Controlled Drought Affects Morphology and Anatomy of Salvia splendens

in Journal of the American Society for Horticultural Science
Authors:
Stephanie E. BurnettDepartment of Horticulture, University of Georgia, 1111 Miller Hall Plant Sciences Building, Athens, GA 30602

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Svoboda V. PennisiDepartment of Horticulture, University of Georgia, 1111 Miller Hall Plant Sciences Building, Athens, GA 30602

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Paul A. ThomasDepartment of Horticulture, University of Georgia, 1111 Miller Hall Plant Sciences Building, Athens, GA 30602

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Marc W. van IerselDepartment of Horticulture, University of Georgia, 1111 Miller Hall Plant Sciences Building, Athens, GA 30602

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Polyethylene glycol 8000 (PEG-8000) was applied to a soilless growing medium at the concentrations of 0, 15, 20, 30, 42, or 50 g·L-1 to impose controlled drought. Salvia (Salvia splendens F. Sellow. ex Roem & Shult.) seeds were planted in the growing medium to determine if controlled drought affects morphology and anatomy of salvia. Polyethylene glycol decreased emergence percentage and delayed emergence up to 5 days. Stem elongation of salvia treated with the five lowest concentrations was reduced up to 35% (21 days after seeding), and salvia were a maximum of 53% shorter and the canopy was 20% more narrow compared to nontreated seedlings 70 days after seeding. These morphological changes were attributed to PEG-8000 mediated reduction in leaf water potential (Ψw). The growing medium Ψw ranged from -0.29 to -0.85 MPa in PEG-8000 treated plants, and plant height was positively correlated with Ψw 21 days after seeding. Stem diameter of PEG-treated seedlings was reduced up to 0.4 mm mainly due to reductions in vascular cross-sectional area. Xylem cross-sectional area decreased more than stem and phloem cross-sectional area. Polyethylene glycol 8000 reduced vessel element number, but not diameter.

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