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165
Comparison of Hydroponic Systems in the Strawberry Production
H. Ramírez-Gómeza, M. Sandoval-Villa, A. Carrillo-Salazar and A. Muratalla-Lúa
Colegio de Postgraduados, Campus Montecillo
Carretera México-Texcoco km 36.5, Montecillo, Texcoco 56230, State of Mexico
Mexico
Keywords: Fragaria × ananassa Duch., irradiance, temperature of the leaf and substrate,
SPAD readings, °Brix
Abstract
In Mexico strawberry is produced with high-technology, but there is little
research on the productivity of strawberry under hydroponic systems. The present
study was conducted to compare four hydroponic systems for the strawberry
production (Fragaria × ananassa Duch.): 1) single plastic bags, 2) vertical three-
levels (pipes), 3) vertical four-levels (pipes) and 4) vertical with hydroponic pots. The
experiment was carried out in a greenhouse tunnel type Colegio de Postgraduados,
Montecillo, State of Mexico. The objective was to assess what type of system the
strawberry plants develop better and reach higher yield and quality. To conduct the
experiment treatments were nested in an experimental design of blocks completely
at random with three replications. The upper levels of the systems were the most
active in photosynthetic irradiance (W/m2), leaf and substrate temperature and
highest percentage of °Brix. In yield, the vertical with hydroponic pots system
surpassed other systems, because it had the largest number of plants per unit area.
The vertical with four pipes system recorded the highest percentage of fruits of the
category corresponding to the large fruit and the vertical with three pipes was the
system which had the highest percentage of fruit of low quality.
INTRODUCTION
The strawberry (Fragaria × ananassa Duch.) is a strategic crop in Michoacan,
Mexico, and this crop generates a great number of jobs and foreign currency (Vázquez et
al., 2008). In the year 2009 Mexico recorded a harvested area of 6,678.20 ha, with a
production of 233,041.30 tons, by which reached an average efficiency of 34.9 t/ha
(SAGARPA, 2009). Higher economic, productive and higher quality fruits cultivars are
required in Mexico (Barrera and Sánchez, 2003).
Strawberry production is practiced currently in Mexico with high technology;
however, little has been explored regarding commercial hydroponics production systems
of high density (López et al., 2005). The vertical hydroponics system for crops of high
commercial value is practiced in USA, Japan, Australia and Italy (Al-Raisy et al., 2010),
as this contributes to a better use of energy and to a more efficient use of the spaces of the
greenhouses which results in higher yields per unit area (Paraskevopoulou et al., 1995).
Strawberry plants grown in such conditions reduces the water consumption, requires less
herbicides, the fruit obtained are cleaner and bigger; the yields are higher and it is
possible to gain earliness and improve the fruit quality (Yuan and Sun, 2004).
In Michoacan, Mexico, the strawberry is a crop that requires considerable labor
because of the delicacy of its processes (CONAFRESA, 2007). Farmers face significant
challenges, since consumers demand higher quality and it is necessary to comply with the
standards of quality, health and safety. So, it is necessary to find alternatives that allow
the cultivars to be more productive and to obtain higher quality, health and safe fruits.
The objective of this study was to compare four hydroponic systems for the strawberry
production and to determine in what conditions plants develop better, to get higher yield
and better quality.
a ramirez.humberto@colpos.mx
Proc. II IS on Soilless Culture and Hydroponics
Eds.: F.C. Gómez-Merino et al.
Acta Hort. 947, ISHS 2012
166
MATERIALS AND METHODS
The experiment was conducted in a greenhouse tunnel type located at Colegio de
Postgraduados, Montecillo, State of Mexico. This study was carried out at the beginning
of October 2010 until March 2011. A short photoperiod strawberry (Fragaria × ananassa
Duch.) ‘Camino Real’ was used. To provide the nutrient solution a drip irrigation system
was used. A red volcano scoria (diameter of particles less than 10 mm) was utilized as
substrate to support the plants. The universal Steiner’s nutrient solution (1984) at 50% of
its original concentration was used. The pH was adjusted weekly from 5.8 to 6.0 using
H2SO4. Four hydroponic strawberry production systems were assessed: individual bags
(BI), vertical with three PVC pipes of 6” diameter (V3P), vertical with four pipes (V4P),
and vertical with hydroponic pots (VHP) with 42, 90, 120 and 180 plants, respectively.
