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• 17

  Dec
  Mycorrhiza pepper stress Yair Arava 2007-8

  Vegetables

  by Shabtai Cohen

  תאריך עדכון 18/1/2009

  This report sums experiment of growing sweet pepper (Capsicum annuum L. cv Celica) while studying the effects of the plants being Mycorrhizal with Glomus intraradices or not at two levels of fertilization and three levels of irrigation. The motivation is to improve growing and irrigation management based on findings that show improved water and nutrients uptake by Mycorrhizal plants in general and G. intraradices in particular. The experiment took place during 2007/8 agricultural season in a greenhouse at Yair Experimental Station in the Arava Valley.
  The studied three levels of irrigation were 50, 75 and 100% relative to the recommended amount by the extension service that is based on evaporation "A" pan data and a crop factor that changes according to the growing stages. The fertilization treatments were the recommended doze that is actually in practice and low in phosphorous. There were two separate treatments with the two different fertilization levels, each contained four replicas of the six possible combinations of irrigation levels (50, 75 and 100%) and the plants being Mycorrhizal or not (Mycorrhizae treatment hereafter). The dependent and measured variables were total yield and the percentage of export out of the total yield. These data were collected throughout the harvesting season, in this report we relate only to the accumulated data at the end of the growing season. Analysis of variance (ANOVA) was done while fitting a general linear model (GLM) to the data: The effect of the fertilization treatment was statistically significant – the recommended fertilization treatment is better than the low phosphorous one. In the low phosphorous treatment, there was not a significant effect to the irrigation level, however, the yield from Mycorrhizal plants was significantly higher than the non Mycorrhizal ones. In the recommended fertilization treatment, both irrigation level and the Mycorrhiza had a significant effect – higher yields were obtained at the 100% irrigation treatment and the Mycorrhizal plants. No interaction was found between the irrigation levels and the Mycorrhizae – one factor cannot compensate for the other one. Another interesting observation was the larger variability in the low phosphorous treatments.
  On the economic side, it seems that the farmer who grows 4.5 hectares of pepper can increase the income by 315,000 NIS in return to a 6,750 NIS investment of adding Mycorrhizae to the plants.

  שפה English
  מחבר Shabtai Cohen, Rivka Offenbach, Shimon Pivonia, Rami Golan, Yoram Zvieli, Yoram Kapulnik, Uri Yermiyaho, Alon Ben-Gal
  שנה 2009
  שייכות yzvieli
  תאריך יצירה 18/1/2009
  תאריך עדכון 18/1/2009

  OPEN
• 17

  Dec
  Pepper day heating Zohar 2007-8

  Vegetables

  by Shabtai Cohen

  תאריך עדכון 24/1/2009

  תיאור מלא In a study conducted at the Zohar Research Station (Sodom Valley), pepper production inside a greenhouse that was warmed during the day, by closing the sides of the greenhouse to trap the heat inside so that the temperature approached 28ºC, was compared with pepper production in a plastic-covered greenhouse with open sides. In previous seasons of this experiment, a positive yield effect was observed in greenhouses in which day-time heating was used. In a continuation of this study, an experiment was conducted in the 2007/8 growing season in two greenhouses. The control greenhouse was continuously ventilated; its sides were left open for the entire cropping season. The treatment greenhouse (day-time heating) was connected to a climate control system (Eldar), which maintained the prescribed temperature by opening and closing the sides of the greenhouse in response to the temperature. The defined temperature thresholds were as follows: sides were closed at 27ºC and opened at 30ºC. Within the framework of the experiment, two pepper cultivars, Celica (Efal) and 7158 (Zeraim Gedera) were transplanted (4 Sept. 2007) into the ground and perlite sleeves (calculated stand = 3.3 plants/m2). Spanish trellising was used. As the crop developed, the plants were maintained according to current standard practices for indoor pepper in the Arava. At the end of the experiment, we did not find that the heating treatment had any positive effect, and this treatment was associated with decreased yield of export-quality fruit. Throughout this experiment, cv. 7158 yielded more than cv. Celica. Apparently, the temperatures in the day-time heating treatment were not high enough to induce the expected positive yield effect. The results collected from this year of the study contradict those collected in earlier years. This is apparently due to exceptionally low temperatures both outdoors and in the day-time heating treatment.

