Effect of salinity stress on germination and initial growth of two sunflower cultivars and red-root amaranth in in vitro and hydroponic condition

The effect of salinity levels on germination and growth of sunflower (Helianthus annuus L.) cvs. Euroflor and Record and redroot pigweed (Amaranthus retroflexus L.) was studied in two separate experiments under laboratory and hydroponic conditions. The experiments were in split plot based on completely randomized design. Main plot and subplots were devoted for plant type and salinity level، respectively. The salinity levels were 0، 50، 100، 150، and 200 mM of sodium chloride in laboratory condition. The seeds were placed in each Petri dish separately and 5 ml of salt solution was added and were incubated at 30 °C. The germination and primary growth parameters were evaluated in one week. Increasing salinity levels، caused reduction of germination percentage and seedling growth parameters of sunflower cultivars and redroot pigweed، significantly. The redroot pigweed was less tolerant to salinity than sunflower cultivars in germination stage. In hydroponic condition، the seeds were sown in sand and after plant transferring to Hoagland solution، salinity treatments including 25، 50، 100، and 150 mM of sodium chloride were added to the culture medium. After 4 weeks، the growth parameters and leaf chlorophyll content were recorded. The growth parameters and leaf chlorophyll content were decreased significantly، increasing of salinity levels. In addition to the sunflower cv. Euroflor was less tolerant to salinity than Record and redroot pigweed. The sunflower cv. Record is recommending being cultivated in saline soils.