Virginia-type Peanut Research Articles

Registration of ‘Bailey’ Peanut

‘Bailey’ (Reg. No. CV‐111, PI 659502) is a large‐seeded virginia‐type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) with partial resistance to five diseases that occur commonly in the Virginia‐Carolina production area: early leaf spot (caused by Cercospora arachidicola Hori), late leaf spot [caused by Cercosporidium personatum (Berk. & M.A. Curtis) Deighton], Cylindrocladium black rot [caused by Cylindrocladium parasiticum Crous, M.J. Wingf. & Alfenas], Sclerotinia blight (caused by Sclerotinia minor Jagger), and tomato spotted wilt (caused by Tomato spotted wilt tospovirus). It also has partial resistance to southern stem rot (caused by Sclerotium rolfsii Sacc.). Bailey was developed as part of a program of selection for multiple‐disease resistance funded by growers, seedsmen, shellers, and processors. Bailey was tested under the experimental designation N03081T and was released by the North Carolina Agricultural Research Service (NCARS) in 2008. Bailey was tested by the NCARS, the Virginia Agricultural Experimental Station, and five other state agricultural experiment stations and the USDA‐ARS units participating in the Uniform Peanut Performance Tests. Bailey has an alternate branching pattern, an intermediate runner growth habit, medium green foliage, and high contents of fancy pods and medium virginia‐type seeds. It has approximately 34% jumbo and 46% fancy pods, seeds with tan testas and an average weight of 823 mg seed−1, and an extra large kernel content of approximately 42%. Bailey is named in honor of the late Dr. Jack E. Bailey, formerly the peanut breeding project's collaborating plant pathologist.

Commercial Peanut (Arachis hypogaea L.) Cultivars in the United States: Phytosterol Composition

Phytosterols in commercially grown Runner, Virginia, and Spanish peanuts (n = 221) from 2005 and 2006 were quantified by a combination of acid hydrolysis and alkaline saponification steps followed by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry analysis of the trimethylsilyl derivatives. Δ(5)-Avenasterol, which partially degrades during acid hydrolysis, was quantified after alkaline saponification plus direct analysis of the steryl glucosides isolated by solid-phase extraction. β-Sitosterol, Δ(5)-avenasterol, campesterol, and stigmasterol were identified in peanut lipid extracts as the dominant sterols by retention time mapping and mass spectra with recoveries ∼99%. Clerosterol, Δ(5,24(25))-stigmastadienol, Δ(7)-sitosterol + cycloartenol, and one unidentified sterol were also present but at low levels. Free and esterified phytosterols accounted for ∼80% of the total sterols determined; the remainder was attributed to steryl glucosides. The total sterol level in Spanish market type peanuts (144.1 ± 5.3 mg/100 g) was significantly greater than both Runners (127.5 ± 6.3 mg/100 g) and Virginias (129.3 ± 6.9 mg/100 g) (P < 0.05). Tamspan 90 (146.9 mg/100 g) followed by OLIN (138.5 mg/100 g) showed the highest total sterol content among the cultivars examined. Cultivar effects were strongly significant (P < 0.001) for all phytosterols, whereas production year effects were strongly significant (P < 0.001) for Δ(5)-avenasterol, Δ(5,24(25))-stigmastadienol, and the combined quantities of Δ(7)-sitosterol + cycloartenol, which coeluted. Cultivar × year interactions were strongly significant (P < 0.001) in all sterols except for Δ(7)-sitosterol + cycloartenol (P < 0.01). Total phytosterol contents were markedly higher than those reported in the existing literature for Runner and Virginia type peanuts, partially attributed to the inclusion of steryl glucosides in the analysis.

