Sound Mature Kernels Research Articles

Effects of Drought on Florunner Peanuts1

AbstractDroughty conditions are implicated in causing low yields, poor grades and germination, and an increased incidence of aflatoxin in the peanut (Arachis hypogaea L.). However, very little is known as to when in the growth cycle drought is most critical. Effects of five drought treatments on peanut leaf diffusive resistance, yield, and quality characteristics were studied on rainfall‐protected plots of Tifton loamy sand, a member of the fine, loamy, siliceous, Thermic Plinthic Paleudults. Early, middle, and late drought periods of short duration (35 days) and extended early and midseason droughts (70 days) were imposed by withholding irrigation. Yield, percent sound mature kernels (SMK), germination, leaf‐water potential, and leaf diffusion resistances were measured. Under droughty conditions, leaf‐water potential was lowest during midseason when evaporative demand was greatest. Leaf diffusion resistances, however, in creased with lateness and severeness of drought, reflecting leaf age and plant‐water stress. Leaf‐water potentials of −30 bars were recorded for several treatments during midseason, and values as low as −40 bars were recorded for the 35‐day midseason drought. Although the leaf‐water potentials of control plants decreased as the season progressed, they never became lower than −12 bars. In both stressed and nonstressed plants the diffusion resistances were frequently less on the upper than on the lower surfaces of leaves. Much of the plant‐water stress that developed during drought was relieved the day after irrigation and leaf diffusion resistances also returned to near normal. Vine weight was not decreased by any 35‐day drought, but was significantly reduced by 70‐day droughts.In general, drought progressively decreased yields as duration and lateness of occurrence in the season increased. The 70‐day extended early season drought caused the greatest reduction is SMK. The late season 35‐day and extended midseason 70‐day droughts lowered subsequent germination 5 and 9% respectively. These studies validate the importance of full‐season irrigation for peanuts in the Southeast. When full‐season irrigation may not be possible because of demands on the system, scheduling irrigation the latter part of the season appears next in importance.

Response of Early Bunch Peanuts to Calcium and Potassium Fertilization1

Abstract There is an immediate need for fertilization data concerning any newly released cultivar of peanuts (Arachis hypogaea L.). Field studies were conducted on three soil types to determine the effect of various rates of Ca and K on yield, quality and certain peanut diseases of the new peanut cultivar, Early Bunch. Calcium was applied at rates of 0, 123, 246 and 369 kg/ha and K was applied at levels of 0, 112 and 224 kg/ha. Fertilizer treatments were arranged in randomized block design with four replications. Yields, sound mature kernels (SMK), extra large kernels (ELK), and Pythium population and Sclerotium rolfsii (disease loci) incidence were determined. The yield, SMK, and ELK of Early Bunch peanuts were increased by Ca fertilization on Fuquay and Tifton loamy sand, but not on the Greenville sandy loam. The application of high levels of K reduced the yield of Early Bunch peanuts on Fuquay soil but had no effect on Tifton or Greenville soils. Increased Ca fertilization increased soil Ca on Greenville and Tifton soils but not on Fuquay soil. Potassium fertilization increased soil K on the Greenville soil but not on the Fuquay and Tifton soils. Some evidence was obtained that Ca fertilization reduced average Pythium (total) population in the Tifton and Fuquay soils and increased average incidence of Sclerotium rolfsii.

Arginine Maturity Index: Relationship With Other Traits in Peanuts1

Abstract ‘Spancross’, ‘Florunner’, and ‘Florigiant’ cultivars were used to determine the relationship between arginine maturity index (AMI) and other traits in peanut (Arachis hypogaea L.). Samples were taken weekly beginning 73 days after planting in 1973 and biweekly beginning 77 days after planting in 1974. AMI-1 was measured on fresh fruit and AMI-2 was measured on dry seed. The relationship between these two characters was greater than r = 0.85 in each cultivar tested. Both AMI-1 and AMI-2 were positively correlated to percent of other kernels and negatively correlated to pod yield, and percentages of total sound mature kernels, total kernels, dry matter, and mature seed. Among these correlations AMI-pod yield was weakest, whereas AMI-percent of total sound mature kernels was strongest. The quadratic polynomial, Y = a + bx + cx2, was used to fit the distribution curve for each trait. Florunner and Florigiant appeared to have similar patterns in all traits except percent of mature seed, but they differed from Spancross in these traits.

