Study On Osmotic Adjustment And Adaptation In Two Kinds Of Duckweed Under PEG-6000 Stress

In this paper, we treated two kinds of duckweed with PEG-6000, choose the duckweed growing in normal environment as the control, and studied their damage rate, death rate, content of organic osmotic substance and inorganic ion, cell membrane permeability, the results showed that the drought tolerance ability of two kinds of duckweed was: Spirodela > Lemna minor:(1) Under the same treatment, the damage rate and death rate of Lemna minor was higher than that of Spirodela.(2) The relative content of organic osmoregulation substance were all significantly increased, the dehydration and significant collapse of the cell was the main reason.(3) The increase of relative content of MDA in Lemna minor was higher than that in Spirodela, the damage degree was more serious than Spirodela. After stress, the trend of the cell membrane permeability of the two kinds of duckweed appeared rise first and then fall.(4) After dehydration stress, the relative content of 4 kinds of inorganic ion were all significantly increased, the relative contents of K+、Mg2+and Ca2+ showed Lemna minor > Spirodela, except Na+.(5) During the stress time, the absolute content of proline, betaine, mannitol and Ca2+ in two kinds of duckweed increased.(6) The results of the principal component analysis showed the main factor of the two kinds of duckweed were MDA, Ca, cell membrane permeability, soluble protein, Na, and proline. We found that the rank of ability of drought resistance stressing was Spirodela > Lemna minor.(7) The result of subordinate function analysis showed that the sequence of comprehensive evaluation of two kinds of duckweed in the different concentrations of PEG stress was Spirodela > Lemna minor. It was the same with the results of the principal component analysis.(8) The resistance of duckweed was rely on its resistance capacity of collapse and transformation and capacity of maintain the integrity of the cell membrane.