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Plant Archives
Vol. 20, Supplement 2, 2020 pp. 2363-2368 e-ISSN:2581-6063 (online), ISSN:0972-5210
STUDY OF FAILURE OF FERTILIZATION IN DATE PALM
(PHOENIX DACTYLIFERA L.) BARHI CV.
Salah A.M. Abd-Elhaleem
1
, F.M. Abd El-Latif
2
, H.E.M. El-Badawy
2
, B.M. AbdAlla
1
and S.F. El-Gioushy
2
*
1
Horticulture Research Institute, Agricultural Research Center, Giza, Egypt.
2
Department of Horticulture, Faculty of Agriculture, Benha University, Egypt.
*Corresponding author: E-mail: sherif.elgioushy@fagr.bu.edu.eg, gioushy_ah@yahoo.com;
Abstract
Fertilization is necessary to generate a new fruits in juvenile palm tree. This study was conducted on the date palm Barhi cv. during
2018 and 2019 seasons, respectively. Which is characterized by the failure of fertilization 15 years old Growing in sandy soil In the
Agricultural Research Station, Qassasin Egypt. there is the apparent failure of fertilization in the orchards of date palms barhi cv.
thought that the reason for this phenomenon is the impossibility of flower for fertilization prospect absence and atrophy of
ovule, deformity of stigma and absence embryo sac. of failure fertilization in barhi date palm or production of fruit
undeveloped. So conducted study the an abnormal flowers which caused the failure of fertilization in date palms cv. To
improve fruit set, where there is pure fertilization failure of the success of the set of the carpel which has an egg dissection of
the female flower that was carried out from the palm tree which is fertilized failure. Absence and atrophy of ovule, deformity
of stigma and absence embryo sac. leads to failure of fertilization in barhi date palm or Production fruit undeveloped most of
the Parthenocarpic fruits on bunches and have significant influence on the economic value of fruits in this physiological type.
Keywords: Date Palm, Barhi, Pollination, Fertilization and Parthenocarpic fruits
Introduction
Date palm (Phoenix dactylifera L.) is one of the most
important fruit trees that all palm farmers in the world are
interested in because of their high economic and nutritional
importance. Egypt occupies the first place globally in
production, so attention is paid to the behavior of pollination
and fertilization, which leads to an increase in the amount of
crop. date palm is a dioecious plant show separate male and
female trees. Both female flowers of the date palm are
formed in a special type of inflorescence called a spadix,
staminate flower consists of 3 carpels surrounded by a short
perianth. Pollination occurs by wind and by artificial
transferring of pollen grains collected from male strands onto
female inflorescence. The fertilized carpel grows and
develops faster than the other two carpels, carpels degenerate
and drop shortly after pollination (Osman et al., 1974). The
formation of abnormal multi-carpel flowers and fruits
become a mature fruit, whereas the remaining two with 6 to 7
carpels were reported by Cohen et al. (2004) and Al-Khalifah
et al. (2007). Cohen et al. (2004) characterize a low fruit
setting phenotype which was found widely among tissue
culture-produced date palms of Barhi cultivar. Most flowers
in such trees turn into Parthenocarpic fruit lets having three
carpels. Moreover, supernumerary carpels are formed in
severe cases, and other flower domination of the fertilized
carpel to become fruit over the remaining two carpels due to
a competition on space and nutrition; embryo abortion of the
other two carpels shortly after fertilization. abnormalities
include distortions of carpels and stigmas can be detected
revealed the development of one carpel only and a reduction
in size of the adjacent two carpels. It can be seen also that the
septa located between carpels are formed by the fusion of
their margins. However, this fusion is incomplete, forming
cavities, one per septum, arranged radially from the base of
the ovary to the base of the stigma. Therefore, it can be
concluded that the abnormal behavior of the developing fruits
may be due to: the absence of the zygote; the damage
occurring in the embryo sac and endocarp layer; the
reduction in embryo tissue which become the main reason of
embryo growth failure (Ali and Sahar, 2015). Female flowers
of date palm have three carpels surrounded by a short
perianth. After fertilization, one of the carpels grows and
develops to reach the final growth phase. Carpels may
continue to grow and develop into seedless fruit even if they
are not pollinated. These fruits either drop or remain on
bunches until the maturity stage. This was due to the
unsuccessful fertilization of the carpels in which they grow to
form fruits. Such fruits are called parthenocarpic or poly
carpels fruits, However, under normal conditions, only one
carpel develops into a fruit, no clear answer is provided to
explain the development of a single carpel at the expense of
the two adjacent carpels. Investigators confirmed that two
carpels degenerate after pollination Osman et al. (1974)
studied the development of date palm fruit at very early
stages of development, and found that the fertilized carpel
grows and develops faster than the other two carpels, and the
carpel started to enlarge in size at the end of the third week of
pollination. On the other hand, parthenocarpic fruits were
observed on date palm plants propagated by tissue culture
almost in all experimental trees (Damankeshan and Panahi,
2013). The trees derived from tissue culture in comparison to
trees consequent from offshoot showed much more primary
flowers, but an increase in the number of seedless fruits or on
the other hand the high percentage of parthenocarpic fruits
were observed.
