Variation in Phenolic Compounds, Antioxidant Activity and Osmotica of Different Cultivars of Tagetes erecta L. at Different Growth Stages and Effect of its Leachates on Germination and Growth of Wheat (Triticum aestivum L.)

Abstract

The present investigation reports antioxidant and osmotic components of Marigold at different developmental stages and also presents influence of its leachates on germination and growth of wheat (Triticum aestivum L.) seedlings. Leaves of younger plants exhibit more phenols, tannins and flavonoids as compared to root and stem. Leaves and flowers of CV. PBG exhibited greater contents of total phenols and flavonoids in comparison to CV. PNG. Leaves and flowers had greater free amino acids and free proline as compared to stem and root. Sodium was more in roots than in stem and leaves, whereas potassium and nitrogen are greater in leaves and stem of younger plants. Leaves of CV. PBG accumulated greater contents of potassium, nitrogen and calcium in comparison to those of PNG. Activity of PAL, SOD and CAT was greater in older plants and in flowers as compared to leaves. Non-enzymatic antioxidant components like ascorbic acid and reduced glutathione also exhibited the same trend. Nevertheless, APX, GPX and GR activity was less in the older plants and more in flowers than leaves. APX and GR activity was higher in CV. PBG than CV. PNG, whereas the activity of GPX and GST was more in PNG in comparison to PBG. The two cultivars (PNG and PBG) of Tagetes erecta L., their different parts and developmental stages showed considerable variation in their antioxidant and osmotic constituents. Accumulation of various antioxidant and osmotic components reported above may probably help Tagetes erecta L. adapt to varying environments. Higher concentration of leachates of leaves and flowers of marigold reduced germination percentage and seedling growth of wheat, whereas treatments of leachates of lower concentration somewhat stimulated the growth of wheat seedlings. Flower leachates showed more pronounced effects than leaf leachates. Further experimentation may lead to identification of allelochemicals in these leachates which may pave way for exploring the possibility of their use along with synthetic herbicides/weedicides in order to minimize the toxicity of soil caused by the use of synthetic compounds.