; however roots dry weight increasing were insignificant. In the second experiment, AMF has affected plant growth all parameters were increased significantly. Measurements reached the highest level at 15 min of exposure. This study revealed that magnetic fields affect date palm growth parameters by increasing osmotic pressure and water potential which increase water absorption and enhance flesh weight.  相似文献   

2.
Leafhopper Cicadulina bipunctata is represented the main insect as a pathogen for phytoplasma disease occurring by insect-transmitted plant viruses in date palm orchards. Therefore, it is important to investigate the potential effect of some insecticides against such insect. The adults of leafhopper C. bipunctata were collected from date palm orchards in Alhasa, Eastern province, Saudi Arabia. Three insecticides from different classes--beta-cyfluthrin (pyrethroids), imidacloprid (neonicotinoids) and abamectin (natural compounds)--have been evaluated in vivo against adults C. bipunctata. This stage was exposed to residual film of various concentrations of each insecticide on transparent plastic cups using a Potter precision laboratory spray tower. Bioassay test showed that both beta-cyfluthrin and imidacloprid caused 100% mortality by 500 ppm at 24 h after treatment, whereas abamectin gave the same mortality by 50 ppm at the same time. Toxicity values revealed that abameetin was the most potent insecticide compared with beta-cyfluthrin and imidacloprid, where the lethal concentrations LC50 and LC95 were 24.58 ppm and 116.73 ppm at 3 h after treatment, respectively. Therefore, abamectin can be a possible candidate to be applied on date palm or ground grass by the Ministry of Agriculture after successful field experiments.  相似文献   

3.
Collapsing gully erosion is a specific form of soil erosion types in the hilly granitic region of tropical and subtropical South China, and can result in extremely rapid water and soil loss. Knowledge of the soil physical and chemical properties of farmland influenced by collapsing gully erosion is important in understanding the development of soil quality. This study was conducted at the Wuli Watershed of the Tongcheng County, south of Hubei Province, China. The aim is to investigate soil physical and chemical properties of three soil layers(0–20, 20–40 and 40–60 cm) for two farmland types(paddy field and upland field) in three regions influenced by collapsing gully erosion. The three regions are described as follows: strongly influenced region(SIR), weakly influenced region(WIR) and non-influenced region(NIR). The results show that collapsing gully erosion significantly increased the soil gravel and sand content in paddy and upland fields, especially the surface soil in the SIR and WIR. In the 0–20 cm layer of the paddy field, the highest gravel content(250.94 g kg~(–1)) was in the SIR and the lowest(78.67 g kg~(–1)) was in the NIR, but in the upland filed, the surface soil(0–20 cm) of the SIR and the 40–60 cm soil layer for the NIR had the highest(177.13 g kg~(–1)) and the lowest(59.96 g kg~(–1)) values of gravel content, respectively. The distribution of gravel and sand decreased with depth in the three influenced regions, but silt and clay showed the inverse change. In the paddy field, the average of sand content decreased from 58.6(in the SIR) to 49.0%(in the NIR), but the silt content was in a reverse order, increasing from 27.9 to 36.9%, and the average of the clay content of three regions showed no significant variation(P0.05). But in the upland filed, the sand, silt and clay fluctuated in the NIR and the WIR. Soils in the paddy and upland field were highly acidic(p H5.2) in the SIR and WIR; moreover lower nutrient contents(soil organic matter(SOM), total N and available N, P, K) existed in the SIR. In the 0–20 cm soil layer of the paddy field, compared with the NIR and the WIR, collapsing gully erosion caused a very sharp decrease in the SOM and total N of the SIR(5.23 and 0.56 g kg~(–1), respectively). But in the surface soil(0–20 cm) of the upland field, the highest SOM, total N, available N, available P and available K occurred in the NIR, and the lowest ones were in the SIR. Compared with the NIR, the cationexchange capacity(CEC) in the SIR and WIR was found to be relatively lower. These results suggest that collapsing gully erosion seriously affect the soil physical and chemical properties of farmland, lead to coarse particles accumulation in the field and decrease p H and nutrient levels.  相似文献   

