Winter wheat responses to bird cherry-oat aphids and barley yellow dwarf virus infection

Grain yield loss caused by bird cherry-oat aphid (Rhopalosiphum padi L,) in festation and barley yellow dwarf virus (BYDV) infection mag result from di rect damage to the winter wheat( Triticum aestivum L,) crop as well as from reduced crop tolerance to stress environments, This greenhouse study measu red the effects of R. padi infestation, BYDV infection, or a combination of R. padi plus BYDV on plant height, date of anthesis, yield, and yield comp onents of four winter wheat varieties ('Roughrider', 'Norstar', 'TAM 107', and 'Vona') in the absence of additional environmental stresses. Treatments Here applied at the two-leaf growth stage. Early in the pre-vernalization growth period, R. padi treatment (alone or in combination with BYDV) reduce d plant height to about 55 to 60% of the control plant height while BYDV tr eated plants were about 90% of control. During the post-vernalization growt h period, plant heights attained about 90% of control in the R. padi treatm ent, to about 80% of control in the BYDV treatment and to about 70% of cont rol in the R, padi + BYDV treatment. Dates of anthesis Here later in the R, padi + BYDV treatments than in the R. padi treatments for Norstar, Roughri der, and Vona but not for TAM 107, Individual kernel Heights in the BYDV an d R. padi + BYDV treatments were less than control or R, padi treatments fo r Norstar, TAM 107, and Vona but not for Roughrider. Control or R. padi-tre ated plants had a greater number of fertile heads than plants given the BYD V or R. padi + BYDV treatments. Grain yield was strongly associated with ke rnel number per plant, The number of kernels per plant was reduced 19% by t he R. padi treatment, 36% by the BYDV treatment, and 50% by the R. padi + B YDV treatment. Grain yield was reduced 21% by the R. padi treatment, 46% by the BYDV treatment, and 58% by the R. padi + BYDV treatment. With the exce ption of date of anthesis and individual kernel weight, there Here no signi ficant treatment by variety interactions for plant height, grain yield, and yield components. We conclude that R, padi infestation and BYDV infection caused significant yield reductions and that the varieties tested had littl e difference in their responses to these treatments in the absence of addit ional environmental stress.