INFLUENCE OF SALT STRESS ON SOME PHYSIOLOGICAL CHARACTERISTICS OF TWO LYCIUM VARIETIES GROWNEX VITRO IN HYDROPONICS
VELMIRA DIMITROVA2*, TEODORA GEORGIEVA2, YULIANA MARKOVSKA1
1 – Department of Plant Physiology, Faculty of Biology, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
2 – Biotree LTD, Sofia, Bulgaria
* Corresponding author: velmiradimitrova@gmail.com
Keywords: Lycium barbarum, Lycium chinense, fresh/dry ratio, plastid pigments, proline, salinity
Abstract: Lycium chinense is one of the two species of boxthorn in the family Solanaceae from which the goji berry is harvested, the other being Lycium barbarum. They differ morphologically. The plants are used in traditional Chinese medicine for the treatment of pneumonia, cough, inflammation, and diabetes mellitus.
We studied the effect of salt stress on growth parameters, pigment and proline contents in Lycium varieties grown ex vitro as hydroponic cultures at three levels of salinity, 50 mM, 100 mM and 200 mM NaCl solution and look for suitable markers for salt tolerance. Content of proline, which is selected as stress marker, increased more in the leaves of Lycium barbarum. The ratios of fresh weight/ dry weight were enhanced with increasing salinity level for the roots and shoots of Lycium chinense, while this parameter decreased gradually for Lycium barbarum. The ratio of chlorophyll a/ chlorophyll b changed in the same manner in the leaves of Lycium chinense and Lycium barbarum. The ratios of chlorophyll a+b/ carotenoids are reduced in the leaves of both species because the carotenoid content increased during NaCl treatment. Our results suggest that selected markers, such as ratios fresh weight/ dry weight of roots and shoots, chlorophyll a/ chlorophyll b, chlorophyll a+b/ carotenoids and leaf proline content are sensible, but insufficient for characterization of salt tolerance of Lycium barbarum and Lycium chinense, which are micropropaged by BioTree Ltd, Bulgaria.