Georgia Green Research Articles

Registration of ‘Georgia‐23RKN’ peanut

Registration of ‘Georgia‐23RKN’ peanut

Water-deficit stress induces prenylated stilbenoid production and affects biomass in peanut hairy roots: Exploring the role of stilbenoid prenyltransferase downregulation

The peanut plant is one of the most economically important crops around the world. Abiotic stress, such as drought, causes over five hundred million dollars in losses in peanut production per year. Peanuts are known to produce prenylated stilbenoids to counteract biotic stress. However, their role in abiotic stress tolerance has not been elucidated. To address this issue, hairy roots with the capacity to produce prenylated stilbenoids were established. An RNA-interference (RNAi) molecular construct targeting the stilbenoid-specific prenyltransferase AhR4DT-1 was designed and expressed via Agrobacterium rhizogenes-mediated transformation in hairy roots of peanut cultivar Georgia Green. Two transgenic hairy roots with the RNAi molecular construct were established, and the downregulation of AhR4DT-1 was validated using reverse transcriptase quantitative PCR. To determine the efficacy of the RNAi-approach in modifying the levels of prenylated stilbenoids, the hairy roots were co-treated with methyl jasmonate, hydrogen peroxide, cyclodextrin, and magnesium chloride to induce the production of stilbenoids and then the stilbenoids were analyzed in extracts of the culture medium. Highly reduced levels of prenylated stilbenoids were observed in the RNAi hairy roots. Furthermore, the hairy roots were evaluated in a polyethylene glycol (PEG) assay to assess the role of prenylated stilbenoids on water-deficit stress. Upon PEG treatment, stilbenoids were induced and secreted into the culture medium of RNAi and wild-type hairy roots. Additionally, the biomass of the RNAi hairy roots decreased by a higher amount as compared to the wild-type hairy roots suggesting that prenylated stilbenoids might play a role against water-deficit stress.

Bazı Yerfıstığı Çeşitlerinin Yağ Kalitesi Özellikleri ve Yağ Asidi Bileşimlerinin Belirlenmesi

The aim of this study was to determine the oil properties and fatty acid compositions of peanut cultivars (Arachis hypogaea L.) grown as the main crop in the Eastern Mediterranean transition zone of Turkey. The field experiment was conducted at the Oil Seed Research Institute experiment area in the main crop seasons of 2018 and 2019. The experiment was designed according to the randomized complete block design (RCBD) with three replications. Oil ratio, saturated fatty acids (palmitic acid, stearic acid), unsaturated fatty acids (oleic acid, linoleic acid), iodine value, and oleic/linoleic acid ratios were investigated in the experiment. Runner (Georgia Green), Spanish (Florispan), and Virginia market types (Sultan, Brantley, BATEM-Cihangir, BATEM-5025, Arioglu-2003, Halisbey, NC-7, Flower-22, Wilson, NC-V-11, Com, Osmaniye-2005, Gazipasa) varieties were used as plant materials. As a result of this study, NC-V-11 (52.23%) cultivar with the highest oil content was determined, followed by Florispan (52.16%), Brantley (52.10%), and Gerogia Green (51.54%). The lowest oil content was obtained from BATEM-Cihangir (44.57%) variety. Brantley variety was found to have the least palmitic acid ratio with 8.04%, while Florispan variety was found the highest with 12.24%. In terms of stearic acid ratios, the lowest value (1.38%) was determined in Com variety, while the highest value (2.91%) was found in Brantley variety. Brantley variety was found to have the highest oleic acid content (71.83%), which is one of the unsaturated fatty acids. Florispan variety had the lowest oleic acid content (43.70%). While Brantley variety had the lowest linoleic acid ratio (9.78%), it was determined that Com variety had the highest linoleic acid ratio (35.77%). The iodine value varied between 78.71-100.71, the lowest value was in Brantley and the highest value was in Com. The oleic acid/linoleic acid ratio was determined to vary between 1.22 and 7.35, the lowest value was in Florispan and the highest value was in Brantley. As a result of the research, it was determined that the variety with the highest oleic acid ratio in the Eastern Mediterranean Transition Zone was Brantley. Peanuts with high oleic acid content are preferred by producers and consumers because they have good quality and extend the shelf life of products producing with them.

