Water Use in Establishment of Young Blueberry Plants
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Water Use in Establishment of Young Blueberry Plants

   

Water Use in Establishment of Young Blueberry Plants 1

Dorota Z. Haman, Allen G. Smajstrla, Robert T. Pritchard, Fedro S. Zazueta and Paul M. Lyrene2

BLUEBERRY PRODUCTION IN FLORIDA

Blueberries show great promise as a Florida fruit crop. Although blueberries are grown in many other states, Florida's climate allows fruit to reach maturity earlier, avoiding competition with growers in other states, thus commanding high prices. This advantage has been increased by the recent introduction of earlier-yielding highbush varieties.

Currently, about 2,100 acres of blueberries are grown in Florida. This acreage is expected to expand as more growers take advantage of Florida's unique market window and new early-yielding blueberry varieties, and as existing growers expand their acreage. Presently, the blueberry acreage is evenly divided between rabbiteye and highbush varieties. However, for the last 10 years, new plantations have been almost exclusively planted to highbush varieties.

Newly developed early ripening highbush varieties are of the greatest interest to Florida growers at this time. These varieties are lower yielding and much more difficult to grow than rabbiteye varieties, but the early ripening fruit brings high prices since it is the only blueberry available at this time. Before May 20, the average price is very high per pound. After June 1, the average price drops to around one dollar per pound. Highbush plants are more difficult to establish and have a shorter life expectancy than the rabbiteye varieties. They are also much more sensitive to water stress and they require frequent irrigation to grow and produce even when well established.

Rabbiteye blueberries are native to Florida. These are relatively easy to grow and are considered the highest yielding type of blueberry for north Florida. The plants are more vigorous, longer living, higher yielding, and later ripening than the highbush variety. However, the rabbiteyes experience some problems with fruit setting due to pollination problems, thus yields do not always reach the expected levels. If pollination problems can be solved, it is very likely that rabbiteyes will again account for a significant percentage of new plantings since they are much easier to grow, and once established, live longer and have higher potential yields. During the establishment period the plants respond very well to irrigation; however, once well established, they are relatively insensitive to drought. In addition, rabbiteye blueberries can be mechanically harvested which results in a significant decrease in production cost.

BLUEBERRY IRRIGATION

The importance of irrigating young blueberry plants has been recognized for some time. In dry years, irrigation is very important during fruit formation. Berry size can be significantly increased in a dry year if irrigation is used to maintain moist soil conditions in the plant root zone. Sufficient moisture is not only critical during fruit production but is also important for the future of the plants since adequate irrigation during bud formation is critical for next year's crop (Lyrene and Crocker, 1991). Irrigation is critical to successful production in Florida because rainfall is typically low during the time of blueberry bud formation.

Blueberries are often grown using organic mulches such as pine bark. The mulch provides protection against high temperatures, decreases evaporation from the soil, and with time, provides organic material to the soil. Organic mulches may also help reduce soil pH which is beneficial to the blueberry plant. Earlier research at the University of Florida demonstrated the importance of an organic mulch ground cover and precise irrigation scheduling on the growth of young rabbiteye and highbush blueberry plants (Haman et al., 1988).

The recommendations presented in this publication were developed based on a three year experiment on water requirements for establishment of young blueberry plants which was conducted at the University of Florida. The project was partially funded by the St. Johns River and the Southwest Florida Water Management Districts. Both native rabbiteye and newly developed early-yielding highbush varieties were studied. Two-year old, container-grown plants were transplanted to the field at the beginning of 1991. The experiment ended in December 1993. Total water use (evapotranspiration) of the plants, irrigation requirements, crop yield, and vegetative plant growth were evaluated for the three years after transplanting. Three different threshold levels of soil water tension were evaluated for scheduling irrigations. The threshold soil tension were set at 10 centibars (cb), 15 cb, and 20 cb.

