Low-Temperature Acclimation of Barley Cultivars used as Parents in Mapping Populations: Response to Photoperiod, Vernalization and Phenological Development.
A. E. Limin, A. Corey, P. M. Hayes and D. B. Fowler

ABSTRACT

Six barley (Hordeum vulgare L.) accessions, previously used as parents of mapping populations, were evaluated for characters potentially aVecting the location of low-temperature (LT) tolerance QTLs. Three were of winter growth habit (Kompolti Korai, Nure, and Strider), one was facultative (Dicktoo) and two were spring (Morex and Tremois). Final leaf number (FLN) and LT₅₀ were determined at weekly intervals from 0 to 98 days of LT acclimation/vernalization under both long day (LD) and short day (SD) photoperiods. The point of vegetative/reproductive transition was determined from measurements of double ridge (DR) formation and FLN. With the exception of Nure, SD delayed development by increasing leaf production. Dicktoo was extremely SD sensitive lengthening its vegetative phase by more than 63 days relative to the LD photoperiod. SD had the opposite eVect on Nure, causing an accelerating of Xowering exhibiting the characteristic of 'short day vernalization'. All accessions except Dicktoo and Kompolti Korai acclimated rapidly in the Wrst 7 days of LT exposure, approaching their maximum LT tolerance in 14-21 days. Dicktoo and Kompolti Korai continued to slowly acclimate until reproductive transition. The results emphasize two important points: (1) the location of QTLs for LT tolerance, and as a consequence the identiWcation of putative candidate genes, will be a function of the genotypes sampled, the experimental conditions used, and the quality of the phenotypic data and (2) the barley LT tolerance pathway reaches an early impediment relative to closely related more hardy members of the Triticeae such as wheat and rye.

Keywords

Low-temperature tolerance, Phenotyping, Photoperiod, Plant development, Hordeum vulgare L, Mapping populations, Vernalization

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