Chromosome Karyotype Analysis of Allium fistulosum L.var.caespitosum Makino
In order to explore the karyotype characteristics of Allium fistulosum L.var.caespitosum Makino,the chromosomal films of root tip cells of 3 Allium fistulosum L.var.caespitosum Makino were obtained by the drop slice technique,and the karyotype analysis was performed.The results showed that all the three Allium fistulosum L.var.caespitosum Makino were diploid and the number of chromosomes was 2n=2x=16.The chromosome of Pingba white Allium fistulosum L.var.cae-spitosum Makino was shorter and nearly elliptical than that of Hezhang black Allium fistulosum L.var.caespitosum Makino and Hezhang red Allium fistulosum L.var.caespitosum Makino.The karyo-type formula of Hezhang black Allium fistulosum L.var.caespitosum Makino was 2n=2x=14 m+2 sm.Among the 16 chromosomes,those with arms ratio greater than 2 accounted for 12.5%of the to-tal number of chromosomes,the karyotype asymmetry coefficient was 59.16%,and the karyotype type was 2A.The karyotype formula of Hezhang red onion was 2n=2x=12 m+4 sm.Among the 16 chromosomes,those with arms ratio greater than 2 accounted for 12.5%of the total number of chro-mosomes,the karyotype asymmetry coefficient was 59.16%,and the karyotype type was 2A.The karyotype formula of Pingba Allium fistulosum L.var.caespitosum Makino was 2n=2x=14 m+2 st.Among the 16 chromosomes,the chromosome with arm ratio greater than 2 accounted for 12.5%of the total number of chromosomes,the karyotype asymmetry coefficient was 57.10%,and the karyo-type type was 2A.Among the three varieties,Hezhang red Allium fistulosum L.var.caespitosum Makino was the most evolved,while Pingba white Allium fistulosum L.var.caespitosum Makino was the least evolved.