Evaluating the Effect of Potato Leafhopper Feeding on Biological Nitrogen Fixation in Alfalfa

View the project final report

Commodities

• Agronomic: hay

Practices

• Crop Production: greenhouses, nutrient cycling, tissue analysis, varieties and cultivars
• Education and Training: extension
• Pest Management: integrated pest management
• Soil Management: soil microbiology, soil quality/health

Increased nitrogen yield and content of forage crops results in increased profitability for growers. To meet biological nitrogen demands, alfalfa (Medicago sativa) depends primarily on nitrogen fixation, which is a process that eliminates nitrogenous fertilizer application. However, various biotic stressors can disrupt nitrogen fixation in crops. Determining the effect of pest feeding on nitrogen fixation in alfalfa provides growers with critical information to maintain high forage quality despite high pest pressure. Potato leafhopper (PLH; Empoasca fabae) is an economically important pest of alfalfa that alters numerous physiological processes in plants and could also disturb nitrogen fixation. Here I propose two main objectives to understand the effect of PLH feeding on nitrogen fixation in alfalfa. First, I will examine nitrogen assimilation sources in alfalfa in response to PLH feeding in the field by comparing two types of alfalfa: one strain capable of nitrogen fixation and one that is not. The aim is to understand if alfalfa can compensate for nitrogen losses from PLH feeding by taking up soil nitrogen. Next, I will study the response of PLH-resistant and PLH-susceptible alfalfa cultivars to pest pressure in terms of nitrogen fixation. I will determine which nitrogen source (atmospheric vs. soil) each cultivar relies on in response to PLH feeding and if PLH-resistant alfalfa can protect against nitrogen losses. Overall, my project will determine how PLH feeding alters nitrogen fixation in alfalfa and assess the effectiveness of using PLH-resistant varieties to reduce loss of nitrogen fixation for growers.

My research objectives are to:

1. Measure the effect of PLH injury on nitrogen fixation and soil nitrogen uptake in a field setting, and

2. Compare the response of resistant and susceptible alfalfa cultivars to PLH injury with regard to nitrogen fixation and soil nitrogen uptake.