V53n4a16

861

Vol.53, n. 4: pp. 861-872, July-August 2010 BRAZILIAN ARCHIVES OF
ISSN 1516-8913 Printed in Brazil
BIOLOGY AND TECHNOLOGY
A N I N T E R N A T I O N A L J O U R N A L

Floral Biology of Cacauhy (Theobroma speciosum -
Malvaceae)
Márcio Silva de Souza1 and Giorgini Augusto Venturieri2*
1
Laboratório de Ecologia do Fitoplâncton e Microorganismos Marinhos; Departamento de Oceanografia;
Fundação Universidade Federal do Rio Grande; C. P: 96201-900; Rio Grande - RS - Brasil. 2Laboratório de
Evolução Aplicada; Centro de Ciências Biológicas; Universidade Federal de Santa Catarina; C P.: 88.040-900;
Florianópolis - SC - Brasil

ABSTRACT

In the present work, cacauhy´s (Theobroma speciosum) floral biology was studied. Flower buds split their sepals at
14h reaching its maximum at 22h, but all flowers were fully opened at 6:00 h of the following morning. Stigmatic
branches showed exudates, reaching maximum between 6:00 h and 10:00 h at the same day. Ligules and petal hoods
were the floral parts with highest intensity of odour. Flowers were receptive along all the morning and noon of the
anthesis day. Approximately 65% of the flowers were naturally pollinated, but only 0.85% of them set a fruit.
Abscission occurred on its higher frequency at 6:00 h of the second day after anthesis. Controlled pollinations showed
that cacauhy was self-incompatible species.

Key words: self-incompatibility, flower behavior, hybridization, cocoa

INTRODUCTION them. It is also known as “cacauí (at Brazil);
“cacaoy”, “cacaoíllo”, “cacau-rana”, “cacao biaro”,
The Theobroma genus has 22 species and eight are “cupuyh”, “cacao sacha” (at Peru), or “chocolatillo”
Amazonian trees. It has an economic importance (at Bolivia). Although its use is not popular at
both in the past and in the present. In the past, there Amazonia, its pulp is consumed fresh and from its
was cacau-do-Peru (Theobroma bicolor), a pre- seeds, a chocolate can be prepared, considered as
Columbian crop which seeds were eaten toasted and low quality by Cuatrecasas (1964), an opinion that
considered a delicacy (FAO, 1986). At the present, is not shared by Le Cointe (1934) that considered it
there is cocoa (T. cacao) used in the food industry excellent.
of chocolate and the cupuassu (T. grandiflorum) Cacauhy is a median tree that reaches up to 15 m in
considered one of the most profitable crops of height with a straight trunk and a small canopy.
Amazonia, whose pulp has been used to prepare Leaves are coreaceous, distichous, with limb ovate-
juices, ice-creams and sweets (Venturieri, 1993). oblong or elliptic-oblong, with the base sub-
Although cacauhy (T. speciosum) is considered an rounded, asymmetric, with 20-40 cm in height and
economically inexpressive species, it is close 7-18 cm in width, with 8 pairs of lateral nerves
genetically to cocoa (T. cacao) and cupuassu (T. strongly inclined for the apex. Flowers are born in
grandiflorum) and so a possible font of genes for the majority in dense cushions in the trunk and have

*
Author for correspondence: giorgini@ccb.ufsc.br

Braz. Arch. Biol. Technol. v.53 n.4: pp. 861-872, July/Aug 2010

862 Souza, M. S. and Venturieri, G. A.

a strong odour of lemon skin (Fig. 1a); flower buds, 20 seeds surrounded by a white pulp, almost
sepals, petals (except cogules) and staminodes are without odour (Cavalcante, 1988). The cacauhy is
dark red; staminodes are in 5, subulate and the Theobroma species with wider distribution,
alternated with stamens (Fig. 1b); fruits are round- occurring in all the Amazonian Hylea and from it
ellipsoid, with around 10 cm in length slightly up to South of Central America (Ducke, 1953),
pentagon and sulcated, the skin is slightly velveted exceeding the limits of the Hylean flora at the state
and yellow on the ripe fruit; each fruit has around of Maranhão (Cuatrecasas, 1964).

a b
Figure 1 - The cacauhy (Theobroma speciosum): a) flower cushion (photo from G.A. Venturieri); b)
flower details (drawn from Antônio Elielson S. da Rocha).

