Study On Reproductive Biology And Tissue Culture Technology Of Rhododendron Cultivars

Rhododendron is beautiful,colorful and has high ornamental value.It is one of the top ten famous flowers in China and one of the best-selling Chinese New Year’s Eve flowers.However,there are still some problems in the market such as the limited cultivars and short market supplies.Therefore,it is particularly important to promote the introduction of excellent Rhododendron cultivars and accelerate the commercial production.Rhododendron‘Lvseguanghui’and Rhododendron‘Jinsichuiliu’are rare cultivars of Rhododendron.They have high ornamental and application value due to their beautiful flower colors,rare flower types and good resistance,which have broad market development prospects.This research elucidated the reproductive biological characteristics of Rhododendron‘Lvseguanghui’by analyzing its flowering phenology,flower morphological characteristics,pollen vitality and stigma receptivity,breeding systems and flower-visiting insects.The optimal disinfection time,optimal culture medium for each stage,and optimal transplant substrate for Rhododendron‘Lvseguanghui’and Rhododendron‘Jinsichuiliu’were also explored to establish the tissue culture and rapid propagation system.Results of the research aim to enrich the relevant research data of Rhododendron,and provide theoretical basis for the introduction,domestication,popularization and commercialization of excellent Rhododendron cultivars.The main conclusions are as follows:1.The flowering period of Rhododendron‘Lvseguanghui’was from end April to the middle June after its introduction to Shaanxi,and the single flowering period could last for26.50±3.11 days.The umbrella was terminal and there were 1～3 flowers on each inflorescence.The flowers were green at the beginning,and then turned white gradually,with green spots at the base.Most pistils were higher than the stamens.The pollen vitality of Rhododendron‘Lvseguanghui’was not measured in the experiment.This indicated that there may be male infertility in Rhododendron‘Lvseguanghui’.The stigma was receptive at the bud stage,which was strongest at the initial and full flowering stages.The breeding system of Rhododendron‘Lvseguanghui’was outcrossing,partially self-incompatible and pollinators needed.The major flower-visiting insects of Rhododendron‘Lvseguanghui’were Hemiptera bugs,Diptera flies,Hymenoptera ants,Coleoptera beetles and Arachnids.They all began to visit flowers after the temperature rises.There were almost no flower-visiting insects in rainy days.2.The buds of Rhododendron‘Lvseguanghui’and Rhododendron‘Jinsichuiliu’as explants were taken from March to April.The best disinfection method of Rhododendron‘Lvseguanghui’and Rhododendron‘Jinsichuiliu’was 70%alcohol disinfection 30s and then0.1%Hg Cl₂ disinfection for 5min.The optimum multiplication medium of Rhododendron‘Lvseguanghui’was WPM+TDZ 0.5mg/L+NAA 0.05mg/L,and the survival rate was 10.85after been inoculated 90 days.The optimum multiplication medium of Rhododendron‘Jinsichuiliu’was WPM+TDZ 0.5mg/L+IBA 0.3mg/L,and the survival rate was 9.75 after been inoculated 90 days.The optimum rooting medium for Rhododendron‘Lvseguanghui’was 1/2WPM+IBA 0.75mg/L+NAA 0.15mg/L.After 90 days,the average number of roots was 16.30,and the rooting rate was 83.33%.The optimum rooting medium for Rhododendron‘Jinsichuiliu’was 1/2WPM+IBA 0.5mg/L+NAA 0.15mg/L.After 90 days,the average number of roots after 90 days was 5.24,and the rooting rate was 83.33%.The most suitable substrate for transplanting the two Rhododendron cultivars was vermiculite:perlite=1:1.At this time,the transplanting survival rate were 90.00%and 83.33%respectively,but the transplanting seedlings grew better in the medium containing peat.Therefore,the transplanting seedlings can be moved to the substrate containing peat after they survive.