In Florida, blueberries are usually grown on sandy soils with low water holding capacities and large pore spaces. Thus, water applications must be frequent and relatively small to avoid water losses from the root zone. This requires precise irrigation scheduling. Microirrigation, which was used in the experiment on establishment of blueberry plants, applies water directly to the crop root zone. The amount and placement of water can be precisely controlled with this system to minimize application losses. The microirrigation system was controlled using magnetic switching tensiometers (Smajstrla et al., 1988).

With the microirrigation system used in this study, water was not applied to the grass alleyways between plant rows. Also, organic pine bark mulch minimized evaporation losses from the soil surface. Irrigation requirements would need to be adjusted for other plant sizes, irrigation systems and/or production practices. For example, a greater volume of water would be required with a sprinkler irrigation system because water would be applied to the entire soil surface rather than being limited to the mulched area near each plant.

Figure 1 and Figure 2 present the cumulative irrigation for both varieties of blueberry during three years of the experiment. The significant increase in the slope of the lines during the last year of the experiment for all treatments (with exception of 20-cb highbush) reflects the higher water requirement of the larger plants and the lower rain contribution during that year.

Figure 1. Cumulative irrigation over three years of the experiment for Rabbiteye blueberries.

Figure 2. Cumulative irrigation over three years of the experiment for Highbush blueberries.

YOUNG BLUEBERRY WATER USE

Water use in gal/acre and inches/acre for the first three years after transplanting for both varieties of blueberries is presented in Table 1 , Table 2 , Table 3 , Table 4 , Table 5 , Table 6 . The numbers were developed for different plant densities depending on the field spacing between the plants. These quantities are relatively small because they are specific for the young, small, microirrigated blueberry plants studied in this research. The portion of the water demand which must be supplied by irrigation depends on system efficiency and rainfall effectiveness and can be calculated using the water budget method.

RESPONSE OF YOUNG BLUEBERRY PLANTS TO IRRIGATION

Growth of blueberry plants was measured monthly. The volume of each plant canopy was calculated from three measurements: the height, the width along the plant row, and the width perpendicular to the row.

Plant volumes increased each year for all treatments. Both plant size and rate of increase were greater for rabbiteye plants as compared to highbush plants. Among highbush plants only the 10-cb treatment showed significant growth, most of which occurred in the last year of the experiment. During 1993, the 10-cb plants grew almost 2 ft, while the 15-cb and 20-cb highbush plants showed very little increase in height in all three years due to water stress and poor establishment of the root system. Overall, the 10-cb treatment had the highest growth rate for both varieties. In 1993, the rate of growth for the 15-cb and 20-cb treatments was very small and significantly lower than the 10-cb treatment ( Figure 3 ).

Figure 3. Blueberry growth during three years of the experiment.
Rabbiteye plant heights increased mainly in the first year after transplanting (1991), especially in the 10-cb treatment. During that year, the 10-cb plants reached approximately 5 ft. The 15-cb and 20-cb treatments were slightly shorter and reached 5 ft at the end of the second year. By the end of 1993, the 10-cb rabbiteye treatment plants were approximately 6 ft tall with 15-cb slightly shorter at 5.6 ft and 20 cb at 5.3 ft.

In 1991, following common practice for young plants to stimulate vegetative growth, the flowers were removed from the plants, preventing fruit from setting. This is reflected in the 1991 plant growth pattern. Most of the plants showed an increase in volume in all months until September. In 1992 and 1993, most of the increase in plant size occurred during the three months after fruit harvest. Little change in plant size occurred during the spring months as fruit was set and grew to maturity.

Fruit production data were collected during the last two years of the research and are presented in Table 5 . The two types of rabbiteye plants yielded differently and for this reason are presented separately.

Table 5.

Table 5. Blueberry yield in lbs/acre* as a function of the three irrigation levels during first two years of fruiting.


