Evaluation of Salinity and Deficit Irrigation Tolerance of Two Zinnia Cultivars

Growth and production of ornamental plants are greatly affected by water shortage. Thus, yield enhancement under drought conditions is a major goal of plant breeding. Two commercial Zinnia cultivars (Pro-Fusion and Short Stuff), the drought-tolerance and salinity breeding combinations were selected in this study to evaluate drought tolerance,salinity and to develop initial material for a drought tolerance andsalinity breeding program.Four week-old seedlings were transplanted into soil under greenhouse conditions. Five irrigation treatments (T₁=40, T₂=60, T₃=80, T₄(control) =100 and T₅=120% of the estimated evapotranspiration, ET_c) under five salinity levels (control (tap water), EC₁1.56,EC₂ 3.13,EC₃ 6.26 and EC₄ 9.39 dS. m^-1NaCl and CaCl)  were imposed during a 120-day growing period through a drip irrigation system. Vegetative growth, flowering and yield traits were measured while water use efficiency (WUE) was determined. All vegetative and flowering traits decreased significantly as deficit irrigation levels increased. For T₁ under EC₃ 6.26 and EC₄ 9.39 dS m^-1 flower yield was not production in two cultivars. Significant differences among two cultivars were found for all traits, suggesting that they could be taken into account when selecting for drought tolerance and salinity. Pro-Fusion had good performance under different deficit irrigation treatments and salinity levels, except for T₁ under EC₃ and EC₄ by flower yield.