Research

Filter results

Research

• 17

  Dec
  Pepper irrigation based tensiometers’ signals

  Vegetables, Soil and Water

  by Shlomo Kramer

  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
• 18

  Dec
  Response of truss tomato yield to above-optimal average greenhouse temperatures and to soil bedding features

  Vegetables

  by Eviatar Ityel

  תחום או ענף ירקות
  תאריך עדכון 18/2/2008

  תיאור מלא Truss tomatoes (varcv. PrincesNesicha) were planted on June 20, 2005, in a cooled greenhouse and were grown for 176 days, until mid-December. Harvest started 61 days after planting and lasted 115 days. Mean fruit yield per greenhouse was 17.8 Kg•m-2, with an average harvest rate of 4.7 Kg•m-2 per month for the entire harvest period. Until the beginning of November, the average daily temperature was above 18°0C. The average daily temperature increased along the rows in accordance with the distance from the cooling pad (0.03°0C•m-1, an average for the entire cooling period). The decrease in the relative yield as a result of the temperature rise along the row was -7%•°0C -1, largely due to a decline of 10%•°0C -1 in the number of harvested clusters. These parameters agree with the results of a previous experiment (2004).
  This study indicates that the relative yield for a season largely depends on the average daily temperature and is predictable where the latter exceeds 18°0C, according to the following formula: .
  The effect of temperature on fruit weight was not linear. Up to 24.3°0C, the fruit weight decreased, however it increased again with the climbing average daily temperature above 24.3°0C, although the number of seeds per fruit kept decreasing linearly. Fruit quality also declined with temperature rise; the portion of fruit disqualified for export and the rate of black-end-rot fruit weight have increased.
  Plants grown on nutrition ducts containing tuff subsoil yielded 18% more than plants on regular soil. Most of that difference was attributed to a higher number of clusters. Surprisingly, temperature rise along the row had no adverse effect on the yield of truss tomato plants grown on nutrition ducts, indicating for improved edaphic conditions that enhanced the ability of the plants to cope with increasing temperatures.

  שפה English
  מחבר Eviatar Itiel, Zahi Rimon, Moshe Rimon, Yoram Zvieli, Rivka Ofenbach
  שנה 2007
  שייכות Israel Tsabari
  תאריך יצירה 18/2/2008
  תאריך עדכון 18/2/2008
• 18

  Dec
  Response of sweet pepper yield to average super optimal greenhouse temperatures

  Vegetables

  by Yoram Zvieli

  תאריך עדכון 18/2/2008

  תיאור מלא Cultivation under controlled temperature (heating and cooling) comprises a small yet growing portion of the sweet pepper industry in the Arava Valley. The understanding of the precise effects of temperature on cropping may provide further optimization of the energy and water inputs in sweet pepper greenhouses. (last sentence not in editted summary) In the present study, we tested the response of sweet pepper yield to the average day temperature above 21ºC as created along the rows by a cooling air stream moving north to south in the greenhouse. The gradient of average temperature from the wet cooling pad to the ventilators at the southern wall of the greenhouse was 0.5ºC•m-1. Sweet pepper plants (var. Selica) were planted on January 20, 2005, and grown during 300 days. Fruit harvest began 80 days after planting and continued thereafter. The operation of the cooling system took place between May and October 2005. Temperature was continuously monitored along plant rows using combined sensors and data-loggers. The results indicate for a special sensitivity of the sweet pepper yield to ascending temperatures above 21ºC; the higher the average temperature above this threshold the lesser the yield (at a rate of 15%•ºC-1). The difference in yield between the lowest and the highest average temperature (14m vs. 52m from the cooling pad) was 26% (19.1 vs. 14.2 Kg•m-2, respectively), was considerably greater than that obtained in the year 2004 experiment (August planting). Fruit size significantly responded to the increase in the average temperature 40 days before harvest by a decline rate of 5%•ºC-1 (R2=0.84), whereas the response of the number of fruits was inconsistent with temperature changes. Fruit quality was not affected by average temperature gradient. The relative humidity did not affect sweet pepper yield parameters. The results of the present study and others strongly indicate for a direct negative though complex effect of high temperatures on sweet pepper yields. Modeling tools are being used now to further analyze and understand that effect.

  שפה English
  מחבר Eviatar Itiel, Zahi Rimon, Moshe Rimon, Yoram Zvieli, Rivka Offenbach
  שנה 2007
  שייכות Israel Tsabari
  תאריך יצירה 18/2/2008
  תאריך עדכון 18/2/2008

  ITYEL
• 18

  Dec
  Examination of an innovative technology for soil-less culture of vegetable crops, Yair Station, 2005/6

  Vegetables

  by Rivka Offenbach

  תאריך עדכון 19/2/2008

  תיאור מלא An innovative soil-less method for horticultural crops developed by A. Winter (Kfar Maimon) exhibited a significant improvement of the water use efficiency at the good water quality of the northern Negev, with no reduction in yield and quality. In the present study, the implementation of the method was examined using the local brackish (2.5-2.8 dS/m, 450 mg Cl/L) irrigation water of the Arava. 550 sweet pepper seedlings (var. Celica) were planted (Sep. 4, 2005), one plant in each 10-L container, occupying 160 m2 (3.3 plant/m2). Each container had an open outlet for drainage few cm from its bottom, allowing for a constant water reservoir, which can be drained by an additional controllable outlet. Irrigation was controlled using a representative, continuously weighed plant. The performance of the soil-less culture plants was compared to that of neighboring conventionally grown plants planted in the soil in the same greenhouse. Early in the growing season, salt buildup, particularly at the upper volume of the containers, was recorded. The method does not provide efficient drainage and salt bleeding; soil EC values varied at 5-7 dS/m already in November. The water quantity consumed by container-grown plants was 595 in comparison to 875 mm per season averagely consumed by soil-grown pepper plants. The total yield of the soil-less plants peaked on December, while the control did so 3 months later. The exportable yield of the "Winter"-plants was less by 1 Kg/m2 than the control; fruit were smaller (160 vs. 170 g) and fewer exportable fruits were produced (33 vs. 38 fruit/m2, respectively). In conclusion, the "Winter" soil-less method is obviously a water-saving one, which is most likely to succeed better where water quality is of higher quality. However, it does not fit the salinity levels of the Arava water sources; plants display stress symptoms, the yield distribution along the season is undesirable, and the quantity and quality are significantly reduced. Yet, some lessons can be taken from the method to improve the performance of pepper cultivation in the Arava.

  שפה English
  מחבר Rivka Offenbach, Shabtai Cohen, Shay Aharon, David Elkayam, Israel Zabari, Rami Golan, Aharon Winter
  שנה 2007
  שייכות Israel Tsabari
  תאריך יצירה 19/2/2008
  תאריך עדכון 19/2/2008