Effect of pre-treatment with auxin on germination, growth indices and pigments of radish (Raphanus sativus) under salinity stress

To evaluate the effect of pre-treatment with auxin on germination and growth indices and pigments of radish under salinity stress, this experiment was conducted as a factorial in a completely randomized design (CRD) with four replications in Seed Science and Technology laboratory of Shahed University in 2017. Experimental factors were included auxin at four levels (control, 0.2, 0.4 and 0.6 mg/lit) and salinity at four levels (control, 40, 80 and 120 mM CaCl2). In this experiment, germination and growth indices were evaluated and the results showed that interaction effect of auxin and salinity was significant on all evaluated indices except chlorophyll a. The minimum amount of mean germination time (1.59 days) obtained at highest level of salinity and 0.6 mg/lit of auxin that showed 32 percent reduction in compared with the control. Highest germination rate (0.75) obtained at 0.6 mg/lit of auxin and 40 mM salinity that showed 70 percent increase in compared with the control. Radicle in this plant showed more growth in compared to plumule under salinity stress that show the sensitive of plumule has been more than radicle. Maximum mean of carotenoides (19/73 μm.ml1-) were obtained at 0.4 mg/lit of auxin and zero salinity (control) that showed 123 percent increase in compared with the control. Generally, in this experiment, salinity reduced the evaluated indices but using auxin especially 0.6 mg/lit could improve germination indices and 0.4 mg/lit could improve pigments