Hybridisation of cocoa (T. cacao) with other close the hybridization success between cocoa and its
species has been suggested as a strategy to improve relative species such as cacauhy (T. speciosum).
the resistance against "swollen shoot" (Martinson, The temporal patterns of flower development of T.
1972) and “witch’s broom disease” (Addison and cacao, T. speciosum, T. mammosum and Herrania
Tavares, 1952). The first is a virus responsible for cuatrecasana were studied by Young et al. (1987),
serious damages in the cocoa production in Western but generated data were scarce.
Africa; the second is caused by a fungus, In the present work, was described the floral
responsible for significant depletion in the cocoa behaviour of caucauhy (T. speciosum), its pattern of
production in Brazil. Addison and Tavares, (1952) pollen deposition on the stigmatic branches and the
tried to hybridise the Amazonian species of species’ breeding system. Also, by indirect
Theobroma but without knowledge about the methods, the period of receptivity of the stigmatic
breeding system and floral biology of the majority branches was assessed.
of the involved species. Apparently it had limited


Floral Biology of Cacauhy (Theobroma speciosum - Malvaceae) 863

MATERIALS AND METHODS 6L-11, 6L-13 and 6L-16. These were immediately
dissected and their parts grouped into three classes:
The study was carried out between August and 1) ligules and cogules; 2) staminodes and stamens;
September of 1995 using a living collection of the and 3) sepals, ovaries and peduncles. Samples of
Theobroma species "George Basil Bartley", at the each class of flower parts were placed in a
Estação Experimental de Recursos Genéticos do stoppered vial for one hour and then smelled by
Cacau “José Aroldo” - ERJOH in Marituba three different persons. Each person attributed a
(located at Km 17 of the BR 316 highway; Lat. 1° subjective grade from 1 to 3 (1 = odour barely
12' S; Long. 49° 13' W) and belonged to the perceptible; 2 = odour moderately perceptible; 3 =
Comissão Executiva do Plano da Lavoura intense odour immediately perceptible). They did
Cacaueira (CEPLAC), and, during July of 1996, at not exchange opinions about the assay during the
the Empresa Brasileira de Pesquisa Agropecuária – experiment. Six groups of flowers were collected,
Amazônia Oriental (EMBRAPA – Amazônia and three flower part classes were compared by
Oriental) in Belém (Lat. 1° 20' S; Long. 48° 30' W). three observers who attributed one of three different
Both sites are in the state of Pará, in the North of grades to each, so their grades were compared using
Brazil. The plants studied were growing in an a χ2 contingency test for N=162 (6x3x3x3).
Oxisol with red and yellow argilites and a low For three consecutive days, flowers were collected
drainage capacity (Neves and Barbosa, 1983). at 6:00, 10:00, 14:00, 18:00 and 22:00 h, which
According to Köppen’s classification, these sites corresponded to the time of anthesis plus 4, 8 and
have an "Afi" climate (mean temperature of 26 °C, 12 h, and so on until 56 h after anthesis beginning.
air humidity 84 % and mean annual rainfall 2,600 The quantity of exudate on these flowers stigmatic
mm) (Salati, 1985). The identification codes of the branches was observed using a stereomicroscope
plants studied at ERJOH were: 6L-07, 6L-11, 6L- and classified subjectively. Depending to the
13, 6L-16 and 8L-8; and at EMBRAPA – quantity of exudate observed, grades were
Amazônia Oriental, seven plants were studied, attributed as follows: 0 = without visible exudate; 1
identified as A, B, C, D, E, F and G, all labelled in = exudate covering all the stigmatic branches as a
the field with aluminium tags nailed to their trunks. thin layer; 2 = exudate forming a hemispherical
A total of 244 flower buds were labelled close to droplet; and 3 = a copious quantity of exudate,
the anthesis point in order to allow the daily forming a spherical droplet.
blooming pattern of the trees at CEPLAC and Flower receptivity was assessed indirectly by means
EMBRAPA – Amazônia Oriental to be determined. of stigmatic reaction of Peroxidase with a 0.3%
Observations were made at 6:00, 10:00, 14:00, solution of Peridrol (containing 30% of H2O2). On
18:00 and 22:00 h, for four consecutive days. The the first, the second and the third days after anthesis
times of pre-anthesis (the point at which flowers beginning, six flowers were collected each time, at
began to split their sepals); anthesis (when petals 6:00, 10:00, 14:00, 18:00 and 22:00 h. These
were fully open and staminodes had diverged so flowers were taken to the laboratory where their
that the pistil could be seen) and abscission (when pistils were removed and placed on a Petri dish. A
flowers had fallen spontaneously or fell after a light drop of H2O2 solution was carefully deposited on
touch) were recorded. Flower longevity was defined the stigmatic branches only. As the H2O2 reacted
as the time between anthesis and abscission and with the Peroxidase, free O2 bubbles were formed
recorded. During the first two days after anthesis, in the solution. These bubbles were used to evaluate
representative schematic drawings were made of the the Peroxidase reaction level (Zeisler, 1938). After
position of floral whorls (staminodes, ligules, approximately five seconds, the reaction of each
cogules and sepals) at each time of observation. The pistil was subjectively classified as: weak = with
most frequently occurring type (the mode) was used emission of up to 5 bubbles/second; intermediate =
to indicate the phase. During the same period, the with emission of 6 to 15 bubbles/second; or strong
colours of the petals (ligules + cogules), sepals and = with emission of more than 15 bubbles/second.
staminodes of a single plant considered The natural pollination level was evaluated in all
representative of the group were recorded. The the flowers selected and identified for the behaviour
colours were compared and named according to a studies. The flowers were collected after they had
colour chart of Kornerup and Wanscher (1984). fallen naturally or were taken on the fourth day after
At 10:00 h, every day for six days, six flowers were anthesis, then were placed in plastic bags and
collected on their day of anthesis from plants 6L-07, transported to the laboratory, taking care to avoid



