Playing with plant height and spike number in Brazilian wheat: an applied study on early-generation selection effects

Although genomic tools have proven to be very useful for plant breeding, most bread wheat breeding programs at developing countries still rely solely on phenotypic selection. Controversially, applied studies on this theme are gradually becoming scarce worldwide, especially the ones focusing on specific traits, such as plant height and spike number. The present study aimed to depict the genetic effects of selecting for both decrease and increase of plant height and spike number on a set of Brazilian wheat populations at early segregating generations, bringing information for the development of effective breeding strategies. Five populations in F 2 were subjected to five selection criteria, including no selection. Eight agronomic traits were assayed. Plant height has shown the highest broad-sense heritability coefficients, selection differentials, selection gain estimates, and real selection gains. On the other hand, the means for spike number for these parameters were low to moderate. Selection for these traits impacted on indirect selection gains for all other traits. Early selection for increasing both plant height and spike number per plant has positive effects on grain yield per plant and its components on the segregating populations assayed, according to selection gain estimates. The present germplasm does not allow for further plant shortening without losing yield potential.