Study On Salt Tolerance Of Five Shrubs Of Choenomeles

Through potted culture, growth and physiological characters of five Chaenomeles cultivars, Chaenomeles speciosa, C. japonica'RiYuexing', C. sinensis, C. japonica'DaHeitian'and C. japonica'HongMudan', exposed to NaCl stress (0,30,60,90 and 120 mmol/L NaCl) for 35d were investigated. The salt tolerance of the five Chaenomeles shrubs was estimated by membership function. The main results were described as follows:The salt injury index and salt injury rate of the 5 chaenomeles shrubs increased with the salt exposure time prolonged and NaCl concentration increasing. Difference of salt damage between the five shrubs narrowed down with salinity rising. According to salt injury symptoms appearance time, salt injury rate and salt injurey index, the salt tolerance of the five shrubs were evaluated and listed in the ascending order, C. japonica 'RiYuexing', C.speciosa, C. japonica'DaHeitian', C. japonica 'HongMudan'and C. sinensis.Chlorophyll contents of the five shrubs decreased with stress time extension and salinity increase. But chlorophyll a/b of the chaenomeles plants basically showed a rising trend. While C. Sinensis had gentle changes in both chlorophyll contents and chlorophyll a/b.With stress time extension and salt concentration increase, the relative conductivity of the five shubs increased. And MDA content, H2O2 content and O2-·production rate showed the similar trends under salt stress.With NaCl concentration elevating, proline content of the five trees increased, but to different degree. The higher free proline accumulator was the more sensitive to salt stress. The soluble sugar content of C. sinensis increased with salt stress prolonged. But soluble sugar of the other four shrubs increased at the beginning then dropped at the late stage of salt stress. The soluble protein contents showed significant reduction with increase in NaCl concentration except C. sinensis whose soluble protein contents remain basically unchanged.The five chaenomeles shrubs had a similar trend in SOD, POD and CAT activities under salt stress, which increased at the beginning of salt stress then decreased with the salt stress expanding. But the increase extents and and the appearance time of maximum value of the enzyme activities were different among the five trees. However, the APX activities of C. japonica'DaHeitian'and C. japonica'HongMudan'kept increasing during the salt stress period. APX activity of the other three trees showed the same way as SOD activity. Analyzed by membership function, the salt tolerant ability of the five shrubs was listed in the descending order, C. sinensis, C.japonica 'HongMudan', C. japonica 'DaHeitia',C. speciosa, C.japonica 'RiYuexing'.