The treatments were accommodated in an experimental design of randomized blocks with
three replications. Leaf greenness index (or SPAD readings) was determined using a
SPAD-502. The first reading was held on 15 December 2010 and two more took place
later 30 and 60 days after the first. At each level of the column system, a plant was
randomly selected, and then a recently matured leaf was chosen and three readings per
treatment were taken. The photosynthetic incident irradiance (W/m) reached at the levels
of the systems, as well as on the outside of the greenhouse, was registered with a linear
radiometer LI-191SE (LI-COR). Leaf (Th) and substrate temperature (Ts), were recorded
with a telethermometer (ThermaTwin TN408LC) at each level of the systems. During the
nine cuts made in the harvest time, cumulative yield (g/plant) was quantified with an
analytical scale. The obtained results were classified by size whereas the equatorial
diameter (top of the fruit measured horizontally): >3.2, 2.6-3.1, 2.0-2.5 and 1.6-1.9 cm
corresponds to A, B, C and D sizes, respectively. Also, the fruit were classified by quality
grades (1st, 2nd and 3rd) according to the norm NMX-FF-062-SCFI-2002 for strawberry.
The °Brix was estimated with a portable ATAGON-1E refract_meter by squeezing a part
of the fruit. Juice drops were placed in the refract_meter for reading. The evaluated
variables were subjected to statistical analysis by an analysis of variance and comparison
of means (Tukey, P≤0. 05) with the Statistical Analysis System program (SAS, Institute,
2002; Cary, NC, USA).
RESULTS AND DISCUSSION
Incident Photosynthetic Irradiance, SPAD Readings and Leaf and Substrate
Temperature
The photosynthetic incident irradiance (PII) was significantly affected by the
treatments (Table 1). Inside the greenhouse the highest levels of the systems registered
the highest values of PII (Tukey, P≤0.05) (Table 2). The shade effect decreased the values
in all levels of the systems. According to the analysis of variance and the comparison of
means test (Tukey, P≤0.05) the leaves and substrate temperature (Table 1) showed
significant differences. The V3P system recorded the highest leaf temperature with
18.93°C (Table 2), followed by VM3 and V44 18.81 and 18.47°C, respectively. It was
observed that as the height of the level increased, plant leaf temperature was higher in all
systems. Also, the media temperature followed the same trend. V33 system again
recorded the highest temperature (19.52°C), higher than the leaf temperature. SPAD
readings were not affected by treatments or levels in any of the sampling: 75, 105 and 135
days after transplant (dat) (Table 1). In the first reading, plants were at the flowering
stage, and in the two subsequent readings, plants were in the fruiting stage.
Cumulative Yield
All the high density hydroponic systems evaluated were statistically different in
comparison to the individual bags (IB) system in cumulated yield (Tukey, P≤0.05)
(Table 3). Vertical hydroponic pot treatment (VMH) surpassed the other systems (Fig. 2)
with 4 595.30 g. The V4T system was the second that showed acceptable yield
(3,961.40 g) followed by the V3T system (2,755.30 g), while the IB system showed
167
minimal yield of all (856.00 g).
°Brix
°Brix of the harvested fruits was higher (Tukey, P≤0.05) in the highest levels of
each hydroponic system (Table 3). The comparison of means test (Tukey, P≤0.05) formed
eight groups. V42, V43, and V44 systems were the highest with an average of 9.73, 9.85
and 9.94% of °Brix (Fig. 3). The V33 system reached the second position with an average
of 10.63% and the VMH5 system was the best of all, since the submission of the highest
value of °Brix with an average of 10.85%. Wang and Camp (2000) mentioned that the
content of soluble sugars is affected by the maturation state, genotype, the geographical
origin and the growth temperature. All levels of systems exceed the index of quality of
°Brix according to Mitcham et al. (2002) with a minimum soluble solids content of
7°Brix.
