Response to selection for the timing of vegetative phase transition in a maize population

Abstract

Variability for the timing of transition from juvenile to adult vegetative phases in maize (Zea mays L.) is genetically regulated and has been associated with disease and pest tolerance. Epicuticular wax is present in juvenile leaves and absent in adult leaves. The objective of this work was to assess the potential modification through selection of the timing of vegetative phase transition. Three cycles of divergent phenotypic selection for early and late vegetative phase transition performed on a synthetic population were evaluated by means of a randomized complete block design with two replications, in two locations of northwestern Spain across two years. Selection for early transition was made by recombining plants with fewer leaves with epicuticular wax, while, for late transition, plants with more leaves with epicuticular wax were recombined. Selection response was significant and more efficient for late phase transition than for early phase transition. Other changes observed cannot be considered correlated responses to selection because they changed in the same way for both directions of selection. We conclude that selection for the timing of vegetative phase transition was efficient and there was no detrimental correlated responses on any agronomic trait.