  שפה English
  מחבר Shabtai Cohen, Rivka Offenbach, Ami Madual, Israel Tzabari, Yoram Zvieli, Rami Golan, Eviater Itiel
  שנה 2009
  שייכות yzvieli
  תאריך יצירה 24/1/2009
  תאריך עדכון 14/3/2012

  OPEN
• 17

  Dec
  Evaluation of day time heating of Pepper

  Vegetables

  by Shabtai Cohen

  תאריך עדכון 24/1/2009

  תיאור מלא This experiment was conducted in the context of a four-season experiment at the Yair Research Station that evaluated the effects of day-time heating and night-time heating on pepper (Capsicum annuum) yield and quality. In all of the experiments conducted at the Yair Research Station, no advantage was associated with day-time heating, and intense day-time heating (approx. 35ºC) caused a significant decrease in yield. In contrast, at the Zohar Research Station, heating was found to have a positive effect. (Spanish trellising was used at the Zohar Research Station.) Our assumption for this year’s experiment was that crop yield would be limited by the amount of foliage on the plant, based on an inverse relationship between fruit-setting capacity and the amount of foliage on the plant, following the use of Dutch trellising to limit the amount of foliage. This experiment was conducted using Spanish trellising, in which there is almost no pruning.
  The experiment was conducted at the Yair Research Station, Arava, in four greenhouses that each had an area of 340 m2. In each greenhouse, we transplanted (4 Sept. 2007) pepper plants of the cultivars Celica and 7158, with four replicates of each cultivar. Two of the four greenhouses were heated to a minimum night-time temperature of 12ºC. During the day, an average temperature of 28ºC was maintained in these greenhouses. The third greenhouse was not heated at night, but the day-time temperature in this greenhouse was kept at 28ºC. The fourth greenhouse served as a control. This greenhouse was not heated and its sides were not closed. The temperature in the fourth greenhouse was determined by the prevailing environmental conditions.
  Day-time and night-time heating treatments (minimum 12ºC) did not contribute to the production of high-quality yield in either of the cultivars, in comparison to day-time heating alone. The yield quality of cv. 7158 was not affected by any of the treatments and (for this cultivar) there was no difference between the results of the heated treatments and those of the control. However, an effect on overall yield was observed and day-time and night-time heating had positive yield effects. For cv. Celica, there were no differences between the yields of the heated treatments, but the control treatment yielded significantly less (in terms of overall yield and export-quality yield) than the heated treatments. This significant difference can be attributed to an unusually cold January. The results of this experiment suggest that there are highly significant differences between the responses of different cultivars to heating treatments, and additional cultivars should be evaluated in this context.

  שפה English
  מחבר Shabtai Cohen, Avi Osherovitz, Rivka Offenbach, Yoram Zvieli, Eviatar Itiel
  שנה 2009
  שייכות yzvieli
  תאריך יצירה 24/1/2009
  תאריך עדכון 9/2/2012

  OPEN
• 13

  Dec
  Use of Energy-Saving Systems in Greenhouses at the Yair Research Station, Arava Valley (2008-2009)

  Vegetables

  by Shabtai Cohen

  45
  Use of Energy-Saving Systems in Greenhouses at the Yair Research Station, Arava Valley (2008-2009)

  Use of Energy-Saving Systems in Greenhouses at the Yair Research Station, Arava Valley (2008-2009)

