How to produce the high quality Phalaenopsis The beautiful orchids, Phalaenopsis pot plant, have the highest price of the ornament plants for a long time. However, due to the over-supply, the price is decreased sharply in 2008. Low quality flowers have been drove out the market. Only the high quality orchids could obtain the benefit. The topic of this paper is to discuss the basic techniques to produce the high quality Phalaenopsis. 1. The 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 fix the plant in the substrate and absorb water and nutrients. The structure of root contains chlorophyll, so the natural color is green. Roots have the ability of photosynthesis and assimilation. The adequate environment for roots is surrounded with moist (vapour) and not to soak into water. The nutrients dissolved in the water can not be adsorbed by roots directly. The nutrients are adsorbed with the vapour in the air. So the adequate substrates for Phalaenopsis must have the ability to provide the moisture, fresh air (Oxygen) and nutrients. If the pot material is transparent, the light can pass the pot wall and provide the energy of photosynthesis. The color of health roots is green and bright. 1.2. Leaves The most important organ for Phalaenopsis is leaves. Leaves have the 1
photosynthesis ability for carbon fixation and the assimilation function to store the available carbon. The nutrients can be adsorbed into leaves directly, except of Ca and Mg. The required carbon sources for spikes and flowers are provided from leaves. 1.3. Spikes The natural color for spikes is green. Its structure contained chlorophyll and have the photosynthesis ability same as that of leaves and roots. However, the assimilation materials are not enough for the development of spikes and blossoms. So the required dry matter of spikes and blossoms is provided by leaves. The priority of dry matter distribution for Phalaenopsis is different with other plants. Roots are the first one to obtain the dry matter. The ranking of dry matter distribution is: roots>leaves>spikes>blossoms. 2. The coexistence for vegetable and reproductive phase Most of the orchids have vegetative stage and reproductive stage. The plants at the vegetative stage are in the state of growing and developing. The plants at the reproductive stage are in the state of spiking and flowering. The distinction between two stages is so obvious for many orchids. Oncidium is a typical orchids. At the vegetative stage, the dry matter are produced and stored in pseudobulbs. At the reproductive stage, the leaves stop the photosynthesis function. The required nutrients of spikes and blossoms are taken from pseudobulbs. Phalaenopsis has its special characteristics for vegetative and reproductive stages. As plants develop from tissue culture plantlets to reach the mature stage, it is in the vegetative stage. As these mature plant are moved to cooling environment for spiking and, it is in the reproductive stage until the length of spikes is reached to 3-5 cm. However, two stages are coexistence at the flowering phase. The spikes are lengthened continuously and buds are appeared (reproductive stage). The leaves 2
accumulated dry matters and send them to spikes and blossoms (vegetative stage). That is, the required dry matters 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 so important at the flowering stage. The leaves must be maintained in the optimum day and night temperature. The light intensity and period are also important. The nutrients need to be supplied correctly. So the leaves can accumulated enough dry matters and send it to spikes and flowers to ensure the flower quality. 3. The factors affecting the Phalaenopsis quality 3.1. Genotype The genotype characteristics of the Phalaenopsis variety includes flower color, pattern, flower size, flower numbers, numbers of spikes, multi or no branch, and stem height, et al,. 3.2. Health conditions The plant must maturity enough before to be sent to cooling room. It must store enough dry matters in plants. The plants required no disease, no pest damage, virus-free, no chemical damage, no salt accumulation in substrate. 3
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 optimum range. The interaction of genotype, health conditions and environment needs to be emphasized. The genotype decides the maximum possible for the expression of flower quality. For example, the genotype of flower numbers for the little white flower, P. amabilis, is more than twenty. If the plant is mature enough and the cooling environment is kept at good conditions, the grower will obtain more than twenty flowers for each plant. However, the number of flower will decrease as the plant is immature, or damage by disease or pest, or the temperature or light intensity do not maintain well. The effect of microclimate on other flower qualities was described as follows: 4
