Effect of temperature/photoperiod on sorghum resistance mechanisms to biotype C and E greenbugs (Homoptera: Aphididae), and biotype differentiation by DNA content /
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| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1991.
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| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | The effect of temperature and photoperiod on tolerance, antixenosis, and antibiosis of sorghum lines resistant to biotype C (Tx2737 and Tx2783) and biotype E (Tx2783) greenbugs at 21, 26, and 30°C, and 10L:14D and 14L:10D was determined using the sorghum line Tx430 as a susceptible check. Damage to resistant sorghum lines was less than to the susceptible check (usually about 1/2 as much). Tolerance resistance was at least twice as great on the resistant sorghums at 30°C than at 21 or 26°C. The level of antixenosis resistance was less than that of tolerance resistance. At 21 and 26°C, the resistant sorghum lines were as preferred as the susceptible sorghum line. Antixenosis resistance was greatest at 30°C. Greenbug development and reproduction was affected by temperature and resistant sorghum lines. Days from birth to maturity was greatest at 21°C, but was equally as long at 30°C on the resistant sorghums. Progeny production was severely reduced by the resistant sorghum lines, especially at 30°C. At 30°C, greenbugs reproduced three times fewer progeny on the resistant sorghums than on the susceptible sorghum. Greenbug longevity was shorter at 30°C than at 21 and 26°C, but resistant sorghums had a greater effect, further reducing longevity. Photoperiod did not appear to affect the level of the three resistance mechanisms. These data confirm the importance of temperature in assessing resistance mechanisms and support the contention that temperature should be a consideration in all resistance assessment research. Difference in cellular DNA content between biotype C and E greenbugs was not great; however, for all experiments, biotype E greenbugs cellular DNA content averaged about 1.05 pg/cell while that of biotype C greenbugs was 1.02 pg/cell. The significance of this difference is unknown. Greenbugs reared on sorghum had lower amounts of DNA (0.99, 1.03, and 1.07 pg/cell) for biotype C, biotype E, and field collected biotype E, respectively, compared to the same biotypes of the greenbug on wheat and johnsongrass. The range of DNA content in greenbugs was 0.91-1.24 pg/cell, and the mean over all experiments was 1.06 pg/cell. These results suggest that the use of flow cytometric DNA analysis should be further tested as a possible means of rapid greenbug biotype identification. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Entomology." |
| Physical Description: | xv, 106 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |