Early growth and N₂ fixation of arrowleaf clover in response to mineral N, acidity, Mn, and root temperature /
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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: | Seedling vigor of arrowleaf clover (Trifolium vesiculosum Savi.) depends on N availability and may be enhanced by supplementing N₂ fixation with mineral N. In controlled condition experiments, the influence of strain of Rhizobium Leguminosarum biovar trifolii pH root temperature Mn and mineral N on seedling development was evaluated. Addition of starter N (1.8 mg plant⁻¹) to washed sand provided 20% of the total plant N but more than doubled plant growth and N₂ fixation. Soil cores collected from four fields were fertilized with N (31 and 61 kg N ha⁻¹) and planted. Growth of clover on two of the soils was increased approximately 70% by 31 kg N ha⁻¹ without reducing N₂ fixation. For the other two soils, adequate mineral N was already present for supplementing N₂ fixation. Growth decreased approximately 20% for nodulated plants grown in solution culture at pH 4.5 compared to pH 6.5. Shoot weight declined 30% for plants dependent on N₂ fixation or supplemented with mineral N and grown in nutrient solution containing 250 μM Mn (1200 ug Mn g⁻¹ dry plant tissue). When both N sources were available, Mn reduced the percentage contribution of N₂ fixation to total plant N from 60 to 25% indicating N₂ fixation was more sensitive than mineral N uptake to excess Mn. Plants required 8.5 days to nodulate at root temperatures of 18°C and 32°C but only 6.5 days at 25°C. Rhizobial strain did not influence time to nodulate. The quantity of N₂ fixed by either of two rhizobial strains declined by 40% at 18°C compared to 25°C. At 32°C, N₂ fixation declined by 80% for one strain but not for the other strain. Mineral N enhanced seedling growth at all root temperatures. Root temperature did not influence mineral N absorption but did influence the positive affect of mineral N on N₂ fixation. Providing some starter N to supplement N₂ fixation was beneficial to arrowleaf clover seedling development under all growth conditions and depending on the quantity of available mineral N stimulated N₂ fixation. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Agronomy." |
| Physical Description: | xiii, 174 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |