Location: Sugarbeet and Potato Research
Project Number: 3060-21650-001-002-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2018
End Date: Dec 31, 2022
(1) Assess nitrogen fixation and residual nitrate for a range of pea and lentil lines and cultivars grown in the Northern Plains to allow pulse breeders to identify and breed for higher nitrogen fixing varieties. (2) Determine nitrogen fixation response in lentils from starter potassium plus sulfur fertilizer with and without inoculant. (3) Evaluate the effects of granular inoculant, peat powder seed coat inoculant, and double inoculant (granular plus peat powder, peat powder at 2x rate) on pea nitrogen fixation, residual nitrate-nitrogen, yield, and protein.
The study’s overall goal and specific objectives will be accomplished with plot trials at multiple locations, using the 15-N natural abundance method to quantify fixed nitrogen and soil testing to measure residual soil nitrate-N pools. Given that soil moisture and hence weather conditions are known to affect nitrogen-fixation amounts, we propose running studies for three years (2019-2021), to increase the robustness of our findings. Ten varieties and/or lines of each crop will be grown in a complete randomized block design with four replicate plots at two locations. Within one week of seeding, soils will be sampled to 90 cm in 30-cm increments in 12 representative plots (two subsamples per plot), dried and analyzed for nitrate-N colorimetrically. Above ground legume tissue will be harvested at full pod stage, and three to five reference plants located as close as possible to the pulse biomass sampling area will be collected. All plant tissue will be dried, ground and analyzed for 15-N and total N at the UC Davis Isotope Laboratory. Within one week after harvest, soil will be sampled in each plot for residual soil nitrate-N concentration and nitrate pools calculated. Genotypes showing potential to increase N-fixation will be used in the breeding program to develop new breeding lines and varieties that have greater N-fixation. Once structured genetic populations are developed, molecular markers useful for selection will be identified and used to aid the breeding process. Additional experiments will also be established with different fertilizer treatments to assess whether starter potassium plus sulfur fertilizer will affect nitrogen fixation in lentil. We will also assess whether nitrogen-fixing microbial inoculant type will affect nitrogen fixation and residual nitrate-N levels by growing two common pea varieties in a randomized complete block design with four replicates, using one of five treatments: a control, granular inoculant, peat powder seed coat inoculant, granular plus peat inoculant powder, and twice the rate of peat inoculant powder.