Why were proxy traits for CO2 response
more predictive when measured at elevated [CO2]?
For purposes of practical applications of LSSR in plant phenotyping and
selection or breeding for rice CO2 response, it is
sobering that in both our experiments the LSSR measured under elevated
[CO2] was much more predictive than that measured
under ambient [CO2]. (In Exp.1, the latter was not
predictive at all, Fig. 1A.) Given our finding that genotypic LSSR was
highly constitutive between CO2 levels, with a slope of
1 for the linear regression, we can exclude that this difference was
caused by a common adaptive-plasticity response of the LSSR trait for
the population as a whole. However, those genotypes that showed a
reduction in LSSR (or values of alternative proxy traits discussed
further down) under elevated [CO2] tended to have
greater gain in A max and grain yield under
elevated [CO2]. Although this trend was mostly not
significant statistically, it is clear that variable phenotypic
plasticity among the genotypes was responsible for the greater
predictability of e-CO2 response with proxy traits
measured under elevated [CO2].