Effect of Sunlight Intensity Against Orchid Growth (ORCHIDACEAE)

INTRODUCTION

Orchid plants in scientific terms is called Orchidaceae and has approximately 700 genera that includes some 20,000 species and there is even a suspect to 35,000 species in Indonesia was reported there are approximately 5000 species of Van Steenis cit Sutarni MS (19).
Orchid liked by his fans because of the beautiful flower colors varied from yellow, green, blue, violet, purple, red peppers, copper brown, brick red, fragrant flowers and the flowers because they last longer, for the moon orchid (Phalaenopsis) between 1 up to 5 months (Ayub S.P, 1984)

Indonesia may, planting all kinds of orchids from around the world, ranging from tropical climates to sub-tropical climate (Ayub S.P, 1984).
To obtain optimal growth and diligent orchids blooming orchid plants then environmental conditions must be in optimum condition. Environmental factors that affect the growth of orchids by Moeso Suryowinota (1988) suggests that there are two factors: macro factors and micro factors.
Macro factors include:
1. sunshine
2. The air temperature
3. humidity
4. cloud
5. wind
6. O2 and CO2 air
7. air pollution

And micro factors (factors edatif) of growth media which include: nutrients, texture, structure of the media, the composition of the solution, and air composition of O2 and CO2 in particular media.
In this paper the author will suggest the macro factor is the influence of solar light intensity of sunlight on the growth of orchids (Orchidaceae).

ORCHID AND NEEDS THE SUNLIGHT
Orchid for absolute life will require sunlight. Needs of orchids on the intensity of sunlight varies depending on the type, there is a need sunlight that much, but there is also the type that requires only a little.

According to Simon & Schusters (19) suggests that the orchid Dendrobium requires full sunlight (full sun) was labiata Cattleya, Cymbidium sp., Cypridium calceolus, and Phalaenopsis sp need some sunlight in the shade (semishade).
According S.M. Latif (1960) suggested that for Arachnis orchid (orchid spiders = scorpion) can be grown in soil and in the heat of direct sunlight (full sun), to the high mountains of the origin of life is good enough solar heat gain. Dendrobium orchids require nearly all the heat and get hot in the daytime. Paphiopedilum orchids grow their natural habitat are protected under the tree. Phalaenopsis orchids like all kinds of light. And Vanda orchids are planted in a hot place.
According to Yos Sutiyono (19) suggests that the orchids Cattleya, Oncidium, Vanda generally live a shaded place. Should terete Vanda orchids (Vanda pencils), Arachnis, Aranda, Renanthera, Renanthanda, and Aeridachnis require sunlight in greater numbers.
According to Sugeng Sri Lestari (1985) suggests that Phalaenopsis orchids require plenty of sun but also requires a rather moist places, especially it only requires a little light that is directly about it. Cattleya orchids like bright sunlight, but can not receive full sunlight, maximum 60% can receive sunlight on the plants mature. And Vanda Teres orchids are planted on the ground in places exposed to full sunlight and is also resistant to sunburn.
According Susiani Purbaningsih (1988) suggested that the orchid community pots (nursery) are not exposed to direct sunlight and needs ranging from 800-1500 fc
According Moeso Suryowinoto (1988) argued that the needs of species of orchids to the sun varies by type:
The intensity of light orchid species:
* Paphiopedilum 10 – 15 %
* Aerides 15 – 30 %
* Vanda 20 - 30 %
* Phalaenopsis 10 – 40 %
* Cattlleya 20 – 40 %
* Dendrobium 50 – 65 %
* Oncidium 60 - 75 %

And an outline of the criteria distinguished sunlight shines into four groups:
1. Strong beam, means full sun or 100% no barrier / shade, this is in the tropics.
2. Somewhat shady, sunlight intensity 50-100%. The presence of shade, if a curtain is still there between for the entry of sufficient light. Shade trees usually in the form of a tree having compound leaves are thin like: Flamboyant, sengon, petai, petai china, acid, pine and others.
3. Half shade, intensity of light that makes the state a half shade illustrate the condition of the incoming sunlight by 50%. Usually used curtain fabric, clear plastic paint sprayed white milk, bamboo blinds can also be used.
4. Completely calm, a state where direct sunlight is not accepted by the plant, but the beam is obtained from the diffraction / diffuse emission. here intensity
sunlight of magnitude less than 5%.

Based on the ecology of receiving light, plants are classified as follows:
1. Heliofit, ie plants that grow well in full sun if shining.
2. Skiofit, ie plants that grow well in lower light intensity.

Thus the group of orchids including skiofit heliofit well depending on the type orchid. Skiofit helioffit different in its ability to increase levels of chlorophyll at low light intensities. Skiofit possibility can not form chlorophyll rapidly, if the plants are exposed to full sunlight. Continuous light would damage chlorophyll (Daubenmire, 1959), so that would preclude fotosistesis (Bjorkman, 1968); Holmgren, 1968, sit Leopold & Kriedemann, 1975).
Generally, the light intensity was varied each day (Edmond et al, 1957). In addition the needs of different light intensities on each species (Weaver & Clements, 1966).

