Comparative Study On Salt Tolerance Of Malus Sieversii And Malus Robusta Seedlings Under NaCl Stress

This study was based on three old M. sieversii and M. robusta seedlings as materials, combined the method of sand culture and field planting, determined the physiological indexes in membrane permeability, the content of proline and MDA of M. sieversii and M. robusta, leaf anatomical structure observation, combined with the growth status of two apple rootstocks on the southern border, screened out strong salt tolerance ability apple rootstocks.1. Under sand culture condition, at the same salt stress, the content of proline, the activity of SOD and POD protective in the leaves of M. robusta was higher than M. sieversii. The cell membrane permeability and the content of MDA in the leaves of M. sieversii was higher than M. robusta, through the study of salt tolerance, it was determined that the salt tolerance of M. robusta was higher than M. sieversii, this was consistent with the salt tolerance of the two apple stock seedlings in the field. Under salt stress, the content of soluble sugar and soluble protein in the leaves of M. robusta and M. sieversii may be related to the salt tolerance mechanism of each tree species, which is to be futher studied in the future. It is concluded that salt tolerance of the M. robusta is better than the M. sieversii.2. Leaf anatomical structure test showed that: under salt stress, the anatomical structure of the leaves of M. sieversii and M. robusta was changed, cell structure occurred different degrees injury, also produced some adaptability characteristics, so as to improve the salt adaptability, by changing the cellular structure of the body to adapt to the saline environment, under severe salt stress, the structure of leaf cells of M. robusta was damaged lightly, the cell structure of M. sieversii was damaged seriously.3. In the field experiment, in the south of Xinjiang soil physical and chemical properties were found, high soil pH value and high total salt content were main cause of apple rootstock seedling etiolation. In the southern calcareous soil conditions, M. sieversii growed normally, the growth was medium, there were slight yellowing symptom, when was severe, M. sieversii growed slowly, bud was atrophy, and the top edge was red, the apical bud was dead. But M. robusta seedling growed normally, new leaves remain was green, with the seasons completely did not appear obvious chlorosis symptom, and the growth was large, through the determination of the content of chlorophyll, the chlorophyll content of M. sieversii was lower than M. robusta significantly. The field test showed that: the salt tolerance of M. robusta was higher than M. sieversii.