Virginia-type Peanut Research Articles

Phenotypic Dissection of Drought Tolerance in Virginia and Carolinas within a Recombinant Inbred Line Population Involving a Spanish and a Virginia-Type Peanut Lines

Peanut (Arachis hypogaea L.) is a rainfed crop grown in both tropical and subtropical agro-climatic regions of the world where drought causes around 20% yield losses per year. In the United States, annual losses caused by drought are around $50 million. The objective of this research was to (1) identify genetic variation for the normalized difference vegetation index (NDVI), canopy temperature depression (CTD), relative chlorophyll content by SPAD reading (SCMR), CO2 assimilation rate, and wilting among recombinant inbred lines (RILs) derived from two diverse parents N08086olJCT and ICGV 86015, to (2) determine if the physiological traits can be used for expediting selection for drought tolerance, and (3) experimental validation to identify lines with improved yield under water-limited conditions. Initially, 337 lines were phenotyped under rainfed production and a selected subset of 52 RILs were tested under rainout shelters, where drought was imposed for eight weeks during the midseason (July and August). We found that under induced drought, pod yield was negatively correlated with wilting and CTD, i.e., cooler canopy and high yield correlated positively with the NDVI and SPAD. These traits could be used to select genotypes with high yields under drought stress. RILs #73, #56, #60, and #31 performed better in terms of yield under both irrigated and drought conditions compared to check varieties Bailey, a popular high-yielding commercial cultivar, and GP-NC WS 17, a drought-tolerant germplasm.

Dryland Field Performance and Disease Assessment among Runner and Virginia-Type Peanut Genotypes

Dryland Field Performance and Disease Assessment among Runner and Virginia-Type Peanut Genotypes

Volatile Compound Profiles of Raw and Roasted Peanut Seeds of the Runner and Virginia Market-types

The unique flavor of peanuts that develops during roasting is the primary driving force for the consumption of peanut products. Although rarely consumed raw, the raw state of the peanut contains the precursors involved in the transformations that lead to the distinct flavor development in roasted peanuts. Volatile compounds extracted from the headspace above raw and roasted peanut samples of the runner and virginia market types by solid phase microextraction were characterized using two-dimensional gas chromatography coupled with time-of-flight mass spectrometry. The roasting treatment and peanut market-type each had a significant impact on the types and concentrations of small molecular weight compounds found. Among 361 sample components detected, 290 compounds were found to be significantly different between the raw and roasted treatments (p < 0.05). The roasted samples contained pyrazines, pyrroles, thiazoles, and furans. Alcohols were the primary compounds found in the raw peanut samples. Additionally, 107 compounds were found to differ significantly between roasted runner and virginia-type peanuts. Virginia-type peanuts contained higher levels of linoleic acid oxidation products, such as 2-octenal, hexanal, and 1-octen-3-one. More significant distinctions in volatile compounds were recognized between runner and virginia market types than previously observed. In total, this study reported 119 volatile compounds that have not previously been reported in roasted peanuts, including 11 furans, seven pyrroles, five pyridines, and 12 pyrazines.

Initiation of genomics-assisted breeding in Virginia-type peanuts through the generation of a de novo reference genome and informative markers.

Virginia-type peanut, Arachis hypogaea subsp. hypogaea, is the second largest market class of peanut cultivated in the United States. It is mainly used for large-seeded, in-shell products. Historically, Virginia-type peanut cultivars were developed through long-term recurrent phenotypic selection and wild species introgression projects. Contemporary genomic technologies represent a unique opportunity to revolutionize the traditional breeding pipeline. While there are genomic tools available for wild and cultivated peanuts, none are tailored specifically to applied Virginia-type cultivar development programs. Here, the first Virginia-type peanut reference genome, "Bailey II", was assembled. It has improved contiguity and reduced instances of manual curation in chromosome arms. Whole-genome sequencing and marker discovery was conducted on 66 peanut lines which resulted in 1.15 million markers. The high marker resolution achieved allowed 34 unique wild species introgression blocks to be cataloged in the A. hypogaea genome, some of which are known to confer resistance to one or more pathogens. To enable marker-assisted selection of the blocks, 111 PCR Allele Competitive Extension assays were designed. Forty thousand high quality markers were selected from the full set that are suitable for mid-density genotyping for genomic selection. Genomic data from representative advanced Virginia-type peanut lines suggests this is an appropriate base population for genomic selection. The findings and tools produced in this research will allow for rapid genetic gain in the Virginia-type peanut population. Genomics-assisted breeding will allow swift response to changing biotic and abiotic threats, and ultimately the development of superior cultivars for public use and consumption.

