Impact of allelochemical exuded from allelopathic rice on soil microbial community

Plant-borne flavonoids released into the rhizosphere: impact on soil bio-activities related to plant nutrition. A review

“…Likewise, the flavones hyperoside and galangin inhibited hyphal growth of various phytopathogenic fungi (Afolayan and Meyer 1997;Li et al 2005). A reduction in abundance in cultivable fungi in both rhizosphere and nonrhizosphere soils was observed after tricin exudation from roots of allelopathic rice seedlings (Kong et al 2008). Apart from growth inhibition, spore germination appears to be a developmental process which is readily stimulated or inhibited by a wide range of different flavonoids (see below), although most of evidence for this particular process might originate from its easy determination rather than from a truly preferential target for root-borne flavonoids.…”

“…For example, 4′,6,7-trihydroxy-3′,5′-dimethoxyflavone inhibited the growth of Trichoderma viride (Zheng et al 1996). This compound was purified from shoots of Artemisia giraldii (Zheng et al 1996), but it is chemically similar to the root-exuded compound tricin (Kong et al 2008). Aspergillus flavus was inhibited by 3,5,7-trihydroxyflavone, as was Cladosporium herbarum, albeit at higher concentrations (0.05 mg ml (Chabot et al 1992) Flavanones Naringenin 5,7,4′-Trihydroxyflavanone…”

Effects of two root-secreted phenolic compounds from a subalpine coniferous species on soil enzyme activity and microbial biomass

“…[1,2] These C compounds can be divided into two classes: (i) low-molecular weight compounds such as sugars, amino acids, organic acids, phenolics, and other secondary metabolites, which are responsible for much of the root exudate diversity, whereas (ii) high-molecular weight compounds, including mucilage and proteins, which account for a large proportion of root exudates in terms of mass. [3,4] It has been known that root exudates are key mediators in belowground plant-microbe-soil interactions and functioning, involving soil microbial community and enzyme activity, soil organic matter (SOM) decomposition and nutrient cycling, and allelochemical interactions.…”

Allelopathy as protectant, defence and growth stimulants in legume cereal mixed culture systems

“…The use of allelochemicals released from plants growing in mixtures for weed management (Table 3) is one biological means of reducing the use of synthetic herbicides (Fageria & Baligar 2003;Gealy et al 2003;Khanh et al 2007;Kong et al 2008). There have been concerted efforts by researchers to use some known and unknown natural products as bio-control for weeds (Table 3), pathogens and insects, to reduce the use of chemical pesticides in mixed culture systems.…”

“…Of these compounds, flavone O-glycoside is of particular interest because as soon as it is released into the rhizosphere soil, it is rapidly transformed into aglycone 5, 7, 4-trihydroxy-3, 5-dimethoxyflavone, which effectively reduces the paddy weeds (Kong et al 2007;Gu et al 2009). For example, the reduced growth of Echinochloa crus-galli in paddy fields was attributed to allelochemicals released by the roots of rice (Fageria & Baligar 2003;Gealy et al 2003;Kato-Noguchi & Ino 2003;Kong et al 2006;Khanh et al 2007;Kong et al 2007Kong et al , 2008. In other studies, it was reported that the aqueous extract bioassay of wheat cultivars inhibited radicle elongation (19.2%Á98.7%) and seed germination (4.2%Á76.2%) of ryegrass (Lolium gidium Gaud.).…”