The Success of Organic and Other Sustainable Dual-Purpose Wheat Systems Depend on Access to Adapted Varieties

Final report for GS19-198

Project Type: Graduate Student
Funds awarded in 2019: $16,500.00
Projected End Date: 08/31/2022
Grant Recipient: Texas A&M University
Region: Southern
State: Texas
Graduate Student:
Major Professor:
Dr. Bill Pinchak
Texas A&M AgriLife Research
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Project Information

Summary:

Dual-purpose wheat cropping systems, which integrate livestock and crop production, are widespread in the Southern Great Plains region. But few of these systems are organic or managed using sustainable practices. A major roadblock to adoption of organic and sustainably managed dual-purpose systems is the identification and availability of wheat varieties adapted to this specialized and demanding purpose. Tolerance of low-N soil conditions, in conjunction with grazing tolerance, canopy architecture and early vigor that enable weed suppression, and consistent food-grade quality grain, are just several of the requirements. In this project, we propose to conduct a rigorous and properly controlled scientific evaluation of 15 diverse wheat varieties that have been utilized in regional wheat systems. All varieties will be tested in low and high-N conditions, and in simulated dual-purpose and grain-only management formats. The treatments will be evaluated for crop traits, including: canopy development and architecture; crop phenology; forage yield and nutritive values; and grain yield and quality parameters. This experimental structure and data collection plan will allow us to scientifically determine the most suitable varieties to recommend to producers in the short-term, but, more importantly, to discern the variation, relationships, and tradeoffs among measured traits critical in developing improved varieties. We expect the outcomes of the project will make organic and sustainable dual-purpose wheat systems more attractive, accessible, and economical to more producers, enhancing the quality of life for wheat and beef producers and society in this rural area. Dissemination of results to stakeholders is one of our primary objectives.

Project Objectives:
  • Assess canopy development and crop phenology;
  • Evaluate wheat forage yield and nutritive value with simulated grazing;
  • Quantify grain yield and end-use qualities;
  • Determine the variation, relationships, and tradeoffs among measured traits;
  • Disseminate results to stakeholders and the scientific community.

Cooperators

Click linked name(s) to expand/collapse or show everyone's info
  • Dr. Bill Pinchak (Researcher)
  • Dr. Dariusz Malinowski (Researcher)

Research

Materials and methods:

Our proposal was to conduct a dryland field study for two years, including the 2019-2020 and 2020-2021 winter seasons. We planned to conduct the study on a cooperating producer’s field near Vashti, TX, but issues with weeds at the site prevented that. Consequently, and to help strengthen our project outreach, we cooperated with personnel at the Oklahoma State University Southwest Research and Extension Center in Altus, Oklahoma to carry out the trial there in the 2019-2020 season. Planting and data collection were successful, though Covid-19 restrictions made travel to the site challenging after March 2020. Unfortunately, right before wheat flowering, a hailstorm destroyed the study and prevented collection of data at flowering and harvest. To accommodate ongoing Covid-19 restrictions on our activities, we chose to conduct the trail at one of our local Texas A&M properties in the 2020-2021 and 2021-2022 seasons. We received a 1-year extension of the project to complete a second iteration of the study in the 2021-2022 wheat production season.

 

The experiment was designed for multiple treatment factor comparisons: wheat varieties (15); fertilizer management systems (2) (organic compost applied at 1 ton/ac at approximately 41 kg N ha-1 prior to planting and conventional N split-applied at 71.6 kg ha-1), and biomass management systems (grain-only; dual-purpose). These were arranged in a split-split plot experimental design, with N management systems grouped within blocks, and wheat variety plots split in half for biomass management systems. Plots are relatively small (6 ft x 20 ft), comparable to typical wheat variety trial plots, to accommodate the large number of treatment factors and plots included. Soil samples were collected before planting from 0 to 15 cm and 15 to 60 cm depths and analyzed for fertility, especially forms of N. The organic compost was applied and incorporated into the soil just prior to planting each year. The conventional N (urea) was split-applied at planting (49.1 kg N ha-1) and just prior to the first hollow stem growth stage (22.5 kg N ha-1). Dual-purpose biomass management (integration of livestock grazing defoliation into a grain production system) was simulated by periodically mechanically mowing plots to a 5 cm stubble height prior to the first hollow stem stage of development, while the biomass in the grain-only plots was left untouched.