Multilocation Evaluation of Virginia and Runner -Type Peanut Cultivars for Yield and Grade in Virginia–Carolina Region

The peanut is mostly grown in semi-arid tropical regions of the world, characterized by unpredictable rainfall amounts and distribution. Average annual precipitation in the Virginia–Carolina (VC) region is around 1300 mm; however, unpredictable distribution can result in significant periods of water deficit and subsequent reduction in yield and gross income. The development of new peanut cultivars with high yield and acceptable levels of yield stability across various water-availability scenarios is an important component of the peanut breeding program in Virginia and the Carolinas, where the large-seeded Virginia-type peanut is the predominantly grown market type. In addition, the simultaneous use of runner cultivars developed in the dryer southeastern region has been proposed as a practical solution to limited irrigation availability in the VC region. Still, the identification and adequate utilization of available commercial cultivars with the best combination of yield, drought tolerance, and gross income is more immediately beneficial to the peanut industry, yet this assessment has not been carried out to date. The aim of this study was to identify cultivars that maintain high yield and grade, therefore gross income, across a wide range of environmental conditions. We evaluated five commercially available Virginia and runner-type peanut cultivars for pod yield stability using multilocation trials over four years across 13 environments. Additive main effects and multiplicative interaction (AMMI) and different stability approaches were used to study genotype (G), environment (E), and their interaction (G × E) on pod yield. Pod yield stability was specifically assessed by using the Lin and Binn approach, Wricke’s ecovalence, Shukla’s stability, and the Finlay–Wilkinson approach. The combined analysis of variance showed highly significant effects (p ≤ 0.001) for genotypes, environments, and G × E for pod yield. The environments varied in yield (2840–8020 kg/ha). Bailey, Sullivan, and Wynne are Virginia-type cultivars. The grade factors SMK, SS, and TK changed with water regime within both market types. Among the runner cultivars, TUFRunner 297 presented high mean productivity; however, it showed specific adaptation to limited environmental conditions. Based on different stability approaches, this study concludes that Sullivan and Bailey are the most stable and adaptable cultivars across the testing environments, whereas Wynne exhibited specific adaptability to some environments. These findings have important implications for peanut cultivar recommendations in terms of meeting peanut industry standards for yield, grading quality, and breeding progress.

Understanding variation in oleic acid content of high-oleic virginia-type peanut

Contamination at the FAD2B locus due to inadequate screening protocols is the primary cause of sporadic, insufficient oleic acid content in Virginia-type peanut. The high oleic trait in peanut is conditioned by loss-of-function mutations in a pair of homeologous enzymes and is well known to improve the shelf life of peanut products. As such, the trait is given high priority in current and future cultivars by the North Carolina State University peanut breeding program. For unknown reasons, high oleic cultivars and breeding lines intermittently failed to meet self-imposed thresholds for oleic acid content in internal testing. To determine why, a manual seed chipper, crude DNA isolation protocol, genotyping assays for both mutations, and a web-based SNP calling application were developed. The primary cause was determined to be contamination with normal oleic seeds resulting from inadequate screening protocols. In order to correct the problem, a faster screening method was acquired to accommodate a higher oleic acid threshold. Additionally, results showed the mutation in one homeolog is fixed in the program, dig date had no significant effect on oleic acid content, and minor modifiers segregating within the program explained 6% of the variation in oleic acid content.

