番荔枝果实采后生理与保鲜技术研究进展

番荔枝果实采后难以贮藏保鲜的特性制约着我国番荔枝产业的进一步发展。对国内外关于番荔枝果实采后呼吸强度及乙烯产量、相关酶类、果实软化、果实褐变等生理变化、采后病理及保鲜技术的研究进展作了综述。     

水果采后生物防治拮抗机理的研究进展

近20年来,人们在水果采后生物防治领域里取得了显著的成绩。目前巳经分离获得了数百种对水果采后主要病害有明显拮抗效果的生物拮抗菌。很多拮抗菌经过生产中试,有的巳制成了生物药剂用于水果采后的商业化处理。有关拮抗菌的抑病机理研究也一直贯穿于采后生物防治的整个发展历程。本文在探讨了水果采后拮抗菌剂病机理的基础上,回顾了该领域的研究进展,并从拮抗菌与病原菌发生拮抗作用的4条主要途径入手,对该领域的研究成果及研究方法作一简要总结。     

果蔬采后病害的生物防治(综述)

采用生物防治措施控制采后病害是当前果蔬采后保鲜的重要研究方向。概述了生物防治果蔬采后病害的方法,包括利用拮抗菌、诱导抗病性、天然植物产物以及抗病基因工程技术在果蔬病害防治上的研究与应用。     

控制果蔬采后病害的生物学技术

化学农药对环境和农产品的污染直接影响人类的健康,已成为当今公众所关注的主要问题之一。为了保证农产品的卫生和安全,世界各国都在探索能代替化学农药的防病新技术。生物防治是近年来被证明很有成效的新途径,它主要是利用微生物之间的拮抗作用,选择对农产品不造成危害的微生物来抑制引起采后腐烂的病原真菌的生长。生物防治的研究主要包括主要包括以下三方面：（１）选用有拮抗作用的微生物;（２）利用植物和动物产生的自然抗     

水杨酸处理对采后园艺产品的作用

本文结合作者自己的研究结果 ,综述了水杨酸对园艺产品的采后作用 (包括延长切花保鲜期、减轻果实腐烂、推迟洋葱等产品的发芽和对果蔬产品贮藏期间品质、呼吸速率、乙烯释放、抗逆、活性氧代谢方面影响 )的研究进展 ,并对这些结果进行了分析 ;对高浓度外源SA处理引起的负面作用以及存在的一些问题进行了探讨     

1株用于甜瓜采后病害生物防治的假单胞菌株的分离及鉴定

甜瓜以营养丰富口味独特而深受世人青睐。同时,其采后病害高效、"绿色"防治药剂的缺乏也成为多年来困扰甜瓜生产的难题。本文采用直接生物测定的方法,从健康的甜瓜表面分离到1株有生防潜能的菌株X4。该菌株对引起甜瓜主要采后病害的粉红单端胞菌(Trichothecium roseum)、镰刀菌(Fusarium spp.)和链格孢菌(Alternaria alternata)的防治效果分别达到了90.6%、84.4%和67.4%;定殖实验显示,接菌4 d后该菌在瓜内数量可上升并稳定至1.1×10~6CFU/ml;通过16S rDNA测定、形态特征观察及生理生化测定结果表明该菌为Pseudomonas fluorescens biovarⅢ。     

Shoot regeneration in response to carbon source on internodal explants of Annona muricata L.

Adventitious shoot regeneration from internodal explants of mature plants of Annona muricata L. was obtained on Nitsch media. Meristems were induced with sorbitol as the sole carbon source supplemented with 2 mg l^–1 of benzylaminopurine and 0.5 mg l^–1 naphthaleneacetic acid. Adventitious shoots were developed only when the explants were transferred onto growth regulator-free media containing sucrose, galactose, or glucose. A hypothesis is proposed for the involvement of sorbitol in the induction and development of de novo shoots from internodal explants of mature trees of A. muricata.     

