Effect of irrigation regimes on plant performance and root characteristics of container-grown Photinia X Fraseri /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Plant performance and root characteristics of container-grown Photinia X Fraseri were studied under varying irrigation regimes. Rooted cuttings were transplanted into Metro-mix 500 (W.R. Grace and Co.) for each experiment. Treatments were based on management allowed deficit (MAD) irrigation, which established various levels of water potential and air-filled porosity in the growing medium. In addition, treatments included various levels of evapotranspirational (ET) demand (ie., winter vs. summer, greenhouse vs. field). Plant performance was maximized when water potentials in the growing remained high, but air-filled porosity was maintained between 16% and 23% by volume. Water potential of the medium was a major factor in plant performance under high ET demands; however, under low ET demands, the effect of high water potential was mitigated by a reduction of air-filled porosity in the medium. High water potential nearing that at container capacity, reduced airfilled porosity under these conditions caused a reduction in growth. Increasing irrigation frequency reduced gas exchange of the medium. Lower concentrations of 0₂ and higher C0 ₂ than ambient air were measured in air samples from the growing medium under increased irrigation frequency. Under these reduced aeration conditions, the plants employed lenticel proliferation on the roots as an avoidance mechanism; however, the plants did not employ aerenchyma formation. Plant water status was not significantly reduced until moisture deficit levels exceeded 40%. Transpiration was reduced by approximately one-third in plants where medium moisture was allowed to deplete to 50% of available moisture. Leaf water potential was also decreased significantly. Plants exposed to 75% and 95% moisture deficits showed a more severe reduction in transpiration, increase in stomatal resistance and decrease in leaf water potential. Plant water-use per unit shoot extension (We) decreased as irrigation frequency increased. Increasing irrigation frequency increased evaporation from the growing medium surface. Evaporation from the medium surface accounted for as much as 66% of the total ET of a container-grown plant. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Horticulture." |
| Physical Description: | xiv, 138 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |