Downy mildew on peas (Peronospora viciae f sp pisi)

Downy mildew, Peronospora viciae, on peas is widely distributed all over the world. This fungus causes systemic infection of seedlings, local infections on leaves and pod infections. Mycelia and oospores of P viciae can be found in seed coats. However, transmission of the infection from seed to seedling has not been reported. Oospores in the soil are the most important primary inoculum. Conidia can be distributed over long distances. Treatment of seeds with acylalanine fungicides is very effective against systemic seedling infection. There is a variation in resistance to downy mildew among pea varieties. Some varieties have race-specific resistance but there are also varieties with non-race-specific partial resistance.Le mildiou du pois, Peronospora viciae f sp pisi. Le mildiou du pois, Peronospora viciae, est largement distribué sur le pois dans le monde entier. Le champignon provoque une infection systémique sur les plantules, des infections localisées sur les feuilles et des infections des gousses. Le mycelium et les oospores de P viciae peuvent être trouvés sur le tégument de la graine. Cependant la transmission de l'infection de la graine à la plantule n'a pas été signalée. Ce sont les oospores dans le sol qui constituent l'inoculum primaire le plus important. Les conidies peuvent être dispersées sur de longues distances. Le traitement des semences avec des fongicides à base d'acylaniline est très efficace contre les infections systémiques des plantules. Il existe une variabilité de la résistance entre les variétés de pois. Certaines variétés ont une résistance spécifique à certaines races, mais il y a aussi des variétés possédant une résistance non-spécifique

Optimization of extraction methods for determination of the raffinose family oligosaccharides in leguminous vine peas (Pisum sativum L.) and effects of blanching

The extraction procedure for analysis of the raffinose family oligosaccharides (RFOs) in blanched leguminous vine peas was optimized. For this purpose, 25 pea samples from different cultivars and of different maturity were chosen at random. The effect of blanching was also studied in four cultivars. The yield of oligosaccharides was almost double on average when extracted with 50% ethanol as compared with 80% ethanol. This was generally valid for all three oligosaccharides, with some exceptions for verbascose, where 80% ethanol was shown to be as effective as 50% ethanol. Extraction at room temperature and at boiling temperature gave similar yields, while 15 min of extraction gave lower yields than 30 and 60 min of extraction, which were similar. The loss of oligosaccharides following blanching was 32% on average, with verbascose showing the highest loss (56.4%), followed by raffinose (28.4%) and stachyose (16.3%). It can be concluded that the procedure used for extraction is of great importance when analysing the RFOs in immature peas, and that there is considerable loss of these sugars during blanching, which is the process commonly used to prepare the frozen commercial product. (c) 2006 Elsevier Inc. All rights reserved

Total antioxidant capacity in different pea (Pisum sativum) varieties after blanching and freezing

Thirty-five varieties of the green pea (Pisum sativum L.) were analysed for their total antioxidant capacity (TAC. After blanching and freezing, the water-soluble fraction had, on average, a TAC of 0.61(0.22) mumol/g (mean(SD)) and the water-insoluble fraction a value of 0.23(0.08) mumol/g. There was a significant correlation between the TAC in the water-soluble and water-insoluble fractions (r = 0.41; p < 0.001). The peas had been grown during two consecutive years and were harvested at two different periods during the second year, 1999. Regarding the antioxidant capacity in both the water-soluble and the water-insoluble extract, there was a significant difference between the varieties but not between the harvest periods. A significant correlation (r = 0.72) between TAC in the water-soluble fraction and ascorbic acid content was found. Ascorbic acid accounted for a large part of the water-soluble antioxidant capacity. Further studies are necessary to reveal other compounds explaining the variation in pea antioxidant capacity and the mechanisms involved. Measurement of TAC may be a convenient route for the selection of pea varieties with optimal functional and health effects. (C) 2003 Elsevier Ltd. All rights reserved

Content of low molecular weight carbohydrates in vining peas (Pisum sativum) related to harvest time, size and brine grade

Knowledge of how the content of low molecular weight carbohydrates (LMWC), including the raffinose family oligosaccharides (RFO; raffinose, stachyose and verbascose), changes in unripe peas (Pisum sativum) around harvest time, is today limited. An early and a late maturing cultivar of peas were harvested with 24 h of each other on seven different occasions, of which three were chosen for this study. The pea samples were divided into three groups by size and brine grading, and then analysed with regard to the content of low molecular weight carbohydrates. The content of raffinose and stachyose increased in all groups during a period of 5 days. Peas that sank (sinkers) in the brine grading test had a higher content of raffinose and stachyose and a lower content of sucrose than floating peas, indicating that sinkers have reached a greater degree of maturation. The content of verbascose remained the same or decreased during the study period. In conclusion, the date of harvesting green peas for freezing affects the contents of RFO

First report of "Candidatus Liberibacter solanacearum" associated with psyllid-affected carrots in Sweden

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