Year


Irrigation Treatment


Rabbiteye Powderblue


Rabbiteye Premier


Highbush


1992


10 cb

7,760

3,680

3,080


15 cb

6,250

3,450

1,060


20 cb

8,310

3,360

520

1993


10 cb

5,590

4,690

2,200


15 cb

5,260

4,430

2,040


20 cb

5,890

3,710

820

* Yield calculated based on plant density of 1000 plants /acre


The fruit for all three cultivars matured at different times of the year, and yields varied as a function of time of harvest. In both years, yields were lowest for the early-producing Sharpblue (highbush) variety, largest for the late-producing Powderblue (rabbiteye) variety, and intermediate for the midseason rabbiteye variety, Premier. This is important since timing of harvest is critical to blueberry growers. Early-producing varieties are in great demand because early yields command much higher market prices.

Sensitivity to water stress was greatest in the highbush variety. Both vegetative growth and yield were strongly dependent on irrigation. Only the well-watered (10 cb) treatment was well established and healthy at the end of three years. The plants in this treatment were much larger and produced significantly more berries. All rabbiteye plants were well established by the end of three years and there were only small differences between the water treatments.

Figure 4 shows the annual distributions of monthly ET for the well-watered rabbiteye and highbush plants as a function of time during the first three years after transplanting. The ET pattern is consistent with the patterns of climate demand as measured by Penman ETo (reference evapotranspiration). In 1991 the peak monthly ET occurred in June. For all three years, the peak monthly ET for both varieties occurred in July. This closely follows the peak climate demand, and it is largely a result of levels of solar radiation and temperatures.

Figure 4. Potential evapotransporation calculated from the Penman equation as compared to actual evapotranspiration of highbush and Rabbiteye blueberries.
Evapotranspirational (ET) rates were larger for the rabbiteye plants as compared to the highbush plants. This difference was due to plant size and growth characteristics. The rabbiteye plants are more vigorous and rapidly-growing than the highbush plants.

CONCLUSIONS AND RECOMMENDATIONS

The establishment and water requirements of plants are strongly dependent on the blueberry variety. Two typical types of blueberry plants were evaluated in this experiment: rabbiteye, which is native to Florida, and highbush, which is an introduced variety. Growers are very interested in highbush plants due to their early ripening and the high prices which blueberries bring early in the year.

The rabbiteye variety is easier to establish and easier to grow successfully under Florida conditions. Plants grow rapidly after transplanting, and were relatively insensitive to imposed water stresses up to 20 cb. As compared to highbush plants, rabbiteyes have a deeper root system which allows them to uptake water from a larger volume of soil, resulting in more efficient irrigation scheduling and fewer losses to deep percolation. At the end of the third year of this project, the establishment of rabbiteye blueberries was good under all treatments. There was only small visible difference among plants.

As compared to rabbiteye, the highbush variety is much more difficult to establish and requires more precise water management. Plants exhibit high sensitivity to water stress and require frequent irrigation for good establishment. It takes longer for highbush plants to develop a root system. Most of the roots in this variety are located relatively close to the soil surface, which makes efficient irrigation scheduling more difficult. As a result, more water is lost to deep percolation.

Well-watered highbush plants (10-cb treatment) were very well established at the end of the experiment. However, two drier treatments showed much less vegetative growth and much lower yields than the well-watered plants. It can be concluded that the establishment of highbush blueberries under Florida conditions will not be successful without irrigation, and that irrigations should be scheduled at 10 cb.

REFERENCES

Haman D.Z., A.G. Smajstrla and P.M. Lyrene. 1988. Blueberry response to irrigation and ground cover. Proc. Fla. State Hort. Soc. 101:235-238.

Lyrene, P.M. and T.E. Crocker. 1986. Florida blueberry handbook. Circular 564. Univ. of Fla. Coop. Ext. Ser., Gainesville, FL. 15 pg.

Lyrene P.M. and T.E. Crocker. 1991. Commercial blueberry production in Florida. SS-FRC-002. Univ. of Fla. Coop. Ext. Ser., Gainesville, FL. 49

Smajstrla A.G., D.Z. Haman and P.M. Lyrene. 1988. Use of tensiometers for blueberry irrigation scheduling. Proc. Fla. State Hort. Soc. 101:232-235.

