Strategies for the recurrent selection program in tobacco breeding for green leaf yield

Abstract

In conducting a recurrent selection (RS) program in tobacco (Nicotiana tabacum L.), inbred and noninbred progenies as well as double-haploid (DH) progenies can be used. There is also the possibility of recombining the selected progenies using half-sib (HS) or full-sib (FS) progenies. To choose the best RS strategy, the breeder's equation can be used. When using inbred progenies with an allelic frequency other than 50%, one of the genetic variance components is the genetic covariance between additive effects and homozygous dominance effects (D1). This component may present negative values and is part of the numerator in the equation for gain from selection (GS). Thus, the objective of this study was to estimate the genetic variance components in a tobacco population and compare the different strategies to conduct RS. From an RS population, HS, FS, and S1:2 inbred progenies were evaluated in different experiments. The dominance variance was null. In this condition, the estimate of D1 is not significant, meaning that D1 does not influence the GS in the RS program. With the obtained estimates, the GS was estimated for the seven different strategies for conducting the RS program. The use of DH lines in tobacco RS represents the best strategy. Other strategies allow expressive GS, such as the alternate use of inbred and FS progenies, for evaluation and FS progenies for recombination.