Performing Department
(N/A)
Non Technical Summary
Alfalfa is the third most widely produced crop in the U.S. and it can provide many environmental benefits, such as improving soil health, fixing atmospheric nitrogen, and enhancing biodiversity. Alfalfa is a broadly adapted crop that can be grown in hot desert environments to cold winter areas. However, alfalfa is prone to winter injury. The loss of forage and high cost of replacing alfalfa stands, up to $450 per ha, is cited as one of the major reasons for producers to select other forage crops. Following the particularly harsh winter of 2012-2013, more than 303,750 ha of alfalfa in Minnesota and 405,000 ha in Wisconsin were lost to winter injury. The proposed research will identify factors contributing to persistence of alfalfa and strategies to mitigate the losses of alfalfa stands, particularly in cold environments (Alaska, North Dakota, and Minnesota). This will allow the future development of more persistent cultivars and strategies to increase alfalfa production, resulting in improved profitability for farmers. The objectives of the project include: 1) Characterize alfalfa lines from the germplasm bank for winter hardiness, root architecture, and symbiotic N2 fixation capacity in northern climates; 2) Quantify forage yield and nutritive value of alfalfa and the potential ecosystem services associated with an increase in alfalfa acreage in the targeted regions (AK, ND, and MN), and 3) Assess the sustainability and environmental impact of the integration of alfalfa into the current crop and through outreach provide recommendations to producers on alfalfa varieties and management adapted to that region.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
Characterize alfalfa lines from the germplasm bank for winter hardiness, root architecture, and nitrogen fixation capacity in northern climates.Quantify forage yield, nutritive value, persistence, and root characteristics of commercial alfalfa varieties and advanced lines and determine the potential ecosystem services associated with an increase in alfalfa acreage in the targeted regions (Alaska, and northern North Dakota and Minnesota).Assess the sustainability and environmental impact of the integration of alfalfa into the current crop rotations at each target area and through outreach provide recommendations to producers on alfalfa varieties and management adapted to that region.
Project Methods
Objective 1.1.1 Genotyping of selected alfalfa germplasm collected in northern environments:Alfalfa accessionsfrom the USDA-ARS National Plant Germplasm System (NPGS), were identified with high winter survival scores, upright growth habit, disease resistance, and acid soil tolerance. Twenty five accessions were obtained from the NPGS. Each accession will be increased in the greenhouse during Oct.2024 to March 2025. Seeds will be germinated on wet filter paper then transferred topots and grown in greenhouse conditions for approximately 60 days. ng. Six flower racemes from approximately 50 plants (each with ~10 to 15 flowers) will be used for random intermating by hand pollination . Each plant will have a leaf removed for genotyping. Leaves will be placed in deep 96-well plates and frozen at -80°C, then freeze dried. The plates will then be shipped to DaRT for DNA extraction and genotyping using the alfalfa 3K DaRTag array. The DArTag marker technology uses a targeted amplicon sequencing approach in which a short stretch of sequence (81 bp) around the target SNPs are captured. Marker loci with data (total read count > 10) in >5% of the samples are retained for genotype calling and the genetic variation and population structure analysis.1.2 Phenotyping alfalfa selected lines for symbiotic nitrogen fixation traits:Symbiotic N2 fixation potential will be assessed after rhizobium inoculation using a panel of symbiosis phenotypes including root nodule number, nodule size, shoot dry weight, as well as rate of N2-fixation by acetylene reduction assay (ARA). To enable robust measurements of these comparisons, the assays will be performed in a controlled environment chamber (Conviron Gen-1000) and plants will be grown in a sand-vermiculite mix with N-free Jensen's medium to allow precise control of N levels. Rhizobia (Sinorhizobium meliloti USDA1106) will be grown in the laboratory and used to inoculate sterilized seeds before planting. To assess the differences in N2-fixation capacity under cold climates, two temperatures will be evaluated. These will include 21°C day and 17°C 8-hnight (ideal) and 12°C day, 8°C night (cold). Legumes inhibit nodulation and N2 fixation in response to soil residual N; to assess the ability of the germplasm to sustain N2fixation in the presence of residual N, N will be supplemented as NH4NO3 at three levels: 0, 4.5 and 9 g/m2. The SNF trait data be analyzed using multivariate statistics in R (PERMANOVA).?1.3 In field phenotyping of alfalfa accessions:The 25 accessions from seed increased and genotyped will be planted in 10-ftrows in Palmer and Fairbanks, AK, Fargo, ND, Grand Rapids, MN, and Columbia, MO in the spring of 