Abstract
Proline is one of the substances which can be used as a parameter of the reaction of a plant to an environmental stress. In this study the changes of proline contents in some ecophysiologically different plants, such as Helianthus annuus and Atriplex hortensis (plants in cool climate regions) and Cicer arietinum, Amaranthus retroflexus and Panicum milliaceum (plants in warm climate regions), were observed when the roots were subjected to high and low temperature stress. When these plants were grown for 2 weeks at 10, 18 and 28°C root temperature, at higher root temperature proline contents of both the roots and the shoots tended to increase in cool climate plants and vice versa, to decrease in the case of warm climate species. On the other hand, when the plant roots were subjected to temperature stress shifting from high to low or low to high and after the shifting they were kept at these temperatures for a short period such as 90 min, the contents of proline increased in both the shoots and the roots irrespective of the temperature shift and the ecophysiological difference of plants. In general, therefore, it seems that the plants tend to accumulate proline when they are subjected to temperature stress at short time. However, the increased proline content in the case of low temperature stress was higher in the warm climate plants than in the cool climate plants.
