冷锻炼处理减轻低温贮藏桃果实冷害的能量代谢机理

为探讨通过维持低温贮藏桃果实能量代谢水平而减轻冷害的有效方法,以‘大久保’桃为试材,分别以24、5、0℃贮藏为对照,研究冷锻炼处理(8℃冷锻炼5d后转入0℃冷藏,CAT)对维持冷藏及其货架期间桃果实线粒体呼吸代谢相关酶及三磷酸腺苷(ATP)含量的影响。结果表明:24℃贮藏模式下桃果实的H+-ATPase、Ca2+-ATPase、琥珀酸脱氢酶(SDH)和细胞色素氧化酶(CCO)活性在贮藏过程中2～3d出现了活性高峰,之后随着果实的软化衰老而显著下降。5℃贮藏桃果实贮藏期间的H+-ATPase、Ca2+-ATPase、SDH、CCO活性和ATP含量最低,且下降速度也最快;0℃贮藏次之,而CAT贮藏可有效抑制桃果实H+-ATPase、SDH和CCO活性的下降,保持较高的ATP含量。随着贮藏时间的延长,货架期期间H+-ATPase、Ca2+-ATPase、SDH、CCO活性和ATP含量均降低,但CAT处理明显高于5、0℃冷藏处理。这表明冷锻炼处理可通过调节线粒体呼吸代谢酶活性,维持果实较高的能量水平,有利于减轻果实冷害的发生并延长贮藏期。     

毛霉诱导脐橙产抗病物质对指状青霉和酸腐菌的抑制

绿霉和酸腐是柑橘果实采后主要的病害,生产上迫切需要化学杀菌剂的替代方法。该研究对毛霉诱导脐橙果皮产生的具有抗病活性的红色物质(Citru Peel Red-substance Extract,CPRE)进行部分分离纯化,评价了CPRE对指状青霉和酸腐菌的抑菌活性,分析活性成分对两病原真菌菌丝细胞壁与膜功能的影响。结果表明,在50～200μg/mL的质量浓度下,CPRE对指状青霉和酸腐菌的孢子萌发,芽管伸长,菌丝生长有强烈的抑制作用,并且呈现剂量效应,最低抑菌浓度均为200μg/mL。进一步研究表明,与空白对照比较,50、100μg/mL抗菌活性成分处理明显改变指状青霉和酸腐菌菌丝细胞壁中几丁质分布,降低了细胞壁中几丁质含量、促进了质外体碱性磷酸酶的释放,表明CPRE严重损伤两致病真菌菌丝的细胞壁功能;CPRE处理还明显损伤两病菌菌丝的细胞膜通透性(P0.05),刺激菌丝膜外电导率显著上升(P0.05),加剧细胞内蛋白和核酸的丢失,降低了菌丝细胞膜总脂质含量,影响了细胞膜的正常功能。上述结果表明,红色抗菌成分在防控柑橘采后绿霉病和酸腐病中有潜在应用前景。     

茶树油熏蒸处理对草莓果实采后病害和品质的影响

为了研究茶树油对草莓防腐保鲜的作用效果,对人工接种灰葡萄孢霉（Botrytis cinerea）和根霉（Rhizopus stolonifer）的草莓果实进行不同浓度、不同时间的茶树油熏蒸处理,测定20℃贮藏下的病害发生情况,并运用体外实验研究该熏蒸处理对病原菌孢子萌发和菌丝生长的影响。同时,还分析了接受该处理的果实在贮藏期间的品质变化趋势。研究发现：茶树油熏蒸处理可降低草莓果实灰霉病和根霉病的发病率和病斑直径,抑制其孢子萌发和菌丝生长,减缓草莓果实在贮藏期间的品质下降。结果表明茶树油熏蒸用于草莓保鲜是可行的,浓度为2000 mg/L熏蒸3 h即可有效延长草莓货架期2-3 d。     

