Assessment of exogenous application of plant growth regulators on Cress seed germination and ?-Galactosidase activity

Plant growth regulators (PGRs) were involved in several types of abiotic stress responses by means of improving seed germination and modifying the growth and development of medicinally important Lepidium sativum via alleviating the negative effects of abiotic stresses. Therefore, the present research was carried out to investigate the effects of exogenous application of PGRson seed germination, protein content and ?-galactosidase activity of L. sativum. Germination of L. sativum seeds was monitored for a short interval after the start of incubation until growth became 100%. While cytokinin treatment showed a positive effect on seed germination more than Gibberellic acid (GA), salicylic acid (SA) produced a higher negative effect than auxins. Quantifying changes in total protein content during seed germination as influenced by PGRs revealed that all PGRs have to exert a positive effect arranged in the following order: SA ? auxin ? cytokinin ? GA. Parallel to changes in germination percentage and total protein content of seed, a negative effect was attainedon ?-galactosidase specific activity in response to PGRs with the following arrangement: SA ? auxin ? cytokinin ? GA.In conclusion, the present study proposed the potential importance of the type and magnitude of exogenously applied PGRs during the germination of easily or even more difficult-to-germinate seeds.