4.
The virulent strain B6 of Curvularia lunata was screened out from 65 fungus strains isolated from the diseased leaves of barnyardgrass (Echinochloa crus-galli). Greenhouse and field studies were conducted to evaluate the feasibility of the strain being exploited as a mycoherbicide for barnyardgrass control in paddy fields. The results of pathogenicity experiments showed that this strain was highly pathogenic to barnyardgrass at the 1- to 2.5-leaf stages. The fresh weight reduction increased with the increase of inoculated conidial concentrations and the prolongation of dew duration. Strain B6 provided excellent barnyardgrass control when it was applied at the concentration of 1×104-1×106 conidia mL-1 in paddy fields with water layer. This strain was very safe to rice and the most plant species except wheat, barley and corn. Findings of this study indicated that this strain could be a potential mycoherbicide for barnyardgrass control in paddy fields in the future.  相似文献   

5.
A field experiment was carded out to study genotypic difference in the effect of waterlogging on photosynthesis, chlorophyll content and antioxidative enzyme activities in barley. Waterlogging caused a rapid decline in net photosynthetic rate (Pn) and stomatal conductance (gs), and little change in chlorophyll content during early days of the treatment. A dramatic increase in malondialdehyde (MDA) content, superoxide dismutase (SOD) and peroxidase (POD) in waterlogged plants in the early days of the experiment was found, indicating the occurrence of oxidative stress in barley plants exposed to waterlogging. There was a highly significant difference in the changed extent of all these parameters among genotypes.Franklin and Yongjiahong Liuleng Damai, which were relatively sensitive to waterlogging in terms of growth, photosynthesis and chlorophyll content, accumulated much more MDA than the other two relatively tolerant genotypes (93-3143 and QS).After removal of waterlogging, the genotypic difference became much greater in recovering of these examined parameters.Yongjiahong Liuleng Damai showed higher recovery, while Franklin only recovered to 50% of the control at the 14 day after waterlogging removal. It may be concluded that it is the difference in anti-oxidative stress caused by waterlogging that account for the major difference in photosynthesis among barley genotypes.  相似文献   

6.
The influence of twelve different pesticides(six insecticides and six fungicides) on lipase production by Isaria fumosorosea was investigated under laboratory conditions. Imidacloprid caused higher reduction in enzyme activities at all three concentrations whereas very low reduction in enzyme activities was caused by azadrichtin and Indoxacarb when used at 10μg/ml. In case of fungicides, propiconazole and pyraclostrobin caused higher reduction in enzyme activities at all three concentrations whereas low reduction in enzyme activities was caused by chlorothalonil and mancozeb when used at 10 μg/ml. Different insecticides significantly affected the toxicity of I. fumosorosea lipase against second instar Dysmicoccus neobrevipesnymphs. I.fumosorosea lipase combined with azadrichtin was proved to be the most aggressive, and those from control were the least virulent with a mean ST50 value of 6.34 ± 0.41 d.  相似文献   

7.
A field experiment was conducted in 2009 and 2010 growing seasons, to study the effect of foliar application of iron-chelated "Fe-EDTA" at concentration 0, 100 and 200 mg/L on the seasonal dynamic of mineral composition of N, P, K, Fe and Zn in petioles and berries of Halwani Lebanon and Kamali grape cultivars, grown on a calcareous soil in Mosul region, Iraq. The results revealed that the foliar application of 200 mg Fe/L caused a significant increase of N, P, K, Fe and Zn concentrations in petioles and berries compared with the control for both seasons. Additionally, the N, P, K, Fe and Zn concentration in petioles were high at the beginning of the growth season, whereas, decrease towards in the end of the growth season in both cultivars and seasons. While the N, P, K, Fe and Zn in berry content was increased towards from berry set to veraison and ripening stage in both cultivars and seasons. So there are various element contents in the cultivars.  相似文献   

