Response Of Quince As A Dwarf Rootstock To Adversity Stress And The Effect Of Precocious Fruiting

Six different pear rootstocks,Wb2013,CA1,CAd,CBA,Cc and Pyrus betulifolia Bunge were selected for this study.One-year-old seedings from five rootstocks were transplanted in pots,conducted by natural drought stress,0.2%,0.4%,0.6% salt stress,respectively.The relative conductivity,reactive oxygen species(ROS),photosynthetic physiology index and malondialdehyde(MDA)were measured at different stages after stress treatment.One-year-old dormant branches of CBA,Wb,Cad,Cc,CA1,Wb2013 and Pyrus betulifolia Bunge were used as materials.Under low temperature stress(treatment temperature:-15℃,-20℃,-25℃,-30℃,-35℃ and-40℃),the damage degrees of the pulp,xylem and phloem of the branches were observed and the relative conductivity of leaves was measured at different temperatures.Annual Red Clapp Favorite pear trees grafted on dwarf rootstocks of quince CA1,CAd,CBA,Cc,Pyrus betulifolia Bunge and the three-year-old Red Clapp Favorite pear trees grafted on dwarf rootstocks of quince CA1,CAd,CBA,Cc,Wb,Pyrus betulifolia Bunge and interstock of Hardy and rootstock of Wb were used in this study.The effects of different rootstocks on the growth and physiological metabolism of the Red Clapp Favorite pear trees were studied.The main results were as follows:1.Under drought stress,the growth and photosynthesis of each rootstock were affected with various degrees.The relative conductivity and malondialdehyde content of the leaves increased in different degrees,the activity of antioxidant enzymes increased in the early stage and decreased in the later stage.According to the physiological indexes of pear rootstock under drought stress,drought tolerance from strong to weak were: Wb2013>Pyrus betulifolia Bunge>CBA>Cc>CAd>CA1.2.The growth rate,photosynthetic rate,the relative conductivity,themalondialdehyde content and the antioxidant enzyme activities of leaves were affected to varying degrees by the salt stress.With the extension of stress time and the increase of salt concentration,the more serious the stress damage to each pear rootstock was,the greater the increase of relative conductivity and malondialdehyde content was,and the inhibition of photosynthesis and antioxidant system was to varying degrees.According to the determination of physiological and biochemical indexes of pear rootstocks under different salt concentration,salt tolerance from strong to weak were: Pyrus betulifolia Bunge>CA1>CBA>CAd>Cc.3.Under the stress of low temperature,the pulp,xylem and phloem of all rootstocks were damaged by freezing.As the temperature decreased,the electrical conductivity increased in different degrees,combining analysis REL and the Logistic equation calculate LT50(lethaltemperature 50),LT50 ranging from-28.23℃ to-43.11℃ in different pear rootstocks,and freezing tolerance pecking order was: Pyrus betulifolia Bunge>CA1>CAd>Wb2013>Wb>CBA>Cc.4.According to the height of tree,the branch numbers,short-shoot proportions,flower bud numbers,physiological and biochemical indexes of each rootstock-scion combination,it can be seen that the grafted stocks of quince weaked the growth potential.5.The quince rootstock can improve the fruit quality of the Red Clapp Favorite pear trees.The per fruit weight,the firmness and the soluble solid of Dwarf Red Clapp Favorite pear trees were significantly higher than those of the standard Red Clapp Favorite pear trees.