Appraisal Of Growth And Propagation Of Improved Clones For Populus

Poplar is a hardy,sun-loving,and fast-growing tree with important economic,ecological and social benefits.It has a wide range of varieties and habitats,and the growth of different species or clones varies greatly in different regions.The selection and introduction of good clones or species with strong adaptability for local production are of great significance for the construction of the regional ecological environment and the development of the forestry industry.In this paper,through growth evaluation of introduced Populus clones in Ningxia,three Populus clones with good adaptive performance were selected and propagation tests such as felled stump sprouting,broken root sprouting,cuttings,and group culture were conducted to explore the suitable propagation methods,and the results are as follows.(1)The 39 Populus clones differed significantly in all growth traits except growth potential,and the analysis of variance revealed that 84-315 was more stable and W1-46 was less stable.Principal component analysis reduced the eight growth indicators to three factors with a cumulative contribution of 78.08%.Finally,based on the results of the overall analysis,10 Populus clones were selected,including(Populus tomentosa×P.bolleana)×P.tomentosa 73,(Populus tomentosa ×P.bolleana)×P.tomentosa 66,(Populus tomentosa×P.bolleana)×P.canescens,84-321,Populus tomentosa var.truncate,430,Populus ’Yinhe 2hao ’,NL-80105,105 and NL-80108,as Populus clones suitable for reforestation in Ningxia.Finally,combined with the actual production situation of the forestry field,(Populus tomentosa ×P.bolleana)×P.tomentosa 73,(Populus tome ntosa ×P.bolleana)×P.canescens and Populus tomentosa var.truncata were screened as good clones for subsequent expansion trials.(2)The number of sprouts,height,basal diameter,then several leaves of the three clones were not significantly different,but the sprouts of(Populus tomentosa ×P.bolleana)×P.tomentosa 73 were more suitable for hardwood cuttings because of their larger basal diameter.There was no significant difference between the number of sprouts of the three clones and the growth characteristics of the sprouts between the treatments,but the sprouts of(Populus tomentosa×P.bolleana)×P.canescens cuttings had the most sprouts and were relatively more suitable for root cutting to produce more rootstock for expansion.(3)Hardwood cuttings were found to be a mixed type of healing roots for both Populus tomentosa var.truncate and(Populus tomentosa×P.bolleana)×P.tomentosa 73,but the number of roots produced by Populus tomentosa var.truncate was more than that of(Populus tomentosa ×P.bolleana)×P.tomentosa 73 with the same treatment.ABT-1 rooting powder treatment had the highest healing tissue formation rates(58.33%)in Populus tomentosa var.truncate plugs at 600 mg/L concentration and the same rate in(Populus tomentosa XP.bolleana)×P.tomentosa 73 plugs.;the rooting rates of Populus cuttings of different species were highly significantly different,in which the rooting rates of Populus alba var.pyramidalis hardwood cuttings were as high as 82.14%,while the rooting rates of Populus tomentosa var.truncate and(Populus tomentosa XP.bolleana)×P.tomentosa 73 were only 7.14%and 12.50%.(4)Tissue culture using Populus stem segments to induce axillary buds showed the following results:the best induction medium for primary culture was MS+0.5 mg/L 6-BA+0.05 mg/L NAA,and then successive proliferation culture was performed to make the buds more robust,and then the best induction medium for rooting culture was screened as MS+0.05 mg/L IBA+0.02 mg/L NAA.The highest browning rate and lower vitrification and contamination rates were observed at different culture stages.The above experiments showed that Populus tomentosa var,truncate was more suitable for expansion by group culture test;(Populus tomentosa ×P.bolleana)×P.tomentosa 73 was more suitable for expansion by stump budding test;(Populus tomentosa ×P.bolleana)×P.canescens was more suitable for expansion by broken root budding test,and the budding tillers obtained by the stump budding test could be used as cuttings for hardwood cuttings.In addition,the asexual plants of Populus tomentosa var.truncate and(Populus tomentosa ×P.bolleana)×P.canescens can be obtained by tissue culture.