Research

Filter results

Department
Clear
Author
Type
Dates
Clear
FROM
TO

Research

  • 17
    Dec
    Winter collapse of pepper 2007/8
    Plant Protection, Vegetables

    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
    Evaluation of pepper rootstock lines 2007/8
    Vegetables

    תאריך עדכון 14/1/2009

    תיאור מלא The decreased use of chemical soil treatments, the decreased variety of chemicals applied, increased nematode damage and a lack of nematode-resistant cultivars have all increased the need for appropriate rootstock lines for commercial production of conventional and organic pepper. In an experiment that was conducted during the 2007/8 growing season in screen-houses in the organic section of the Yair Research Station (Arava region), we tested new rootstock lines, in comparison with the veteran rootstock line, 23, in an effort to identify pepper rootstock lines that exhibit vigorous vegetative growth under different growing conditions. In particular, we evaluated the performance of the plants in the presence of salinity, low winter temperatures, diseases and soil pests (nematodes). We examined the following new rootstock lines: Capital, 72001 and 72002. During the growing season, the plants from cultivars 7158 and Vergasa that had been grafted onto rootstock line 23 produced many side branches. These branches were removed at a late date, which damaged the yields of these graft combinations and this rootstock line. Overall, ungrafted 7158 yielded 8.9 kg/m2, as compared to the 7.7 kg/m2 produced by 7158 grafted onto rootstock line 23. The difference in these yields is due to the side branches mentioned above. A similar negative yield effect was observed for plants in which ‘Vergasa’ was grafted onto rootstock line 23. These grafted plants yielded 7.4 kg/m2, as compared to the 8.0 kg/m2 produced by ungrafted ‘Vergasa’ plants. The quantities of fruit suitable for export and the percentages of the total crop that were suitable for export were also similar. Grafts of 7158 onto the rootstock lines 72001 and 72002 produced overall yields of 8.4-8.6 kg/m2, similar to the yield of the ungrafted 7158 plants (8.9 kg/m2). The combination of 7158 grafted onto ‘Capital’ rootstock produced an overall yield that was less than 7.4 kg/m2. The results involving export quality were similar.

    In light of the problems that arose as a result of the rapid sprouting of side branches in rootstock line 23, it is difficult to make any conclusions regarding the grafts of 7158 and ‘Vergasa’ onto this control veteran rootstock line. Of the three new rootstock lines that were evaluated (Capital, 72001 and 72002), the lines 72001 and 72002 both performed well. We recommend continued evaluation of these two rootstock lines, in comparison with the outstanding control rootstock from previous years, 23. Following transplanting, it is important to diligently remove side branches as they are produced by the rootstock line. We recommend future evaluations of new rootstock lines with high levels of resistance to viruses, including resistance to the TSWV virus. It is important that the rootstock line and graft have similar virus resistance profiles, to prevent the collapse of grafted plants as a result of incompatible resistances, a phenomenon that is found in tomato grafts.

    שפה English
    מלות מפתח Grafted Capsicum
    מחבר Rivka Offenbach, Ariel Yafe, Israel Tzabari, Yoram Zvieli, Dudu Elkayam, Svetlana Gugiu,Rami Golan
    שנה 2008
    שייכות yzvieli
    תאריך יצירה 14/1/2009
    תאריך עדכון 14/3/2012

    OPEN
  • 17
    Dec
    Effect of the Use of Tomato Transplants from a Nursery in Sussiya on Early Fruit setting 2007-8
    Vegetables

    תאריך עדכון 16/1/2009

    תיאור מלא The marketing period for exported tomato is short, from November until April. Growers usually transplant beginning in September, when the weather is warm and not conducive to fruit setting (average air temperature above 35ºC). Transplanting during this period is problematic because conditions for fruit setting (for the fruit intended for export) begin to prevail in mid-October. Early transplanting can lead to problems with fruit setting, and these plants are also exposed to a number of different pests which are very active during this period, particularly the virus vector whitefly and mites. In organic production systems, hormones can not be sprayed and the majority of the growing areas (for both the organic and conventional crop) are not equipped with cooling systems. During this short marketing season, the export crop is small and its profitability has declined from year to year.
    During the summer of 2006/7 season, a project was begun to evaluate the possibility of earlier transplanting in the Syro-African Rift Valley. This research found that earlier transplanting was only successful in structures that were physically cooled using a fan and pad evaporative cooling system. In light of this finding, a decision was made to evaluate the possibility of later transplanting of slightly older tomato plants at a later date. Fruit setting would be induced in the nursery under cooler conditions, prior to transplanting, to ensure the continuous setting of quality fruit and decreased production costs.

