Cytomorphological Studies in the Genus <i>Linum</i>

Abstract

With a view to finding out the inter-relationships between different 30 chromosome species of the genus Linum, 14 interspecific hybrids involving 8 species were obtained and studied morphologically and cytologically.The interspecific hybrids were studied for salient morphological characters of agronomic importance such as tillering, height, number of secondary branches, seed size besides hybrid vigour and seed fertility. They were also studied for their chromosome pairing and chiasma frequency in the pollen mother cells.The hybrids showed varying degrees of pollen sterility inspite of their chromosomes pairing and separating regularly. This indicated that the divergence of these species has progressed on either genic differentiation or cryptic structural differences. The species L. floccosum and L. palliscence differed from the rest in forming a single quadrivalent. This shows that these species differ from one another by a single reciprocal translocation.Based on chiasma frequency all the hybrids can be grouped into two categories, those forming more or less equal number of chiasmata as the parental species and those forming less than the parents. Suitable interpretations are advanced to explain the reduction in chiasma frequency in some hybrids under study. Probable cytogenetical mechanisms underlying species differeniation in the genus Linum are discussed.