Studies On Salt-tolerant Indexes Of Apple Rootstocks And Early-phase Evaluation With Hydroponics Systems

The apple rootstock is a decisive factor of apple adaptation to salinity and it can improve apple salt-tolerant ability to screen and breed salt-tolerant on rootstocks. Evaluation on salt-tolerant ability of different rootstocks is one of the most important procedure. Early-phase evaluation by hydroponics methods have shown some advantages ,such as quickness and accuracy, with a broad prospects of application in the future.1. Hydroponics experiments were conducted to study the changes of biological .physiological and biochemical aspects under different levels of NaCl stress with three types of apple rootstocks. Results showed that injury degree, percentage and index of salt damage combined with SODase activity in leaves and the value of RSVa, K ,can be used as evaluation indicators of salt-tolerance of apple rootstocks. The changing ranges is as follows the highest injury degree<3;uninjury percentage>50%;index of salt damage<0.3 ; SODase activity is 1.10 times higher than that of control and RSSa, K is 1.35 times higher than that of control under 0.3% NaCl stress; SODase activity is 1.04 times higher than that of control and RSSa K is 1.14 times higher than that of control under 0.4% NaCl stress. Indexes which we can referent to are the relative leaf expansion rate ,the amount of MDA,TTC reducing activity in root ,plasma membrane permeability and the content of chlorophyll b .The content of proline, K+ and the ratio of [Na*]/[K+] in root cannot be used as indexesl to evaluate salt tolerance in apple rootstocks.2. Hydroponics experiments were undertaken to study the changes of biological ,physiological and biochemical aspects under different compound salt stress with two types of apple rootstocks. Results present the41salt tolerant indicators which have been testified under NaCl as well as the compound-salt treatment .3. In the present experiment a simple hydroponics "incubation house" was made and early-phase hydroponics evaluation system for salt tolerance of apple rootstocks was established. The system includes to prepare subculture plants, induce rooting, transplant and acclimate. The most important procedures and key skills include selecting subculture plants and rooting medium,adjusting pH in solution with KOH and H2SO4 .adding gradually the amount of nutrient solution, raising the concentration of salt solution and providing oxygen property.