Abstract:
The nitrogen (N) nutrition, crop yield, and respons
es of wheat to arbuscular
mycorrhizal fungi (AMF) were tested in an experimen
tal field under free-air ozone
concentration [O
3
] enrichment (FACE) conditions. The experiment incl
uded three
treatments: ambient [O
3
] (Ambient), elevated [O
3
] (FACE, targeted at ambient [O
3
]×1.5),
and elevated [O
3
] inoculated with an AMF consortium consisting of s
everal
Glomus
species (FACE+AMF). AMF inoculation responsiveness
of wheat was estimated by
comparing plants grown in unsterilized soil inocula
ted with the exogenous AMF and in
untreated soil containing indigenous AMF. Compared
with the Ambient, relatively higher
N contents but lower shoot biomasses of wheat plant
s were observed in the FACE
treatment without AMF inoculation from the tillerin
g stage in February and heading
stage in April, respectively, which significantly (
P< 0.05) decreased grain yield by 28%
at
harvest in June. Under the FACE condition, compared
with the non-inoculated
treatment, AMF inoculation significantly (P< 0.05)
increased root colonization rates both
at the tillering stage and heading stage, and also
significantly (P< 0.05) increased shoot
biomass at the heading stage and, hence, significan
tly (P< 0.05) increased grain yield by
40%
at harvest. However, AMF inoculation significantly
(P< 0.05) decreased total N
content in wheat shoots at the tillering stage, sug
gesting that AMF consortia may enhance
plant tolerance to elevated [O
3
] by elevating root colonization rate rather than p
lant total
N content at early growing stages.
Keywords:
AMF consortia, Crop yield, Free-air ozone concentr
ation enrichment (FACE),
Nitrogen content, Soil urease activity.
