Response of narrow-leaved ash seedlings (Fraxinus angustifolia vahl.) to water deficit

This study attempts to determine the physiological and morphological reactions exhibited to water deficit by Narrow Leaved Ash (NLA, Fraxinus angustifolia Vahl.) seedlings. The seeds were collected from eight ecologically different populations of the species, and 1+0 pot seedlings were grown for that purpose. During second vegetation period, the seedlings were put under 3 different watering treatments as W1: 280 ml, once in 2-3 days (field capacity amount), W2: 140 ml, once in 3-4 days (50% of field capacity) and W3: 70 ml, once in 3-4 days (25% of field capacity). During June-September period, various physiological and morphological measurements were carried out on the seedlings mid-monthly. The results were analyzed and thus attempts were made to determine the reactions exhibited by the populations to water deficit. The physiological measurement showed an increase in proline and soluble carbohydrate concentrations, and a decrease in plant water potential, chlorophyll a, chlorophyll b, total chlorophyll and carotenoid concentration, in general, from June measurement to September measurement with decreasing watering (from W1 to W3). Photosynthetic efficiency (Fv/Fm) values showed a decrease from W1 to W3 in June measurement; and the measurements in other months showed similar values for W1 and W2 applications and higher than W3. In respect to the results obtained; Ciftekoy-Nigde, Yavuzeli-Gaziantep, Tufanbeyli-Adana and Akinci-Tokat populations were found to be avoidance of drought; Sarikum-Sinop, Bayramdere-Bursa, Yenidogan-Sakarya and Igneada-Kirklareli populations drought tolerant. Furthermore some other analysis results showed that Akinci-Tokat population had drought tolerant capability and Yenidogan-Sakarya population drought avoidance. In terms of morphological properties, all the populations provided adequate root/shoot dry ratios growth with a value over 2.14. Drought avoidant populations were found to have higher root/shoot dry weight ratios than drought tolerant ones. Shoot dry weight of drought tolerant populations, even during W3 watering, was detected to be higher than W1 watering treatment of drought avoidant populations. Water deficit with a longer period of time generally appears in the habitat conditions of populations showed drought avoidance behavior. Considering the study results, it might be advised that especially drought avoidant NLA populations are utilized in erosion control applications in semi-arid areas, and drought tolerant ones in afforestation and industrial plantations.