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Culture Characteristics for Phalaenopsis

 
 

The beautiful orchids, Phalaenopsis pot plant, have had the highest price among the ornament plants for a long time. However, because of over-supply, the price decreased sharply in 2008. Plants with low quality have been driven out the market. Only high quality orchids are of benefit. This paper discusses the basic techniques to produce high quality Phalaenopsis.

 

1.         Special characteristics of the organs for Phalaenopsis

The important organs for Phalaenopsis are the roots, leaves and spikes.

 

1.1   Roots

The functions of roots include fixing the plant in the substrate and absorbing water and nutrients. The root contains chlorophyll, so the natural color is green. Roots have the ability for photosynthesis and assimilation. The adequate environment for roots is moist (vapour) and not soaked with water.

The nutrients dissolved in water cannot be adsorbed by roots directly. The nutrients are adsorbed with the vapour in the air. The adequate substrates for Phalaenopsis must be able to provide moisture, fresh air (oxygen) and nutrients.

If the pot material is transparent, light can pass through the pot wall and provide the energy of photosynthesis. Healthy roots are green and bright.

 

1.2   Leaves

The most important organ for Phalaenopsis is leaves. Leaves have the photosynthesis ability for carbon fixation and the assimilation function to store the available carbon. Except of Ca and Mg, nutrients can be adsorbed into leaves directly. The required carbon sources for spikes and flowers are provided from leaves.

 

1.3   Spikes

The natural color for spikes is green. Spikes contain chlorophyll and have the same photosynthesis ability same as for leaves and roots. However, the assimilation materials are not sufficient for development of spikes and blossoms. So the required dry matter for spikes and blossoms is provided by leaves.

The priority of dry matter distribution for Phalaenopsis differs from that of other plants. Roots are the first to obtain dry matter. The ranking of dry matter distribution is rootsleavesspikesblossoms.

 

2.     Coexistence of vegetable and reproductive phase

Most orchids have vegetative and reproductive stages. The plants at the vegetative stage are in the state of growing and developing, and plants at the reproductive stage are in the state of spiking and flowering. The distinction between the two stages is so obvious for many orchids. Oncidium is a typical orchids. At the vegetative stage, the dry matter is produced and stored in pseudobulbs. At the reproductive stage, the leaves stop the photosynthesis function, and the required nutrients of spikes and blossoms are taken from pseudobulbs.

Phalaenopsis has special characteristics for vegetative and reproductive stages.  Plants developing from tissue culture plantlets to reach the mature stage, they are in the vegetative stage. As these mature plants are moved to a cooling environment for spiking, they are in the reproductive stage until the length of spike reaches to 3-5 cm. However, two stages coexist in the flowering phase. The spikes are lengthened continuously and buds appeared (reproductive stage). The leaves accumulate dry matter and send it to spikes and blossoms (vegetative stage); that is, the required dry matter of spikes and blossoms are taken from leaves. The leaves need to supply the dry matter to spikes and blossoms in the flowering stage.

The microclimate control and fertilization work are important at the flowering stage. The leaves must be maintained at optimal day and night temperature. The light intensity and period are also important. The nutrients need to be supplied correctly. So the leaves must accumulate enough dry matter and send it to spikes and flowers to ensure flower quality.

 

3.     Factors affecting Phalaenopsis quality

3.1   Genotype

The genotype characteristics of the Phalaenopsis variety include flower color, pattern, flower size, flower number, numbers of spike, multi or no branches, and stem height, etc.

 

3.2   Healthy conditions

The plant must mature enough before cooling. Enough dry matter must be stored in plants. The plants must be protected against disease, pest damage, viruses, chemical damage and salt accumulation in substrate.

Figure 1. These plants are in good conditions for cooling treatment

 

3.3   Environment

The environmental factors, such as day temperature, night temperature, relative humidity, light period and intensity must be kept at the optimal range.

The interaction of genotype, health conditions and environment needs to be emphasized. The genotype decides the maximum possible expression for flower quality. For example, the orchids with little white flowers, P. amabilis, containd genes for more twenty flowers. If the plant is mature enough and the cooling environment is appropriate, the grower can obtain more than twenty flowers for each plant. However, the number of flowers will decrease if the plant is immature, or has been damaged by disease or pests, or if the temperature or light intensity are not maintained well.

The effect of microclimate on other flower qualities is described below:

 

3.3.1        Temperature difference of vegetative stage and cooling stage

The numbers of spikes is affected significantly by the temperature difference between the vegetative and cooling phases. The "Mansanfong" variety is used to illustrate the effect of temperature difference on number of spikes. The adequate day and night temperature for the vegetative stage is 28and 26, respectively. If the cooling temperature of day and night is kept at 25and 20, 100 these plants have one spike. As the cooling temperature of day and night is maintained at 23 and 20, 40 of these plants have spikes and 60 of these plants have one spike. At the environment of 20 day temperature and 18 night temperature, 100% of these plants have two spikes.

 

3.3.2        The difference between day and night temperature at flowering stage

The symbol DT represents the difference between day and night temperature at the flowering stage. With increasing DT, the length of spikes (or stems) is lengthened. With decreasing DT, the length of spikes (or stems) is shortened.

Figure 2. DT increase, the length of spikes is too long

 

3.3.3        Day temperature at flowering stage

If the day temperature at the flowering stage is the same or higher than that of the vegetative stage, a leaf will appear in the stem. It is called as “Keiki’s”. Despite the day temperature not being higher than the temperature of vegetative stage, it is still higher than the normal condition and the high day temperature will reduce the flower quality. The position of the first bud is heightened, all buds will be blocked up in the end of stem, the flower color will fade and the number of branches is decreased.