the accidental pollination during the transport. The gently. Stigmatic branches were examined using a
stigmatic branches of each flower were taken off at UV microscope (ZEISS/JENA, model Jenalumar
the base and put on slides and then three drops of an 30G 0050) with filters for incident light (G-410)
aqueous solution of Cotton Blue at 0.01% were and for transmitted light (U-204 + 2 x K-425 + B-
added and a coverslip put in place. Slight pressure 422 or 2 x KP-560 + G-247). The number of
was then applied to open the stigmatic branches. pollen tubes that fluoresced bright blue against a
The dye was applied in order to stain the pollen dark blue background were subjectively assigned
exine and make the pollen grains more visible while to three classes: "none" (no pollen tubes observed),
they were being counted. Each stigmatic branch "+" (less than 15 tubes), "++" (16-30 tubes), and
was visually divided into three parts (basal, median "+++" (more than 30 tubes). Pollen grains were
and apical) and the pollen grains on each were considered to have germinated when the pollen
counted up to a maximum of 60 grains. Branches tube was longer than the diameter of the pollen
with more grains than this were classified as having grain. During the observations, abnormalities
“more than 60 pollen grains”. Pearson’s correlation characteristic of incompatibility, such as deposition
coefficient (r) was calculated for the relationship of callose on the walls of cells of stigmatic branches
between the length of time flowers remained on the that had been in contact with pollen, or inhibition of
plant and the number of pollen grains deposited on pollen tube growth, were seen and noted (Knox and
their stigmatic branches. Williams, 1986).
In order to study the occurrence of possible
incompatibilities within and between plants (the
breeding system), flowers from three plants at RESULTS
CEPLAC were self- and cross-pollinated.
Pollinations were carried out according to the The frequencies of sepal splitting were similar for
method described by Venturieri and Ribeiro (1995), the plants at both locations studied (Fig. 2a and 2b).
from 9 to 12 of November of 1996. Fifteen flowers Sepals began to split at 14:00 h (around 15% of the
were pollinated per match. The same number of flower buds). Ruptures began at any point along the
flowers were marked, and left to be pollinated natural seams between sepals and reached their
naturally to serve as a control. The pollinated and highest frequency at 22:00 h (around 50 % of
marked flowers were visited at 3-day intervals up to flower buds). Anthesis occurred between 2:00 and
the 9th day after pollination and again when ripe 6:00 h on the following day. At 6:00 h, all the
(60th day after pollination). The number of fruits flowers were completely open, although some at
was recorded during these visits. Where fruits had CEPLAC (2.5 %) were still splitting their sepals. At
aborted, they were observed to check whether this EMBRAPA – Amazônia Oriental, at the same time,
was due to natural damage or to a possible late effect 40% of flowers were still splitting their sepals (Fig.
of incompatibility. 2b). While some variation could be observed, the
Pollen tube growth was recorded in the flowers highest frequency of anthesis occurred at dawn. At
pollinated with either compatible or incompatible both sites flower abscission occurred from 14:00 h
pollen grains (and where incompatible, the site of on anthesis day, continuing thereafter. At CEPLAC,
incompatibility) from crosses between five plants the highest frequency of abscission occurred at
(6L-7; 6L-9; 6L-11; 6L-13 and 6L-16) from 22:00 h on the day following anthesis (17.3 %) (the
CEPLAC that were matched when possible, and of 06:00 h data were summed with the data from 2:00
which three were self-pollinated and six cross- h, but even taking half of this figure, these data still
pollinated. Pollination was performed at 7:00 to contained the highest proportion of abscission). At
8:30; 10:00 to 11:30 and 14:00 to 15:30 h. The same EMBRAPA – Amazônia Oriental, abscission was at
procedures were also carried out with three plants 6:00 h, i.e., 16 h before CEPLAC, where abscission
from EMBRAPA – Amazônia Oriental, but these was later and more scattered, which was possibly a
were only pollinated between 7:00 and 8:30 h. All populational characteristic. At CEPLAC, more
flowers were collected 24 h after pollination and grains of pollen reached the flowers than at
fixed in FAA (Radford et al., 1974). The pistils were EMBRAPA – Amazônia Oriental, but this seemed
stained with 1 part of 0.1% methyl blue in 1N to have had no influence on setting fruit, because no
K3PO4 (Kho and Baer, 1986) and observed by fecundated flowers remained on the trees at
microscope under UV light. The stigmatic branches CEPLAC. The majority of flowers remained
were then mounted in 90% glycerol and squashed opened on those trees for 24 h.



