Conditions needed to study allelopathic effect of plant extracts

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

Tucumán (Argentina)

Congreso; XVIII Annual Meeting of Tucuman Biology Society; 2002

Tucuman Biology Society (publicado en Bio Cell 26 (1), 162, 2002)

Inadequate control of growth factors could lead to wrong results in bioassays of the allelopathic effect of plant extracts. The aim of this work was the evaluation of pH, light and osmotic potential on germination and seedling growth. In each Petri dish 25 seeds of Lactuca sativa var Grand Rapids were placed on Whatman N°1 paper and 3 ml of solution (NaCl, pH or distilled water controls) was added. After 96 hs, shoot lenght, rooth elongation and germination were measured. The highest germination and root elongation was measured at 12hs light/dark. Shoot lenght was maximum in dark. Root elongation increased with higher pH levels. The highest shoot lenght was measured at pH 6,5 and the lowest at pH 5. Germination was similar for all treatment. Petri dishes without parafilm seal were affected considerably by osmotic pressure. The interpretation of shoot response was not clear. Conclusions: Root elongation is the most suitable parameter for quantification of allelopathic effect of plant extracts on lettuce growth. pH and Osmotic pressure should be adjusted at 5-6,5 and 40 mOsm, respectively.