Estimation the potential effects of osmotic (salinity and drought stress) on germination of clodinafop-propargyl resistant and susceptible biotypes of rigid ryegrass

Laboratory studies were conducted to compare the relative fitness of clodinafop-propargyl herbicide resistant Lolium rigidum accessions with their clodinafop-propargyl -susceptible counterparts in 2014. Factors were Lolium populations at constant salinity stress (0, 5, 10, 15, 20 and 25 dS cm2) and drought stress (0, -3, -6, -9, -12 and -15 bar). The maximum germination in salinity stress was among three biotypes regarding susceptible biotype with 93.6 percent. When concentration of salinity to reach 50 percentage, seed germination S and Semi-R biotypes were more than R biotype. In salinity stress the highest rate of germination in the S biotype of 8.66 (number of germinated seeds in days) at a concentration of 17 dS RG reaches 50% in S and Semi-R biotypes and in R biotypes in salinity 14 dS cm2. The results of the application of various potential water showed that the more negative water potential, germination all biotypes (R, Semi-R and S) dropped and in potential -15 bar PG in R and Semi-R biotypes to less than 15 percent. Coefficients from the regression equation sigmoid three parameter to data PG resistant and susceptible biotypes showed that Semi-R biotype Compared to R and S were more tolerant of drought stress and in water potential 7.5, it PG Reduced to 50 percent. In examining the relative fitness of ryegrass biotypes drought and salinity stress showed that Semi-R and R biotypes the cost of considerable fitness, But the most results cost fitness no significant.