فهرست مطالب عباس علیزاده احمدآبادی

In order to study the effects of Humic acid levels and irrigation regimes on the some morphological and biochemical characteristics of Echinacea purpurea L., a pot experiment was conducted as factorial based on randomized complete block design with three replications and four experimental units at research farm of Gorgan University of Agricultural Sciences and Natural Resources, during growing season of 2014- 15. The treatments were four levels of irrigation regimes (40, 60, 80 and 100 percent field capacity) and Humic acid including four levels: (0, 250, 500 and 1000 mg/kg). The results showed that irrigation regimes had significant effect on all measured properties except root length. Humic acid increased all of the growth caractristics and morphological traits in 5% level statistically, while had significant effect on total flavonoid and increased it. Interaction effect of humic acid and irrigation regimes was significant for wet and dry weight of root and shoot, total phenol and flavonoid. So, the Limited irrigation had negative effect on growth and plants increased its phenol and antioxidant component for tolerating of stress. Humic acid increased growth and yield in plants that were faced with stress.

In order to investigate effect of humic acid pre-treatment on germination of Purple coneflower (Echinacea purpurea) plant under drought and salinity conditions, two experiments were conducted in labratory of Horticultural sciences at Gorgan University of Agricultural Sciences and Natural Resources (GUASNR) in 2015, in completely randomized design with four levels of humic acid (0, 250, 500 and 1000 mg.l1-) and five levels (0, -1, -2, -3 and -5 bar) drought and salinity stress in three replications. NaCl and PEG were used for salinity and drought stresses, respectively. Results showed that germination and speed percentages, root and shoot length, root wet weight and seed vigor were, significantly decreased by increasing drought and salinity stresses and were zero in drought and salinity level of -4 bar. Impact of humic acid was significant on the mentioned traits until level -3 bar too. The effect of reciprocal humic acid and drought stress were significant in drought stress just in germination percentage and root wet weight, but in salinity stress were significant in total traits. It can be concluded that germination of purple cornflower seeds has more resistant in drought stress conditions than salinity stress conditions. Pretreatment seed of Purple coneflower with humic acid in saline and dry zones can increase germination resistance.