1a. Objectives (from AD-416):
Objective 1: Determine yield response and identify yield limiting factors of edible legume germplasm when grown under abiotic stress and managed using different production systems. Sub-objective 1A: Assess inoculant effects on winter survivability, root rhizobial biodiversity, nitrogen fixing capacities, and yield of direct-seeded advanced edible winter pea (Pisum sativum L.) cultivars in a winter wheat crop rotation. Sub-objective 1B: Identify novel pea germplasm with cold and drought tolerance, in the presence or absence of Rhizobium, to improve food-grade winter pea production across different agro-ecological environments. Objective 2: Enhance G x E x M to develop biotic stress-resilient edible legume cropping systems that improve sustainable production. Sub-objective 2A: Assess the G x E x M interactions of multiple bean genotypes to white mold under different tillage, fertilization and irrigation practices. Sub-objective 2B: Identify and determine Fusarium root rot genetic resistance and the effect of seed treatments on root rot severity, rhizobial formation and winter survival in winter pea under different agro-ecological environments.
1b. Approach (from AD-416):
Sub-objective 1A: Hypothesis: Winter peas will interact favorably with Rhizobium inoculants to improve winter survival, seed nutritional qualities, yield, and soil health. Approach: Ten food-grade, cold tolerant, winter peas will be grown at two locations. Presence of Rhizobium inoculant on emergence, root nodulation, chlorophyll content, plant height, root/shoot dry weight, root disease severity, rhizobial diversity, soil nitrogen, seed composition, and seed yield/quality over multiple years will be evaluated. Sub-objective 1B: Goal: Identify novel pea germplasm from worldwide collections useful for improving cold and drought tolerance in food-grade winter pea cultivars. Approach: Pea lines evaluated will be screened for cold tolerance (CT) under natural conditions. Lines with CT will be evaluated for drought and disease tolerance in seven rainfall zones. The five highest yielding lines with the best cold and drought tolerance across rainfall zones will be grown at the three lowest rainfall zones and presence/absence of Rhizobium inoculant on these lines evaluated. Sub-objective 2A: Goal: Identify G x E x M interactions that improve control of white mold disease of bean. Approach: Three tillage (conventional, minimum, and no-till) treatments will be evaluated in alternating strips across a field. Two irrigation treatments, 80 and 100 percent evapotranspiration, will be imposed at flowering through maturity. Eight lines will be assessed across tillage x irrigation combinations. Traits measured will include: emergence, stand vigor, flowering date, canopy porosity, lodging, canopy height, normalized difference vegetation index, canopy coverage, canopy temperature, disease incidence/severity, above ground biomass, yield, and seed weight. Sub-objective 2B: Goal: Identify genetic resistance and fungicidal seed treatment combinations effective against Fusarium root rot (FRR) species impacting winter pea across different precipitation zones. Approach: Twelve winter pea fields from six precipitation zones in Washington will be assessed for FRR at four growth stages and species identified. Pea lines from the Pisum Core Collection and cold-tolerant lines identified in Sub-objective 1B will be screened for resistance to the two major FRR species and association and bi-parental mapping populations used to determine quantitative trait loci associated with the resistance. Four winter pea lines with the best CT, resistance to FRR, and yield will be planted in three precipitation zones in Washington and treated with four fungicidal seed treatments to determine best management practices for FRR.
3. Progress Report:
This report documents progress for the project 2090-21000-003-00D, which began October of 2018 and continues research from 2090-21000-002-00D, “Developing Climate Resilient Crop Systems through G x E x M." Significant progress was made in support of Sub-objective 1A, concerning the effects of inoculating peas with commercial seed treatments that contain beneficial nitrogen-fixing rhizobacteria, we obtained several different inoculants from commercial sources for field trials that will be planted in Fall 2019. In support of Sub-objective 1B, a field trial was planted in Prosser, Washington, to evaluate 3,400 pea lines from the Pisum Collection for cold and drought tolerance. Fall emergence, frost damage, winter survivability, spring plant vigor and yield of these lines were determined. Several lines demonstrated outstanding cold and drought tolerance combined with excellent yield, which suggests they may be outstanding parents that can be used by breeders to improve cold and drought tolerance in winter pea. In support of Sub-objective 2A, a white mold nursery was established in 2018 that tested responses of 17 dry bean lines to white mold disease under optimum disease conditions (excess irrigation and high nitrogen fertility levels). One navy bean line had exceptional resistance due to disease avoidance from an extremely upright plant growth habit. A five-acre plot and smaller ½ acre plot were planted to beans and managed purposely to promote white mold disease in order to produce inoculum for future white mold disease nurseries. In 2019, six pinto bean varieties with different responses to low water (drought) and low fertility (low nitrogen) stresses were planted to see how they respond to white mold disease under different irrigation management. This trial is currently ongoing. In support of Sub-objective 2B, a root rot disease survey was conducted in the fall of 2018 to evaluate Fusarium species infecting winter pea roots. Pea plants from twelve commercial winter pea production sites were evaluated across a range of different rainfall zones in southeast Washington. Over 100 isolations of root rot pathogens were made from root tissues and pure cultures of these isolations were produced. We are currently in the process of identifying all the pathogens associated with these isolations. More than 450 different pea lines were screened for resistance to root rot caused by the fungus Fusarium avenaceum. Several lines were identified that had relatively high levels of disease resistance. Plants were selected from the most resistant white-flowered and purple-flowered lines and seed is being purified so these lines can be used as parents to develop more resistant new varieties.
1. Pea germplasm identified with improved resistance to Fusarium root rot. Fusarium avenaceum (Fa) is a fungus that causes severe root rot disease of pea throughout the major production regions of the U.S., including Idaho, Montana, North Dakota, and Washington. Currently there are no fungicides available against this disease and genetic resistance is the most effective and sustainable approach for disease management. ARS researchers in Prosser, Washington, evaluated 444 pea lines from the Pisum Collection and 28 popular commercial pea varieties for Fusarium resistance using a highly reliable greenhouse screening method. A total of 34 lines were identified that had greater levels of disease resistance than the other tested lines. These lines are being used by breeders to develop new pea varieties that have high levels of disease resistance coupled with important field and nutritional quality traits.
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