S1079: Peanut Variety and Quality Evaluation for Development of Virginia-type Cultivars with High Oleic Trait, Flavor, and Rainfed Production
(Multistate Research Project)
S1079: Peanut Variety and Quality Evaluation for Development of Virginia-type Cultivars with High Oleic Trait, Flavor, and Rainfed Production
Duration: 10/01/2018 to 09/30/2023
Statement of Issues and Justification
In the Virginia-Carolinas (VC) region, peanut is an important cash crop with annual acreages ranging from 175,000 to 230,000. National production increased substantially in the past five years, although acreages were only slightly raised in South Carolina and unchanged in Virginia and North Carolina. For example, average production across the region during 2007 – 2011 was 233 × 103 tons while during 2012 – 2016 it increased to 288 × 103 tons. This is in great part due to the new and more productive Virginia-type cultivars released after screening through the Peanut Variety and Quality Evaluation (PVQE) multi-state projects S-1038 and S-1059, which were effective from 2007 through 2018 (Fig. 1). Specifically, development of high yielding cultivars with multiple disease resistance like ‘Bailey’ (Isleib et al., 2011) and ‘Sugg’ (Isleib et al., 2015) helped growers maintain unprecedented state-wide average yields of approximately 4,000 pounds per acre since 2012, when certified seed production of Bailey ramped up and acreage of Bailey exceeded 75% of the total peanut land in the VC region. Since Bailey’s release as part of the S-1038 project, multi-state S-1059 resulted in the release of ‘Sullivan’, ‘Wynne’, ‘Emery’, and ‘Bailey II’ Virginia-type cultivars with great yield potential, disease resistance plus with high oleic acid oil chemistry.
Over 80% of peanut acreage in the VC region is grown every year with Virginia-market type peanut cultivars, for which Virginia and the Carolinas are lead producers in the U.S.A. and world. Desirability of the Virginia-market type versus other peanut types, e.g., runner and Valencia, is related to its kernel size and flavor, and the industry that evolved in the VC region around this particular type of peanut. Virginia-type peanuts have bigger kernels than other types, for which farmers receive premiums. For example, one kilogram of seed has on average 1830 seeds for runners and Valencia, and 1055 for Virginia. The Virginia-type peanuts are almost twice the weight of the runner or Valencia-type and have high content of extra-large kernel (ELK) and super extra-large kernel (SELK) content for which farmers receive premiums. In an average of $355 per ton load of farmer stock, the farmer receives about $15 - 18 of that value is due to ELK. For shelled goods, the largest of the extra-large kernels carry the highest value of any of the Virginia-type kernels. These kernels, called SELK, provide the backbone for the gourmet processing trade, which sets Virginia apart from the other peanut growing states since the majority of these firms are located in Virginia. Anecdotally, Virginia-type peanuts have good flavor when grown in the VC region. Indeed, roasted peanuts with desirable flavor and textures are important for the Virginia-type peanut markets. Quality of roasted peanut flavor is complex, with roasted peanut volatiles being composed of hundreds of different compounds (Johnson et al., 1988; Williams et al., 2002). Sensory evaluation is generally preferred for flavor quality assessment, but for small samples, this is not always possible.
Figure 1. Genetic gain in crop value since the beginning of the Peanut Variety and Quality Evaluation multi-state testing. Crop value was calculated from the USDA formula combining yield and grading of the farmer stock peanut. The polynomial relationship suggests a crop value increase of $10 per year per acre. (See attachment)
Consumers recognize the size of kernels attributable to the Virginia-type peanut and desire the crunchiness and flavor for which they are known. Ultimately, the combination of peanut type and growing environment contributed to the establishment of the specific peanut markets in the VC region, with in-shell peanut trade, the gourmet peanut market, export markets, as well as the edible peanut being the predominant markets.
The peanut breeding project at the NCSU is responsible for the development of high yielding, high ELK and SELK, and disease resistant Virginia-type cultivars for the VC region. The PVQE project is responsible for multi-state testing of the best breeding lines of the breeding project. Finally, the breeding project leader makes release decisions based on the PVQE data. The PVQE has provided multi-state variety testing for Virginia-type cultivar development for 50 years (1968 – 2018) (S-1059, S-1038, S-1003, S-140). With leadership at the Virginia Tech’s Tidewater Agricultural Research and Extension Center, Virginia Tech, North Carolina State University, the National Peanut Shellers Association, the North Carolina Peanut Board, and the South Carolina Peanut Board jointly fund the PVQE. The project also provides a forum for various segments of the peanut production, shelling, and processing industries to express the industry’s emerging needs through the PVQE Advisory Committee annual meetings. Created in 1968, the PVQE is unique among established peanut programs at universities throughout the U.S.A., and it is internationally recognized as a strong multi-state data support program for the Virginia-type cultivar development.