Methyl Bromide Fumigation of Farmers Stock Peanuts In Flat Storage1,2

Abstract Farmers stock peanuts, bulk stored inside large warehouses, were fumigated for 24 hr with methyl bromide (bromomethane) after thorough sealing of the facilities. Temperature of the peanuts varied from 21.8° to 26.8° C and gas concentrations monitored in the headspace above the peanuts decreased from 20.1 to 12.2 mg/liter during fumigation. Gas concentrations in the mass varied considerably during fumigation, being highest at the bottom of the peanuts. Gas concentrations decreased to less than 1 mg/liter after 48 h of aeration. Although tremendous populations of insects existed before fumigation, no insects survived the treatment. Bromide residues were much below the tolerance on the peanuts, although looseshelled kernels accumulated slightly higher residues than did sound mature kernels from pods. The success of the fumigation was attributed to the good construction of the warehouses and to the thorough sealing performed before the fumigation.

Response of Five Peanut Cultivars to Gypsum Fertilization On Soils Varying in Calcium Content1

Abstract Experiments were conducted to characterize the response to Ca of two recently released peanut (Arachis hypogaea L.) cultivars, ‘Tifrun’ and ‘Early Bunch’ and to compare their response to that obtained from ‘Florunner’, ‘Florigiant’, and ‘NC-Fla 14’. Gypsum (CaSO4•2H2O, approximately 72% CaSO4) was applied at rates of 0 and 1,121 kg/ha in a split plot design using the above cultivars. The experiment was conducted on Fuquay loamy sand low in Ca content and on Greenville sandy loam relatively high in Ca content. Yield, percent sound mature Kernels (% SMK), percent extra large kernels (% ELK), and percent oil in the seed were measured. The peanut cultivars differed in their response to soil Ca level and to Ca fertilizaton. Gypsum applications did not increase % SMK and yield of Florunner significantly when soil Ca content was low and pH adequate, whereas the other four cultivars produced large increases in these factors. Gypsum applications to the low Ca soil with high pH increased the percent oil 4.0% for all varieties every year. The response of Tifrun and Early Bunch to gypsum fertilization was similar to Florigiant and NC.FLA 14 Tifrun quality factors and yields were comparable to Florunner on the Greenville soil without supplementary Ca, whereas Ca fertilization of the Fuquay soil was necessary. Early Bunch was similar to Florigiant and NC-Fla 14 in both yield and quality factors.

Peanut Seed Germination as Related to Soil Water Regime During Pod Development1

AbstractThe problem of poor peanut (Arachis hypogaea L.) seed germination has appeared to follow exceptionally dry years in Georgia; consequently, the interaction of soil water availability during the growing season and subsequent seed germination were studied. These results are a composite of 4 years of study under controlled rainfall shelters on Tifton loamy sand, a member of the fine‐loamy, siliceous, thermic Plinthic Paleudults, at six soil water levels. Soil water levels involved irrigation at specified soil water tensions in surface 30 or 60 cm. Soil water tension ranged from + 0.2 to > 15 bar. Good germination of all varieties was obtained when the average soil water tension in the surface 30 cm was maintained at less than 0.6 bars. On the other hand, allowing ‘Florigiant’ to reach a soil water tension greater than 15 bars during the growing season lowered its percentage of sound mature kernels 34%. Of those sound mature kernels, germination was lowered on an average 20%. By contrast, under the similar treatment, SMK's of ‘Florunner’ and ‘Tifspan’ were lowered 22 and 7%, respectively, and the germination of either cultivar was lowered only about 5%. Thus, the large‐seeded Virginia type peanut, Florigiant, was found to be the most susceptible to droughty soil conditions. Irrigation appears to be good insurance against poor peanut seed germination in the following year.