Determination of macro and microelements in stem and leaf parts after harvest of some peanut varieties

This study was carried out to determine the post-harvest macro and micro element contents of some peanut cultivars grown under main crop conditions and to meet the nutritional requirements of the cultivars. The trial was carried out for two years (2015–2016) in the Alahanlı and Toprakkale trial areas of the Oil Seeds Research Institute. According to the results obtained from the experiment; In terms of macro elements, the highest phosphorus content was found in Batem Cihangir variety (0.122%), the highest potassium content was from Brantley (1,299%), the highest calcium content was from Osmaniye-2005 (2.396%), the highest magnesium content was NC-7 (0.851%) and the highest sodium content was obtained from NC V 11 (0.146%). In terms of micro-elements, the highest iron content was obtained from the varieties of Batem 5025, Arıoğlu-2003, Georgia Green, Batem Cihangir, the highest copper content was from the Brantley variety, the highest zinc content was from the Sultan variety, the highest manganese content was from the Batem Cihangir variety and the highest boron content was from the Flower-22 variety. There are limited studies on the nutritional elements of peanuts, and this study will be beneficial for the selection of the desired varieties for breeding, nutrient content, the use of fertilizers by the growers, and the improvement of the yield of the product.

Doğu Akdeniz geçit kuşağında farklı pazar tipi yerfıstıklarının (Arachis hypogaea L.) ikinci ürün yetitiriciliğinde bazı kalite ve özelliklerinin belirlenmesi

This study was carried out in Osmaniye location of Oil Seed Research Institute in 2020-2021 in order to determine some yield and quality characteristics in second crop cultivation of peanuts with different market types in the Eastern Mediterranean transition zone. Eleven different genotypes of Runner (Georgia Green) Virginia (NC 7, Masal, Halisbey, Wilson, Çom, Brantley, Sultan, Düziçi 1) Spanish (Florispan, Nigeria 1) types of peanut were used in the study. In the study, number of pods per plant, 1st quality pod ratio, pod weight per plant, 100 pod and seed weight, shelling percentage, pod yield, oil content and, protein content parameters were investigated. The number of pods per plant is between 20.8 (Nigeria 1) and 51.4 (Düziçi 1); pod weight per plant varied between between 12.3 g (Nigeria-1) and 64.9 g (Halisbey). It was determined that 100 pod weight and 100 seed weights varied between 66.8-289.0 g and 29.6-106.5 g, respectively. Pod yield varied between 1963 kg ha-1 (Nigeria 1) and 4846 kg ha-1 (Düziçi 1). As a result, it was determined that Düziçi 1 genotype, Brantley and Halisbey cultivars came to the fore in terms of the investigated characteristics in the Eastern Mediterranean Passage zone. In the study, while the second crop peanut variety suitable for the Eastern Mediterranean Transition zone was determined, the varieties to be used as breeding material were also determined.

Macro and Micro Element Composition of Some Peanut (Arachis hypogaea L.) Varieties in Turkey

This study was conducted to determine the macro and micro element contents of fourteen peanuts in Turkey. Virginia (NC-7, Halisbey, Arıoğlu-2003, Sultan Flower-22, Osmaniye-2005, Brantley, Wilson, Batem-5025, Batem-Cihangir, NC V 11 and Polen) Runner (Georgia Green) and Spanish (Florispan) market types have been evaluated. The research was conducted for two years (2015 to 2016) under main crop conditions in the trial areas of belonging to the Oil Seed Research Institute. The highest nitrogen content is from the Florispan (4.56%) variety, the highest phosphorus and sodium content is from the Halisbey (0.10%) variety, the highest potassium content is from the Sultan (0.46%) variety, the highest calcium content is from the Flower-22 (0.07%) variety and the highest the magnesium content was taken from Arıoğlu-2003 (0.26%) variety. The highest iron content is in Batem-Cihangir (27.34 mg kg-1) variety, the highest copper content is in Flower-22 (7.08 mg kg-1), the highest zinc content is in Sultan (29.35 mg kg-1), the highest manganese content NC-7 (20.61 mg kg-1) variety, the highest boron content was found in Florispan (26.99 mg kg-1) variety. According to the results of this study, varieties with different chemical compositions can be used in food and breeding studies.