茶树油熏蒸处理对香蕉采后炭疽病害的影响

为了探讨植物提取物对香蕉采后病害的防治效果,以香蕉果实为材料,采用菌丝生长速率方法测定不同剂量（0～40 μL）的茶树油（TTO）及其主要成分（4-松油烯醇、α-松油醇、γ-松油烯和1,8-桉叶油素）对香蕉炭疽病菌的离体抗菌活性,并用TTO及其主要成分熏蒸处理接种炭疽病菌的香蕉果实,测定果实常温贮藏（25°C,相对湿度75%）的发病情况和TTO处理对接种果实防御酶活性的影响。结果表明,TTO、4-松油烯醇和α-松油醇均能显著抑制离体炭疽病菌的菌丝生长,质量浓度越高,抑制效果越明显;1.25 g/L TTO处理降低了接种炭疽病菌果实的发病程度,0.32 g/L 4-松油烯醇和α-松油醇处理对接种果实病斑直径的抑制效果显著好于TTO。另外,1.25 g/L TTO处理提高了接种果实过氧化物酶（POD）和苯丙氨酸解氨酶（PAL）的酶活性,抑制了多酚氧化酶（PPO）酶活性。初步研究表明TTO熏蒸处理在控制香蕉果实采后腐烂和提高果实抗病性上具有应用可行性,4-松油烯醇和α-松油醇可能是其主要活性成分。     

费菜黄酮对柑橘意大利青霉菌抑制作用的研究

为研究费菜黄酮对意大利青霉的抑菌效果并揭示其抑菌机制,本试验采用损伤接种法接种意大利青霉至柑橘,观察0、0.3、0.6、1.2 mg·mL^-1费菜黄酮对柑橘青霉病的控制效果,探究其对意大利青霉细胞膜通透性、细胞成分释放、菌丝表面结构、菌丝丙二醛(MDA)和过氧化氢(H₂O₂)含量等指标的影响。结果表明,费菜黄酮能够显著抑制菌丝生长,1.75 mg·mL^-1浓度下的抑制率为75.82%,7.00 mg·mL^-1 浓度下的抑制率达到100%。经费菜黄酮处理后,意大利青霉细胞膜通透性显著增加,糖类等胞内物质释放至细胞外;扫描电镜显示菌丝体结构遭到破坏,菌丝体表面出现褶皱、塌陷;同时引起H₂O₂和MDA含量增加;柑橘果实的发病率和病斑直径减小。本研究结果为天然杀菌剂的研制以及抑菌机制的后续研究提供了一定的理论依据。     

茶树油熏蒸对草莓采后病害和品质的影响

为了研究茶树油对草莓保鲜的作用效果,对人工接种灰葡萄孢霉（Botrytis cinerea）和根霉（Rhizopus stolonifer）的草莓果实进行不同质量浓度、不同时间的茶树油熏蒸处理,测定20℃贮藏下的病害发生情况,并运用体外试验研究该熏蒸处理对病原菌孢子萌发和菌丝生长的影响。同时,还分析了接受该处理的果实在贮藏期间的品质变化趋势。研究发现：茶树油熏蒸处理可降低草莓果实灰霉病和根霉病的发病率和病斑直径,抑制其孢子萌发和菌丝生长,减缓草莓果实在贮藏期间失重率的上升,维持较高的硬度、可溶性固形物和可滴定酸含量。结果表明茶树油熏蒸用于草莓保鲜是可行的,质量浓度为2?000 mg/L,熏蒸3 h可明显延长草莓货架期。     

开口箭提取物对采后香蕉抗炭疽病菌活性的研究

为探讨植物提取物对香蕉采后病害的防治，采用孢子萌发法和菌丝生长速率测定百合科植物开口箭的甲醇提取物及其乙酸乙酯分部萃取物和正丁醇分部萃取物对香蕉炭疽病菌的离体抗菌活性，选用正丁醇分部萃取物进行耐高温(121℃处理20 min)、紫外光照射(30 W紫外灯距50 cm直射15 h)和酸处理(调节pH 3)的抗菌稳定性研究，并进行了提取物处理香蕉的贮藏防病试验。结果表明，开口箭甲醇提取物及其乙酸乙酯分部萃取物和正丁醇分部萃取物抑制香蕉炭疽病菌孢子萌发的半效应浓度(EC₅₀)分别为1490.27，638.40，1112.65 μg/mL，抑制香蕉炭疽病菌菌丝生长的EC₅₀分别为1262.16，451.02，955.58 μg/mL，正丁醇分部萃取物的抗菌活性不受热、紫外线和酸等因子的影响，用开口箭提取物处理采后香蕉果实，具有明显降低其潜伏性炭疽病发病率的作用。     

