Project Number: 2090-21000-002-00-D
Project Type: In-House Appropriated
Start Date: Jun 14, 2016
End Date: Oct 14, 2018
Anticipated increases in global population coupled with climate change and rising demand for limited natural resources compel the development of more efficient and sustainable systems of crop production to meet existing and future nutritional requirements. Agricultural production systems characterized by the rotation of edible grain legumes with cereal grains have been crucial sources of nutrition to human diet for several millennia. Primary edible grain legumes grown in U.S. production systems include dry bean, dry pea, lentils, and chickpeas, which are cultivated in rotation with cereal grains including wheat and barley. These crops have complementary nutritional qualities, with grain legumes having relatively high seed concentrations of lysine and low concentrations of the sulfur-containing amino acids methionine and cysteine, while cereal grains tend to have low concentrations of lysine but high concentrations of sulfur-containing amino acids. Crop rotations also contribute to more sustainable control of plant diseases and weeds. Legume roots are routinely colonized by beneficial “rhizobacteria”, which chemically convert atmospheric nitrogen to nitrogenous fertilizer. This association between legume and rhizobacteria especially contributes to sustainable crop production, as the fertilizer is used by the legume crop and also remains in the field as residual fertilizer for small grain production. Several sources of variance including genetics (G), environment(E) and management practices (M) contribute to yield loss and the differences, or “gaps”, observed bewteen actual yield and yield potential. The ability to develop climate resilient cropping systems that consistently produce stable and high yields requires understanding how these sources of variance and their interaction effects impact crop yield. Objective 1. Develop strategies to exploit interactions of GxExM for climate-resilient crop systems that reduce the gap between potential yield and farmer yield. Sub-objective 1A. Determine yield response and identify yield limiting factors of grain legume germplasm when grown under drought stress and managed using different tillage systems. Sub-objective 1B. Identify pre-emergence herbicides and agronomic practices for the management of weeds in edible grain legume-cereal grain cropping systems characterized by different soil moisture environments. Sub-objective 1C. Examine the effects of host plant, rhizobacteria, soilborne pathogens, and their interactions on biological nitrogen fixation. Research will be conducted across laboratory, greenhouse and field facilities maintained by the research unit and collaborators. Participating ARS personnel and collaborators have expertise in agronomy and weed science, plant pathology and microbiology, and plant breeding and genetics.
Sub-objective 1A. Determine yield response and identify yield limiting factors of grain legume germplasm when grown under drought stress and managed using different tillage systems. Hypothesis: Dry bean genotypes interact with tillage management to affect yield performance under drought conditions. Eight pinto bean genotypes with varying drought tolerance will be tested in a field previously sown to wheat. A split, split block with four replications with irrigation level the main plot, tillage level the split plot, and genotypes the split, split plot will be used. Irrigation will be manipulated to impose a terminal drought stress. Conventional tillage and strip tillage will treatments will both include use of a nonselective herbicide. Variables will include plant biomass, soil compaction, soil moisture, measures of plant stress and various yield components. Sub-objective 1B. Identify pre-emergence herbicides and agronomic practices for the management of weeds in edible grain legume-cereal grain cropping systems characterized by different soil moisture environments. Hypothesis a) Timing of herbicide application when available soil moisture and likelihood of precipitation is greater impacts weed control in chickpea. Four herbicides will be tested at three application timings; 4 and 2 weeks prior to seeding chickpea, and post-plant, preemergence. Herbicide treatments will be replicated in a randomized complete block. Soil moisture will be monitored gravimetrically for 4 weeks after each application. Weed control and chickpea tolerance will be determined by taking weed counts and visual control ratings at 3 and 6 weeks after planting (WAP) and crop stand counts at 4 WAP, and chickpea seed yield. Hypothesis b) Roller-packing impacts performance of pre-emergence herbicides in chickpea in dry soil conditions. Four herbicide combinations applied post-plant, pre-emergence will be tested in chickpea with and without roller-packing. Experiments will be designed as a split block with herbicide as the main treatment and roller packer as the split treatment and each treatment replicated four times. Half of each plot will be roller-packed immediately after herbicide applications. Weed control and chickpea injury will be evaluated and visually compared to a non-treated check. Analysis of variance will be used to statistically separate treatment effects in all experiments. Sub-objective 1C. Examine the effects of host plant, rhizobacteria, soilborne pathogens, and their interactions on biological nitrogen fixation. Hypothesis: Rhizobacteria strains, soilborne pathogens and cultivar class significantly impact biological nitrogen fixation and yields of pea and chickpea genotypes. The interactions between the root rot pathogen Fusarium solani, commercial rhizobacteria inoculants, and foliar applications of phosphorous acid, on nitrogen fixation and rhizobial colonization of the most popular dry pea cultivars grown in Washington and Idaho will be assessed in field and greenhouse trials. Plants will be evaluated for elemental content, plant height, dry shoot/root weight, root disease severity, nodulation and yield.