Production regularity of `Ponkan` mandarin trees submitted to

Transcription

DOI: 10.5433/1679-0359.2012v33n6p2163
Production regularity of ‘Ponkan’ mandarin trees submitted to
chemical thinning
Regularidade de produção de tangerineira ‘Ponkan’ submetida a
raleio químico
Maria do Céu Monteiro Cruz1*; Rodrigo Amato Moreira2
Abstract
Alternate bearing is a problem that has influenced the productivity and fruits quality of ‘Ponkan’
mandarin trees. The aim of this research was to evaluate the effect of chemical thinning on alternate
bearing and productivity of ‘Ponkan’ mandarin tree. Ten-year-old plants grafted on ‘Rangpur’ lime
(Citrus limonia Osbeck) were evaluated in a commercial orchard from December 2006 to July 2008.
Five Ethephon concentrations were applied: 0, 150, 300, 450 and 600 mg L-1 in two fruit development
stages (30 mm and 40 mm of transverse diameter). The experiment was set in a 5×2 factorial scheme,
in randomized blocks with four replications. In the first year after chemical thinning with Ethephon the
productivity was evaluated in plants of different treatments. In the second year the alternate bearing and
the productivity were evaluated. The chemical thinning promotes yield regularity in ‘Ponkan’ mandarin
trees, with the application of Ethephon at concentrations between 300 mg L-1 to 600 mg L-1. Plants
sprayed with 600 mg L-1 of Ethephon produced fruit higher amounts in following year to thinning.
Key words: Citrus reticulata Blanco, alternate bearing, Ethephon
Resumo
Para a tangerineira ‘Ponkan’, a alternância de produção é um problema que tem influenciado a qualidade
das frutas e a produtividade. A finalidade desta pesquisa foi avaliar os efeitos do raleio químico sobre
a alternância de produção e produtividade da tangerineira ‘Ponkan’. Foram utilizadas tangerineiras
‘Ponkan’ enxertadas sobre limoeiro ‘Cravo’ (Citrus limonia Osbeck), de um pomar comercial com dez
anos de idade, no período de dezembro de 2006 a julho de 2008. As plantas foram pulverizadas com
cinco concentrações de Ethephon: 0, 150, 300, 450, 600 mg L-1, em dois estádios de desenvolvimento
das frutas: 30 e 40 mm de diâmetro transversal. Foi utilizado o esquema fatorial 5×2, disposto em
blocos casualizados, com quatro repetições. No primeiro ano, após a aplicação do raleio químico com
Ethephon, foi avaliado o rendimento da produção nas plantas dos diferentes tratamentos. No segundo
ano foram determinadas a alternância de produção e a produtividade. O raleio químico promove a
regularidade de produção em tangerineira ‘Ponkan’ com aplicação de Ethephon em concentrações entre
300 e 600 mg L-1. As plantas pulverizadas com a concentração de 600 mg L-1 produziram alta quantidade
de frutos no ano subsequente ao raleio.
Palavras-chave: Citrus reticulata Blanco, alternância de produção, Ethephon
Engª Agrª, Pós-D.Sc. Profa. do Deptº de Agronomia, Universidade Federal dos Vales do Jequitinhonha e Mucuri, UFVJM, Campus
JK, Diamantina, MG. E-mail: [email protected]
2
Engº Agrº, Doutorando do Programa de Pós-Graduação em Fitotecnia, Universidade Federal de Lavras, UFLA, Lavras, MG.
E-mail: [email protected]
*
Author for corespondence
1
Recebido para publicação 11/07/11 Aprovado em 12/09/12
Semina: Ciências Agrárias, Londrina, v. 33, n. 6, p. 2163-2172, nov./dez. 2012
2163
Cruz, M. C. M.; Moreira, R. A.
Introduction
The mandarin ‘Ponkan’ tree produces one
of the most appreciated tangerines to in natura
consumption due to the facility of removing the
bark and gores, so it is cultivated in various regions
of the world. However, this cultivar is the behavior
of alternate bearing.
The alternate bearing, characterized by excessive
production interspersed with years of low production,
is a problem in ‘Ponkan’ mandarin culture. This is
because in years of greater production, the fruits
are small and have low quality, which make their
marketing difficult, according to market demand for
in nature fruit consumption, which prefers largesize fruits.