Identification of consistent QTL for time to maturation in Virginia-type Peanut (Arachis hypogaea L.)

BackgroundTime-to-maturation (TTM) is an important trait contributing to adaptability, yield and quality in peanut (Arachis hypogaea L). Virginia market-type peanut belongs to the late-maturing A. hypogaea subspecies with considerable variation in TTM within this market type. Consequently, planting and harvesting schedule of peanut cultivars, including Virginia market-type, need to be optimized to maximize yield and grade. Little is known regarding the genetic control of TTM in peanut due to the challenge of phenotyping and limited DNA polymorphism. Here, we investigated the genetic control of TTM within the Virginia market-type peanut using a SNP-based high-density genetic map. A recombinant inbred line (RIL) population, derived from a cross between two Virginia-type cultivars ‘Hanoch’ and ‘Harari’ with contrasting TTM (12–15 days on multi-years observations), was phenotyped in the field for 2 years following a randomized complete block design. TTM was estimated by maturity index (MI). Other agronomic traits like harvest index (HI), branching habit (BH) and shelling percentage (SP) were recorded as well.ResultsMI was highly segregated in the population, with 13.3–70.9% and 28.4–80.2% in years 2018 and 2019. The constructed genetic map included 1833 SNP markers distributed on 24 linkage groups, covering a total map distance of 1773.5 cM corresponding to 20 chromosomes on the tetraploid peanut genome with 1.6 cM mean distance between the adjacent markers. Thirty QTL were identified for all measured traits. Among the four QTL regions for MI, two consistent QTL regions (qMIA04a,b and qMIB03a,b) were identified on chromosomes A04 (118680323–125,599,371; 6.9Mbp) and B03 (2839591–4,674,238; 1.8Mbp), with LOD values of 5.33–6.45 and 5–5.35 which explained phenotypic variation of 9.9–11.9% and 9.3–9.9%, respectively. QTL for HI were found to share the same loci as MI on chromosomes B03, B05, and B06, demonstrating the possible pleiotropic effect of HI on TTM. Significant but smaller effects on MI were detected for BH, pod yield and SP.ConclusionsThis study identified consistent QTL regions conditioning TTM for Virginia market-type peanut. The information and materials generated here can be used to further develop molecular markers to select peanut idiotypes suitable for diverse growth environments.

Sodium azide induced high-oleic peanut (Arachis hypogaea L.) mutant of Virginia type

Less prone to oxidation than its conventional counterpart, high-oleic peanut (Arachis hypogaea L.) containing ≥ 72% oleate and < 8% linoleate is preferred by processors, seed sellers and consumers. Development of high-oleic peanut cultivars with suitable pod/seed size and shape may satisfy the need from food processors manufacturing whole kernel or halve products. In this study, a high-oleic Virginia type peanut mutant was identified through screening of a 15 mmol/L sodium azide mutagenized M3 population with near infrared spectroscopy. Sequencing of the mutated and wild type FAD2A/FAD2B genes detected 2 point mutations. The G448A mutation in FAD2A was the same as in previous reports, causing an amino acid change of D150N. G558A in FAD2B was a novel mutation, resulting in a stop codon and premature termination of protein synthesis. 16 promising lines with acceptable productivity and pod/seed characters have been tentatively bred, which will be evaluated further in yield tests with replications after seed increase.

