Nitrogen Fixation, Ureide, and Nitrate Accumulation Responses to Soybean Aphid Injury in Glycine max

ABSTRACT

There is little information available about soybean aphid (Aphis glycines Matsumura) effects on the physiology and mineral nutrition of soybean (Glycine max [L.] merr.). Controlled-environment studies were conducted to measure soybean aphid infestation effects on dry weight, nitrogen (N) fixation, ureide-N, and nitrate-N concentration and accumulation. Plants grown in perlite using –N nutrient solution culture were infested at the 3rd trifoliolate (V3) stage and measured for N fixation, nodule characteristics, and ureide-N concentration at the full pod (R4) stage. When compared to uninfested control plants, aphid infestation reduced total nodule volume per plant by 34%, nodule leghemoglobin per plant by 31%, plant N fixation rate by 80% and shoot ureide-N concentration by 20%. Soil-grown plants were infested at the first trifoliolate (V1) stage and shoots were measured for dry weight, nitrate-N, and ureide-N at the full bloom (R2) stage. Infestation reduced shoot dry weight by 63%, increased nitrate-N concentration by 75%, but did not significantly affect ureide-N concentration. Because nutrient concentration is a single-point measurement that results from the integration of two dynamic processes, nutrient accumulation and dry matter production, we conclude that aphid-induced reductions in N fixation, coupled with decreased dry weight accumulation, caused shoot ureide-N concentration to remain unchanged in aphid-injured plants when compared to uninfested plants. Because nitrate-N concentration was greater in aphid-damaged shoot tissue, we further conclude that nitrate-N accumulation was less sensitive to aphid injury than dry weight accumulation.

Keywords:

• soybean
• Glycine max (L.) Merrill
• soybean aphid
• Aphis glycines Matsumura
• insect feeding injury
• nitrogen
• ureide
• nitrate

ACKNOWLEDGMENTS

Research supported in part by a grant from the South Dakota Soybean Research and Promotion Council. The authors thank A. Rohweder, K. Anderson, and J. Zebill, and L. Draper for technical assistance. Mention of trade names or commercial products in this publication is solely for the purpose of providing information to the reader and does not imply recommendation or endorsement by the USDA. USDA offers its programs to all eligible persons regardless of race, color, age, sex, or national origin.

Notes

^†V1, first trifoliolate leaf expanded; V3, third trifoliolate leaf expanded, R2, full bloom; R4, full pod (after Ritchie et al., 1997).

^†Probability (t statistic) of a significant aphid treatment effect on dependent variables.

^†Probability (t statistic) of a significant aphid treatment effect on dependent variables within the V1 crop development stage infestation treatment.

^†Response determined by sequence of the three qualitative symbols for each element (after Jarrell and Beverly, 1981).

^‡Symbols represent more (↑), less (↓), or no change (0) in infested plants relative to uninfested control plants (t statistic, P = 0.1).