高压电场处理对贮藏番茄活性氧代谢的调节

为探讨高压电场调控采后果实成熟衰老的作用机理,研究了交变电场和稳恒电场处理对采后番茄活性氧代谢的影响。试验结果表明：交变电场处理可诱导贮藏前期番茄超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性,延缓贮藏后期SOD活性上升和CAT活性下降;稳恒电场处理对酶活性的诱导不显著。两种电场处理均延缓了过氧化物酶（POD）活性高峰出现的时间。稳恒电场处理果实整个贮藏过程中保持了高水平的抗坏血酸（AsA）以及还原型谷胱甘肽（GSH）含量。整个贮藏期间高压电场处理均显著抑制了番茄过氧化氢含量以及超氧阴离子的产生。     

外源NO对镉胁迫下长春花质膜过氧化ATP酶活性及光合特性的影响

为了解镉胁迫下外源NO对地被植物生理响应的调控机制,采用盆栽试验研究了外源NO（SNP）对镉胁迫下长春花幼苗生长、活性氧代谢、质膜ATP酶活性及光合特性的影响。结果表明,外施100μmol·L^-1SNP能缓解25mg·kg一镉胁迫对长春花幼苗生长的抑制,增加叶长、叶宽、株高、基径和生物量。与镉胁迫相比,施用SNP能够降低叶片和根系中丙二醛（MDA）、过氧化氢（H2O2）含量和过氧根离子自由基（O2^-·）产生速率,提高过氧化氢酶（CAT）、过氧化物酶（POD）、超氧化物歧化酶（SOD）活性及还原型谷胱甘肽（GSH）含量。SNP能显著缓解镉胁迫对叶绿素a（Chla）、叶绿素b（Chlb）和总叶绿素的抑制,提高叶片净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）和气孔限制值（Ls）,降低胞间CO2浓度（G）和瞬时光能利用效率（LUE）。同时,外源NO能诱导叶片和根系中质膜H＋-ATPase和Ca2＋-ATPase活性提升到正常水平（对照）。但外施100μmol·L-1 NO分解产物NaNOx或SNP相似物Na3Fe（CN）6对镉胁迫则无明显缓解作用。因此,外源NO可通过提高活性氧清除能力,增加叶绿素含量,增强质膜ATP酶活性,从而提高叶肉细胞光合能力,加强离子跨膜运输和信号转导,缓解镉胁迫对细胞质膜的损伤。     

钙对苹果果实钙调蛋白含量和Ca2+ -ATPase活性及其基因表达的影响

研究不同浓度钙（0、1和10 mmo1/L CaCl2 ;5 mmo1/L EGTA）对苹果果实钙调蛋白（CaM）含量和Ca2+-ATPase活性及其基因表达的影响。利用同源克隆方法分离CaM和Ca2+-ATPase基因,采用荧光定量PCR方法研究它们表达特征。结果表明,果实切片外源补钙,可溶性Ca2+及CaM含量在高钙处理12 h达到高峰;高钙处理12 h质膜Ca2+-ATPase活性显著增加,与胞内CaM含量增加时间一致;高钙处理24 h液泡膜Ca2+-ATPase活性显著增加;随着质膜和液泡膜Ca2+-ATPase活性显著增加,可溶性Ca2+含量在加钙处理48 h显著下降。研究基因表达发现,加钙处理6 h苹果CaM基因的表达量显著增加;加钙处理12 h苹果Ca2+-ATPase基因的表达量显著增加,与CaM含量及质膜Ca2 +-ATPase活性变化一致。果实缺钙处理显著增加CaM基因表达量,而苹果Ca2 +-ATPase基因的表达量没有显著变化。上述研究表明,苹果补钙可以提高细胞内可溶性Ca2+和CaM含量以及CaM基因的表达量,有效启动钙信使系统;质膜及液泡膜Ca2+-ATPase是调控胞内Ca2+关键的酶,通过提高质膜及液泡膜Ca2+-ATPase的活性及Ca2+-ATPase基因的表达量,维持胞内Ca2+的稳态水平。     

