**3. Cytological analysis**

The chromosome pairing at metaphase I of meiosis was studied. The calyx and corolla were removed and floral buds were fixed overnight in 96% alcohol and acetic acid (7:3). Buds were kept at room temperature for 3 days, immersed in fresh fixative and stored in a refrigerator. They were examined for meiotic associations in the pollen mother cells (PMCs) using iron acetocarmine squash technique [30]. The analysis of chromosomal changes was carried out on the basis of M I associations at the first meiosis. The development of PMCs was examined at the tetrad stage for each plant. The meiotic index was calculated as the percentage of tetrads whereas pollen fertility was estimated by acetocarmine staining.
