Effect of defoliation, decapitation and deblossoming on fruit bud differentiation in guava (psidium guajava l.)

1. 1. Appl. Hort., 1(2) :97-100, July-December, 1999
Effect of defoliation, decapitation and deblossoming on fruit bud
differentiation in guava (Psidium guajava L.)
Gorakh Singh, A.K. Singh and S. Rajan
Central Institute for Subtropical Horticulture, Rehmankhera, P. O. Kakori, Lucknow-227107
Abstract
Complete removal of leaves, along with decapitation of shoot was found to be very effective in relation to flower bud differentiation
(FBD), while ringing with partial or complete defoliation along with decapitation of shoots was not able to promote FBD. Decapitation
of shoots in the presence of leaves formed flower buds with the extent of 44 to 63% and 37.0 to 54.0% in Sardar and Allahabad Safeda,
respectively. February, March and April; July, August and September; October, November and December shoots defoliated in May,
October and January formed flower buds two months later than the control shoots. Principal component analysis revealed that the time
of shoot emergence was the decisive factor for FBD in 1, 2 and 3 months old shoots. The defoliated shoots put forth terminal extension
or axillary growth, while in undefoliated ones only terminal growth took place. There is a strong indication that in guava, leaves play
favourable role in flower bud formation.
Introduction
Key words: Guava, defoliation, decapitation, flower bud differentiation.
The role of the main apex in inhibiting lateral bud
development has been studied in many species
(Phillips, 1975), but far fewer investigations have
been made regarding the influence of the developing
and mature leaves on bud growth. Nevertheless, the
inhibitory effects of developing leaves on axillary bud
growth have been demonstrated in Phaseolus
vulgaris (Field and Jackson, 1974) and Brussels
sprouts (Kronenbery, 1973). where, leaf removal
resulted in the stimulation of lateral shoot
development. It appears that no study has been
made so far on the effect of shoot decapitation and
ringing on FBD in guava. Likewise, very little work
has been reported on the effectof defoliation on FBD.
Defoliation and pruning are the main methods in
guava to force the axillarybud resulting into shoots on
which flowerbuds are formed (Singh et al., 1996). The
phenomenon of apical dominance has been explained
by both hormone-balance and nutrient theories, but
the mechanisms involved are complex and the
response of species is so different that many questions
remain unresolved (Phiilips, 1975). Singh et al. (1999)
observed that in different guava cultivars, time of
shoot emergence in has relation with fruit bud
differentiation (FBD) and also observed positive
correlation between vegetative growth and FBD.
Therefore, for accertaining the exact nature of
probable factors governing the formation of flower
buds, certain treatments such as defoliation,
decapitation and ringing were applied to guava shoots,
to observe their relative effects on FBD.
Materials and Methods
The experiment was conducted on eighteen years old
trees of Allahabad Safeda and Sardar.
A. Defoliation
The effect of defoliation was studied under the
followingheads:
1. Defoliation of shoots of varying age-groups
at a fixed period.
2. Defoliation of the same age Shoots at
different periods.
1. Defoliation of shoots of varying ages: A set of
two trees each of Allahabad Safeda and Sardar were
taken in this experiment. Thirty shoots of each age-
group were selected at random, on each tree, and
were defoliated in the month of May, October and
January. These were also tagged for recording
observations on FBD.The same number of untreated
shoots in each age-group were kept as control for
comparison.
2. Defoliation of the same age shoots at different
periods: Thirty shoots of both .the cultivars were
tagged in the months of February, March, April,July,
August, September, October and December for
defoliation in different periods. The selected shoots
were defoliated thrice from March 1993 to March
1994. The data matrix of the FBD percent in 1,2 and
3 months old shoots was subjected to Principal
component analysis (peA) as suggested by Jeffers
(1978).
B. Decapitation of shoots
For studyingthe effectofdecapitation on the FBDofthe
shoots, the foilowingtreatments were applied.
1. Decapitation of March, April, July, September
and December shoots: Generally it is understood
that the terminal buds exert an inhibitory effect on
the axillary buds which remain dormant in its

2. 98 Journal of Applied Horticulture
presence. Shoots of Allahabad Safeda and Sardar
were used for this treatment to see how far the
removal of the terminal buds helped in the activation
of axillary buds with regard to FBD. The present
investigation gives a detailed account of the effect of
decapitation for which 50 March, April, July,
September and December shoots, each of Allahabad
Safeda and Sardar were decapitated after two months
from the date of their emergence and the same
number of shoots were kept as control.