Among the priorities of the current S-1059 multi-state project, development of Virginia-type cultivars with the high oleic oil chemistry was determined as the most important for the VC region. Increased oleic and decreased linoleic fatty acid content, the so-called ‘high oleic’ trait improves peanut shelf life, reduces rancidity, and increases safety for consumers. Earlier research showed that high oleic peanuts have improved oxidative stability and longer shelf life than non-high oleic peanut. For example, roasted in shell peanuts with 50% oleic acid reached a Peroxide Value (PV) of 20 meq kg-1 (as indication of oxidation) after only 2 wk of storage. However, the peanut with 80% oleic fatty acid did not reached 20 meq kg-1 until after 40 wk of storage (Mozingo et al., 2004). In the VC region where edible peanut markets are predominant, replacement of normal-high oleic with high oleic cultivars was imperative. As part of the S-1059 project expiring in 2018, four high yielding high oleic cultivars have been released, Sullivan, Wynne, Emery, and Bailey II, and certified seed is already available for commercial production for Sullivan and Wynne. Due to a freezer disaster in which purified breeder seed of Emery was destroyed, its seed increase is concurrent with that of Bailey II in spite of having been released two years earlier. Since the deployment of S-1059, all breeding lines in the NCSU breeding project and the PVQE testing have the high oleic oil chemistry.
Drought significantly limits peanut production in the U.S.A. and the world, and significant research efforts towards improvement of drought tolerance in peanut have been done worldwide (Hubick et al., 1986, 1988; Wright et al., 1988; Matthews et al., 1988; Rucker et al., 1995; Puangbut et al., 2009; Songsri et al., 2009). In the VC region, precipitation distribution is irregular and often deficient during the summer months. Concurring with increasingly higher summer temperatures, this led to frequent droughts which may affect peanut yields in otherwise “rainy” years (Singh et al., 2014). Peanuts require uniform precipitation of 25 to 75 mm per week depending on the growth stage. Otherwise, prolonged lack of precipitation and heat significantly reduces yield and quality of the seed, and the oleic fatty acid content decreases (Balota et al., 2015). In particular, ELK and SELK require ample amounts of water to fill the seeds. Indeed, none of the existing Virginia-type cultivars grown in the VC region is drought tolerant, even though significant variability for drought related traits was identified among the peanut breeding lines submitted for PVQE testing (Balota et al., 2012; Rosas-Anderson et al., 2014). Supplementing water through irrigation is an option, but only 10% of the peanut land is irrigated in the VC region. Therefore, improving peanut yield and quality during drought episodes in rainfed production is now a priority for peanut production in the region and the U.S.A.
In 2016, the National Peanut Board in collaboration with NIFA provided grant money for drought research through the AFRI Foundational Program, Critical Agricultural Research and Extension (CARE) priority area. The PVQE project leader received the AFRI-CARE grant. AFRI Physiology of Agricultural Plants awarded a second grant for drought research in the VC region. While these awards coincide with the need for drought research, they are limited to only three years of research while the development of cultivars with improved drought and heat tolerance may take ten years or more. However, they are instrumental in development of robust protocols, for further drought and heat research, within a new PVQE project after the current S-1059 expires in Sep 2018. Within previous years of the PVQE testing, we have identified and released two breeding lines expressing drought tolerance, i.e., relatively high yields under drought, but more work is needed for the development of commercial cultivars (Balota et al., 2015; Tallury et al., 2014).
