Activities of photosystem II and antioxidant enzymes in chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L<Emphasis Type="Italic">.</Emphasis>) cultivars exposed to chilling temperatures

This study was carried out to determine the effect of chilling on both cold-acclimated and non-acclimated chickpea (Cicer arietinum L.) cultivars (Gökçe and Can?tez 87). Chickpea seedlings grown in soil culture for 12 days were subjected to chilling temperatures (2 and 4°C for 12 days) after maintaining in cold-acclimation (10°C, 7 days) or non-acclimation (25°C, 7 days) periods. The lowest values of growth parameters were obtained with cold-acclimated plants, whereas non-acclimated plants exhibited the lowest water content values, especially at 2°C. There was no effect of cold-acclimation period on chlorophyll fluorescence parameters. Plants subjected to chilling temperatures after cold-acclimation were more tolerant with respect to chlorophyll fluorescence parameters, and Gökçe had better photosystem II (PSII) photochemical activity. In the chilling treatments, total chlorophyll (a + b) content reduced, especially at 2°C, while anthocyanin and flavonoid contents increased to a greater extent in Gökçe and carotenoid content of the cultivars did not change. Malondialdehyde (MDA) content was higher for Can?tez 87, mostly at 2°C, while proline accumulation was greater for Gökçe. The cold-acclimation period led to a remarkable increase in antioxidant enzyme activities of both cultivars. The superoxide dismutase (SOD) activity was much higher in Gökçe for both chilling temperatures and the ascorbate peroxidase (APX) activity increased only in the cold-acclimated 4°C treatments. Similarly, with APX activity, the glutathione reductase (GR) and peroxidase (POD) activities of cultivars were higher in cold-acclimated plants at both the chilling temperatures, mostly in Gökçe. The results of this study indicate that cold-acclimation increased the cultivars ability to withstand the chilling temperatures. The lower MDA content and higher antioxidant and photochemical activities in Gökçe indicated an enhanced chilling tolerance capacity of this cultivar to protect the plant from oxidative damage.