Evaluation of NUE and WUE on Corn Hybrids With and Without Drought Tolerance in Irrigated and Dryland Production Systems Eric C. Miller Jeremiah L. Mullock, Jacob T. Bushong, and William R. Raun ASA, CSSA, & SSSA Annual Meetings Tampa, FL November 5st, 2013

Drought The 2012 drought, 597 counties in 14 states primary natural disaster areas (USDA, 2013). $14 billion in crop insurance indemnity payments (Congressional Budget Office, 2013).

Drought effects on corn

Transgenic trait/GMO Cold shock protein B gene Called ‘cspB’ Bacillus subtilis bacterium Cold shock proteins accumulate Act as RNA chaperones Bind and unfold tangled RNA molecules to promote normal function (Castiglioni et al., 2008) http://www.lhsc.on.ca/_images/Genetics/centraldogma.jpg

Conventional breeding Express native drought tolerant traits using marker assisted selection (Butzen and Schussler, 2009)

WUE x NUE interaction Dry soil = poor nutrient uptake Drought alters the root:shoot ratio Increased root respiration, increases nutrient solubility More root respiration, has the potential to increase nutrient uptake (Liu et al., 2004) http://www.monsanto.com/newsviews/pages/bt-corn-performance-in-us-corn-belt.aspx

Objective Evaluate N use efficiency (NUE) and water use efficiency (WUE) Drought tolerant and less drought tolerant corn hybrids Irrigated and rainfed production systems

Experiment sites Established in 2013 and will continue in 2014 3 replicates 4 row plots, 6.1 m long Soils: Efaw Norge: Fine-silty, mixed, active, thermic Udic Paleustolls Lake Carl Blackwell (LCB) Port: Fine-silty, mixed, superactive, thermic Cumulic Haplustolls, Oscar: Fine-silty, mixed, superactive, thermic, Typic Natrustalfs LCB Efaw

Experimental design: GxExM Genetics Drought tolerant Pioneer P1498: Optimum AQUAmax Monsanto 63-55: Droughtgard Less drought tolerant Pioneer P1395 Monsanto 62-09 Environment x Management Photo Courtesy of Jacob Bushong Irrigated production system Preplant N rates 0, 101, and 202 kg ha-1 Seeding rate 75,650 seeds ha-1 Rainfed production system Preplant N rates 0, 67, and 134 kg ha-1 Seeding rate 53,800 seeds ha-1

Statistical analysis Treatment Structure SAS PROC GLM Two way factorial with 4 levels of hybrid 3 levels of N rate Randomized complete block design Nested within production system SAS PROC GLM Analysis conducted by site and year

Grain yield and nitrogen use efficiency (NUE) Grain yield (Mg ha-1) Center two rows per plot Adjusted to 155 g kg-1 moisture NUE (kg kg-1) Grain yield kg ha-1 / kg ha-1 applied N fertilizer http://web.extension.illinois.edu/nwiardc/ eb270/20121015_6040.html

Water use efficiency (WUE) Cumulative WUE (kg m-1) Grain yield kg ha-1 / Evapotranspiration (ET; m) ET = +∆SWC + R + I – D Soil Water Content (SWC) Preplant and postharvest 1 m soil profile Rainfall (R) Mesonet Irrigation (I) Drainage (D) negligible Photo Courtesy of Tracy Wilson

Rainfall

------------------- Pr > F ------------------- Analysis of variance Main effects and interaction effects for grain yield, water use efficiency (WUE), and nitrogen use efficiency (NUE) at Efaw and Lake Carl Blackwell (LCB), 2013. Efaw LCB Grain Yield WUE NUE ------------------- Pr > F ------------------- Irrigation 0.002 0.008 0.006 0.001 0.005 Hybrid 0.297 0.248 0.301 0.292 0.351 0.566 N Rate 0.722 0.700 0.004 0.017 0.016 0.007 Irrigation x Hybrid 0.529 0.507 0.897 0.705 0.765 0.962 Irrigation x N Rate 0.503 0.570 0.231 0.027 0.026 0.012 Hybrid x N Rate 0.795 0.810 0.531 0.684 0.664 0.844 Irrigation x Hybrid x N Rate 0.084 0.074 0.367 0.548 0.501 0.698

Grain Yield

Hybrid differences: Efaw Single degree of freedom contrasts and differences of the means for grain yield (Mg ha-1), water use efficiency (kg m-1; WUE), and nitrogen use efficiency (kg kg-1; NUE) at Efaw, 2013. Grain Yield (Mg ha-1) WUE (kg m-1) NUE (kg kg-1) P > F Diff. Drought tolerant vs. Less drought tolerant 0.416 -0.485 0.503 0.314 0.361 -5.44 Monsanto vs. Pioneer 0.110 0.994 0.085 0.582 0.204 7.69 Droughtgard vs. AQUAmax 0.116 1.38 0.079 1.06 0.100 14.4

Hybrid differences: LCB Single degree of freedom contrasts and differences of the means for grain yield (Mg ha-1), water use efficiency (kg m-1; WUE), and nitrogen use efficiency (kg kg-1; NUE) at Lake Carl Blackwell (LCB), 2013. Grain Yield (Mg ha-1) WUE (kg m-1) NUE (kg kg-1) P > F Diff. Drought tolerant vs. Less drought tolerant 0.928 0.084 0.837 0.012 0.839 1.10 Monsanto vs. Pioneer 0.065 0.832 0.107 0.179 7.58 Droughtgard vs. AQUAmax 0.139 0.916 0.170 0.116 0.275 8.58

NUE x WUE: Efaw

NUE x WUE: LCB

Conclusions Irrigation significantly increased grain yield, WUE, and NUE at both sites Increased N rates resulted in higher yields for the irrigated production systems Regardless of hybrid, improvements in WUE resulted in increased NUE The Monsanto Droughtgard hybrid yielded ~1 Mg ha-1 more than the Pioneer AQUAmax hybrid at both sites (~$70) Lack of drought tolerant hybrid differences in 2013 could have been from an unseasonably wet growing season

Questions?