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Photosynthetic consequences of Marssonina leaf spot differ between two poplar hybrids
Author(s) -
Erickson J. E.,
Stanosz G. R.,
Kruger E. L.
Publication year - 2004
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2003.00968.x
Subject(s) - photosynthesis , biology , hybrid , botany , leaf spot , salicaceae , woody plant
Summary• In foliage of two hybrid poplars, clone DN‐34 ( Populus deltoides × P. nigra ) and clone NM‐6 ( P. nigra × P. maximowiczii ), we examined relationships between photosynthesis and severity of leaf spot induced by Marssonina brunnea f. sp. brunnea , a common disease of many tree species in the Populus genus with the potential to affect growth. • Gas exchange was measured on asymptomatic and diseased foliage in monoculture stands of each clone. The equation Y = (1 – x ) β was used to characterize the relationship between relative photosynthesis ( Y ) and percent leaf spot ( x ), where β represents the ratio between functional impairment and measured lesion area. • Leaf photosynthesis was strongly and negatively correlated with leaf spot severity in both hybrids, and β‐values indicated that photosynthetic impairment extended beyond visibly damaged leaf tissue. However, large differences in β between hybrids indicated differential photosynthetic consequences for a given leaf spot severity. For each hybrid, values of β were positively related to photosynthetic photon flux density incident upon the leaf during gas exchange measurement. • Declines in leaf photosynthesis appeared to result from a disruption of the photosynthetic apparatus by the invading pathogen. However, specific causes for the differential photosynthetic responses of the two hybrids to disease remained elusive.