摘要：Citrus species are sensitive to salinity and such conditions greatly reduce their growth and yield. This study was conducted to evaluate the biomass and proline level changes in six citrus rootstocks, namely alemow, citromelo, rough lemon, volkamerlemon, sour orange and Mexican lime under salt stress. The study was performed in a greenhouse with NaCl and CaCl2 induced salinity treatments as 0.57 (control) and 2.5 and 5 (dS m-1) for twelve weeks. Biomass accumulation and proline content of leaves and roots measured at the end of the experiment. Biomass accumulation decreased with increasing salinity level and the lowest rate of reduction in biomass accumulation observed in sour orange. Increasing the salt levels led to significant increase in proline content of leaves and roots regardless to the salt types. The salt type did not significantly affect the proline level and or biomass accumulation. Proline level was higher in the leaves of all rootstocks compared to their roots. The highest and the lowest proline levels in the leaves were observed in the citromelo and rough lemon, respectively; and the highest and the lowest levels of root proline were found in alemow and citromelo, respectively. Since, the species displayed similar trends in proline increments in responding to the salinity levels and there found no illustrative correlation between sensitivity to salinity and proline accumulation in leaves or roots. It is concluded that proline accumulation is a better index of salinity levels exerted on the plant than the salinity tolerance index.
