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1.
Post-infection changes in ascorbic acid, sugars, proteins and phenols were studied in guava fruits infected by major post-harvest pathogens which in order of importance wereColletotrichum gloeosporioides, (Penz.),Botryodiplodia theobromae, Pat.,Rhizopus arrhizus Fischer.,Phomopsis psidii Nag Raj and Ponnappa apud Ponnappa and Nag Raj, andPestalotiopsis versicolor (Speg.) Steyaert. Contents of ascorbic acid, sugars and proteins declined in the fruits infected byBotryodiplodia theobromae, Colletotrichum gloeosporioides, Pestalotiopsis versicolor, Phomopsis psidii andRhizopus arrhizus. Total phenols increased in fruits infected byPestalotiopsis versicolor andRhizopus arrhizus while reverse was observed in fruits infected by other pathogens.Part of the Ph.D. thesis submitted by the senior author to the Rajasthan Agricultural University, Bikaner.  相似文献   

2.
The study was performed at a vegetable farm from 2006 to 2008 in the intensive horticultural area of Lednice (South Moravia, Czech Republic), where a stolbur (phytoplasma) epidemic had occurred. The study showed that the incidence of stolbur disease reached 15% in both tomato (Lycopersicon esculentum) and pepper (Capsicum annuum), and up to 6.7% in celeriac (Apium graveolens). There were significant yield losses in the stolbur-affected plants; total yield losses were up to 60% in tomato, 93% in pepper, and 100% in celeriac. The mean yield was significantly decreased in stolbur-affected plants, compared to healthy plants (i.e. from 42.79 to 17.21 fruits per plant in tomatoes; from 10.11 to 0.74 fruits per plant in peppers). In the locality studied, it was mainly the weed plants Convolvulus arvensis and Cirsium arvense (which were frequently interspersed among the crops), which tested positive for the stolbur phytoplasma and might have provided a reservoir for the phytoplasma infection.  相似文献   

3.
Summary The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive. Potato tubers were exposed to 55°C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of eyes colonised byP. pustulans, Helminthosporium solani, andR. solani was reduced to virtually zero and the effect persisted on tubers subsequently stored at 4°C and at 15°C for up to 16 wk. Results withColletotrichum coccodes were inconclusive. Treatment suppressedPenicillium spp. which, however, rapidly recolonised the eyes during storage, leading to higher contamination levels in the treated than in the untreated tubers. With tubers inoculated withPhoma foveata, good control was achieved when the incubation period before treatment was 10 d but not when the period was 42 d.  相似文献   

4.
Tomato fruits Var Romer VFN, inoculated withFusarium equiseti, F. chlamydosporium, Geotrichum candidum, Acremonium recifei, Aspergilus flavus andA. niger showed decline in ascorbic acid content with days of incubation when compared with control (uninoculated) fruits. The total soluble sugars of the inoculated fruits also showed a reduction trend as the storage period was prolonged, but slight increase was observed on the 6th day after inoculation.  相似文献   

5.
Summary Samples of a sandy soil and a marine clay soil sterilized by steam were put in 55-1 containers insulated with polystyrene and placed outdoors on a brick pavement. Sandy soil was infested singly or in all possible combinations with root-knot nematodes (Meloidogyne spp.) and the fungiRhizoctonia solani andVerticillium dahliae, and the marine clay soil was infested with the root-lesion nematodePratylenchus neglectus and the same fungi to evaluate the effects of these organisms on the yield of potato. The experiments were carried out from 1983 to 1986. Tuber yield was reduced by single infestations of theMeloidogyne spp. andV. dahliae but not significantly byR. solani orP. neglectus. A three-factor interaction: nematode ×R. solani × V. dahliae was found in both experiments.R. solani andV. dahliae showed significant synergistic effects when soil was infested with theMeloidogyne spp. orP. neglectus.  相似文献   

6.
Summary The effect ofStreptomyces spp. (netted scab) on the growth of potato was investigated in three pot experiments, in two of which the effect ofVerticillium dahliae was also assessed. The netted scab organisms attacked all underground plant parts of susceptible potato cultivars early in the growing season; the roots were especially seriously attacked, markedly reducing tuber yield and number but prolonging the duration of the growing season. The nematicide oxamyl had little effect on the incidence of netted scab. Repeated growing of the susceptible cv. Bintje greatly increased soil contamination with the netted scab pathogens. V. dahliae reduced haulm growth before wilt symptoms were evident and it reduced tuber yield but not number. Oxamyl delayed infection byV. dahliae by controlling parasiticPratylenchus nematodes (mainlyP. thornei).  相似文献   

