الفهرس 
INTRODUCTION
Aphid effectsOnly 14 pages are availabe for public view
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Abstract
The present investigation was carried out at the Experimental Farm Df the Faculty of Agrieulture, Assiut University, during the three successive winter seasons of 1989/90, 1990/91 and 1991/92.
The objective were to evaluate bread wheat germplasm for aphid preference and tolerance, morphological traits, yield and its components and to study correlation and path coefficient analysis of yield and its components.
The wheat germplasm consists of 156 genotypes, Triticum aestivuin
L. Some of these genotypes were introduced from USA, Canada, Rodisia, Hungary and Saudi Arabia, while most of them are local and collected from fields of several locations of Egypt. Six local cultivars, i.e., Giza 15, Giza 158, Gza 160, Sakha 8, Sakha 80 and Sakha 69 were used as checks.
Each year, two separate experiments were conducted. The first experiment (Exp. I) was kept free from aphid infestation by chemical control (sprayed three times). The second one (Exp. 2) was left to natural aphid infestation without any chemical control. A randomized complete block design of four replications was used for each experiment in the three seasons of experimentation. In the first and the second seasons the genotypes were divided into sets of 18 and 19 genotypes each, respectively. The sets were randomly distributed within each replicate.
The studied characters included, (1) aphid preference or non- preference and tolerance, (2) morphological traits, i.e. days to heading.