Techniques that can be used to alleviate this
problem include fruit thinning with the application
of exogenous phytoregulators. This practice has been
done to reduce the fruit amount, improve quality
and reduce the alternate bearing effect by changing
the source-sink relationship. The enhancement
of carbohydrate availability was associated with
an improvement of fruit set and yield of citrus
trees (GOLDSCHMIDT, 1999). The effects of
carbohydrates on fruit growth are relationship by
a wide body of evidence including studies on fruit
thinning (IGLESIAS et al., 2003) because the fruit
growth depend of assimilates supply rate from
sources (GARCÍA-LUIS et al., 2002).
The thinning can increase the fruit size and
crop value. Moreover, it can promote the flowering
in the following year. Because the carbohydrates
exhaustion for fruit in years of high production
influences the flowering in subsequent year due
the flowers number produced is extremely high in
comparison with the number of fruits that the tree
can support until ripening. However, to achieve
significant increase in fruit size requires a drastic
reduction in the fruits number (SCHWARZ;
KOLLER; NIENOW, 1992). This results in
significant reduction in total yield crop, although
it can economically offset through increasing of
the fruit size produced (GUARDIOLA; GARCÍALUIZ, 2000). Because chemical thinning is an
alternative aimed at differentiated markets, such as
table fruit market, as well as be able to reduce costs,
improve quality and can add value.
In ‘Montenegrina’ mandarin (C. deliciosa
Tenore), the alternate bearing was broken
in a satisfactory manner using the Ethephon
concentration of 200 mg L-1 + 3% of urea (SOUZA
et al., 1993). However, the Ethephon thinning
application to promote the fruit quality improvement
and alternate bearing reduction depends on the
age of plants, of thinning completion time and
environmental interaction conditions. Sartori et al.
(2007) observed no reduction of alternate bearing
in ‘Montenegrina’ mandarin with the 200 mg L-1
Ethephon concentration, as no observed effect on
the thinning of fruit.
The improvement of the productive process
with the application of growth regulators has been
reported by other researchers (LEITE; CRUSCIOL;
SILVA, 2011, CRUZ; MOREIRA; ARAUJO,
2011). However, the results are variable due to
differences between the cultivars, concentrations
of growth regulators used and the interaction with
the conditions of the cultivation region, making
himself necessary research to know its effects on
physiological behavior and productive of plants.
The phytoregulators application such as
Ethephon
(2-chloroethylphosphonic
acid),
favors the increase in fruit size by increasing the
metabolites availability for the remaining fruit. In
addition, chemical thinning reduces the problem of
alternate bearing in ‘Ponkan’ mandarin to avoid the
plant depletion due the reduction of fruit number
excessive per plant. Thus, the aim of this work
was to evaluate the effect of chemical thinning on
the alternate bearing and productivity of ‘Ponkan’
mandarin.
2164
Production regularity of ‘Ponkan’ mandarin trees submitted to chemical thinning
Material and Methods
The research was developed in a non-irrigated
commercial orchard situated in Perdões 21°05’27”
(S) and 45°05’27” (W), southern Minas Gerais State,
Brazil. The region’s average altitude is 900 meters
and climate type is Cwb, characterized by hot and
wet summers and dry and cold winters according
the Köppen classification. Data of temperature,
precipitation and relative humidity were recorded
from thinning completion (Figure 1).
Figure 1. Average temperature, relative humidity and rainfall during the experimental period 2007 and 2008 in
Perdões, southern Minas Gerais State, Brazil.
Source: Elaboration of the authors.
It was used ten-year-old ‘Ponkan’ mandarin
trees (Citrus reticulata Blanco cv. Ponkan) grafted
on ‘Rangpur’ lime (C. limonia Osbeck) and planted
with spacing of 6 m between rows and 3 m between
plants. The fertilization was performed according
to soil and leaf analysis, splited in four applications
and cultural treatments and pest control were
performed according to technical recommendations
for the culture.
In the first year, 2007, to promote the chemical
thinning, plants were selected by productive
potential, so that all plants subjected to treatment
had a significant quantity of fruit. The treatments
consisted of five Ethephon concentrations: 0,
150, 300, 450 and 600 mg L-1, applied at two
fruit development stages: 30 mm and 40 mm of
transverse diameter.
The experiment was set in a 5×2 factorial
scheme, five Ethephon concentrations and two fruit
development stages in randomized block with four
replications. The experimental plots were composed
of seven plants and the evaluations in the three
plants of the center plot.
The plants were sprayed with commercial
product ZAZ®, soluble concentrate with 480 g L-1
2-chloroethylphosphonic acid. The applications
were carried in crown full extent (internal and
external) to promote plant uniformity thinning after
the period of fruit physiological drop in January
2007.
