Hardwood Cutting Propagation And Effects Of Growth Regulators On Cold Resistance Of Cutting Seedlings Of Zelkova Sinica

Zelkova sinica is a rare native tree species in Shanxi.It has important value of protection,development and utilization.It has important theoretical and practical significance to optimize the hardwood cutting propagation of Zelkova sinica and to study the cold resistance of annual cutting seedlings for expanding the production scale of seedlings,increasing the area of introduction and cultivation and distribution range.The rooting effect of storage methods,substrate types and proportions,concentration of ABT-1 and soaking time on hardwood cutting was analyzed by measuring rooting rate and number of Zelkova sinica cuttings.The effects of exogenous growth regulators on the cold resistance of cuttings were analyzed by measuring the electrical conductivity and MDA et al.The results are as follows:（1）The rooting of hardwood cuttings of Zelkova sinica was significantly affected by different storage methods.The rooting rate of wet sand burial in cellar and natural overwintering cuttings were significantly higher than that in refrigerator.The rooting rate of wet sand burial in cellar of hardwood cuttings was the highest.It was 83.33%.The longest root length and rooting number were better than natural overwintering and refrigerated cuttings.The optimum storage method for hardwood cutting was wet sand burial in cellar.（2）The rooting of hardwood cuttings of Zelkova sinica was significantly affected by different substrate types and proportions.The rooting rate of stratified substrate which the volume ratio of peat to perlite is 1:1 was up to 91.67%.It was significantly higher than mixed substrate which the volume ratio of coarse sand to perlite is 1:1,mixed substrate which the volume ratio of peat to perlite is 1:1,mixed substrate which the volume ratio of coarse sand,peat and perlite is 5:3:2 and stratified substrate which the volume ratio of coarse sand to perlite is 1:1.The rooting indexes were also better than other substrates and the cutting effect was the best.The best substrate to promote the rooting of Zelkova sinica hardwood cuttings was substrate 5.（3）Different concentration of ABT-1 and soaking time had significant effects on rooting rate of cuttings.The rooting rate of 200mg·L^-1ABT-1 soaked for 4 hours was the highest,which was significantly higher than that of other treatments.The rooting rate was 95%.The longest root length and rooting numberwere better than other treatments.The best cutting effect was 200mg·L^-1ABT-1 soaked for 4 hours.（4）Different concentrations of CaCl₂,ABA and PP₃₃₃ had significant effects on the physiological parameters of cold resistance in the leaves of Zelkova sinica.Compared with other treatments,20mmol·L^-1CaCl₂ significantly increased chlorophyll and soluble protein content of beech seedlings,decreased MDA content and cell membrane permeability.（5）Different concentrations of CaCl₂,ABA and PP₃₃₃ had significant effects on the degree of freezing injury of cutting seedlings of Zelkova sinica branches.The least degree of freezing injury of cutting seedlings of Zelkova sinica by spraying CaCl₂.Compared with other treatments,20mmol·L^-1CaCl₂ had the lowest degree of freezing damage and the strongest cold resistance.The freezing degree of branches was significantly correlated with the physiological parameters of cold resistance of cuttings.（6）Combining with investigation on freezing damage grade in field and comprehensive evaluation of four cold resistance indexes,the order of cold resistance was CaCl₂ 20mmol·L^-1>CaCl₂ 25mmol·L^-1>ABA40mg·L^-1>ABA 20mg·L^-1>PP₃₃₃ 0.15%>PP₃₃₃ 0.1%>CK.