Application of NIR Reflectance Spectroscopy on Determination of Moisture Content of In-Shell Peanuts: A Non-Destructive Analysis

NIR spectroscopy was used to measure the moisture content (MC) of Virginia and Valencia type in-shell peanuts. Peanuts were conditioned to various moisture levels between 7% and 26% (wet basis), and the MC was verified using the standard oven method. Sample from the various moisture levels were separated into two groups, as calibration and validation. NIR absorption spectral data from 400 nm to 2500 nm were collected using peanuts within the calibration and validation sample sets. Measurements were obtained on 30 replicates within each moisture level. Partial least squares (PLS) analysis was performed on the calibration set, and models were developed using the raw spectral data and its derivative function data. The standard error of calibration (SEC) and R2 of the calibration models were calculated to select the best calibration model for each peanut market type. Both Valencia and Virginia types gave an R2 value of 0.99 for the derivative spectral data treatment as well as for the raw data. The selected models were used to predict the moisture content of peanuts in the validation sample set. Predicted and reference moisture contents were compared. Relative percent deviation (RPD) and standard error of prediction (SEP) were calculated to validate the goodness of fit of the prediction model. The raw reflectance spectra model gave an RPD of 5.55 with a corresponding SEP of 0.97 for Valencia type peanuts, which is an indicator that the model is good for quality control and analysis. For Virginia type peanuts, the derivative reflectance spectra model gave the highest RPD value of 5.75 and the lowest SEP of 0.771. Thus, these two models were selected for the respective peanut types as the best models for prediction of moisture content.

Identification of Suitable Internal Control Genes for Quantitative Real-Time PCR Expression Analyses in Peanut (Arachis hypogaea)

Abstract Real-time qPCR is currently the most sensitive technique available for the detection of low-level mRNA expression. For more reliable and precise gene expression analyses, real-time PCR data for a sequence of interest must be normalized against that of a control gene, which is uniformly expressed in various tissues and during different phases of development. So far, suitable internal controls for gene expression studies in peanut have not been identified. We assessed the expression of 10 frequently used housekeeping genes, specifically ubq10, gapdh, hel1, yls8, 14-3-3, 60s, ubc, ef-1α, act7, and adh3. Using the algorithms available through the GeNorm and NormFinder programs, the stability of their expression was estimated in a set of five diverse peanut tissue samples derived from a Virginia-type peanut cultivar (Shulamit). Collectively, the gene with the most stable expression across all of the examined tissues and both programs was adh3, followed by 60s and yls8, which had minimal estimated intra- and inter-tissue variation. The stability of two stable reference genes (adh3 and yls8) compared with two less stable (14-3-3 and ubq10) reference genes was validated in unpooled tissue samples from five peanut kernel developmental stages. Finally, the effect of the use of one or more reference genes on the observed relative expression levels of an important seed oil metabolism gene, diacylglycerol acyltransferase 1 (Dgat1), during kernel development was demonstrated. Based on findings, the suggestion is that adh3, or a combination of this gene with 60s and yls8 should be considered for use in quantitative mRNA expression analyses in Arachis, particularly in studies involving seed development; whereas ubq10 and gapdh should be avoided.

Field Evaluation of Virginia-Type Peanut Cultivars for Resistance to Tomato Spotted Wilt Virus, Late Leaf Spot, and Stem Rot

Abstract Susceptibility to viral and fungal diseases is a major factor limiting profit in the production of virginia-type peanuts (Arachis hypogaea L.) in the South Carolina coastal plain. Field tests were conducted over a three-year period (2006–08) to evaluate the disease resistance of 47 experimental virginia-type breeding lines and eight cultivars. Relative to commercially available standards, cultivar Bailey (recently released by N. C. State Univ.), three sister lines (N03088T, N03089T, and N03090T), and N03091T were found to have consistently less susceptibility to tomato spotted wilt tospovirus; late leaf spot, Cercosporidium personatum (Berk. and Curt.) Deighton; and stem rot, Sclerotium rolfsii Sacc. The level of field resistance measured for these three diseases was comparable to that of a resistant runner-type cultivar, Georgia-03L. Yield was highly correlated with multiple disease resistance, and yield performance of some resistant lines exceeded the best commercial standard cultivars under reduced fungicide programs. Potential negative attributes of Bailey, its sister lines, and N03091T were a greater susceptibility to leafhopper injury, Empoasca fabae (Harris), and a relatively larger plant size at maturity, without well defined rows to facilitate digging. Other lines that demonstrated reduced susceptibility to both tomato spotted wilt and stem rot were N03005J and N02009. Although only evaluated in the last test year, five Univ. of Florida lines (FLMR7, FLMR9, FLMR12, FLMR14, and FLMR15) and Georgia-08V (recently released by the Univ. of Georgia) also showed some reduction in stem rot susceptibility relative to the standard (cultivar NC-V 11). Equally important, many experimental lines were identified with significantly greater disease susceptibility than current commercial cultivars. Under South Carolina production conditions, these lines would be poor candidates for advancement. Deployment of the multiple disease resistance found in these experimental cultivars offers several potential benefits beyond direct yield improvement: reduction of fungicide input costs for both foliar and soil disease control, prolonging the utility of currently available fungicides, and reduction of weather related harvest risk by allowing earlier initial planting dates.

