Donald Bailey, Rhuanito Soranz Ferrarezi, Seti Balkaran and Jomanni Bernier
University of the Virgin Islands, Agricultural Experiment Station, Horticulture and
Aquaculture
program, RR#1 Box 10,000, Kingshill, VI 00850. E-mail address: rhuanito.ferrarezi@uvi.edu
Abstract
Basil is a fast-growing crop on aquaponics systems. Previous research has indicated
that basil is
a high cash-value for aquaponics, and the evaluation of specie adaptation in tropical
conditions is
mandatory to recommend new varieties for the UVI Commercial Aquaponic System. Two
trials
were conducted to assess different basil varieties for production in aquaponics. In
the first trial
(Summer 2015), we evaluated five basil varieties (‘Genovese’, ‘Spicy Globe’, ‘Lemon’,
‘Purple
Ruffles’ and ‘Red Rubin’), on a CRD with four replications. In the second trial (Fall
2015), we
evaluated seven varieties (‘Genovese’, ‘Spicy Globe’, ‘Lemon’, ‘Purple Ruffles’, ‘Red
Rubin’,
‘Cinnamon’ and ‘Thai’), on a CRD with three replications. In both trials, 3-week old
seedlings
were transplanted in net pots at a density of 16 plants/m2. The first trial was harvested
every 28
days, and the second trial was harvested before blooming, ranging from every 21 to
28 days.
Plants were harvested four times by “cut and come again”, in which stems were cut
15 cm above
the root and allowed to regrow until the next harvest. Two plants were harvested to
determine
fresh and dry mass. In the first trial, ‘Spicy Globe’ (12.11 kg/m2) and ‘Genovese’
(11.36 kg/m2)
presented the highest total yield and ‘Purple Ruffles’ the lowest (3.49 kg/m2) (p<0.0001).
Plant
fresh weight followed the same trend, and dry weight was higher on ‘Genovese’ (220.5
g/plant)
(p<0.0001). Leaf anthocyanin was higher on the red varieties ‘Red Rubin’ (34.36
ACI) and
‘Purple Ruffles’ (28.35 ACI) (p<0.0001). Chlorophyll content was higher on ‘Genovese’
(48.594
CCI) (p<0.0001). In the second trial, ‘Genovese’ (6.52 kg/m2), ‘Cinnamon’ (5.94
kg/m2) and
‘Spicy Globe’ (5.78 kg/m2) showed the highest total yield and ‘Purple Ruffles’ the
lowest (1.48
kg/m2) (p<0.0001). Plant fresh weight followed the same tendency, and dry weight
was higher
on ‘Cinnamon’ (81 g/plant) (p<0.0001). Leaf anthocyanin differed in all varieties
over time, with
larger values on ‘Purple Ruffles’ (80.5 ACI) and ‘Red Rubin’ (36.5 ACI) (p<0.0001).
Chlorophyll content was a response of variety and plant development, with readings
ranging
from 12 (‘Lemon’) to 18 CCI (‘Cinnamon’) (p<0.0001). On both trials, plant width
and height
increased over time as expected (p<0.0001). Based on our results, we recommend
‘Spicy Globe’
and ‘Genovese’ during Summer and Fall, were Cinnamon’ is also an alternative. The
total yield
reflected the measured plant morphology. Varieties with smaller plant size can be
spaced closely
to increase total yields.
Keywords: Basil (Ocimum basilicum), Aquaculture, Variety trial, Vegetables
Rhuanito Soranz Ferrarezi, Donald Bailey, Seti Balkaran and Jomanni Bernier
University of the Virgin Islands, Agricultural Experiment Station, Horticulture and
Aquaculture
program, RR#1 Box 10,000, Kingshill, VI 00850. E-mail address: rhuanito.ferrarezi@uvi.edu
Abstract
Controlled water stress imposed during the reproductive stage of fruit crops are well-known
for
increasing flowering and fruit quality. However, deficit irrigation is challenging
to apply on
recirculating aquaponics systems due to the use of deep water hydroponic troughs for
vegetable
production. Our study evaluated the effect of partial root and canopy cut performed
before two
different harvest schedules on cantaloupe fruit sugar content. The UVI Commercial
Aquaponic
System used consisted of three main components: fish rearing, solids removal and hydroponic
vegetable production troughs. The hydroponic troughs were 30×1.2×0.3 m with a volume
of 11.3
m3 and a surface area of 214 m2. The water flow rate on the troughs was 125 L/min
for a
retention time of 3 h. Fish waste products were the source of nutrients for plant
growth. Threeweek
old cantaloupe ‘Goddess’ seedlings grown on peat-based substrate were transplanted
into
1.2×2.4-m (2.97 m2) styrofoam rafts on the aquaponics system on Oct 2, 2015 (day after
transplanting, DAT 1). We planted 2 plants/raft spaced every 1.2×1.2 m in a density
of 1.485
plants/m2 and used 12 rafts/trough. Our treatments were the combination of partial
root and
canopy cuts (0%, 25%, 50% and 75%) in two harvest schedules (10 days after cutting
or at fruit
maturation), resulting in 20 treatments, in a CRD with two replications. The root
and canopy
cutting was performed on DAT 37. The first and last harvest were performed on DATs
47 and
64. Sugar content increased only on the treatments with no root cut, 75% and 25% of
canopy cut
and fruits harvested at the maturation (9.1 and 8.4°Brix), with a negative effect
on the treatment
with 75% of root cut, no canopy cut and fruits harvested at the maturation (3.7°Brix)
(p=0.0060).
The treatment with no root or canopy cut and fruits harvested at the maturation promoted
the
highest yield (30,227 kg/ha), indicating a negative effect of the partial cutting
on fruit total yield
(p=0.0072). No treatment response was found on fruit length and width, fruit hardness,
fruit pulp
thickness, leaf chlorophyll and anthocyanin content, root and shoot dry weight and
shoot fresh
weight (p>0.05). Even though our results indicated an increase in fruit sugar content,
more
research is necessary to develop an alternative cultural practice for increasing cantaloupe
fruit
sweetness in aquaponics without compromising total yield.
Keywords: Cantaloupe (Cucumis melo) ‘Goddess’, Recirculated system, Vegetables, Tilapia
(Oreochromis
niloticus), Tropics
Acknowledgements
We thank Luis Carino Jr. and Donna Gonzales (Horticulture and Aquaculture program)
for
technical assistance. Funding for this research was provided by USDA-NIFA-Hatch Funds.