Studies on organic acids in paddy field soils with reference to their inhibitory effects on the growth of rice plants

Effects of short chain fatty acids on radicle emergence and root growth in lettuce.

“…Exogenous application of millimolar concentrations of C5-C,, decreased germination of lettuce and both wild and domestic oats. As reported by other workers (LePoidevin, 1965;Lynch, Harper & Marshall, 1975;Rao & Mikkelsen, 1976;Reynolds, 1975;Takijima, 1964aTakijima, , 1964b, inhibition increased with inereasing chain length for the acids through Cy, beyond which it declined. It appeared that some SCFA combinations.…”

“…There, concentrations of six SCFA exceeded 11 mol m"-^ and direct application of the effluent to grassland killed growing plants, while application to bare soil prior to planting reduced subsequent growth. This effect of pre-planting treatment illustrates another aspect of the problems associated with exogenous SCFA; once formed, they tend to linger in the soil, affecting plant growth for a considerable period of time (Stevenson, 1966;Takijima, 1964a).…”

“…Recently it has been shown that certain tissues of some plants contain short chain fatty acids (SCFA) in quantities high enough to modulate dormancy and growth (Berrie et al, 1976;Berrie et al, 1979;Desai & Rao, 1957;Rao & Mikkelsen, 1976, 1977a, 1977bTakijima, 1964aTakijima, , 1964b.…”

“…This situation arises when application of plant material or manure to the soil is followed by waterlogging, thus providing both the substrate and the lowered O, tension favourable to microbial SCFA production. Since these are common practices in rice cultivation, it is not surprising that several studies have been done on SCFA formation in rice fields and their subsequent effects on rice plants (Rao & Mikkelsen, 1976, 1977a, 1977bTakijima, 1964aTakijima, , 1964b. The major SCFA produced during the decomposition of rice straw, C4, has been implicated in the 'Aki-ochi' condition of rice plants (Desai & Rao, 1957).…”

“…The major SCFA produced during the decomposition of rice straw, C4, has been implicated in the 'Aki-ochi' condition of rice plants (Desai & Rao, 1957). In general, the predominant SCFA produced from decaying plant material are C1-C4 (HoUis & Rodriguez-Kabana, 1967;Lynch et al, 1975;Rao & Mikkelsen, 1976;Takijima, 1964aTakijima, , 1964b with C, (Takijima, 1964a) occasionally present as a minor constituent.…”