100 100

Frequency (%)
Frequency (%)

80 a 80 b
60 60

40 40

20 20

0 0
6 10 14 18 22 2 6 10 14 18 22 2 6 10 14 18 22 2 6 10 14 18 22 2 6 10 6 10 14 18 22 2 6 10 14 18 22 2 6 10 14 18 22 2 6 10 14 18 22 2 6 10

Time Time

Pre-anthesis Anthesis Abscission Pre-anthesis Anthesis Abscission

Figure 2 - Frequency of flowers by phases in the flower behaviour of cacauhy (T. speciosum): a) at
CEPLAC/ERJOH in Marituba, PA. N= 160; b) at EMBRAPA – Amazônia Oriental N=
84. At 2 o’clock no observations were made.

With relation to the position of floral whorls, three This was the mature flower configuration that
basic configurations were observed and named as persists for the longest proportion of the flower’s
phase 1, 2 and 3. In “phase 1”, there was little space life (Fig. 3). The exudate appeared soon after the
between the floral whorls; some sepals were still anthesis, reaching its maximum between 6:00 to
joined in pairs and with staminodes slightly parallel 10:00 h on the morning of anthesis and then
to the peduncle longitudinal axis. The ligules and reducing, but maintaining a cyclic variation for the
sepals had internal angles from 30o to 45o. This following two days, always with peaking between
configuration was typical of recently opened 6:00 and 10:00 h (Fig. 4). Peroxidase enzyme
flowers, but it was observed that sometimes flowers activity was strong in the majority of flowers during
that were close to abscission returned to this the three days that they remained on the trees,
configuration. In recently opened flowers and in although it was highest on the first day of anthesis
flowers close to abscission, the staminodes’ apexes (Fig. 4). A close relationship between the presence
sometimes curved towards the centre. When of exudate and Peroxidase activity suggested that
flowers were in “phase 2”, ligules and staminodes the period that flowers are most receptive is
diverged more, with an internal angle of 45o to 60o. between 6:00 and 10:00 h of the first day of
This is the transition between phase "1" and phase anthesis (Fig. 4). Notwithstanding, fertilization was
"3". In “phase 3", ligules were close to the possible during the days that followed, particularly
horizontal plane and staminodes reached their in the early morning.
maximum aperture (internal angle of around 60o).

fase 1 fase 2 fase 3
6h 18 h 6h

Figure 3 - Floral whorls position of cacauhy. Drawings made from the modes of grouped data from
CEPLAC/ERJOH in Marituba, PA (N= 160) and EMBRAPA – Amazônia Oriental (N=
84).