2025. Forage will be harvested at 10% bloom and dry matter yield determined. Subsamples will be taken for analysis of forage nutritive value by NIRS. Persistence will be measured.In the spring of 2027, plants will be dug and roots will be cleaned prior to imaging and scoring. Images will be acquired either using RGB cameras using a black background or using a root imaging box to facilitate root segmentation. Images will be analyzed using Rhizovision explorer . Root systems will be and scored for root branching, crown injury, and the taproot diameter will be measured. Data collected will be analyzed using procedure MIXED of SAS 9.4 and R.1.4 Controlled environment phenotyping of alfalfa accessions for root system characteristics:Experiments will be imposed in 'deep-tubes' which allow for 75-cm of rooting depth. The tubes will be filled with a sand-vermiculite mix and will be imbedded in a custom-designed box with heating/cooling elements arranged horizontally at 10-cm depth increments starting at 5-cm from the top of the media. Thermocouples connected to CR1000 data loggers will be installed in the deep tubes to control and monitor the temperature gradient experienced by the roots.At harvest, shoots will be cut and dried and root system characteristics will be assessed after careful separation of roots from the sand-vermiculite mixture. We will float the entire root-system of each plant in custom-designed water-containing trays and image them in a custom-designed imaging box. Images will be analyzed using rhizovision explorer to extract broad range of root system traits. After imaging, roots will be dried at 50°C and root:shoot ratio as well as specific root length will be determined.Objective 2.2.1 Evaluation of commercial varieties for aboveground and belowground characteristics:Field trials will be established inPalmer and Fairbanks, AK, Fargo, ND, Grand Rapids, MN and Columbia, MO inMay 2025. The entries will include five to seven commercial varieties ( with extremely winter hardy scores) and experimental lines UMN 4561 (branched roots) and UMN4563 (deep taproots) . Non-nodulating ineffective alfalfa (InAgate) will be included in the trials as non-fixing check. Evaluations will include plant height, growth habit (prostate, erect), root morphology, forage yield, forage nutritive value, and 15N abundance in above ground biomass and roots. Samples for 15N abundance method will be taken in Sept.2026.2.2 Quantifying potential environmental factors that influence alfalfa growth and productivity :Prior to plot establishment each plot will be characterized for soil organic matter content , pH, and electrical conductivity in5-cm depth increments to 30-cm depth, and soil texture for the entire 0-30 cm depth increment. We will collect soil temperature and water content through the rooting zone with either sensors installed within the field trial footprint, or as components of the nearby meteorological stations. In the spring of 2026 and 2027, alfalfa plants within experimental and commercial screening trials will be rated for winter injury, including root severing and crown exposure due to frost heaving. Annually, plants within field trials will be monitored throughout the growing season for pathogen symptoms, identification, and damage.2.3 Quantify the potential of the screened calfalfa to participate as components in climate-smart cropping systems:Baseline soil samples will be collected from each location's trial footprint prior to trial installation in 2025.Soil samples will be collected in 5-cm increments to 30-cm depth and analyzed for total and organic C, active C , microbial biomass C, inorganic N (nitrate and ammonium,total N, and plant available pools of orthophosphate and K. Soil samples will be collected from each commercial trial plot again in the fall of 2025 and subsequent spring and fall of 2026 and 2027. Soil Cand Nmeasurements, along with the plant production and root measurements will be analyzed to estimate the in-season and between-season Cand Npool sizes associated with different alfalfa varieties and across different soil depths. Soil measurements will be analyzed using repeated measures and multivariate statistics to explore relationships across soil, plant, and nutrient data for each variety and location for the duration of the project.?Objective 3.For each location, we will evaluate which alfalfa varieties have the potential to contribute the most to farm enterprises, in terms of forage quantity and quality, N contributions to the system, and C stabilization in soils. We will communicate these recommendations to producers during annual field days and regional farmer events, held at each location, and through the development of extension publications and media.? Each extension/outreach activity will be followed up by a survey to determine advancement in knowledge. Questions specifically designed to evaluate the impact of results of this project will be included in on-site polls to farmers participating in field days, workshops, farm tours, and conferences. These polls will assess the outcomes in knowledge of project activities.