Nutritional and bioactive composition of Spanish, Valencia, and Virginia type peanut skins

The aims of this study were to determine the proximate and amino acid compositions, mineral content, and fatty acid and proanthocyanidins (PAC) profiles of peanut skins (PS) from three varieties of peanuts. Proximate composition showed that PS had a moisture content from 9.71 to 11.0%, ash content from 2.07 to 2.13%, fat content from 9.59 to 10.2%, protein content from 8.88 to 12.7%, and dietary fiber from 38.8 to 42.8%. The amino acid composition indicated that lysine and phenylalanine, glycine, and glutamine were the predominant amino acids in PS. Mineral content indicated that potassium was the main macro-element in PS. Palmitic, oleic, and linoleic acids were the predominant fatty acids in PS. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of PAC showed that the predominant masses were typical of (epi)catechin monomers with “A-type” interflavan bonds. Deconvolution of overlapping isotope patterns observed with MALDI-TOF MS indicates that in all PS, 95 % of the PAC oligomers contain one or more A-type bonds. These results indicate that PS may be used as functional ingredients to improve profitability of the peanut industries through the use of a low-value by-product. To the best of our knowledge, this is the first study providing a chemical evaluation and comparison of PS from three varieties of peanuts.

Peanut Response to Seeding Density and Digging Date in the Virginia-Carolina Region

ABSTRACT Large-seeded virginia market type peanut (Arachis hypogaea L.) cultivars are common in Virginia and North Carolina, but cost more to plant than runner market type peanut cultivars when the goal is to establish the same plant population. Decreasing seeding density could help growers to reduce production costs, as long as thinner stands do not negatively impact yield and economic return. Selecting the optimum digging time is a decision that could significantly influence growers' production and economics. Field experiments were conducted in Virginia and North Carolina at four site-year environments in 2016 and 2017 to examine the influence of seeding density (109, 143, 180, and 200 thousand seeds/ha) and digging date (130, 140, and 150 days after planting [DAP]) on virginia type peanut cultivar (Bailey, Sullivan, Wynne) performance. Regardless of cultivar and digging date, the greatest pod yield (5930 kg/ha) was achieved from the 200 thousand seeds/ha density, but the 143 thousand seeds/ha density had the highest economic return ($2990/ha). At three of the four site-years, the 140 DAP digging date, i.e. 1400 to 1600 C growing degree days (GDD), produced the greatest pod yield (5470 kg/ha) and had the highest economic return ($2750/ha). While individual site-years should be monitored for digging date, growers should be prepared to dig the currently available cultivars from 1400 to no more than 1600 C accumulated GDD.

High oleic peanuts improve parameters leading to fatty liver development and change the microbiota in mice intestine.

BackgroundOleic-acid consumption can possibly prevent or delay metabolic diseases. In Israel, a Virginia-type peanut cultivar with a high content of oleic acid has been developed.ObjectiveThis study examined the effect of consuming high oleic peanuts (D7) on the development of fatty liver compared to the standard HN strain.DesignThe two peanut cultivars were added to normal diet (ND) and high-fat (HF) mouse diet. Male C57BL/6 mice were fed for 8 and 10 weeks on a 4% D7, 4% HN, or control diet. At the end of the experiments, blood and tissues were collected. Triglyceride, lipid levels, histology, and protein expression were examined. The diets’ effects on intestinal microbiota were also evaluated.ResultsBoth D7 and HFD7 led to a reduction in plasma triglycerides. Lipids, triglycerides, and free fatty acids in the liver were low in diets containing D7. Additionally, CD36 expression decreased in the D7 group. Consumption of D7 led to higher Prevotella levels, and consumption of ND that contained HN or D7 led to a lower Firmicutes/Bacteroidetes ratio.ConclusionThese findings suggest that consumption of peanuts high in oleic acid (D7) may have the potential to delay primary fatty liver symptoms.

