Tropospheric ozone is a worldwide phenomenon causing injuries to forest trees. Californian ponderosa and Jeffrey pines are well known for their sensitivity to ozone, while other pine species have varied in their susce...Tropospheric ozone is a worldwide phenomenon causing injuries to forest trees. Californian ponderosa and Jeffrey pines are well known for their sensitivity to ozone, while other pine species have varied in their susceptibility. Sensitive pine species are known for their chlorotic mottle and tip burn symptoms, caused by ozone air pollution. Epistomatal wax plugs and filamentous waxes around stomata are typical for pine needle surfaces. In this study, we investigated epistomatal and epicuticular needle waxes in eight species of field-grown pines in 1985, 1986 and 2006. The epistomatal wax plugs were present in asymptomatic needles without chlorotic mottle (23% of needles). A lack of wax plugs in needles with chlorotic mottle and tip burn symptoms was common (76% of needles). More abundant existence of mottling associated with stomata without wax plugs in two-year-old needles, compared with one-year-old needles (43% and 33%, respectively), indicated chronic injury development over time.展开更多
文摘Tropospheric ozone is a worldwide phenomenon causing injuries to forest trees. Californian ponderosa and Jeffrey pines are well known for their sensitivity to ozone, while other pine species have varied in their susceptibility. Sensitive pine species are known for their chlorotic mottle and tip burn symptoms, caused by ozone air pollution. Epistomatal wax plugs and filamentous waxes around stomata are typical for pine needle surfaces. In this study, we investigated epistomatal and epicuticular needle waxes in eight species of field-grown pines in 1985, 1986 and 2006. The epistomatal wax plugs were present in asymptomatic needles without chlorotic mottle (23% of needles). A lack of wax plugs in needles with chlorotic mottle and tip burn symptoms was common (76% of needles). More abundant existence of mottling associated with stomata without wax plugs in two-year-old needles, compared with one-year-old needles (43% and 33%, respectively), indicated chronic injury development over time.