Related, Current and Previous Work
The multi-state Project S-1059 ‘Peanut Variety and Quality Evaluation Program for Development of Virginia-Type Cultivars with High Oleic Trait’ lead by Dr. M. Balota will end Sep 30, 2018. The objectives were to (1) examine yield and quality of high oleic Virginia-type peanut breeding lines in replicated tests within key growing areas of the VC region; (2) develop a database for Virginia-type peanut genotypes allowing knowledge-based selection for release of adapted cultivars that will meet all of the criteria for market success; and (3) find Virginia-type peanut lines that would be well adapted to the southernmost part of the VC growing region and be suitable for development into cultivars. As has been its history, the program has and continues to address and solve these issues. In not yet five years, the program has addressed, and for certain aspects exceeded its expectations. For example, four new Virginia-type cultivars with high yield, quality, and high oleic trait were released in 2013, 2015 and 2017 after being regionally tested in the PVQE project: Sullivan, Wynne, Emery, and Bailey II. Sullivan, named for a former peanut extension specialist, and Wynne, named for a former peanut breeder at NCSU, were released in 2013. Emery was released in 2015 and named for D.A. Emery, peanut breeder at NCSU in the 1960’s. Derived by backcrossing from the successful cultivar Bailey, Bailey II was released in 2017. These new cultivars are highly productive and have excellent disease resistance packages. For example, Bailey has medium resistance to all four major regional diseases: early leaf spot caused by Cercospora arachidicola Hori, late leaf spot caused by Cercosporidium personatum (Berk. & M.A. Curtis) Deighton, Cylindrocladium black rot (CBR) caused by Cylindrocladium parasiticum Crous, M.J. Wingf. & Alfenas, Sclerotinia blight (SB) caused by S minor Jagger, and tomato spotted wilt (TSW) virus caused by Tomato spotted wilt tospovirus (Isleib et al., 2011). In particular, Wynne and Emery are extra large-seeded peanuts with high content of jumbo pods and SELK. Release of all four cultivars was the direct result of PVQE testing in Virginia, North Carolina, and South Carolina, in collaboration with Dr. Thomas G. Isleib, the peanut breeder at NCSU, and Drs. Jay Chapin, Scott Monfort, and Dan Anco, peanut specialists at Clemson University.
None of these cultivars has drought or heat tolerance based on preliminary field-testing under rainout shelters with controlled soil moisture; but some breeding lines with improved drought tolerance, i.e., yield in dryland plots, were identified through PVQE testing and released (Table 1). No other breeding program in the country is aimed at the development of drought tolerant Virginia-type cultivars for the VC region, as proposed in this project. For example, a search of the CRIS database resulted in identification of several peanut breeding and genetics projects in Florida (0216938, 0199617, 0199437, and 0177295), Texas (0214725, 0161373), Georgia (0199874), and New Mexico (0216351) but they are developing runner, Spanish, and Valencia-type peanut. The new project differs significantly from S-1059 and all the other CRIS projects by shifting the interest towards development of high oleic and drought tolerant Virginia-type cultivars. In the classic paper on stress tolerance by Rosielle and Hamblin (1988), these authors caution against selecting to minimize the difference between yield in the stress and non-stress environments, demonstrating how it is better to select for increased mean yield across both environments. In the proposed work, we plan of following their example, and evaluate the breeding lines under irrigated and non-irrigated relatively large field trials, and under much more smaller plots under rain exclusion shelters where drought will be controlled in a field setting.
To examine the yield, grade, quality, maturity, insect and disease response of high oleic advanced Virginia-type peanut breeding lines in comparison with commercial cultivars in replicated tests within the VC region
To develop a database for tested genotypes allowing knowledge-based selection for release of high oleic cultivars that will also meet all other criteria for market success within each state
To find high oleic Virginia-type peanut lines with suitable flavor for development into cultivars, which are well adapted to the VC growing region.
To find high oleic and drought tolerant peanut lines which are well adapted for rainfed peanut production in the VC encountering high temperature and unpredictable droughts.
For Objectives 1 and 2, replicated experimental tests will be conducted at multiple locations in Virginia (1 location), North Carolina (3 locations), and South Carolina (1 location). Entries will be lines with desirable traits selected from breeder tests conducted independently in North Carolina and Virginia. Within the PVQE testing, all selected Virginia-type lines will be compared to standard cultivars currently in production. All genotypes in PVQE tests will be thoroughly evaluated for quality factors and judged against industry standards. Data will be analyzed and presented at the PVQE Advisory Committee meeting and State Grower meetings before release. Plots will be seeded with a precision vacuum planter in 36-inch rows at four seed per foot of row in all tests. Plots will be two rows trimmed to 35 feet and treatments will be replicated two times as dictated by resource allocation analysis and practical concerns such as seed supply and travel budget. In advance of the planting window, seed will be packaged at the Tidewater AREC and delivered to the cooperating state(s). Treatments will be arranged in lattice designs. Soil fertility, herbicide, insecticide, and fungicide inputs will be made according to Extension recommendations.
In order to address Objective 3, we will be using gas chromatography analysis of volatiles for routine screening and will use sensory evaluation when sufficient size samples are available (Rodriguez et al., 1989; Vercellotti et al., 1992). Samples will be made available from field plots under Objective 1.
