Cytology And Technology Of Chromosome Doubling Of Alnus Cremastogyne Burk And A.formosana

Alnus cremastogyne Burk and A.formosana belong to the Alnus Betulaceae.There were little research on those genetic improvement. In order to meet the increasing requirement of wood production in China, it is necessary to make a genetic improvement program on A.cremastogyne and A.formosana.Meiosis of pollen mother cells (PMCs), megaspore mother cells (MMCs), development process of embryo sac and chromosome doubling of pollen of A.cremastogyne and A.formosana were studied.PMCs started to meiosis during late September and lasted approximately 9 to 18 days in A.cremastogyne, and discrepancy of the starting time in meiosis stages is about 13 days. PMCs started to meiosis during late September and the process of meiosis lasted approximately 7 to 12 days and and discrepancy of the starting time in meiosis stages is about 20 days in A.formosana. Asynchrony of meiosis was found among clones which result from interaction between genetic and environmental conditions.The meiosis stage of PMCs of A.cremastogyne and A.formosana appeared to have a major association to the length, diameter and color of flower bud.Preliminary research on pollen chromosomes doubling by colchicine was carried out and 2n pollen grains were obtained after treatment. The frequency of 2n pollen between different treatment periods, concentration of colchicine and treatment times had a significant difference in 2n pollen induced of A.cremastogyne. The highest average percentage of 2n pollen was 41.61% by treating flowers for 36h with 0.8% colchicine in pachytene. The average percentage of 2n pollen of A.formosana from different treatment periods, concentration of colchicine and treatment times had not significant difference. The highest average percentage of 2n pollen was only 13.50%, which may be result from deficiency of effective dosage in colchicine.Although Pollen mother cells started meiosis in a long time before that of the MMCs, the meiosis stages of PMCs and MMCs had close correlation during their development. The meiosis of MMCs and development process of embryo sac also appeared to have a major association to the length, diameter and color of flower bud. So according to the corresponding correlation between the meiosis stages of PMCs and MMCs and external features of the female flower bud, the meiosis stage of MMCs or development process of embryo sac could be determined instantaneously in chromosomes doubling of megaspore.