Effects of Hydro and Hormonal Seed Priming on Seed Germination of Milk Thistle under Saline Stress Condition

Abstract

Salinity is an abiotic stress which has harmful effects on germination of many plants. Therefore, high germination rate and vigorous early growth under salty soils is preferred. Seed priming is a way to increase salt tolerance of plants. An experiment was conducted to investigate the effect of seed priming on germination of milk thistle under salinity condition. The treatments were 4 levels of seed priming (no priming, distilled water as hydro priming and 0.5 and 1.0 mM salicylic acid) and 5 levels of salinity (0, 40 and 80 mM NaCl and 40 and 80 mM CaCl₂). The experiment arranged as a factorial in a completely randomized design (CRD) with three replications. Results showed that salinity decreased germination percentage and germination rate to about 16 and 32% in 80 mM CaCl₂ level compared to control, respectively. The highest mean germination time (5.7 day) were belonged to 80 mM CaCl₂. Radicle and plumule length significantly decreased by 80 mM NaCl and 40 and 80 mM CaCl₂. The lowest seedling weight and seed stamina observed in 80 mM CaCl₂. 0.5 mM salicylic acid improved all traits except mean germination time as compared to control.  Salicylic acid (0.5 mM) improved radicle length under 0, 40 and 80 mM NaCl salinity levels as well as increased plumule length at the 0 and 40 mM NaCl salinity conditions.