| Malus sieversii is one of the main rootstocks in northwest China and other apple producing areas because of its excellent characters of cold and drought tolerance.However,due to deforestation,overgrazing,the impact of various pests and diseases and open scenic spots and other factors,resulting in a sharp decline in the distribution area of Malus sieversii,has become one of the world ’s endangered remains.At present,the main breeding mode of Malus sieversii is live propagation,and the seeds must be stratification at low temperature for a long period of time to germinate smoothly,and the uniformity of offspring is poor.In this study,the anatomical characteristics of rooting,nutrients,endogenous hormone changes and exogenous hormone regulation technology during the rooting process of softwood cutting were studied,and the physiological changes of softwood cutting rooting of Malus sieversii and the suitable combination of exogenous hormones were discussed,in order to provide technical support for the large-scale production of fine rootstock clones of Malus sieversii and facilitate the promotion and utilization of Malus sieversii as rootstock.The main research results are as follows :(1)The root primordium of wild apple cuttings in Xinjiang belongs to the type of latent adventitious root primordium,and the latent root primordium is produced in the normal growth and development process,indicating that Malus sieversii belongs to the type of easy root.(2)During the rooting process of Malus sieversii,the soluble sugar content of tender branch cuttings reached the highest 2.03% at 20 d after cutting,and the starch content of cuttings reached the highest 1.77%at 40 d after cutting,while the soluble protein content did not change significantly.In addition,the activities of POD,SOD and PPO increased first and then decreased.Among them,POD(1474 U/g?min)had the strongest activity 20 d after transplanting,SOD(68.24 U/g?min)had the strongest activity 10 d after transplanting,and PPO(120.05 U/g?min)had the strongest activity 20 d after transplanting.(3)During the rooting process of softwood cuttings,the highest IAA and ZT contents were 11.7 and14 mg/kg at 0 d,respectively.The ABA content in the first quarter of IAA decreased rapidly at 10 d after cuttings,and reached the lowest at 10 d after cuttings,which were 6.1 and 2.4 mg/kg,respectively.30 d after transplanting,the ABA content reached the maximum of 69.4 mg/kg,while the ZT content decreased to the minimum of 0.58.ZT/IAA decreased first and then increased,IAA/ABA showed a trend of‘up-down-up’.(4)The types of exogenous hormones,hormone treatment concentration and treatment time all affect the rooting effect of Malus sieversii cuttings.The order of the three factors affecting the rooting rate is :exogenous hormone types>hormone treatment concentratio>treatment time.After treatment with different exogenous hormones,it was found that the optimal treatment combination of Malus sieversii tender branch cutting was IBA+NAA+ABT,the concentration was 1000 mg/L,and the treatment time was 10 s.At this time,the rooting rate was 66.67%,the average lateral root length was 40.84 mm,the longest root length was 69.45 mm,the average root number was 1.96 per/plant,and the rooting effect index was 7.99. |
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