Transcript Effect of Gibberellic Acid (GA3) on Seedlessness of

Effect of Gibberellic Acid
(GA3) on Seedlessness of
Rambutan (Nephelium
lappaceum, Linn.)
MARILYN E. ROMAQUIN, PhD
DANILO T. ELIGIO, PhD
Aklan State University
Banga, Aklan, Philippines
Rationale
 Rambutan (Nephelium lappaceum, Linn.), under the
family Sapindaceae is native to Malaysia and Indonesia.
 It is presently grown and cultivated in Thailand, Burma,
Vietnam, India, Sri Lanka, Australia and Puerto Rico.
 Rambutan is consumed fresh, canned, or preserved.
The colorful fruits are frequently used in displays with
flower arrangements.
 One major drawback for rambutan is its thin edible flesh
and big seeds which makes it relatively
expensive for consumers.
Rationale
 Rambutan flower buds could be induced to produce
functional stamen using a plant growth regulator.
 The problem regarding the quality of rambutan cultivars
could be resolved with the proper timing in the
applications of plant growth regulators and fertilizers.
 Gibberellic acid (GA3) is one of the plant growth
regulators that has gained popularity and demand
among commercial fruit growers. The effect of GA3 in
rambutan production was not yet tested.
 In this study, the influence of GA3 at different
concentrations applied at different times
on the quality of rambutan
was evaluated.
Objectives
The study was conducted to evaluate the effect of GA3
at different times of application and concentration on the
yield and quality of rambutan fruits at harvest. Specifically
it is aimed to:
 determine the effect of different concentrations of
GA3 applied at different times;
 evaluate the effect of time of GA3 application on the
quality of rambutan fruits; and
 find out the interaction effect of GA3 and time of
application on the over-all yield
and quality of rambutan fruits.
Experimental Site
This study was conducted at the Rambutan Project of the
Aklan State University, Banga, Aklan. The site is
characterized by a sloping terrain with a ground elevation
between 10 to 20 meters above sea level. The location
falls under type 3 climate which has no pronounced
season, dry period in February through April and wet
period during the rest of the year. The wettest mouth is
November; the driest month is April (Source: PAGASA –
Roxas City).
Experimental Trees
Nine 8-year old asexually
propagated and bearing
rambutan
trees
with
almost
uniform
vigor,
height and canopy was
used.
Cultural Practices
The following cultural
practices were observed
during the duration of
the research:
 Weeding
 Fertilization
 Pruning
Experimental Design
A Split-plot in Randomized Complete Block Design
(RCBD) with three replications was used in this study.
Main Treatment (A) - Time of application of GA3
A1
- Before Bud Break (BBB)
A2
- Before Full Bloom (BFB)
A3
- Fruit Setting Stage (FSS)
Sub-treatment (B) - Varying concentration of GA3
B1
- 0 ppm (distilled water)
B2
- 50 ppm
B3
- 100 ppm
B4
- 200 ppm
Data Gathered
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
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
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


Total No. of Fruits per
Cluster
Length of the fruit
Fruit Diameter
Weight Per Fruit
Percent Seedless Fruit
Total Soluble Solids
pH of the Fruit at Harvest
Yield Per Branch
Aril Weight
Statistical Tools




F-test
Analysis of Variance (ANOVA)
Randomized Complete Block Design (RCBD)
Duncan’s Multiple Range Test (DMRT)
Results and Discussion
Results presented herein were reduced to the
application of GA3 before bud break which showed positive
response to the induction of seedlessness. Application at
other times did not significantly promote seedlessness.
The results are presented in the succeeding graphs.
Number of Fruits per Cluster
10
a
9
a
ab
8
7
b
6
5
4
3
2
1
0
0
50
100
150
Concentration (ppm)
Figure 1. Effect of GA3 on the Number of
Rambutan Fruits per Cluster.
200
250
Average Length of Fruits (mm)
45
40
a
35
b
b
50
100
b
30
25
20
15
10
5
0
0
150
Concentration (ppm)
Figure 2. Effect of GA3 on the Length of
Rambutan Fruits (mm).
200
250
ab
100
a
90
b
% Seedless Fruits
80
70
60
50
40
30
20
10
c
0
0
50
100
150
Concentration (ppm)
Figure 3. Effect of GA3 on the Percentage
of Seedless Fruits.
200
250
40
TSS (Degree Brix)
35
30
25
20
a
a
50
100
a
b
15
10
5
0
0
150
Concentration (ppm)
Figure 4. Effect of GA3 on TSS (°Brix).
200
250
Results and Discussion
 Production of seedless fruits occurs naturally in
rambutan but rare with an average of 4.45 percent.
 Upon application of 50 ppm GA3, seedlessness
significantly increased to 86.67 percent, attaining 100%
with 200 ppm. This was noted when GA3 was applied
before bud break.
 The consequence of seedlessness is the significant
reduction in the length of fruits but not in diameter and
weight of individual fruits which remained comparable
to the seeded fruits.
Results and Discussion
 Decrease in the length of fruit was attributed to GA3 and
not on the number of fruits, which also significant by
increased with the application of GA3.
 Correlation analysis between length and the number of
fruits was not significant (r=-0.155) while highly
significant correlation was noted between seedlessness
and length (r=-0.673**).
 Weight of aril, the edible portion, was not significantly
affected by seedlessness, but seedless fruits was found to
be significantly sweeter over the seeded ones. This was
disclosed by the positive highly significant
correlation between seedlessness and
total soluble solid (r= 0.83**).
Results and Discussion
 Yield was the same for all treatments. By and large, it
could be inferred that GA3 could induce seedlessness in
rambutan.
 However, it should be applied at the proper stage and
concentration. Based on the results of the study, 50 to
200 ppm GA3 applied before floral bud break could
induced seedlessness.
Findings
 Results showed that the number of fruits significantly
increased with the application of 50 to 200 ppm before
bud break. Length and diameter of fruit, however, were
significantly reduced by GA3, as a consequence, the
weight of fruit likewise decreased.
 Proportion of seedless fruit significantly increased with
the application of GA3 before bud break, which
decreased at the later stages. Aril weight of the fruit
remained comparable among treatments.
Findings
 Fruits harvested from branches applied with GA3 before
bud break were found sweeter than fruits harvested
from branches applied before full bloom and at fruit
setting stage, as shown by the result of total soluble
solids.
 Significantly higher yield was produced from GA3
treated branch before full bloom and at fruit setting
stage due to higher number of harvested fruits.
Findings
 Application of GA3 can increase yield and induce higher
proportion seedlessness in rambutan provided, GA3 is
applied at the proper concentration and time. GA3 at
100-200 ppm sprayed before bud break produced high
proportion of seedless fruits, which could solve problem
of big seeds in rambutan without sacrificing aril weight
and quality.
Conclusion
 Based on the results of the study, GA3
should be used from 100 to 200 ppm
before bud break if the intention is to
induce seedlessness.
Maraming
salamat po!