Tables

Table 1.

Table 1. Water use in inches per acre per month as a function of density for rabbiteye blueberries.




Density (plants/acre)




600


700


800


900


1000


1100


1200


Year 1


APR


0.2


0.3


0.3


0.3


0.4


0.4


0.4



MAY


1.0


1.2


1.3


1.5


1.7


1.8


2.0



JUN


1.4


1.6


1.8


2.1


2.3


2.5


2.8



JUL


1.5


1.7


1.9


2.2


2.4


2.7


2.9



AUG


1.4


1.6


1.9


2.1


2.3


2.6


2.8



SEP


1.3


1.5


1.7


1.9


2.2


2.4


2.6



OCT


1.1


1.3


1.5


1.6


1.8


2.0


2.2



NOV


0.7


0.8


0.9


1.1


1.2


1.3


1.4



DEC


0.3


0.4


0.4


0.5


0.5


0.6


0.6


Year 2


JAN


0.3


0.4


0.4


0.5


0.5


0.6


0.6



FEB


0.3


0.4


0.4


0.5


0.6


0.6


0.7



MAR


0.5


0.6


0.7


0.8


0.9


1.0


1.1



APR


1.1


1.3


1.5


1.7


1.9


2.1


2.3



MAY


1.3


1.9


2.1


2.4


2.6


2.9


3.2



JUN


1.6


1.9


2.2


2.4


2.7


3.0


3.2



JUL


2.0


2.2


2.5


2.9


3.2


3.5


3.8



AUG


1.9


1.7


2.0


2.2


2.5


2.7


3.0



SEP


1.2


1.3


1.5


1.7


1.9


2.1


2.3



OCT


0.9


1.1


1.2


1.4


1.5


1.7


1.8



NOV


0.6


0.6


0.7


0.8


0.9


1.0


1.1



DEC


0.3


0.4


0.5


0.5


0.6


0.6


0.7


Year 3


JAN


0.3


0.4


0.5


0.5


0.6


0.6


0.7



FEB


0.3


0.3


0.3


0.4


0.4


0.5


0.5



MAR


0.4


0.4


0.5


0.5


0.6


0.6


0.7



APR


1.2


1.4


1.7


1.9


2.1


2.3


2.5



MAY


2.6


3.0


3.4


3.9


4.3


4.7


5.2



JUN


2.9


3.4


3.9


4.3


4.8


5.3


5.8



JUL


3.2


3.7


4.2


4.7


5.3


5.8


6.3



AUG


3.1


3.6


4.1


4.6


5.1


5.6


6.1



SEP


2.6


3.0


3.5


3.9


4.3


4.8


5.2



OCT


1.2


1.4


1.5


1.7


1.9


2.1


2.3



NOV


0.6


0.7


0.9


1.0


1.1


1.2


1.3



DEC


0.6


0.7


0.8


0.9


1.1


1.2


1.3


Data not available for first 3 months of the first year.


Table 2.

Table 2. Water use in inches per acre per month as a function of density for highbush blueberries.




Density (plants/acre)




