MSc

The present investigation on “Assessment of variability and compatibility in Tagetes spp.” was carried out in the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, during 2006 – 2007. The experimental material consisted of 14 accessions of African marigold and seven varieties of French marigold, collected from Andhra Pradesh, Karnataka and Kerala.
The major objectives include assessment and interpretation of genetic variability and the inter relationship between different traits, investigation of the reproductive biology and compatibility behaviour between different genotypes, formulation of an efficient selection method for identifying superior genotypes, estimation of the heterotic potential as well as characterization of superior hybrids at biochemical and molecular level along with their parents.
A local cultivar from Kapugal (Ka) in Andhra Pradesh had maximum flower yield of 114.69g per plant. On an average, it produced 24.66 flowers per plant with maximum fresh weight of flowers (4.64 g) and flower diameter (4.11 cm). It was closely followed by the accession collected from Ananthagiri (A) (Andhra Pradesh) with an average flower yield of 113.54g per plant. For this accession the number of flowers (31.16) and flower diameter (4.51 cm) were higher than Ka. In French types variety French vanilla had the highest flower yield (29.76 g per plant), followed by Boy O Boy (27.13 g per plant).
Highest genotypic and phenotypic coefficients of variation were observed for the character number of whorls of ray florets followed by yield per plant. Heritability and genetic gain were maximum for the characters such as number of whorls of ray florets, fresh weight of flowers, yield and plant height. Correlation studies revealed the traits number of flowers per plant and fresh weight of flowers had strong correlation with yield. Comparison of different genotypes based on the selection index value revealed the superiority of genotypes Kapugal (Ka) followed by Ananthagiri (A) and Thammara (T). The 14 genotypes were grouped into five clusters based on genetic distance. Reproductive biology and compatibility studies showed that there was no self or cross incompatibility in African marigold but in inter specific hybridizations with French types, seed set and germination was lower.
Six superior hybrids Th-1 X C-6, Tr-5 X Pil.O-3, Th-6 X Ka-3, Th-1 X A-3, Vk1-5 X Pil.O-4 and Tr-3 X Vk2-3 for the characters plant height, number of whorls of ray florets, number of flowers, fresh weight of flowers and flower yield were selected based on heterobeltiosis and relative heterosis values. There was no much difference between direct and reciprocal crosses except for the character seed set percentage. Biochemical analysis of the selected hybrids and parents for total carotenoid content showed that overall mean of parents was 5.56 mg and that for the hybrids it was 5.54 mg per one gram of fully opened flowers.
Molecular characterization of the selected hybrids and parents produced a total of 20 bands with three primers, The bands of approximate size 1375 bp and 1584 bp were present in all the parents whereas 1904 bp band was found in all except Th-6 and A-3. Similarly the bands of approximate size 1375 bp and 1584 bp were shared by all the hybrids except two and 1904 bp was present in all the hybrids except three.