ABSTRACT
Cotton plants subjected to a series of water deficits exhibited stress
adaptation In the form of osmoregulation when plants were subjected to a
subsequent drying cycle. After adaptation, the leaf water potential coinciding
with zero turgor was considerably lower than in plants that had never
experienced a water stress. The relationship between leaf turgor and leaf
water potential depnded O leaf age.
Nonstomatal factors severely limited photosynthesis in adapted plants
at high leaf water potential. Nonetheless, adapted plants maintained photosyPnthesis
to a much lower leaf water potential than did control plants, in
part because of increased stomatal conductance at low leaf water potentials.
Furthermore, adapted plants continued to translocate recently derived
photosynthate to lower leaf water potentials, compared with control plants.
Stress preconditioning modffied cellular ultrastructure. Chloroplasts of
fully turgid adapted leaves contained extremely large starch granules,
seemed swollen, and had some breakdown of thylakoid membrane structure.
In addition, cells of adapted leaves appeared to have smaller vacuoles
and greater nonosmotic cell volume than did control plants.
ABSTRACTCotton plants subjected to a series of water deficits exhibited stressadaptation In the form of osmoregulation when plants were subjected to asubsequent drying cycle. After adaptation, the leaf water potential coincidingwith zero turgor was considerably lower than in plants that had neverexperienced a water stress. The relationship between leaf turgor and leafwater potential depnded O leaf age.Nonstomatal factors severely limited photosynthesis in adapted plantsat high leaf water potential. Nonetheless, adapted plants maintained photosyPnthesisto a much lower leaf water potential than did control plants, inpart because of increased stomatal conductance at low leaf water potentials.Furthermore, adapted plants continued to translocate recently derivedphotosynthate to lower leaf water potentials, compared with control plants.Stress preconditioning modffied cellular ultrastructure. Chloroplasts offully turgid adapted leaves contained extremely large starch granules,seemed swollen, and had some breakdown of thylakoid membrane structure.In addition, cells of adapted leaves appeared to have smaller vacuolesand greater nonosmotic cell volume than did control plants.
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