Abstract
Wolffia arrhiza (L.) Wimm. (Lemnaceae) as a mixotrophic plant reacts considerably weaker to used auxins with different chemical structures than typical photosynthetic vascular plants and algae especially from Chlorophyta. Among used auxin compounds, the highest stimulative activity on W. arrhiza growth and biochemical parameters which were analysed in biomass, can be attributed to phenylacetic acid (PAA), a somewhat smaller to indole-3-acetic acid (IAA) and the smallest to 2-naphthaleneacetic acid (NAA) used in optimal concentration of 10-6 M, in comparison with the control culture, devoid of exogenous auxins. The investigated auxins, especially PAA and IAA, were found to have the most powerful stimulative activity (prevailingly between the 10th and the 15th day of cultivation) on the content of reducing sugars between 127 and 169%, chlorophyll a and b from 117 to 125%, total carotenoids from 115 to 132% and net photosynthetic rate from 127 to 144% in comparison with the control culture, which was treated as 100% for reference. However, the content of water-soluble proteins as well as nucleic acids (DNA and RNA) in the biomass of W. arrhiza was less effectively stimulated, hardly from 110 to 116% when compared to the control culture (100%).
Keywords
Wolffia arrhiza; auxins; indole-3-acetic acid (IAA); phenylacetic acid (PAA); 2-naphthaleneacetic acid (NAA); proteins; reducing sugars; chlorophylls a and b; total carotenoids; net photosynthesis rate; nucleic acids (DNA and RNA)
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