Piñero, M.C., Pérez-Jiménez, M.,
López-Marín, J., Varóó, P. and del Amor, F.M.
2018
"Differential effect of the nitrogen form
on the leaf gas exchange, amino acid
composition, and antioxidant response
of sweet pepper at elevated CO2"
Plant Growth Regulation 86: 37-48
SUMMARY:
Piñero et al. say
"the data acquired
in this study will be useful to achieve
better N-fertilizer management
for this important crop,
especially under climate change."
Elevated CO2 benefited plant growth,
increasing shoot dry weights
from 6% to 33% among the different
N form treatment ratios, while also
improving water use efficiency
and chlorophyll fluorescence.
Elevated CO2 was able to totally
compensate for the dry weight declines
experienced by ammonium toxicity.
Sweet red peppers happen
to be my favorite fruit --
people think they're vegetables
-- I spend about $5 a week on them !
Ye Editor
Sweet red peppers happen
to be my favorite fruit --
people think they're vegetables
-- I spend about $5 a week on them !
Ye Editor
DETAILS:
Piñero et al. (2018) say the use of NH4+
(ammonium) is "a good alternative to
nitrate-based fertilizer" in agriculture."
But when applied as the sole source of N fertilizer,
NH4+ can be toxic and reduce plant growth
and yield.
So some combination of NO3- and NH4+
fertilization is often used to prevent ammonium
toxicity and improve crop yields.
Ammonium (NH4+) is a source of nitrogen (N)
whose oxidation state "does not need
to be reduced in plant cells."
"NH4+ is an intermediate in many
metabolic reactions and fundamental
processes of plants, such as NO3- reduction,
photorespiration, degradation of amides,
and catabolism of proteins."
Little is known about
the interactive effects of
different N forms under elevated
atmospheric CO2 conditions.
Piñero et al. "investigate(d) the extent
to which the optimal form of the N-supply
can increase growth at an elevated
CO2 concentration."
The team of five Spanish researchers
grew sweet pepper (Capsicum annuum,
cv. Melchor) plants under ambient
or elevated CO2 concentrations
with nutrient solutions of different
NO3- / NH4+ ratios.
Under ambient CO2 conditions,
ammonium toxicity decreased
plant growth relative to control
conditions (100% N from NO3-).
All of the dry weights
in the elevated CO2 treatments
were significantly higher
for each N form ratio and none
were significantly lower than
the plant dry weight experienced
under control conditions of
100% N from NO3-.
The best treatment regime
to optimize plant growth
was a low dose of NH4+ fertilizer
(10% NH4+ and 90% NO3-)
under elevated CO2 (800 ppm)
conditions.
