Effects of Ozone on Leaf Senescence, Photochemical Efficiency and Grain Yield in Two Winter Wheat Cultivars

Abstract

The adverse effects of tropospheric ozone (O 3 ) on crop photosynthesis, growth and yield have been documented in numerous studies over the last decades, but little information from field experimentation exists on how modern European winter wheat cultivars respond to O 3 . Two winter wheat cultivars (Astron and Pegassos) differing in development characteristics were exposed to non-filtered ambient air or non-filtered air plus 30 ppb and non-filtered air plus 60 ppb O 3 (8 h day À1 ) in open-top field chambers. At several dates during growth, green leaf area was determined by destructive harvests. Leaf gas exchange, pigment content and xanthophyll cycle activity, and photochemical efficiency by chlorophyll a fluorescence were measured. O 3 exposure induced accelerated senescence with no difference between cultivars. Photosynthesis declined especially in Pegassos; however, stomatal conductance was hardly affected by O 3 . Pigment contents were reduced by O 3 exposure, and de-epoxidation index increased. Photochemical efficiency (F v /F m ) declined, whereas actual quantum yield (Φ PSII ) did not respond to O 3 . O 3 exposure reduced grain yield in both cultivars. However, yield of Pegassos was more affected by O 3 exposure than yield of Astron, suggesting a higher O 3 sensitivity of Pegassos. The data presented in this manuscript indicate a need to test whether high-yield varieties such as Pegassos are particularly sensitive to O 3 exposure.

Differential root responses in two cultivars of winter wheat (Triticum aestivum L.) to elevated ozone concentration under fully open‐air field conditions

“…wheat, rice, etc.) have been noted since the 1990s, which may get worse in the future (Avnery, Mauzerall, Liu, & Horowitz, ; Burkart et al., ; Clausen et al., ; Feng & Kobayashi, ).…”

Radish (Raphanus sativus L.) Cultivar‐Specific Response to O3: Patterns of Biochemical and Plant Growth Characteristics

“…A was reduced due to exposure to 80 nL L −1 O 3 at all sampling dates, with B plants showing more reduction than other cultivars. The increased g s in response to O 3 in B and CB plants would allow higher O 3 influx and consequently more reduction in A , leading to sever reduction in carboxylation efficiency and PSII photochemistry . The response of g s does not depend on leaf position or the development of visible injury but may depend on internal physiological and metabolic processes that are genetically controlled …”

The impact of elevated ozone on the ornamental features of two flowering plants (Tagetes erecta Linn. and Petunia hybrida Vilm.)

“…In the present study, although the changes in carotenoid levels under O 3 stress varied with plant growth stage and plant species, we detected a reduced chlorophyll-to-carotenoid ratio, indicating a preferential degradation of chlorophyll over carotenoids. This effect may be one of the main reasons for leaf yellowing caused by O 3 stress, as revealed in the studies of Biswal (1995) and Burkart et al (2013) on the yellowing of senescent leaves.…”