3.2.1. The temperature difference of vegetative stage and cooling stage The numbers of spike is affected significant by the temperature difference between vegetative phase and cooling phase. The "Mansanfong" variety is used to illustrate the effect of the temperature difference on the number of spikes. The adequate day and night temperature for vegetative stage is 28 and 26. If the cooling temperature of day and night is kept at 25 and 20, these plants have 100 % of the single spike. As the cooling temperature of day and night is maintained at 23 and 20, these plants have 40% of the two spikes and 60% of the single spike. At the environment of 20 day temperature and 18 night temperature, these plants have 100% of the two spikes. 3.2.2. The difference between day and night temperature at flowering stage The symbol of DT represents the difference between day and night temperature at flowering stage. As DT increase, the length of spikes (or stems) is lengthened. As DT decrease, the length of spikes (or stems) is shortened. Figure 2. DT increase, the length of spikes is too long 5
3.2.3. The day temperature at flowering stage If the day temperature at flowering stage is same or higher than that of vegetative stage, leaf will appear in the stem. It is called as Keiki s. In spite of the day temperature did not higher than the temperature of vegetative stage, but it still higher than the normal condition, the high day temperature 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 6
Figure 4. All buds will be blocked up in the end of stem because the day temperature is too high 3.2.4. The night temperature at flowering stage. If the night temperature at flowering stage is higher than the adequate condition, the number of blossoms is decreased and the flower size is reduced. 4. The diversity characteristics of Phalaenopsis varieties. The required qualities are two or more spikes, multi-branching, bright color, and 40-75cm height in the Holland. According to the Culture Guide of Floricultura b.v., the adequate environment conditions for Phalaenopsis are listed as following: Table 1. The adequate environment conditions for Phalaenopsis day temp night temp light intensity Vegetative phase 28 26 4000-6000lux 7
Cooling 20 18 7000-8000 lux Flowering phase 23 20 7000-8000 lux However, the growers usually found that many varieties could not produce the required quality according to these environment conditions. In the orchids greenhouse, leaves colour of some varieties was found that turned into red and dark (Figure 5) in the Holland. Some varieties still be induced to spike at the growing regions (day temp. 28, night temp. 26 ) (Figure 6). Some varieties can not be induced 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 8
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. 20, night temp.18 ) 9
5. The classification of the Phalaenopsis characteristics 5.1.According to the culture temperature There are seven types of Phalaenopsis varieties classified by its optimum day and night temperature in 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 10
at Pingtung County, southern Taiwan. The 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. Larger and beautiful blossoms are founded in this plant. Figure 8. The beauty blossoms of three spikes for V3, P. Sogo Yukidian Some plants were transported to the New York State, USA. The microclimate in that greenhouse for the growing stage was set at 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. As the greenhouse temperature was decreased with the season change and the spikes were induced. The quality of spikes and blossoms 11
can not correspond to the market requirement (Figure 9) 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. That is the reason that many varieties of Phalaenopsis have been send to the Holland. Some varieties had the excellent flowering quality. However, many varieties did not appear the accepted quality. 6. The selection of the adequate varieties for the Holland 6.1. The greenhouse microclimate The microclimate of greenhouse for Phalaenopsis in the Holland is listed in the Table 1. The day and night temperature are 28 and 26 for the vegetative stage. The day and night temperature are 20 and 18 for cooling phase. So the 12
selection 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. The required of variety for the Holland The basic requirements of variety are the genotype and plantlet conditions The genotype and others conditions of adequate varieties is listed as follows. A. double or more spikes B. medium or large size of blossoms, at least 8 cm C. the number of flowers is 6 at least for each spike D. bright color of blossoms E. compact size, more plants can be placed per square meter F. others, the plant conditions of plantlets are no disease, no insect damage, virus-free, no chemicals damage, no salt accumulation in substrate. The leaves and roots are kept at 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: bse.nchu.edu.tw Email: ccchen@dragon.nchu.edu.tw 13