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Does soil nitrogen influence growth, water transport and survival of snow gum ( Eucalyptus pauciflora Sieber ex Sprengel.) under CO 2 enrichment?
Author(s) -
ATWELL BRIAN J.,
HENERY MARTIN L.,
BALL MARILYN C.
Publication year - 2009
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2009.01949.x
Subject(s) - xylem , shoot , hydraulic conductivity , eucalyptus , nitrogen , soil water , horticulture , stomatal conductance , biology , root system , botany , agronomy , chemistry , ecology , photosynthesis , organic chemistry
Eucalyptus pauciflora Sieber ex Sprengel. (snow gum) was grown under ambient (370 µ L L −1 ) and elevated (700 µ L L −1 ) atmospheric [CO 2 ] in open‐top chambers (OTCs) in the field and temperature‐controlled glasshouses. Nitrogen applications to the soil ranged from 0.1 to 2.75 g N per plant. Trees in the field at high N levels grew rapidly during summer, particularly in CO 2 ‐enriched atmosphere, but suffered high mortality during summer heatwaves. Generally, wider and more numerous secondary xylem vessels at the root–shoot junction in CO 2 ‐enriched trees conferred fourfold higher below‐ground hydraulic conductance. Enhanced hydraulic capacity was typical of plants at elevated [CO 2 ] (in which root and shoot growth was accelerated), but did not result from high N supply. However, because high rates of N application consistently made trees prone to dehydration during heatwaves, glasshouse studies were required to identify the effect of N nutrition on root development and hydraulics. While the effects of elevated [CO 2 ] were again predominantly on hydraulic conductivity, N nutrition acted specifically by constraining deep root penetration into soil. Specifically, 15–40% shallower root systems supported marginally larger shoot canopies. Independent changes to hydraulics and root penetration have implications for survival of fertilized trees under elevated atmospheric [CO 2 ], particularly during water stress.