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• 9

  Dec
  Application of organic matter in trenches for pepper production

  Soil and Water, Vegetables

  by Shlomo Kramer

  21
  תחום או ענף ירקות
  תאריך עדכון 23/2/2012

  Application of organic matter in trenches for pepper production
  Shlomo Kramer – Field Service, Extension Service, Negev Region, Ministry of Agriculture and Rural Development
  Shabtai Cohen, Rivka Offenbach, Yoram Zvieli – Central and Northern Arava R&D
  Israel Zer – Moshav Paran
  E-mail address for correspondence: shlomo@arava.co.il

  Differences in soil composition along the length of plots lead to non-uniform development of plants, which leads to variation in yield. In order to cope with this problem and obtain uniform crop growth throughout the plot, a trench is dug in the center of the plot. The trench is filled with homogenous material such as tuff, Perlite or stabilized organic matter. There are a number of different variations on this technique. Organic matter is the cheapest material, is easy to apply and also makes a significant contribution of a range of nutrients for the plants.
  Two application methods were evaluated in pepper during the 2010/11 growing season at the Zer farm at Moshav Paran. This study evaluated trenches filled with organic matter (14 m3 per dunam) over which two lines of drippers were set out and very shallow “trenches” in which the same amount of organic matter was applied.
  At the beginning of the season, the plants in the beds with the deeper organic matter-filled trenches were in poor shape relative to the plants in the beds in the shallow-trench treatment, apparently due to the salinity of the organic material. After two harvests, an absolute difference between the two treatments was observed in two different cultivars. In the shallow-trench treatments, cv. Tirza yielded 2 tons/dunam (=kg/m2) and cv. Imperio yielded 1.75 tons/dunam. In contrast, in the treatment with the deeper trenches, cv. Tirza yielded 0.85 tons/dunam and cv. Imperio yielded 0.23 tons/dunam. This difference persisted throughout the growing season. For cv. Imperio, the highest yields were 12 tons/dunam in the shallow-trench treatment and 10.4 tons/dunam in the organic-matter treatment. The cv. Tirza yielded 13.3-11.2 tons/dunam.
  Soil analyses, which were carried out every three weeks, revealed a higher level of salinity in the 0–15 soil layer than in the 15–30 soil layer in both trench treatments. Levels of phosphorous and potassium were high throughout the season. In the organic matter-filled trench treatment, the level of nitrogen remained high at the end of the season. The electrical conductivity of the soil solution, which was assessed using partially automatic pumps, increased from early September through the end of October at depths of 15 and 30 cm and reached 4-5 dSm/meter. This is also the period during which the amount of water needed by the crop peaks and, apparently, the level of irrigation was not sufficient to fully rinse the accumulating salts from the root zone.
  This experiment demonstrates the importance of using properly processed and stabilized organic matter to fill trenches that were not loosen-cultivated. The mixing of the organic matter in the trench with the soil, by shallow tillage, ensures proper, rapid crop development even when the organic matter has not been stabilized as well as it could have been or in situations in which time limitations force growers to plant shortly after organic matter has been applied to the trenches.

  שפה English
  מחבר Shlomo Kramer, Shabtai Cohen, Rivka Offenbach, Israel Zer
  שנה 2011
  שייכות yzvieli
  תאריך יצירה 23/2/2012
  תאריך עדכון 23/2/2012
• 9

  Dec
  Effect of population density on platy fish (Xiphophorus maculates)

  Aquaculture

  by Nitzan Hevlin

  20
  תחום או ענף דגים
  תאריך עדכון 14/3/2012

  Effect of population density on platy fish (Xiphophorus maculates)
  Nitzan Reiss Hevlin, Tal Gur, Moti Userovich and Dan Popper - Central and Northern Arava R&D
  E-mail address for correspondence: nitzanr@arava.co.il

  Abstract
  Platyfish (Xiphophorus maculates) are a popular species for home aquariums; these social animals live in schools and are pretty. They are omnivorous and give birth to live young. On farms, the faster the fish grow, the more crowded they get and the lower the costs to the grower — and the greater his profit margin. The process of ramping up production requires a significant increase in the number of fish per unit volume. There is a delicate balance between increased density, which allows for maximal use of the area, and preserving the health of the fish and their growth rate. Density is a source of chronic stress that is expressed in different ways depending on the type of fish, their age and their gender.
  In an experiment conducted at the Yair Research Station during 2010/11, we evaluated the effect of the density of fish in an aquarium on their growth rate and survival. We did not find any difference in the growth of the fish at different population densities. However, we did see a difference in the survival rate at a density of one fish per liter as compared to 2.5 fish per liter.

