Chromosome Number Variation in Ocimum basilicum L.

Meiotic analysis documented variation in chromosome number in Ocimum basilicum L. (family: Lamiaceae) in the form of 2n=72 chromosomes in O. basilicum var. citriodorum (lemon basil) and 2n=52 chromosomes (a new number in Ocimum) in variety crispum. Persistent presence of secondary association of chromosomes in 87.88% and 69.39% metaphase I cells of var. citriodorum and var. crispum respectively suggested secondary polyploid nature of the species. Statistical analysis of cytological data revealed x=12 as basic chromosome numbers for the varieties studied and polyploidy as well as aneuploidy might have been operative at different levels to give variable chromosome numbers within O. basilicum.