Failure of fruit set
Off-types are quite common among tissue culture-
produced date palm trees which are often characterized with
a low fruit setting capacity. Most flowers in such trees turn
into parthenocarpic fruitlets having three carpels. In severe
cases, supernumerary carpels are formed. Other flower
abnormalities include distortions of carpels and stigmas. The
2364
abnormalities in most cases one is alleviated in older trees,
with approx equal to 50% of trees reverting to normal within
10 years from transplanting. Many flowers on the abnormal
trees have impaired pollen tube elongation, with growth
being limited to the stigma or to regions near its point of
attachment to the carpel. Directional growth of pollen tubes
ceases and tubes grow in different directions or stop growing
completely (Cohen et al., 2004). This phenomenon is locally
known as 'sheiss' has been lately noticed on tissue culture
'Barhi' date palm at 'Alqassim' area Although the
phenomenon has also been noticed in other date palm
cultivars, its occurrence in 'Barhi is more serious often
reaching 59-86% (Ali-Dinar and Alkhateeb, 2005). Over the
past few years, several researchers investigated the
phenomenon to identify the nature and possible causes of the
problem reported that the failure of normal fruiting in young
tissue culture of date palm trees cv. Barhi was probably due
to many interrelated events that lead to a slow growth of
pollen tube at early stages of fruit growth and which may be
accentuated by the relatively high abscisic acid (ABA)
contents during this period. In conclusion, most of these
abnormalities mentioned previously recover in most cases as
the plants get old (10-year-old). Furthermore, all these
abnormalities were also observed in date palm propagated by
offshoots which is the normal method of propagation for date
palms (Alkhateeb et al., 2006). This was supported by the
finding of Ali-Dinar and Alkhateeb (2005) and Djerbi
(2000). They indicated that the plant showed a substantial
improvement in vegetative growth and set normal fruit as the
plant get older. They concluded that this may probably be to
the relatively longer juvenile period of these plants induced
by unstable interrelated factors and seemed that tree age
plays a central vital role in these events. Ali-Dinar and
Alkhateeb (2005) studied microscopically the reproductive
process from a thesis too early stages of seed development in
collected samples of pistils, ovaries, and young fruit at 2-day
intervals during the first 3 weeks after anthesis and
pollination and at weekly intervals thereafter for normal and
abnormal (sheiss) in Barhi date palm cultivar. They indicated
that events of the reproductive process showed that pollens
grew normally on the stigmatic surface and the pollen tubes
were progressing within the style 2-4 days after pollination in
tissue culture and vegetative offshoots Barhi date palm. Six
to 10 days after pollination, pollen tubes of vegetative
offshoots and tissue culture trees (with few incidences of
abnormal fruiting) had already entered the ovary while those
of young tissue culture trees (with a high percentage of
abnormal fruiting) were slowly progressing within the style.
Ovule fertilization as estimated by the initial endosperm
division was observed 2 weeks after pollination in vegetative
offshoots and old tissue culture trees. However, inner and
outer integument in the ovary of young tissue culture trees
became less intact and separated from each other reflecting a
possible subsequent failure of normal fruit setting due to
failure of the fertilization process. Fruit development was
quite normal in offshoots and old tissue culture trees 6 weeks
after pollination. Differences in pollen tube growth and the
fertilization process between Barhi date palm trees may
reflect possible physical or hormonal related factors that
prevent normal progress of the reproductive process in young
tissue culture trees. Multiple carpels Normally date palm
female flower has 3 carpels. After successful pollination and
fertilization, only one carpel develops to fruit while the other
two shrink and die (Alkhateeb and Ali-Dinar, 2002). Often,
in some micro propagated date palm cultivars, female
flowers possess more than 3 carpels.
