Evaluation of growth and physiological responses of fifteen petunia cultivars to salinity stress for introducing tolerant and sensitive cultivars

Soil and water salinization has become the most important factors limiting the development and maintenance of urban landscape in Iran. Petunia (Petunia hybrida) is an important seasonal flower which understanding of tolerance level and the responses of its cultivars to salt stress is critical for preservation and development of this species in landscapes. The present study was aimed at evaluation of salt tolerance of fifteen petunia cultivars by investigating the effects of salt stress on the plants‟ growth and physiological responses. The petunia cultivars consisted of five Persian, five Dutch and five English cultivars which were subjected to three concentrations of NaCl in the Hoagland‟s nutrient solution (0, 25 and 50 mM NaCl) from seed sowing to flowering stage. The treatments were arranged as a factorial experiment based on a completely randomized design with three replications. 60 days after sowing the seeds, survival percent, biomass, leaf number, leaf area, root length, stem length, root volume of the plants and traits related to relative chlorophyll content and efficiency of chloroplast photosystem centers in the plant leaves were evaluated. Salt stress significantly reduced the plants‟ growth and by reducing leaf chlorophyll content and affecting the chloroplast photosystem centers, reduced the plants‟ efficiency in light harvesting. Under salt stress, „White Calibrachoa‟ (Persian) and „Prism White‟ (English) had the highest survival, growth, chlorophyll content and chloroplast health level than the other cultivars, and therefore introduced as the most salt tolerant cultivars. These cultivars were suggested for developing urban landscapes in salt prone areas and for using in controlled hybridizations to obtain new salt-tolerant petunia cultivars

Keywords:

Biomass , Growth , Photosystem efficiency , Chlorophyll content , Petunia hybrida