Effects of acetic, propionic, and butyric acids on rice seedling growth and nutrition

Abstract

Soils which are flooded for lowland rice culture shift from aerobic to anaerobic organic matter transformations. Anaerobic carbon transformations, involving chiefly rice crop residues, are characterized by the formation of various organic acids. These may accumulate after prolonged incubations in amounts sufficient to be toxic to developing rice seedlings. In these experiments the effects of acetic, propionic, and butyric acids were studied at I, 5, and 10 mN on the growth and nutrition of 14 day old (Oryza sativa L.) cultivar 'Earlirose' rice seedlings. Nutrient solutions were used in the experiments with pH controlled at 6.5 in one experiment and in another the acid concentrations were allowed to attain equilibrium pH with the nutrient solution (I mN ----4.6, 5 mN -= 3.9, and 10 mN = 3.8).Root elongation of rice seedlings was decreased by increased organic acid concentrations at both p]-I's. New root initiation was totally inhibited at all organic acid concentrations at equilibrium pH, and at 10 mN with pFI 6.5. New root initiation at 1 and 5 mN at pH 6.5 allowed increased seedling dry matter production, whereas it was reduced in all other treatments. Plant height and weight were also decreased by increased acid concentrations. At pH 6.5 the plants showed no specific symptoms of organic acid toxicity except reduced growth. At equilibrium pH values specific symptoms were observed.At 1 mN, the seedlings withered, similar to desiccation; at 5 mN the leaf tips showed symptoms similar to bronzing; and at 10 mN the seedlings died after 24 hours.Uptake of both P and K by roots were reduced by increased concentrations of all organic acids at bottl pH's. P concentration and total uptake were re= duced in the shoots with all treatments, whereas the effects on K in shoots were not consistent.The magnitude of organic acid toxicity is a function of the kind, concentration and the degree of dissociation of the acid. Increased media pH reduces the toxicity of the acid concentrations.

Butyric acid tolerance of rice mutant M4 families

“…The highest relative reduction was observed for the variable RL, the most susceptible to butyric-acid toxicity, with up to 31.35% of relative performance at the dose of 6 mM. These results agree with findings of Rao and Mikkelsen (1977b) in rice, who stated that the trait root length is most affected by the organic acid treatments. In a study of the physiologic symptoms related to organic acid toxicity in rice Armstrong and Armstrong (2001) reported that this acid causes cell wall degradation, inhibition of the respiratory functions and consequent reduction of cell division of the root system that is in direct contact with the toxic element.…”

Dissimilaridade genética em mutantes de aveia tolerantes e sensíveis a ácidos orgânicos

“…A acumulação desses ácidos no solo afeta diretamente algumas culturas, principalmente pela inibição da respiração, levando à diminuição no alongamento radicular (CAMARGO et al, 1993b) e na absorção de nutrientes (RAO e MIKKELSEN, 1977a, 1977bCAMARGO et al, 1995b).…”

Phragmites die‐back: toxic effects of propionic, butyric and caproic acids in relation to pH

“…The curve for n-caproic acid (pK a 4n83) lies between those for n-butyric and propionic acids. (Tanaka & Navasero, 1967 ;Rao & Mikkelsen, 1977). At pH 4n5 most of the molecules (63-70%) are in the undissociated form, whereas at pH 6 most molecules ( 92%) are in the non-toxic ionized form (Fig.…”

“…Rao & Mikkelsen, 1977, found that 14 d-old rice seedlings died within 24-48 h when exposed to 10 mM acetic, propionic or butyric acids in the rooting medium at pH 3n8. Even most Phragmites seedlings planted in compostjrhizomes, where the acid concentrations were much lower (total l 3n2 mM; toxic l 0n06 mM), died within 7 d, probably because the total concentration of the cocktail of acids was greater than we detected, since we were only able to analyse four acids.…”

“…Several workers have found that, in rice, higher concentrations of the lower organic acids, including acetic, propionic and butyric, variously reduced the uptake of P, K, Si, Mn, Mg, Ca and NH % -N (Mitsui et al, 1954 ;Takijima et al, 1960 ;Tanaka & Navasero, 1967 ;Rao & Mikkelsen, 1977). It has been suggested that these effects can be correlated with reduced root respiration induced by the organic acids (Tanaka & Navasero, 1967 ;Robinson & Taylor, 1974).…”