Susceptibility of Historically Dominant Runner-Type Peanut Cultivars of the Southeastern United States to Early and Late Leaf Spot

A greenhouse experiment was conducted to test the hypothesis that cultivar use contributed to historical shifts in disease predominance patterns in the southeastern United States over the past 50 years. Passalora arachidicola, the causal agent of early leaf spot (ELS), and Nothopassalora personata, the causal agent of late leaf spot (LLS), were inoculated separately or together on three historically dominant cultivars, Florunner (1970 to 1996), Georgia Green (1996 to 2008), and Georgia-06G (2008 to present), and on one susceptible cultivar, Georgia Valencia. These results suggest that the transition from Florunner to Georgia Green could have contributed to the historical shift from LLS to ELS predominance observed in the 1990s, with sporulation potential as a possible mechanistic explanation. There was no evidence that Georgia-06G contributed to the resurgence of LLS in recent years. A negative association between ELS and LLS, where LLS is more suppressed in the presence of ELS, demonstrates that the dynamics of the ELS-LLS disease patterns are complex. Understanding factors that contribute to disease predominance will improve predictive abilities and support the development of cultural practices and fungicide programs specific to the pathogen that is expected to dominate.

Determination of Saturated and Unsaturated Fatty Acids in Second Crop Season Peanut Cultivation in the Eastern Mediterranean

In this study; the saturated and unsaturated fatty acid composition of 11 different peanut cultivars, Runner (Georgia Green) Virginia (NC-7, Masal, Halisbey, Wilson, Com, Brantley, Duzici-1) Spanish (Florispan, Nigeria-1), widely grown in the eastern Mediterranean Transition Zone were determined. The research was carried out for two years (2020 to 2021) under second crop season conditions in the trial areas of the Oil Seeds Research Institute. The experiment was set up in a randomized block design with 3 replications. In the research, palmitic acid, stearic acid, arachidonic acid, oleic acid, linoleic acid, oleic/linoleic ratio, iodin value, behenic acid, arachidic acid properties were investigated. The highest oleic acid ratio was obtained from Masal (79.71%), the highest palmitic acid from florispan (11.06%), and the highest linoleic acid (34.08%) from florispan. The behenic acid ratio was found between 2.51% (Wilson) and 3.14% (Georgia Green).

Genotypic, Temporal, and Tissue-type Effects on the Incidence of Tomato spotted wilt virus in Peanut (Arachis hypogaea L.)

Spotted wilt, caused by Tomato spotted wilt virus (TSWV), is one of the major diseases affecting peanut production in the southeastern United States. Growers use integrated disease management to control spotted wilt; however, disease resistance of a cultivar is the most important factor for managing this disease. This research evaluated genotypic, temporal, and tissue-type effects on the incidence of TSWV on each of four peanut cultivars. Four different types of tissues (leaf, root crown, old leaf and young leaf) were collected from each of four peanut cultivars (Florida-EPTM ‘113’, Florida-07, Georgia Green and Georgia Valencia) at five time points during the growing season. Immunoassays were conducted to detect viral presence. The incidence of TSWV infection increased over time during the growing season. Root crown tissue had higher infection than other types of tissue. Florida-EPTM ‘113’ had the lowest infection incidence. Compared to Florida-EPTM ‘113’, Florida-07 was seven times more likely to be infected by TSWV, while Georgia Green and Georgia Valencia possessed even higher probability, 18 times and 21 times higher, respectively. Florida-EPTM ‘113’ had significantly reduced TSWV infection likely due to slowing movement of the virus throughout the plant.

