Effects of salicylic acid on seed germination and growth parameters of pepper (Capsicum annuum L.) in reduction radiation of different bands of ultraviolet

Salicylic acid (SA) or orthohydroxybenzoic acid and related compounds which are be-long to this group are plant phenolics that play a major role in regulation of many phys-iological processes e. g. growth, development, ion absorption and seed germination. The effect of SA on germination, shoot and root fresh and dry weights, shoot and root length, leaf area, sugar and protein content were investigated of pepper (Capsicum an-nuum L.) under UV-A, UV-B and UV-C radiation. The plants were grown in vermicu-lite. Before applying the treatments, plants were subjected to a based nutrient solution (Long Ashton) for 5 weeks. After 5 week, leaves of plants were sprayed with 1. 5 mM salicylic acid and plants were treated under treatment UV-A، UV-B and UV-C for 2 week. Results showed that the percentage of seed germination significantly increased under UV-A and UV-C with salicylic acid. Rate of germination significantly decreased under UV-C and salicylic acid. In addition decreased leaf area in the UV-applied group were restored by SA application. Shoot and root fresh and dry weights significantly in-creased under UV-A, UV-B and UV-C with SA in comparison with only UV-A, UV-B and UV-C. UV-A, UV-B and UV-C stress and salicylic acid treatment increased stem length but only UV-B and UV-C stress and salicylic acid treatment increased root length. Therefore we concluded that the application of salicylic acid can protect plants against UV-radiation and in terms of improving the measured plant growth criteria. Sugar content significantly increased under UV-A, UV-B and UV-C when salicylic acid were applied. Protein content significantly increased under UV-A when salicylic acid were applied.