2. Decapitation followed by ringing and partial or
complete defoliation, and ringing followed by
defoliation only: In the defoliation treatments, there
was indication of some important role played by the
leaves in the fruit bud differentiation. It was,
therefore, planned to combine decapitation and
defoliation of shoots with ringing. Experiments were,
therefore, laid out to asses the importance of leaves in
inducing axillary flower buds in the decapitated
shoots. Some shoots were also ringed to see the
behaviour of the terminal buds in the absence of
leaves. For this study, there were four treatments
applied.
i. Shoots decapitated, ringed and completely
defoliated above the ring.
ii. Shoots decapitated, ringed and partially
defoliated with two leaves on each shoot
iii. Shoots ringed and completely defoliated
iv. Completely defoliated and decapitated.
The treatments were given in the second week of
May,with 50 shoots on each tree ofAllahabad Safeda
and Sardar under each treatment.
Results
Defoliation of shoots of varying ages: Flower buds
differentiated on all the defoliated shoots in both the
cultivars, irrespective of the age group, but the
treated shoots formed flower buds about a month
later than the control. It is clear from Table 1 that
February, March and April shoots defoliated in May
formed flowerbuds i.e. 43.3 and 36.6 % as compared
to 63.3 % and 46.6 % in control in Sardar and
Allahabad Safeda, respectively. July, August and
September defoliated shoots formed flower buds i.e.
33.3 and 30.0 % in Sardar and Allahabad Safeda,
respectively as compared to 43.3 and 23.3 % under
control of respective cultivars.
Defoliation of the same age shoots at different
periods: February shoots defoliated in May; April
shoots in May, June and July; August shoots in
September, October and November; September
shoots in October, November and December and
October shoots in November,December and January
did not formed any flowerbud which was contrary to
the behaviour of the control shoots (Table2). Percent
FED was found to be better when February shoots
defoliated in the month of March i.e. 53.0 and 49.0
% in Sardar and Allahabad Safeda, respectively.
However, control shoots showed high percentage of
FBD from March shoots i.e. 60.0 and 70.0 % in
respective cultivars.
Table 1. Effect of defoliation of shoots of varying ages
on FBD in guava cvs. Sardar and Allahabad Safeda
Particulars of Number of Percent of shoots differen-
Shoots Shoots un- tiating into fruit buds
der observe- Sardar Allahabad
tion Safeda
Feb.-Mar.-Apr. 30 43.3 36.6
Control 30 63.3 46.6
Jul.-Aug.-Sep. 30 33.3 30.0
Control 30 43.3 23.3
Oct.-Nov.-Dec. 30 36.6 23.3
Control 30 26.6 33.3
X2 = 6.54, 6 d.f., p=0.25
Table 2. Effect of defoliation of the same age shoots at
different time on FBD in guava cv. Sardar and Alla-
habad Safeda
Particulars Period of
of shoots treatment
------------~~-----------
Shoots differentiating into fruit buds
(%)
Allahabad SafedaSardar
February March (60.0) 53.0
April 17.0
May 0.0
April (69.0) 40.0
May 13.0
June 10.0
May (27.0) 0.0
June 0.0
July 0.0
August (44.0) 14.0
September 11.0
October 7.0
September (43.0) 0.0
October 0.0
November 0.0
September October (27.0) 0.0
November : 0.0
December 0.0
November (37.0) 0.0
December 0.0
January 0.0
December January (39.0) 14.0
February 13.0
March 18.0
(70.0) 49.0
13.0
2.0
(40.0) 31.0
9.0
7.0
(32.0) 0.0
0.0
0.0
(20.) 17.0
9.0
3.0
(46.0) 0.0
0.0
0.0
(58.0) 0.0
0.0
0.0
(31.0) 0.0
0.0
0.0
(63.0) 17.0
12.0
21.0
March
April
July
August
October
Figures in parenthesis refer to control
Decapitation of shoots: The shoots, decapitated in
March, producedmaximum flowerbuds i.e..63.0 and
54.0 % as compared to 60.0 and 38.0 % under control
in Sardar and Allahabad Safeda, respectively(Table3).
Allthe decapitated September and Decembershoots in
both the cultivars produced only vegetative growth,

3. Defoliation, decapitation and deblossoming effects on fruit bud differentiation in guava 99
whereas non-treated shoots differentiated into flower
buds i.e. 32.0 and 53.0 % in respective cultivars.
It is clear from Table 4 that shoot decapitation
followed by ringing-and partial ringing followed by
defoliation had almost negligible influence on flower
bud formation in both the cultivars. While
completely defoliated and decapitated shoots formed
fruit buds i.e. 59.0 and 48.0 % in Sardar and
Allahabad Safeda.
