Agriculture Reference
In-Depth Information
Fig. 9.2
Table-top produc-
tion of everbearer strawberry
under Spanish multibay
tunnels in the UK
Cropping Systems
Producers throughout the world employ either short-day or
day-neutral cultivars. Short-day types initiate flowers in response to shortening day
length in autumn and have varying chilling requirements. High chill cultivars are
suited to temperate regions with long winters whereas the low chill types are suited
to areas with warmer winters where they will produce over an extended season.
Day-neutral cultivars initiate flowers irrespective of day length and temperature,
although flower and fruit development is optimum during longer days.
In most regions of production, growers will use cultivars of both types to extend
the season. In addition, a range of techniques are adopted either to advance or delay
the cropping period. Plants can be forced into early growth by raising temperatures
in the crop zone through the use of fleece/polythene film laid over the plants, low
polythene cloches, walk-in polythene tunnels or glasshouse structures with addi-
tional heat or light. In areas with cold winters, fruit production can be delayed by
the use of a deep layer of straw laid over the plants during cold conditions to trap
cold air around the plants and exclude light. The timing of production of short-day
plants can also be manipulated by cold storing either bare-root plants (frigoplants)
or tray-grown plants and planting them during a growth period (long days and high-
er temperatures). Depending on light and temperature, such plants will crop ap-
proximately 60 days later, permitting scheduled production (Lieten
2012
).
A high proportion of the strawberry crop is still produced in field soils but, in
some countries, an increasing proportion is grown in soilless substrates (usually
peat or coir based). The presence of soil-borne diseases can limit the availability of
'clean' soils and where few or no soil fumigants are approved for use, growers are
forced to grow out of soil to achieve the yields and fruit quality that are required
to maintain financial viability. Substrate production generally takes place in bags,
pots or troughs which are either laid on the ground (sometimes on soil ridges) or in-
creasingly on 'table-top' structures (Fig.
9.2
) where the fruit is produced at shoulder
height, helping to reduce picking costs.
When producing in field soils, it is common to plant on raised beds or ridges to
increase rooting depth, improve drainage and reduce soil-borne disease. Typically