Antioxidant Assessment of Prenylated Stilbenoid-Rich Extracts from Elicited Hairy Root Cultures of Three Cultivars of Peanut (Arachis hypogaea).

Peanut produces prenylated stilbenoids upon biotic stress. However, the role of these compounds against oxidative stress have not been thoroughly elucidated. To this end, the antioxidant capacity of extracts enriched in prenylated stilbenoids and derivatives was studied. To produce these extracts, hairy root cultures of peanut cultivars Hull, Tifrunner, and Georgia Green were co-treated with methyl jasmonate, cyclodextrin, hydrogen peroxide, and magnesium chloride and then the stilbenoids were extracted from the culture medium. Among the three cultivars, higher levels of the stilbenoid derivatives arachidin-1 and arachidin-6 were detected in cultivar Tifrunner. Upon reaction with 2,2-diphenyl-1picrylhydrazyl, extracts from cultivar Tifrunner showed the highest antioxidant capacity with an IC50 of 6.004 µg/mL. Furthermore, these extracts had significantly higher antioxidant capacity at 6.25 µg/mL and 3.125 µg/mL when compared to extracts from cultivars Hull and Georgia Green. The stilbenoid-rich extracts from peanut hairy roots show high antioxidant capacity and merit further study as potential nutraceuticals to promote human health.

Resistance to fall armyworm (Lepidoptera: Noctuidae) feeding identified in nascent allotetraploids cross-compatible to cultivated peanut (Arachis hypogaea L.)

ABSTRACT Fall armyworm (FAW) is an economically devastating, invasive pest in Sub-Saharan Africa and can be a major pest in the Americas. This pest feeds on more than 80 plant species, including peanut, and threatens the food security of millions of people who rely on these crops in Sub-Saharan Africa. An integrated pest management strategy, including resistant crop cultivars, is needed to control FAW, since populations have been reported to develop insecticide resistance. Genetic sources of host resistance to FAW are limited in cultivated peanut; however, strong resistance to FAW was reported previously in peanut wild relatives. In this in vitro study, we tested diploid peanut relatives including A. ipaensis KG37006 (Ipa), A. duranensis 30060 (Dur), A. correntina 9530 (Cor9530), and A. correntina 9548 (Cor9548); allotetraploids including IpaCor95304x, IpaDur4x; F2 hybrids [A. hypogaea 13-1014 x IpaCor95304x]; and cultivated peanut lines A. hypogaea ‘13-1014′ and ‘Georgia Green' for FAW resistance to identify valuable materials in our breeding program. FAW development was measured by survival, larval weight, larval stage duration, pupation, pupal stage duration, moth emergence relative to pupation, and moth sex. All allotetraploids showed promise as donors for FAW resistance. This FAW resistance was derived primarily from A. ipaensis, but A. duranensis was also identified as a source of resistance, though more moderate. A high level of heterogeneity was found in A. correntina 9530, which likely contributed to the variable performance of this species in the bioassay. Producing hybrids and allotetraploids with wild Arachis species does not guarantee that each derived line from these crosses will be resistant, and since these lines are segregating, selection for resistance is still needed.

Doğu Geçit Bölgesinde Yetiştirilen Bazı Yerfıstığı (Arachis hypogaea L.) Çeşitlerinin Verim ve Verim Unsurlarının Belirlenmesi

This research; it was carried out under the main product conditions in order to determine the yield and yield components of some peanut varieties in the eastern passage region. Gazipasa, Batem-5025, Cihangir, Florispan, NC-7, Georgia Green, Sultan, Halisbey, Arioglu-2003 and Osmaniye-2005 were used in the experiment. In research, which was established in three repetitions according to the Randomized Complete Block Design, significant differences were detected in the statistical analysis regarding the features. As a result of the research; plant height 14.83-29.60 cm, branch number 5.10-7.96 piece/plant, 100 fruit weight 96.00-251.00 g, yield 352.01-553.45 kg da-1, internal rate 55.81- 72.98% and number of fruit per plant 35.04-70.66 piece/plant were showed change between. The highest yield was obtained from Cihangir variety with 553.45 kg da-1, while the lowest yield was obtained from Gazipasa variety with 352.01 kg da-1.

