Effects of Salinity Stress on seed germination and seedling vigor indicesof two Halophytic PlantSpecies (Agropyronelongatum and A. pectiniforme)

ABSTRACT: Screening for seeds with a greater tolerance to salt stress aids in the development of salt tolerant cultivars. Seed germination is a critical point in seedling establishment and subsequent plant health and vigor. The objective of this study was to compare the salinity tolerance of ten ecotypes of two halophytic species(Agropyronelongatum and A. pectiniforme).Salinity treatments consisted of 4 treatments of 0 (control), 50, 100 and 200mM NaCl.20 seeds of each ecotype weregrown in Petri dishes on filter papers. A factorial experiment based oncompletely randomized design with 3 replicationswas conducted. The results showed that by increasing of the salinity level, germinated seeds number, root, shoot and seedling length, shoot and seedling fresh weight, mean daily germination (MDG) and seedling length vigor index (SLVI) decreased, while daily germination speed (DGS) increased in all studied ecotypes. Additionally the ecotypes of A.elongatum were more resistant to salinity stress in comparison to the species of another species.The minimum germination ratebetween these ecotypes was related to 3202, while between the salinity treatments the maximum germination rate was observed in 6990 ecotype. Only in control treatment, the maximum germination rate was related to 7819 ecotype by 100%. There was a negative correlation between two indices of mean time to germination (MTG) andDGS and other indices.