Some morphological, physiological and biochemical changes in drought-stressed laurel (Laurus nobilis L.) seedlings

Studies should be conducted on the effects of drought stress on medicinal and ornamental plants and ways to increase their resistance should be sought. This study was carried out in 2021 to determine the effect of drought stress on seedling growth and some physiological and biochemical properties in laurel (Laurus nobilis L.). The seedlings were subjected to drought stress for about 4 months with three different irrigation regimes (Control (every 2-3 days), day 15 and day 30). Morphological (root collar diameter, seedling height, dry weight, stem: root ratio and number of leaves), physiological (midday xylem water potential and photosynthesis properties) and biochemical (photosynthetic pigments, total carbohydrate and proline contents) properties were determined. Drought stress has a negative effect on root collar diameter, seedling height and dry weight. Leaf number and midday xylem water potential decreased due to increased drought stress. The net photosynthesis rate, stomatal conductivity and transpiration rate of the least irrigated (30th day) seedlings are quite low compared to those of control seedlings. Differences in chlorophyll a, chlorophyll b, total chlorophyll and carotenoid contents were found to be statistically significant. Total carbohydrate (in stem and roots) and proline contents showed the highest values for the least irrigated seedlings (30th day) and lowest values for controlled irrigation seedlings. These results reflect the tolerance capacity of laurel to increased drought stress.