1982 Volume 47 Issue 3-4 Pages 737-742
Chromosome pairing was studied in pollen mother cells (PMC) of the interspecific hybrids (2n=36) in Tagetes patula (2n=48) and T. erecta (2n=24). Among the 16 configurations of chromosomal pairing observed, the configuration with 12 bivalents plus 12 univalents was most frequently seen (30.56% of the PMC). A maximum of 15 bivalents was observed in a cell indicating some degree of intragenomal pairing in the hybrids. Trivalents and quadrivalent were present in 56.95% of the PMC, and 7.17% of the 36 chromosomes was involved in multivalent for-mation. In average, there were 10.97±0.20 univalents, 11.22±0.15 bivlants, 0.75±0.10 trivalent and 0.08±0.00 quadrivalent per cell. Laggards were very frequently seen (84.28% of the PMC). Pollen viability was 13.6% partly due to meiotic irregulatities. Seed fertility was very poor and physiological incompatibility may be considered a factor for the low fertility of the interspecific hybrids. The origin of T. patula is discussed.