Karyomorphology of Amaryllis Hybrids

Abstract

Karyotype analysis, genome analysis and development of gametophytes is described for nine hybrids of garden Amaryllis. The basic chromosome number is x=11 and all nine hybrids are tetraploid with a bimodal distribution favoring long and short lengths. The basikaryotype proposed by Narain and Khoshoo (1968) which consists of two median, five submedian and four subterminal chromosomes, is not traceable in any of the nine hybrids. 2A5SM4M and 4A4SM3M are the most common basikaryotypes in six out of nine hybrids. All hybrids show altered karyotypes. Chromosomes range from 4.3-17.7μm in length. The total chromatin ranges from 307.6μm-502.5μm. Bivalents, trivalents and quadrvalents are formed during meiosis. About 20-40% of the pollen grains are sterile. Development of the megagametophyte is monosporic in 90% of the ovules and bisporic in the remaining 10%. All nine hybrids show 80-90% degeneration of embryo sac at various stages of development. The fruiting behaviour and low percentage of seed set are associated with pollen sterility, and degeneration of embryo sacs.