The investigation results are presented of macrophyte adaptive alterations (using the example of reed mace Typha angustifolia L.) under conditions of different nitrate-nitrogen load. Chlorophyll indexes have been found to be indicators of helophyte potential productivity. Tenfold nitrate-nitrogen load (as compared with MPC) inhibits oxygen consumption by aquatic roots and stimulates its consumption by soil roots. Three-phase alteration of dark respiration intensity has been found in truncated additional roots incubated in natural water, these phases being physiological depression, reparation and stabilization. The respiration intensity alteration rate as a response to the stress factor (truncation) is higher for soil roots than for aquatic ones. Nitrogen stress accelerates the destruction of parenchyma cells in additional soil roots increasing the area of air pockets.
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