Morphogenetic analysis of colchitetraploids in Impatiens balsamina L.

Abstract

Impatiens is a widely cultivated ornamental plant, belonging to family Balsaminaceae. Nearly 91% of Indian species of Impatiens are endemic. Impatiens balsamina L. also known as Gulmehndi is one of the popular species of North India. For further improvement of this plant, induction of polyploidy was undertaken. Induction of au- totetraploidy was successfully achieved in I. balsamina L. (Purple variety) using 0.4% colchicine, by apical shoot tip treatment of young seedlings. The morphology, cytology, pollen fertility and seed setting of induced autotetraploids (2n=4x=28) and diploids (2n=2x=14) have been comparatively analysed during present investigation. The autotetra-ploids exhibited enhancement in leaf, flower and seed size and number of primary branches, however, these plants showed stunted growth, thick stem, delayed flowering and reduced pollen fertility. These autotetra-ploids offer scope of positive selection in subsequent generations. Meiotic studies of the autotetraploids revealed different combinations of uni-, bi-, tri- and tetravalente with tetraploid chromosome number. Occurrence of high frequency of bivalents has been discussed. Though meiotic abnormalities were observed in few pollen mother cells (PMCs) of autotetraploids, however, their frequence was very low and a high chiasma frequency per cell has been reported. This study enumerates the possible use of polyploidy in improvement of ornamental plants. © 2007 Taylor and Francis Group, LLC.