Funding
This work was supported by the National Natural Science Foundation of
China (Grant No. 41530533).
Abatract
The response of crop photosystem activity to a certain level of
[CO2] elevation have been widely concerned. However,
long-term effects of elevated [CO2] over
multi-generations of crops received little attention. Using open-top
chambers, we set up two treatments of elevated [CO2]
from 2016 to 2019 in rice (Oryza sativa ) growing seasons.
One treatment was stepwise increase
(SI) of +40 µmol mol-1 per season, the other was
constant increase (CI) of +200 µmol mol-1. Rice seeds
harvested in each [CO2] environment was planted
successively. Seeds from ambient [CO2] were also
planted in SI and CI OTCs in next year to study the short-term effect.
We measured the diurnal change in PSII functionality of leaf in 2019.
Results showed that both SI and CI promoted PSII function. SI was more
beneficial to improve efficiency of
electron trapping
and transporting in PSII and
performance index of leaf. The maximal
photochemical
efficiency of PSII decreased linearly with increasing photosynthetic
photon flux density throughout the day. Predawn efficiency decreased
dramatically with the development of growth stages. Together, we found
PSII efficiency benefit from multi-year [CO2]
elevation, which could help to
better understand the response of
electron transport to elevated [CO2].
Keywords
multi-year [CO2] elevation, PSII efficiency, rice,
Fv/Fm, diurnal change, stepwise
increase, constant increase, short-term