ORCHID GROWTH AND INTENSITY OF SUNLIGHT
Sunlight is the main source of energy for life, without the sun life would not exist (Pearse, 1939 sets of Wilsie, 1962).
For plant growth in addition to the influence of light was determined by its quality was determined intensity (Day Suseno, 1976).
Light intensity significantly influenced the nature of plant morphology. Plants that get sun light with high intensity causes the girth grows faster, more perfect composition of wooden vessels, internodia shorter, thicker leaves, but smaller in size compared with protected plants (Wilsie, 1962). Some of the effect of full sunlight (in excess) can cause wilting optimum needs, fotosistesis slow, respiration rate increases but it tends to enhance the durability of the plant.
High light intensity in the tropics is not fully used by plants (Curtis & Clark, 1950, Suseno, 1974). Solar light energy is used by plants in the process of photosynthesis ranged between 0.5 to 2.0% of the total available energy. So the result of photosynthesis is reduced when the light intensity of less than optimum limit required by plants, which depend on the type of plants (Leopold & Kriedemann, 1975) this also applies to other types of orchids.
Provision of shade on the plant both natural & artificial, would mean reducing the intensity of light received by plants, this will mempengruhi growth and crop yields (Daubenmire, 1962).
Plants that get less sunlight will have a short root, this is reinforced by the opinion of Shirley sit Wilsie (1962) that the full sunlight produces roots are longer and more branched. So also reinforced by Yos Sutiyoso (19) states that orchids enough sunlight will develop better rooting, number of roots will be a lot, big size and much branched. Root out early, so not far from the top of the plant species monopodial orchids such as Vanda, Arachnis.
When sunlight is less, because orchids are in a state too shady, then the process of assimilation will be reduced, so the carbohydrate as a result of the process is also less in number.
Carbohydrate will be transported through the filter vessel and the roots in respiration to produce energy. If the plant can produce less carbohydrate energy is then generated only slightly, while the energy necessary for roots to absorb water and nutrients following push into other plant parts. If the plant can produce less carbohydrate energy is then generated only slightly, while the energy necessary for roots to absorb water and nutrients following push into other plant parts.
In the shade of orchid plant cells are formed by large cells, but deflated, because the watery protoplasm in plant cells. Plants will be a long segment of a plant to catch the sun quickly, orchid plants look pale and weak. Plants will be easier to evaporate the water because the cuticle / wax coating on the leaf surface is very thin (Joshua Sutiyoso, 19)
According to Smit (1975) suggests that the influence of the most common morfogenik of growth in the dark (very low light intensity) is a growth segment (internodia) becomes very slow and the development of the leaves become depressed are weak and pale.
According to Jos Sutiyoso (19) that the light of the sun with his assimilation will lead to carbohydrate at one time reached the threshold value which is the stimulus for flowering orchid plants. With excessive shade, then the value of this threshold will not be achieved, so the interest was not generated. Many owners complain that the plants orchid plants have been maintained for years seriously, but do not produce flowers with satisfactorily.
Besides, the intensity of sunlight affects the quality of the flowers. The intensity of light is less bright as the color of the flowers are not flowers enough sunlight. Texture / thickness so that the interest rate is not how easily and quickly wilt fall (Yos Sutiyoso, 19).
According to Williams et al, (1976) suggested that the reduction of light from a plant that has optimum light, temperature and the moisture it will cause the reduction of root growth and plant shows symptoms etiolasi.
Daniel et al, (1979) explains that the process of photosynthesis, light is affected by the intensity, quality and duration of irradiation, but most of its intensity. This is supported by Soekkotjo (1977) explains that the light intensity effect on the enlargement and cell differentiation.
In connection with fotosisntesis rate, the higher light intensities (up) and resulted in increasingly fotosisntesis not increase again, although the intensity of the light continues to grow. This limit is called the saturation point of light or light saturation point (ligh saturation point). In light of this situation not as a source of energy as well as form, but as a destroyer (destructive photo).
High light intensity resulted in increased leaf temperature, as a result of the stomata closed, so in part chlorophyll to be broken and damaged (fotodestruktif).
Kramerdan According to Kozlowski (1979) explains that the rate of photosynthesis is caused by rising temperatures which resulted in the closure of leaf stomata and the destruction of chlorophyll, so that the concentration of chlorophyll is reduced.
While the intensity of light that gradually deteriorated to a certain extent the amount of O2 released by the process of photosynthesis equals the number of O2 required by the process of respiration. This limit is called the light compensation point (light compensation point).
Therefore each type of plant and also any type of orchid has a limit point of light compensation and light saturation point is not the same.
Orchid plants that receive the light above the optimal light intensity showed thicker leaves with a smaller amount of chlorophyll. This is in accordance with the opinion and Kozlowneski Kramer (1979) that the chlorophyll content of plants in the shade of larger per unit of dry weight compared with plants that are open, mampunyai leaves are thicker, so that a greater volume per unit area.
Orchid plants that received light intensity of the higher expected number of leaves the less, it is consistent with the results of research by M. Mochtar Effendy (1987) that the light intensity significantly influenced the number of leaves and seeds of Shorea leprosula Shreaacuminatissima. The higher the intensity of light that shows the smaller the number of leaves. The number of leaves of seedlings with maximum intensity is achieved in approximately 50% of full light. And showed that the number of leaf chlorophyll have a tendency to
decreased with increasing light intensity.
The number of leaf chlorophyll closely associated with fotosisntesis process, because it will directly affect the rate of fotosintesiss. The rate of photosynthesis showed an increase with increasing light intensity (Williams and Yoseph, 1976), but the rate of photosynthesis will decrease after passing the light saturation point.

CONCLUSION
From the above literature review it can be deduced as follows:

1. Each type of orchid requires a light intensity varying.
2. Optimal growth of orchids, one factor is given when the light intensity mahatari needs optimally.
3. The intensity of sunlight that exceeds the optimal needs of orchid plants, causing stunted growth, smaller leaf size, leaf chlorophyll will become damaged, then the leaves become yellowish = chlorosis, and increased leaf burning symptoms.
4. The intensity of sunlight that is lower than the optimal needs of orchids will show that leaves no thicker, greener leaves, roots is reduced, a longer segment (etiolasi symptom), diminished interest and color of the flowers are not bright.

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