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Inhibition of Ferricyanide Reduction in Chloroplasts Prepared from Water‐stressed Cotton Leaves 1
Author(s) -
Fry Kenneth E.
Publication year - 1972
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1972.0011183x001200050045x
Subject(s) - ferricyanide , chloroplast , malvaceae , biology , shoot , osmotic pressure , botany , hill reaction , abutilon , horticulture , photosynthesis , xylem , fiber crop , biochemistry , gene , weed
Water stress was applied to cotton ( Gossypium hirsutum L.) chloroplasts and leaves by the following treatments: (i) prepared chloroplasts were. placed in assay media different osmotic potentials; (ii) cut shoots were allowed to transpire under illumination; (iii) whole potted plants were held for 5 days without irrigation; and (iv) cell sap was expressed from individual leaves via the xylem in a pressure bomb. These treatments caused a decrease in ferricyanide reduction when isolated chloroplasts were assayed potentiometrically for the Hill reaction. The above treatments caused (i) 1.7%, (ii) 1.4%, (iii) 1.8%, and (iv) 1.9% decrease of initial activity rcspectively per bar of water potential decline. This decrease in activity, which was nearly linear with the degree of stress, occurred from —3 to —30 bars leaf water potential in treatments ], 3, and 4, and from —15 to —30 bars in treatment 2. These results indicate that water stress in the leaf can directly influence the photochemical activity of the chloroplasts.