Monohybrid Mendelian segregation in an interspecific hybrid population of tetraploid x diploid Coffea species- part 2

Coffee possesses normal sexual propagation behaviour and exhibits various characters in a large population. The work on the extent of variation is very limited and not well understood. In this context a study was undertaken during 2008-2011 to study the monohybrid segregation pattern in F2 population of C. arabica cv. ‘Cauvery’x (C. congensis x C. canephora var. robusta) established at Coffee Research Sub Station, Chettalli, Kodagu District, Karnataka in the year 2002. The results revealed that coffee varieties grown under Indian conditions possessed dependent and independent characters. The dependent characters followed the independent assortment along with closely associated characters and expressed the phenotypes to varying degrees. Therefore, the frequency of occurrence of such phenotypes did not match with the expected frequency of these characters at high probability confidence level. The genetic behavior of independent traits exhibited the genetic segregation in accordance with the Mendel’s law of segregation and fit in to the monohybrid ratio of 3:1 and 1:2:1 with high level of hypothetical confidence (P≥0.50 up to 0.95). It was observed that the genes regulating the dwarfing effect for coffee bush, thin stem and primary girth, low primary numbers and short primary length characters were found to be dominant over tall type bush, thick main stem and primary shoot as well as more number and length of primary shoots.