 

The timing of crop development, as determined by plant genetics interacting with management and environmental factors, can have large impacts on crop performance. Thus, crop progress through key developmental stages was assessed by making observations at four periods: early tillering (Zadok’s 20), first hollow stem (Zadok’s 31), anthesis (Zadok’s 65), and physiological maturity (Zadok’s 92). Canopy height was measured in conjunction with growth stage observations. Biomass samples were collected during the growing season to assess production, other forage qualities, and canopy development. Canopy cover measurements were taken concurrent with biomass measurements in the dual-use treatments

 

Dried biomass samples were ground to 1-mm for forage nutritive measurements. Forage nutritive value was determined by near-infrared reflectance (NIR) spectroscopy measurements of crude protein (CP), in-vitro dry matter digestibility (IVDM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) using established relationships. Total digestible nutrients (TDN) were calculated from ADF using this equation: TDN g kg-1 = [95.88 – (0.911 x ADF g kg-1)].

 

Grain yield was determined at physiological maturity using a small plot combine for harvest, with grain weighed in the lab. From each plot, 1000 seeds were counted and weighed to determine 1000-seed weight. A subsample of grain was ground and analyzed for N using combustion analysis. Grain protein was calculated by multiplying grain N content by 5.7, as indicated by the American Association of Cereal Chemists method 46-30.

 

Results are presented as means values and percent change in variables of interest. Statistical analyses of the entire study period and all variables have yet to be completed. Analyses will be performed using the SAS software. Analysis of variance (ANOVA) will be done using the MIXED procedure to determine variation within measured traits and interactions. Statistical contrast will be used for targeted treatment comparisons. To determine relationships and tradeoffs between pairs of measured traits, Pearson’s correlation coefficients will be calculated using the PROC CORR procedure. The PROC REG procedure will be used to perform multivariate regression analysis to examine the relationships among multiple traits. Upon completion of statistical analyses, at least one scientific journal article and an Extension bulletin will be submitted for publication in 2023.

Research results and discussion:

Reported are results from the 2020-2021 and 2021-2022 winter wheat production seasons. Results from the 2019-2020 season are not included, because the study was destroyed prematurely by a hailstorm in that year.  Location, management, treatments, varieties were the same in final two years.  Planting occurred on October 2, 2020 and October 8, 2021.

 

Precipitation (August-May) was markedly different between the 2020-2021 and 2021-2022 wheat production cycles. The 20-year mean precipitation from August to May for the study site is 491 mm. During the 2020-2021 wheat production year, precipitation was 538 mm (110% of normal). In contrast, the 2021-2022 production year total precipitation was 291 mm (59% normal), resulting in a pronounced year effect on most measured variables. A historic, record-breaking winter weather outbreak in February 2021 resulted in 11 consecutive days of below-freezing temperatures.

 

