Alternative Methods for Determination of Ploidy Level in Chamomile (Chamomilla recutita(L.) Rausch.) Breeding

Abstract

A comparative examination of certain morphological characteristics of chamomile provided the possibility of determining ploidy level at different stages of plant development as rapidly and as accurately as the classical chromosome counting. Pollen grains from diploid plants had only 3 germpores, while pollen from tetraploid plants generally had 4 and only a few (2.3%) were a mixture of 3 and 4 germpores. The lowest number of chloroplasts for tetraploid plants was 23 per pair of guard cells, while the highest number of chloroplasts for diploid plants was 22 per pair of guard cells. The highest number of stomata in the tetraploid plants was 11.7/mm2 and the lowest number for the diploids was 31.2/mm2. Overlapping characteristics that could not be used in determining ploidy level included length of stomatal guard cells, diameter of pollen grains, width, number, and length of ligulate flowers, weight of 100 flower heads, and height of plants. The number of pollen germ pores, stomata, and chloroplasts, however, provided a distinct, accurate, rapid, and convenient identification method for tetraploid and diploid chamomile in various stages of plant development.