[Adaptive changes of photosynthesis at a raised carbon dioxide concentration]
2008
Kosobryukhov, A.A.
The main test object is cucumber plants (Cucumis sativus) of the hybrid Moskovskij teplichnij. Other crops have been used in a number of the experiments. A reaction of the plant photosynthetic mechanism (PM) to long-term and short-term increase of carbon dioxide (CD) concentration is studied. The plant response to a long-term (during a day and a vegetative period) increase of CD expresses in dry matter gain, its translocation into stems and roots, leaf area extension and photosynthesis speed growth at relative decrease of breathe cost. Adaptive PM transformations stipulate decrease of positive CD effect at long-term action against the background of a high light intensity. They display in pigment content decrease, more intensive accumulation of starch and soluble carbohydrates in leaves, speed changes of light photosynthetic reactions and carboxylation decrease. A short-term CD growth (by some hours) increases photosynthesis speed, but its effectiveness depends on a light regime. A positive effect of periodical light changes on PM activity develops during some hours coming to plateu after 4-6 hours. This technique can be used for plant productivity increase without energy costs. The same dynamics of photochemical and biochemical reactions is observed at stress factors (sulphur dioxide, ultra-violet irradiation, methanol treatment of leaves) as at light and temperature changes. Probably, adaptive mechanisms at plant cell and organism levels start to act in all these cases.
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