Field level
Somaclonal variations in date palm plants can be
permanent (genetic stable variations) or temporary
(epigenetic variation). While the genetic variations in plants
are fixed and difficult to be changed, epigenetic variations
are unstable and mostly result from physiological changes.
Plants with epigenetic variation normally recover with time
once the causes of these physiological changes are removed
(Skirvin et al. 1994). Several factors may contribute to the
occurrence of somaclonal variations in tissue cultured date
palm, namely: growth regulators, type of explants used in
micropropagation process, genome typical nature of plants,
length of duration cultured tissues are kept and frequency of
subculturing and proliferation rate of cultured tissues
(Alkhateeb et al. 2006). Types of somaclonal variations in
date palm are following: On the other hand, parthenocarpic
fruits were observed on date palm trees propagated by tissue
culture almost in all experimental trees (Damankeshan and
Panahi, 2013). El-Jarrah, and Al-Ani (1981).The pollinated
and fertilized carpel grow and enlarge in size shortly after
pollination. Al-Bakr (1972) reported that date palm embryo
starts to develop one week following pollination, occupying
one-third of the ovule cavity and reaching its full length six
to seven months later as the fruit matures. The development
of a single carpel towards the stage of fruit maturity may be a
result of unsuccessful pollination and/ or fertilization of the
developmental stages of date palm carpel to become mature
fruit, on the expense of the other two carpels, have been
studied in details by Long (1943), Osman et al. (1974)
remaining two carpels; domination of the fertilized carpel to
become fruit over the remaining two carpels due to a
competition on space and nutrition; embryo abortion of the
other two carpels shortly after fertilization. perianth around
the carpels which affected their progress of growth.
Observations on abnormal behavior of tissue culture-derived
date palm have been reported by McCubbin et al., (2000).
Such abnormality includes slow growth rate with deformed
leaves and wide leaflets, variegated leaves, non-flowering
and low fruit setting. Similar findings were also found in
tissue culture-derived populations of date palms, such as
abnormal multi carpel flowers and fruits with six to seven
carpels (Djerbi, 2000; Al-Wasel, 2000; Cohen et al., 2004;
Al-Kaabi et al., 2007; Al-Khalifah et al., 2007).
Materials and Methods
This study was conducted on the palm trees of Barhi cv.
during 2018 and 2019 seasons respectively which is
characterized by the failure of fertilization 15 years old Growing
in sandy soil In the Agricultural Research Station, Qassasin
Egypt. To find out the reasons why pollination and
fertilization are not successful. Feminine floral samples were
taken on the first day of opening the flower pod. Specimens
were killed and fixed for at least 48 hrs. in F.A.A (10ml
formalin, 5ml glacial acetic acid, 35 ml distilled water, and
50 ml ethyl alcohol 95%). The selected materials were
washed in 50% ethyl alcohol, dehydrated in a normal butyl
alcohol series, embedded in paraffin wax of melting point 56
o
C, sectioned to a thickness of 20 microns, double-stained
With Erythrosin and Crystal Violet, cleared in xylene and
mounted in Canada balsam (Nassar and El-Sahhar, 1998).
Were analyzed microscopically and photo micro graphed.
Study of failure of fertilization in date palm (Phoenix dactylifera L.) Barhi cv.
2365
Anatomical sections of the internal structure of normal and
abnormal flowers and setting showed the development of
flower in normal behavior, but in, it was found that no zygote
and embryo sac was detected in the ovary during the
developmental stages of abnormal flower.
There is the apparent failure of fertilization in the
orchards of date palms barhi c.v thought that the reason for
this phenomenon is the impossibility of flower for
fertilization prospect absence and atrophy of ovule, deformity
of stigma and absence embryo sac of failure of fertilization in
barhi date palm or production fruit undeveloped. So
conducted study the abnormal flowers which caused the
failure of fertilization in date palms cv. To improve fruit set.,
where there is pure fertilization failure of the success of the
set of the carpel which has an egg dissection of the female
flower that was carried out from the palm tree which is
fertilized failure. Absence and atrophy of ovule, deformity of
stigma and absence embryo sac leads to failure of
fertilization in barhi date palm or production fruit
undeveloped most of the Parthenocarpic fruits on bunches
and have significant influence on the economic value of
fruits in this physiological type.
The objective of this study is to increase the fruit set
and productivity and improve fruit quality of Barhi date
palm.