Antifungal activity of strawberry fruit volatile compounds against Colletotrichum acutatum

Eight volatile products characterizing strawberry aroma, which is generated from the oxidative degradation of linoleic and linolenic acids by a lipoxygenase (LOX) pathway, were examined because of their antifungal activity against Colletotrichum acutatum, one of the causal agents of strawberry anthracnose. In this study, the effects of aldehydes, alcohols, and esters on mycelial growth and conidia development were evaluated. (E)-Hex-2-enal was found to be the best inhibitor of mycelial growth [MID (minimum inhibitory doses)=33.65 microL L(-1)] and of spore germination (MID=6.76 microL L(-1)), while hexyl acetate was the least effective of all volatile compounds tested (MID=6441.89 microL L(-1) for mycelial growth and MID=1351.35 microL L(-1) for spore germination). Furthermore, the antifungal activity of (E)-hex-2-enal on susceptibility of strawberry fruits to C. acutatum was also confirmed. The presence of these molecules in jars containing strawberry fruits inoculated with a suspension of spores inhibited the fungus growth and prevented the appearance of symptoms. Moreover, a study of the effects of (E)-hex-2-enal on conidial cells of C. acutatum was evaluated by transmission electron microscopy. This volatile compound altered the structures of the cell wall and plasma membrane, causing disorganization and lysis of organelles and, eventually, cell death.     

Residue levels and effectiveness of pyrimethanil vs imazalil when using heated postharvest dip treatments for control of Penicillium decay on citrus fruit

The influence of fungicide concentration and treatment temperature on residue levels of pyrimethanil (PYR) in comparison with the commonly used fungicide imazalil (IMZ) was investigated in orange fruits following postharvest dip treatments. The dissipation rate of PYR residues was recorded as a function of storage conditions. The fungicide efficacy against green and blue molds caused by Penicillium digitatum and Penicillium italicum, respectively, was evaluated on different citrus varieties following the fungicide application at 20 or 50 degrees C. Residue levels of PYR in Salustiana oranges were significantly correlated with the fungicide dosage, but residue concentrations were notably higher (ca. 13-19-fold) after treatment at 50 degrees C as compared to treatments at 20 degrees C. After treatment at temperatures ranging from 20 to 60 degrees C, PYR and IMZ residues in Salustiana oranges were significantly correlated with dip temperatures. Dissipation rates of PYR during storage were negligible in both Salustiana and Tarocco oranges. Results obtained on wounded, noninoculated Miho satsumas revealed that when treatments were performed at 50 degrees C, PYR or IMZ concentrations needed to achieve the complete control of decay were 8- and 16-fold less than by treatment at 20 degrees C. When fruits were inoculated with either P. digitatum or P. italicum, the application of 400 mg L(-1) PYR at 20 degrees C or 100 mg L(-1) PYR at 50 degrees C similarly reduced green and blue mold development. These results were corroborated by storage trials on Marsh grapefruits and Tarocco oranges. The lowest concentration of PYR required to achieve almost total protection of the fruit against decay accounted for 100 mg L(-1) at 50 degrees C and 400 mg L(-1) at 20 degrees C, respectively. Treatments did not affect fruit external appearance, flavor, and taste. It is concluded that postharvest PYR treatment represents an effective option to control green and blue mold in citrus fruit and that integration of fungicide applications and hot water dips may reduce the possibility of selecting fungicide-resistant populations of the pathogen, as a consequence of increased effectiveness of the treatment.     