Inheritance of a Novel Heterozygous Peanut Mutant, 5-Small Leaflet

ABSTRACT An unusual 5-Small Leaflet mutant plant was found within the ‘Georgia Green' runner-type peanut (Arachis hypogaea L.) cultivar. Subsequent selfing has not established a true-breeding 5-Small Leaflet genotype. It continues to segregate normal and 5-Small Leaflet plants but with a reduced number of normal leaf plants upon selection for 5-Small Leaflet phenotypes after several self-generations. F1, F2, F3, and F4 data suggests that the 5-Small Leaflet trait is dominant or possibly pseudo-dominant. Likewise, the 5-Small Leaflet mutant can only be used as a pollen parent in crosses, and it has approximately a 1:1 ratio of elongated to normal stigmas, respectively, on individual plants. This is an example of a novel heterozygous peanut mutant plant found within the cultivated allotetraploid peanut.

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.

COMPARISON OF AGRONOMIC AND QUALITY CHARACTERISTICS OF SOME PEANUT (Arachis hypogaea L.) VARIETIES GROWN AS MAIN AND DOUBLE CROP IN MEDITERRANEAN REGION

This study was conducted at the University of Cukurova, Faculty of Agriculture in 2013 and 2014 as a main and double crop growing season. The objective of this study was to compare of agronomic and quality characteristics of some peanut (Arachis hypogaea L.) varieties grown as a main and double crop. The experimental design was a Randomized Complete Block (RCBD) with three replications. The Halisbey, Sultan, Osmaniye-2005, Arioglu-2003, Batem-5025, NC-7, Flower-22, Flower-32, Flower-36, Brantley, Wilson (Virginia market type), Florispan (Spanish market type), Georgia Green (Runner market type) and Spantex (Valencia market type) varieties were used as a plant material in this research. Pod number and pod weight per plant, 100 seed weight, shelling percentage, oil and protein content, pod and kernel yield per hectare values of varieties were compared. The average pod number, pod weight per plant, fancy pod percentage, protein and oil percentage, pod and kernel yield values of peanut varieties were higher in main crop than in double crop, whereas 100 seed weight and shelling percentage were higher in double crop than in main crop growing season. According to a two-year average, the pod yield per hectare of peanut varieties varied between 3366-8796 kg ha-1 and 3621-7094 kg ha-1 main and double crop growing season, respectively. The average pod yield of peanut varieties were 6177 kg ha-1 in main cropped, it was decreased to 5456 kg ha-1 in double crop growing season. The highest pod yield was obtained from Sultan and Osmaniye-2005 varieties in both growing seasons.

