Screening Of Good Quality Germplasm Of Corylus Heterophlla And The Research On Its Propogation Technique

Corylus heterophlla is a perennial,deciduous shrub or small tree,which distributes widely in China,and has economic value,ecological value,and ornamental value.In China,wild types and their seeding populations were usually used to establish C.heterophlla orchard.Low yield,poor quality and the lacks of systematic evaluation of economic traits and selective breeding of excellent speices have significantly hampered the development of C.heterophlla industry.On the other hand,C.heterophlla is frequently reproduced by seeds,and this method has a negative effect on maintaining good characters of the maternal parent.Previous researches showed that mound layering and soft cutting were the suitable asexual reproduction methods for species of Corylus;however,a mature technology system of vegetative propagation of C.heterophlla has not been established.This study,on one hand,was conducted on C.heterophlla at the age of 2 to 6.Scores were assigned to each economic indicator,including nutweight,kernel rate,shape index,shell thickness and yield.The comprehensive score of each plant were calculated for the purpose of selecting excellent single plant and provide foundation material for further selective breeding research.On the other hand,the optimal IBA concentration for rooting was selected by applying three different concentrations of IBA to C.heterophlla.And rooting patterns of mound layering of three species,C.heterophylla,C.avelana and Hybrid Hazel(C.heterophylla × C.avellana)were compared.Moreover,the optimal soft cutting criterias were selected by investigating the effects of different aspects on soft cutting rooting.Meanwhile,the difference of soft cutting rooting patterns between three species of Corylus was compared.The above research could provide technical support for asexual reproduction(layring and cutting)of C.heterophlla.Main research results are listed below:1.Selection of good quality germplasm of C.heterophyllaThe research was conducted on 95 hazelnut trees at the age of 2 to 6,which naturally distributed in Tieling district of Liaoning province.Comprehensive evaluation was performed on 59 cultivars in 2013,and 36 cultivars in 2014,in terms of their nutweigh,kernel rate,shape index,shell thickness and yield.The observations of the comprehensive indicator of good cultivars were ordered from high to low,and top 10 with scores higher than 75 were selected in both years.Based on the analysis of individual economic indicator,nine cultivars were selected as the first bunch of breeding subjects:XF-3,TL-3,CT-1,TL-9,TL-26?TL-25,TL-24,XF-5 and CT-8.These cultivars can be used for further selective breeding research.2.Research on layering reproduction technique of C.heterophllaThe research was conducted on current 5-year-grown scions of C.heterophylla.Applying 1000,1500,and 2000 mg·L-1 IBA to C.heterophylla for mound layering experiment,the resurt showed that the optimal IBA concentration was 1000?1500 mg·L-1,the rooting rate of C.heterophlla reached at 88.2%?88.4%.The effect of 1500 mg·L-1 IBA on rooting of Current 5-year-grown scions of C.heterophylla,C.avelana and Hybrid Hazelnut,at the age of 5 years,were then compared in layering experiments.The rooting time required by C.avellana was the shortest(18 days),and the second shortest was by Hybrid Hazelnut,25days.And C.heterophylla required the longest rooting time,which was 30 days.The rooting rate of C.avellana was the highest,98.89%,followed by Hybrid Hazelnut,83.33%,and C.heterophylla,57.8%.3.Research on soft cutting propagation technique of C.heterophllaThe effect of different concentrations of IBA,different shoot segments,cutting time,and saving leaf amount on rooting of cuttings of hazelnut were compared in the greenhouse equipped with cooling and high pressure micro mist system.The results showed that the best timing for cutting in Tieling area is the mid June;Better rooting results from cutting upper branches as the lower cutting shoot;the optimal IBA concentration for upper cutting shoot is 1500 mg·L-1 with rooting rate at 46.43%;the optimal IBA concentration for lower cutting shoot is 2100 mg·L-1 with rooting rate at 19.06%;The rooting result was the best when left one piece of whole leaf(29.4%),followed by left with two half leaves(22.3%).All the above results indicate that soft cuttings propagation will be one of high efficient propagation methods applied in praction in the future.Moreover,the difference between these 3 species of Corylus in rooting time under the same level of IBA was compared.The upper branches were the easiest part to root with the shortest rooting time,followed by the middle branches of the cuttings and the lower branches.C.avellana was the easiest hazelnut to root and produce callus and root in the shortest time,followed by Hybrid Hazelnut,C.heterophylla.