Nitrogen-fixation drought tolerance in virginia-type peanut

ABSTRACTSymbiotic nitrogen-fixation activity of grain legumes commonly does not exhibit tolerance to soil drying, including in peanut (Arachis hypogaea L.). Since the demand for nitrogen of peanut is large in the synthesis of seeds with high protein concentration, loss of nitrogen-fixation activity can result in major yield decreases. The objective of this study was to search the germplasm of virginia-type peanut for sources of nitrogen-fixation drought tolerance. The first phase was a field screen in one growing season of 100 lines from which leaves were harvested and nitrogen concentration measured. Research in soybean had shown that low leaf-nitrogen concentration was associated with nitrogen-fixation drought tolerance. A wide range of leaf nitrogen concentrations was observed, and 10 lines of low leaf nitrogen (23.1 to 26.4 mg N g−1) were identified for the second phase of study. The second phase of study was done in a greenhouse with 5-week old plants sealed in pots subjected to a 2-week dry down. Each day, the plants were briefly exposed to acetylene to measure acetylene reduction activity as an indicator of nitrogen-fixation activity. The soil water content, at which a decline in nitrogen fixation was initiated, was not different among seven lines. Three of the lines exhibited high sensitivity of nitrogen fixation to soil drying. None of the lines, however, exhibited substantial tolerance of nitrogen fixation to soil drying, indicating a need to search an even more diverse population of peanut to identify a genetic source for tolerance.

Making Crops Climate Ready

Making Crops Climate Ready

Metabolite Profiles of Raw Peanut Seeds Reveal Differences between Market‐Types

Peanuts (Arachis hypogaea L.) are prized for their flavor and popular worldwide as food or as food ingredients. The raw peanut seed contains the precursor compounds to roasted peanut flavor and has the potential to be manipulated through traditional breeding methods. However, little is known about the metabolome of the raw seeds. Comprehensive metabolite profiles of both raw runner and Virginia-type peanuts were determined. Using a system incorporating several methodologies including (RP)/UPLC-MS/MS and HILIC/UPLC-MS/MS, along with quantitation of fatty acids, free amino acids, and tocopherols, 365 metabolites were identified and of these, 52 were significantly different between market types (P<0.05). Higher levels of gamma-glutamylalanine, oxylipins, purine metabolites, and alpha-ketoglutarate derived members of the glutamate family of amino acids defined the Virginia-type, while runner-type peanuts were differentiated by their ethylmalonate and eicosenoate content. This study presents a comprehensive analysis of the raw peanut seed, providing knowledge of the range of small molecules present in peanuts. The new information presented here will enable future research for peanut quality improvement. PRACTICAL APPLICATION: Peanuts are widely used as snack foods and as food ingredients. Knowledge of the secondary metabolite compounds in raw peanuts is needed to determine their importance in peanut flavor and nutritional quality. This report used a nontargeted analytical approach for the identification of these types of compounds in peanuts for the first time. These data were supplemented with quantitative analysis of free amino acids and tocopherols and discussed as potential flavor precursors and health promoting compounds.

Prevalence and Concentration of Salmonella on Raw, Shelled Peanuts in the United States

Recalls and outbreaks associated with Salmonella contamination in peanut-containing products have been reported over the past several years. Very limited data existed on the prevalence and concentration of Salmonella on raw, shelled peanuts in the United States. An initial study was completed in 2012 to estimate the prevalence and concentration of Salmonella on Runner- and Virginia-type raw, shelled peanuts in the United States from the 2008 through 2011 crop years, which were proportionately sampled from each growing region based on 2007 production volume. That study was extended to include samples of Runner- and Virginia-type peanuts from 2013, 2014, and 2015 crop years proportionately sampled from each growing region on the basis of the 2008 through 2010 volumes. Of the total 2,506 raw, shelled peanut samples, 41 (1.63%) were positive for Salmonella by the VIDAS SLM assay. Salmonella serovars identified in this study included Agona, Anatum, Bardo, Braenderup, Cannstatt, Dessau, Gaminara, Litchfield, Hartford, Inverness, Mbandaka, Meleagridis, Muenchen, Newport, Pakistan, Rodepoort, Rubislaw, Tennessee, and Tornow. The concentration levels of Salmonella in positive samples, as determined by most probable number (MPN), ranged from <0.003 to 2.4 MPN/g. These data will be useful when designing and validating processes for the reduction or elimination of Salmonella in peanuts or peanut-containing products or both.

