I U i-
Agricultural Research & Education .eiiue
VS University of Florida, IFAS
Dover AREC Rese ch Report DOV-1985-2 / hy, 1985
W TER USE IN STRAWBERRY TRANSPLANT STABLIS
E. E. Albregts and C. M. ..ward V /...
Water is u ed for. many purposes in the home, nj story a in agr culture,
Even though it eems to be plentiful, the amount ava t for agricult e has
limits since the supply is finite. Strawberry growers g povi e overhead '
sprinkler irriga ion to plants for moisture and use water as ^i the
application of p sticides. In addition, it is also used for cooin of plants
and as a source f energy (heat) for freeze protection. The cooling effect is
used quite exten ively in agriculture. Carolus (4) notes that it is used to
cool flower buds in orchards so as to delay opening of buds if freezes are still
likely, for cool ng crops to enhance yields, and to establish plants such as
strawberries, amcng other things.
Cooling pro esses: One might ask what processes are taking place for
cooling to occur th application of water. Cooling occurs because of: (1)
evaporation and ( ) the increase in temperature of the applied liquid, if the
liquid is cooler han the object to which it is applied. The least amount of
cooling occurs wi h the rise in temperature of water to the temperature of the
object to which i is applied. Only one calorie/g for each oC (9/50F) rise in
temperature is lo t from the surrounding environment. The largest amount of
cooling results f om evaporation.
When water e porates, i.e. changes from a liquid to a vapor, energy is
required. The ene gy required to evaporate water at 68oF is 590 calories/gram
(279,140 calories/ int) (5). The energy (heat) required to vaporize water must
come either from t e external surroundings or from the remaining liquid (5).
This can be illust ated by applying water, which is at body temperature, to
your body on a win y day and noticing the cooling effect on the body. This
implies that water does not need to be at the boiling point for evaporation to
occur. Evaporatio can take place at any temperature normally encountered on
the surface of the earth, even from frozen water, ice. Evaporation will
continue as long a the vapor pressure (moisture in the air) is less than the
saturated vapor pre sure (air holding as much water as possible at a
particular temperate e) (5). The rate of evaporation depends to a large
degree upon the dif erence between the saturated vapor pressure and the vapor
pressure of the air (5). Thus the lower the relative humidity (the ratio in
percent between the actual vapor pressure and the saturated vapor pressure) the
greater the rate of evaporation with all things being equal. In addition, wind
movement will incre se evaporation since wind will move the moist air from
around the area of evaporation and replace it with drier air. The drier air,
of course, reduces e relative humidity and increases evaporation.
Plant establish ent: As noted previously, strawberry growers employ
overhead sprinkler i rigation to establish transplants. Bare rooted strawberry
transplants set in b ack polyethylene mulched fruiting beds or in unmulched
nursery beds are est blished by overhead sprinkler irrigation operating for
about 8 hours daily or a period of 10 to 14 days (1). Irrigation is needed to
reduce the water str ss created by the damaged root system of the transplant,
which must form new oots to absorb water, the high surface temperature of the
mulch or bare soil, ite high ambient air temperature, and the usual dry
conditions normally sent at transplanting. With the current system, 4 to 20
inches of water are required to establish transplants depending on the condition
of the transplants and the weather. Without irrigation, the foliage of the
transplant dehydrates and becomes necrotic which results in considerable plant
mortality and delayed plant growth and development (1,2).
The purpose of the irrigation is to prevent the desiccation of the plant
foliage until the root system can develop and absorb sufficient moisture to
sustain the plant. The absorbed moisture not only provides water for life
sustaining processes but water is evaporated from the plant which helps to cool
it. Only a relatively small volume of water is required during the establishment
period. However, the irrigation system generally used by the grower is
designed to provide a large volume of water for moisture or freeze protection.
This results in excessive water use and leaching of fertilizer (3).