Braz. Arch. Biol. Technol. v.52 n.5: pp. 1201-1208, Sept/Oct 2009


1.0 2.5
0.9
2.4

Grades of exudate
0.8

Peroxide activity
0.7 2.3
0.6
0.5 2.2
0.4
0.3 2.1

0.2
2.0
0.1
0.0 1.9
6 10 14 18 22 2 6 10 14 18 22 2 6 10 14
Time

exudate proxidase

Figure 4 - Averages of grades attributed to the volume of exudation and Hydrogen Peroxide activity
on stigmatic branches of cacauhy flowers (N=425). Grades correspond to the average of
the number of styles observed by time. At 2 no observations were made.

The colours of the flower whorls and times of indicator of flower receptivity. For the plants
observation are given in Table 1. At the times studied, the floral whorls with most intense odour
assigned, flowers parts exhibited colours ranging were ligules and cogules, followed by staminodes
from violet to ruby. From this point on, they and stamens, (Table 2). The group consisting of
became progressively browner. Sepal colours sepals, ovaries and peduncles showed the lowest
changed fast and demonstrated a good correlation odour levels.
with receptivity and as such were an appropriate

Table 1 - Colours of the flower parts of cacauhy (Theobroma speciosum), from opening to fall, taken from the plant
6L-07 at CEPLAC/ERJOH, Marituba PA, Brazil.
Flower Parts
Time
Sepal Ligule Petal Hood Staminode
6:00 The internal surface is violet Violet brown (11- Background pale red (11- Violet brown (11-7F)
brown (11-8E). Externally , a 8F) 3A) with brownish violet
dark ruby (12-7F) (11-8D) lines at the base

10:00 Internally ruby (12-8D) and Ruby darker than Background pastel red Magenta (13-8F)
externally dark ruby (12-8E) on sepals (12-8F) (10-4A) at base dark red
(11-8C) lines
14:00 Internally violet brown (11-8E) As before As before with a brownish As before
and externally dark ruby (12- violet (10-7F) base
8F)
18:00 Internally and externally dark As before As before Dark ruby (12-7F)
ruby (12-8F) with apex dark
purple (14-7F)
22:00 As before As before As before As before
6:00 As before As before As before As before but darker
(12-8F)
fallen Dark violet (16-7F) Violet (15-7F) Internally and externally Dark violet (15-8F)
flower dark violet brown (10-8E)



Table 2 - Odour of the flower parts of cacauhy (T. speciosum) at CEPLAC/ERJOH, in Marituba, PA, Brazil.
Differences in odour by flower part are highly significant according to chi-square test (p< 0.001), N=81.
Grades*
Flower part classes
1 2 3 Means
Ligule and petal hood 0.0% 2.8% 97.2% 2.97
Staminode and stamen 19.4% 69.5% 11.1% 1.91
Sepal, ovary and peduncle 44.4% 52.8% 2.8% 1.58
*
Grades subjectively attributed were: 1= odour perceptible with insistence; 2= odour moderately perceptible; 3= intense odour
immediately perceptible.

The distribution of pollen grains by the position on crossing resulted in 135 flowers being pollinated, 50
stigmatic branches is illustrated in Figure 5. There of which produced fruit (Table 3). The trees
was no significant difference between the naturally observed exhibited variations in their capacity to set
pollinated and unpollinated flowers in terms of the the fruit. Some were mainly compatible (B x C), and
time that flowers remained on trees (based on the t the others partially compatible (A x B, B x A, C x
test, where p = 0.95 and DF = 230) and there was B). Reciprocal crosses were similar in terms of fruit
also no association between the quantity of pollen setting. The majority of the fruits recorded soon
deposited and the time that flowers remained on the after the pollination became ripe (76%). Pollen tubes
tree (Pearson’s coefficient, where r = 0.26 and N= grew both in self-pollinated (incompatible) and
152). For these tests, data from the two flowers that cross-pollinated (compatible) flowers. In both cases,
set fruit were excluded. No fruits resulted from self- pollen tubes reached the ovules and no abnormalities
pollination (45 flowers from three trees). Out- could be observed (Tables 4 and 5).