In vitro and in vivo bio-assay of phytobiocidal effect of plant extracts on Alternaria solani causing agent of early blight disease in tomato

The efficacy of six locally available plants extract was evaluated for their phytobiocidal effect on Alternaria solani the causal agent of early blight (EB) disease of tomato and was compared with commercial fungicide mancozeb under in vitro and in vivo conditions. Under in vitro conditions, Eucalyptus globus and Datura alba were found to be ineffective, while the remaining plants extract (Allium sativum, Curcuma longa, Melia azedarach, Zingiber officinale) significantly reduced A. solani growth on PDA. Increasing concentrations of A. sativum (0–25%) were found negatively correlated with growth of A. solani on PDA. Among the tested plants, A. sativum extract at 20% concentration was found most effective against A. solani witnessed by both in vitro and in vivo experiments result. It reduced EB disease up to 75.11% over positive control. Similarly, among the different plants extract, maximum plant height (76.25 cm), fruit size (57.50 cm³) and yield (511.30 g) were observed in A. sativum sprayed treatments (20%), beside mancozeb and negative control. Upon phytochemical analysis of these extracts, flavonoids, alkaloids, saponins, tannins, terpenoids, glycosides and steroids were detected. Present study showed that 20% concentration of garlic extract has the potential to reduce EB disease severity, while having no noticeable phytotoxicity.     

The effect of early blight disease caused by Alternaria solani on shoot growth of young tomato plants

The effect of increasing spore concentration of Alternaria solani (Early blight disease) on the shoot growth of young tomato plants was analysed. Changes in growth were related to the severity of infection which increased with increasing inoculum. Leaf production was not affected but dry weights and especially leaf expansion were decreased. The effective leaf areas of the five inoculated leaves (L1-L5 numbered from the plant base) were drastically decreased by expanding necrotic lesions and, to a lesser extent, by premature leaf fall. Healthy leaves expanding soon after inoculation (L6, L7) were markedly affected by the disease on the lower leaves and had decreased specific leaf areas (ratio of leaf area to leaf dry weight) but later formed (from L8) leaves were less affected and had greater specific leaf areas than equivalent leaves on uninoculated plants.     

Alternaria mycotoxins in black rot lesion of tomato fruit: Conditions and regulation of their production

Alternaria represents the most common decay organism of the post-harvest tomato fruit. The prevalent type of decay, black rot lesion, is caused byA. alternata which may invade tomato tissue damaged by sun scald.Aspergillus niger, A. flavus andRhizopus stolonifer come in the second count level and occupy high to moderate occurrence. The mainly natural mycotoxins produced in rotted tomato are alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TA). Altertoxin I & II (AT-I & AT-II), in addition to AOH, AME and TA were produced by localA. alternata in a synthetic medium. The optimum temperature for toxin production byA. alternata IMI 89344 was 28 °C for AOH and AME, 21 °C for TA, and 14 °C for AT-I and AT-II. The growth and toxin were produced in a noticeable amount at 7 °C but drop at 35 °C. Significant inhibition in these toxins was attained at 500 ppm cinnamon oil in YES-Czapeks medium and in a tomato homogenate.     

Metabolite profiling and quantification of phenolic compounds in methanol extracts of tomato fruit

The consumption of tomatoes and tomato products has been associated with a reduction in the risk of contracting some types of cancer and other chronic diseases. These beneficial properties may be attributed to the presence of key metabolites and the interactions among them. We have developed and validated an analytical method for the comprehensive profiling of semi-polar metabolites in the methanol extract of three cultivars of raw tomatoes (Daniela, Raf and Rambo) grown in Almería, in south-east Spain. Diode-array and time-of-flight/ion-trap mass spectrometry detectors were used to ensure the wide detection of metabolites with highly divergent properties. The masses thus detected were assigned by matching their accurate mass-signals with tomato compounds reported in the literature, and supplemented by UV and MS/MS information, reference compounds and existing metabolite databases. In this way we were able to identify tentatively 135 compounds belonging to various structural classes, 21 of which are to our knowledge reported for the first time in the tomato fruit. Among the metabolites identified, the most abundant were phenolic compounds. This class of secondary metabolites is attracting considerable attention from producers and consumers due to their antioxidant activity and nutritional properties. Their quantitative analysis was achieved by using closely related derivatives for each family.     

