S1079: Peanut Variety and Quality Evaluation for Development of Virginia-type Cultivars with High Oleic Trait, Flavor, and Rainfed Production
(Multistate Research Project)
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).