80
70
60
50
40
(%)

30
20
10
0
´01-10
11-20
21-30
31-40

top
41-50

middle
51-60

>60
base

N. of pollen grains

Figure 5 - Distribution of pollen grains by position on the stigmatic branches of cacauhy (T.
speciosum). Grouped data from CEPLAC/ ERJOH in Marituba, PA (N= 160) and
EMBRAPA – Amazônia Oriental (N= 84).



Table 3 - Fruit set under controlled pollination. Date of: a) 3 days after polination, b) 6 days after pollination; c) 9
days after pollination; d) 60 days after pollination (when ripe). - = aborted flower; + = healthy fruit; * = aborted fruit.
a)
A B C
A --------------- +++++++ - - - - - - - - ++++++++ - - - - - - -
B +++++++ - - - - - - - - --------------- +++++++ - - - - - - - -
C ++++++++ - - - - - - - +++++++++++++ - - ---------------
Control --------------- --------------- ---------------
b)
A B C
A --------------- +++++** - - - - - - - - +++++++* - - - - - - -
B ++++*** - - - - - - - - --------------- +++++++ - - - - - - - -
C +++++++++ - - - - - - ++++++++++++* - - ---------------
Control --------------- --------------- ---------------
c)
A B C
A --------------- ++++*** - - - - - - - - +++++++* - - - - - - -
B ++++*** - - - - - - - - --------------- +++++** - - - - - - - -
C ++++++++ - - - - - - - +++++++++** - - ---------------
Control --------------- --------------- ---------------
d)
A B C
A --------------- ++++*** - - - - - - - - ++++++* - - - - - - -
B ++++*** - - - - - - - - --------------- +++++** - - - - - - - -
C ++++++* - - - - - - - ++++++++++*** - - ---------------
Control --------------- --------------- ---------------

Table 4 - Receptivity of stigma assessed by germination of pollen grains. The number of pollen tubes on stigmatic
branches were estimated subjectively; +++= more than 30 tubes; ++= 16-30 tubes; += less than 15 tubes; none= no
pollen tubes observed. At CEPLAC/ERJOH, Marituba, Brazil, 1995-1996.
Pollination ♀6L-07 ♀6L-11 ♀6L-13 ♀6L-16
time N ♂6L-07 6L-13 ♂6L-11 ♂6L-16 ♂6L-13 ♂6L-07 ♂6L-09 ♂6L-11 ♂6L-11
7:00 01 none + none + none
02 none + none + +
03 + ++ + + ++
04 ++ ++ +++ ++ +++
05 +++ +++ +++ +++ +++
10:00 01 +++ +++ +++ +++
14 :00 01 + +++ +++ +++



Table 5 - Receptivity of stigma assessed by germination of pollen grains. The number of pollen tubes on stigmatic
branches were subjectively estimated; +++= more than 30 tubes; ++= 16-30 tubes; += less than 15 tubes; none= no
pollen tubes observed. At EMBRAPA – Amazônia Oriental, Belém, Brazil, 1996.
♀E ♀F
Pollination time
N ♂E ♂G ♂E ♂F ♂G
7:00 01 +++ ++ +++ + +
02 ++ + +++ +++
03 +++ + +++ none
04 ++ + +
05 ++ +
06 + +
07 + +
08 ++ +
09 ++
10 +