Size
With regard to the fruits size (significant Tukey, P≤0.05) difference was only
found in categories A and D for the levels of hydroponic systems (Table 3). The
comparison of means test formed four statistical groups in the A category (Table 4). The
VMH3 system was placed in the second position with 48.70% of fruits of category A,
about half of the harvested fruits of this system presented fruits of large size. The system
V41 recorded 57.49% of fruits of the A category corresponding to the large fruit (>3.2 cm
in diameter), beating everyone. About 60% of the harvested fruits were of this category.
The comparison of means test (Tukey, P≤0.05) formed three groups within the category
D (1.6-1.9 cm in diameter). The V33 system recorded the 24.05% of fruits in this
category, and it was the only in the group A that had the highest percentage of small
fruits. The top systems level recorded the highest percentage of fruits of the category D.
Quality Grades
There were found significant differences in the first and third class in the
percentage of the fruits quality (Table 3). The V41 system was the best of all within the
group a with 51.79% of corresponding to the first fruit quality (Table 5). In the 3rd quality
corresponding to fruits of low quality (defects in fruit such as scrapes, sunburn, bruises
and that should not exceed 10% of the total surface of the fruit) there were significant
differences (Tukey, P≤0.05). The V33 system got the highest percentage of fruits of low
quality: 51.90%. The upper levels of the systems were those that recorded the highest
percentage of 3rd quality fruits, this because of the pest Tetranychus urticae Koch.
Klamkowski et al. (2007) mentioned that this species when feeding on the sap of the plant
reduces its vigor, quality and yield.
CONCLUSIONS
A greater number of strawberry plants per unit area increased yield. These results
were similar to results reported by Pérez et al. (2005) who showed that the yield per unit
of area was reached with the highest densities.
As the height, in a system, increases; photosynthetic incident irradiance, and
temperature of leaves and substrate increases.
Levels of the vertical system with four pipes reached a higher percentage of fruits
of category A, as well as levels of quality (first) and it was the second system which
showed higher yield per unit area.
ACKNOWLEDGEMENTS
Our gratitude to Colegio de Postgraduados for funding this research.
Literature Cited
Al-Raysi, F.S., Al-Said, F.A., Al-Rawahi, M.S., Khan, I.A., Al-Makhamari, S.M. and
Khan, M.M. 2010. Effects of column sizes and media on yield and fruit quality of
168
strawberry under hydroponic vertical system. European J. Sci. Res. 43:48-60.
Barrera, C.G. and Sánchez, B.C. 2003. Caracterización de la cadena
agroalimentaria/agroindustrial nacional, identificación de sus demandas tecnológicas:
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de Camacaro, M.P., Carew, J. and Battey, N. 2005. Efecto de la densidad de plantación
sobre el crecimiento vegetativo y reproductivo de la fresa cv. Elsanta. Bioagro 17:11-
15.
Consejo Nacional de la Fresa. 2011. www.conafresa.com.
Klamkowski, K., Sekrecka, M., Fonyodi, H. and Treder, W. 2007. Changes in the rate of
gas exchange, water consumption and growth in strawberry plants infested with the
two-spotted spider mite. J. Fruit Ornam. Plant Res. 15:155-162.
López, P.L., Cárdenas, N.R., Lobit, P., Martínez, C.O. and Escalante, L.O. 2005.
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Mex. 28:171-174.
NMX-FF-062-SCFI. 2002. Norma mexicana para productos alimenticios no
industrializados para consumo - humano - fruta fresca - fresa (Fragaria × ananassa.
Dutch) - Especificaciones y Método de Prueba. Secretaría de Economía, México, DF.
Paraskevopoulou, P.G., Grafiadellis, M. and Paresis, E. 1995. Productivity, plant
production and fruit quality of strawberry plants grown in soil and soilless culture.
Acta Hort. 408:109-117.
Secretaria de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación. 2011.
www.sagarpa.gob.mx.
