Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/26/2007
Publication Date: 8/17/2007
Citation: Riedell, W.E., Osborne, S.L., Jaradat, A.A. 2007. Crop mineral nutrient and yield responses to aphids or barley yellow dwarf virus in spring wheat and oat. Crop Science. 47:1553-1560. Interpretive Summary: Because root systems provide shoot organs with essential mineral nutrients, potential reductions in root system function of aphid-infested or BYDV-infected plants may play an important role in grain yield reductions. We felt that a field study of cereal aphid and aphid-borne disease effects on cereal crop mineral nutrition would provide information on how root function and shoot mineral concentrations are affected when plants are damaged by these stress-causing biological organisms. This knowledge may suggest new soil fertilizer management practices that ameliorate this loss of root system function and reduction in yield. The objectives of this 2-yr field study were to determine how plant stress caused by 3 different aphid species or an aphid-vectored viral disease affected leaf mineral nutrients, chlorophyll, and agronomic traits (leaf area, canopy temperature, yield, and yield components). There were relatively strong responses of dependent variables to year as well as to year x crop, and year x treatment interactions. Differences in weather conditions across the two years of the study (greater drought stress in 1997 than 1998) likely were the cause of these year effects and interactions. In addition, significant crop x treatment interactions for agronomic variables (grain yield, seeds m-1 and TKWT) likely were present because RWA tolerance is much greater in oats than in wheat. Even with these potential interactive responses to drought stress and RWA tolerance, statistical analyses identified N, K, and Mg as potentially important elements in cereal plant responses to stress caused by aphid feeding damage or aphid-vectored disease. The data presented in this study suggest that small grain producers should undertake soil and crop management strategies that guard against crop deficiencies in these three essential plant nutrients. However, additional applications of these elements to the soil likely would not ameliorate the stress and yield loss caused by aphids or aphid-transmitted disease in cereal grains.
Technical Abstract: There is little information available that describes how changes in root system biomass caused by aphid feeding or aphid-transmitted viral disease affect root system function in spring wheat (Triticum aestivum L.) or oat (Avena sativa L.). This 2-yr field experiment was conducted to determine how leaf mineral nutrients (N, P, K, Ca, Mg, Zn, Fe, Mn, and Cu), chlorophyll (chl), and agronomic traits (LAI, leaf area, canopy temperature, yield, and yield components) responded to crop stress imposed at the 3-leaf development stage by aphid feeding [greenbugs (GB), Schizaphis graminum Rondani; Russian wheat aphids (RWA), Diuraphis noxia Mordvilko; bird cherry-oat aphids (BCOA), Rhopalosiphum padi L.] or by an aphid-vectored virus (barley yellow dwarf virus; BYDV). Leaf chl, N, Ca, and Mg concentrations (measured at the boot development stage) were about 25% less in BYDV-infected than control treatments. Grain yield deviation from control (dY; control treatment grain yield subtracted from grain yield for each crop-treatment combination) was most negative for BYDV treatment (-2164.5 kg/ha) and least negative for GB treatment (-745.5 kg/ha); with RWA (-900.6 kg/ha) and BCO (-789 kg/ha) treatments having intermediate effects. Mineral nutrients and chl (N, K, Mg, Mn, and chl) were significantly correlated (Canonical r=0.94, p<0.000) with agronomic traits (LAI, canopy temperature deviation from control, leaf area, and grain yield), and explained 62.1% of the variation in agronomic traits. We conclude that N, K, and Mg are potentially important elements in cereal crop responses to stress caused by aphid feeding damage or aphid-vectored disease.