| Hibiscus syriacus is an excellent ornamental shrubs with characteristics of long florescence, beautiful flowers, various cultivars and so on, it flowers from early summer to middle autumn when less plants flower in Beijing. So it's significant for landscaping of Beijing. However, the plant had not get enough attention of people in china. 15cultivars were introduced from Shanghai in 2007, and their propagation characteristics, environment adaptabilities must be studied for the reasonable using in Beijing.For the problems mentioned above, the cutting propagation of 15 Hibiscus syriacus cultivars was studied from 2007 to 2008; Electrical conductivity method and growth recovery method were used to determine cold hardiness of 15 different Hibiscus cultivars under the low temperature stress; and comprehensive appraisal was developed with the using of the Analytic Hierarchy Process based on the research above. Conclusions of each research were listed as follow:1. In research of green stem cutting, significant differences were showed between cultivars. The rooting rare of H14 can reach 100% while H12 was just 82%; the middle and up parts of branches were considered best cuttings; the best rooting rate were showed when green stems were treated in GGR of 400ppm, and rooting rates of H1,H3 all reach 100%, 14.44% and 16.67% higher separately than that of CK; vermiculite-perlite(1:3) and perlite-peat-vermiculite(1:1:1) were the best cutting medias in the research, rooting rates of H3,H11 were improved by 10% above than CK; 2 leaves were left each cutting was the best treatment, rooting rates of H1,H4,H6 were 10%, 17.77%,10%higher separately than that of 1leaf left, and there were less difficult and diseases than that of 3 leaves left.2. I In research of hard stem cutting, Significant differences were showed between cultivars; the middle and the lower parts of branches were considered best cuttings; the best rooting rate were showed when hard stems were treated in GGR of 700ppm, and rooting rates of H1,H3 were 100% and 95.56%separately, 14.44%and22.23% higher separately than that of CK; Perlite-peat(1:3)was the best hard stem cutting medias in the research, rooting rates of H3,H11 were improved by 16.66%,10% separately than that of CK; the best rooting effect was showed when the base of hard stem cuttings were made into a shape of a hoof; storing in sand could promote rooting greatly, cuttings that treated in sand rooted 10 days above ahead, and the rooting rates of H1,H9,H14were improved by 10%,18.89% and 4.44% than that of CK. 3. Generally speaking, green stem cutting rooted faster than hard stem cutting, rooting rate was higher, and rooting number was more, however, green stem cutting was more difficult to operate than hard stem cutting. So it's better cut in summer for cultivars that difficult to root, and cultivars that rooting easily could be cutted with hard stems in spring.4. Electrical conductivity method and growth recovery method were used to determine cold hardiness of 15 different Hibiscus cultivars under low temperature stress, it was proved that the cultivars H6,H9,H11,H14have the strongest cold hardiness and can survive at -25℃, so should be broadly used in north china that is cold in winter.5. According to the structure of quality of Hibiscus syriacus and the use in the garden, qualities estimating standard and quality evaluation model were established on the basis of the Analytic Hierarchy Process. 15 cultivars were judged by the quality evaluation system, and they were plotted into4 grades (every grade included upper limit), and selected 5 excellent cultivars with high ornamental value and strong environment adaptability.The studies resolved all problems proposed in the subject. Propagation technical system was established. Cold hardiness of 15 Hibiscus syriacus was tested and their comprehensive qualities were appraised. |
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