2165
In the second year, 2008, to observe the effect
of chemical thinning for the previous year on
occurrence of alternate bearing and productivity, the
ethephon application was not realized.
stages for features evaluated. It was observed
influence of different Ethephon concentrations
(p<0.05) on fruit yield in year that was done the
thinning and in harvest of following year.
At harvest, in June 2007 and 2008, it was
determined the production per plant in boxes of
22 kg and yield per area, calculated as the plants
number per area according to spacing. The yield
production was determined considering fruit
size characteristics, thus it was evaluated for the
transverse and longitudinal diameters to verify if
production was in accordance with the standard
required by the destination market. These standards
were considered in the fruit above 58 and 60 mm in
diameter, longitudinal and transverse, respectively.
The estimated plant production showed
linear growth with the increasing of Ethephon
concentrations applied in the following year the
thinning. In plants that were sprayed in 2007 with
600 mg L-1 concentration, the estimated production
was 3.8 boxes of 22 kg per plant, representing an
increase of 79.3% compared to plants that were not
sprayed with Ethephon. In these plants the results
from the 2008 harvest were higher than those
observed in 2007, about 4.35 boxes of 22 kg per
plant and increase of 128.3% in relation the plants
that were not submitted to thinning (Figure 2a).
During 2008, plants were evaluated in relation to
the fruit size produced and alternate bearing, which
was calculated considering the plants number that
showed total absence of fruit. To evaluate the size
ten fruits were harvested per plant at the median
part of the crown of each treatment to determine the
mass (g), transverse and longitudinal diameter (mm)
and the juice yield (%) determined by relationship
of juice volume extracted by juicer orange from ten
fruits by its mass. From the variation of production
evaluated in the two years the alternate bearing
index was calculated using the formula I = 1/(n-1)
x {|(a2-a1)|/(a2+a1)+|(a(n)-a(n-1))|/(a(n)+a(n-1))},
where n = number of years, and a1, a2, ..., a(n-1),
a(n) = yield of the corresponding years (PEARCE;
DOBERSEK-URBANC, 1967).
Data were submitted to variance analysis to
evaluate differences between the factors and the
polynomial regression to fit models, chosen on the
basis of biological phenomenon and the significance
of regression coefficients, p ≤ 0.05.
Results and Discussion
In plants sprayed with the highest Ethephon
concentration, the estimated yield per hectare was
2,414 boxes of 22 kg in 2008 harvest an increase
of 1,356 boxes compared to plants that were not
subjected to thinning (Figure 2b). In 2007 harvest
the yield was 2,107 boxes of 22 kg ha-1 in plants that
were sprayed with 600 mg L-1 concentration. The
differences observed in yield of crop production in
2007 can be attributed to the small size of fruit in
plants that were not subjected to thinning with those
sprayed with the lowest Ethephon concentrations,
hence the fruit majority was classified as noncommercial production.
This difference in the production yield shows that
the thinning favored the alternate bearing reduction
in the following year after its implementation. The
low crop production in 2008, measured in plants
that were not submitted to thinning and then sprayed
with the Ethephon lowest concentration (150 mg
L-1) in 2007 can be attributed the alternate bearing
observed in some plants of these treatments, while
all plants subjected to 300 mg L-1 concentrations
thinning showed not alternate bearing (Figure 3).
There was not interaction between Ethephon
concentrations applied and the fruit development
2166
in Perdões, southern Minas Gerais State, Brazil.
Production regularity
5.0 of ‘Ponkan’ mandarin trees submitted to chemical thinning
Boxes of 22 kg ha -1
Boxes of 22 kg plant -1
3.0
2.5
2.0
1.5
1.0
0.5
0.0
5.0
4.5
4.0
3.5
3.0
2.5
2.03,000
1.5
2,500
1.0
0.52,000
0.0
1,500
3,000
1,000
2,500
500
2,000
0
1,500
0
a
2007 Ŷ = 2.1175 + 0.0028x r2 = 0.90
2008 Ŷ = 1.905 + 0.004075x r2 = 0.88
2007 Ŷ = 2.1175 + 0.0028x r2 = 0.90
b
2008 Ŷ = 1.905 + 0.004075x r2 = 0.88
Boxes of 22 kg ha -1
Boxes of 22 kg plant -1
4.5
amandarin tree submitted to chemical thinning
Figure
2. Yield
per
andproductivity
productivity
in 'Ponkan'
Figure
2. Yield
perplant
plant(a)
(a) and
(b)(b)
in ‘Ponkan’
mandarin
tree submitted to chemical thinning in Perdões,
4.0
in Perdões,
Minas
Gerais
State,
southernsouthern
Minas Gerais
State,
Brazil.