The shape of feminine flowers of Barhi date cultivar
The yellow color is creamy, the ovary is three carpels
with a short style on it. The stigma is surrounded by three
petals and three cepals (Fig.1) After completion of the
pollination, the tube of the vaccine passes through the stigma
and then the style goes to the ovary fertilizes the egg and
grows one of the carpels in size and Decays the other two
carpels, including oocytes (Osman et al., 1974).
Fig. 1 : Morphological aspects of Barhi flower date palm cultivars.
Fig. 2 : Normal and abnormal developing fruit of Barhee date palm cultivar
Salah A.M. Abd-Elhaleem et al.
2366
Fig. 3 : Longitudinal section of normal flower
Fig. 4 : Cross-section in normal flower
Fig. 5 : Longitudinal section in abnormal fruits
Fig. 6 : Longitudinal section in abnormal flower showed two
carpals
Fig. 7 : Cross-section in normal flower one of the three ovule
eggs Atrophy
Fig. 8 : Cross-section in normal flower
Fig. 9 : Longitudinal section in abnormal flower One of the
two ovules in the Atrophy
Fig. 10 : The cross-section of the egg is abnormal
Study of failure of fertilization in date palm (Phoenix dactylifera L.) Barhi cv.
2367
Fig. 11 : Across section in a normal egg.
Fig. 12 : Cross-section in normal fruit after four-week
fertilization
Fig. 13 : Longitudinal section in normal fruit after four-week
fertilization Anatomy of flower development of Barhi date
cultivar
Female flowers of date palm have three carpels
surrounded by a short perianth. After fertilization, one of the
carpels grows and develops to reach the final grow the phase.
Carpels may continue to grow also develop fruit un seedless.
This was due to the unsuccessful fertilization of the carpels in
which the fruit grow parthenocarpy or undeveloped (Fig. 2).
generally it under normal conditions, only one carpel
developed into fruit, Investigated confirmed that two carpels
aborted after pollination. the fertilized carpel grows and
develops faster than the other two carpels, and the carpel
started to enlarge in size at the end of the third week of
pollination Osman et al. (1974). On the other hand,
parthenocarpic fruits were observed on date palm trees
propagated by tissue culture (Damankeshan and Panahi,
2013).
The anatomical forms show the internal of flowers and
fruits normal are shown in Longitudinal section (Figure 3)
showed flower in normal behavior, the Members of
femininity it consists of the ovary, style and stigma around
by the perianth. (Fig: 4) Cross-section in normal flower
showed the presence of three eggs inside the ovaries contains
embryo sack.
Figure 5 showed the abnormal behavior. Atrophy in the
oocyte and lack of egg nucleus and embryo sac, which leads
to fertilization failure and The passage of the vaccine tube is
narrow, leading to the difficulty of penetration into the egg.
(Fig: 6 )The longitudinal section of an abnormal flower
shows two carpals one of which has an oocyte and the other
has done embryo sack. (Fig: 7) One of three eggs by atrophy
and the other two eggs in good condition. (Fai:8) showed The
absence of ovule is a cause of fertilization failure (Ali and
Sahar, 2015) can be concluded that the abnormal behavior of
the developing fruit may be due to the absence of the embryo
sac the damage that occurs in the embryo sac and endocarp
layer; reduction in fetal tissue which has become a major
cause of embryo development in the failure.
Figure 9 The longitudinal section of the abnormal one
flower of two ovules in the dystrophy and the presence of
malformations in the stigma and the size of the ovary, which
leads to the failure of fertilization. (Fig.10) showed The
Cross-section of the egg is abnormal before the fertilization
process. The observed atrophy of the egg and the contents of
the egg include the atrophy of the external and internal wall
of the fetus and the atrophy of the fetal sac and the nucleus of
the egg are unclear. (Fig.11) A cross-section in a normal egg
showing the presence of the egg in its normal size and the
presence of the components of the egg (inner wall and
external, fetal sac and the nucleus of the egg). (Figs. 12,13)
Cross-section and longitudinal section in normal fruit after
four-week fertilization One of the carp appeared to form
zygote grow and to be developed fruit but the two carbine
miscarried.
Conclusion
Definitively, from the acquired results, it can be
concluded that ,Absence and atrophy of ovule, deformity of
stigma and absence embryo sac Leads to failure of
fertilization in Barhi date palm or Production fruit
undeveloped most of the parthenocarpy fruits on bunches and
have significant influence on the economic value of fruits in
this physiological type.
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Study of failure of fertilization in date palm (Phoenix dactylifera L.) Barhi cv.