Postharvest biocontrol of Alternaria alternata in Chinese winter jujube by Rhodosporidium paludigenum

Aims:  This study was conducted to measure the efficacy of the marine antagonist Rhodosporidium paludigenum in the suppression of postharvest decay of Chinese winter jujube caused by Alternaria alternata and to explore the possible mode of action involved.
Methods and Results:  The efficacy of controlling postharvest diseases by R. paludigenum was examined. Rapid yeast colonization of wounds was observed during the first 48 h at 25°C. The yeast at 1 × 10⁸ cells ml⁻¹ of washed cells suspension provided better control of A. alternata than any other treatment. The concentration of the antagonist had significant effects on biocontrol effectiveness: as the concentration of R. paludigenum was increased, the disease incidence decreased. Meanwhile, R. paludigenum significantly inhibited the natural development of decay and did not damage fruit quality parameters including lightness values, hue angle, firmness, soluble solids, ascorbic acid and titratable acidity in 21 days' storage at 25°C.
Conclusions:  Rhodosporidium paludigenum was effective in controlling postharvest decay of Chinese winter jujube and did not impair fruit quality parameters.
Significance and Impact of the Study:  Rhodosporidium paludigenum can be used as a nonchemical agent in postharvest biological control of Chinese winter jujube.     

钙对中华猕猴桃果实采后乙烯释放和呼吸的影响

不同浓度(0.2 mol/L、0.5 mol/L 0.8 mol/L) CaCl₂溶液真空渗透处理对中华猕猴桃果实采后乙烯释放都有明显的抑制作用,其中0.5 mol/L Ca²⁺处理尤为显著,采后5天果实仍保持极低水平的内源乙烯,乙烯峰也延迟2~4天出现。不同品种间没有明显差异。试验结果还表明,Ca²⁺处理对果实采后呼吸不存在明显的抑制作用,但不同品种间有一定差异。     

Antifungal activity of plants extracts against Alternaria solani,the causal agent of early blight of tomato

Aqueous extracts of 39 plants selected from local flora were evaluated for antifungal potential against Alternaria solani, causing early blight of tomato, at 4% concentration in Potato Dextrose Agar by poison food technique. Out of these, 13 plant extracts significantly reduced the mycelial growth of the pathogen, according to ANOVA, Tukey’s post-test. Inhibition rate of above 20% was shown by seven plant extracts namely Crotalaria trichotoma (36.6%), Citrus aurantifolia (27.3%), Azadirachta indica (23.7%), Polyalthia longifolia (23.3%), Datura metel (21.3%), Muntingia calabura (20.09%) and Oxalis latifolia (20.09%). At 2% concentration, six extracts showed significant growth inhibition namely, C. trichotoma (16.6%), A. indica (10%), Capsicum annum (7.1%), D. metel (6.6%), P. longifolia (6.3%) and C. aurantifolia (5.5%). The plant extracts shortlisted for pathogen inhibition have potential to be developed as potent fungicides in organic farming.     

Non-destructive assessment of flesh firmness and dietary antioxidants of greenhouse-grown tomato (Solanum lycopersicum L.) at different fruit maturity stages