Calcium Nutrition of Peanut Grown in Solution Culture. I. Genetic Variation in Ca Requirements for Vegetative Growth

ABSTRACT Calcium (Ca) deficiency is an important problem in peanut (Arachis hypogaea L.) production, with lines from the sub-species A. hypogaea hypogaea (Virginia type) being considered more susceptible to Ca deficiency than those of A. hypogaea fastigata (Spanish and Valencia types). Fifteen peanut lines comprising five Virginia bunch, one Virginia runner, six Spanish, two Valencia types, and one Valencia × Spanish cross were grown for 30 d in continuously flowing solution culture at constant external Ca concentrations ranging from 9 to 2500 μM. Two lines required <9 μM Ca for near-maximum growth, whereas 5 lines required 15–20 μM, six lines required 25–50 μM, and two lines required >75 μM Ca for maximum growth. The Ca concentration in the youngest fully expanded leaves required for maximum growth also differed considerably among the lines, ranging from <5.7 g kg−1 in ‘SH-2’ to 17.3 g kg−1 in ‘Red Spanish’). The differences in solution and tissue Ca requirement for growth did not coincide with the broad botanical groupings despite that Virginia type peanut lines had consistently lower Ca concentrations in youngest fully expanded leaves than Spanish or Valencia lines at all solution Ca concentrations. Leaf magnesium (Mg), potassium (K), phosphorus (P), iron (Fe), and manganese (Mn) concentrations in the leaves decreased as the solution Ca concentration increased and it seemed probable that growth reductions observed at above-optimum Ca concentrations were due to induced deficiencies of P, Mg, or possibly Fe.

Comparison of Virginia-Type Peanut Cultivars and Interspecific Hybrid Derived Breeding Lines for Leaf Spot Resistance, Yield, and Grade

AbstractDisease resistant cultivars with good quality are needed by U.S. peanut growers to lower production costs. In the Virginia-Carolina (V-C) production area, use of resistant cultivars to reduce leaf spots would be a cost-effective and environmentally safe alternative to chemical applications. Twenty-six interspecific hybrid derived breeding lines with 5 Arachis species in their pedigrees, six resistant A. hypogaea checks and 11 susceptible cultivars were evaluated for leaf spot resistance in field tests at the Peanut Belt Research Station in Lewiston, NC from 2004 to 2006 without leaf spot fungicides. Defoliation was rated on a 1–9 proportional scale with 1 = no defoliation (resistant) and a 9 = complete defoliation (susceptible). The mean defoliation score of the cultivars was 6.8±0.1 (range = 6.4 to 7.4), compared to 5.3±0.1 (range = 4.4 to 6.3) for the interspecific hybrid derived breeding lines. Some of the interspecific hybrid derived breeding lines showed levels of leaf spot resistance similar to the resistant A. hypogaea checks (mean = 4.3±0.2), suggesting that these breeding lines contain genes conditioning resistance to the leaf spots. The combined mean yield of the cultivars was 2709±103 kg/ha (range = 2296 kg/ha to 3070 kg/ha), whereas that of the interspecific hybrid derived breeding lines was 3169±119 kg/ha (range = 2467 kg/ha to 3767 kg/ha). Evaluation of selected grade characteristics showed that several interspecific hybrid derived breeding lines have grade similar to those of the commercial cultivars. Sixteen of the 26 interspecific hybrid derived breeding lines with five different diploid species in their pedigrees and NC 7, the commercial flavor standard for the V-C area, were also evaluated for sensory quality. No significant variation among test entries was found for the roasted peanut, sweet, or bitter sensory attributes. This suggests that high levels of leaf spot resistance can be combined with superior yield, grade and other quality factors and that some of these lines may become useful for commercial production in the V-C area.

