Conyza sumatrensis allelopathy effect on Bidens pilosa (Asteraceae) seed germination

Abstract

Background: Other tools for weed management should be considered in addition to the use of herbicides. In this context, the identification and use of allelopathic compounds deserves attention.
 Question: To quantify phenolic compounds and evaluate the allelopathic potential of extracts of Conyza sumatrensis on the germination of Bidens pilosa.
 Studied species: Conyza sumatrensis (Retz.) E.Walker, Bidens pilosa L. (Asteraceae)
 Study site: Palotina, state of Paraná, Brazil.
 Methods: The aqueous extracts were prepared with shoot and root portions of C. sumatrensis in concentrations: 0, 1, 5 and 10 %. Germination and germination speed index were evaluated. The total flavonoids and phenols of the tested extracts were also quantified.
 Results: With increasing concentrations of the extracts there was an increased inhibition of germination of B. pilosa and delays in the germination process. The extracts from the shoot of C. sumatrensis had a more expressive effect on seed germination when compared to the extracts obtained from the root. At concentration of 10 %, the extract from the shoot reduced in 83 % the percentage of germination. This may be related to the higher concentration of total flavonoids and phenols found.
 Conclusion: The allelopathic potential of C. sumatrensis plants can be considered since both shoot and root extracts inhibited and/or reduced the germination of B. pilosa.

Low Doses of Cuscuta reflexa Extract Act as Natural Biostimulants to Improve the Germination Vigor, Growth, and Grain Yield of Wheat Grown under Water Stress: Photosynthetic Pigments, Antioxidative Defense Mechanisms, and Nutrient Acquisition

“…Furthermore, in the present study, it was found that Cuscuta reflexa is rich in phenolics and flavonoids that might have negatively affected the seed germination process at higher doses by restricting the activities of germination enzymes. Ferreira et al [ 81 ] reported that high concentrations of leaf and root extract of Conyza sumatrensis adversely affected the seed germination and seedling emergence of Bidens pilosa , and this decrease might be attributed to the high levels of phenolics and flavonoids in the extract. Rizzardi et al [ 82 ] reported that 6 and 8% concentration of extracts from the shoots of canola reduced the germination of Bidens sp., while Reik [ 83 ] recorded a reduction in the germination percentages of B. pilosa treated with the aqueous extracts at levels higher than 30% concentration (v/v).…”

Soybean growth and production under straw of maize, Urochloa brizantha, Conyza spp. and Digitaria insularis

“…In the present study, the amount of weed straw may not have been enough to release allelopathic compounds on soybean. While (19) it was reported a negative effect of aqueous extracts of Conyza sumatrensis (from roots and shoots) on seed germination of Bidens pilosa, with an increase due to the increased concentration of extracts, as well as a stronger effect for the root extracts. Similar to observed for D. insularis extracts on canola germination (34).…”

Bioherbicidal potential of plant species with allelopathic effects on the weed Bidens bipinnata L.

“…The RC and PT extracts reached GSI equal to zero at a concentration of 25 g L −1 and the JG extracts at 45 g L −1 . The GSI is proportional to seed vigor, indicating that higher values represent more vigorous seeds 24 . In our study, seed vigor was significantly reduced due to the interference of the phytotoxic allelochemicals contained in the extracts.…”

“…They can increase the permeability of the cell membrane, causing the spread of cell contents and increasing lipid peroxidation, causing the slow growth or death of plant tissue and inhibiting nutrient absorption from the environment, affecting the normal growth of plants 42 . Phenolic acids, specifically, can act by inducing an increase in the activity of oxidative enzymes, causing changes in membrane permeability and lignin formation and contributing to the reduction of plant root growth 24 .…”