Chemical analysis of flavors using SPME-GCMS
Solid phase micro-extraction gas chromatography mass spectrometry will be used with a Shimadzu QP2020 Ultra GCMS fitted with a SPME autosampler and refrigerated autosampler following procedures described by Baker et al. (2002) and Reed et al. (2002). Briefly, samples of blanched peanuts 10g will be air roasted using an air column in a Freshroast 500 coffee roaster using the low setting and stirring until a medium roast is reached (L=50-51). Peanut samples will be weighed and placed in 20 ml glass headspace vials. Headspace extraction will use 2 cm solid phase microextraction fibers containing carboxen-divinylbenzene-polydimethylsiloxane by exposing fiber to headspace for 30 min at 45C. Volatiles will be desorbed into a SPME inlet liner. Volatiles will be identified by comparing mass spectra with NIST and Wiley libraries and published Kovats Index data (Flavornet database). Volatiles will be quantified using internal standard. Volatiles of importance to positive peanut flavor attributes will be quantified to generate a sum of total peanut-flavor volatiles per sample. As there is no single character impact compound in peanuts (Crippen et al., 1992; Klevorn and Dean, 2018), this will provide an estimation of how the different lines compared in flavor profiles. Amino acids are involved in peanut flavor via Maillard and other chemical reactions and Klevorn and Dean (2018) have shown the complex relationship between free amino acids and roasting, so it is difficult to use an analytical approach to determine flavor precursors in peanuts. However, it is well known that some peanut varieties have superior flavor after roasting. It is of importance to include assessments of peanut flavor in line selections to ensure that roast peanut quality is evaluated early in the line selection process.
Flavor acceptability and quality of peanut varieties will be determined using sensory evaluation with hedonic and quantitative descriptive analysis procedures. Replicate lots of mature peanuts will be obtained for flavor analysis. Peanuts will be roasted to medium roast (L=50-51) using a commercial forced draft oven (Rational SCC WE62; Rational AG, Germany). Flavor attributes will be assessed using trained consumer panelists. Panels of at least 75 consumers will be provided with 10g samples of roasted peanuts and will be asked to rate overall acceptability, peanut flavor acceptability and texture acceptability on 9 point scales. If differences in sensory characteristics are observed with trained sensory quantitative descriptive analysis panels will be used to characterize what different attributes in more detail (Johnsen et al. , 1988; Braddock et al., 1995; Pattee et al., 1995; Baker et al., 2003). Human subject experiments will be approved by the Virginia Tech Institutional Review Board.
To address Objective 4, we propose to use rainout shelters and precise irrigation in small field trials available at Tidewater AREC (Fig. 2). Each shelter can accommodate 24 plots 3 m long by 0.9 m wide. Therefore, the drought evaluation can accommodate 12 varieties replicated four times (twice under each shelter), testing ten best-performing lines selected for a second or greater year of PVQE regional testing along with two selected checks for drought tolerance. Water deficit stress will be imposed by covering the plots with the shelters at beginning pegging growth stage. Drought tolerance will be evaluated based on yield after harvest and plant wilting symptoms during vegetation. Wilting will be assessed visually and using remote sensing as described by Balota and Oakes (2017). Currently, a graduate student is developing more complex methods for prediction of drought tolerance in peanut from image analysis. If successful, these methods can be implemented not just in the rainout shelter screening, but in the screening of regular PVQE plots across the region. This high throughput phenotyping will be performed with ground and aerial platforms using RGB and infrared sensors for detection of plant stress.
Figure 2. Far and close images of peanut plots grown in the field under rain exclusion shelters to induce drought stress. (see attachment)
Virginia Tech personnel will manage field trials from planting through harvest at three locations in North Carolina, and one location in Virginia. For greater efficiency, plot planting, harvesting, and maintenance in South Carolina will be performed by staff at the Edisto Research and Education Center in Blackville, SC. Complete quality evaluation will be performed by Virginia Tech personnel within the PVQE program at TAREC. Seed of new high oleic lines will be initially provided by the peanut breeder at the NCSU and later, depending on availability, by Clemson University and Virginia Tech. Existing trucks, tractors, planters, combines, sprayers, computers, insect monitoring equipment, laboratory space, experiment farm acreage, peanut grading, drying, and storage facilities will be used to implement this study. A complete cleaning, sizing, shelling, and grading facility is available within the PVQE program at TAREC. Freezers for germplasm storage are also available at TAREC as is equipment for seed treatment. Data from all trials will be subjected to appropriate statistical analysis for evaluation. The plots under the rainout shelters will be evaluated for visual symptoms of drought stress, in addition to yield and grading. Wilting will be visually assessed as described by Luis et al. (2016) using a score identified in Fig. 3. Wilting timing will also be recorded and drought tolerant lines will be considered those with longer time to initial wilting symptoms (Devi et al., 2010) and also with high yields.
