Effects Of Four Yeasts On The Growth Of Apple Rootstock G935 Under Copper Stress In Orchard Soil

Copper is one of the essential trace elements in the normal growth and development of plants.However,as a heavy metal,high concentration of copper can produce toxic effects on plants,resulting in decreased yield and quality or even crop failure.In addition,it may affect the health and safety of animals and human beings.In this experiment,the effect of four yeasts of Saccharomyces cerevisiae（JM-1）、Meyerozyma caribbica（JM-2）、Pichia fermentans（JM-3）and Meyerozyma guilliermondii（JM-4）on the growth of apple rootstock G935under copper stress in apple orchard soil were investigated.The main results were as follows:1、The growth of G935 was differently inhibited by Cu treatment alone and the inhibition degree of Cu7 treatment is more obvious than that of Cu4 treatment.Leaf chlorophyll content,photosynthetic performance,plant biomass and normal growth of roots were inhibited.The Cu content in each tissue of the plant increased significantly compared with CK,and the order of Cu content was root>leaf>stem.At 15 d and 30 d,SOD activity in leaves and roots of plants treated with high concentration of copper stress was significantly lower than CK.However,the activities of POD and CAT increased at first and then decreased.The content of MDA in leaves and roots increased greatly,and the content in leaves was far greater than that in roots.2、After the four yeasts were applied to the soil,the chlorophyll content in the leaves of G935 was increased obviously,and the JM-2 treatment was the best.The photosynthetic capacity of JM-2 treatment was significantly higher than that of the same concentration of Cu alone.When the concentration of Cu²⁺was 700 mg·kg^-1,the application of four yeasts could increase the plant biomass significantly.At 30 d,the root activity of JM-2+Cu7 treatment was significantly higher than that of the other three treatments with the same concentration.Under two high concentration Cu treatments,JM-2 and JM-4 treatments can reduce the Cu content significantly in plant tissues.At 15 d and 30 d,the SOD activity of JM-4+Cu4 treatment was significantly higher than other treatments.At 30 d,JM-2+Cu4 treatment can significantly enhance SOD activity in leaves.The activities of POD and CAT decreased when Cu²⁺concentration was 400 mg·kg^-1,and increased when Cu²⁺concentration was 700 mg·kg^-1.Under the treatment of two high concentrations of Cu,JM-2 had the best effect on POD activity in root system among the four yeasts.The change degree of POD activity by each yeast was basically the same in 15 d and 30d.At 15 d,JM-3 could affect the activity of CAT significantly in roots under two high concentrations of Cu.At 30 d,JM-3+Cu7 had the best effect on CAT activity in root system.However,under the treatment condition of 400 mg·kg^-1,the effects of the other three yeasts were better than JM-3.Based on the analysis of the above results,JM-2 and JM-4 treatments have better overall effect on relieving high concentration copper stress.