7.
The fruits of some wild plants were examined for their contents of mineral elements and ascorbic acid.High levels of ascorbic acid were found in fruits ofSclerocarya birrea (403.3 mg/100 g) andAdansonia digitata (337 mg/100 g). In nine of the fruits examined, the mineral contents (Ca, P) were comparable with average values found in common fruits. The iron contents were however 2–5 times higher than the values for common fruits.  相似文献   

8.
The seeds of lesser-known species —Cucumeropsis mannii, Lagenaria sicceraria varities 1 and 2 andTelfairia occidentalis, ofCucurbitaceae family were studied. The protein content ofC. mannii was 36.1% and the varieties 1 and 2 ofL. sicceraria had 32.1% and 33.3% respectively.Telfairia occidentalis had protein content of 33.2%. The fat contents ofC. mannii, L. Sicceraria var. 1 and 2 andT. occidentalis were 44.4%, 44.6%, 46.9% and 42.3% respectively. The crude fibre content for each of the two varieties ofL. sicceraria was 3.6% andT. occidentalis had 5.5%.Cucumeropsis mannii had the lowest (2.4%) fibre content. The carbohydrate contents forL. Sicceraria var. 2,C. mannii, andT. occidentalis were 12.6%, 13.2% and 14.4% respectively.Lagenaria sicceraria var. 1 had the highest value of carbohydrate (15.8%). The species were relatively rich in potassium and magnesium with range of values of 0.56% to 0.68% and 434 ppm to 444 ppm respectively.Cucumeropsis mannii andLagenaria sicceraria var. 2 had relatively high contents of calcium (117 ppm) and iron (109 ppm) respectively. The kernels of these species exhibited lipase activity.Telfairia occidentalis showed the highest degree of lipase activity.  相似文献   

9.
Summary The reaction of 40 potato clones and six accessions ofSolanum spp. to wilt caused byVerticillium dahliae and to the acetone precipitate (AP) of the toxin produced by the pathogen in vitro was studied. There was a highly significant correlation between the wilt reaction of the clones in the glasshouse, the incidence and progress of wilt and severe wilt in the field, and the degree of colonization of stem apices byV. dahliae. Of the clones and accessions evaluated, NDA8694-3, Norgold Russet, BelRus, Superior, Russet Norkotah, Norland andS. demissum were the most susceptible, while A66107-51, A68113-4, Targhee, NDA843-3, Alpha, A7805-8, A7816-14, Russet Nugget,S. chacoense, S. sparsipilum, andS. tarijense were the most resistant to wilt. The reaction of genotypes to the AP ofV. dahliae toxin in an excised leaf bioassay was not correlated with their reaction to Verticillium wilt in the field or glasshouse. Idaho Agricultural Experiment Station Article No. 89741.  相似文献   

10.
A study was conducted from October 1987 to November 1988 to accumulate data on the distribution of plant-parasitic nematodes, to examine rotation schemes and time of sampling in relation to nematode populations, and to assess the occurrence ofVerticillium spp.-Pratylenchus spp. in potato growing areas of the state of Maine.Pratylenchus penetrans andP. crenatus were encountered most frequently, with detection being 19% higher in early season (May–June) than late season (September–November). All rotation schemes supportedPratylenchus spp.Meloidogyne hapla was encountered in 14% of the early samples and 19% of the late samples. Oats-potato, potato-potato, and clover-potato supported the highestM. hapla population levels. Other nematodes detected in fewer samples and in lower numbers than the two above genera wereParatylenchus spp.,Criconemella spp.,Helicotylenchus spp. andTylenchorhynchus sp. Two plants from each of 27 fields were examined for nematode-fungus associations. Samples from 7 fields were positive forV. dahliae andP. penetrans only,V. alboatrum andP. penetrans were found in 1 field,V. alboatrum alone was detected in 1 field andP. penetrans,V. dahliae andV. alboatrum were found together in 2 fields. The detection of these nematode-fungus associations suggests that the potato early dying complex defined elsewhere in the United States may be occurring in Maine.  相似文献   

11.
Summary Two species of wild potato,S. brevidens andS. fernandezianum, were surveyed for six potato-infecting viruses in their natural habitats in the Puerto Montt Region and Robinson Crusoe Island of Chile, respectively. Potato viruses S (PVS), M (PVM) and X (PVX) and potato yellowing virus (PYV) were found in some clones of the Chilean Potato Germplasm Collection, whereas only one population ofS. brevidens out of six was virus-infected, namely by PVS. The cultivated potatoes on Robinson Crusoe Island were infected by PVS, PVM and PVX and infested byAulacorthum solani andMyzus persicae, whereasS. fernandezianum was infected by PYV and infested byA. circumflexum, A. solani andAphis spp.  相似文献   