8.
Expression of insecticidal protein for transgenic Bacillus thuringiensis (Bt) cotton is unstable and related to nitrogen metabolism. The objective of this study was to investigate the relationship between leaf carbon nitrogen ratio (C/N) and insecticidal efficacy of two Bt cotton cultivars. C/N ratio and Bt protein content were both measured at peak square period and peak boll period respectively under 5-7 d high temperature and different nitrogen fertilizer rates on the Yangzhou University Farm and the Ludong Cotton Farm, China. All plants were grown in field. The results showed that the C/N ratio enhanced slightly and the Bt protein content remained stable at peak square period, but significant increases for the C/N ratio and decreases markedly for the leaf Bt protein concentration were detected at the peak boll period. The similar patterns at the two growth periods were found for the leaf C/N ratio and Bt protein content by different N fertilizer treatments. When nitrogen rate was from 0 to 600 kg ha-l, the C/N ratio was reduced by 0.017 and 0.006 for Sikang 1 and Sikang 3 at peak square period, compared to the 1.350 to 1.143 reduction for Sikang 1 and Sikang 3 at peak boll period, respectively. Correspondingly, the leaf Bt protein contents were bolstered by 2.6-11.8 and 26.9-36.9% at the two different growth periods, respectively. The results suggested that enhanced C/N ratio by high temperature and nitrogen application may result in the reduction of inseetiocidal efficacy in Bt cotton, especially in peak boll period.  相似文献   

9.
Reclamation of salt-affected land plays an important role in mitigating the pressure of agricultural land due to competition with industry and construction in China. Drip irrigation was found to be an effective method to reclaim salt-affected land. In order to improve the effect of reclamation and sustainability of salt-affected land production, a field experiment (with reclaimed 1-3 yr fields) was carried out to investigate changes in soil physical, chemical, and biological properties during the process of reclamation with cropping maize and drip irrigation. Results showed that soil bulk density in 0-20 cm soil layer decreased from 1.71 g·cm-3 in unreclaimed land to 1.44 g ·cm^-3 in reclaimed 3 yr fields, and saturated soil water content of 0-10 cm layer increased correspondingly from 20.3 to 30.2%. Both soil salinity and pH value in 0-40 cm soil layer dropped markedly after reclaiming 3 yr. Soil organic matter content reduced, while total nitrogen, total phosphorus, and total potassium all tended to increase after cropping and drip irrigation. The quantities of bacteria, actinomycete, and fungi in 0-40 cm soil layer all greatly increased with increase of reclaimed years, and they tended to distribute homogeneously in 0-40 cm soil profile. The urease activity and alkaline phosphatase activity in 0-40 cm soil layers were also enhanced, but the sucrase activity was not greatly changed. These results indicated that after crop cultivation and drip irrigation, soil physical environment and nutrients status were both improved. This was benefit for microorganism's activity and plant's growth.  相似文献   

10.
Soil flame disinfestation(SFD) is a form of physical disinfestation that can be used both in greenhouses and on field crops. Its use for soil disinfestation in different crop growing conditions makes it increasingly attractive for controlling soilborne pathogens and weeds. But little is known about the effect on weeds and soilbrone diseases. This study reports on greenhouses and field crops in China that determined the efficacy of SFD to control weeds, nematodes and fungi. It also determined the impact of SFD on the soil physical and chemical properties(water content, bulk density, NO_3~–-N content, NH_4~+-N content, conductivity and organic matter) in three field trials. A second generation SFD machine was used in these trials. SFD treatment significantly reduced weeds(87.8%) and root-knot nematodes(Meloidogyne incognita)(98.1%). Plant height and crop yield was significantly increased with SFD treatment. NO_3~–-N and NH_4~+-N increased after the SFD treatment, and there was also an increase in soil conductivity. Water content, bulk density and organic matter decreased significantly in the soil after the SFD treatment compared to the control. Soil flame disinfestation is a potential technique for controlling weeds and diseases in greenhouses or in fields. SFD is a non-chemical, safe, environmentally-friendly soil disinfection method.  相似文献   

11.
To assess the risks of forchlorfenuron after application, a residue analysis method for ferchlorfenuron in cucumbers and the red soil of Southern China was established, and the dissipation behavior and residue characteristics of forchlorfenuron were studied under field conditions. The field trials, including dissipation and residue experiments, were conducted in Hunan, Yunnan and Hainan Provinces. Forchlorfenuron was applied at 32 a.i.g ha-1 rate for the dissipation study and both 21 and 32 a.i.g ha-1 for the residue study. Representative cucumbers and soil samples were collected at predetermined intervals for HPLC for UV-detector analysis. The average recoveries of the method were 80.8%-92.0% with coefficients variation (CV) between 0.4% and 11.8%. The detection limit of forchlorfenuron in cucumbers and soil samples was 0.003 mg · kg-1 and the minimum detectable amount was 3.0×10-10 g. The half life of forchlorfenuron in cucumbers in the three provinces changed as: Yunnan (5.50 days), Hunan (5.88 days), and Hainan (6.53 days) and in the soil was observed: Hainan (6.54 days), Hunan (7.64 days), and Yunnan (8.39 days). The maximum terminal residue in cucumbers at 32 a.i.g ha-1 rate after 5 days was 0.009 mg · kg-1 (Yunnan) followed by 0.0085 mg · kg-1 (Hainan) and 0.0082 mg · kg-1 (Hunan) which was below MRL value of 0.01 mg · kg-1 established by the USA, EPA. So a waiting period of 5 days should be established after spaying on cucumbers to avoid hazard to human beings.  相似文献   