    The present work was conducted at the Yair Research Station during the 2007/8 season. When young tomato plants (cv. Shiran and Meital – Hazera Co.) from different cohorts from the Sussiya nursery in the Hebron Mountains, where temperatures are lower than those in the Arava, were transplanted into organic greenhouse plots 15 days later than usual (25 Sept. 2007. vs. 10 Sept.), there was no difference between the yields of the two cultivars. For cv. Meital, the overall yield and the yield of clusters for export were greater for the 45-day-old plants that were transplanted on 25 September than for the standard plants that were transplanted earlier. The plants transplanted at the later date produced fruits that were lighter (weight of individual fruits) than those of the plants transplanted at the earlier date. Early fruit setting, which allowed for a harvest in December, was only observed in the regular plants transplanted at the later date, and was less significant for the plants that were transplanted when they were 45 or more days old than for the control. There was no advantage to transplanting 60-day-old plants instead of 45-day-old plants. For 45-day-old transplants of cv. Meital, the overall yield for the later transplanting date was greater than the overall yield for the earlier transplanting date. However, the yields of clusters for export were similar for the two planting dates. No early fruit setting was observed for the second transplanting date.

    Delaying the transplanting of slightly older tomato plants raised in Sussiya (cv. Shiran and Meital) by 15 days did not lead to a significantly earlier harvest, had no negative effects on overall yield or yield quality and led to increased yields when the transplanted plants were 45 days old. There was no advantage to transplanting 60-day-old plants instead of 45-day-old plants.

    שפה English
    מחבר Rivka Offenbach, Ariel Yafe, Yoram Zvieli, Rami Golan, Israel Tzabari
    שנה 2009
    שייכות yzvieli
    תאריך יצירה 16/1/2009
    תאריך עדכון 14/3/2012

    OPEN
  • 17
    Dec
    Ranunculus vernalization in the Arava
    Flowers

    תאריך עדכון 18/1/2009

    תיאור מלא Geophytes production in Israel has increased over the past several years, thanks to a relative marketing advantage during periods in which competing nations have not been active in this market. Following tests of a number of corms and bulbs of flower crops conducted by R&D Central and North Arava, it became clear that taking advantage of and adopting sophisticated cropping infrastructure for geophyte crops, such as the use of greenhouses, growing the plants in trays instead of in the ground, and supplemental heating and lighting, makes it possible to move up the flowering and harvest seasons, relative to other parts of the country, to produce positive results. These results have transformed geophytes in the Arava into an additional crop in the portfolio of local flower crops and a worthwhile alternative to least profitable large-scale crops. When Ranunculus crops, specifically Elegance cultivars, were first brought into commercial production, they were thought to hold great economic potential, despite their late-ripening flowers. In work that was conducted at the Yair Research Station in the Arava over three growing seasons (2005/6, 2006/7, 2007/8), we tested the effects of different vernalization treatments on the timing of flowering. These treatments were: standard vernalization (4ºC for 4 weeks and 9ºC for 1 week), Italian vernalization (gradual cooling of the corms to 13ºC for 1 week, 9ºC for an additional week, followed by 4ºC for one week and gradual warming) and transplanting into seed trays. Despite the fact that we had anticipated that transplanting into trays might be advantageous, this treatment was no better than regular transplanting. Standard vernalization led to early flowering, as well as the production of a larger quantity of flowers. Transplanting into trays could be advantageous in situations in which the planting area could not be prepared in time, or when the goal is to transplant earlier than is customary. In this situation, it is important that the young plants be sufficiently hardy before they are taken from the ground, and it is also important to take into account the likelihood of establishment problems among a portion of the transplanted plants.

    שפה English
    מלות מפתח NURIT
    מחבר Maayan Plaves Kitron, Keren Elbaz, Avi Osherovitz, Dorit Hashmonai, Iris Yedidya, Gidon Luria, Amnon Navon
    שנה 2009
    שייכות yzvieli
    תאריך יצירה 18/1/2009
    תאריך עדכון 14/3/2012

    OPEN