RESPONSES OF WHEAT GENOTYPES TO PHOSPHORUS IN ORGANIC AND CONVENTIONAL CROPPING SYSTEMS IN THE PACIFIC NORTHWEST

Julia L. Piaskowski, Washington State University, Pullman, WA, Chris Hoagland, Purdue University, West Lafayette, IN and Kimberly Garland Campbell, Wheat Genetics, Quality, Physiology and Disease Research Unit, USDA Agricultural Research Service, Pullman, WA

Phosphorus (P) is arguably the most limiting macronutrient in the world. Dwindling resources of easily mineable P, along with water quality concerns and recent spikes in fertilizer prices, have lead to a renewed interest in improving phosphorus use efficiency in crops.

IntroductionResults

Materials and Methods

Conclusions

Acknowledgements

Boyd: 2010 Organic

Lind: 2009/10 conventional

Benge: 2009 Organic

Experimental block (n=4)

High P (20 lbs/a)

Low P(0 lbs/a)

AM fungi

No Inoc

No Inoc

AM fungi

Alpowa OtisBlanca Grande Louise

Louise AlpowaOtis Walworth

Walworth Blanca Grande

1950 1960 1970 1980 1990 2000 2010 20200

100

200

300

400

500

600

700

800900

Figure 1: Average Price and Price Index of Triple Su-perphosphate (TSP, 0-46-0)

TSP (0-46-0) ($/ton)

Price index 1982=100

year

$/to

n

• Field trials were conducted in organic and conventionally-managed locations across Washington state dryland production region in 2009 and 2010 to test the responsiveness of five spring wheat (Triticum aestivum) cultivars to phosphorus fertilizer and inoculation with arbuscular mycorrhizal (AM) fungi.

• Each site consisted of two fertilizer treatments, two inoculation treatments, and five cultivars arranged in split-split plot design with four blocks.

• The fertilizer treatment consisted of no additional fertilizer and 20 pounds per acre of P2O5, applied as either inorganic ammonium polyphosphate (11-37-0) or OMRI-certified fertilizers from Perfect Blend® and Nature Safe®

Figure 2: Location of Field Sites and Experimental Design

Data from the ERS

Map: Spatial Climate Analysis ServiceOregon State University

• Funding was provided by the USDA-OREI Grant (Accession #0218862) and a Washington State University BioAg Seed Grant

• Land and consultation provided by the WSU Lind Dryland Experimental Research Station, Gregg Beckley of G&L Farms and by Pat and and Les Boyd

P trt Inoc P trt x Inoc P trt x Cultivar

Inoc x Cultivar

P trt x Inoc x Cultivar

SPAD (chlorophyll)         2010  Plant height (cm) 2009          Tillers/m2           2010Stripe rust infection (%)         2010  Test weight (lbs/bu)       2010    Yield (Kg/Ha) 2010 2009    09,10,10**    1000 kernel weight (g)   2009 09/10      Protein (% in seeds)     2009    Sedimentation (mL)       2009    P, leaves at tillering (mg/g)     09/10 2010    P, leaves at grainfill       2009    P, leaves at senescence     2010   2010 2009P, seeds 2009   2009 09/10   2009Cu (seeds, mg/g) 2010 09/10   2009    Fe (seeds)     2010 09/10    Mn (seeds)   2010        Zn (seeds) 2010 2010 2009 2009    MANOVA: all traits  09,10,10*** 2009   2010 2010 2010MANOVA: agronomic 09/10 2009   2010 2010  MANOVA: all nutrients  All 2009    09/10    MANOVA: micronutrients 09,10,10*** 2010 2009 09/10    2009MANOVA: P data 09,10,10*** 2009   09/10    

Table 1: Heat Map of Statistical Significance at a = 0.10*

*The effect of cultivar is significant for all traits and sites at a = 0.01; those results are omitted because cultivar differences alone are not the objectives of this study. ** All sites except organic 2010 (Boyd) had significant differences for this test.*** All sites except conventional 2010 (Lind) had significant differences for this test

All Sites3 Sites

Organic & ConventionalOrganic only

Conventional only

0

5

10

15

20

252009 Conventional (Lind)

AlpowaBlanca GrandeLouiseOtisWalworth

Bush

els/

acre

0

5

10

15

20

25

30

35

402010 Organic (Boyd)

Phosphorus Treatment (Low, High)0

5

10

15

20

25

30

35

402010 Conventional (Lind) Yield

Phosphorus Treatment (Low, High)

Bush

els/

acre

0

5

10

15

20

25

2009 Organic (Benge)

Figure 3: Changes in Yield by Phosphorus Fertilizer

Cu (mg/hectare)

Organic 2009 (Benge)

Cu (mg/g seed)

Figure 5: Boxplots of Changes in Seed Fe Due to P Fertilizer

Conventional 2010 (Lind)

Figure 4: Boxplots of Changes in Seed Cu In 2009 Organic Field Site Due to P Fertilizer

Alpowa

Blanca Grande

Louise

Otis

Walworth

Alpowa

Blanca Grande

Louise

Otis

Walworth Alpowa

Blanca Grande

Louise

Otis

Walworth

AlpowaBlanca Grande

Louise

OtisWalworth

**Louise: p = 0.0015

**Louise: p = 0.0647

**Blanca Grande0.0003

**Louise: p = 0.0806

**Blanca Grande0.0180

**Otis: p 0.0022

**Louise: p = 0.0205

**Blanca Grande0.0433

**Alpowa: p 0.0058

p=0.0217

p=0.0732

p=0.0550

p=0.0018

p<0.0001

p=0.0037

nonsignificant

All Photos: Julia Piaskowski

• The statistically significant P-values are broadly spread over multiple variables, main effects and interactions. No obvious pattern is evident across years, sites or management regimes.

• The observed response to phosphorus is cultivar-specific and in some cases, site-specific.

• The locally adapted cultivar Louise consistently yielded higher than the others and responded to additional P fertilizer despite high soil test P levels during 2010 (12-24 ppm, bicarbonate assay)

• Blanca Grande, a hard white wheat from California, performed erratically, undergoing a yield loss under additional fertilizer in the organic field sites.

• Differences in seed Cu concentration were cultivar specific for Benge, 2009, but those differences became biologically and statistically insignificant once adjusted for yield per unit area.

• Differences in seed concentration of Fe were also cultivar and site-specific. Additionally, those effects are not correlated with Cu or other micronutrients within the same site.

• P fertilizer resulted in an increase in P content in early growth tissue, a growth stage in which tissue analysis for P have been shown to identify P deficiencies. These effects were amplified by AM fungi, resulting in increased [P] in the high P samples and decreased [P] in the low samples, possibly due to increased biomass from growth stimulation.

Low P High P33003400350036003700380039004000410042004300

Lind 2009: Change in Leaf [P] during tillering due to P fertilizer and AM

fungal inoculation

no inoculationmycorrhizal

mg

P/g

drie

d le

af ti

ssueMycorrhizal fungal

arbuscle infecting Alpowa

Experiment at the Boyd Farm, 2010, (Certified Organic Land)

p = 0.0537