3.5 Brazil.
2007
Ŷ = 1,175.21
+ 1.554x r2 = 0.90
b
2008
Ŷ = 1,057.28 + 2.26162x r2 = 0.88
150
300
450
Ethephon concentrations (mg L-1 )
1,000
600
2007 of Ŷthe
= 1,175.21
Source: Elaboration
authors + 1.554x r2 = 0.90
500
2008
Ŷ = 1,057.28 + 2.26162x r2 = 0.88
This difference in the 0 production yield shows that the thinning favored the alternate bearing
0
150
300
450
600
reduction in the following year after its implementation.
The low
crop
production in 2008, measured in
Ethephon concentrations
(mg L-1
)
plants that were not submitted
to thinning
andofthen
Source:
Elaboration
the sprayed
authors with the Ethephon lowest concentration (150 mg
L-1) in 2007 can be attributed the alternate bearing observed in some plants of these treatments, while all
concentrations
thinning
not thinning
alternate bearing
3).
plantsThis
subjected
to 300in
mgthe
L-1 production
difference
yield
showsshowed
that the
favored(Figure
the alternate
bearing
reduction in the following year after its implementation. The low crop production in 2008, measured in
Figure 3. Alternate bearing (a) and alternate bearing index (b) evaluated at ‘Ponkan’ mandarin in 2008, following year
Figurewere
3. Alternate
bearing
and alternate
index
(b) Ethephon
evaluated at 'Ponkan' mandarin in 2008,
plants
not submitted
to (a)
thinning
and
thenbearing
sprayed
with the
to that
chemical thinning
application
in Perdões,
southern
Minas Gerais
State, Brazil. lowest concentration (150 mg
following
year
to
chemical
thinning
application
in
Perdões,
southern
Minas Gerais State, Brazil.
L-1) in 2007 can be attributed the alternate bearing observed in some plants of these treatments, while all
b
not alternate
bearing (Figuredecreasing
3).
plants subjected
to 300 mg L-1 concentrations thinning showed
a
increasing fluctuation
fluctuation
Alternate bearing (%)
30
60
10
50
0
40 mm
Alternate bearing index
30 mm
60
0.50
0.45
0.40
0.38
0.38
Figure 3. 50
Alternate bearing (a) and alternate bearing index
0.40(b) evaluated at 'Ponkan'
0.35 mandarin in 2008,
0.32
0.35
40
following year to chemical thinning application in Perdões, southern Minas Gerais State, Brazil.
b
0.30
b
20
30 mm
0
40
40 mm
150
300
450
b
30
20
Source:
Elaboration of the authors.
10
0
0
600
Alternate bearing index
Alternate bearing (%)
a
0.25
0.20
decreasing fluctuation
0.15 increasing fluctuation
0.10
0.500.05
0.450.00 0.38
0.40
0.38
0.40
0.35
0
150
300
450
600
0.32
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
150
300
450
600
150
300
450
600
Ethephon
concentrations
L-1 ) Londrina, v. 33, n. 6, p. 2163-2172,
Semina:
Ciências(mg
Agrárias,
2012 (mg L-1 )
Ethephonnov./dez.
concentrations
2167
Similar results were observed by Souza et al. (1993) in 'Montenegrina' mandarin decreasing the
increaseapplication.
in yield due
to chemical
Similar
results
were
by Souza
al. Ethephon
alternate
bearing
in observed
a satisfactory
manner etwith
Considering
thethinning.
linear behavior in
(1993)relation
in ‘Montenegrina’
mandarin
decreasing
to increased production, it can be justified by Ethephon
concentrations
were used
promote
The high
productionwhich
observed
in to2008
in
the alternate bearing in a satisfactory manner
-1 -1
concentration
plants
subjected
to
600
mg
L
the thinning, noting that some plants that were sprayed with concentration of 150 mg L did not produce in
with Ethephon application. Considering the linear
chemical thinning shows that the fruit amount
yearinofrelation
2008, compared
to plants
of other treatments
behavior
to increased
production,
it can which showed no alternate bearing (Figure 3a). This can
in plants influences the production of following
be noticed
by alternate
bearing index
that were
ranged from 0.32 to 0.40 (Figure 3b) that according with the
be justified
by Ethephon
concentrations
which
year because of carbohydrate amount that is used
used formula
to promote
the thinning,
that some (1967) can vary between 0 and 1; the closer to zero the
proposed
by Pearce noting
e Dobersek-Urbanc
(GOLDSCHMIDT, 1999), exerting a regulatory
plantsvalues,
that were
sprayedthewith
of 150 variation indices of plants sprayed with a concentration of
the smaller
yieldconcentration
fluctuation. However,
effect on yield production. This result suggests that
mg L-1 did not produce
in year of 2008, compared to
-1
is avariation
practice that
should
be done in
‘Ponkan’
decreasing
relative
to previous
year
and the
150 mg L Ethephon and without thinning showedthinning
plants of other treatments which showed no alternate
mandarin
every
because,thinning.