Forage standing biomass results from the dual-purpose systems for 2020-2021 and 2021-2022 are shown in Figure 1 and 2, respectively. These results are sums of total standing biomass harvested 3 times in 2020-2021 production season and 2 times in the 2021-2022 production season. Severe drought in 2021-2022 limited forage biomass production. Supplemental irrigation was applied on 1/14/2022 (25.9 mm) to prevent stand loss and again on 4/18/2022 (40.8 mm) to assure grain production. No supplemental irrigation was applied in the 2020-2021 production cycle. Forage samples were collected when sufficient standing biomass was present between December and early March, prior to the first hollow stem growth stage which normally occurs in early March in this region of the Southern Greta Plains. This represents the typical grazing period for dual-purpose winter wheat systems.  In 2020-2021 (Figure 1) total forage biomass prior to development of the first-hollow stem, across wheat varieties, averaged 1392 kg ha-1 with conventional fertilizer and 942 kg ha-1 with organic fertilizer. On average, there was a 32% decline in forage yield with organic fertilizer management, though the best performing wheat varieties with organic management produced more forage than the worst performing varieties with conventional management. Forage production values in the 2020-2021 season were lower than typically observed in dual-purpose wheat in this region due to challenging weather conditions. This included wet planting conditions in September (104 mm) that was 152% of average precipitation and a historic freeze from February 8 to 19, 2021.

 

Total forage biomass before first- hollow stem in 2021-2022 across all varieties receiving conventional fertilization was 848 kg ha-1 and 775 kg ha-1 with organic fertilization (Figure 2). Forage biomass production was 9% lower using organic fertilizer under severe drought conditions. Forage biomass production in 2021-2022 with conventional fertilizer was 39% less than during the 2020-2021 season, compared to a 17% decrease observed under organic fertilization. There were relatively minor treatment and variety differences in forage nutritive values in the dual-purpose systems (data not shown). Overall average forage nutritive value between organic and conventional systems were quite similar. Forage nutritive value was sufficient to support 1 kg average daily gains for stocker cattle in this region. Animal gains in both systems and across all varieties would not be constrained by nutrient concentration of the forage, but by overall forage available for grazing under the conditions of this study.

 

Weed control options are limited in organic wheat management systems and crop productivity is often limited by nitrogen availability. Providing more rapid and complete ground cover is an important character trait for wheat to better compete with weeds. Figures 3 and 4 show changes over time in percent ground cover for all 15 wheat varieties in the grain-only plots in both conventional and organic conditions for 2020-2021 and 2021-2022, respectively. Overall, average wheat percent ground cover exhibited bimodal patterns of increasing ground cover until December, then increasing again in February as wheat begins rapid spring growth. The maximum percent cover attained in both study years were impacted by adverse weather conditions. Historic low temperature freeze for 12 consecutive days in February 2021 left wheat leaves severely burned and limited growth rate  in early spring.  The exceptional drought during the 2021-2022 dramatically reduced above ground biomass production.  Overall percent ground cover across varieties was higher under conventional than organic fertilization throughout the 2020-2021 season.  Ground cover percentage where similar between fertilization practices in 2021-2022 season.  Between seasons, under conventional fertilization 2021-2022 ground cover was 8 to 13 percentage units lower than at comparable time points in 2020-2021. There is sufficient variation among varieties within and between fertilization type to warrant  further wheat variety investigation for germplasm suited for organic hard red wheat production systems in the Southern Great Plains.

 

Phenological development stage data presented as day of the year (DOY) are summarized for 2020-2021 in Table 1 and 2021-2022 in Table 2.  Average DOY to first hollow stem was 4 days later under organic than conventional fertilization in 2020-2021.  Six varieties FHS stage increased 6 or more days in the organic treatment.  In contrast, average DOY at anthesis and physiologic maturity differed by 1 day.  In the 2021-2022 wheat production year extreme drought increased time to FHS by 5 days and 1 day under conventional and organic fertilization, respectively.  While average day of anthesis was also delayed 5 days and days to physiologic maturity was shortened by 7 to 8 days under prevailing drought conditions.  There appear to be variety effects on the phenological development rate displayed all varieties tested based on genotype by fertility management by environment interactions that will be statistically analyzed to determine which of the tested varieties hold promise for use in organic hard red winter wheat dual-purpose and gain only systems.