Steiner, A.A. 1984. The universal nutrient solution. Proc. Sixth International Congress on
Soilless Culture. ISOSC. Lunteren, Wageningen, The Netherlands. p.633-649.
Vázquez, G., Cárdenas, R. and Lobit, P. 2008. Efecto del nitrógeno sobre el crecimiento y
rendimiento de fresa regada por goteo y gravedad. Agric. Tec. Mex. 2:235-241.
Wang, S. and Camp, M. 2000. Temperatures after bloom affect plant growth and fruit
quality of strawberry. J. Hort. Sci. 85:183-199.
Wang, S. and Lin, H.S. 2000. Antioxidant activity in fruits and leaves of blackberry,
raspberry, and strawberry varies with cultivar and development. J. Agri. Food Chem.
48:140-146.
Yuan, B.Z. and Sun, S.N. 2004. Effect of drip irrigation on strawberry growth and yield
inside a plastic greenhouse. Biosyst. Engin. 87:237-245.
Tables
Table 1. Statistical significance (Pr > F) hydroponic systems on photosynthetic incident
irradiance, leaves and media temperature and SPAD readings.
SV DF PII Temperature SPAD readings
Leaf Substrate 75 dat 105 dat 135 dat
B 2 0.0875 0.9484 0.8178 0.5435 0.3803 0.3471
Trt 3 <.0001 <.0001 <.0001 0.9381 0.0757 0.9969
E 6
T 11
SV: Sources of variation; DF: degrees of freedom; B: blocks; Trt: treatments; E: error; T: total.
PII: photosynthetic incident irradiance.
dat: days after transplant.
169
Table 2. Grouping of means by the Tukey method (P≤0. 05) of the leaves and media
temperature and photosynthetic incident irradiance (PII) of hydroponic systems for
strawberry production.
LIHS Th (°C) Ts (°C) PII (W/m)
V33 18.93 a 19.52 a 128.67 b
VM3 18.81 ab 18.85 ab 117.77 b
V44 18.47 ab 17.03 abc 117.00 b
V32 16.41 abc 15.88 abc 75.47 c
BI 16.07 abc 15.85 abc 117.10 b
V43 15.58 abcd 15.80 abc 80.40 c
V42 15.48 abcd 14.82 bcd 70.23 c
VM2 14.86 bcd 14.27 cd 80.40 c
V31 14.42 cd 12.97 cd 71.67 c
V41 13.73 cd 12.80 cd 68.03 c
VM1 12.07 d 10.88 d 70.07 c
Exterior 282.67 a
Means with different letters are statistically different (Tukey, P≤0.05).
LIHS: level inside the hydroponic systems; Th: leaf temperature; Ts: substrate temperature.
Table 3. Statistical significance (Pr>F) of hydroponic systems on the cumulative yield,
quality and size of strawberry fruits.
SV DF CY °Brix Quality grades Size
1s
t
2
n
d
3
r
d
A B C D
B 2 0.2543 0.0286 0.8943 0.0737 0.0687 0.0086 0.1147 0.0161 0.2480
Trt 3 <0.0004 <.0001 0.0095 0.4158 0.0092 0.0026 0.0349 0.0765 0.0043
E 6
T 11
SV: Sources of variation; df: degrees of freedom; B: blocks; Trt: treatments; E: error; T: total.
CY: cumulative yield.
170
Table 4. Grouping of means by the method of Tukey (P ≤ 0. 05) of the percentage of the
size of fruit in every level of hydroponic systems for strawberry production.
