2021 Progress Made Possible Through Oklahoma Peanut Commission and National Peanut Board Support

• A total of 44 breeding lines and reference cultivars were evaluated at the Caddo
  Research Station for agronomic characteristics and soilborne diseases (Sclerotinia
  blight and pod rot).
• The runner trial included Lariat, FloRun ‘107’, Southwest Runner, IPG 914, ACI 080,
  ACI 476, ACI 3321 and 10 breeding lines from USDA-Agricultural Research Service. The Spanish/Valencia trial
  tested OLé, Schubert, Span 17, IPG 3628, Valencia C, six USDA-ARS Spanish breeding
  lines and four New Mexico State University Valencia breeding lines. The Virginia trial
  evaluated 12 entries: Jupiter, ACI 351, Contender, Comrade and two and six breeding
  lines from North Carolina State University and USDA-ARS, respectively.
• The Spanish/Valencia plots were dug 148 days after planting (DAP). Runner and
  Virginia plots were dug 166 DAP. Environmental conditions were unfavorable for
  Sclerotinia blight until October. Moderate to low levels of pod rot were observed in the
  advanced breeding line/cultivar trial.
• Numerically, the top runner entries for revenue and yield were Lariat ($787 per acre)
  and ARSOK R96-8 (3,993 pounds per acre), respectively. Little Sclerotinia blight and
  pod rot were observed.
• No significant differences were observed among entries in the Spanish/Valencia
  trial for revenue per acre and yield. The top entries numerically for revenue and yield
  were Span 17 ($561 per acre, 2,565 pounds per acre) and OLé ($556 per acre, 2,615
  pounds per acre), respectively. Moderately low levels of pod rot were observed.
• In the Virginia trial, the breeding line ARSOK V99 had the highest numerical crop value
  and yield ($767 per acre and 3,630 pounds per acre, respectively). Entries differed
  significantly in distribution of pod size classes by weight and pod sizes (number per
  ounce). Moderate to moderately low levels of pod rot were observed.

A major goal of the ARS peanut research program in Stillwater is to develop and release
high-oleic peanut cultivars for the Southwest with improved yield, disease resistance and seed characteristics. In 2021, we evaluated commercial and advanced breeding lines of runner, Spanish/Valencia and Virginia peanuts in small plots at Oklahoma State University's Caddo Research Station in Fort Cobb. The objectives of these field studies were: 1) to compare advanced breeding lines to commercially available cultivars for agronomic characteristics, such as yield and seed qualities, and resistance to soilborne diseases, and 2) to evaluate a selection of Virginia entries for pod rot resistance in fields where soilborne levels of the pathogens causing peanut pod rot were promoted by planting susceptible genotypes.

 

Methods and Field Conditions for Evaluating Advanced Breeding Lines and Cultivars

A total of 44 breeding lines and reference cultivars (17 runner, 15 Spanish/Valencia and
12 Virginia market types) were evaluated. Runner and Virginia peanut market types were each grown and evaluated separately, but Spanish and Valencia entries were combined in the same field and analyzed together. All advanced breeding lines were high oleic. Each entry was planted at a density of five seeds/ft in plots consisting of two 15-foot-long rows with 36-inch-wide beds. A randomized complete block design was used by dividing the field into four sections (blocks) to account for potential disease gradients and environmental variables. All plots were planted on May 14, 2021. The Spanish/Valencia entries were dug on Oct. 8 (148 days after planting) and threshed on Oct. 15. The runner and Virginia fields were dug 166 days after planting on Oct. 26 and threshed on Oct. 29. A total of 3,254- and 3,409-degree day heat units (in  ahrenheit) accumulated for the Spanish/Valencia and runner/Virginia trials, respectively.

 

The pod rot nursery was planted one month later on June 17 to reduce the number of
volunteers, and plots were dug on Oct. 5. After pod rot nursery plots were rated, pods were left in the field to retain pathogen inoculum. Additional water was applied to all plots 17 times (total 9.25 inches) between May 28 and Oct. 4 using a center pivot system.

 

All plots were inoculated with 0.25 grams of Sclerotinia minor sclerotia on Sept. 7. Fields were managed for weeds, foliar diseases and southern blight (caused by Athelia rolfsii) following Extension recommendations but were not managed for Sclerotinia blight, pod rot or nematodes. Entries were evaluated for Sclerotinia and southern blight on Sept. 27 in the Spanish/Valencia plots and on Oct. 22 for the Virginia and runner plots. Disease incidence was measured by counting the number of 6 inch-sections within each plot that had symptoms of Sclerotinia blight and southern blight. All plots were examined for pod rot within three hours of digging. Environmental conditions in 2021 were not favorable for Sclerotinia blight due to little rainfall in September (total of 0.58 inches) in addition to +3-4°F above-average temperatures in September and October (Table 1). Little southern blight was observed, but moderate to moderately low
levels of pod rot were observed in the Spanish/Valencia and Virginia trials.