Effect of silver nitrate on multiple shoot formation of Virginia-type peanut through shoot tip culture

A protocol for micropropagation of Virginia-type peanut plants, an ancient crop of the New World, is reported. This study was conducted to explore the effect of silver nitrate (AgNO3), alone or in combination with growth regulators, on multiple shoot formation from shoot tip culture. Incorporation of AgNO3 into the medium, without growth regulators, induced regeneration of the explants (which did not develop at all in the AgNO3-free medium), and stimulated the emergence of axillary shoots. When AgNO3 was added in combination with cytokinins and α-naphthaleneacetic acid (NAA), maximum average shoot number per regenerating explant was recorded (6.3) in Murashige and Skoog (MS) medium containing 33 μM 6-benzyladenine, 5.3 μM NAA, and 23.54 μM AgNO3. Moreover, AgNO3 showed a positive and marked effect on both shoot elongation and the reduction of callus proliferation from the basal ends of shoot tips. Following a period of elongation, the shoots were rooted in hormone-free Ms medium, showing no residual effects due to the long-term culture in AgNO3-containing media. Acclimatization was easily obtained after plantlets were transferred to pots under greenhouse conditions, with 90% survival.

Response of Four Virginia-Type Peanut Cultivars to Prohexadione Calcium as Affected by Cultivar and Planting Pattern

Abstract An experiment at Suffolk, VA in 2001 and 2002 evaluated the response of virginia-type peanut (Arachis hypogaea L.) to the growth regulator prohexadione calcium as affected by cultivar and ...

Improving Shelf Life of Roasted and Salted Inshell Peanuts Using High Oleic Fatty Acid Chemistry

Abstract Major markets for the large-seeded virginia-type peanut (Arachis hypogaea L.) include roasted inshell and salted inshell products with short shelf life being a common consumer complaint. Unlike many other peanut products, it is not economically possible to package these inshell peanuts in nitrogen flushed, oxygen barrier bags. A number of studies have shown that roasted runner-type peanuts with high contents of oleic fatty acid have improved oxidative stability and longer shelf life. A large-seeded, virginia-type peanut cultivar (AgraTech VC-2) with the high oleic trait has been released but no information is available on its shelf life stability. Therefore, this high oleic cultivar and the normal oleic cultivar VA 98R from the 2000 and 2001 crop were used for shelf life evaluations. Peanuts were sized into the fancy inshell grade for roasted inshell and salted inshell products. Peroxide value (PV) results for the roasted inshell peanuts indicated that normal oleic fatty acid (50% range) peanuts reached a PV of 20 meq/kg by the end of 4 wk of storage. On the other hand, the high oleic fatty acid (80% range) peanuts did not reach a value of 20 meq/kg until approximately 32 wk. When salted inshell the normal oleic peanuts exceed a PV of 20 meq/kg before the 2nd wk, whereas the high oleic peanuts still had not reached a PV of 20 meq/kg after 40 wk of storage. These results show a significant advantage of high oleic peanuts for extending shelf life of large-seeded, virginia-type peanuts for either roasted or salted inshell processing.

Selection of alternative genetic sources of large-seed size in Virginia-type peanut: evaluation of sensory, composition, and agronomic characteristics.

Jenkins Jumbo, the ancestral source of large-seed size in the Virginia market type (Arachis hypogaea L.), has been shown to have a deleterious effect on flavor of peanut. The pervasiveness of Jenkins Jumbo in the ancestry of large-seeded germplasm contributes to the generally less intense roasted peanut flavor of U.S. cultivars of the Virginia market type. As a remedy to this problem, alternative sources of large-seed size were sought. Nine large-seeded selections, with NC 7 and Florunner as checks, were tested in replicated trials in North Carolina and Florida from 1996 to 1998. Pod yield, grade, weight of 100 seeds, and oil, sugar, and starch contents were measured. A descriptive sensory panel evaluated flavor attributes of a roasted sound mature kernel (SMK) sample from each plot. NC 7 scored low for sweet sensory attribute, high for bitter, and median for roasted peanut. UF714021, a multiline incorporating the Altika cultivar with several sister lines, had the best flavor profile of the large-seeded selections, but it did not have particularly large seeds relative to NC 7. The largest seeded selections were X90037 and X90053, both derived from Japan Jumbo. Flavor scores for X90037 were similar to those for NC 7 for roasted peanut (3.0 vs 2.9 flavor intensity units, fiu) and sweet (2.7 vs 2.6 fiu) but worse than NC 7 for bitter (3.3 vs 3.7 fiu) and astringent (3.5 vs 3.7 fiu). X90053 had intermediate values for roasted peanut and astringent, high value for sweet, and low for bitter. Other lines that had or were likely to have Jenkins Jumbo as a recent ancestor were generally poor in roasted flavor, supporting the hypothesis that ancestry from Jenkins Jumbo imparts poor flavor characteristics. With the exception of the unexpected relationship between astringent attribute and extra large kernel (ELK) content (r = 0.82, P < 0.01), there were no significant correlations between sensory attributes and the important agronomic traits: yield, meat, and ELK content. Among the nine large-seeded lines tested in this study, three appear to have greater potential for use as parents: 86x45B-10-1-2-2-b2-B, UF714021, and X90053.

Tolerance of Virginia-Type Peanut to Different Application Timings of 2,4-DB

Abstract Field studies were conducted to determine the effects of 2,4-DB application timings on yield and market quality of virginia-type peanut. Trials were conducted at three locations in Texas and one location in North Carolina in 1997, 1998, and 1999. 2,4-DB at 0.45 kg ae/ha was applied 30, 45, 60, 90, and 120 d after planting (DAP). Additional timings included combinations of 30 DAP followed by (fb) 60, 90, or 120 DAP; 60 DAP fb 90 or 120 DAP; and 90 DAP fb 120 DAP. Peanut yield, market grade factors, and pod and seed weight were not influenced by various application timings of 2,4-DB.

Incidence of Tomato spotted wilt virus (Bunyaviridae) and Tobacco Thrips in Virginia-Type Peanuts in North Carolina.

Virginia-type peanut (Arachis hypogaea) cultivars were monitored for incidence of Tomato spotted wilt virus (TSWV) and abundance of Frankliniella fusca, the tobacco thrips, in North Carolina during 1995 and 1996. A preliminary evaluation of 225 peanut genotypes for TSWV-resistant or -tolerant genotypes was conducted in 1995. The incidence of TSWV in cultivar NC-9 was twice that of cultivar NC-V11. In 1996, field trials designed to evaluate TSWV susceptibility were conducted with three widely grown commercial peanut cultivars in North Carolina. They were NC-9, NC-V11, and NC-12C, a newly released cultivar. A randomized complete block design was utilized at three locations. Disease incidence was evaluated weekly from 2 weeks postplanting until 2 weeks prior to harvest. Mechanical inoculation of the three cultivars resulted in no difference in relative leaf virus titer as determined from optical density readings following DAS-ELISA for 4 successive weeks beginning at 13 days postinoculation. NC-9 ranked highest in incidence of disease (7%), followed by NC-12C (6%) and NC-V11 (5%). Thrips counts were greatest on NC-V11, followed by NC-9 and NC-12C. Disease incidence overall was 5.96%, but ranged from 3.08 to 11.15% among the three sites. Yield was affected by the temporal occurrence of symptoms beginning at the fifth week postplanting. Greatest yield losses occurred in those plants with the earliest visible foliar symptoms.

Yield of Peanut Genotypes Resistant to Root-Knot Nematodes1

Abstract Yields of six runner-, two spanish-, and one virginia-type breeding lines of peanut with resistance to the root-knot nematode, Meloidogyne arenaria, were compared to yields of susceptible cultivars in nematode-infested and noninfested field plots in 1996. Pod yields of resistant runner-, virginia-, and one of the spanish-type breeding lines were 1.5 to 4 times greater (P = 0.05) than pod yields of the susceptible cultivars Florunner, NC-7, and Tamspan 90 in two nematode-infested fields. Final nematode population densities on most resistant breeding lines were lower (P = 0.05) than those on the susceptible cultivars. In the noninfested field, all but one runner- and the two spanish-type resistant breeding lines had pod yields that were not different from that of the susceptible cultivars. Yields of the resistant breeding lines ranged from 3890 to 5152 kg/ha in the noninfested field. In 1997, yields of three of the runner-type breeding lines were compared to the yields of Florunner and Tamrun 96 in three fields not infested with M. arenaria. In one field, no differences were observed in pod yield among the breeding lines and cultivars; in the second field the yield of two of the breeding lines were not different from the susceptible cultivars; and in the third field, only TP259-3-5 had pod yield equivalent to that of the susceptible cultivars. These data indicate that resistant runner-type genotypes with high yield potential have been developed, but additional breeding efforts are needed to develop nematode resistance in high yielding spanish- and virginia-type peanuts.

Evaluation of Selected Foliar Applied Insecticides on Potato Leafhopper in Virginia-Type Peanut, 1997

Abstract Selected foliar applied insecticides were evaluated against PLH in Virginia-type peanut. ‘VA-C 92R’ peanut was planted on a producer’s farm in Isle of Wight County, VA using 36-inch row spacing. Foliar treatments were applied on 31 Jul as a full-coverage spray with a CO2-pressurized backpack sprayer calibrated to deliver 14.5 gpa at 50 psi through three D2-13 hollow-cone nozzles per row, one over the top and one on each side of each row. A RCB design was used with 4 replicates. Plots were 4 rows by 40 ft. PLH were sampled by making 5 sweeps per plot with a 15-cm-diameter sweep net and counting numbers of captured adults and nymphs. The pre-treatment sample was not taken on each plot, but was comprised of 20 random 5-sweep samples distributed throughout the planned test area. Data were analyzed using ANOVA and LSD procedures.

Response of Virginia-Type Peanut to Norflurazon

Abstract Four field experiments were conducted in North Carolina from 1994 to 1996 to determine the effect of norflurazon applied preemergence at 1.6 kg ai/ha to virginia-type peanut (Arachis hypogaea L.) cvs. NC 7, NC 9, NC 10C, NC-V 11, VA-C 92R, and AT VC-1. Injury 3 wk after planting was 7% or less in three experiments. Greater injury was noted on VA-C 92R relative to other cultivars in one of these experiments. Injury ranged from 25 to 41% in the fourth experiment, with greater injury noted on NC 9, NC-V 11, and VA-C 92R than on NC 7, NC 10C, or AT VC-1. Norflurazon did not affect peanut maturity, the percentage of extra large kernels, total sound mature kernels, or fancy pods. Norflurazon reduced peanut yield 6% irrespective of cultivars in two of four experiments.

Effects of Selected Foliar Applied Insecticides on Thrips Injury and Yield of Virginia-Type Peanut, 1997

Abstract Selected foliar applied insecticides were evaluated against TT injury and for effects on yield of Virginia-type peanut. ‘VA-C 92R’ peanut was planted 7 May at the Virginia Tech Tidewater Agric. Res. &amp; Ext. Ctr., Suffolk, VA using 36-inch row spacing. Eight gpa of metam-sodium 42% was injected into rows as a soil fumigant on 11 Apr, about 4 weeks prior to planting. Foliar sprays were applied on 23 May, after plants had emerged, and again 10 Jun. Sprays were applied in a 12- to 14-inch band over the row with a CO2-pressurized backpack sprayer calibrated to deliver 17.0 gpa at 22 psi through one 8003 E flat nozzle over the top of each row. A RCB design was used with 4 replicates. Plots were 4 rows by 40 ft. TT injury was evaluated based on a 0 to 10 scale where, 0 = no thrips induced plant injury, 1 = 10% injured leaves, 2 = 20% injured leaves, 3 = 30% injured leaves, 4 = 40% injured leaves, 5 = ≥ 50% injured leaves + ≤ 5% terminal buds injured, 6 = ≥ 50% injured leaves + 25% terminal buds injured, 7 = ≥ 50% injured leaves + 50% terminal buds injured, 8 = ≥ 50% injured leaves + 75% terminal buds injured, 9 = a≥ 50% injured leaves + ≥ 90% terminal buds injured, and 10 = dead plants. Yield was determined by digging, drying, and combining peanuts from the 2 center rows of each plot. Data were analyzed used ANOVA and LSD procedures.

