Photosynthetic activity as an indicator of drought stress in vegetables
This study evaluated the correlation between actual photosynthetic activity 'A' and irrigation level in selected vegetable species: leek (Allium porrum L. 'Gigante Suizo'), pepper (Capsicum annuum L. 'Slávy F1'), and tomato (Lycopersicon lycopersicum (L.) Karsten 'Proton'), lettuce (Lactuca sativa L. var. capitata L. 'Major') and onion (Allium cepa L. 'Alice'). Onion was irrigated when the available water content (AWC) decreased below 50%. Photosynthetic activity of plants was determined before and after irrigation. Other model plants were grown at two different irrigation levels: 1) optimal; minimum of 65% AWC and 2) reduced (stressed); minimum of 45% AWC. Photosynthetic activity of plants grown under optimum and reduced irrigation levels, were evaluated within the same phenological stage. Plants evaluated in the stressed treatment were exposed to one week of drought period. The intensity of photosynthesis 'A' was determined using a portable gas exchange analyzer (LCpro+). In the case of onion, lettuce, tomato and leek, the intensity of photosynthesis 'A' was substantially lower, irrespective of the developmental stage and the level of soil AWC at the time of measurement. Decrease of the AWC level under 29% led to decrease of intensity of photosynthesis 'A' in pepper crop. The highest variability in the intensity of photosynthesis (affected by drought) was observed in the leek and the lowest observed in lettuce plants under water stress conditions.
Jezdinský, A. and Pokluda, R. (2016). Photosynthetic activity as an indicator of drought stress in vegetables. Acta Hortic. 1112, 39-44
available water content, leek, lettuce, onion, pepper, tomato