Environmental stress especially drought is one of the most important factors to reduce and disturbance in different stages of floral growth especially sprouting in dry and semi-dry lands of Iran. For this purpose a factorial essay executed in accidentally manner with four iterations in vitro condition. Four genotypes of Bromus tomentellus pasture types were used (92 Tehran, 630 Kordestan, 3414 Shahrekord and 9507 Lorestan) and four drought care (-3, -6 and -9 times distilled water). In this essay the sprouting percentage, Root length, Shoot length, Seedling length, Root length to Shoot length rate, Seedling dry weight, Seedling fresh weight, dry to fresh weight rate sprouting rate and seed health index were determined. The result showed that the with stress drought increase, all attributes except the dry weight to fresh weight proportion reduced significantly. The reduction in all under assessment properties were from -3 to -6 in potential. In general, in tested genotypes, Lorestan (9507) genotype showed a better sprouting in under study potentials and had a meaningful preference to other genotypes. From assessed parameters, Seedling length and seed index standard showed the most possible reaction to changing potential of water. The best levels to assess the stability to drought were the -6 and -9 load potentials in all drought levels.