Table 3. Behaviour of shoots, decapitated in different
months
Particulars of
shoots
Period of
treatment
Shoots differentiating into fruit
buds (%)
Sardar Allahabad Safeda
March May 63.0 (60.0) 54.0 (38.0)
April June 44.Q (21.0) 37.0 (27.0)
July September 20.0 (39.0) 13.0 (21.0)
September November 0.0 (27.0) 0.0 (49.0)
December February 0.0 (32.0) 0.0 (53.0)
X2 = 22.44, 4 d.f., p=0.0002; Figures in parenthesis refer to control
Table 4. Behaviour of the decapitated, ringed and
defoliated shoots; decapitated, ringed and partially
defoliated shoots, ringed and defoliated shoots
Treatments Shoots differentiating
into fruit buds (%)
Sardar Allahabad
Safeda
A Shoot decapitated, ringed and 0.0 0.0
completely defoliated
B Shoots decapitated, ringed 0.0 0.0
and partially defoliated
C Shoots ringed and completely 0.0 0.0
defoliated
D Completely defoliated and 59.0 48.0
decapitated
• Sardar ••• Allahabad Safeda
2.0
1.5
e ~
Dec Dec
1.0
0.5 t5 ts ~
Jul
e
Mar
U 0 OO~ .."
_.l.~pr -c,
-0.5 IS'~S~; Jul A A Mar
-.10
I"
-1.5 Feb
-2.0 Feb eA
-1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0
PC I
Fig. 1.Two dimensional ordination of first two PC scores extracted
separately from data matrix for Allahabad Safeda and Sardar
Discussion
Under given climatic conditions, the number of
fruiting primordias which develop in a shoot buds is
influenced by cultivar and nature of treatment. Both
the cultivars under study vary widely in their FBD
ability. Studies of various research workers have also
shown that the proportion of buds in which FBD
occurs all along the length of shoot, varies with the
fruit species (Phillips, 1975).The results indicate that
defoliated shoots of varying ages in both the varieties
form flower buds less in number as compared to
control shoots. While the defoliation of the same age
shoots (shoots of August, September and October) at
different time did not form any flower bud, certain
percentage of February, March July and December
defoliated shoots produced flower buds.' However,
this behaviour is not easy to interpret since the effect
of defoliation depended very much on the influence
exerted by the presence of the main apex. One
interpretation of this effect is that the leaves are
major source of nutrition and hormoriee- necessary
for the development of axillary shoots in guava on
which flower buds are formed (Singh et al., 1999).
The present finding confirms the observations of
Thomas (1983) in Brussels sprouts and Singh (1961)
in mango. However, most of the results do not
support this contention, rather indicates that the
leaves produce substance(s) inhibitory to bud growth
or they deprive the buds of substances necessary for
growth.
Per cent FBD in the shoots defoliated after first,
second and third month of emergence were used as
three variables for principal component analysis. The
analysis revealed (Fig. 1) that the time of shoot
emergence was decisive for FBD in 1,2 and 3 month
old shoots. The figure clearly shows that shoots
emerging in April, May, June and September are not
favourable for FBD whereas shoots emerging in the
months of February, March, July and December are
suitable for FBD. This shows that FBD is more
dependent on season as compared to variety and
defoliation technique. It seems that variety and
defoliation treatment has limited role in explaining
the variability in FBD data. It is also indicated that
shoot of both the varieties under. study are of similar
nature in their behaviour with regard to response to
defoliation.
Results on the decapitation show that the response
to decapitation is different in Sardar and Allahabad.
Sixty per cent and fifty four per cent of Sardar and
Allahabad Safeda shoots differentiated flowerbuds as
a result of decapitation of March shoots. This
emphasises the inhibitory effect of the terminal buds
on the dormant axillary buds of the shoots. It is
evident from the study that the ringed, decapitated
and defoliated shoots in both the varieties fail to form
flower buds. However,' in such shoots axillary
vegetative buds are formed in both the varieties.
There results lead one to believe that the presence of
leaves is essential for the transmission of the flower'
bud forming substances to induce axillary flower
buds. Defoliation and decapitation (combined) had
significant effect on flower bud formation. Since

4. 100 Journal of Applied Horticulture
Referencedefoliation enhances the out growth of axillary buds
in ringed and decapitated shoots, the suggestion of
Kronenberg (1973) that the leaves produce growth
inhibitor(s) which may be transported into the
axillary buds and thus retarding growth, seems valid.
The chi-square test performed to determine whether
or not to reject the idea that with regard to FBD, the
variety and defoliation treatment are independent,
revealed that FBD is dependent on varying age of the
shoots not on the variety. Since the p-value is 0.25,
we cannot reject the hypothesis that variety and
varying age of the shoots are independent.
In our study, how the presence of leaves initiate FBD
in all the decapitated and defoliated shoots and how
it fails to induce FBD in the majority of similar
shoots of September and December is not clearly
understood. Further, probably the optimum set of
conditions required for axillary flower bud formation
purely vary with different fruit crops.
Acknowledgement
The authors are grateful to Dr. S.S. Negi, Director,
Central Institute for Subtropical Horticulture for his
keen interest in the present study and providing
necessary facilities. ,
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