Fine-root traits of allelopathic rice at the seedling stage and their relationship with allelopathic potential

Abstract

Background Allelopathic rice releases allelochemicals through its root systems, thereby exerting a negative effect on paddy weeds. This research aimed to evaluate the relationship between fine-root traits and the rice allelopathic potential at the seedling stage. Methods Two allelopathic rice cultivars, ‘PI312777’ and ‘Taichung Native1,’ and one non-allelopathic rice cultivar, ‘Lemont,’ were grown to the 3–6 leaf stage in a hydroponic system. Their fine roots were collected for morphological trait (root length, root surface area, root volume, and root tips number) in smaller diameter cutoffs and proliferative trait (root biomass) analysis. Their root-exudates were used for quantitative analysis of phenolic acids contents and an evaluation of allelopathic potential. Correlation analysis was also used to assess whether any linear relationships existed. Results Our results showed that allelopathic rice cultivars had significantly higher fine-root length having diameters <0.2 mm, more root tips number, and greater root biomass, coupled with higher allelopathic potential and phenolic acid contents of their root exudates, comparing with non-allelopathic rice cultivar. These fine-root traits were significantly-positively correlated to allelopathic inhibition and total phenolic contents in rice root-exudates. However, there were not significant correlations among the rice allelopathic potential and total phenolic acid contents of rice root-exudates with the root length, root surface area, and root volume of fine root in diameter >0.2 mm. Discussion Our results implied that fine-root traits appears to be important in understanding rice allelopathy at the seedling stage. The high allelopathic potential of rice cultivars might be attributed to their higher length of fine roots <0.2 mm in diameter and more number of root tips of fine root, which could accumulate and release more allelochemicals to solutions, thereby resulting in high inhibition on target plants. The mechanisms regulating this process need to be further studied.

Phytotoxic Activity of Melia Azedarach(l.) Aqueous Leaf Extracts on Germination and Seedling Development of Abelmoschus Esculantus (L.) and Sesamum Indicum (L.)

“…Secondary metabolites, also known as allelochemicals, are released to induce effect [2][3][4] . Allelochemicals induce unfavorable physiological effects in neighboring plants, such as inhibiting the percentage and speed of germination and reducing the initial growth of seedlings 5 . Allelochemicals are natural phytotoxins that, as an alternative to commercial herbicides, can manage weeds in sustainable agro-ecosystems.…”

RgC3H Involves in the Biosynthesis of Allelopathic Phenolic Acids and Alters Their Release Amount in Rehmannia glutinosa Roots

“…A growing body of evidence suggests that autotoxic harm to plants mediated by root exudates plays a crucial role in replanting disease [3,6,9,10]. Some endogenous phenolic acids, which are important root exudates, are involved in allelopathy and are prone to directly or indirectly cause autotoxicity, resulting in replanting disease in some plants [6,[11][12][13]. Several phenolic acids (e.g., ferulic acid (FA), caffeic acid (CA) and chlorogenic acid (CHA)) have been identified as allelopathic autotoxic agents in R. glutinosa and other plants [3,6,13].…”

“…Some endogenous phenolic acids, which are important root exudates, are involved in allelopathy and are prone to directly or indirectly cause autotoxicity, resulting in replanting disease in some plants [6,[11][12][13]. Several phenolic acids (e.g., ferulic acid (FA), caffeic acid (CA) and chlorogenic acid (CHA)) have been identified as allelopathic autotoxic agents in R. glutinosa and other plants [3,6,13]. These phenolic acids are mostly phenylpropanoid products of secondary metabolism in plants [3,[13][14][15].…”

“…Several phenolic acids (e.g., ferulic acid (FA), caffeic acid (CA) and chlorogenic acid (CHA)) have been identified as allelopathic autotoxic agents in R. glutinosa and other plants [3,6,13]. These phenolic acids are mostly phenylpropanoid products of secondary metabolism in plants [3,[13][14][15]. A thorough understanding of the biosynthesis and release of these allelopathic phenolic acids and the characterization of the enzymes involved are important for elucidating the underlying mechanisms of the development of replanting disease, especially in the case of the production of the medicinal plant parts (roots) of R. glutinosa.…”

Allelopathy of the Melia azedarach L. Leaf Extract on the Germination of Three Selected Atlantic Forest Species

“…The production of chemical compounds or allelochemicals can cause damage to the development of biological systems [2]. The allelochemicals exert ecological mechanisms in the adjacent plants, usually because they cause negative physiological effects such as the inhibition of the percentage and speed of the germination and the reduction of the initial growth of seedlings [3,4].…”