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  • 17
    Dec
    Salinity leaching requirements A case study for bell pepper
    Vegetables, Soil and Water

    תחום או ענף אגרוטכנולוגיה; ירקות
    תאריך עדכון 23/4/2008

    תיאור מלא Maximization of crop yields when the salinity of irrigation water is high depends on providing plant transpiration needs and evaporative losses, as well as on maintaining minimum soil solution salinity through leaching. The effect of the amount of applied irrigation water was studied regarding transpiration, yields, and leaching fractions as a function of irrigation water salinity. Bell pepper (Capsicum annum L. vars. Celica and 7187) in protected growing environments in the Arava Valley of Israel was used as a case-study crop to analyze water quantity-salinity interactions in a series of lysimeter, field and model simulation experiments. Leaching fraction was found to be highly influenced by plant feedback, as transpiration depended on root zone salinity. Increased application of saline irrigation water led to increased transpiration and yields. The higher the salinity level, the greater the relative benefit from increased leaching. The extent of leaching needed to maximize yields when irrigating with saline water may make such practice highly unsustainable.

    שפה English
    מחבר Alon Ben-Gal, Eviatar Ityel, Lynn Dudley, Shabtai Cohen, Uri Yermiyahu, Eugene Presnov, Leah Zigmond, Uri Shani
    שנה 2008
    שייכות yzvieli
    תאריך יצירה 23/4/2008
    תאריך עדכון 14/3/2012

    OPEN
  • 17
    Dec
    Amblyseius swirskii PEPPER 2006-7
    Plant Protection

    תאריך עדכון 10/5/2008

    תיאור מלא So far, no biological means against the broad mite (Polyphagotarsonemus latus) could be provided by natural enemies and its eradication was performed using chemicals or sulfur containing pesticides. In a study conducted during the 2006/7 season in Yair Station in the Arava Valley, the feasibility of using the predatory mite A. swirskii against the broad mite was investigated in sweet pepper (Capsicum annuum) grown in walk-in tunnels. In addition, the effects of this predator on the population of the western flower thrips (F. occidentalis) and on the severity of damage to the fruit were evaluated. The predatory mite performed a high level of broad mite eradication, equal to that of chemicals, when applied at a population of 100 individuals/m2 two weeks after planting in a plot that had been naturally infested by high levels of whitefly and broad mites. Also, the predatory mite lessened the level of the thrips population, particularly on the autumn and the early winter. A reduction in the damage caused by thrips to the pepper fruit was observed as well. Later on, however, with the decline of the predatory mite population during the winter, and along with the rise in the thrips population then, the damage to the fruit increased again. It appears that A. swirskii may be used as an auxiliary tool, complementary to Orius insidiosus for the reduction of the thrips level in the field, but it should not be considered as the sole solution.

    שפה English
    מחבר Carmit Tal, Phyllis Weintraub, Sophia Kleitman ,Shimon Pivonia, Yael Bar-Lavan ,Shimon Steinberg
    שנה 2008
    שייכות yzvieli
    תאריך יצירה 10/5/2008
    תאריך עדכון 14/3/2012

    OPEN
  • 17
    Dec
    USE OF TENSIOMETER IN PEPPER CULTIVATION IN THE ARAVA VALLEY
    Soil and Water, Vegetables

