Studies Of Collection And Utilization Of Some Viburnum L. Germplasm Resources

Viburnum L.belongs to Caprifoliaceae,which has a main distribution of East Asia and North America.There are about 800 species in Viburnum L.all over the world and 80 species in China.Though consulting interrelating documents,the study analyzed ornamental characteristics of Viburnum L. germplasm resources of China comparing with the investigation results of Gansu,Chongqing and Chengdu districts.Some Viburnum L.plants with excellent ornamental characteristics were collected on the basis of overall investigation on Viburnum L.germplasm resources in Tai'an City centering on one-hundred-year old Viburnum macrocephalum which grew on Orhat Cliff of Mt.Tai.At the same time,some species and cultivars with excellent ornamental characteristics were introduced.Seven Viburnum L.were initially screened which could grow naturally in Tai'an and be suitable to garden application on the basis of the study of biological characteristics. Crossbreeding and propagation techniques were also carried out with initial screened Viburnum L.Rapid propagation techniques of seven Viburnum L. plants mastered systematically.The study not only enriched Viburnum L. germplasm resources in Tai'an,but provided scientific basis for guiding peasants to cultivate Viburnum L.seedlings with high quality.The main results are as follows:1.The resources of Viburnum L.were divided into the flowering type,the leaf type and the fruiting type in terms of ornamental parts.Eight Viburnum L. plants were determined for the study on the basis of the collection and introduction of germplasm resources with good quality.Though observation of outdoor cultivation tests,using a standard of adaptation to climatic features of Tai'an and achievement of expected ornamental effects by taking simple measures in winter,the study determined initially seven Viburnum L.suitable to Tai'an.They were Viburnum macrocephalum,Viburnum macrocephalum f. keteleeri(Carr.) Nichols,Viburnum plicatum Thunb.,Viburnum sargentii Koehne var.calvescens Rehd.,Viburnum 'dina',Viburnum rhytidophyllum Hemsl.,Viburnum odoratissmum var.awabuki.2.Though the observation of biological characteristics of seven Viburnum L.,the growth features and ecological characteristics were studied.At the same time,the reaction to prunning were also observed by prunning tests. Biological characteristics showed that Viburnum L.such as Viburnum macrocephalum and Viburnum macrocephalum f.keteleeri(Carr.) Nichols which hidden buds in bottom branches had strong sprouting ability and had obvious trunk were suitable to tree-shape training and pruning.Viburnum L.such as Viburnum sargentii Koehne var.calvescens Rehd.which hidden buds in basal branched or hidden buds underground had strong sprouting ability were suitable to shrub-shape pruning.In order to achieve the best effects for the flowering type in ornamental seasons,pruning tests were made according to branches features of Viburnum macrocephalum.The results showed that it was extremely remarkable that pruning rate was controlled in 25%by thinning-branch method in late autumn;As far as Viburnum macrocephalum and Viburnum macrocephalum f.keteleeri(Carr.) Nichols,it was easy to reduce the amounts of flowering branches by pruning in the growing seasons from the middle June to the late August which resulted in the whole inflorescences were easy to frozen injured or be dead due to parts of inflorescences or flower buds blooming in Autumn.3.The propagation tests were carried out with initially selected Viburnum L.The results were as follows:The seeds of Viburnum macrocephalum f. keteleeri(Carr.) Nichols and Viburnum sargentii Koehne var.calvescens Rehd which were seed seedling need to be stored in winter for germination.The propagation by layers was not suitable for Viburnum L.production in garden nursery.The survival rate was more than 90%to use bud grafting in autumn to Viburnum macrocephalum and Viburnum 'dina' in grafting propagation.The best stem grafting in spring was stabbing-abdomen grafting and its survival rate was 68%.The best time for softwood cutting of Viburnum macrocephalum was from 25^th of June to 15^th of July.The effect of cutting rooting with 100mg/L ABT1^# and immersion time 5min was best and survival rate was 90.2%.4.Though the observation of the petals color changes and the size of petals in the process of inflorescences blooming of Viburnum macrocephalum, the author found that parts of flowers of Viburnum macrocephalum had stamens.Some hybridization seeds were obtained unexpectedly using pollens of Viburnum macrocephalum f.keteleeri and Viburnum 'Dina' with Viburnum macrocephalum respectively.This showed that pistils of Viburnum macrocephalum developed normally.The fact showed disparity with that of records of Chinese Trees.Whether the Viburnum macrocephalum in Orhat Cliff of Mt.Tai was a variety waits on further investigation and identification. The crossbreeding test made the varities improvement of Viburnum macrocephalum by conventional breeding become the possibility.