1. 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

2. 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).

3. Drought effects on corn

4. 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)

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

6. 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)

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

8. 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

9. 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

10. 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

11. 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
eb270/ _6040.html

12. 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

13. Rainfall

14. ------------------- 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

15. Grain Yield

16. 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

17. 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

18. NUE x WUE: Efaw

19. NUE x WUE: LCB

20. 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 could have been from an unseasonably wet growing season

21. Questions?