  שפה English
  מלות מפתח Ornamental fish, water quality
  מחבר Nitzan Reiss Hevlin, Tal Gur, Moti Userovich, Dan Popper
  שנה 2011
  שייכות yzvieli
  תאריך יצירה 14/3/2012
  תאריך עדכון 14/3/2012
• 9

  Dec
  Use of concentrated brine for raising clownfish (Amphiprion ocellaris)

  Aquaculture

  by Nitzan Hevlin

  19
  תחום או ענף דגים
  תאריך עדכון 14/3/2012

  Use of concentrated brine for raising clownfish (Amphiprion ocellaris)
  Nitzan Reiss Hevlin, Dan Popper, Tal Gur, Moti Userovitch – Central and Northern Arava R&D
  E-mail address for correspondence: nitzanr@arava.co.il

  Abstract
  The market for ornamental saltwater fish has developed greatly in recent years and the demand for fish raised in captivity has increased. Clownfish (Amphiprion) are in great demand in the European market, where they are sold as ornamental fish for reef aquariums. They are valued for their pretty form and bold color, as well as their ability to live together with invertebrates in an aquarium. In recent years at the Yair Experimental Station of the Arava R&D Authority, a protocol has been developed for breeding and raising eight species of clownfish, including the most popular species, A. ocellaris. Currently, researchers at the Arava R&D Authority are focused on improving growth and breeding, adding new species to the set of saltwater fish currently raised in the region and reducing production costs. The main cost associated with raising saltwater ornamental fish in artificial environments is the cost of the water in which the fish are kept. Seven large desalination installations are currently used in the Arava to provide drinking water for local residents. Large amounts of brine flow from each of these installations to the sewer system. This brine is a byproduct of the desalination process and contains salt concentrations that are twice that of the local pipeline water. A previous study conducted at the Yair Experimental Station in 2010 examined the growth rate and survival of young clownfish raised in brine that was supplemented with sea salt as compared with those of fish raised in desalinated water or pipeline water supplemented with sea salt. There was no difference between the health and growth rate of the fish in the different treatments.
  In the experiment on which we are currently reporting, which was conducted in 2011, we evaluated the growth rate and survival of clownfish raised in brine concentrated to a salinity level of 0.25 ppt. We did not notice any difference in the growth of the fish, but there was a significant difference in terms of survival.
  Histological examination of the gills of these fish did not reveal any significant pathology in any of the treatment groups. The only difference between the groups was the form and quantity of chlorine cells.

  Acknowledgements
  We thank the JCA Charitable Foundation for their financial support for this research. Thank you to Prof. Shanan Herpaz and Dr. Avner Canaani for their help planning the study. Thank you to Dr. Dina Zilberg, Dr. Gilat Sharon and Tamar Sini for examining the fish after the experiment. We thank the Arava staff of Mekorot, especially Yuval Plaout and Yoav Moyal for their cooperation, patience and generous assistance. We thank the staff of the Hetzva Field School for their understanding and patience.

  שפה English
  מחבר Nitzan Reiss Hevlin, Dan Popper, Tal Gur, Moti Userovitch
  שנה 2011
  שייכות yzvieli
  תאריך יצירה 14/3/2012
  תאריך עדכון 14/3/2012
• 9

  Dec
  Enriching feed for molly fish (Poecilia velifera) with pigments

  Aquaculture

  by Nitzan Hevlin

  18
  תחום או ענף דגים
  תאריך עדכון 14/3/2012

  Enriching feed for molly fish (Poecilia velifera) with pigments
  Nitzan Reiss Hevlin, Tal Gur, Moti Userovich and Dan Popper – Central and Northern Arava R&D
  E-mail address for correspondence: nitzanr@arava.co.il

  Abstract
  The color of fish has a determinative effect on their beauty and how in demand they are in the market. A diet that includes pigments affects the color of the fish. In nature, the fish acquire pigments from the algae and aquatic microorganisms that they eat, but in closed systems used for breeding ornamental fish, it is customary to add coloring agents to the feed. In a series of experiments carried out at the Yair Experimental Station during 2011, we evaluated different types of coloring agents, both natural and synthetic, to determine which should be added to the fish feed. In a previous experiment in which coloring agents were added to the feed of molly fish (Poecilia velifera), good results were obtained from three different coloring agents: Haematococcus pluvialis, Capsantal and carophyll pink. Of these, we included the latter two in a further experiment that also included three types of feed. We found that for gold and orange mollies, the coloring agent Capsantal and BioMar feed provide the best results.

  שפה English
  מחבר Nitzan Reiss Hevlin, Tal Gur, Moti Userovich, Dan Popper
  שנה 2011
  שייכות yzvieli
  תאריך יצירה 14/3/2012
  תאריך עדכון 14/3/2012