LIHS
Size
A Tukey
P≤0.05 B Tukey
P≤0.05 C Tukey
P≤0.05 D Tukey
P≤0.05
BI 30.52 abc 20.55 ns 39.49 ns 9.45 ab
V31 40.08 abc 36.51 ns 20.05 ns 3.35 b
V32 41.41 abc 26.07 ns 23.83 ns 8.68 ab
V33 19.15 bc 24.71 ns 32.09 ns 24.05 a
V41 57.50 a 26.30 ns 15.09 ns 1.11 b
V42 40.76 abc 38.88 ns 15.91 ns 4.44 b
V43 46.15 abc 33.35 ns 16.84 ns 3.66 b
V44 27.89 abc 24.23 ns 37.10 ns 10.78 ab
VMH1 16.83 c 42.70 ns 34.06 ns 6.41 b
VMH2 35.96 abc 29.13 ns 32.72 ns 2.19 b
VMH3 48.70 ab 34.80 ns 13.90 ns 2.60 b
VMH4 25.25 bc 43.31 ns 29.20 ns 2.24 b
VMH5 35.92 abc 33.78 ns 21.61 ns 8.68 ab
Means with different letters are statistically different (Tukey, P≤0.05).
LIHS: level inside the hydroponic systems; ns: not significant.
Table 5. Grouping of means by the method of Tukey (P≤0. 05) of the percentage of the
fruit quality in every level of hydroponic systems for strawberry production.
LIHS
Quality
1st Tukey
P≤0.05 2nd Tukey
P≤0.05 3rd Tukey
P≤0.05
BI 37.17 Abc 39.85 Ns 22.97 b
V31 37.72 Abc 37.72 Ns 24.56 ab
V32 37.96 Abc 34.26 Ns 27.78 ab
V33 20.63 C 27.46 Ns 51.90 a
V41 51.79 A 27.21 Ns 21.00 b
V42 40.00 Abc 44.17 Ns 15.83 b
V43 47.70 Ab 31.24 Ns 21.06 b
V44 32.05 Abc 26.93 Ns 41.03 ab
VMH1 26.55 Bc 39.25 Ns 34.20 ab
VMH2 39.83 Abc 40.87 Ns 19.30 b
VMH3 36.21 Abc 35.36 Ns 28.43 ab
VMH4 29.70 abc 41.62 Ns 28.68 ab
VMH5 36.61 abc 33.89 Ns 29.50 ab
Means with different letters are statistically different (Tukey, P≤0.05).
LIHS: level inside the hydroponic systems
ns: not significant.
171
Figures
Fig. 1. Hydroponic systems. (a) individual bags; (b) vertical with three pipes; (c) vertical
with four pipes; and (d) vertical with hydroponic pots.
Fig. 2. Cumulative yield of hydroponic systems for strawberry production. Means with
different letters are statistically different (Tukey P≤0. 05). BI: individual bags;
V3T: vertical with three pipes; V4T: vertical with four pipes; VMH: vertical with
hydroponic pots.
c
856.00
b
2 755.30
ab
3 961.40
a
4 595.30
0,00
500,00
1000,00
1500,00
2000,00
2500,00
3000,00
3500,00
4000,00
4500,00
5000,00
BI V3T V4T VMH
Cumulative yield (g/plant)
Hydroponical Systems
172
Fig. 3. °Brix at each level inside of hydroponic systems for strawberry production. Means
with different letters are statistically different (Tukey, P≤0.05). Abbreviations: BI:
individual bags; V31: vertical with three pipes, level one; V32: vertical with three
levels, two pipes; V33: vertical with three pipes, level three; V41: vertical with
four pipes, level one; V42: vertical with four pipes, level two; V43: vertical with
four pipes, level three; V44: vertical with four pipes, level four; VMH1: vertical
with hydroponic pots, level one; VMH2: vertical with hydroponic pots, level two;
VMH3: vertical with hydroponic pots, level three; VMH4: vertical with
hydroponic pots, level four; VMH5: vertical with hydroponic pots, level five.
VM1, VM2, and VM3 are low, medium and high levels in hydroponic pots,
respectively.
cde
8.92
cde
8.89
bcd
9.49
ab
10.63
de
8.42
abc
9.73
abc
9.85
abc
9.94
e
7.96
cde
8.89
cd
9.34
bcd
9.53
a
10.85
0,00
2,00
4,00
6,00
8,00
10,00
12,00
BI
V31
V32
V33
V41
V42
V43
V44
VMH1
VMH2
VMH3
VMH4
VMH5
°Brix(%)
Level inside the hydroponical system