Foster, D.G. and Teetes, G.L. and Johnson, J.W. and Ward, C.R. (1977) Resistance in sorghums to the Banks grass mite. Journal of Economic Entomology, 70 (2). pp. 259-262.
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Abstract
Studies were carried out in Texas on the resistance mechanisms of sorghum lines to Oligonychus pratensis (Banks.). As judged by mite mortality on leaf disks after 24, 48 and 72 h, there was no difference in the non-preference response on SC 599-6 (a line previously identified as mite-resistant), Tx 7000 (a common parental grain-type line susceptible to the mite), KS 30 (a non-grain type line) resistant to Schizaphis graminum (Rond.) and Honey (a sweet line high in sugar and a common forage sorghum). However, the mean number of mites on each line at various growth stages indicated that mite numbers were generally higher at growth stages 2-6 than at stages 1, 7 and 8.Life-spans did not differ significantly on SC 599-6, SC56-6 (a line previously considered mite-resistant), Tx 7000, B Tx 378 (a maintainer line susceptible to the mite), KS 30, Sweet Sudan (a sweet grassy line) and Honey. Mites reared on intact leaves at growth stages 1-6 had a longer life-span (averaging 25.7 days) and oviposition period (11.6 days) than did mites reared on leaf disks at growth stages 6-8 (the number of days for the latter mites being 19.1 and 8.9, respectively). However, fewer eggs were laid daily by females on plants at growth stages 1-6 than were by those on plants at stages 6-8 (the numbers being 4.3 and 11.1, respectively). Tolerance appeared to be a major resistance mechanism of SC 599-6 as the data indicated that less damage occurred on that line even when infested with mite populations equal to those on Tx 7000 or Honey.ADDITIONAL ABSTRACT:Oligonychus pratensis individuals showed no particular preference when given the choice of a field-resistant strain (SC599-6), a susceptible grain sorghum (TX7000), a grassy sorghum (KS30) and a sweet sorghum (Honey). No significant differences were found in the life spans of mites reared on any of these lines or on SC56-6 (considered to be resistant), except that the protonymph stage on SC559-6 tended to be shorter than on Honey. Total fecundity was highest on leaf discs of TX7000 and SC599-6; it was least on Honey. The egg incubation period tended to be shortest on SC599-6 and TX7000, followed by Honey. The larval development stage was longest on SC599-6 and shortest on Honey. In tolerance studies in which mite numbers on infested plants were subsequently compared with the resulting damage, Honey was most severely damaged and KS30 and SC599-6 least. It is concluded that tolerance is the major resistance mechanism in SC599-6
| Item Type: | Article |
|---|---|
| Author Affiliation: | Department of Entomology, Texas A&M University, College Station, TX 77843, USA |
| Subjects: | Crop Improvement |
| Divisions: | Sorghum |
| Depositing User: | Ms K Syamalamba |
| Date Deposited: | 20 Mar 2012 06:40 |
| Last Modified: | 20 Mar 2012 06:40 |
| URI: | http://eprints.icrisat.ac.in/id/eprint/4006 |
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