12.
K. Scholte 《Potato Research》1990,33(2):181-190
Summary A crop rotation experiment was carried out on a light sandy soil in 1979–1986 to study the effects of the frequency of potato cropping on yield, quality and on the occurrence of soil-borne pathogens other than potato cyst nematodes. Tuber yield decreased markedly with increasing cropping frequency, but also depended on what crops were grown in rotation with potato. Growth during the early part of the season, as well as the length of the growing period, were reduced in short rotations. The fungiVerticillium dahliae andRhizoctonia solani, and root-knot nematodes (Meloidogyne spp.) were the most important yield reducing pathogens. The effects of rotation depended on the cultivar used. The percentage of mis-shapen tubers increased with increasing cropping frequency and after application of granular nematicides, but the incidence of common scab (Streptomyces scabies) was not affected.  相似文献   

13.
Summary The incidence of infection withSpongospora subterranea was studied in the non tuber-bearingSolanum brevidens andS. etuberosum and the tuber-bearingS. acaule, S. sucrense andS. tuberosum cvs Olympia and Pito. Shoot cuttings were grown in soil naturally infested withS. subterranea, or the roots were inoculated with a zoospore suspension. Logit models were used to analyse the data. The incidence ofS. subterranea was higher in plants inoculated with zoospore suspension than in those grown in infested soil (odds ratio (OR) 10.65). Ageing the inoculum reduced the incidence of infection in the plants (OR 0.30) without altering the interspecific differences. The ORs of infection (compared to cv. Olympia) were 0.07, 0.29, 0.60 and 2.88 forS. acaule, S. sucrense, S. brevidens andS. etuberosum. OnlyS. acaule was significantly more resistant to infection than cv. Olympia. No infection was detected in cv. Pito.  相似文献   

14.
The aim of the present study was to determine the integrated effect of plant extracts and hot water treatment on postharvest anthracnose and banana fruit quality. Artificially inoculated banana fruit were dipped in 10% and 20% (w/v) extracts of four plant species, viz. Acacia albida, Argemone mexicana, Dovalis abyssinica and Prosopis juliflora at room temperature (20 °C), 45 °C and 50 °C. Fruit treated separately with 20% extracts of A. albida and P. juliflora at 50 °C had reduced anthracnose incidence and severity. These treatment combinations also had the highest percentage of marketable ripe banana fruits. In conclusion, applying aqueous plant extracts at 50 °C enhanced the antifungal activity of extracts without affecting the physico-chemical properties of banana.  相似文献   

15.
青稞全蚀病和根腐病生防毛壳菌的筛选及鉴定   总被引：2，自引：0，他引：2  
青稞根腐病与青稞全蚀病是西藏青稞的常见根部病害,为筛选适合于防治青稞全蚀病与根腐病的毛壳菌,通过皿内拮抗试验、发酵粗提物抑菌试验和温室盆栽防效试验对4株毛壳菌的抑菌活性进行了鉴定,通过形态学和分子生物学方法对高活性菌株进行了鉴定。结果发现,在皿内拮抗试验中,毛壳菌41-4在培养第7天至第9天时,对青稞根腐病和全蚀病的抑制率分别达到60.00%和44.44%,抑菌带宽度均达到1.4cm。培养7d时毛壳菌41-4发酵粗提物对青稞根腐病和全蚀病的抑制率分别达到64.44%和60.00%,抑菌带宽度均达到1.5cm。在温室盆栽防效试验中,毛壳菌41-4对青稞根腐病和全蚀病的发病严重度和病情指数均有降低作用,防效分别达到62.67%和39.45%。结合形态学特征和核糖体基因内转录间隔区(rDNAITS)序列构建系统发育树,将菌株41-4鉴定为球毛壳菌Chaetomium globosum。该生防菌株可用于开发微生物菌肥,对西藏的无公害农业生产和保护西藏的原生态具有重要意义。  相似文献   

16.
Brown rot (Monilinia spp.) affects the shelf life, fruit quality and marketability of peaches (Prunus persica L.). Increasing consumer concern regarding food safety makes it necessary to search for natural environmentally friendly alternative products for postharvest disease control. In this investigation, polyethylene terephthalate (PET) punnets containing thyme oil (TO sachets) and sealed with chitosan/boehmite nanocomposite lidding films significantly reduced the incidence and severity of brown rot caused by Monilinia laxa in artificially inoculated peach fruits (cv. Kakawa) held at 25 °C for 5 days. Furthermore, PET punnets containing TO sachets and sealed with chitosan/boehmite nanocomposite lidding films significantly reduced the brown rot incidence to 10% in naturally infected fruits stored at 0.5 °C, 90% RH for 7 days and at the simulated market shelf conditions for 3 days at 15 °C, 75% RH. The chitosan/boehmite nanocomposite lidding films maintained the active components of thyme oil, thymol (56.43% RA), caryophyllen (9.47% RA) and β-linalool (37.6% RA) within the (head space volatiles) punnet. Panellists preferred fruits packed from commercial punnet containing thyme oil (sachets) and sealed with chitosan/boehmite nanocomposite lidding films due to overall appearance, taste, and natural peach flavour.  相似文献   

17.
A sample of 10000 ha of grassland in seven upland districts originally surveyed in 1970–72 was re-surveyed in 1986. Forty percent of the area was above 240 m elevation, 38% had gradients above 81/2°, 29% had poor or bad drainage and 54% was classified as having difficult or severe limitations to management. Twelve percent had been reseeded within the previous 5 years and 39% within 20 years; 6% was classified as arable grassland (in rotation with crops). Thirty-four percent was usually mown, two-thirds of it for silage. In most years 72% of grassland received fertilizer N (average application 123 kg N ha−1) and 35% received organic manure; nearly 20% received neither. Older swards tended to receive lower rates of fertilizer N than reseeds, hay fields and grazed fields less than silage fields, and fields on beef/sheep farms less than those on dairy farms. The proportion of sown species in swards averaged 35%, of which Lolium perenne accounted for 23%. A good contribution of Trifolium repens was recorded in 15% of the grassland. Herb species were recorded in 30% of the grassland, mostly in situations with low fertilizer N under hay or grazing. Agrostis spp., Poa spp., Holcus lanatus and Festuca rubra were the main unsown grasses. The average contribution of L. perenne had increased since 1970–72; it was also present in two-thirds of the area from which it was absent in 1970–72, whilst the contribution of T. repens had decreased. The incidence of Cirsium arvense and Ranunculus spp. had also decreased, whilst that of Pteridium aquilinum had increased.  相似文献   

18.
Dietary fiber and bioactive compounds are widely used as functional ingredients in processed foods. The market in this field is competitive and the development of new types of quality ingredients for the food industry is on the rise. Opuntia ficus-indica (cactus pear) produces edible tender stems (cladodes) and fruits with a high nutritional value in terms of minerals, protein, dietary fiber and phytochemicals; however, around 20% of fresh weight of cladodes and 45% of fresh weight of fruits are by-products. The objective of this study was therefore to determine the nutritional value of by-products obtained from cladodes and fruits from two varieties of Opuntia ficus-indica, examining their dietary fiber and natural antioxidant compound contents in order to obtain quality ingredients for functional foods and increase the added value of these by-products.  相似文献   

19.
Summary Accessions of tuber-bearingSolanum spp. related toS. tuberosum subsp.tuberosum were obtained from the German-Dutch collection (Braunschweig, Germany) and the Inter-regional potato collection (Sturgeon Bay, USA). They were screened for resistance toG. rostochiensis Rol andG. pallida Pa2/3. Among 1567 clones from 52 accessions, 135 clones (23 accessions) were resistant toG. rostochiensis. They mainly representedS. andigena, gourlayi, spegazzinii andvernei. Among 1689 clones (74 accessions), 105 clones (32 accessions) were resistant toG. pallida. They representedS. gourlayi, spegazzinii, sparsipilum andvernei. About 25 clones were resistant to both species.  相似文献   

20.
Summary TwoPythium spp. were isolated from diseased tubers exhibiting rots at harvest, in summer stores and also in refrigerated storage. Symptoms shared features described for both pink rot caused byPhytophthora erythroseptica and leak caused byPythium spp. The causal agents were identified asPythium aphanidermatum andP. ultimum by morphological and physiological observations and by fingerprinting using oomycete specific primers to amplify the internal transcribed spacer (ITS1) within ribosomal DNAs. The optimum temperatures for infection were 30°C forP. aphanidermatum and 25°C forP. ultimum, corresponding to the optimum temperatures for growth in vitro. The optimum concentration for infection of tubers inoculated by dipping in a suspension of oospores or hyphal swellings after wounding was found to be 103 reproductive organs/ml, whereas the infection threshold was 10 reproductive organs/ml.  相似文献   

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