Anthocynins are flavonoid molecular pigments in plants. They are water soluble and appear red to blue shades. The colour of these pigments depends on various factors such as light, temperature, nitrates etc.
Anthocynins reflects red and blue light and absorb UV-B. More light can also lead the plant for death so they produce anthocynins to protect from the ill effects of intensity of light.
2. We need to increase the production of anthocynin and decrease the production of chlorophyll for more redness. By reducing some type of intensity of light wavelength and other nutrients, plants can be come in stress and in result, plants will produce more redness in leaves.
3. Iron dosing is not responsible for red colouration in aquatic plants. Although, it helps in increasing the rate of photosynthesis. Plants are not able to control the rate of photosynthesis but they can increase the amount of anthocynins. They adept themselves by changing pigments from chlorophyll to anthocynins.
4. High amount of Nitrate enhance the growth of plants but reduce the production of anthocynins. To maintain redness in plants, Nitrate level should be low.
5. High pH increases the production of anthocynins. If aquarium water having high nitrate level, pH level will be drop. Plants growth will be enhance due to reduced production of anthocynins.
Note: After reading lots of, I am publishing above lines. I have gain all the information from Internet and compile in my own words.
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