%0 Article
%T A method for measurement of actue leaf injury on tobacco indicator plants.
%A Mortensen, Lisbeth
%A Weisberg, Knud V.
%D 1981
%J Silva Fennica
%V 15
%N 4
%R doi:10.14214/sf.a15368
%U https://silvafennica.fi/article/5141
%X <p>A technique for instrumental scoring of damaged leaves on tobacco (<em>Nicotiana tabacum</em>) indicator plants caused by ozone in the lower atmosphere is being developed. The leaves are photographed <em>in situ</em> with an integrated unit, which illuminates the leaf from behind and keeps the camera in a well-defined position. By using microfilm and a minus green filter, it is possible to obtain negatives where the necrotic flecks appear as dark spots on a white leaf. The negatives are scanned in a TV-system and the size of the damaged fraction of the leaf is calculated by a microprosessor and is shown as a percentage of the leaf.</p>