Studies On Propagation And Adaptability Of Introduced Dwarf Conifers

Dwarf conifers are the selected cultivars with low height, colorful leaf and variegated shape, and are widely applied in European and American gardens. Chinese original ornamental genetic recourses of conifer will be enlarged to improve gardening sight, once they introduced successfully. Five cultivars or species (Juniperus squamata 'Blue Star'; Juniperus communis 'Gold Cone'; Juniperus chinensis 'Plumosa Au rea'; Juniperus×media 'Pfitzeriana Aurea and Picea pungens)were selected from thirteen introduced dwarf conifers according to ornamental value, phenophase and growth data in Beijing, the cutting propagation technologies of them were studied systemically, In addition , the best rooting treatment of Blue Star' and the regeneration system of blue spruce somatic embryos were researched; Meanwhile, cold resistance behavior and mechanism of four conifers in winter, photosynthetic characteristics and shade-tolerance in Summer were analyzed. The results were as follows:(1) Planting technologies of introduced conifers were established, and eight species with higher ornamental and more vigorous growth were selected, including Juniperus squamata 'Blue Star', Juniperus communis 'Gold Cone', Juniperus chinensis 'Plumosa Aurea', Juniperus×media 'Pfitzeriana Aurea', Picea abies 'Nidiformis', Picea pungens' Glauca. Globosa', Picea pungens 'Hoopsii', and Taxus baccta 'Summergold', according to the three — year observation of ornamental value, phenophase and growth data in Beijing.(2) Effective fitting technology of cutting propagation of Juniperus squamata 'Blue Star' was established, and the best grade cutting with a large number per seed-tree and higher rooting ability was selected by the researches on the effect of growth regulators and metabolism regulators on rooting, and the analysis of the hormones, anatomical structure, rooting trait and process of different grade cuttings. The results showed, the optimized means were the softwood cuttings treated by perlite+ABT1000 mg·L^-1(dipped for 2～3 s), with 66.7% rooting rate and wood cuttings treated by perlite + ABT^1#500 mg·L^-1 (soaked for 1h), with 60.17% rooting rate and better rooting qualities. Although there were obvious differences in hormone content among five different grade cuttings, their rooting ability would be promoted with suitable growth regulators, and the rooting ability of cutting grade I was the bestwith an 80% rooting rate and better rooting qualities compared with others, when treated by ABT^1#500 mg·L^-1 (soaked for 1h). Different rooting characterize among them was found, and the adventitious roots of cuttings from grade I to IV mostly originated from cortex of cuttings, but grade V from callus tissue of the cuttings' bottom section. When metabolism regulator with different concentration was added, rooting rate was increased. Grade IV and Grade V were selected suitable cuttings, for 80% rooting rate of the former when treated by ABT1000 mg·L^-1(dipped for 2～3 s) and 1/4MS+NaHSO3 (400mg·L^-1), and the rooting rate of the latter rose 23.3% compared with control experiment, when treated by 1/4MS+NaHSO3 (400mg·L^-1) , which was the result that the metabolizability of cuttings were strengthened, photosynthetic production accelerated and nutrition of cutting base increased. (3) The regeneration system of blue spruce somatic embryos were reasearched. Embryogenic cultures were initiated from mature zygotic embryos on the medium of DCR,1/2LM, the samt as the embryog -ni callus subcultured and multiplicated. 45.3% embryo-genic callus were obtained from DCR medium+ 2, 4-D1.0 mg·L^-1 +6-BA0.5 mg·L^-1 +KT0.5 mg·L^-1 to DCR medium +2, 4-D1.0 mg·L^-1+ 6-BA0.5 mg·L^-1 +KT0.5 mg·L^-1.. The highest requency of proliferation of embryogenic callus on the DCR + 2, 4-D 1.0mg·L^-1 +6-BA0.5 mg·L^-1+ KT0.5 mg·L^-1 was up to 102.27%. The produce of somatic embryos could be increased on the DCR medium supllemented with IBA, and had 38.10% introduction on the medim with IBA0.5 mg·L^-1+ABA2.0 mg·L^-1. Abornomal somatic embryos often appeared during the process of somatice embyos, including germinating prematurilly, making radicel callus, unipola,and so on, which induced the low conversion rate from somatic embryos to normal plants. (4) The adaptability of the introduced conifers in Winter were researched and mode of evaluation of them were established, according to their behave in Winter and researches on the changes in physiology including membrane permeability and content and proportion of fatty acid, protecting enzyme system and lipid peroxidation, and chlorophyll content and chlorophyll fluorescence characteristics. The worst one was 'Gold Cone', for membrane were harmed and had maladjustment of metabolism induced by more simple protecting enzyme system, fewer content of unsaturated fatty acid and having not adjustment reaction duly in Winter. The Indexes of cold damages of 'Blue Star' and 'Pfitzeriana Aurea' were 2.8 and 2.3, of which the cold-resistance were better than that of 'Gold Cone', as the membrane could be protected from superoxide free radicals for the increase of protecting enzyme system content, and the fluidity of membrane be strengthened when the content of unsaturated fatty acid was increasedfast during Winter. The damages of them accounted for the decomposition of chlorophyll and sever photooxidation of conifer. 'Plumosa Aurea', with the 1.7 index of cold damage, was the best cold-resistance one. It was not only for the increase of enzyme system content protecting the membrane from damage, and enhancement of the fluidity of membrane for the more content of unsaturated fatty acid by itself, and increase of them in time during Winter, but also the less photooxidation and fastly resume when early spring. 'Gold Cone' should be planted in the lee and sun-shining condition, to avoid the injure from cold, and to escape the photooxidation of overwintering conifer needles, Juniperus squamata 'Blue Star' Juniperus × media 'Pfitzeriana Aurea' were adapt to be planted under the sparse forest.(5) Photosynthetic characteristic and shade-tolerance speciality of four dwarf conifers were researched, and the ability of shade-endurance followed the order of 'Blue Star'>'Gold Cone'>'Pfitzeriana Aurea'>'Plumosa Aurea', according to the changes of ornamental, growth, configuration and photosynthetic characteristic in different sunlight (full sunlight, 50%,25%). In the garden, Pfitzeriana Aurea' and 'Plumosa Aurea' were suitable to be planted in the open field, 'Gold Cone' could keep the original ornamental and growth under the light from 50% to full sunlight. The best shade-torlerance one was 'Blue Star', and would become the good cover plants for good ornamental under lowest sunlight.