The Preliminary Study On The Cross Breeding Between Betula Alnoides With Betula Luminifera

Betula alnoides and Betula luminifera are deciduous arbors,which belong to Betulaceae,Betula.They are excellent fast-growing local hardwood species in tropics and south subtropics of China.Taking Betula alnoides and Betula luminifera as the research object,the pollen collection,storage, activity detection for pollen,artificial pollination,and the seedlings of progeny test are studied.The main results were summarized as follows:1.Late February is the best time for collecting pollen of Betula luminifera, to do pollination as bract and stigma morphology on the female inflorescence in the middle of march,to collect seed in may.2.The suitable temperature for germination is 30°that Betula luminifera pollen is in vitro germination;the sucrose concentration is 10%which is best for germination;taking 10%sucrose medium as the base,we test which 200mg.L^-1boric acid and 300mg.L^-1Ca are best.Though orthogonal experiment considering sucrose,B and Ca,we can make a decision that the best medium for germination of Betula luminifera in vitro is 10%sucrose, 200mg.L^-1boric acid mixed 200mg.L^-1Ca(NO₃)₂.3.Using the mixed pollen is to test germination characteristics of Betula luminifera pollen,germination rate and pollen tube length are increasing as the time passing,separately 4 and 6 hours later,becoming stable.So using the most suitable medium,at 30℃,4 hours later,we test the activity of Betula luminifera pollen.4.Compare the three methods for quickly testing the pollen activity, which are TTC,I-KI and aceto carmine.TTC method is the best for testing the activity of Betula alnoides pollen,the staining solution pH has better be 7.0,the result does not have the significant differences with the germination in vitro method.5.The 1000-grain weight of artificial pollination seed has the significial difference(P＜0.01),having the same maternal trees,different paternity or having the same paternity,different maternal trees.The germination experiment shows that fine sand is better than filter paper as the medium.The result in the seeding stage shows that the seeding grows slowly during the early stage,after sowing four months,the seedling height is only 3cm,later grows quickly.after sowing five months,the seedling height is 14cm,after sowing six months,the seedling height is as high as 40 cm,every cross combination are the same.6.By analysing the variation of foliar phenotype,the variation with the different maternal trees is more significant than that with the same maternal trees in the length,the width,the length to width ratio,the basic angle of leaf, the distance of the base width,and the petiole length.The variation of the length to width ratio is the smallest,the average coefficient is about 0.03,the variation of the distance of the base width,and the petiole length is the most significant,the average coefficient is about 0.07.7.By cluster analysis for the cross combination with the same maternal trees,as the data of foliar phenotype,we will find the offspring whose pollination is controlled by human phenotype has the significant difference with the comparation.Because the data belong to the seedlings of progeny test,we must continue to carry out the afforestation research to determine the hybrid effect,also must further carry on the molecular examination to each combination adult plant sample and the research of hybrid reliability.