Identification and characterization of some wheat genotypes resistant to the greenbug Schizaphis graminum (Rond.) (Homoptera: Aphididae)

Tag Elsir E. Abdalla

Abstract


This study was conducted during the last 17 winter seasons 1992-2008; at New Halfa Research Station during 1992-1996 and at the Gezira Research Station from 1997 to 2008, to screen thousands of bread wheat genotypes for desirable morphological defense mechanisms, namely, pubescence, toughness of leaf tissue, accumulated surface wax and leaf curls to the greenbug Schizaphis graminum (Rond.) (Homoptera: Aphididae) as well as for desirable agronomic traits. Batches of genotypes were being received from ICARDA during 1992-1996 and screened in the field from one season to another, using identical methods. Undesirable genotypes were usually discarded and promising ones were resown in subsequent seasons for verification and confirmation. The study was concluded in season 2008 with 15 genotypes characterized with non-preference "antixenosis" type of resistance, manifested through the above mentioned defense mechanisms. Operation of these mechanisms in additive manner had impaired normal feeding, colonizing and sheltering of the greenbug. This was expressed by absence of damage symptoms on genotypes versus Debeira check. The genotypes showed acceptable records of plant height, number of tillers/m², spikes/m², spike length, seeds/head, 1000-seeds weight and grain yield and would be set forth in breeding programs to develop resistant varieties to S. graminum, and to incorporate the controlling gene(s) into improved commercial wheat varieties.


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