Effect of Phenological Stage and Leaf Age on Changes of Chlorophyll and Carotenoid Contents in Some Weeds and Invasive Species

Potential sources of chlorophyll, widely used in the pharmaceutical and food industries, could be invasive species and weeds. The aim of the study was to estimate the effect of vegetation period and leaf age on changes of chlorophyll and carotenoid contents in leaves of six widespread plant species of four different families, as well as in the weed <i>Urtica dioica</i> as a "comparative" species. Plants were growing under the same environmental conditions, and chlorophylls and carotenoids were analyzed spectrophotometrically every two weeks from May to September. Average total chlorophyll (<i>a</i> + <i>b</i>) content only in leaves of <i>Lamium album</i> and <i>Aegopodium podagraria</i> was lower than in <i>Urtica dioica</i> and significantly differed from their content in <i>Leonurus cardiaca</i> and <i>Agrimonia eupatoria</i>. Total chlorophyll (<i>a</i> + <i>b</i>) content in leaves of common native <i>Pastinaca sativa</i> and very invasive <i>Solidago canadensis</i> was also higher or very similar to that of <i>Urtica dioica</i>. The highest amount of green pigments in all species was found at the budding and/or flowering period. Unlike other species, variation of total chlorophyll (<i>a</i> + <i>b</i>) in <i>Leonurus cardiaca</i> was little, and chlorophyll <i>a</i>/<i>b</i> ratio was lower than 2:1 during the vegetation period. In contrast to total chlorophyll (<i>a</i> + <i>b</i>), total carotenoid was higher in young leaves.