Backcross Techniques in Transferring Insect Resistance and Good Fiber Qualities to Naturally Colored Cotton

Abstract

The backcross method was used to transfer traits of resistance with regard to some cotton insects and the good fiber qualities of Salid 1 (SD1) and 413, the recurrent parents, respectively, to naturally colored cotton varieties, the non recurrent parents, (Green, Dark Green, Brown and Red Brick). The experiment was conducted at Suwan Farm, Nakhon Ratchasima from 2002 to 2006. Both the parent types and backcross progenies (SD1green, SD1dark green, SD1brown and SD1red brick) obtained were compared in terms of yield, fiber qualities and hopperburn rate during 2006 to 2008. The results indicated that in 2006, all backcrosses gave significantly lower seed cotton yields than those of their recurrent and non recurrent parents, except SD1green and SD1brown. In 2007, only SD1 red brick had a significantly higher yield than that of its non recurrent parent, Red Brick. There were no significant differences in terms of 2008 agronomic performance among all parents and the backcrosses. The high volume instrument (HVI) average results showed that all backcrosses, except SD1 413, had the fiber length determined as short. Fiber strength (g/tex) of each backcross also expressed better results than that of its recurrent parents. Only SD1 redbrick showed improved fiber elongation compared with its non recurrent parent, though it was only slight. The naturally colored cotton varieties, Brown and Dark Green, were significantly lower than their progenies, SD1brown and SD1 dark green, in terms of leafhopper numbers, during the years 2006 and 2007, respectively. In 2006, all backcrosses had a hopperburn rating slightly better than that of both their parents. The 2007 ratings of most backcross progenies were equal to the parents, except for SD1 green and SD1 brown, which were better.