Figure 3. Keiki’s of the Phalaenopsis

 

Figure 4. All buds will be blocked up in the end of stem because the day temperature is too high

 

3.3.4        Night temperature at flowering stage.

If the night temperature at the flowering stage is higher than the adequate condition, the number of blossoms is decreased and the flower size is reduced.

 

4.           Diversity characteristics of Phalaenopsis varieties.

The required qualities are two or more spikes, multi-branching, bright color, and 40-to 75-cm height in The Netherlands. According to the Culture Guide of Floricultura b.v., the adequate environment conditions for Phalaenopsis are as follows:

 

Table 1. Adequate environment conditions for Phalaenopsis

 

Day temp

Night temp

Light intensity

Vegetative phase

28

26

4000-6000lux

Cooling

20

18

7000-8000 lux

Flowering phase

23

20

7000-8000 lux

 

However, the growers usually find that many varieties cannot produce the required quality according to these environment conditions.

In the orchids greenhouse, the leaf colour of some varieties turned red and dark (Figure 5) in The Netherlands. Some varieties are still induced to spike at the growing regions (day temp. 28℃, night temp. 26℃) (Figure 6). Some varieties cannot induce any spikes at the cooling regions (day temp. 20℃, night temp.18℃) (Figure 7).The reason for these results can be explained by the diversity of Phalaenopsis varieties.

 

Figure 5. Leaves colour of different varieties was found that turned into red and dark at the same light level

 

Figure 6. Some varieties still be induced to spike at the growing regions

(day temp. 28℃, night temp. 26℃)

 

Figure 7. Some varieties can not be induced any spikes at the cooling regions

(day temp. 28℃, night temp. 26℃)

 

5.  Classification of the Phalaenopsis characteristics

5.1   According to the culture temperature

Seven types of Phalaenopsis varieties are classified by optimal day and night temperature for the vegetative stage:

A. 31-33℃ / 25-26℃, such as V3, P. Sogo Yukidian

B. 28-30℃ / 24-25℃, such as P. amabilis

C. 28-30℃ / 21-22℃, such as D. Queen Beer

D. 24-25℃ / 20-21℃, such as P. Taipei Gold

E. 21-22℃ / 18-19℃, such as P. Fortune Saltzman

F. 26-31℃ / 21-24℃, such as D. Sin-Yuan Golden Beauty

 

5.2   According to light intensity

The required light intensity of the Phalaenopsis is influenced by the growing stage. The required light intensity of mature plants is usually higher than that of small size plants. A typical variety of big white flower, V3, P. Sogo Yukidian is used to illustrate the levels of light intensity in different stages.

 

Table 2. The require light intensity at different stages for P. Sogo Yukidian

4.0 '' pot

25000 lux

3.0 '' pot

18000 lux

2.0 '' pot

10000 lux

flask

5000 lux

 

The effects of environment on the flower quality are presented as the following case.

The beauty blossom of three spikes is showed in Figure 8. This variety is grown at Pingtung County, southern Taiwan. High day and night temperature (32℃/26℃) and high light intensity (25000 lux) was provided. Then plants were sent to the cooling room (day and night temperature was 23℃ /18℃, light intensity was 28000 lux). As the healthy and mature plants were placed in cooling rooms, three spikes are induced. Thus larger and more beautiful blossoms were produced.

Figure 8. The beauty blossoms of three spikes for V3, P. Sogo Yukidian

 

Some plants were transported to the New York, USA. The microclimate in the greenhouse for the growing stage was 22℃ (day) and 20℃ (night). The light intensity was maintained at 16000 lux. In this condition, these plants did not have the enough sources for photosynthesis. The accumulated dry matter was insufficient for further utilization. With decreasing temperature with the season change and the spikes were induced. The quality of spikes and blossoms did not appropriate for market requirement.

 

Figure 9. The quality of spikes and blossoms of V3, P. Sogo Yukidian in New York

 

From the illustration of above case, the important of the characteristics of variety need to be emphasized, which explains why many varieties of Phalaenopsis have been sent to The Netherlands, some varieties had excellent flowering quality. However, many varieties did not appear accepted quality.

 

6.  Selection of the adequate varieties for The Netherlands

6.1   The greenhouse microclimate

The microclimate of the greenhouse for Phalaenopsis for The Netherlands is described in Table 1. The day and night temperature are 28℃ and 26℃ for the vegetative stage and 20℃ and 18℃ for the cooling phase. So the selection of varieties of Phalaenopsis to provide to this country need to meet the requirements of temperature and light intensity listed in the Table 1.

 

6.2   Required of variety for The Netherlands

The basic requirements of varieties are the genotype and plantlet conditions

The genotype and others conditions of adequate varieties are as follows.

A.    Double or more spikes

B.     Medium or large size of blossoms, at least 8 cm

C.     Nnumber of flowers is 6 at least for each spike

D.    Bright color of blossoms

E.     Compact size, for more plants can be placed per square meter

F.      No disease, insect damage, viruses, chemicals damage, salt accumulation in the substrate. Leaves and roots are healthy.

 

About the author:

Professor Chiachung Chen, Ph. D.

Biosystems Engineering Laboratory
National ChungHsing University

250 KuoKuang Rd.,

Taichung, Taiwan 40227

Tel: 886-4-22857562, Fax: 886-4-22857135

Web site: http://bse.nchu.edu.tw

Email: ccchen@dragon.nchu.edu.tw