10/10/2023 0 Comments High light![]() Medium-light intensity does not produce as good results as high-light intensity but it can still result in an increase in plant growth (fresh weight), and 77% of orchids bloom. Nearly all (98%) of the orchids under the high light treatment produced flowers. High PPFD resulted in the highest increase in fresh weight of roots and leaves, earlier flowering, more and bigger blooms than medium or low PPF. The experiment was done over a year at a greenhouse using a shade cloth to keep only 12% (for high light PPFD), 5.4% (medium light PPFD) and 2.6% (low light PPFD) of the sunlight (which is ranging from 1700 to 2300 umol/m2/s from summer to winter). This is based on the experiment findings by Konow & Wang (2001). However, their optimal light for development and blooming is 100 umol/m2/s. Some orchid species such as Phalaenopsis, Jewel orchids can tolerate low light, as low as 46 umol/m2/s. a longer period of time) for the intake of carbon dioxide. This level of lighting promotes photosynthetic activities as it allows the leaf stomata to open fully during the whole night (i.e. The optimal light intensity for all types of orchids is 100-500 umol/m2/s. Related: Why “umol/m2/s” (PPFD) is The Best Metric to Measure Light Intensity for Growing Plants ![]() (Click here to learn more about stomata opening in orchids).Īccording to a study of Dendrobium orchids, a light intensity of PPFD 1000 umol/m2/s and above inhibited the aperture of stomata during nighttime and allowed for a full opening only for a short period of time after dawn (Su & Zhang, 2003).Ĭattleyas can tolerate a higher light intensity and will only suffer from photo-inhibition with an intensity of 1650 umol/m2/s or above (Stancato, Mazzafera & Buckeridge, 2002). Orchids are supposed to open their stomata during night time and during the early morning hours which are supposed to only close when it gets bright and hot in the day. (But many orchid species can be trained to acclimatize to very strong light, even the full sun, and would even thrive under very strong light) Related: How adjusting light intensity and temperature can trigger blooming in orchidsĮxposing orchids to too much light not only would result in sunburnt leaves, but more importantly stunted growth as it would affect photosynthesis by inhibiting the opening of stomata on the undersides of leaves, which are responsible for the intake of carbon dioxide. and even leaf drop under very low light conditions below 50 umol/m2/s after 6 weeks (Wang, 1995 Kubota & Yoneda, 1993).And a continuous supply of sugar to the apex of a reproductive bud is essential for floral development. An increase in light intensity helps blooming because light helps the photosynthetic production of sugar. Orchids under a higher light intensity (100 – 120 umol/m2/s) performed slightly better but produced only half the quantity of flowers which were smaller in size than orchids under a higher light intensity (200 – 280 umol/m2/s). lack of blooming (only 2% of the orchids bloomed in low-light situations).shorter, narrower, fewer and thinner leaves, and smaller total leaf area and fewer roots.slow growth of orchid seedlings in-vitro, with smaller plants and longer production time.below 100 umol/s/m2, or 2.6% of full sunlight) resulted in: With too little light, the health of orchids will suffer and they will have problems with spiking and flowering.Īccording to a study (Konow & Wang 2001), low light intensity (i.e. But, this does not mean that orchids can thrive in darkness. Orchids are adapted to low light conditions as they are adapted to living under the canopy of trees in rainforests. Conclusion Orchid Light Requirement Chart 1.How To Tell If An Orchid Has Too Little Or Too Much Light?
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