Russian Wheat Aphid (Diuraphis noxia Mord): effect on Argentinean Bread Wheat According to Feeding Periods

Summary

The objective of this study was both to investigate the effects caused by the russian wheat aphid (RWA) from tillering to maturity during tillering and jointing, on the phenology, above dry matter, flag leaf height, relative growth rate and grain yield of an Argentinean wheat variety and evaluate which grain yield components are modified according to aphid feeding period.

Two experiments were conducted during 1995 in La Plata (Buenos Aires province, Argentina). The treatments were: aphids from tillering (AFT), aphids during tillering (ADT), aphids during jointing (ADJ) and control.

Above dry matter was affected according to the moment of RWA presence. A feeding period previous to growth stage 31 and uninterrupted over the complete growing cycle can produce an irreversible grain yield lost with a great incidence on the above dry matter production. Even though ADT had no different performance (p&#003C;0.05) with control in above dry matter at harvest, flag leaf height, relative growth rate, grain number/spike and one thousand grain weight, a recovery in the grain yield had no presented (66.6 % of the control grain yield and only 4.86 % superior to ADJ grain yield). ADJ has the worst performance, so long as it showed lowest above dry matter, relative growth rate and grain yield (through grain weight and grain number/spike). The ability for compensate the RWA damage in feeding periods previous to first node detectable had manifested for above dry matter but not for grain yield. The damage effects reflected both at production rate and components yield modification were in accord with the period when aphids affects the plants.