DISCUSSION hoods. The insects that Rodrigues-Silva (2003)
considered to be effective pollinators were abundant
In the present work, the flower buds split their sepals at the time that the present study indicated flowers
between 14:00 and 6:00 h. At 6:00 h, almost all of were most receptive. When flower whorls were in
the flowers were fully open. In Costa Rica, Young et the phase 2 position (Fig. 3), the arrival of
al. (1987) observed that cacauhy flowers split their pollinators was facilitated and they were forced to
sepals (equivalent to the pre-anthesis phase) at 15:00 distribute the pollen grains to the stigmatic branches
h and began to open (equivalent to phase 1) at 20:00 as described above. The floral whorls with most
h) and were not fully open by 9:00 h, although intense odour were the ligules and cogules, followed
between 8:00 and 11:00 h, mature flowers (phase 2 by staminodes and stamens, reinforcing the
to 3) were present. Thus, there was some agreement hypothesis that they were attracting pollinators.
between the two studies here, considering that small Although the Peroxidase reaction showed that
variations were acceptable, due to environmental or cacauhy flowers remained receptive throughout the
even genetic variability. whole time the flowers were on the trees (2-3 days),
The same sequence of odour levels observed for these results could be debatable. Venturieri (1994)
cacauhy whorls has also been described of cupuassu mentioned that senile stigmas of cupuassu (T.
(T. grandiflorum) (Venturieri, 1994), of cacau- grandiflorum) reacted to H2O2 due to an increase in
cabeça-de-urubu (T. obovatum) (Souza and tissue permeability and so the unexpectedly high
Venturieri, 1998) and of cupuí (T. subincanum) levels of H2O2 reaction to pistils on the days
(Rodrigues and Venturieri, 1997). In the case of following anthesis could be an experimental artefact,
cupuassu, the cogules appeared to function as a because the results of pollen tube growth in
dumb waiter for fallen pollen grains, from where pollinated flowers with compatible and incompatible
insect pollinators collected them (Venturieri, 1994). pollen (see Tables 4 and 5) meant that cacauhy’s
It has also been suggested that this is a sheltered stigmatic branches were receptive throughout the
place for Chrysomelidae weevils, which use it for morning and early afternoon of the day of anthesis.
mating and so promote pollination (Venturieri et al., Nevertheless, the Peroxidase reaction was positive
1997). Rodrigues-Silva (2003) considered that the all along the stigmatic branches, suggesting that
flies of the group Bromeliae (Drosophilidae), and pistils were receptive throughout their length, as has
some species of Phoridae, were the effective been observed of (T. grandiflorum) (Venturieri,
pollinators of cacauhy. These insects arrive on the 1994), cacau-cabeça-de-urubu (T. obovatum) (Souza
ligules, passing to the petal hoods, where they come and Venturieri, 1998) and cupuí (T. subincanum)
into contact with the anthers with pollen grains and (Rodrigues and Venturieri, 1997).
then go to the base of the ovary, scraping their backs In the present study, 65.5% of the cacauhy flowers
against the stigmatic branches on the way. These were naturally pollinated (N= 234). This pollination
pollinators were observed feeding at the base petal level was quite high when compared with other



species of the genus, such as: T. grandiflorum (1.6 indirect evidence that the period of receptivity was
%) (Venturieri, 1994), T. cacao (2 - 4 %) (Free, most intense between anthesis and 18:00 h of the
1993; Parvais et al., 1977), T. obovatum (7.5 %) same day (Souza and Venturieri, 1998). Cupuassu
(Souza and Venturieri, 1998) and T. subincanum flowers (T. grandiflorum) begin to split their sepals
(18.7 %) (Rodrigues and Venturieri, 1997), but at any time of the day, but anthesis occurred
lower than Herrania mariae, in which 100% of the between 16:00 and 18:00 h with the natural
flowers were naturally pollinated (Venturieri and deposition of pollen grains occurring at any part of
Silva, 1997). the stigmatic branches and with a period of highest
In cupuassu (T. grandiflorum), hand pollination receptivity from anthesis up to 10:00 h on the
between compatible plants showed that 20% of following day (Venturieri, 1994). Cocoa (T. cacao),
flowers that received 60 pollen grains set a fruit, flowers began anthesis during late afternoon and
while flowers that received more than 400 pollen anthesis was complete at dawn of the following day
grains always set a fruit (Venturieri and Ribeiro- (Free, 1993) with the period that they were most
Filho, 1995). The cacauhy fruit had 20-26 seeds, less receptive being between 10:00 h of the day of
than cupuassu, which had 36 or even 50 anthesis and 13:00 h of the following day
(Cuatrecasas, 1964, Venturieri, 1993), so it was (Sampayan, 1966). In cupuí (T. subincanum), sepal
possible that less pollen would be necessary for a splitting and anthesis were almost simultaneous and
cacauhy flower to set a fruit than for a cupuassu occurred mainly between 2:00 and 6:00 h with the
flower. In cacauhy, only two of the naturally period that they were most receptive being between
pollinated flowers set a fruit: one had a pistil with 59 10:00 h on the day of anthesis and 22:00 h on the
pollen grains and another with 120, so, potentially, following day (Rodrigues and Venturieri, 1997).
more of the naturally pollinated flowers would have Attempts to hybridise those species will, therefore,
received enough pollen to set fruit, but only 0.85% have to take into account the period of receptivity of
of them set a fruit, which was a sign that a the female parts and availability of pollen grains
significant number of flowers were pollinated with from the male parts.
incompatible pollen. In the controlled pollination Considering that the location where the highest
experiment with cacauhy, the majority of flowers frequency of natural deposition of pollen grains that
that had set a fruit, when evaluated on the 3rd day should be the part with the most effective
after pollination, remained on the tree on the 60th pollination, it could be suggested that for hand
day. Considering that the majority of aborted fruit pollinations using cacauhy as a female, the pollen
were damaged by the insects, it could be concluded would preferably be deposited from the middle to
that any incompatibility reactions had already the top third of the stigmatic branches.
occurred before the 3rd day of pollination. The
following three observations suggested that the
incompatibility system in cacauhy was under ACKNOWLEDGEMENTS
gametophytic control, occurring inside the ovules, as
has been observed in cocoa (T. cacao) (Cope, 1962) We thank to the Conselho Nacional de
and cupuassu (T. grandiflorum) (Venturieri, 1994): Desenvolvimento Científico e Tecnológico
a) pollen tubes growing both in cross-pollinated Programa para o Tropico Úmido (proc. No.
(compatible) and self-pollinated (incompatible) 63.00.13/95-0) and the International Foundation for
flowers, b) reciprocal crosses that were similar in Science (Grant no. D/2456-1) for the resources used
their fruit set and c) the site of incompatibility. in the present project. We also thank the
The aim of the present study was to produce a Universidade Federal do Pará, Comissão Executiva
theoretical basis for the search for opportunities to do Plano da Lavoura Cacaueira, and Empresa
hybridise cacauhy (T. speciosum) with other Brasileira de Pesquisa Agropecuária – Amazônia
Theobroma species. Although cacauhy begin to Oriental (EMBRAPA – Amazônia Oriental), for
split their sepals at 14:00 h, they were fully open providing laboratory and field facilities, and to
between 2:00 and 6:00 h the following morning. Edilson de F. Leal, Alessandra de A. Rodrigues,
The flowers of cacau-cabeça-de-urubu (T. Simony S. P. de Souza, Marivana B. Silva, Antônio
obovatum) usually opened between 22:00 to 6:00 h E. da Rocha, for the extraordinary help during the
with the highest deposition of pollen grains on the development of the present work.
upper third of the stigmatic branches and there was



