Studies on multiple polyploids inNicotiana

A trispecific hybrid combination ofNicotiana glutinosa-trigonophyllatabacum was successfully colchicine doubled, and multiple polyploids were raised. Chromosome complement was full (96) in most of the plants. Three of the fifteen plants studied showed chromosomal elimination of varying numbers.Six plants showed floral modifications, each of a different type; of these two were associated with chromosome loss, others were attributed to genome-cytoplasm interaction, or to genetic factors.Pollen fertility was good in almost all the plants but no capsule was set on them. On some plants parthenocarpic fruits developed easily and capsules were quickly set when back- or out-crossed.Several quadruple hybrid combinations were obtained and their survival capacity is reported. Difficulties in establishing, and possibilities of successfully utilising the multiple polyploids for breeding work are discussed.An abstract of this paper has been presented at the 3rd Tobacco Research Worker's Conference held at Madras from 13th to 15th September, 1962.