Genotypic differentiation in temperature requirements for stratification in subtropical peach seeds

Abstract

The variability of species under local ecosystems, particularly in response to temperatures during endodormancy, permits adaptation of temperate fruit trees to subtropical climates. Information about the behavior of endodormant fruit trees and seeds is based on a narrow genetic base from higher latitudes. This work was conducted to generate information about responses of endodormant seeds from several subtropical peach (Prunus persica L.) genotypes, as a basis for breeding and selection in these regions. Samples of peach seeds were collected from genotypes originating at a range of altitudes in tropical-subtropical regions to evaluate their responses to different temperatures and lengths of stratification periods. When seeds were stratified at 7 °C, some genotypes with very low-chilling requirement registered a high percent germination in <40 days, and all accessions studied reached 95% germination before day 80. When seeds were stratified at warmer temperatures (10 and 14 °C), germination started earlier and was high at 10 °C for most accessions. Although seeds of some late-blooming accessions germinated earlier at 10 or 14 °C than at 7 °C, percent germination was lower and time-response curves were flatter. This contrasts with previous reports on genotypes with high-chilling requirement, where no germination was registered at 14 °C. These observations provide a background for screening seedlings for adaptation to local conditions, and suggest that endodormancy models should he based on information generated from local genotypes when applied in subtropical regions.