Influence of Digging Date on Yield and Gross Return of Virginia-type Peanut Cultivars in North Carolina

Abstract Peanut (Arachis hypogaea L.) growers must balance complex interactions among cultivars, planting dates, environmental and physiological stresses during the growing season, and weather conditions at harvest when determining when to dig peanut. Ten field experiments were conducted in North Carolina from 1994 through 1996 to determine the influence of digging date on pod yield and gross return of virginia-type peanut. Beginning in mid- to late September, the cultivars NC 9, NC 10C, NCV-11, VA-C 92R, AgraTech (AT) VC-1, and NC 12C were dug on four dates approximately 7 d apart. Considerable variation in pod yield and gross return was noted among cultivars and experiments. Delaying digging increased pod yield and gross return in some but not all experiments. Greater variation in pod yield and gross return was observed for NC 10C than for AT VC-1 when compared across digging dates. Pod yield and gross return for NC9, NC V-11, VA-C 92R, and NC 12C were intermediate between NC 10C and AT VC-1. Of the cultivars evaluated, yield and gross return of AT VC-1 were the most stable over digging dates. These data suggest that growers should evaluate maturity of peanut in individual fields for each cultivar when determining when to dig. These data also suggest that factors other than maturity impact pod yield and gross return.

A Laboratory Colorimeter Method to Measure Pod Brightness in Virginia-Type Peanuts

Abstract Pod brightness is an important characteristic that influences consumers to purchase in-shell peanuts. A method is needed to quantitate pod brightness. Studies were conducted to determine whether pod color measurements were related to visual aesthetics rated by a panel representing seven virginia peanut shelling companies and to determine the effect of the optical aperture of the colorimeter on the measurements obtained. Forty-eight virginia-type pod lots were separated into fancy and jumbo fractions using a standard Federal-State Inspection Service grading peanut sizer. Pod color was measured for three subsamples of each fraction using a Hunterlab D25-PC2 colorimeter equipped with the D25-2RAL Reduced Area Viewing for L optical sensor (51-mm diameter sample area). The 96 samples also were rated by 11 Virginia-Carolina area shellers for pod color and size. Sheller ratings for the two traits were highly correlated (r &amp;gt; 0.6, P ≤ 0.01). Hunter L and b scores were strongly correlated with sheller color ratings. The colorimeter is a useful tool for measuring pod brightness as an adjunct to breeding for improved pod brightness. Use of a 95 mm aperture resulted in greater average Hunter L, a, and b scores and significantly reduced the variance among subsamples. The larger aperture should be used when the quantity of pods available for measurement permits.

Peanut Response to Prohexadione Calcium as Affected by Cultivar and Digging Date

Abstract An experiment at two locations in 1995 and two locations in 1996 evaluated virginia-type peanut (Arachis hypogaea L.) response to the growth regulator prohexadione calcium (calcium salt of 3,5-dioxo-4-propionylcyclohexanecarboxylic acid) as affected by cultivars and digging dates. Prohexadione calcium at 140 g ai/ha was applied at row closure and again 3 wk later in 1995 or 140 g/ha at row closure and 70 g/ha 3 and 6 wk later in 1996. The cultivars AgraTech (AT) VC-1, NC 9, NC 10C, NC 12C, NC-V11, and VA-C92R were dug on three separate dates approximately 11d apart. Response to prohexadione calcium was independent of digging dates. Prohexadione calcium altered canopy architecture and increased row visibility at harvest for all cultivars although the response was greatest with NC-V 11 and least with NC 9. Prohexadione calcium hastened pod maturity, increased percentages of extra large kernels, total sound mature kernels, and fancy pods, and increased peanut value/kg irrespective of cultivars and digging dates. Yield response to prohexadione calcium was cultivar dependent. NC 9 was most responsive, with yield increased 7 to 16% at all locations. Yields of ATVC-1, NC 10C, NC 12C, and NC-V 11 were increased 9 to 15% at two locations and unaffected at two locations. VA-C 92R was the least responsive, with yield increased 5% at two locations and decreased 8% at two locations.