 

Peanut grades were determined by following USDA-Agricultural Marketing Service guidelines and using two 200-gram samples from each plot. One 500-gram sample per plot was used to determine pod sizes in the Virginia entries. Yield was adjusted by factoring in the area lost by plots in the path of the center pivot wheels. Data were analyzed using one-way ANOVA in PROC GLIMMIX of SAS (version 9.4). The Type I error rate for pairwise comparisons of breeding lines and cultivars was controlled at α = 0.05 using the ADJUST=SIMULATE option.

 

Performance of the Runner Market Type Entries

Seventeen runner peanut entries were evaluated (Table 2): high-oleic cultivars Lariat, ACI 080, ACI 476, ACI 3321 and IPG 914; the Sclerotinia blight-susceptible and resistant cultivars FloRun ‘107’ and Southwest Runner, respectively; and 10 breeding lines from the ARS-Stillwater peanut program. Statistical differences were found among runner entries for yield and most shelling characteristics. Numerically, the top two runner entries for crop value or revenue, a combined measure of yield and seed grade, were Lariat ($787 per acre) and ARSOK R96-8 ($774 per acre). ARSOK R96-8 and Southwest Runner had the highest yields at 3,993 and 3,860 pounds per acre, but the grades for both these entries were significantly lower (at 69%) than the other topyielding entries, Lariat and ARSOK R95-1 (75% and 74%, respectively). Little Sclerotinia blight was  observed, even in the highly susceptible control FloRun ‘107’ (10%).

 

Performance of the Spanish/Valencia Market Type Entries

Six Spanish breeding lines from ARS-Stillwater and four Valencia lines from New Mexico State University were evaluated in addition to cultivars Valencia C, OLé, Schubert, IPG 3628 and Span 17 (Table 3). The 2021 contract price for Valencia peanuts was $750 per ton (N. Puppala, pers. communication), but all entries were analyzed using the Spanish contract price of $600 per ton to facilitate comparisons between market types. No statistical differences were found among the Spanish and Valencia entries for revenue and yield per acre, but there were significant differences for all seed characteristics (Table 3). OLé, ARSOK lines S105-3E and S96-5 and Span 17 had the highest numerical yields (≥2565 pounds per acre). ARSOK S104-2E and Span 17 had the highest numerical seed grades (≥73%). Moderately low levels of pod rot were observed. Valencia C, NM16-42 and NM-M7 (all ≥25%) had more pod rot than ARSOK lines S105-4E and S104-3E (≤ 3.5%).

 

Performance of the Virgina Market Type Entries

A total of 12 Virginia peanut entries were evaluated (Table 4 and table 5): Jupiter and high-oleic cultivars ACI 351, Comrade and Contender; two early maturing lines from North Carolina State University, N15041 and N17045; and six USDA-ARS breeding lines. The Virginia entries differed statistically in revenue per acre, yield and grade. The entry with the highest value and yield was ARSOK V99 ($767 and 3,630 pounds per acre), followed by Contender ($690 and 3,364 pounds per acre). Numerically, Comrade had the highest grade at 72%, followed by ARSOK lines V103-1, V101-1 and V99 (70-71%). Little Sclerotinia blight was observed, and the susceptible control Jupiter had only 14%  disease. The Virginia entries differed significantly in pod size and distribution of pod sizes (Table 5). Comrade, ARSOK lines V103-3 and V103-1, and ACI 351 had the largest percentage of super jumbo pods (>70%). The smallest percentage of super jumbo pods were observed in Contender and ARSOK V101-1 (40% and 38%, respectively).

 

Pod Rot in Virginia Entries

In 2021, more pod rot was observed in the advanced breeding line disease trial than in the pod rot nursery (Table 6). The month-long difference in planting dates may have contributed to the different levels of pod rot. In the 2021 cultivar/breeding line trial, ARSOK lines V103-3 and V103-1 had the least pod rot. The susceptible cultivar Jupiter consistently had the most pod rot over multiple trials. Levels of pod rot in Comrade fluctuated among fields and years.

 

Average Performance over the past three years (2019-2021)

Nine runner, seven Spanish and four Virginia entries were evaluated from 2019 through 2021 (Table 7). When data from multiple years are combined, significant differences in Sclerotinia blight, yield and grade were found among the runner entries. The highest numerical yields were obtained from Lariat and ARSOK R96-8. ARSOK R96-8 also had low levels of Sclerotinia blight in addition to relatively low seed grade. Among the Spanish entries, the highest numerical yield and grade were found in ARSOK S96-5 and Span 17, respectively. The four Virginia entries (Jupiter, Contender, Comrade and ACI 351) did not differ significantly in Sclerotinia blight or yield. Comrade’s seed grade (70%) was significantly higher than Jupiter’s (66%).

 

Additional Acknowledgments

We thank Angie Harting and Lisa Myers at USDA-ARS and Robert Weidenmaier, Harley Houston and Brennan Leighton at the Caddo Research Station for invaluable technical support. Seed for several commercial lines were originally provided by Birdsong, Golden and the International Peanut Group. Breeders N. Puppala (NMSU) and J. Dunne (NCSU) provided advanced lines.