    תאריך עדכון 15/5/2008

    תיאור מלא The operation of irrigation systems according to the changing soil water potential may suggest a regime that follows the physiological state of the crop, thus being more accurate and water saving. A sensor, which represents the soil water content on-line, may provide the data required for automatic update of the irrigation program. An experiment was executed during the 2006/7 season in a sweet pepper greenhouse in Paran (Zer farm) in order to test the effects of the applied water quantity when irrigation signal comes from the tensiometer ,on the irrigation frequency, plant development and yield, and on the seasonal water consumption. Three independent treatments were examined, were the amounts of 2, 3, and 4 mm (L/m2) were applied upon a signal. In order to learn the crop response to irrigation amounts, two additional treatments were operated according to the sensor of the 3 mm treatment (dependent), in one 2mm were applied and in the second 4 mm.
    The average daily quantity of irrigation water had a significant effect on the plant height already at the beginning of October, two weeks after the treatments had been administered; plants receiving the least quantity, 2 mm while the other were getting 3 mm and more, were remarkably shorter than the others. The effect on the yield was obvious on early February, when the 2 mm treatment obtained only 5.6 as compared to the 6.5 kg/m2 obtained by the others and the difference remained as such to the end of the season. In the independent treatments, the average daily water quantities were equal from late November, gradually declining to a level of 1-1.5 mm on late January. The irrigation frequency was the lowest at the 4 mm, and the highest at the 2 mm treatment. Measurements of the soil extracts indicated on mid January nitrogen depletion at the two treatments of 2 mm per pulse. No indication for any increase in soil solution EC at the rhizosphere (10-15 cm deep) was found.In Soil samples taken on 18/01/07 the Chloride concentration at the layer 0-15 cm was higher in the 2 mm dependent treatment.
    Our results demonstrate that the operation of an irrigation system upon a signal of a soil-moisture sensor is feasible and allows for an efficient and appropriate management of the irrigation regime. The method, whenever adopted by the growers, will surely bring about significant water saving, as related to the present irrigation habits. Notably, however, is the fact that an average daily water quantity smaller than 3 mm from mid September to mid December has slowed down the plant growth rate and has brought about a yield decrease.

    שפה English
    מחבר Shlomo Kramer, Israel Zer, Elisha Kenig
    שנה 2008
    שייכות yzvieli
    תאריך יצירה 15/5/2008
    תאריך עדכון 14/3/2012

    OPEN
  • 17
    Dec
    Pepper irrigation based tensiometers’ signals
    Vegetables, Soil and Water

    תאריך עדכון 30/12/2008

    תיאור מלא Tensiometers and soil-water content sensors can provide continuous reliable information regarding the temporal and real time changes of the water content within the root-zone. The changes of water content within the soil, result from environmental and vegetal effects on the rate of water uptake by the plants and the deep percolation to deeper depths of the soil. Incorporation of such equipment in irrigation control systems will enable a real time response to a decrease of soil water amounts and to better management of the irrigation, i.e. amounts and frequencies. A field study was carried out in 2006/7 seasons at Israel Zer's farm in Paran. In this study, the effect of different irrigation quantities on the overall characteristics of the irrigation and yield was evaluated under the same "turn on" matric potential that was transmitted from tensiometers and initiated the irrigation. The results showed that an automated irrigation in the field can supply the required water amounts according to the daily weather changes. The daily average water quantities that were given to the plots decreased together with the shortening of day time and the decrease of temperatures. Irrigation frequency also changed according to the water amount that was supplied once the "turn on" signal was sent from the tensiometer to the irrigation system. The lowest irrigation quantity resulted in shorter intervals between irrigations. Irrigation efficiency was higher in all treatments without affecting yields.
    The objective of the 2007/8 experiment was to evaluate the implication of applying the same water amount at different levels of soil-water matric potentials In order to estimate the appropriate range for the "turn on" values, a single water application was given in the afternoon at the end of August 2007. Three potential values were chosen along the lineof the tensiometer reading that represents the change in soil water contentent. The lowest value was 10 milibars above the value once night deep percolation ended, The other two values were 10 milibars difference from each other. An amount of 3.65 mm( ) was given each time an irrigation event was triggered. The operation of the automated irrigation treatment started on 1/9/2007. During September and October, irrigation frequency was once a day where only in the lowest "turn on" value treatment there were few twice a day irrigations. The annual water amounts were 989 mm, 962 and 864 in the lowest, medium, and highest "turn on" matric potential values respectively. Total yield was 10 ton dunam-1, 9.3 and 9.2 respectively – all values are not significant from each other.
    The highest "turn on" value treatment was the most efficient during the whole season. Most water saving was after the end of November. In this time of the season, water uptake decreases with the decrease of temperatures and the shortening of the day. Also the intervals between irrigations increased.
    The advantage of irrigation management based on soil-water measurements is the adjustment of the water amounts and timing to the plants' demands according its size, its growing stage and the weather. The fact that the decrease in the annual water amounts didn't result in a decrease of the yield might be attributed to the appropriate timing of irrigation. Note that the overall water amounts in this season were lower than other years because of the sever frost events that shortened the season by one month.

    שפה English
    מחבר Shlomo Kramer, Israel Zer, Elisha Kenig
    שנה 2008
    שייכות yzvieli
    תאריך יצירה 30/12/2008
    תאריך עדכון 14/3/2012

    OPEN