Oxygen electrode for seedling metabolism measurements in allelopathy

Measurements of photosynthetic and respiration rates are essential to quantify the primary effects of an allelochemical on plant metabolism. Oxygen electrode had been used to test the physiological effects on photosynthetic and respiratory metabolism in adult plant parts and cell organelles. So, we have resolved to set up and improve these measurements on seedlings to obtain more accurate data in experiments, where natural chemical compounds are involved and interact with plant metabolism. The oxygen variation in course time was used to measure the photosynthesis and respiration rates of seedlings and plants parts of Lactuca sativa L., incubated in 2-benzoxazolinone (BOA), at 30ºC. This method has two advantages: (i) it needs small quantity of media volume and (ii) a very small quantity of plant material, that allows studies in the first stage of the plant development. Currently, this method can not be used in allelopathy, due to difficulty to standardise the experimental procedure and the use of whole seedling. So, we set it up, to determine the accurate respiration and photosynthetic rates on seedlings of L. sativa and for its simplicity to operate in allelopathic studies.