Localized stem heating from the rest to growth phase induces latewood-like cell formation and slower stem radial growth in Norway spruce saplings

Year: 2022

Authors: Giovannelli A., Mattana S., Emiliani G., Anichini M., Traversi ML., Pavone F.S., Cicchi R.

Autors Affiliation: – Istituto di Ricerca sugli Ecosistemi Terrestri (IRET), Consiglio Nazionale delle Ricerche, SestoFiorentino, Italy
– Istituto Nazionale di Ottica (INO), Consiglio Nazionale delle Ricerche, Firenze, Italy
– Istituto Protezione Sostenibile delle Piante (IPSP), Consiglio Nazionale delle Ricerche, SestoFiorentino, Italy
– Istituto per la Bioeconomia (IBE),Consiglio Nazionale delle Ricerche, SestoFiorentino, Italy
– Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, SestoFiorentino, Italy
– Laboratorio Europeo di Spettroscopie Non-lineari (LENS), SestoFiorentino, Italy

Abstract: Recent climate projections predict a more rapid increase of winter temperature than summer and global temperature averages in temperate and cold environments. As there is relatively little experimental knowledge on the effect of winter warming on cambium phenology and stem growth in species growing in cold environments, the setting of manipulative experiments is considered of primary importance, and they can help to decipher the effect of reduced winter chilling and increased forcing temperatures on cambium reactivation, growth and xylem traits. In this study, localized stem heating was applied toinvestigate the effect of warming from the rest to the growth phase on cambium phenology, intra-annual stem growth dynamics and ringwood features in Picea abies (L.)H.Karst. We hypothesized that reduced winter chilling induces a postponed cambium dormancy release and decrease of stem growth, while high temperature during cell wall lignification determines an enrichment of latewood-likecells. The heating device was designed to maintain a +5◦C temperature delta with respect to air temperature, thus allowing an authentic scenario of warming. Continuous stem heating from the rest (November) to the growing phase determined, at the beginning of radial growth, a reduction of the number of cell layers in the cambium, higher number of cell layers in the wall thickening phase and an asynchronous stem radial growth when comparing heated and ambient saplings. Nevertheless, heating did not induce changes in the number of produced cell layers at the end of the growing season. The analyses of two-photon fluorescence images showed that woody rings formed during heating were enriched with latewood-likecells. Our results showed that an increase of 5◦C of temperature applied to the stem from the rest to growth might not influence, as generally reported, onset of cambial activity, but it could affect xylem morphology of Norway spruce in mountain environments.

Journal/Review: TREE PHYSIOLOGY

Volume: 42      Pages from: 1149  to: 1163

KeyWords: cambial phenology, latewood formation, Norway spruce, warming, xylogenesis
DOI: https://doi.org/10.1093/treephys/tpab166