丁香精油对甜樱桃采后优势致腐真菌的控制及其抑菌机理

为探明植物精油对甜樱桃采后优势致病菌的抑菌效力及抑菌机理,以山东泰安地区主栽品种红灯为试验材料,从自然腐烂的甜樱桃果实上分离纯化优势致病菌,采用形态学方法并结合ITS序列法进行鉴定,选用丁香精油从体外熏蒸和接触2种作用方式研究其对主要病原真菌的抑菌效果。结果表明,甜樱桃采后的3种主要致腐真菌分别为灰葡萄孢菌(Botrytis cinerea)、链格孢菌(Alternaria alternata)和胶孢炭疽菌(Colletotrichum gloeosporioides);体外抑菌试验表明,一定浓度的丁香精油能显著抑制3种致病菌的菌丝生长和孢子萌发,熏蒸处理较接触效果更好,对B. cinerea、 A. alternata和C. gloeosporioides的最小抑菌浓度(MIC)分别为120、100和100 μL·L^-1;试验还表明丁香精油破坏了菌丝形态,其抑菌机理可能与精油疏水性造成的微生物膜系统结构破坏、及胞内主要内容物流失有关。综上所述,丁香精油作为甜樱桃贮藏前的熏蒸剂具有较好的应用潜力。     

Low temperature metabolism of apple phenolics and quiescence of Phlyctaena vagabunda.

The content of chlorogenic acid, (+)-catechin, (-)-epicatechin, phloretin glycosides, and quercetin glycosides in fresh and stored Golden Delicious apples (Malus domestica Borkh) was determined. The relative amount of phenolics in the peel, with the exception of chlorogenic acid and (-)-epicatechin, was higher than that in the flesh. In addition, quercetin glycosides were detected only in the skin. These compounds were tested for fungicidal activity against Phlyctaena vagabunda Desm., the causal agent of a postharvest rot. Chlorogenic acid only inhibited P. vagabunda spore germination and mycelial growth in vitro. Changes of apple phenolics and polyphenol oxidase activity during cold storage and the biological activity of these phenolics have also been analyzed with reference to the development of quiescent infections during cold storage plus shelf life at room temperature. The results obtained suggested that phloridzin and chlorogenic acid in combination with polyphenol oxidase activity could function to arrest P. vagabunda in quiescent infections associated with immature and ripening apple fruit.     

Inhibition of citrus postharvest pathogens by vapor of citral and related compounds in culture

The vapors of citral, its isomers geranial and neral, and its related compounds were examined for their effect on Penicillium digitatum, Penicillium italicum, and Geotrichum candidum, the major fungi responsible for postharvest spoilage of citrus. Vapor of citral and its two isomers generated from 15 microL L(-1) aqueous solutions in Petri dishes inhibited development of the three pathogens, with concentrations of 2-6 microL L(-1) also being effective against P. italicum. Vapors of citral and geranial from 15 microL L(-1) solutions were fungicidal to P. digitatum and G. candidum, while neral was fungicidal to G. candidum. Citral-related compounds were much less effective, with effectiveness decreasing from citronellal to citronellol and citronellic acid. R and S isomers of these three citral-related compounds generally had similar effects on the fungi tested.     

Protein changes in the albedo of citrus fruits on postharvesting storage

In this work, major protein changes in the albedo of the fruit peel of Murcott tangor (tangerine x sweet orange) during postharvest ageing were studied through 2D PAGE. Protein content in matured on-tree fruits and in fruits stored in nonstressing [99% relative humidity (RH) and 25 degrees C], cold (99% RH and 4 degrees C), and drought (60% RH and 25 degrees C) conditions was initially determined. Protein identification through MS/MS determinations revealed in all samples analyzed the occurrence of manganese superoxide dismutase (Mn SOD), actin, ATP synthase beta subunit (ATPase), citrus salt-stress associated protein (CitSap), ascorbate peroxidase (APX), translationally controlled tumor protein (TCTP), and a cysteine proteinase (CP) of the papain family. The latter protein was identified in two different gel spots, with different molecular mass, suggesting the simultaneous presence of the proteinase precursor and its active form. While Mn SOD, actin, ATPase, and CitSap were unchanged in the assayed conditions, TCTP and APX were downregulated during the postharvest ageing process. Ageing-induced APX repression was also reversed by drought. CP contents in albedo, which were similar in on- and off-tree fruits, were strongly dependent upon cold storage. The active/total CP protein ratio significantly increased after cold exposure. This proteomic survey indicates that major changes in protein content in the albedo of the peel of postharvest stored citrus fruits are apparently related to the activation of programmed cell death (PCD).     

