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Hydraulic architecture and water relations of Spartium junceum branches affected by a mycoplasm disease
Author(s) -
Gullo M. A. Lo,
Trifilò P.,
Raimondo F.
Publication year - 2000
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.2000.00614.x
Subject(s) - turgor pressure , xylem , hydraulic conductivity , botany , horticulture , biology , water transport , stomatal conductance , environmental science , water flow , ecology , soil science , photosynthesis , soil water
Plant water relations, xylem anatomy and the hydraulic architecture of 1‐year‐old twigs of Spartium junceum , both healthy and affected by a phytoplasm disease, were studied. The disease causes twigs to be either shortened (witches broom disease, WBD) or flat (fasciate disease, FD). WBD twigs show a sevenfold increase in total leaf area, smaller and shorter xylem conduits, a higher stomatal conductance ( g l ) and a decline of minimum leaf water potentials ( Ψ l ) below the turgor loss point. FD twigs had nearly twice the leaf area of the healthy controls as well as high g l values and Ψ l values below the turgor loss point. Moreover, significant differences between healthy and affected twigs in stem stomatal conductance ( g s ) and in the total stem area were recorded. Affected twigs die back under drought stress, which is explained by a pronounced loss of hydraulic conductivity of the infected stems (40 and 60%) in FD and WBD as well as by the unfavourable ratio of weighted conduit radius ( Σ r 4 ) to total surface area ( A t ), so that the efficiency of the stem in supplying the whole transpiring area with water is strongly reduced.