12.
Effect of chlorimuron-ethyl on biochemical mechanism in tolerant sugar beet was investigated to provide basic data on using the tolerant genotype properly. Tolerant sugar beet was used to analyze its biochemical mechanism under chlorimuron- ethyl stress with frame culture in field and water culture. Glutathione S-transferase (GST) activity of leaves in tolerant sugar beet was remarkably increased as chlorimuron-ethyl was preemergence applicated at 0.5 and 1.5 g a.i. hw1, at the same time glutathione (GSH) content increased 50.0-490.1 p.g g-~. GST activity of sensitive sugar beet decreased 122.6 U mg-~ min-1 compared with tolerant sugar beet and GSH content only increased to 7.4 p.g g-~ at chlorimuron-ethyl 0.5 g a.i. ha-~ in sensitive sugar beet. The higher GST activity and GSH content conjugated chlorimuron-ethyl absorbed in tolerant sugar beet and made it lost activity. Acetolactate synthases (ALS) activity of the tolerant sugar beet increased to 62.5 and 70.6%, respectively in seedling and leaf growth period, at the same time ALS activity of the sensitive variety was decreased to 36.8 and 64.8%, respectively. The rapidly increased GST activity, GSH content, and ALS, the target enzyme activity were the important pathways for enduring chlorimuron-ethyl in tolerant sugar beet.  相似文献   

13.
Laboratory and field studies were conducted on some aspects of biology and control methods of fruit stalk borer Oryctes elegans Prell., the study was conducted in date palm orchards in south Baghdad during the years 2009 and 2010. The laboratory rearing result ofO. elegans indicated that the larval stage period was very long reached 6 months, the body weight of the mature larva was 7.61 gm, the length and body circumference were 7.58 and 5.23 cm respectively. The period of pupa stage was 19 day and 2.97 gm body weight, while the length and body circumference were 3.74 and 3.21 cm respectively .While the weight of adult stage was 1.67 gm and 3.14 cm, 2.71 cm for the length and circumference body respectively. Results of hand collection larvae in palm trees during the regular annual service, showed reduction in population density of adults to 1.4 adult/trap per week compared with 3.3 and 14.0 adult/trap per week in the orchards were larvae collected partially and without hand collection by using the light traps with solar energy (Magna Traps, Russell IPM) respectively. Also, the study proved the existence of an inverse relation between the moon light and adult activity, which affected on the adult number cough in light traps. These results indicated that the hand collection of larvae works during months January, February, March and April at synchronized with the larval stage on palm trees, and use Magna Traps as an effective method to control O. elegans through IPM programs in palm orchards.  相似文献   

14.
Biological control is usually the first choice of control and prevention method for integrated pest management (IPM) strategies and has now been widely implemented by Indonesian oil palm plantations. Entomopathogenic fungus, i.e., Metarhizium anisopliae, Cordyceps militaris and Beauveria bassiana have been demonstrated to control renowned pests of oil palm. Metarhizium has been used to control Oryctes larvae and the mortality has ranged from 91.67% to 100% in laboratory and 7.4% to 88.75% in the field. Metarhizium has been applied in combination with a termite baiting system (TBS) to control termites in the field for preventive and curative action as well. In many oil palm plantations in Indonesia, Cordyceps has been used to reduce the field moth population ofSetothosea asigna. Application of Cordyceps within the oil palm circle was able to infect S. asigna pupae up to 80%. Meanwhile, Beauveria in an effervescent formulation was demonstrated to have better efficacy on Darna trima larvae. A significant finding on the biological control of basal stem rot disease (Ganoderma) was the isolation of Trichoderma sp. and Gliocladium sp.. The efficacy was conducted with promising result and techniques on the application of Triehoderma have been developed, i.e., hole-in-hole system, surgery and a mounding method. However, as the roots developed, Trichoderma was no longer able to protect the palm from Ganoderma. In spite of that, the use of Trichoderma still prolonged the life ofoil palms by up to 2-3 years. Another fungi belonging to vesicular arbuscular mychorrhiza (VAM) has been developed to control Ganoderma. The efficacy in the nursery showed promising results and the Ganoderma incidence remained low compared to the untreated control. Large scale field trials are ongoing. Challenges on the implementation of biological control in oil palm plantations are because of application and availability of biopesticides/natural enemies. Therefore, advances in research on the formulation of biological control agents are still needed.  相似文献   

