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ARS Home » Southeast Area » Raleigh, North Carolina » Plant Science Research » Research » Research Project #435675

Research Project: Strategies to Support Resilient Agricultural Systems of the Southeastern U.S.

Location: Plant Science Research

Project Number: 6070-11000-010-00-D
Project Type: In-House Appropriated

Start Date: Oct 24, 2018
End Date: Oct 23, 2023

Objective:
Objective 1. Assess conservation agricultural systems for the capacity to enhance productivity, reduce environmental impacts, build strong rural connections, and be profitable. Objective 2. Develop soil biological testing to improve nitrogen fertilizer recommendations for grain and forage crops. Objective 3. Identify crop stress-tolerance traits, assess germplasm and identify genetic sources of these traits for cultivar improvement. Sub-objective 3A. Identify sources of heat stress tolerance in soybean and wheat. Sub-objective 3B. Identify sources of ozone tolerance in soybean and wheat. Sub-objective 3C. Characterize root architecture under heat or ozone stress. Sub-objective 3D. Characterize the impact of heat, ozone stress, and management on the microbial communities associated with plant roots.

Approach:
Two long-term field experiments located at the Farming Systems Research Unit at Goldsboro, North Carolina, are the basis for the research on conservation agricultural system evaluation. One experiment compares conventional cropping, organic agriculture, integrated crop-livestock system, plantation forestry, and a naturalized fallow. Soil samples from all treatments will be tested periodically for soil organic carbon and nitrogen fractions, bulk density, water infiltration, and penetration resistance. Crop, animal, and timber production data will be used to assess the trajectory of sustainability from different farming systems. Intact root systems will be characterized for long-term management effects on microbial communities associated with roots using DNA technology (see below). The second long-term field experiment is an agroforestry study with the presence or absence of trees with the alleys planted to native warm-season grasses and tested for effects of harvest management. Forage, animal, and timber production data along with soil resource data will be used to assess the sustainability of the different types of forage utilization and type of shade management for cattle. Soil biological testing to improve nitrogen fertilizer recommendations will be conducted on research stations and on-farm trials. Treatments will be a series of different nitrogen rates to determine yield response of a crop to supplemental nitrogen. Soil biological activity will be determined with the flush of CO2 following rewetting of dried soil method and results used to develop site-specific fertilizer recommendations. Soybean and wheat germplasm selected in consultation with plant breeders will be screened for response to heat stress and elevated ozone. Plant response to heat stress will be assessed based on yield and harvest index using temperature gradient greenhouses and Air Exclusion System (AES) field technology to impose elevated temperature treatments. Plant response to ozone stress will be assessed based on foliar injury and yield using greenhouse chambers and open-top field chambers (OTC) to provide elevated ozone treatments. Genotype differences in biochemical (antioxidant enzymes and metabolites) and physiological (chlorophyll fluorescence, photosynthesis, respiration, and stomatal conductance) processes will be characterized to identify useful traits for phenotyping during development of cultivars with improved stress tolerance. Plants evaluated for heat stress and ozone tolerance will also be assessed for differences in root morphology and root-associated microbes. Root systems will be divided into root classes and assessed for genotype and treatment effects on biomass, diameter and length using high resolution scanners and WinRhizo software. Root associated microbes will be separated from roots and the rhizosphere DNA isolated. Bacterial/archaeal and fungal primer pairs will be used to amplify rhizosphere bacterial 16S rRNA genes and fungal Internal Transcribed Spacer regions (ITS1, ITS2). After sequencing, 16S rRNA sequences and ITSs will be analyzed to characterize genotype and stress effects on root associated microbial communities.