generally, plants
plants
of other
the variation
signified an
increasetree
in yield
dueyear,
to chemical
bearing
(Figure
3a).concentrations
This can be noticed
by alternate
that produce small amount of
fruits
have excessive
The ranged
high production
in 2008 in plants subjected to 600 mg L-1 concentration chemical
bearing index that
from 0.32observed
to 0.40 (Figure
production in following year.
3b) that
according
proposed
by influences the production of following year because of
thinning
showswith
that the
the formula
fruit amount
in plants
With respect to fruit mass was observed quadratic
Pearcecarbohydrate
e Dobersek-Urbanc
(1967) can vary between
amount that is used (GOLDSCHMIDT, 1999), exerting a regulatory effect on yield production.
0 and 1; the closer to zero the values, the smaller behavior with the highest value of 218.2 g estimated
-1
This result suggests that thinning is a practice that should be done in ‘Ponkan’ mandarin tree every year,
the yield fluctuation. However, variation indices of with the Ethephon concentration of 316.6 mg L ,
plants that produce
small
of fruits
have excessive
production
in following
year.
represented
an increase
of 11.49%,
compared
plantsbecause,
sprayedgenerally,
with a concentration
of 150
mgamount
L-1 which
to
fruit
mass
evaluated
in
control
treatment
plantsg
respect
to fruit
mass decreasing
was observed quadratic behavior with the highest value of 218.2
Ethephon and With
without
thinning
showed
(Figure 4a).
variation
relative
to the
previous
yearconcentration
and the plants
estimated
with
Ethephon
of 316.6 mg L-1, which represented an increase of 11.49%,
of other concentrations the variation signified an
compared to fruit mass evaluated in control treatment plants (Figure 4a).
yield of juice (%)
Ma ss (g )
FigureFigure
4. Mass4.(a)
and(a)
yield
(b)juice
measured
in fruits of
mandarinmandarin
in 2008, following
year to chemical
Mass
andjuice
yield
(b) measured
in ‘Ponkan’
fruits of 'Ponkan'
in 2008, following
year to
thinning
application
in
Perdões,
southern
Minas
Gerais
State,
Brazil.
chemical thinning application in Perdões, southern Minas Gerais State, Brazil.
aa
270
240
210
180
150
120
90
60
30
0
Ŷ = 200.582 + 0.125x - 0.000219x2
R2 = 0.87
50
bb
40
30
Ŷ = 35.02979 + 0.0212222x - 0.3*10 -4x 2
R2 = 0.77
20
10
0
0
150
300
450
600
2168
The behavior observed on the mass of mandarins can be attributed to high production in plants that
behavior
observedwith
on the
mass of concentration
mandarins thinning.
The
juice yield
highnumber
mass
wereThe
subjected
to thinning
Ethephon
of 600 mg
L-1high
. In these
plantswas
the due
highthe
fruits
can be attributed to high production in plants that were observed in these fruits. Moreover, during the fruit
per plant probably limited the fruit development, which is dependent of the supply assimilates (GARCÍAsubjected to thinning with Ethephon concentration growth and ripening period, there was sufficient
-1
LUIS
et mg
al., L2002).
These
results
showed
thenumber
strong relationship
between(Figure
source-sink
the excessive
. In these
plants
the high
fruits
of 600
water availability
1), thatwhich
may have
favored
pernumber
plant probably
theinfruit
development,
the GARCÍA-LUIZ,
filling of juice vesicles.
fruit
per plantlimited
influence
its size
(GUARDIOLA;
2000).
which is dependent of the supply assimilates
to transverse
and longitudinal
Similar behavior was observed in the juice yield Regarding
(Figure 4b) with
the largest percentage
of 38.8%
(GARCÍA-LUIS et al., 2002). These results showed
-1
diameters evaluated in mandarins after chemical
estimated
with
the Ethephon
concentration
of 353.7
the strong
relationship
between
source-sink
whichmg L , that represented increase of 11.23% compared to
thinning (Figure 5) were not observed significant
plants
that werefruit
notnumber
subjected
thinning.
