Effect of a sugarcane straw leachate and its chemical constituents on plant growth in soil conditions

SAMPIETRO, D.A.; ISLA, M.I.; VATTUONE, M.A.

Allelopathy: Establishing the scientific base

Regional Institute limited

Lugar: Wagga Wagga (Australia); Año: 2005; p. 352 - 354

In a previous study, we isolated three phenolic acids from sugarcane (Saccharum officinarum) (Poaceae) straw leachate. The aim of this work was to evaluate the leachate and its isolated constituents on plant growth in unsterilised soil, autoclaved soil and autoclaved sand. Amaranthus quitensis L., Bidens subalternans L. (Asteraceae), Brassica campestris L. (Brassicaceae), Sida rhombifolia L. (Malvaceae), Lactuca sativa L. (Asteraceae), Raphanus sativus L. (Brassicaceae), Sorghum bicolor (L.) Moench (Poaceae) and Triticum aestivum L. (Poaceae) were selected as test plants. In unsterile soil, straw leachates stimulated the growth of some test plants at the lowest assayed concentration and inhibited root elongation of all of them at higher concentrations. The leachates inhibited root elongation in unsterile soil more than in autoclaved soil. In autoclaved sand, the inhibitory effect was stronger than in autoclaved soil. In unsterile soil, phenolic acids stimulated radicle growth of some test plants at low concentrations but were inhibitory at higher concentrations. Vanillic acid was more inhibitory than ferulic and syringic acids. Phenolic acids inhibited root growth of test plants in autoclaved soil more than in unsterilised soil. Otherwise, the test plants were more inhibited in sterile sand than in autoclaved soil. Our results suggest that soil microflora and adsorption influenced the biological activity of the straw leachate and its phenolic acids. The leachate content of vanillic and ferulic acids is high enough to inhibit seedling growth of some test plants. However, the phytotoxic effect of these compounds was weak and can not completely explain the strong inhibitory activity of sugarcane straw leachate.