Inheritance and heterosis of important traits in some crosses of cotton (gossypium spp)

This study was conducted in the Agricultural Research Corporation, (ARC) at the Gezira Research Station, Gezira State, Wad Medani, Sudan, latitude (14 deg C- 24 deg C N) longitude (33 deg C- 29 def C E) for the two seasons (2004/05 and 2005/06). The objectives were: (a) to investigate heterosis (hybrid vigor) in the F1 generations for production of hybrid cotton, and (b) to investigate the inheritance of glandless ness and other desirable traits in F2 generations from interspecific crosses between the glanded cotton variety Barakat-90,(G.barbadense), as female, and the glandless lines GLIA and GLIB (G.hirsutum) as males. The major intention from the latter was to help in the breeding of cotton varieties with no/or low gossypol content in the seeds for the consumption of monogastric animals, and possibly humans. The experiment was laid out in randomized complete block design with three replications in season 2004/05 and four replications in season 2005/06. On the other hand, the F1 generations were selfed in season 2004/05 and the two F2 populations were raised in season 2005/06 in order to investigate inheritance of the selected traits.The analysis of variance showed highly significant variability for all of the measured traits between the two F1 generations and their parents. The two interspecific F1 generations (FlA, F1B) were leading in number of bolls per plant giving a range of 38.27-42.71. They were also leading in seed cotton yield (Sc) and ranged between 2614.4 2624.3 Kg/ha. They also recorded higher values for all of the fiber traits in the two seasons. They showed intermediate values between their parents, with values closer to the G. hirsutum than the G. barbadense parent on the earliness traits. The estimate of mid and better parent heterosis for the two F1 generations (FlA,F1B) showed increase in hybrid vigor in the economic traits such as number of boll per plant in which case the FlA recorded values of 90.02 and 152.77 (%) better and mid parent heterosis over the two seasons combined data analysis. The F1B also gave values of 112.07 and 194.55 (%) better and mid parent heterosis. With respect to seed cotton yield the two F1 generations were also superior over their parents, FlA giving better and mid heterosis of 33.89 and 55.01 (%) and F1B giving 15.53 and 41.73(%) over the two seasons combined analysis. The two F1 generations also recorded positive and significant better and mid parent heterosis for all of the fiber traits. The seed cotton yield was highly and positively correlated with some of its components and with plant height. It also showed positive correlation with some fiber quality traits (length, strength and uniformity ratio (UR %)).However, it showed highly significant negative correlation with most of the earliness traits. As for inheritance the F1 data showed that the glandlessness trait is controlled by recessive genes and the F2 segregation ratios showed the expression of this trait on different parts of the plant is controlled by different sets of allelomorphic genes. The inheritance of other selected traits, namely: color of the plant body, leaf spot, hairiness, corolla color and fuzzy seed coat were in most cases simply inherited by one or two genes. The individual characters are discussed in the manuscript for both F2A and F2B.In addition, Barakat-90 and GLIA and GLIB could be identified as suitable parental lines for hybrid cotton production