Studies on Chromosome Number, Floral Characteristics and Fertility of Diploid and Allotetraploid Dendrobium superbiens

Abstract

Chromosome counts were performed on the root tip of Dendrobium superbiens. The diploid plant had only 38 chromosomes, but allotetraploid had 76 chromosomes. The number of flowers in a large diploid inflorescence was much more than those in the tetraploid. The tetraploid. The tetraploid plants had larger flowers than those in the diplioids and the average width, length and thickness of sepals, petals of both diploids and tetraploids plants were significantly different. The blooming period of allotetraploid flowers longer than diploid flowers in 8 days. The meiotic division in microsporocytes of diploids and allotrtraploids plants were normal except some microspore of diploid plants have two to five cells in one group resulting from abnormal division of microsporocytes. The growth of pollen tubes of diploid plants was slow and many of them did not germinate after 3 days, whereas those of allotetraploids were long and numerous on the third day. The fertility of tetraploid plants was higher than that of diploid plants. Numerous seeds of allotetraploid had perfect embryos.