Genetic insight and mapping of the pod constriction trait in Virginia-type peanut

BackgroundPod constriction is an important descriptive and agronomic trait of peanut. For the in-shell Virginia marketing-type, this trait has commercial importance as well, since deeply constricted pods have a tendency to break, which makes them unmarketable. Classical genetic studies have indicated that pod constriction in peanut is controlled by one to four genes, depending on the genetic background. In all of those studies, pod constriction was evaluated visually as opposed to quantitatively. Here, we examined the genetic nature of this trait in the Virginia-type background. Our study involved 195 recombinant inbred lines (F7RILs) derived from two closely related cultivars that differ in their degree of pod constriction. Pod constriction was evaluated visually and quantitatively in terms of the pod constriction index (PCI), calculated as the average ratio between the pod’s waist and shoulders.ResultsANOVA and genetic parameters for PCI among the F7RILs in three blocks showed very significant genotypic effect (p(F) < 0.0001) and high heritability and genetic gain estimates (0.84 and 0.52, respectively). The mean PCI values of the different RILs had a bimodal distribution with an approximate 1:1 ratio between the two curves. Pod constriction was also determined visually (VPC) by grading the degree of each RIL as ‘deep’ or ‘slight’. The χ2 test was found to not be significantly different from a 1:1 ratio (p = 0.79) as well. SNP-array-based technology was used to map this trait in the RIL population. A major locus for the pod constriction trait was found on chromosome B7, between B07_120,287,958 and B07_120,699,791, and the best-linked SNP explained 32% of the total variation within that region. Some discrepancy was found between the SNPs original location and the genetic mapping of the trait.ConclusionThe trait distribution and mapping, together with data from F1 and F2 generations indicate that in this background the pod constriction is controlled by a major recessive gene. The identity of loci controlling the pod constriction trait will allow breeders to apply marker-assisted breeding approaches to shift allelic frequencies towards a slighter pod constriction and will facilitate future effort for map-based gene cloning.

Purification and Characterization of Naturally Occurring Post-Translationally Cleaved Ara h 6, an Allergen That Contributes Substantially to the Allergenic Potency of Peanut

The 2S albumin Ara h 6 is one of the most important peanut allergens. A post-translationally cleaved Ara h 6 (pAra h 6) was purified from Virginia type peanuts, and the cleavage site was mapped using high-resolution mass spectrometry. Compared to intact Ara h 6, pAra h 6 lacks a 5-amino acid stretch, resembling amino acids 43-47 (UniProt accession number Q647G9) in the nonstructured loop. Consequently, pAra h 6 consists of two chains: an N-terminal chain of approximately 5 kDa and a C-terminal chain of approximately 9 kDa, held together by disulfide bonds. Intermediate post-translationally cleaved products, in which this stretch is cleaved yet still attached to one of the subunits, are also present. The secondary structure and immunoglobulin E (IgE) binding of pAra h 6 resembles that of intact Ara h 6, indicating that the loss of the nonstructured loop is not critical for maintaining the protein structure. Commercially available monoclonal and polyclonal immunoglobulin G (IgG) antibodies directed to Ara h 6 react with both intact Ara h 6 and pAra h 6, suggesting that the involved epitopes are not located in the area that is post-translationally cleaved. No differences between intact Ara h 6 and pAra h 6 in terms of IgE binding were found, suggesting that the area that is post-translationally cleaved is not involved in IgE epitopes either. For all main cultivars Runner, Virginia, Valencia, and Spanish, intact Ara h 6 and pAra h 6 occur in peanut at similar levels, indicating that pAra h 6 is a consistent and important contributor to the allergenic potency of peanut.

