|  |
Water Use in Establishment of Young Blueberry Plants 1
Dorota Z. Haman, Allen G. Smajstrla, Robert T. Pritchard, Fedro S. Zazueta and Paul M. Lyrene2BLUEBERRY 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 ).
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.
Figure 3. Blueberry growth during three years of the experiment. 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. 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.
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.
Figure 4. Potential evapotransporation calculated from the Penman equation as compared to actual evapotranspiration of highbush and Rabbiteye blueberries. 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. 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. 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. 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. 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
This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.