Tech. Bull. Fac.. Agr. Kagawa Univ. , Vo1.51, No. 1 , 1
-
4 , 1999Morphological observations of floral initiation
and
development
of Schlumbergera
X
buckleyi
( T . ~ o o r e )
Tjaden
Seiichi FUKAI and Masanori Gor
Morphological changes in shoot apex during the reproductive development of Schlumbergera X buckleyz were determined by using a scanning electron microscope. The meristems enlarged and started to produce perianthes after 7-10 days of short day conditions. About 25 perianthes were produced in the following next 10 days. The apex became flat and the center of the flattened apex caved in. The stamen primordia then appeared on the flattened apex and developed from inner to outer whorls. The pistil primordia appeared on the edge of the concave. Stamen primordia grew upward and developed anthers and filaments. The upper position of pistil (style) also grew upward and the top position of the style (stigma) lobed into 8 parts. At same time ovules developed on the inside of the ovary.
Key words : Floral intiation, Schlumbergera
Introduction
Christmas cactus ( ~ c h l u m b e r ~ e r a X buckleyz (T. Moore) ~ j a d e n ) , called 'Denmark cactus' in Japan, is an important pot-plant during winter in Japan. This cactus has flattend foliaceous stems. The stem consists of 3-4 cm in length flat shoots (phylloclade)
.
The top part of each phylloclade (areoles) have an apical and some axillary buds. One to three buds develop into new phylloclades under non-inductive conditions. Floral initiation occurs under short day conditions"'. Morphological changes of the shoot apex during reproductive development have not been described in detail in Cactaceae plants. Floral development of Schlumbergera was reported only in a simple hand ~cketch'~'. The aim of this work is to determine the morphological changes in shoot apex during reproductive development of Schlumbergera X buckleyi.Materials and Methods
Mother plants of Schlumbergera X buckleyz cv. Super Koniger were grown in a greenhouse with a 4h1 night break. Short day conditions (IOhr photoperiods) started from 15th September in 1997. At this time premature phylloclades were removed. Top phylloclades were collected at
5
day intervals until flowering.Collected samples were immediately fixed with FAA (formalin
:
acetic acid:
70% ethanol, 5:
5
:
90). Following fixation, shoot apices were dissected under a binocular microscope. The specimens for scanning electron microscope (SEM) were then dehydrated in an ethanol-acetone series and critical point dried. After coating with Pt, specimens were observed with SEM ( ~ i t a c h i , S-2150).2 Tech. Bull. Fac. Agr. Kagawa Univ., Vol. 51, No. 1 , 1999
OLIVE 香川大学学術情報リポジトリ
FUKAI and Go1
:
Floral initiation and development of Schlumbergera X buckleyiResults and Discussion
One or two meristems at the superior part of phylloclades enlarged and started to produce perianthes after 7-10 days of SD (Fig. 1 - 2)
.
About 25 perianthes were produced in the next 10 days (Fig. 1 -3).
All perianthes showed a similar shape, sharpened top and no hair on both adaxial and abaxial sides. In Cactaceae outer perianthes are usually protective and colourless, for example, Gymnocalycium has scaly outer perianthes, Notocactus has hairy outer perianthes and Echznocereus produces areoles first on the floral tube.The apex enlarged and became flat (Fig. 1-4). The center of the flattened apex caved in (Fig. 1-5). The stamen primordia appeared on the flattened apex (Fig. 1-6). Acropetal development of floral organs reversed of this stage, i.e. stamen primordia developed from inner to outer whorls. Pistil primordia appeared on the edge of the concave (Fig. 1-7). Stamen primordia grew upward and developed anthers and filaments ( ~ i ~ . 1-8). The upper position of pistil (style) also grew upward and the top position of style (stigma) lobed into 8 parts. At the same time ovules developed on the inside of the ovary (Fig. 1
-
9).
After 30-35 days of SD, basic floral parts had been completed. The flower buds grew longitudinally and showed dorsiventral development. Inside the flower bud, during growth of perianthes, outer whorls of stamens were detached from inner whorls, resulting in two separated whorls of stamens, once flowered.
Literature cited
(1) YONEMURA, K.. and H.. HIGUCHI. 1975. The (2) YONEMURA, K. 1976. The control of' flowering in control of' flowering in christmas cactus .. christmas cactus. NOUGYOUOYOBIENGEI 51
:
Influence of' photoperiods to flower.. Bull. Aichi 1395- 1398.Agric Res.. Cent. sex. B 7 40-44.
(~eceived October 30, 1998)
Fig. 1 Floral initiation and development of Schlumbergera .x buckleyi.
1. Initial stage of' floral apex. x600, bar=50p m, 2. The apex started to produce perianthes. x200, bar=200p m, 3. Apex continued to produce perianthes. x200, bar.=200p m, 4. Apex enlarged and became flat. x200, bar=200p m, 5. The center of flattened apex caved
in. x200, bar=200p m, 6. The primordia of stamens appeared from inner to outer whorls. The primordia of' pistils appeased on the edge of the concave. x150, bar=200p m,
7. Stamen and pistil primordia developed. x80, bar=500p m,
8.
Stamen primordia developed into anthers and filaments. The top part of' the pistil developed into a stigma. x50, bas=lrnm, 9. Ovules. x150, bas=200pm,Tech. Bull. Fac. Agr. Kagawa Univ., Vol.51, No. 1 , 1999
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