Genotype-by-environment effects on the performance of recombinant inbred lines of Virginia-type peanut

Peanut (Arachis hypogaea L.) is known to be sensitive to genotype-by-environment interaction (GEI) effects. While previous studies have reported strong GEI effects on peanut yield, most of those studies involved a relatively small number of unrelated genotypes. We examined the extent of GEI effects in elite Virginia-type peanut using a large population of recombinant inbreed lines (RILs). Two-hundred-sixty-six F7 RILs derived from different cultivars were grown in three environments. Net pod yield (NPY) was evaluated along with 11 other traits. ANOVA revealed that genotype and environment affected all of the examined traits, except for the triplet trait. The substantial influence of the environment was also demonstrated in a genetic-parameter analysis, in which the phenotypic variation coefficients were almost double those for genotypic variation. Still, relatively high heritability and genetic gain values were found for pod weight and NPY. Since NPY is the main target for selection, it was analyzed further. Path analysis showed that NPY is most directly influenced by pod weight and the shelling ratio. A significant GEI effect on NPY was identified using an AMMI model that described 42.7% of the total variation. This GEI component was subjected to a principal components analysis, which confirmed that the variability due to the different environments was greater than the variability that could be attributed to the different genotypes. Yet, several lines had stable yields across environments. These results demonstrate the importance of multi-location phenotyping for QTL analyses and crop improvement in peanut.

RETRACTED: Simulating peanut (Arachis hypogaea L.) growth and yield with the use of the Simple Simulation Model (SSM)

Abstract The use of crop simulation models for interpreting experiments and analyzing production systems in different management and environmental conditions is common in the literature. In this study, parameterization and evaluation of the Simple Simulation Model (SSM) for the prediction of peanut ( Arachis hypogaea L.) growth and yield was conducted for the first time. Data from different field experiments from Astaneh Ashrafieh of northern Iran were used for coefficient estimation and model evaluation for the Virginia-type peanut variety North Carolina 2 (cv. NC2). After estimation of genetic parameters, the model was tested using independent data. The SSM simulated peanut growth and yield with reasonable accuracy, using data of more than 10 field experiments from different environmental conditions (11 experiments in the parameterization stage and 15 experiments in the evaluation stage). Based on data of independent experiments that were not used for parameterization, the model predicted an acceptable percentage of the observed results concerning days to harvest maturity (r = 0.46, CV = 5%), accumulated dry matter (r = 0.66, CV = 15%), grain yield (r = 0.55, CV = 21%), and pod yield (r = 0.45, CV = 18%). Local sensitivity analysis with 23 parameters indicated that two parameters related to leaf development and a parameter related to yield formation were the most sensitive cultivar-specific parameters; thus, estimation of the parameters need to be done with care for new cultivars. The SSM provided an adequate level of peanut growth simulation and based both on its transparency and easiness-to-use can be used as a valid tool for simulating growth of peanut Virginia-type varieties.

Transgressive Segregation and Long-Term Consistency for High TSWV Field Resistance in the ‘Georgia-06G’ Peanut Cultivar

Tomato spotted wilt disease caused by tomato spotted wilt virus (TSWV) is a major peanut (Arachis hypogaea L.) production problem in the United States. TSWV has become endemic since the mid-1980s in the southeastern U.S. peanut production area. ‘Georgia-06G’ is a large-seeded, TSWV-resistant, runner-type peanut cultivar, whereas ‘Georgia Greener’ is a sister line with a smaller seed size than Georgia-06G. Both Georgia-06G and Georgia Greener have greater TSWV general field resistance with higher yields, total sound mature kernels grade, and dollar values than the parents (‘Georgia Green’ and ‘C-99R’), which shows transgressive segregation for these desirable quantitative traits. Therefore, the objective of this 12-year study was to evaluate the higher TSWV host-plant resistance found in the Georgia-06G over time compared with many other runner- and virginia-type peanut cultivars and advanced breeding lines. Despite yearly variability in TSWV and total disease incidence, the data indicate that Georgia-06G exhibited long-term high TSWV and total disease field resistance at midseason and late season, respectively. Georgia-06G was also found to have among the highest pod yield and dollar value every year. The higher general TSWV field resistance of Georgia-06G appears to be consistent across many years and locations, similar to the moderate TSWV resistance in Georgia Green.