A. Donnelly et al., Does elevated CO2 ameliorate the impact of O-3 on chlorophyll content and photosynthesis in potato (Solanum tuberosum)?, PHYSL PLANT, 111(4), 2001, pp. 501-511
This study examined the impact of season-long exposure to elevated carbon d
ioxide (CO2) and ozone (O-3), individually and in combination, on leaf chlo
rophyll content and gas exchange characteristics in potato (Solanum tuberos
um L. cv. Bintje), Plants grown in open-top chambers were exposed to three
CO, (ambient, 550 and 680 mu mol mol(-1)) and two O-3 treatments (ambient a
nd elevated; 25 and 65 nmol mol(-1), 8 h day(-1) means, respectively) betwe
en crop emergence and maturity; plants were also grown in unchambered field
plots. Non-destructive measurements of chlorophyll content and visible fol
iar injury were made for all treatments at 2-week intervals between 43 and
95 days after emergence, Gas exchange measurements were made for all except
the intermediate 550 mu mol mol(-1) CO2 treatment. Season-long exposure to
elevated O-3 under ambient CO2 reduced chlorophyll content and induced ext
ensive visible foliar damage, but had little effect on net assimilation rat
e or stomatal conductance. Elevated CO2 had no significant effect on chloro
phyll content, but greatly reduced the damaging impact of O-3 on chlorophyl
l content and visible foliar damage. Light-saturated assimilation rates for
leaves grown under elevated CO2 were consistently lower when measured unde
r either elevated or ambient CO2 than in equivalent leaves grown under ambi
ent CO2. Analysis of CO2 response curves revealed that CO2-saturated assimi
lation rate, maximum rates of carboxylation and electron transport and resp
iration decreased with time. CO2-saturated assimilation rate was reduced by
elevated O-3 during the early stages of the season, while respiration was
significantly greater under elevated CO2 as the crop approached maturity. T
he physiological origins of these responses and their implications for the
performance of potato in a changing climate are discussed.