Understanding the action mechanism of allelochemicals from sugarcane (Saccharum spp)

SAMPIETRO, D. A.; SGARIGLIA, M. A.; SOBERÓN, J. R.; QUIROGA, E. N.; VATTUONE, M. A.

California - Estados Unidos

Congreso; Botany 2006; 2006

Botanical Society of America - American Bryological and Lichenological Society - American Society of Plant Taxonomists - American Fern Society

IN a previous study, we suggested that organic molecules from sugarcane straw leachates participate in the root growth inhibition of Bidens subalternans L. However, evidence of a direct effect of these molecules on root growth could not be obtained. The aim of this work was: 1) to establish if organic molecules from straw leachates directly inhibit root growth of B. subalternans L. and 2) to determine if straw leachates can induce a stress response on B. subalternans. Assays were conducted in pots, in controlled conditions. Straw leachates were incorporated to unsterile soil with and without addition of activated charcoal. Leachates from straw ashes were also assayed in unsterile soil. Pregerminated seeds of B. subalternans were used. Soil total phenolic compounds were determined in unsterile soil with and without addition of activated charcoal treated with sugarcane straw leachates or leachates of straw ashes. In each treatment, root elongation and proline content in cotyledons was measured on 7-day-old seedlings. When treated with straw leachates, levels of total phenolic compounds were significantly higher in unsterile soil than in unsterile soil plus activated charcoal. A strong correlation was determined between total phenolic compounds and root growth inhibition. Straw leachates induced proline accumulation in cotyledons of B. subalternans. Proline accumulation was higher in cotyledons of seedlings grown in unsterile soil than in cotyledons of those grown in unsterile soil plus charcoal. No significant accumulation of proline was detected in cotyledons of seedlings grown in soil treated with leachates of straw ashes. Our results indicate that allelochemicals of straw leachates have a direct action on root growth of B. subalternans. These substances induced a stress response in the seedlings exposed to straw leachates. Phenolic compounds may participate in the observed growth inhibition. However, the participation of organic molecules from other chemical natures could not be excluded.