  תחום או ענף אגרוטכנולוגיה; ירקות; פרחים; תבלינים

  תאריך עדכון 27/12/2009

  תיאור מלא Background – To facilitate the continuation and prosperity of agriculture in the Arava, particularly against the background of global economic and climatic change, we must concern ourselves with the use of advanced, innovative technologies to protect crops against damage caused by inclement weather, while allowing continuous fruiting and optimizing fruiting per unit area, to preserve and increase the quality of the fruit or other crop product produced on each unit of cultivated area.
  Goals – The testing and comparison of technologies will allow for energy savings, through the use of integrated systems that make possible improvements in the crop’s growing conditions, by heating and by reducing the relative humidity (RH) inside the greenhouses, as compared with the conventional methods in use today.
  Methods – The experiments were conducted in four cropping structures at the Yair Research Station in the Arava Valley in southern Israel. Each of these cropping structures had an area of 900 m2. The following technologies were tested: 1. Control greenhouse (GH 5). The roof of this greenhouse was covered with polyethylene and the sides were covered with 50-mesh screens. 2. The greenhouse that was equipped with a thermal screen only (GH 2) was constructed of impermeable, reflective sheeting that provided 50% shade. 3. A greenhouse equipped with a thermal screen and the Agam system (GH 3). The Agam system is based on a heat converter that can lower the RH in the greenhouse and supply the additional energy needed to heat the greenhouse. The Agam system pumps the humid greenhouse air through a concentrated salt solution flowing through a matrix of pads. The moisture in the air is then pumped through a condenser, where the latent heat present in the humid air is released into the salt solution. The solution heats up and releases warm, dry air into the greenhouse. 4. Hot-water heating (GH 9). The heater, which has an output capacity of 150,000 kilocalories, includes a heat transfer device based on the flow of hot water through a metal pipe. The heater is powered by natural gas. In this greenhouse, we also installed a thermal screen like the ones installed in buildings 3 and 2. We installed a calorimeter in each of the heated greenhouses, in order to measure the energy demand in the greenhouses. The pepper cultivars Celica (Efal) and 7158 and 7182 (Zeraim Gedera) were transplanted into the greenhouses on 10 August 2008.
  Over the course of the experiment, the temperatures of two fruits from each building and the amount of moisture on the surface of the fruit were evaluated manually once a week. We evaluated green fruits approaching their final size. The evaluation was carried out before the thermal screens were rolled up, usually between 6:45 and 7:00 in the morning, and once an hour for the following three hours. The evaluation of the moisture on the surface of the fruit was done by hand and the moisture level was defined according to four levels: dry, moist, wet or very wet.
  Results and Conclusion- The thermal screen improved the night-time temperature balance and raised the night-time temperature in the greenhouses by an average of 2 to 3.5°C, without any additional energy input from any external (artificial) source. This contribution was accompanied by an increase in the amount of moisture in the building, which increased the cracking of the pepper fruit. The Agam system provided an average energy savings of 60%, as compared to the parallel heating system that used warm water to heat the greenhouse. Both of these systems involved the use of a thermal screen. The RH in the building heated using the Agam system was lower than that in the building heated using the conventional hot-water heating system. This difference between these two systems will increase the more tightly the buildings are sealed. Of the tested cultivars, cv. Celica is most resistant to cracking and cv. 7182 is most susceptible. The highest levels of cracking were observed in the greenhouse with the thermal screen (and no heater), and this corresponds to the wetness of the fruit and the high humidity observed in this building, as compared to the other buildings. The heating systems should be tested in an additional season, in order to characterize the distributions of heat and humidity associated with the different heating systems. The performance of the heating systems should also be tested over a colder winter, as this past winter was quite mild.

  שפה English
  מחבר Shabtai Cohen, Rivka Offenbach, Dorit Hashmonai, Dudu Elkayam, Avi Osherovitz, Gad Asaf, Moshe Maroko
  שנה 2009
  שייכות yzvieli
  תאריך יצירה 27/12/2009
  תאריך עדכון 9/2/2012

  OPEN