Seasonal variations of auxin and gibberellin A4 levels in cambial-region tissues of three conifers (Pinus elliottii, Chamaecyparis obtusa, and Cryptomeria japonica) with inherently different wood densities

Abstract We previously reported the species-specific annual ring formation characteristics of three conifers (slash pine ( Pinus elliottii ), hinoki (Japanese cypress, Chamaecyparis obtusa ) and sugi cedar, Cryptomeria japonica )) grown in same stand over 2 years. found that affected inherent difference wood density among these > sugi). Plant hormones cambial-region tissues were believed to affect formation. However, seasonal variation amounts plant had only been examined a few tree species. In this study, as first step elucidating role conifers, we report variations auxin (indole acetic acid, IAA) gibberellin A4 (GA4) levels their effects on pine, hinoki, sugi) with inherently different densities. Sugi (small density) significantly higher IAA formed more tracheids early season than late season, although slash (large season. Hinoki (intermediate constant number throughout There significant positive correlations between during two conifer A close relationship was observed ratio (late/early season) density. No consistent trend change level transition from earlywood latewood recognized conifers. The pines those hinoki. GA4 no effect These results suggest patterns might lead differences through rings.