Physiological responses of loblolly pine (Pinus taeda L.) to silicon and water stress /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1988.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Silicon (Si) and/or water stress were used as means to study growth, elastic, and osmotic properties of loblolly pine. The objectives of this study were to localize Si in needle and to determine its effects on seedling growth and water relations in water stress conditions. Seedlings were grown from seed in a greenhouse in either sand or fritted clay media. Silicon in the form of K2SiO3 was added to the fertilizer solution at concentrations of 20, 60, and/or 100 mg/l, either once or twice a week. Water stress was induced in the seedlings, by withholding water, after several weeks of Si treatment Electron microscopy and x-ray analysis revealed that Si deposited exclusively in the epidermis of Si-treated needles. Analysis with atomic absorption revealed that Silicon-treated needles accumulated about three times more Si than did controls. Silicon increased both turgid-fresh and dry weights of loblolly pine tissues from 6% to 36%. Growth enhancement was more pronounced under water stress conditions. Generally, for the seedlings grown in sand media, diffusive resistance (r[w]) was increased and transpiration (T) was decreased for all concentrations and frequencies of Si application. Both r[w] and T responses were along a concentration gradient, but in opposite direction and were most pronounced when the seedlings were conditioned with water stress. However, for the seedlings grown in fritted clay media, Si reduced r[w] and increased T during an 11-day stress cycle. Regardless of such contrasts in responses, all Si-treated seedlings consistently maintained higher water potential (ψ[w]) throughout the stress cycles. Silicon treatment made the shoots more elastic, while water stress made them less elastic; and Si raised the osmotic potential (ψ[s]) of the shoots, while water stress reduced them. This study strongly suggests that Si is a beneficial element, especially in water stress conditions. Silicon-induced increase in ψ[w], r[w], and elasticity will presumably help the seedlings to maintain turgor, and hence, improve survival and continue growth as the soil ψ[w] declines. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Forestry." |
| Physical Description: | xiv, 127 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 117-126). |