600


700


800


900


1000


1100


1200


Year 1


APR


0.3


0.4


0.4


0.5


0.5


0.6


0.6



MAY


0.3


0.4


0.4


0.5


0.6


0.6


0.7



JUN


0.7


0.9


1.0


1.1


1.2


1.4


1.5



JUL


0.7


0.9


1.0


1.1


1.2


1.4


1.5



AUG


0.7


0.8


1.0


1.1


1.2


1.3


1.4



SEP


0.6


0.8


0.9


1.0


1.1


1.2


1.3



OCT


0.5


0.6


0.7


0.8


0.9


0.9


1.0



NOV


0.5


0.5


0.6


0.7


0.8


0.8


0.9



DEC


0.3


0.4


0.4


0.5


0.5


0.6


0.6


Year 2


JAN


0.4


0.4


0.5


0.6


0.6


0.7


0.7



FEB


0.4


0.4


0.5


0.5


0.6


0.7


0.7



MAR


0.4


0.5


0.6


0.6


0.7


0.8


0.8



APR


0.5


0.6


0.7


0.8


0.8


0.9


1.0



MAY


0.7


0.8


0.9


1.0


1.1


1.2


1.4



JUN


0.9


1.0


1.1


1.3


1.4


1.6


1.7



JUL


1.1


1.3


1.5


1.7


1.9


2.1


2.9



AUG


1.1


1.3


1.5


1.7


1.9


2.1


2.2



SEP


1.0


1.1


1.3


1.5


1.6


1.8


1.9



OCT


0.8


1.0


1.1


1.3


1.4


1.5


1.7



NOV


0.5


0.6


0.7


0.8


0.9


1.0


1.0



DEC


0.3


0.4


0.4


0.5


0.5


0.6


0.6


Year 3


JAN


0.2


0.2


0.2


0.2


0.2


0.3


0.3



FEB


0.2


0.2


0.3


0.3


0.3


0.4


0.4



MAR


0.3


0.4


0.4


0.5


0.6


06


0.7



APR


1.0


1.2


1.4


1.6


1.7


1.9


2.1



MAY


1.8


2.1


2.4


2.7


3.0


3.3


3.6



JUN


2.0


2.4


2.7


3.0


3.4


3.7


4.0



JUL


2.3


2.7


3.1


3.4


3.8


4.2


4.6



AUG


2.1


2.5


2.9


3.2


3.6


3.9


4.3



SEP


2.0


2.3


2.6


3.0


3.3


3.6


3.9



OCT


1.2


1.4


1.6


1.8


2.0


2.2


2.4



NOV


1.0


1.2


1.3


1.5


1.7


1.8


2.0



DEC


1.0


1.2


1.4


1.5


1.7


1.9


2.0


Data not available for first 3 months of the first year.


Table 3.

Table 3. Water use in gallons per acre per month as a function of density for rabbiteye blueberries.


Density (plants/acre)




600


700


800


900


1000


1100


1200


Year 1


APR


5922


6908


7895


8882


9869


10856


11843



MAY


27239


31779


36379


40859


45398


49938


54478



JUN


37813


43485


49697


55909


62121


68333


74546



JUL


39312


45865


52417


58969


65521


72073


78625



AUG


37865


44176


50487


56797


63108


69419


75730



SEP


35003


40837


46671


52504


58338


64172


70006



OCT


29641


34581


39521


44461


49401


54341


59281



NOV


18916


22069


25221


28974


31527


34679


37832



DEC


8323


9710


11097


12485


13872


15259


16646


Year 2


JAN


8656


10098


11541


12984


14426


15869


17312



FEB


8948


10439


11931


13422


14913


16405


17896



MAR


14745


17202


19660


22117


24575


27032


29490



APR


30506


35590


40674


45759


50843


55927


61012



MAY


42961


50121


57281


64441


71601


78762


85922



JUN


43766


51060


58355


65649


72343


80238


87532



JUL


51808


60443


69078


77712


86347


94982


103616



AUG


40051


46726


53401


60076


66751


73426


80101



SEP


31096


36279


41462


46645


51827


57010


62193



OCT


24492


28574


32656


36738


40820


44902


48984



NOV


14875


17354


19833


22312


24791


27271


29750



DEC


9321


10874


12427


13981


15534


17088


18641


Year 3


JAN


9352


10910


12469


14028


15586


17145


18703



FEB


6703


7820


8937


10054


11172


12289


13406



MAR


9510


11095


12680


14265


15850


17435


19020



APR


33537


39781


44717


50306


55896


61485


67075



MAY


70134


81823


93511


105200


116889


128578


140267



JUN


78356


91415


104475


117534


130593


143653


156712



JUL


85603


99870


114137


128404


142671


156938


171205



AUG


82793


96592


110391


124190


137989


151788


165587



SEP


70762


82556


94350


106144


117937


129731


141525



OCT


31450


36691


41933


47175


52416


57658


62899



NOV


17235


20108


22981


25853


28726


31598


34471



DEC


170069


19914


22789


25604


28449


31294


34138


Data not available for first 3 months of the first year.

