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• 17

  Dec
  Winter collapse of pepper 2007/8

  Plant Protection, Vegetables

  by Shimon Pivonia, Ph.D.

  תאריך עדכון 14/1/2009

  תיאור מלא The phenomenon of winter collapse of pepper (Capsicum annuum L.), the wilting of mature plants from December through February, has been known in the Arava for many years. Over the years, the use of methyl bromide as a soil fumigant kept the phenomenon at negligible levels. Winter collapse of pepper appeared on a wider scale during the 2004/5 and 2006/7 growing seasons. The phenomenon is seen primarily in the cooler areas of the Arava, in Paran and Tzofar and, to a lesser extent, in Ein Yahav.
  In experiments that were conducted in controlled growth chambers at the Yair Research Station during the 2007/8 growing season, pepper plants were infected with pythium isolated from wilted plants. The plants were grown at average temperatures of 25, 14, 10.5 and 8.6ºC. At temperatures of 14 and 25ºC, no damage was observed on the infected plants, as compared with control plants. In contrast, at 8.6ºC, we observed the death of many plants, beginning two weeks after the infection date. At 10.5ºC, many plants were damaged, but not completely killed. This damage was not seen until many weeks after the inoculation date. The pythium isolate used in this study was sent to a laboratory abroad for identification. It was identified as a new species of Pythium, previously unknown to science. The results of this study provide a good explanation of the relationship between the appearance of the disease, the type of structure used in the cropping system (i.e., net-house or greenhouse) and environmental conditions. In the last decade, relatively high levels of collapse were observed in the 1999/2000, 2004/5 and 2006/7 growing seasons. In each of these seasons, temperatures during December and January were below average for extended periods of time. The move from net-houses to greenhouses in areas that have suffered from winter collapse in previous years has led to a noticeable decrease in the level of collapse. Measurements of soil temperature collected last season in greenhouses and net-houses explain this phenomenon. In areas with similar climates, minimal soil temperatures in greenhouses are higher than those in net-houses.

  שפה English
  מלות מפתח Capsicum
  מחבר Shimon Pivonia, Rachel Levite, Eviatar Etiel
  שנה 2008
  שייכות yzvieli
  תאריך יצירה 14/1/2009
  תאריך עדכון 14/3/2012

  OPEN
• 17

  Dec
  Effects of mycorrhiza on sweet pepper at various stress conditions

  Vegetables

  by Shimon Pivonia, Ph.D.

  Absorption of nutritional mineral elements vital to the plant, by reinforcing the water uptake, by interacting with the plant hormonal balance, by improving soil structure and texture, and by strengthening the plant resistance to soil-borne pathogens. The influence of mycorrhizae (Glomus intraradices) on the response of sweet pepper (Capsicum annuum) to various stress factors has been examined in experiments conducted during the 2007 season. The stress factors investigated included a soil-borne disease – soil inoculation with Pythium, nutrition stress – phosphor shortage, and a combined salt and drought stress. Mycorrhized plants demonstrated a significantly higher resistance to stresses. Mycorrhized sweet pepper plants that were planted on a Pythium-inoculated soil displayed a rapid recovery from the typical inhibition stage followed by a normal growth and development. Likewise, mycorrhized plants exposed to low-phosphor fertilization obtained fruit yield at a similar level as normally fertilized plants. Furthermore, mycorrhized plants that were grown under combined salt and water stress or even with additional low-phosphor fertilization produced yields comparable to that of normally cultivated plants. On the other hand, whenever the pepper plants were not exposed to any type of stress, no advantage of mycorrhized plants could be observed in growth or yield at normal growing conditions. Commercial application of mycorrhizae may bring about a reduction in the water requirements for sweet pepper cultivation and improved plant sustainability under various stresses. Thus, the mycorrhizae can provide the grower with some level of insurance against predicted or unpredicted stress conditions that might occur in the field.

  שפה English
  מחבר Shimon Pivonia, Rachel Levitta, Yael Bar-Lavan, Yoram Kapulnik
  שנה 2007
  שייכות yzvieli
  תאריך יצירה 14/3/2008
  תאריך עדכון 14/3/2012