Response of photosynthesis and chlorophyll fluorescence to acute ozone stress in tomato (Solanum lycopersicum Mill.)

Abstract

The crop sensitivity to ozone (O 3 ) is affected by the timing of the O 3 exposure, by the O 3 concentration, and by the crop age. To determine the physiological response to the acute ozone stress, tomato plants were exposed to O 3 at two growth stages. In Experiment I (Exp. I), O 3 (500 µg m -3 ) was applied to 30-d-old plants (PL30). In Experiment II (Exp. II), three O 3 concentrations (200, 350, and 500 µg m -3 ) were applied to 51-d-old plants (PL51). The time of the treatment was 4 h (7:30 -11:30 h). Photosynthesis and chlorophyll fluorescence measurements were done 4 times (before the exposure; 20 min, 20 h, and 2-3 weeks after the end of the treatment) using a LI-COR 6400 photosynthesis meter. The stomatal pore area and stomatal conductance were reduced as the O 3 concentration increased. Ozone induced the decrease in the photosynthetic parameters of tomato regardless of the plant age. Both the photosystem (PS) II operating efficiency and the maximum quantum efficiency of PSII photochemistry declined under the ozone stress suggesting that the PSII activity was inhibited by O 3 . The impaired PSII contributed to the reduced photosynthetic rate. The greater decline of photosynthetic parameters was found in the PL30 compared with the PL51. It proved the age-dependent ozone sensitivity of tomato, where the younger plants were more vulnerable. Ozone caused the degradation of photosynthetic apparatus, which affected the photosynthesis of tomato plants depending on the growth stage and the O 3 concentration.

Effects of acute ozone stress on reproductive traits of tomato, fruit yield and fruit composition

“…First, the fruit setting was altered, leading to a decrease in the fruit number per truss. Moreover, a temporary decrease in photosynthesis is observed at the plant scale in response to ozone stress . Therefore the source/sink ratio had been possibly impacted by ozone in the present experiment.…”

“…Ozone has been shown to trigger foliar leaf injury, reduced photosynthetic rate and impaired photosynthetic systems . Reduced root growth and extension rate were also reported by Thwe et al ., as a consequence of leaf injury and dysfunction of photosynthetic systems under ozone stress . Hence these impacts could lead to decreased availability of energy and resource (carbohydrates and water), which may become limiting for fruit setting and to sustain organ growth, thus triggering a decrease in the number of well‐developed fruits.…”

Exogenous GSH protects tomatoes against salt stress by modulating photosystem II efficiency, absorbed light allocation and H2O2-scavenging system in chloroplasts

“…The quantum efficiency of PSII and the extent of photoinhibition are continually used to ensure the energy distribution state in the thylakoid membrane (Hu et al 2014;Zhang et al 2015). The most vital chlorophyll fluorescence parameters are F v /F m , ETR, NPQ, q P , and 1-q P values, and they are broadly applied to plant stress physiology studies (Baker and Rosenqvist 2004;Olvera-González et al 2013;Thwe et al 2014). Excess energy may cause photoinhibition and even severe damage to the photosynthetic apparatus (Sanda et al 2011;Wilhelm and Selmar 2011;Wu and Bao 2011).…”

Root Zone Cooling and Exogenous Spermidine Root-Pretreatment Promoting Lactuca sativa L. Growth and Photosynthesis in the High-temperature Season

“…The quantum yield of PSII electron transport [PhiPSII = (F′ m - F s )/F′ m ], the efficiency of excitation energy capture by open PSII reaction centers [ F′ v /F′ m = (F′ m - F′ o )/F′ m ], photochemical quenching [ qP = (F′ m - F s )/(F′ m - F′ o ) ], and non-photochemical quenching [qN = (F m - F′ m )/(F m - F′ o )] were calculated from the measured parameters ( Maxwell and Johnson, 2000 ). The quantum yield of the carboxylation rate (PhiCO 2 ) was calculated as: PhiCO 2 = ( P N – P Ndark )/(I × αleaf; Thwe et al, 2014 ), where P N is the assimilation rate, P N dark is the dark assimilation rate (μmol m -2 s -1 ), and α is the initial slope of the light curve at low PPFD.…”