This research evaluated the following fiber properties (determined by HVI): upper half mean length (UHML) defined by mean of the longest 50% of the fibers in mm of a sample of cotton; fiber strength (FS) defined by fiber bundle strength in gf/tex; fiber length uniformity (FU, %); and elongation of fibers at break (EL, %).
To serve as a reference, mean data of LP (%) and UHML of the parents were taken in assays of lines and cultivars conducted in different environments in the Brazilian Cerrado region (Table 1).
Table 2 shows a difference between the Fjhybridsfor all traits, except for UHML, which evidences the variability among [F.sub.1] hybrids.
The opposite occurred for UHML, i.e., the fiber length was higher when using parent A than when using parent B (Table 3).
Even when the UHML values in hybrids are higher than 33 mm, if the parent of group II is the low-fiber A parent, the [F.sub.1] hybrids will exhibit lower lint percentage values.
However, UHML is a fiber quality trait that still requires further research.
Caption: Figure 1--Genotypic correlation network between the variables lint percentage (LP), upper half mean length (UHML), fiber uniformity (FU), fiber strength (FS), and elongation (EL) evaluated in 18 cotton [F.sub.1] hybrids.
The highest [h.sup.2]s were for fiber length (UHML: 0.70: ML: 0.58) and fineness (H: 0.65; Hs: 0.57).
The strongest correlations consistently observed within the three data sets related ML to UHML (0.97 on average), IM to H (0.89) and to MR (0.83), and Rd to +b (-0.74), and (only in the B[C.sub.2][S.sub.1] data set) H to Hs (0.76).
For simplicity, we will hereafter consider certain traits as groups of related or correlated traits: length components (LEN), grouping the two variables ME and UHML, maturity/fineness components (FIN), grouping the 4 variables IM, MR, H, and Hs, and color components (COL), grouping the two variables reflectance, Rd, and yellowness index, +b.