Studies on the plant growth regulating effect of chlordimeform in cotton /
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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: | The cotton (Gossypium hirsutum. L.) pesticide chlordimeform (CDF) [N'- (4-chloro-0-tolyl)-N-N-dimethylformamidine] has increased lint yield in research trials more than is expected from its pesticidal properties. The objectives of this research were to investigate plant physiological effects of CDF and how the yield response of cotton to early season CDF application is modified by irrigation, N fertility, and plant density. Chlordimeform exhibited cytokinin-like activity in excised radish (Raphanus sativa) cotyledons, providing a possible explanation for cotton yield enhancement. However, no hormone activity was found in cytokinin-starved soybean (Glycine max) callus. Attempts to describe the physiological mechanism for cotyledon expansion with CDF treatment were unsuccessful. In one glasshouse and one of two controlled environment chamber studies, increased photosynthetic rates were found on uppermost fully expanded leaves treated with CDF. The increase found in the glasshouse study coincided with greater plant vegetative and reproductive growth. No differences in growth were found in either chamber study. Leaf photosynthesis was higher in field grown CDF-treated plants (0.14 kg a.i. ha^-1 applied six times) in early July 1986 and early June 1987, averaged over two irrigation (dryland and furrow irrigated) and four N levels (0, 40, 80, and 120 kg ha^-1). As water stress developed in late July 1986, the CDF-treated dryland plants had higher leaf gas exchange than untreated dryland plants at the upper N rates. The higher photosynthetic rates with CDF treatment under dryland conditions at that time were associated with more and heavier bolls on the upper nodes at the end of the season. Chlordimeform treatment increased lint yield by about 200 kg ha^-1 under irrigated conditions in 1986. Among the CDF-untreated plants in 1987, irrigation increased yield at the upper three N rates. No difference in yield between irrigation levels occurred among the CDF-treated plants at any N level. No yield increase occurred in a related study investigating the effect of plant density (4, 8, and 16 plants m^-2) on CDF yield enhancement. More bolls were on the first sympodial fruiting position of the middle fruiting nodes with CDF treatment under irrigated conditions and in the plant density study both years. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Agronomy." |
| Physical Description: | xi, 89 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 84-88). |