15.
A systematic study was conducted to determine the effects of water stress on the activities of protective enzymes and lipid peroxidation in maize. The results showed that, under water stress, the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in leaves and roots increased sharply at prophase and metaphase growth stages, such as, male tetrad stage, but then declined towards the physiological maturity. The protective enzyme activities in roots were lower than those in leaves. The content of malondialdehyde (MDA) increased according to the severity of water stress. The content of MDA in roots was lower than that in leaves. The activities of protective enzymes and lipid peroxidation in roots were positively related to that in leaves with most of the correlation coefficients being significant. The content of soluble proteins in roots and leaves decreased with increasing drought stress. The ear characteristics deteriorated and the economic yields of maize decreased significantly under water stress. The main factors that caused reduction of yields were the decrease in the number of ear kernels and 100-kernel weight.  相似文献   

16.
The North China Plain(NCP) is one of major breadbaskets in China. Crop growth and grain yield differ significantly with spatial variations of soil properties. This study aims to identify the key soil properties in relation to the grain yield for the winter wheat(Triticum aestivum L.)-maize(Zea mays L.) cropping system in a high-productivity farmland of the NCP. The field trials were conducted in three fields with different grain yield levels in Tai’an City, Shandong Province, China, during the 2009–2012 period. Consistent field management strategies were applied in the three fields. Fifty-one physical and chemical indicators of the soil profile as related to grain yield were evaluated. An approximate maximum of 17.8% annual average grain yield difference was observed in the fields during the period of 2009–2012. The soil indicators were classified into three clusters with specific functions using cluster analysis, and three key indicators were extracted from each cluster to characterize the different soil properties of three fields. The first cluster represented soil water retention capacity, and the key indicator was available soil water(ASW), which ranged from 153 to 187 mm in the 1.2 m profile and was correlated positively with grain yield. The second cluster represented soil water conductivity, as measured by saturated hydraulic conductivity(K s). The higher yield field had a greater capacity to retain topsoil water for its lower K s(1.9 cm d–1) in the 30–70 cm soil layer as compared to the lower yield field. The third cluster represented nutrient storage and supply, as indicated by the ratio of nutrient content to silt+clay content of the top soil layer. The ratio of soil organic matter(OM), total nitrogen(TN), available P, exchangeable K+ to silt+clay content in the 0–20 cm soil layer were 19.0 g kg–1, 1.6 g kg–1, 94.7 mg kg–1, 174.3 mg kg–1 in the higher yield field, respectively, and correlated positively with the grain yield. By characterizing the differences in soil properties among fields with different yield levels, this study offers the scientific basis for increasing grain yield potential by improving the soil conditions in the NCP.  相似文献   

17.
Drought stress is often the most limiting factor to maize and sorghum production in the semi-arid areas.This study evaluates the response of electrolyte leakage,chlorophyll,carotenoid and anthocyanin contents in maize (cv.Melkassa-2 and sorghum cv.Macia) after exposure to and recovery from pre- and post-flowering dehydration in plants grown in a controlled environment growth chamber under constant environmental conditions (12/12 h day/night,28-32/17°C day/night temperature,60-80% RH and PPFD of 1 200-1 400 μmol m-2 s-1),at the Department of Botany,University of Cape Town,South Africa.It was revealed that dehydration induced increases in electrolyte leakage was observed in both species during both pre- and post-flowering stages.Electrolyte leakage was however,higher during post- than pre-flowering dehydration in both species.Dehydration during both pre- and post-flowering stages caused a decrease in chlorophyll and carotenoid contents in both maize and sorghum.Chlorophyll and carotenoid contents of both pre- and post-flowering dehydrated sorghum was markedly higher than that of maize throughout the duration of the dehydration period.As opposed to chlorophyll and carotenoid contents,anthocyanin contents increased during pre- and post-flowering dehydration in both species.Differences were however,observed between both species in the response of anthocyanin content to pre- and post-flowering dehydration.Full recovery of chlorophyll,carotenoid and anthocyanin contents were observed in those plants rehydrated during pre-flowering stages.There was however,no recovery in both species during post-flowering rehydration.This study should help understand some adaptive mechanisms developed by maize and sorghum during the dehydration and rehydration periods and contribute to identify useful traits for breeding programs.  相似文献   