Water conservation: Because water is rapidly become a limiting resource,
every effort should be made to conserve its use. There are ways to reduce the
amount of water applied to establish and grow a strawberry nursery. With respect
to establishing the plants, one should determine if plants are from long term
cold storage or from local nurseries. Plants which have been stored for several
months in long term cold storage will have the foliage removed. Generally
sufficient starch is present in the roots of the transplant to establish
without leaves. The only leaves present are a couple of small leaves emerging
from the crown. Irrigation is provided to these plants only to keep the crowns
and the small emerging leaves cool and moist and for soil moisture. Thus,
irrigation for 15 minute intervals several times during the warm part of the
day is sufficient to cool these plants and maintain soil moisture.
Those plants without sufficient starch in their roots to support growth,
such as local plants, need more irrigation than plants from cold borage. 'These
plants need the leaves as a food source, either from stored reserves or from
that produced in photosynthesis. Thus, the leaves must be retained. These
plants are generally watered continuously during the warm part of the day from
transplanting to establishment. Consumption of water can be reduced with
intermittent irrigation (3). This method of irrigation involves the
application of water at intervals which meet the guidelines below. Control of
the intervals can be obtained with time clocks and solenoids or with other
devices. It may not be practical to adapt some irrigation systems for
intermittent irrigation. For those which can be adapted to intermittent
irrigation the following is a list of some of the practices required to
successfully establish plants. Items (1,2,3,4,9,10,12) apply for continuous
1. Set plants as soon as possible after digging from the nursery.
2. Do not allow plants to wilt from time of digging in the nursery until
irrigation is initiated after transplanting.
3. Use only healthy plants and remove dead leaves.
4. Turn irrigation on as soon as plants are set.
5. Thoroughly moisten transplants and mulch during the time the irrigation
cycle is "on". This usually takes at least 5 minutes of irrigation.
6. Resume the irrigation "on" cycle before the plants become dry.
7. Length of "on" cycle varies with climate; (a) hot, windy, and dry weather
results i longer "on" and shorter "off" cycles, (b) during cool and mofi.-
weather i ttle irrigation may be needed.
8. Plants sh uld not be permitted to wilt excessively during the "off" cycle .
9. Turn irri ation system "on" in the morning when plants begin to wilt.
10. Discontin e irrigation in the afternoon when it appears that plants will
not wilt xcessively for the remainder of the day.
11. If leaves start to become necrotic or difficult to moisten, then either
not enough water is being applied or the "off" cycle is too long.
12. The first ew days after plants are set in the field are more crucial
to establi hment than the period thereafter.
13. Response t intermittent irrigation varies with the variety used and the
condition f plants within a variety. Poor quality plants will require
more irrig tion and care.
Other meth ds growers can use to reduce water consumption to establish
strawberries n series are (1) reduce diesel engine speed, if allowed by
manufacturer, t reduce volume of water pumped and at the same time use smaller
size orfices (1 8") in sprinkler nozzles, and (2) pump from pits and recycle
water where pos ible.
After the lants are established reduced water consumption is still
possible. Irri ate during the night time hours when possible since
evaporation is ch less at night than during the day. Also pump from pits
and recycle water when possible. There probably are available other methods
to reduce cons tion in the nursery than those mentioned here. Those
discussed here 11 give you some ideas for methods you can use.
1. Albregts, E. E., and C. M. Howard. 1972. Influence of.defoliation at
transplanting on strawberry growth and fruiting response. HortScience 7.
2. Albregts, E. E., and C. M. Howard. 1982. Effect of transplant stress
on strawberry performance. HortScience 17:651-652.
3. .lbregts, E. E,, and"C.'M."Howard. 1985. Effect of intermittent sprinkler
irrigation on establishment of strawberry transplants. Proc. Fla. Soil
and Crops Sci. Soc. 44:(In Press).
4. Carolus, L. C. 1971. Evaporative cooling techniques for regulating
plant water stress. HortScience 6:23-25.
5. Semat, H. 1958. Fundmentals of physics. Rinehart & Co., Inc. NY,
NY. 914 -p.
The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
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