Saturday, May 23, 2009
WHY DOES CLOUD COVER RETARD PLANT GROWTH
If you live in the southeast, and more particularly Central Florida; and have been pounded by rain and constant cloud cover for the past week, you probably also have noticed little growth in your garden. The plants appear to be hibernating.
Aside from decrease light energy which slows photosynthesis and plant energy cycle, there is another factor at play: Photomorphogenisis.
Photomorphogenesis is defined as the ability of light to regulate plant growth and development, independent of photosynthesis. Internode elongation, chlorophyll development, flowering, lateral bud outgrowth, and root and shoot growth, all are regulated by light. Photomorphogenesis differs from photosynthesis in several major ways. The plant pigment responsible for light-regulated growth responses is phytochrome. Phytochrome is a colorless pigment that is in plants in very small amounts. Only the red (600 to 660 nm) and far red (700 to 740 nm) wavelengths of the electromagnetic spectrum appear to be important in the light-regulated growth of plants. The wavelengths involved in generating photosynthesis are generally broader (400 to 700 nm) and less specific. Cloud cover directly interferes with red spectral wavelengths and inhibits photomorphogenesis, therefore the plant stops growing.
Some plants such as tomatoes and cucurbits are very sensitive to cloud cover. In spite of warm temperatures and good drainage, they will seize growing if overcast persists. To make matters worse, the same overcast keeps bees in their hives; and as a result, plants which require pollination do not get pollinated properly, resulting in fruit deformation.
Unfortunately, there is not much you can do but hope for a little sunshine soon.
Aside from decrease light energy which slows photosynthesis and plant energy cycle, there is another factor at play: Photomorphogenisis.
Photomorphogenesis is defined as the ability of light to regulate plant growth and development, independent of photosynthesis. Internode elongation, chlorophyll development, flowering, lateral bud outgrowth, and root and shoot growth, all are regulated by light. Photomorphogenesis differs from photosynthesis in several major ways. The plant pigment responsible for light-regulated growth responses is phytochrome. Phytochrome is a colorless pigment that is in plants in very small amounts. Only the red (600 to 660 nm) and far red (700 to 740 nm) wavelengths of the electromagnetic spectrum appear to be important in the light-regulated growth of plants. The wavelengths involved in generating photosynthesis are generally broader (400 to 700 nm) and less specific. Cloud cover directly interferes with red spectral wavelengths and inhibits photomorphogenesis, therefore the plant stops growing.
Some plants such as tomatoes and cucurbits are very sensitive to cloud cover. In spite of warm temperatures and good drainage, they will seize growing if overcast persists. To make matters worse, the same overcast keeps bees in their hives; and as a result, plants which require pollination do not get pollinated properly, resulting in fruit deformation.
Unfortunately, there is not much you can do but hope for a little sunshine soon.
Labels: coud cover, overcast, photomorphogenesis, plant growth
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