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THE CONTRASTING RESPONSE TO SIMULATED ACID RAIN OF LEAVES AND COTYLEDONS OF CABBAGE (BRASSICA OLERACEA L.)
Author(s) -
CAPORN SIMON J. M.,
HUTCHINSON THOMAS C.
Publication year - 1986
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 - 10.1111/j.1469-8137.1986.tb00618.x
Subject(s) - cotyledon , brassica oleracea , seedling , acid rain , brassica , biology , wax , horticulture , botany , epicuticular wax , agronomy , ecology , biochemistry
SUMMARY Brassica oleracea L. (cabbage) was grown in glasshouse and controlled environments and exposed to simulated rains delivered as sprays at pH 5.6‐2.8. A single rain treatment of pH 3.0 given to 10 d old plants elicited a marked downward curvature in the cotyledons, occurring within the duration of the 30‐min spray. Subsequent to this initial response, the cotyledon surface was extensively damaged. In contrast, the older‘true’leaves showed little or no injury after similar treatments. Estimates of the contact angles between rain droplets and leaf surfaces, and SEM studies of adaxial surfaces, indicated that the contrasting morphology of the epicuticular wax on cotyledons and leaves was a major factor determining the extent of acid rain damage. Simulated rain treatments of pH 3.2 and 2.8, starting at the cotyledons stage, reduced plant growth by 17 and 15% respectively over a 20 d period. However, the same treatments given at later stages in development when the‘true’leaves were predominant, had no significant effect on growth. In the natural environment the occurrence of rate, highly acidic rain events during different stages of plant development may be an important determinant of the impact of rainfall on vegetation. The young, seedling stage of species, such as B. oleracea , in which cotyledons show poor development of surface wax, may be particularly vulnerable.