Genetic gains in agronomic and technological traits of elite cotton genotypes

Abstract

The objective of this work was to estimate the predicted genetic gains with the simultaneous selection of agronomic and technological traits from elite cotton lines using selection indexes. Data from the evaluation of 36 elite lines were evaluated in three trials located in Apodi-RN in 2013 and 2014 and Santa Helena, GO, Brazil in 2013, in a randomized block design with two replicates. The agronomic traits evaluated were: plant height (PH), average boll weight (ABW), percentage of fibers (PF) and seed cotton yield (YIE). In 20 bolls from each experimental unit, the following technological fiber traits were evaluated: fiber length (UHM), fiber uniformity (UNIF), short fiber index (SFI), fiber strength (FS), elongation (ELON), micronaire (MIC), reflectance (RD) and degree of yellowing (+b). Smith and Hazel, Pesek and Baker and Mulamba and Mock selection indexes were tested for selection of the seven superior genotypes, assigning the coefficients of genetic variation (CVg) as economic weight. There were no interaction between genotypes and environments for any of the evaluated traits. Smith and Hazel index resulted in negative gains for fiber length and positive for the traits whose reduction is of interest, such as plant height, micronaire and degree of yellowing. Pesek and Baker index provided positive predictive gains for all traits of interest. However, it promoted reduction only to the degree of yellowing. Mulamba and Mock presented satisfactory gains, being the most suitable for selecting genotypes aiming at simultaneous gains in yield and fiber technological components.