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SOME EFFECTS OF THREE HERBICIDAL AUXINS ON STOMATAL MOVEMENTS
Author(s) -
PEMADASA M. A.,
JEYASEELAN K.
Publication year - 1976
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.1469-8137.1976.tb04648.x
Subject(s) - guard cell , mcpa , chemistry , potassium , carbon dioxide , starch , 2,4 dichlorophenoxyacetic acid , fusicoccin , botany , biophysics , horticulture , biochemistry , agronomy , biology , organic chemistry , pesticide , atpase , enzyme
S ummary The effects of 2 , 4‐dichlorophenoxyacetic acid (2,4‐D), 2, 4,5‐trichlorophenoxyacetic acid (2,4,5‐T) and 2‐methyl‐4‐chlorophenoxyacetic acid (MCPA) on stomatal opening on illumination of excised, turgid leaves of Stachytarpheta indica were studied by microscopic examination of epidermal strips fixed in absolute ethanol. All three herbicides prevented wide opening of stomata and accumulation of potassium in the guard cells; hydrolysis of stomatal starch was hindered by 2, 4,5‐T and MCPA and hastened by 2, 4‐D. Carbon dioxide‐free air was effective in compensating substantially the effects of 2, 4,5‐T and MCPA but not of 2, 4‐D. It is concluded that 2, 4,5‐T and MCPA arrest light‐induced stomatal opening partly by disturbing the carbon dioxide balance in the leaf and partly by hindering starch hydrolysis and potassium accumulation in the guard cells, whereas 2, 4‐D appears to exert a more direct effect, probably by affecting the membrane permeability, on guard cells although inhibition of potassium accumulation may also be partly involved in its action.