The effect of different chitosan levels on some physiological traits of citrange and sour orange rootstocks under salinity stress

Due to the increase in saline lands and lack of suitable lands for growing agricultural products in last decades, the identification of salinity resistant rootstocks is very important. For this purpose, a factorial random experiment was conducted on citrange and sour orange rootstocks with two chitosan levels (50 and 100 ppm) applied in two methods of soil application and foliar spray, under five salinity levels (0, 50, 100, 150 and 200 mM) in greenhouse research of Ferdowsi University of Mashhad. The combination effect of salinity× chitosan× citrus rootstocks was significant on all evaluated parameters. With increase in salinity level the activity of catalase and super oxide dismutase, and the content of proline and total soluble carbohydrate were increased. Also with increase in of salinity stress, some parameters such as relative water content, chlorophyll a, chlorophyll b and total protein contents showed a significant decrease.  Generally, foliar application of 100 ppm chitosan caused the highest salinity tolerate in both citrange and sour orange rootstocks. Sour orange rootstock showed the highest resistance against high salinity stress. According to the results, it can be concluded that sour orange rootstock is more susceptible to salinity stress, and chitosan can improve citrus rootstocks resistance against salinity stress.