The impact of complete fruit removal on the carbon balance and carbohydrate dynamics of cotton /
Environmental (insect damage, nutrient deficiency, cloudy
| Main Author: | |
|---|---|
| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1994.
|
| Subjects: |
| Summary: | Environmental (insect damage, nutrient deficiency, cloudy weather) and internal (hormonal) factors may limit rates of translocation and thus would be expected to exert an adverse effect on photosynthesis. This research study had two objectives. The first was to determine the impact of fruit removal (loss) on the whole-plant daily carbon balance (daytime carbon exchange rate and nighttime carbon exchange rate). The second objective was to determine the influence of fruit removal on the sugar and starch dynamics and if an accumulation of either affected photosynthesis or respiration. To test the hypothesis that fruit (sink) loss may adversely affect photosynthesis, all fruit was removed from the cotton cultivar 'DPL50' when it reached an hourly average carbon exchange rate (CER) of 105 mg/h. The CER was determined by the use of a whole-plant assimilation chamber. Sugar and starch content was determined by high performance liquid chromatography (HPLC). The daytime CER for the average of all tree replications decreased 5, 8, 10, 10, 9, 10, 9%, at, 1, 2, 3, 4, 5, 6, and 7 d after fruit removal, respectively. The nighttime CER showed a decreased carbon loss of 9, 20, and 9%, at, 1, 2, and 3 d after fruit removal, respectively. Individual plant CERs also showed similar trends found in the daytime and nighttime averages. During this period of decreased photosynthesis there appeared to be no abnormal accumulation of sugar or starch in the source leaves. Starch levels decreased in the top and middle leaf positions, but increased in the lower leaf position. Since little photosynthesis occurred in the lower leaf position it is unlikely that this accumulation of starch caused the observed decrease in photosynthesis. Sugar levels for the top, middle, and lower leaf positions decreased during the dark period and increased during the light period (a normal diurnal trend). These results indicate that the observed decrease in photosynthesis in cotton following fruit removal was not the result of an accumulation of starch or sugar. Therefore, we may conclude that the observed decrease in photosynthesis was likely due to some other mechanism, such as a hormonal, or to the accumulation of other assimilates. |
|---|---|
| Item Description: | Vita. "Major subject: Plant Physiology". |
| Physical Description: | xi, 72 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references. |