Zimmermann U.,University of Wurzburg |
Ruger S.,University of Wurzburg |
Shapira O.,Migal Galilee Technological Center |
Shapira O.,Hebrew University of Jerusalem |
And 11 more authors.
Turgor pressure provides a sensitive indicator for irrigation scheduling. Leaf turgor pressure of Musa acuminate was measured by using the so-called leaf patch clamp pressure probe, i.e. by application of an external, magnetically generated and constantly retained clamp pressure to a leaf patch and determination of the attenuated output pressure Pp that is highly correlated with the turgor pressure. Real-time recording of Pp values was made using wireless telemetric transmitters, which send the data to a receiver base station where data are logged and transferred to a GPRS modem linked to an Internet server. Probes functioned over several months under field and laboratory conditions without damage to the leaf patch. Measurements showed that the magnetic-based probe could monitor very sensitively changes in turgor pressure induced by changes in microclimate (temperature, relative humidity, irradiation and wind) and irrigation. Irrigation effects could clearly be distinguished from environmental effects. Interestingly, oscillations in stomatal aperture, which occurred frequently below turgor pressures of 100 kPa towards noon at high transpiration or at high wind speed, were reflected in the Pp values. The period of pressure oscillations was comparable with the period of oscillations in transpiration and photosynthesis. Multiple probe readings on individual leaves and/or on several leaves over the entire height of the plants further emphasised the great impact of this non-invasive turgor pressure sensor system for elucidating the dynamics of short- and long-distance water transport in higher plants. © 2009 German Botanical Society and The Royal Botanical Society of the Netherlands. Source
Matityahu I.,Migal Galilee Technological Center |
Glazer I.,Migal Galilee Technological Center |
Holland D.,Newe Yaar Research Center |
Bar-Ya'akov I.,Newe Yaar Research Center |
And 3 more authors.
Food and Bioprocess Technology
The demand to extend the marketing period of pomegranates requires a better understanding of the processes occurring during postharvest storage. Among the important factors that limit the long-term storage of pomegranates are disorders occurring on the fruit husk: fungal decay, chilling injury, shrinkage due to weight loss, and husk scald, all leading to loss of visual quality. The aim of this study was to examine processes that taking place during storage, and to analyze the relationship between the total antioxidant capacity and total phenolics content of the husks and the development of husk disorders in seven accessions. While the level of total phenolics increased during storage, concomitantly with the color index, the level of punicalagin, the main polyphenol in the husks with the highest antioxidant activity, declined during storage. The content of titratable acidity was also reduced. Regression analysis indicates that fruit having a high antioxidant capacity, high total phenolics content, and high levels of punicalin in their husks have a better ability to resist fungal decay and weight loss, in addition to being less sensitive to husk scald. On the other hand, the results suggest that the development of most husk disorders is not correlated to the content of total soluble solids, titratable acidity, punicalagin, anthocyanin, or husk color. Nonetheless, poorly colored accessions were relatively more sensitive to chilling injury expressed as surface pitting, compared with the more colored accessions. The appearance of these chilling injury symptoms was not correlated to total phenolics or the antioxidant capacity. © 2013 Springer Science+Business Media New York. Source
Glazer I.,Migal Galilee Technological Center |
Glazer I.,Hebrew University of Jerusalem |
Masaphy S.,Migal Galilee Technological Center |
Masaphy S.,Tel-Hai Academic College |
And 8 more authors.
Journal of Agricultural and Food Chemistry
Aqueous extracts of pomegranate peels were assayed in vitro for their antifungal activity against six rot fungi that cause fruit and vegetable decay during storage. The growth rates of Alternaria alternata, Stemphylium botryosum, and Fusarium spp. were significantly inhibited by the extracts. The growth rates were negatively correlated with the levels of total polyphenolic compounds in the extract and particularly with punicalagins, the major ellagitannins in pomegranate peels. Ellagitannins were also found to be the main compounds in the bioactive fractions using bioautograms, and punicalagins were identified as the main bioactive compounds using chromatographic separation. These results suggest that ellagitannins, and more specifically punicalagins, which are the dominant compounds in pomegranate peels, may be used as a control agent of storage diseases and to reduce the use of synthetic fungicides. © 2012 American Chemical Society. Source