 

Grain yield and quality are the primary drivers of gross sales receipts in wheat production systems.  Grain yield was markedly different between wheat production years in this study (Tables 3 and 4).   Variety, management, and fertilizer source all contributed to a yield range of 59.8 to 23.2 bu ac-1 in 2020-2021 production year and 27.4 to 8.8 bu ac-1in 2021-2022 (Table 3).  There are clear environmental effects on the yield differences between years as noted earlier.  Across all varieties in 2020-2021 conventional fertilizer practice averaged 45.8 bu ac-1 versus 34 bu ac-1 with organic fertilizer and a 25.8% yield differential.  Dual-purpose wheat management led to 7.5 (-16.4%) conventional and 5.8 (-15.1%) organic bushel yield decreases compared to grain-only management.  The 2021-2022 drought year yields (Table 4)  ranged from 17.2 to 13.5  bu ac-1 and were from 28 to 14.7 bu ac-1lower than 2020-2021 yields across fertilizer and management treatments.  Individual varieties experienced up to 70% yield difference between years.

 

Grain protein analysis for 2021-2022 have not been completed yet.  Some preliminary results suggest grain protein were much greater ( up to 40%)  across varieties and treatments than found in 2020-2021 (Table5).  Considering the severity and duration of drought increased grain protein content was expected.  Grain-only management and conventional fertilizer treatment grain protein content averaged 11.6% versus 9.28% for organic fertilizer.  Interestingly, differential response in grain protein among varieties to fertilizer type and management type were observed.  Further statistical analyses will determine are significant and biologically relevant for inclusion in wheat variety selection for organic production.

 

We submit that genotype by fertilizer type by management by environment interactions and differences among varieties we are observing suggest some varieties are better adapted for different systems and applications than others. These analyses are underway and will be included our upcoming extension and research publication in 2023.  Findings from research funded by this Graduate Student Grant will form a basis for future research initiatives to determine economic and environmental suitability and sustainability of producing organic hard red winter wheat in the Southern Great Plains dual-purpose and grain only production systems.

Figure 1 SSARE Final Report

Figure 2 SSARE 2022 Final Report

Figure 3 SSARE 2022 Final Report

Figure 4 SSARE 2022 Final Report

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1: Phenological data (day of the year) for 2020/2021 wheat varieties in grain-only and dual-purpose systems.

Variety

FHS

Anthesis

  Physiologic Maturity

 

Conventional

Organic

Conventional

Organic

Conventional

Organic

Green Hammer

70

70

103

102

143

143

Greer

69

71

100

101

141

144

LCS Chrome

74

79

108

108

148

148

Smith's Gold

70

71

105

104

146

144

Sturdy

74

78

104

103

148

146

SY Monument

75

82

107

105

147

146

SY Razor

70

78

103

101

149

148

TAM 113

71

74

107

108

148

149

TAM 114

70

76

105

105

147

148

TAM 115

71

77

109

110

151

149

TAM 204

69

75

103

103

152

149

TAM 205

73

77

105

103

144

144

TAM 304

70

76

102

104

145

143

WB 4699

79

78

107

105

147

144

Winterhawk

71

76

104

103

146

145

Average

72

76

105

104

147

146

 

 

Table 2: Phenological data (day of the year) for 2021/2022 wheat varieties in grain-only and dual-purpose systems

Variety

FHS

Anthesis

  Physiologic Maturity

 

Conventional

Organic

Conventional

Organic

Conventional

Organic

Green Hammer

76

70

112

110

136

133

Greer

77

68

105

107

135

133

LCS Chrome

78

81

112

113

144

141

Smith's Gold

72

74

111

109

141

144

Sturdy

81

83

112

111

145

144

SY Monument

86

84

113

111

141

137

SY Razor

68

74

105

106

136

140

TAM 113

76

71

112

112

141

141

TAM 114

81

78

112

110

145

137

TAM 115

72

77

113

111

144

138

TAM 204

74

76

106

108

137

135

TAM 205

78

83

110

110

141

141

TAM 304

71

77

112

109

137

136

WB 4699

81

83

112

111

137

137

Winterhawk

80

80

111

110

141

136

Average

77

77

110

110

140

138

 

 

Table 3: Grain yield (bu/ac) for 2020/2021 wheat varieties in grain-only and dual-purpose systems.

