Thanks to S. Cohen, H. Yehezkel, D. Shmuel, E. Matan and M. Dinar who contributed to this article.

Background

The Southern R&D Center in Israel specializes in greenhouse crops and serves as the Israeli center for greenhouse research and development. The center aids in seeking agricultural income resources for farmers in the Negev region.

Strawberries are a common winter crop and a significant agricultural product in Israel representing a key source of income to many farmers. Most strawberry growth is concentrated in central Israel where they are grown in low polyethylene covered tunnels.

The aim of the present R&D study was to develop novel methods to grow strawberries in greenhouses in the western Negev region, which is characterized by unique climate conditions in the winter (relatively high radiation and high temperatures in comparison to other regions in Israel).

Research Goals

• Increase strawberry yields per area unit
• Centralize strawberry crop at peak season of export-marketing prices
• Produce a top quality product
• Create conducive working conditions
• Reduce the use of disinfesting compounds

Research Targets (Experimental Process)

• Plant preparation
• Growth medium
• Plant containers
• Timing of planting
• Selecting the appropriate varieties
• Planting stands and configuration of the plants in the greenhouse

Plant Preparation

Plant development and yield greatly depend on plant quality and therefore it is essential that plants be disease-free and in optimal physiological condition. The selected growth method was based on growing mother plants in containers with the growth medium on elevated beds.

Mother plant shoots grown in the medium developed air shoots that never touched the soil. Buds that developed on the shoots were detached about a month prior to planting in the production greenhouse and planted in printed trays containing growth medium. Buds tend to root rapidly and approximately one month after planting, the plants were ready for planting in the production greenhouse. It should be noted that growth conditions are critical and quality plants should be grown under low night temperatures in order to obtain good differentiation and development after planting.

Growth Medium

The following growth media were examined: perlite; tuff; a mixture of tuff and compost; coconut and peat. Selecting a suitable medium is critical for several reasons:

• Suitability for plant growth and for controlling watering and fertilization
• Cost
• Weight

Conclusion: It is possible to grow strawberries in various types of media. The medium that was found to be most suitable is a mixture of coconut + 15% foamed plastic and high quality peat.

Plant Containers

Installation and hanging of growing containers on the greenhouse construction is undoubtedly the most important factor for success in the method used. The requirements of the containers are:

• Limited volume
• Good drainage capacity
• Light, easy to hang and simple to move on the greenhouse construction
• Cost effective
• Easy to handle

Conclusion: When selecting growing containers, it is important to consider provision of uniform growth conditions to all the plants, i.e. irrigation, nutrition and uniform exposure to radiation.

Growing Strawberries in Greenhouses

Four main methods were examined on how to grow strawberries in the greenhouse:

Strawberry Grown in a Column

• Advantage of method: Large number of plants per area unit.
• Disadvantage of method: Pronounced dissimilarity between plants in the upper and lower parts of the column. This dissimilarity is due to differences in the radiation intensity and the amount of fertilizer reaching the plant.
• Conclusion: This method is inferior.

Strawberry Grown in Terraced Beds - "Steps"

• Advantage of method: Large number of plants per area unit.
• Disadvantage of method: Upper part of bed is shaded and growing conditions are not uniform.
• Conclusion: This method is inferior. 

Strawberry Grown in Elevated Beds with Bases Attached to Soil

• Advantage of method: Simple and easy to operate.
• Disadvantage of method: High cost, expensive utilization of greenhouse area (high ratio between path area and bed). This method offers no economic justification for commercial production.

Strawberry Grown in Beds Hanging on Constructions

• General Description of method: Strawberry is grown in a detached, small volume medium in beds on the greenhouse construction, 80 - 120 cm above the soil surface. Strawberry plants are planted in the growth medium in plastic foam containers (16 l/m3).
• The container is placed on a drainpipe, which enables drainage and collection of the drained water.
• Total length of beds in 1000 m2 is about 2000 meters.
• Advantage of method: Simple, easy and convenient to operate, with a large number of plants per unit area.
• Disadvantage of method: The greenhouse construction requires special support.

Summary & Conclusion

Hanging beds were found to be most suitable for strawberry growth and the main advantages of this method include:

• Extremely high yields
• Optimal utilization of greenhouse area
• Maximum work convenience
• Relatively disease-free crops
• Relatively low costs
• Potential collection and recycling of drainage water

This growth method is gradually being established in commercial production areas. In 98/99 the scope of commercial produce area was 30,000 m2 and in the next growing season it will expand to 70,000 m2.

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