Peanut Peg Strength and Associated Pod Yield and Loss by Cultivar

ABSTRACT Peanut (Arachis hypogaea L.) peg strength and associated pod yield and digging loss were documented for nine cultivars and two breeding genotypes across three harvest dates (early, mid, and late season) at two Southwest Georgia locations during 2010 and 2011. Cultivars selected were Georgia Green, Georgia Greener, Georgia-02C, Georgia-06G, Georgia-07W, Georgia-09B, Georgia-10T, Florida-07, Tifguard, and advanced breeding lines EXP27-1516 and TifGP-2. Prior to digging, a minimum of three peanut plants from each plot were selected and excess stems and leaves were removed with scissors leaving individual peanut pegs and pods with about 5-cm of stem. Each peanut pod was placed in a “U” shaped metal bracket attached to an electronic force gauge and the stem was pulled manually until the pod detached. After digging and combining, a tractor-mounted scavenger machine was used to collect pods remaining in the soil. Peg strength was greater at Dawson (6.14 N) compared to Tifton (5.28 N) in 2010 but were similar in 2011 (4.51 and 4.39 N, respectively). Dawson had consistently higher yields (5326 kg/ha) and lower pod loss (562 kg/ha) compared with Tifton (3803 kg/ha and 936 kg/ha, respectively). Peanut cultivars with greater peg strength across locations were Georgia-06G, Florida-07, and Georiga-02C. Cultivar Georiga-06G showed the greatest yield across locations and years. Other cultivars may have had stronger peg strength, greater pod yield, or lower pod loss but none were more consistent than these three cultivars across years, locations, and harvest dates.

Spotted Wilt in Peanut as Impacted by Genotype Resistance, Planting Date, and Plant Population

Spotted wilt disease of peanut (Arachis hypogaea L.), caused by tomato spotted wilt virus (TSWV), has impacted peanut production for growers in the southeastern United States since the mid‐1990s. No single intervention can manage the disease sufficiently, but when used together, planting date, plant population, and cultivar selection can minimize risk of losses. The effects of planting date, plant population, and cultivar on spotted wilt were assessed in a field experiment over three consecutive years (2010–2012) near Marianna, FL. Evaluation included three visual measures of disease symptoms (rating scale 1–10, disease intensity rating 0–30, and testa symptomology), two measures of stand counts (emerged plants and tap root counts), and immunological assessment of the presence of TSWV in root crowns, pod yield, and grade. There was no effect of planting date on spotted wilt symptoms on foliage, on the testa, or on TSWV infection. Foliar symptoms of spotted wilt were found in all peanut cultivars, with ‘Georgia Green’ displaying more symptoms than the other three cultivars and ‘UFT‐312’ less than other cultivars. Immunological results found 10% or fewer plants of ‘Florida EPTM ‘113’’ and UFT‐312 infected with TSWV compared with 44% for ‘Florida‐07’ and 67% for Georgia Green. Immunological results showed that TSWV is present in about 50% of the plants of the moderately resistant cultivars Georgia Green and Florida‐07, which represent those commonly grown in the southeastern United States. This may indicate high risk for disease loss in those cultivars compared with Florida EPTM ‘113’ and UFT‐312, which possess a different source of resistance and had ≤10% infected plants. The cultivars Florida EPTM ‘113’ and UFT‐312 display a superior level of resistance that may override other factors, such as planting date and plant population, in years with high disease pressure.

Cultivar‐Specific Changes in Peanut Yield, Biomass, and Allergenicity in Response to Elevated Atmospheric Carbon Dioxide Concentration

Intraspecific variation in response to rising atmospheric carbon dioxide concentration [CO2] could be used as a means to begin selection for improved quantitative or qualitative characteristics for a given crop. Peanut (Arachis hypogaea L.) is a leguminous crop of global importance; however multiyear field assessments of intraspecific variation in yield or seed quality in regard to rising atmospheric [CO2] are scarce. In the current study, we examined the seed yield, above‐ground biomass, and concentration of a seed storage protein and primary allergen (Ara h 1) for two peanut cultivars with distinct morphologies, ‘Virginia Jumbo’ and ‘Georgia Green’, grown in open‐top field chambers at ambient or ambient + 250 µmol mol−1 [CO2] for a 2‐yr period. Significant differences in cultivar, [CO2], and cultivar × [CO2] were observed for above‐ground biomass and seed (peanut) yield, with Virginia Jumbo showing a consistently greater increase relative to Georgia Green in response to elevated [CO2]. The greater quantitative response of Virginia Jumbo to [CO2] was also concurrent with a significant increase in the concentration of Ara h 1 for this cultivar, which, in turn, was negatively correlated with overall protein concentration. While preliminary, these results indicate that selection opportunities exist to match yield increases to rising [CO2] for peanut through genetic or phenotypic selection; in addition, these are also the first data to show that [CO2]‐induced qualitative changes, particularly in regard to increased allergen concentration, should also be considered to address food safety concerns.

