Sammanfattning

Background and Aims Biotic and abiotic stressors can cause different defoliation patterns within trees. Foliar pathogens of conifers commonly prefer older needles and infection with defoliation that progresses from the bottom crown to the top. The functional role of the lower crown of trees is a key question to address the impact of defoliation caused by foliar pathogens.Methods A 2 year artificial defoliation experiment was performed using two genotypes of grafted Pinus radiata to investigate the effects of lower-crown defoliation on carbon (C) assimilation and allocation. Grafts received one of the following treatments in consecutive years: control-control, control-defoliated, defoliated-control and defoliated-defoliated.Results No upregulation of photosynthesis either biochemically or through stomatal control was observed in response to defoliation. The root:shoot ratio and leaf mass were not affected by any treatment, suggesting prioritization of crown regrowth following defoliation. In genotype B. defoliation appeared to impose C shortage and caused reduced above-ground growth and sugar storage in roots, while in genotype A, neither growth nor storage was altered. Root C storage in genotype B decreased only transiently and recovered over the second growing season.Conclusions In genotype A. the contribution of the lower crown to the whole-tree C uptake appears to be negligible, presumably conferring resilience to foliar pathogens affecting the lower crown. Our results suggest that there is no C limitation after lower-crown defoliation in P. radiata grafts. Further, our findings imply genotype-specific defoliation tolerance in P. radiata.

Nyckelord

A/C-i curves; defoliation; biomass; growth; leaf area; non-structural carbohydrates; photosynthesis; Pinus radiata; root:shoot; foliar pathogens

Publicerad i

Annals of Botany
2020, Volym: 125, nummer: 6, sidor: 955-967
Utgivare: OXFORD UNIV PRESS

SLU författare

• Gomez-Gallego, Mireia

  • Institutionen för skoglig mykologi och växtpatologi, Sveriges lantbruksuniversitet
    
  • Auckland University of Technology (AUT)
  • Scion (New Zealand Forest Research Institute)

Associerade SLU-program

SLU Nätverk växtskydd


UKÄ forskningsämne

Botanik
Skogsvetenskap


Publikationens identifierare

DOI: https://doi.org/10.1093/aob/mcaa013

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/107220