Nutrient solution nitrogen form and barley yellow dwarf virus disease tolerance in oat and wheat

The form of nutrient solution nitrogen (either NH4-N or NO3-N or mixtures o f the two) provided to plants influences the severity of many crop diseases . This greenhouse study was conducted to determine how growth, grain yield, and yield components of oat (Avena sativa L.) and wheat (Triticum aestivum L.) plants given nutrient solutions containing different ratios of NO3-N t o NH4-N would react to barley yellow dwarf virus (BYDV) infection. Fifteen- day-old seedlings (2nd leaf stage) were either infected with BYDV (PAV stra in) or left uninfected. Nutrient solution treatments (started 19 d after ge rmination) provided three ratios of NO3-N to NH4-N (100% NO3, 50:50 NH4:NO3 , or 100% NH4) for a 30-d period, after which plant height and tillers plan t(-1) were measured. Oat and wheat plants given NH4 had fewer tillers than plants given the other nutrient solution treatments. BYDV-infected oat and wheat plants were short than uninfected plants. All pots then received NO3 nutrient solution until plant maturity, after which days to anthesis, prima ry tiller height, grain yield and yield components were measured. In the NH 4 nutrient solution treatments, BYDV infection significantly reduced indivi dual kernel weight in oat and primary tiller height in wheat. These same me asures were not significantly affected by BYDV infection in the NO3 or NH4N O3 nutrient solution treatments. There were no other significant nutrient s olution by BYDV infection interactions for any other dependent variable mea sured. Nutrient solution treatments had no significant effect on grain yiel d, but BYDV infection reduced grain yield by 45% in oat and 46% in wheat. I n conclusion, nutrient solution N form interacted with BYDV infection to al ter disease tolerance in oat (kernel weight) and wheat (primary tiller heig ht), but these alterations had no effect in ameliorating grain yield loss c aused by BYDV disease.