The effect of drought stress on morphological and biochemical characteristics of some lily species

Drought stress is one of the most important factors limiting plant growth in the world and is the common stress that threatens most of the world and reduces crops. Drought stress are the most common stress that reduces agricultural yields. In some medicinal plants, the use of environmental stresses causes changes in the growth and development of medicinal plants and on the other hand causes changes in the amount and quality of their, effective materials which protect plants against external disturbances as well as unfavorable environmental conditions so that the plants can survive. Today, the use of plant tissue culture techniques in vitro has provided a controlled environment for physiological studies such as the effects of drought stress to achieve maximum yield with more management of environmental factors. This study was carried out in a completely randomized design in the tissue culture and biotechnology laboratory of university of mohaghegh ardabili for in vitro screening of three species of lily for drought stress. In vitro bulblet scales of L. tsingtauense, L. regale and L. ledebourii in MS medium containing different concentrations of polyethyleneglycol 6000 (0, 5, 10, 20 and 40 g/l) was cultured. After two months, morphological characteristics of regenerated plantlets such as plantlets height, leaf length and number, number of bulblets, number of roots and fresh weight, as well as biochemical parameters such as proline, soluble carbohydrates, phenol, flavonoid, anthocyanin, chlorophyll and carotenoid were measured and evaluated separately in each of the treatments. In the present study, among the three species of lily, only L. regale produced leaves. The results showed that the plantlet height, number and length of leaf, number of bulblet and number of root and fresh weight of plantlet decreased with increasing drought stress. The highest number of bulblet was obtained from L. ledebourii, the highest number of root was obtained from L. regale and the highest fresh weight was obtained from L. tsingtauense samples. The highest amount of phenol and carotenoid was obtained from L. regale and the highest amount of proline was obtained from L. ledebourii, while L. tsingtauense had more flavonoid, anthocyanin and chlorophyll than other species. According to the results, the levels of proline, flavonoids and anthocyanin had a positive correlation with drought stress, but the highest amount of soluble carbohydrates and phenol from the treatment of 10 g/l PEG and the highest amount of carotenoid from the concentration of 5 g/l PEG was obtained. In the present study, drought stress by reducing elongation and cell division and by affecting various physiological, biochemical and hormonal processes reduced the growth indices of lily plantlet species, While the amount of biochemical parameters compared to the control accumulated under drought stress conditions. Increasing proline, soluble carbohydrates and secondary metabolites, in addition to increasing crop yield, is a mechanism of drought tolerance and is an indicator for assessing plant resistance to drought stress.