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Evaluación de los efectos del ozono troposférico en las características morfológicas de la especie lactuca sativa

Abstract:

Air pollution is a phenomenon that has increased over the years, mainly by the increase in emissions of greenhouse effect pollutants. These contaminants interact with each other and with the environment producing secondary pollutants. Ozone O3, when located in the stratosphere forms a layer that protects the planet from ultra violet radiation, but when in the troposphere can be harmful to life. Studies have shown that the concentrations of ozone are not constant throughout the day and reach their maximum concentrations at noon. The ozone concentrations also present a variation between months. In Ecuador, ozone concentration at midday in September and October vary between 60 and 85 microgram m3, whereas in April and May are set to 40 microgram m3, showing a significant variation between summer and winter months. Ozone have been studied mainly because of the repercussions that can have for human health, but in recent years due to its increase in tropospheric concentrations, studies have been indicating its effect on vegetation as well. Some of the studies have shown that ozone generates imperfections on a wide range of crops. Lettuce with scientific name Lactuca sativa is one of the crops that has a great demand in the market and in the last years, more cases have appeared of these crops used in urban agriculture. This study aims to evaluate the effects of tropospheric ozone on the plant species by designing and building an experimental system for the variety Lactuca sativa L. known by its common name romaine lettuce. The study was performed from March 4th to May 20th 2017 in central Quito, Ecuador .The plants were exposed to two different treatments with different ozone concentrations of 40 and 80 microgram /m3 respectively, performing observations and identifying the changes occurred on the plants development. The results confirm that lettuce leaves are sensible to ozone concentrations, and this sensitivity were show in the appearance of spots on the leaves closer to the ground. This work suggests that the increase in urban ozone concentrations could result in significant economic losses due to the esthetic damage to the leaves the economic value of this species.