Variety

Grain-Only System

Dual-Purpose System

 

Conventional

Organic

Conventional

Organic

Green Hammer

32.8

37.4

33.2

25.1

Greer

45.8

27.5

40.2

33.2

LCS Chrome

51.5

32.4

36.3

23.2

Smith's Gold

43.3

33.2

41.0

31.6

Sturdy

32.1

25.9

30.7

23.4

SY Monument

52.0

38.0

48.9

26.9

SY Razor

28.6

24.1

27.8

23.9

TAM 113

59.8

35.9

38.6

28.3

TAM 114

51.9

46.5

48.2

35.4

TAM 115

47.4

40.7

39.8

27.7

TAM 204

37.7

25.0

31.1

24.4

TAM 205

47.1

35.7

40.2

26.8

TAM 304

48.0

29.1

39.9

37.0

WB 4699

41.8

34.4

35.6

29.7

Winterhawk

46.1

34.3

42.5

27.1

Average

45.8

34.0

38.3

28.2

 

 

 

 

 

 

 

 

 

 

Table 4: Grain yield (bu/ac) for 2021/2022 wheat varieties in grain-only and dual-purpose systems.

Variety

Grain-Only System

Dual-Purpose System

 

Conventional

Organic

Conventional

Organic

Green Hammer

17.0

16.8

16.6

16.3

Greer

15.3

12.8

14.2

11.7

LCS Chrome

20.9

11.9

21.0

10.8

Smith's Gold

16.3

12.2

12.5

13.3

Sturdy

10.1

9.1

13.9

12.6

SY Monument

17.1

12.0

16.6

19.8

SY Razor

14.0

15.7

8.8

11.8

TAM 113

19.4

18.0

17.7

12.9

TAM 114

12.5

14.5

11.9

13.5

TAM 115

27.4

15.1

19.1

14.6

TAM 204

19.0

13.7

16.5

15.1

TAM 205

14.7

15.1

14.5

14.3

TAM 304

12.3

12.8

14.8

9.2

WB 4699

24.4

16.9

19.9

17.7

Winterhawk

11.3

13.4

15.5

11.4

Average

17.2

14.0

15.9

13.5

 

 

 

 

Table 5: Grain protein concentration (%) for 2020/2021 wheat varieties in grain-only and dual-purpose systems.

Variety

Grain-Only System

Dual-Purpose System

 

Conventional

Organic

Conventional

Organic

Green Hammer

14.3

11.08

12.2

11.2

Greer

10.5

9.16

9.4

9.6

LCS Chrome

11.8

9.72

11.3

10.0

Smith's Gold

10.7

8.36

11.1

8.4

Sturdy

13.8

9.79

13.2

10.3

SY Monument

10.5

8.47

10.4

9.1

SY Razor

13.5

9.99

13.4

10.5

TAM 113

10.2

9.09

9.8

9.9

TAM 114

10.2

8.80

10.4

9.1

TAM 115

11.9

8.86

12.1

9.4

TAM 204

11.0

9.83

9.7

9.8

TAM 205

11.5

8.66

12.6

9.0

TAM 304

11.7

9.58

11.4

9.8

WB 4699

11.8

8.64

10.7

8.6

Winterhawk

10.34

9.18

10.2

9.4

Average

11.6

9.28

11.2

9.6

 

Participation Summary
2 Farmers participating in research

Educational & Outreach Activities

4 Consultations

Participation Summary:

Education/outreach description:

We completed the second full wheat production season in late June 2022.  Detailed statistical analyses and modeling are underway.  We will submit at least one scientific journal article and one extension bulletin in 2023.

Project Outcomes

Project outcomes:

N/A

Knowledge Gained:

N/A

Recommendations:

N/A

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.