Theinhigh
the excessive
pertoplant
influence
its juice yield was due the high mass observed in these
differences
between
different
Ethephon
size (GUARDIOLA;
fruits.
Moreover, duringGARCÍA-LUIZ,
the fruit growth2000).
and ripening period,
there
was
sufficient
water
availability
(Figure
concentrations applied to promote thinning
in
Similar
behavior
was the
observed
juice
yield the following year after the application. Different
1), that
may have
favored
filling in
of the
juice
vesicles.
(Figure Regarding
4b) with the
largest
percentage
of
38.8%
behavior
was observed
in 2007,
an increase
in
to transverse and longitudinal diameters
evaluated
in mandarins
after chemical
thinning
estimated with the Ethephon concentration of fruits diameter in plants sprayed with higher
(Figure 5) were
not observed significant differences between different Ethephon concentrations applied to
353.7 mg L-1, that represented increase of 11.23% concentrations of Ethephon.
promote
thinning
in thethat
following
yearsubjected
after the application.
Different behavior was observed in 2007, an
compared
to plants
were not
to
increase in fruits diameter in plants sprayed with higher concentrations of Ethephon.
Figure 5. Diameter transverse and longitudinal measured in fruits of ‘Ponkan’ mandarin tree submitted to chemical
Figure
5.inDiameter
transverse
andGerais
longitudinal
measured in fruits of 'Ponkan' mandarin tree submitted to
thinning
Perdões, southern
Minas
State, Brazil.
chemical thinning in Perdões, southern Minas Gerais State, Brazil.
90
2007
Diameter (mm)
80
70
60
50
transverse
40
30
longitudinal
20
Ŷ = 66.4913 + 0.01855x
r2 = 0.85
Ŷ = 61.44 + 0.0146x
r2 = 0.78
10
Diameter (mm)
0
2008
90
80
70
60
50
40
30
20
10
0
transverse
0
150
300
longitudinal
450
600
This result may have occurred due the thinning has not been promoted in the second year of
2169
This result may have occurred due the
thinning has not been promoted in the second
year of evaluation, so that all plants that produced
maintained its fruits natural quantity that had
lower availability of assimilates. This is because,
the fruit growth is supported by several evidences
including the increase of source-sink as a result of
fruit thinning (IGLESIAs et al., 2003) and to change
the characteristics related to fruit size is necessary
to reduce the fruit number per plant (CRUZ et
al., 2010). For this, during the initial stage of
fruit development is necessary to apply growth
regulators which ethylene operates instead as the
hormonal activator to promote thinning (IGLESIAS
et al., 2007).
Plants sprayed with 600 mg L-1 of Ethephon
produced higher amounts of fruit in the following
year to thinning.
Another aspect observed in plants submitted
to thinning with the application of 600 mg L-1 of
Ethephon in 2007, is that the yield per plant was
high in 2008, possibly in function of greater amount
of assimilates available due to the smaller number of
fruits in the previous year. This behavior shows that
the following year these plants may exhibit alternate
bearing. And to avoid the problem chemical thinning
should be a practice adopted by the producers of
tangerines, order to maintain appropriate reserves to
regulate the production over the years, maintaining
a profitable activity.
GARCÍA-LUIS, A.; OLIVEIRA, M. E. M.; BORDÓN,
Y.; SIQUEIRA, D. L.; TOMINAGA, S.; GUARDIOLA,
J. L. Dry matter accumulation in citrus fruit is not limited
by transport capacity of the pedicel. Annals of Botany,
London, v. 90, n. 6, p. 755-764, 2002.
Results of fruit size and production in following
year of the Ethephon application suggest that the
thinning practice should be performed every year
in ‘Ponkan’ mandarin for improvement in their
quality. However, for the thinning be effective on
quality fruit is necessary Ethephon concentrations
appropriate use, according to fruit development
stage at the time of thinning, of climatic conditions
and thinning intensity on fruit and leaf abscission
that can affect the quality and yield.
Conclusions
The chemical thinning with the application of
Ethephon at concentrations between 300 mg L-1 to
600 mg L-1 promotes yield regularity in ‘Ponkan’
mandarin trees.
References
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químico em relação à disposição na copa. Ciência e
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Production regularity of `Ponkan` mandarin trees submitted to

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