| Abstract |
Ozone concentrations have been constantly increasing since the second half of the 19th century. During the last century, tropospheric ozone levels have more than doubled and they are expected to continue to increase at an even faster rate in the future. Ozone is a powerful transported pollutant and it is therefore considered as a cross-border problem with serious repercussions on living organisms. In the Mediterranean area, the values of this pollutant are particularly high; monthly average values from the station of Finokalia in eastern Mediterranean (Crete) are among the highest in Europe during the whole year probably because of the large amount of sunshine in the region. The negative impacts of the ozone on cultivated areas have been known for the last fifty years. However, during the last decades, ozone has started to become a major cause for concern for cultivated areas, in Europe as well as in the United States. There is substantial evidence that current concentrations of this pollutant are high enough to cause a decrease in the production of cultivated plants and to affect the composition and variety of ecosystems. It has been estimated that a 25% decrease in the environmental ozone would bring an annual profit of at least $1-2 billion in the United States only. This study includes data regarding ozone concentrations in the Mediterranean area and Greece, in particular, during the last years. Physiology data of the plants are presented here in order to offer a better understanding of the entrance and transfer course of the ozone inside plant tissues as well as its phytotoxic results. The study also includes data from previously conducted studies regarding the impact of increased ozone levels in different edible plants in the Mediterranean area. Finally, the study also examines important plants for the nutrition of Mediterranean people as well as people from all over Europe regarding the impact of ozone in their nutritional value. Plants have been divided in two categories according to their edible part. The first group included plants, whose edible parts are their fruit or other storage organs (root tubers). Ozone impact in the nutritional components of these plants is secondary and related with phloem loading mechanisms and photosynthetic product transport. The second group includes plants whose edible parts are their leaves (leaf vegetables) and where ozone impact can be characterized as primary, given the fact that the immediate goals of its phytotoxic action are the leaves. Leaves constitute the entry points of the ozone, through their stomata, into the plantlike tissues. Both groups have exhibited dismal effects in the growth and development of plants due to the high concentrations of ozone in the troposphere. With relation to the quality and nutritional value of products, the effect of ozone in the first group concerns mainly the macro-nutrients (carbohydrates, proteins), while in the second group the effect concerns mostly the micro-nutrients such as vitamins. Changes in different anti-oxidative plant substances have also been reported as well as changes in anti-nutritional factors such as alkaloids in potatoes.
|
Βιβλιογραφική επισκόπηση των επιδράσεων του τροποσφαιρικού όζοντος στις βιοχημικές παραμέτρους των εδώδιμων φυτών