Figure 3. Scores proposed to be used for drought symptoms (wilting) evaluations in drought-induced rainout plots. 1 = healthy plants, no symptoms of drought stress; 2 = upper branches start wilting; 3 = whole plants wilted; 4 = upper canopy is drying; 5 = entire canopy severely wilted. (see attachment)
This research will insure that the peanut industry in the VC region will have access to desirable high oleic and drought tolerant Virginia-type cultivars. Timely results will become available to all segments of the peanut industry each year. Stakeholders for this project include breeders, producers, extension agents, consumers, retailers, and shellers. A multi-state approach is the best mechanism to meet the research and educational needs of these groups. The PVQE program will coordinate testing in Virginia and the Carolinas, and will be aligned with the needs of shellers, manufacturers, and processors in the development of high oleic and drought tolerant cultivars.
Measurement of Progress and Results
- Annual publication of reports of agronomic data on high oleic lines tested at five locations through the PVQE program. Data will give comparisons of lines to standard cultivars to determine suitability for the in-shell and roasted peanut markets. Results will include growth habit, plant height, yields, grades, pods in different size classes, and projected market value. For the rainout shelters, wilting severity and initial timing will be recorded and included in publications. Disease and insect resistance/susceptibility data will be included
- Reports on quality data of high oleic lines tested at five locations through the PVQE Program will be published annually. Data will give quality comparisons of kernel blanching for the different size classes, calcium content of seed, fatty acid composition, seed size distribution, mill outturn, appearance of kernels, flavor, pod brightness, cooking qualities, suitability for roasting, suitability for peanut brittle, etc. These data coupled with the agronomic data are essential for determining whether a breeding line will be acceptable to various segments of the peanut industry and have the potential to succeed in the market place.
- Presentation of data will be made to the PVQE Advisory Committee as well as at appropriate industry and professional meetings
- Papers on the high oleic trait and drought tolerance of the breeding lines and cultivars will be published in appropriate scientific journals.
- Data will be sufficient to make knowledge-based decisions for high oleic and drought tolerant cultivar releases with good adaptation to the various areas of the VC growing region.
Outcomes or Projected Impacts
- Determination of the suitability of high oleic and drought tolerant breeding lines to meet the needs of various segments of the peanut industry will be made.
- Development of new high oleic and drought tolerant Virginia-type cultivars will conform to different standards compared to older cultivars.
- New high oleic and drought tolerant breeding lines will be tested as made available through the NCSU Peanut Breeding Program.
- Thorough testing of new high oleic and drought tolerant cultivars prior to their release will assure that they perform well from agronomical prospective for farmers and have the high oleic characteristics desired by shellers, manufacturers, and consumers.
Milestones(0):Breeder Tests will be conducted in North Carolina, and high oleic lines tested therein will be selected for PVQE Testing. Lines selected for comparison and advancement become available for further testing. (VT and NCSU)
(0):Advanced lines with the high oleic characteristic will be tested for agronomic characteristics, drought tolerance, adaptability to the growing areas, and physiological qualities for use by all segments of the VC peanut industry. Elite line(s) will be considered for release as a cultivar(s); Research will be presented and published. (VT and NCSU)
(2019): Seed will be increased for elite line(s) selected for the high oleic, good flavor and slow wilting characteristic. Release decision will be made or line(s) selected for further testing. Seed will be made available for the Virginia Crop Improvement Association as appropriate. (VT)
(2019): Elite line(s) with high oleic, good flavor and slow wilting characteristic will be annually selected for release approval. Elite Line(s) will be chosen for release as cultivar(s) (VT and NCSU)
Projected ParticipationView Appendix E: Participation
Findings will be published by the investigators in their annual reports (hardcopy, web, and CD), discussed in production meetings, used to update harvest information provided by the state Peanut Production Guides, and published in appropriate refereed journals. Data will be scrutinized by the PVQE Advisory Committee annually and pertinent information will be presented to the V-C Peanut Advisory Committee every year.
Virginia will serve as the lead state for this project. Virginia Tech will provide salary, fringe benefits, and general operating support for the Project Leader and lead technician. Each participating state will be expected to contribute financially to the project by transferring funds to Virginia Tech for partial support of technical and clerical personnel, travel, and supplies associated with the research.
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