Table 4.

Table 4. Water use in gallons per acre per month as a function of density for highbush blueberries.


Density (plants/acre)




600


700


800


900


1000


1100


1200


Year 1


APR


8356


9749


11141


12534


13927


15319


16712



MAY


8882


10363


11843


13323


14804


16284


17765



JUN


20035


23374


26713


30052


33391


36730


40069



JUL


20166


23527


26888


30249


33610


36971


40332



AUG


19245


22453


25660


28868


32075


35283


38490



SEP


17436


20342


23248


26153


29059


31965


34871



OCT


13949


16273


18598


20923


23248


25572


27897



NOV


12337


14393


16449


18505


20561


22617


24673



DEC


8422


9825


11229


12633


14036


15440


16843


Year 2


JAN


9915


11567


13219


14872


16524


18177


19829



FEB


9558


11151


12744


14337


15930


17523


19116



MAR


11404


13305


15205


17106


19007


20907


22808



APR


13665


15942


18220


20497


22775


25052


27330



MAY


18378


21441


24504


27566


30629


33692


36755



JUN


23137


26993


30849


34105


38561


42417


46274



JUL


30995


36161


41327


46493


51659


56825


61991



AUG


30421


35491


40561


45631


50701


55772


60842



SEP


26334


30723


35112


39502


43891


48280


52669



OCT


22740


26530


30320


34110


37900


41690


45480



NOV


14171


16532


18894


21256


23618


25979


28341



DEC


8533


9956


11378


12800


14222


15645


17067


Year 3


JAN


3988


4652


5317


5981


6646


7311


7915



FEB


5134


5990


6846


7701


8557


9413


10268



MAR


8994


10493


11992


13491


14990


16489


17987



APR


27982


32645


37309


41973


46636


51300


55964



MAY


49032


57204


65976


73548


81720


89892


98064



JUN


54793


63925


73057


82189


91321


100453


109585



JUL


62157


18516


82876


93235


103595


113954


124314



AUG


58228


67933


77638


87343


97047


106752


116457



SEP


53355


62247


71140


80032


88925


97817


106710



OCT


32057


37400


42743


48085


53428


58771


64114



NOV


27255


31798


36340


40883


45425


49968


54510



DEC


27722


32343


36963


41584


46204


50824


55445


Data not available for first 3 months of the first year.

Table 6.

Table 6. Water use per plant in gallons during first three years of blueberry establishment.

Year 1

Year 2

Year 3

Month


HB*


RE*


HB


RE


HB


RE


Jan


-


-


17


14


7


16


Feb


-


-


16


15


9


11


Mar


-


-


19


15


15


16


Apr


14


10


23


51


47


56


May


15


45


31


72


82


117


Jun


33


62


39


72


91


131


Jul


34


66


52


86


104


143


Aug


32


63


51


67


97


138


Sept


29


58


44


52


89


118


Oct


23


49


38


41


53


52


Nov


20


32


24


25


46


29


Dec


14


14


14


16


46


28


*HB-highbush RE-rabbiteye


Footnotes

1. This document is BUL296, one of a series of the Agricultural and Biological Engineering Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date August 1994. Reviewed December 2005. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.

2. Dorota Z. Haman, Associate professor; Allen G. Smajstrla, Professor; Robert T. Pritchard, Graduate Research Assistant; Fedro S. Zaueta, professor, Agricultural and Biological Engineering Department; and Paul M. Lyrene, Professor, Horticultural Science Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.



Copyright Information

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