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Spiking inhibition technique of Phalaenopsis

 
 

The purpose of the spiking inhibition technique of Phalaenopsis is to prevent these plants from vegetable phase to reproductive phase. It is an important technique for the Phalaenopsis industry.

Recently, more orchids growers like to purchase the mature plants of Phalaenopsis so the turnover could be reduced. The higher temperature and relative humility in Taiwan provide the opportunity for the faster growing of orchids. However, the winter weather enhanced the spiking of Phalaenopsis. As the spiking was induced in the young stage, the quality of orchids would be decreased. In order to supply the mature Phalaenopsis plants for the overseas market, the spiking inhibition technique need to be understood for growers.

As the factors that influence Phalaenopsis spiking induction are understood, the spiking inhibition technique is easy to be conducted. However, the difficult of the technique for growers is to inhibit spiking of Phalaenopsis and to keep these plants grow. That is, the inhibition technique can not interrupt the growing stage of plants.

The basic requirements of spike inhibition technique are introduced as follows:

1.      This method must be simple, efficiency and economical.

2.      The inhibition period and the spiking period might be connected. As the growers finish the inhibition operation, the inducing process could be conducted continuously.

3.      The quantity and quality of orchids could not be damaged by the inhibition operations. In the inhibition processing, the plants need to maintain in the healthy conditions.

4.      The growing schedule of orchids did not be interrupt by the inhibition operation. If the orchids cease growing in the inhibition phase, the greenhouse space was limited and energy consumption is lost. The reasonable technique of inhibition is to keep the plants growing and to prevent it from changing it to reproductive stage.

The requirement factors of the inducing spikes for the Phalaenopsis are listed as follows:

1.      The maturity.

2.      The environmental factors, such as temperature, light intensity and light period.

3.      The management, such as watering, fertilization and hormones applying.

 

The inhibition operation could be developed by considering on the contrary way of spikes inducing.

1.     Avoiding the stress

The abnormal stress included the drought treatment and root injuring. These factors could enhance the spiking. However, the plant was damaged and the flower quality is poor. Both factors can be avoided by the training of labors. The other abnormal stress was inducted by the interrupt change of greenhouse temperature. For example, the outsize cold air was sucked into greenhouse by the improper control strategy. This case could be improved easily.

2.     Chemicals application

Some special chemicals had been applied by the growers to prevent the orchids from spiking. The principle of the chemical application was to decrease the C/N ratio, or retard the formation of GA or BA hormone. Some secret chemicals had indeed the ability to retard or prevent the N adsorption. These chemical are useful to prevent spiking. However, as the growers wanted to cease the inhibition and transform plants to the inducing phase, it required a longer period to dilute the concentrations of chemicals in the plants. This technique is impractical for orchids industry.

3.     Environmental control

By the environmental control technique, growers could control the change of the day and night temperature, light period and quantity of the greenhouse. The purpose of this technique is to change the C/N ratio or maintain at higher temperature. The higher C/N ratio is helpful for spiking. On the contrary, the decrease of the C/N ratio could be benefit for the inhibition. The cold temperature stress induces spiking and so the maintain of higher greenhouse temperature could prevent the spiking.

(1)       Reduce the carbon source

Reducing the carbon source is useful for the inhibition. The carbon of orchids is obtained by the photosynthesis. The influencing factors are light, temperature and water. Recently, some inhibition techniques are developed by considering of these factors. The full dark cloth treatment (no light source) could inhibit the spiking because of the lack of energy source for Phalaenopsis. Some growers applied the treatments of five day’s dark period and two day’s light period to help the inhibition of the spiking. However, the most difficult parameter for this technique is how to determine the accumulation light quantity. This technique required the precision measurement of light quantity and the full acknowledge of the required minimum light quantity of orchids.

(2)       Change the setting of day and night temperature.

To maintain the day and night temperature at the optimum level is the most effective way to inhibit the spiking and let the plants keep growing. For example, the 24℃ day temperature and 20℃ night temperature is the critical temperature for growing and preventing spiking of the amabilis variety. The 28℃ day temperature and 24℃ night temperature is the critical temperature for the V3 large White Phalaenopsis.

 

Why the energy cost is so high for preventing spiking? The reason is simple. The setting temperatures of day and night in the greenhouse were so high. According to the Culture Guide of Phalaenopsis for Floricultural b.v. and Anthura b.v., the setting temperature of growing phase are 28 and 26 for day and night temperature. This critical temperature is correct for the selected varieties of both companies. The required heating energy was higher than that of the other crops.  However, the critical values of this inhibition temperature are not the standard value for all Phalaenopsis varieties. Many varieties would lose their quality and vitality in this temperature range.

The energy cost for the heating is determined by the structure and covering films of greenhouse, the outside air conditions, heating equipments and the setting temperature of greenhouse. The effective way to inhibit the spiking and maintain the growth of plants is to maintain the optimum conditions of plants. The optimum conditions of each variety include the aerial environment (temperature, light, relative humidity, et al.) and root environment (water content, fertilizing management, et al.).

 

The reasonable techniques of spiking inhibition are:

1.      To know the physiological characteristics of varieties.

2.      According the production plants, selected the adequate varieties by their requirement temperature.

3.      Maintain the day and night temperature of greenhouse according to the required condition of these varieties.

        The adequate variety for the inhibition spiking easily and energy serving is the variety that required higher day temperature (ex. 28-33℃) and lower temperature (ex. 22-24℃) for growing. The day temperature is easy to be increase by the solar energy. This is the cheapest energy for orchids industry. The heating energy at night is the expensive cost for orchids production. Maintain the optimum night temperature to inhibit the spiking and maintain the growth of plants is the best way for the inhibition spiking technique.

 

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