18.
Drought stress is often the most limiting factor to maize and sorghum production in the semi-arid areas.This study evaluates the response of electrolyte leakage,chlorophyll,carotenoid and anthocyanin contents in maize (cv.Melkassa-2 and sorghum cv.Macia) after exposure to and recovery from pre- and post-flowering dehydration in plants grown in a controlled environment growth chamber under constant environmental conditions (12/12 h day/night,28-32/17°C day/night temperature,60-80% RH and PPFD of 1 200-1 400 μmol m-2 s-1),at the Department of Botany,University of Cape Town,South Africa.It was revealed that dehydration induced increases in electrolyte leakage was observed in both species during both pre- and post-flowering stages.Electrolyte leakage was however,higher during post- than pre-flowering dehydration in both species.Dehydration during both pre- and post-flowering stages caused a decrease in chlorophyll and carotenoid contents in both maize and sorghum.Chlorophyll and carotenoid contents of both pre- and post-flowering dehydrated sorghum was markedly higher than that of maize throughout the duration of the dehydration period.As opposed to chlorophyll and carotenoid contents,anthocyanin contents increased during pre- and post-flowering dehydration in both species.Differences were however,observed between both species in the response of anthocyanin content to pre- and post-flowering dehydration.Full recovery of chlorophyll,carotenoid and anthocyanin contents were observed in those plants rehydrated during pre-flowering stages.There was however,no recovery in both species during post-flowering rehydration.This study should help understand some adaptive mechanisms developed by maize and sorghum during the dehydration and rehydration periods and contribute to identify useful traits for breeding programs.  相似文献   

19.
[Objective] The study aimed to explore the effects of magnetic treatment on the quality of chicken semen stored at low temperature. [Method] 5 ml fresh chicken semen was divided into five groups equally, each of which was diluted at the volume ratio 1∶4. With the group without magnetic treatment as the control, the other four groups were magnetized for 6, 12, 24 and 48 min in the self-made magnetizer, respectively. Subsequently, all the five groups were stored at 2-4 ℃, and the sperm motility, survival time, survival index and deformity rate were observed regularly. [Result] Comparing with the control group, the magnetic groups showed higher sperm motilities and effective survival indices as well as lower deformity rates. The effective survival index of the group magnetized for 24 min was the highest and increased by 7.75% in contrast to the control. [Conclusion] Magnetic treatment can effectively enhance the quality of chicken semen stored at low temperature.  相似文献   

20.
The gene expression patterns of antioxidative enzymes in cucumber (Cucumis sativus L.) fruits at four different maturity stages, immature (3-8 d after anthesis (DAA), mature (9-16 DAA), breaker (17-22 DAA), and yellow (35-40 DAA), were determined before and after cold storage at 2°C for 9 d and after subsequent rewarming at 20°C for 2 d. The electrolyte leakage and malondialdehyde content in cucumber fruits were increased after cold storage and subsequent rewarming. Increased expressions of peroxidase, ascorbate peroxidase (APX), and monodehydroascorbate reductase after cold storage played an important role in cucumber fruits to cope with chilling injury. The elevated cyt-superoxide dismutase, catalase, APX and dehydroascorbate reductase after subsequent rewarming in cucumber fruits facilitated the recovery from chilling stress. The highest expression levels of all the seven antioxidative enzyme genes in yellow fruits might be responsible for the enhanced chilling tolerance. Cucumber fruits at earlier developmental stages was more susceptible to chilling stress than those at later stages. The relative higher gene expressions of antioxidative enzymes genes at earlier developmental stages may be the responses to the sever oxidative stress caused by chilling injury.  相似文献   

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