Phytotoxicity of aqueous extracts from sugarcane leaves

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

Denver, Colorado, USA

Congreso; Annual meeting of the American Society of Plant Biologists; 2002

American Society of Plant Biology

The litter of sugarcane (Saccharum sp) left on the field after harvesting have an important capacity to inhibit weed growth. The purpose of this work was the evaluation in laboratory conditions of the phytotoxicity of aqueous extracts of sugarcane leaves on Lactuca sativa var Grand Rapids germination and radicle elongation. Furthermore, the influence of physical and physico-chemical factors on plant growth were evaluated. Ground-dried leaves from sugarcane var CP (Tuc) 77-42 and CP 65-357 were shaken in distilled water for 48 hours at 30 ºC. After clarification of the extracts, the phenolic content was determined. The bioassays were made in Petri dishes containing Whatman N°1 paper moistened with 3 ml of dilutions of each test solution. Controls of ionic strength, osmotic potential and pH were made. A light-dark period of 12 hs, at 25±2°C was applied. After 5 days seed germination and radicle length were measured. The concentrations of phenolic compounds of 0.1 and 0.25 mM produced a radicle length inhibition of 25% and 39%, respectively, for both varieties (Dunnet T3, p<0.05). This inhibition was more noticeable on radicle growth than on germination. The observed phytotoxic effect of sugarcane extracts could not be explained throught the influence of physical or physico-chemical effects (ionic strength, osmotic potential and pH). Our results suggest that sugarcane leaves under incipient decomposition should contain phytotoxic compounds that may have detrimental influence on plant growth