磷、钾营养对柑桔果实产量、品质和贮藏性的影响

采用田间试验以柑为材料研究了连续4年施用磷、钾肥后对柑桔果实的产量、品质和贮藏性的影响。结果表明,施用磷、钾肥,尤其磷、钾肥配施可显著提高柑桔果实的单果重和产量,以及采收时果实的可溶性固形物含量、可溶性糖含量、还原糖含量、糖/酸比和维生素C(Vc)含量,降低可滴定酸含量;并且可以有效地降低柑桔果实在贮藏过程中的失重率和烂果率,减缓糖分、酸度和Vc含量的下降。磷钾营养对于提高柑桔果实的耐贮性和维持贮藏过程中果实的风味和营养品质有一定的作用。     

川芎提取液对脐橙的防腐保鲜效果

为了开发植物源脐橙贮藏保鲜技术,该文研究了川芎提取液在离体和活体条件下对采后脐橙的主要致腐菌意大利青霉和指状青霉的抑制作用,以及对贮藏期脐橙品质和生理生化的影响。结果显示:在离体条件下,川芎提取液对2种供试菌种有显著的抑制作用(P0.05),最低抑菌质量浓度均为25.00 mg/m L;在活体条件下,川芎提取液能有效抑制2种病原菌在脐橙上的生长,且质量分数为4%效果较好,与体积分数为50%乙醇处理的对照相比,差异显著(P0.05);在脐橙采后贮藏中,川芎提取液对脐橙的防腐保鲜效果与其质量分数相关,其中质量分数为4%的效果较好,与蒸馏水处理的对照相比,能够显著(P0.05)降低采后脐橙的腐烂率、失重率和丙二醛含量,延缓总酸的下降,以及诱导过氧化物酶活性上升,有利于维持可溶性固形物和总糖质量分数,而对维生素C和果皮色泽的变化无显著影响(P0.05)。结果表明,川芎提取液用于脐橙贮藏保鲜切实可行,研究结果为脐橙天然保鲜剂的开发及脐橙在贮藏、运输和销售期间防腐保鲜提供参考。     

基于周长面积分形维数的柑橘品种机器识别

柑橘品种自动识别是有针对性的柑橘病虫害防治、肥培管理、采摘等自动化作业的重要环节。为了评价宫川温州蜜柑、脐橙朋娜和沪溪无核椪柑3个柑橘品种机器自动识别的可行性,采集3个柑橘品种花萼面和侧面数字图像,以图像中柑橘轮廓像素数和区域像素数作为柑橘周长与面积,通过周长—面积方法计算其分形维数。将周长、面积和分形维数作为品种特征值,用小波神经网络识别3个品种,正确识别率分别为95%、95%、97.5%。试验结果表明,用周长、面积和分形维数3个特征值能有效识别3个柑橘品种,并具有较高的识别精度。     

宽皮柑橘对辊式剥皮机的设计与试验

为改善目前宽皮柑橘加工业中以手工去皮为主的现状,提高柑橘剥皮效率,该文根据宽皮柑橘果皮包着宽松,易与果肉分离等特点,设计了一种可以实现快速去皮的宽皮柑橘对辊式剥皮机。柑橘进入设备后,在刮板的带动下翻转向前运动,运动过程中不同形式且相向转动的剥皮辊夹持并撕扯翻起的果皮,从而将果皮从柑橘上整体剥离。该样机主要由机架、传动装置、对辊装置、拨动装置和下料装置等部件组成,具有结构紧凑,果皮分离能力强等特点。试验结果表明:样机可以很好地完成剥皮功能,宽皮柑橘果皮去净率高于97.5%,果肉损伤率低于2.68%,生产率达到202.5 kg/h,基本满足生产需求。该研究可为中国柑橘加工业中自动去皮设备研制和发展提供参考。