RESUMO Martinson, V.A. (1972), Embryological studies on
hybridisation between Theobroma cacao and
Neste trabalho foi estudada a biologia floral do Theobroma grandiflorum. Canadian Journal of
Botany., 50, 2117-2124
cacaui (Theobroma speciosum). Os botões florais
Neves, A.D. de S. and Barbosa, R.C.M. (1983),
romperam a suas sépalas às 14h com a maior Levantamento detalhado dos solos do Campo de
freqüência às 22h, estando completamente abertas Introdução de Theobroma da Amazônia. (Boletim
às 6 h da manhã seguinte. Os braços estigmáticos Técnico n° 109). CEPLAC- Comissão Executiva do
apresentaram exsudato, com o nível máximo entre Plano da Lavoura Cacaueira, Ilhéus/Itabuna, p. 1-30
06 e 10 horas da manhã do mesmo dia. As lígulas Parvais, L.P., Reffye, P.H. de; and Lucas, P. (1977),
mais as cógulas foram as partes florais com odor Observations sur la polinisation libre chez Theobroma
mais intenso. As flores estavam receptivas durante cacao: analyse mathématique des données et
toda a manhã e à tarde do dia da antese. modélisation. Café Cacao Thé., 21, 253-62
Aproximadamente 65% das flores foram Radford, A.E., Dickison, W.C., Massey, J. R.. and Bell,
C.R. (1974), Vascular Plant Systematics. Harper and
naturalmente polinizadas, mas somente 0,85%
Row Publishers, New York
formou fruto. A abscisão ocorreu com maior Rodrigues, A. de A. and Venturieri, G.A. (1997), Floral
frequência às 6 h do segundo dia após a antese. biology of “cupuí” (Theobroma subincanum) -
Polinizações controladas mostraram que o cacauí é Sterculiaceae. Anais do I Encontro de Botânica
uma espécie auto- incompatível. Econômica de Espécies Nativas da América Latina;
CATI, 21 - 22 de agosto, Campinas/SP/Brasil
Rodrigues-Silva, A de A.(2003), Polinização de cacauí
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