Non-destructive methods have been widely recognized for evaluating fruit quality traits of many horticultural crops and food processing industry. Destructive (analytical) test, and non-destructive evaluation of the quality traits were investigated and compared for ‘Red Rose’ tomato (Solanum lycopersicum L.) fruit grown under protected environment. Fresh tomato fruit at five distinctive maturity stages namely; breaker (BK), turning (TG), pink (PK), light-red (LR), and red (RD) were labeled and scanned using the handheld near infra-red (NIR) enhanced spectrometer at a wavelength range of 285–1200 nm. The labeled tomato samples were then measured analytically for flesh firmness, lycopene, β-carotene, total phenolic content (TPC) and total flavonoids content (TFC). The results revealed that quality traits could be estimated using NIR spectroscopy with a relatively high coefficient of determination (R²): 0.834 for total phenolic content, 0.864 for lycopene, 0.790 for total flavonoid content, 0.708 for β-carotene; and 0.679 for flesh firmness. The accumulation of Lyco and β-Car rapidly increased in tomatoes harvested between the TG and the LR maturity stages. Harvesting tomatoes at BK maturity stage resulted in significantly higher flesh firmness than harvesting at the later maturity stages. Tomato fruits had the lowest TPC and TFC contents at the earliest maturity stage (BK), while they had intermediate TPC and TFC levels at LR and RD maturity stages. NIR spectroscopic measurements of fruit firmness and lipophilic antioxidants in tomato fruit at various maturity stages were partially in accordance with those estimated by destructive (analytical) methods. Based on these findings, we recommend using non-destructive NIR spectroscopy as an effective tool for predicting tomato fruit quality during harvest stage and postharvest processing.     

Purification,characterization of mosquito larvicidal lectin from Annona muricata and its eco-toxic effect on non-target organism

The present study investigates the purification and characterization of mosquito larvicidal lectin from the seed kernel extract of Annona muricata and toxic effects on non-target organism Chironomus costatus. Soursop lectin was purified by anion-exchange column chromatography using DEAE-cellulose with approximately molecular mass of 260 kDa and with seven distinct subunits (16, 18, 21, 22, 24, 73 and 95 kDa). Soursop lectin highest Hemagglutination (HA) titer value of 128 was recorded against hen indicator RBC type with the influence of different divalent cations such as Ca²⁺, Ba²⁺ and Mn²⁺. The lectin mediated HA activity was highly inhibited by monosaccharides of glucose and mannose and disaccharides such as trehalose and melibiose. It was found to be EDTA sensitive (at 30 mM), pH-dependent (between 6–9) and heat-labile (upto 60 °C). A significant homology for soursop lectin was recorded to leguminous seed lectin from Psophocarpus scandens in MALDI-TOF-MS analysis with 66 % of sequence coverage. Finally, the toxicity bioassay of soursop lectin resulted in 100 % larval mortality for A. aegypti at 48 h whereas only 10 % mortality recorded to non-target organism C. costatus. Therefore, we concluded that soursop lectin could be a potent insecticidal agent in integrated pest management for controlling various insect pests.     

紫外诱变改良柑橘采后病害拮抗菌柠檬形克勒克酵母研究

以柠檬形克勒克酵母(Kloeckera apiculata)为出发菌株,采用紫外线(UV)、UV LiCl等方法对其进行诱变改良.确定了处理的最佳剂量:紫外处理15 W 30 cm照射20 s,UV LiCl处理UV照射20 s并在平板中加入LiCl 0.3%(W/V).选育到一株生理特性有明显改善的变异菌株UV20-13,果实试验中,7 d后柑橘青、绿霉病的发病率分别比出发菌株降低25.56%和10.00%.生长动态测定和传代试验表明,该菌株生长特性优于出发菌株,连续传代10代,该菌株没有出现退化、回复突变等,在遗传上是稳定的.     

紫外诱变改良柑橘采后病害拮抗菌柠檬形克勒克酵母研究

以柠檬形克勒克酵母(Kloeckera apiculata)为出发菌株, 采用紫外线(UV)、UV+LiCl等方法对其进行诱变改良。确定了处理的最佳剂量：紫外处理15 W 30 cm照射20 s, UV+LiCl处理UV照射20 s并在平板中加入LiCl 0.3% (W/V)。选育到一株生理特性有明显改善的变异菌株UV20-13, 果实试验中, 7 d后柑橘青、绿霉病的发病率分别比出发菌株降低25.56%和10.00%。生长动态测定和传代试验表明, 该菌株生长特性优于出发菌株, 连续传代10代, 该菌株没有出现退化、回复突变等, 在遗传上是稳定的。