The Impact of Genotype × Environment Effects on Runner‐Type Peanut Seed Vigor Response to Temperature

Experiments conducted from 2007 to 2012 evaluated the genotype × environment effects on breeder seed of eight peanut (Arachis hypogaea L.) cultivars grown under similar production practices. Seed germination and vigor by plot replication were evaluated in Petri‐dishes incubated over a thermal gradient ranging from 12 to 36°C at approximately 1.0°C increments. Growing degree day (GDD) accumulation for each temperature increment was calculated based on daily mean temperature measured by thermocouples. Lorentzian distribution models were used to establish the temperature and time (hours) to maximum germination. With respect to maximum germination and temperature; Georgia‐07W (23.9°C) < Florida‐07 (25.0°C) < Georgia Greener (25.2°C) < Georgia‐06G (25.3°C) = Tifguard < Georgia Green (26.4°C) < Georgia‐09B (27.1°C) = Georgia‐02C. Nonlinear regression indices from logistic growth curves with three parameters were used to elucidate seed germination by cultivar. These data included maximum indices of germination for each cultivar by year establishing parameter estimates using nonlinear regression, GDD value at 80% germination (Germ80), and temperature required by each cultivar for optimum germination. Peanut cultivar vigor varied by year with respect to overall GDDs to reach Germ80 and maximum germination (b0). Ranking of cultivars by GDD to reach Germ80 were: Georgia Green < Georgia‐02C < Georgia‐06G = Georgia Greener < Georgia‐09B < Georgia‐07W < Tifguard < Florida‐07. This indicates that Georgia Green had much greater vigor than Florida‐07 over the course of the experiments. Georgia‐06G peanut seed were consistent with respect to germination, Germ80, and b0. All cultivars exhibited phenotypic variation by year, with genotype consistency across years.Core Ideas Peanut cultivars evaluated exhibited phenotypic vigor variation by year, with genotypic stability across years. This form of evaluation provided an indication of vigor which may assist breeders in determining the success of the cultivar over a range of temperatures. Larger seeded peanut cultivars exhibited less vigor than smaller seeded cultivars.

Effects of new field resistant cultivars and in-furrow applications of phorate insecticide on tomato spotted wilt of peanut

Field experiments were conducted at Tifton, Georgia from 2008 to 2014 to determine the effects of new peanut (Arachis hypogaea) cultivars and in-furrow applications of phorate insecticide on severity of tomato spotted wilt (TSW) caused by Tomato spotted wilt virus. Several cultivars, including Florida-07, Georgia-06G, Georgia-07W, Georgia Greener, and Tifguard, had final incidence of TSW that were less than that of Georgia Green. In-furrow applications of phorate insecticide reduced incidence of TSW in Georgia Green in three experiments in which that cultivar was included. In-furrow application of phorate insecticide reduced incidence of TSW in most cases where incidence in nontreated plots was 10% or higher. Cultivars Georganic, and Georgia-10T, had final incidence of TSW that was lower than that of Georgia-06G, or Florida-07 within nontreated plots across 2011–2012. Georgia-10T and Georgia-12Y had final incidence that was lower than that of Georgia-06G, Georgia-07W, Georgia-09B and Georgia Greener across insecticide treatments in 2013. In-furrow application of phorate increased yields across cultivars in 2008–2009, and increased yield of Georgia-09B in 2010. In most other cases, phorate had no significant effect on yield. With higher levels of field resistance in most of these cultivars, especially those such as Georgia-12Y, benefits from use of phorate insecticide for TSW suppression were small, and typically did not result in yield increase. Based on these results, several of these cultivars should allow greater flexibility for insecticide choice for thrips management without increasing the risk of losses to TSW.