Evaluation of Early Generation Testing in Peanuts1

Abstract Six lines representing three botanical varieties, and crosses made in diallel among the six lines were grown at two locations to determine the value of early generation testing in peanuts (Arachis hypogaea L.). Fruit length, percentage sound mature kernels, and percentage fancy size pods of the crosses bulked and measured in F5 generation were correlated with similar measures in F2 generation. F2 generation cross means for yield were not correlated with F5 cross means. Estimates of general combining ability were significant and of greater magnitude than specific combining ability estimates for both F2 and F5 generations for all traits except yield. The average performance of a parental line in crosses in the F2 generation was correlated with its average performance in crosses in the F5 generation for yield, fruit length, sound mature kernels, and fancy size pods. The highest yielding line from nine of the 15 crosses selected using a modified pedigree method equalled or exceeded the yield of the high parent for that cross. Yields of the highest yielding selections, however, were not correlated with the yield of either the F2 or F5 generations of the crosses grown in bulk. Early generation testing in peanuts of crosses between lines representing different botanical varieties appears to be a useful breeding procedure for traits such as fruit length, sound mature kernels, or fancy size pods but has limited value in selecting for yield.

Effect of Calcium and Irrigation Treatments on Peanut Yield, Grade and Seed Quality1

Abstract The effect of irrigation and/or Ca (calcium) application on yield, grade and seed quality was studied using Florigiant peanuts planted on three dates. Calcium application resulted in a small, but consistent, yield increase at all planting dates. Irrigation resulted in a large yield response on early planted peanuts and no response on late planted ones. Grade, specifically sound mature kernel percentage, was improved by both Ca and irrigation treatments but the effects were only slightly additive. Similar interaction effects were noted as these treatments increased the germination percentage of the seed produced and decreased the percentage of kernels with the form of damage termed dark plumule. Both treatments also decreased the amount of watery hypocotyl damage and increased the Ca concentration in the seed. Germination was 89 to 94% when the seed Ca level was greater than 420 ppm, but fell linearly to 52% when the seed Ca decreased from 420 to 200 ppm.

Responses of Three Peanut Cultivars to Gypsum1

AbstractThe differential response of peanut (Arachis hypogaea L.) cultivars to soil applications of Ca has been established for many years. Recent research reports, however, have indicated that peanut cultivars respond similarly to Ca application. This may result in part from new peanut cultivars differing in their response to Ca. Experiments were therefore conducted on a low Ca soil to measure responses of three commonly grown peanut cultivars to soil‐applied Ca.Gypsum was applied at 0 and 1,121 kg/ha in a split‐plot design using ‘Florunner,’ ‘Florigiant,’ and ‘NC‐Fla 14’ peanut cultivars. Other nutrients were applied uniformly. Yield, sound mature kernels (SMK), extra large kernels (ELK), and % N and oil in the seed were measured.Results from this experiment show that gypsum had no effect on yield or sound mature kernels of Florunner peanuts. Florunner peanuts produced higher yields and grades than Florigiant or NC‐Fla 14, regardless of treatments. Gypsum application to Florigiant and NC‐Fla 14 peanuts increased yields, sound mature kernels, and extra large kernels. In general, gypsum increased the % oil in all cultivars. Florigiant contained less oil than the other cultivars. Nitrogen content of the seed of all cultivars was reduced by gypsum application. These data indicate that on low Ca soils Florunner peanuts can produce higher yields and quality with or without gypsum, while Florigiant and NC‐Fla 14 need gypsum fertilization to increase yield and improve quality.

Effects of Herbicides, a Nematicide and Rhizobium Inoculant on Yield, Chemical Composition and Nodulation of Starr Peanuts (Arachis hypogaea L.)1

Abstract Most peanut (Arachis hypogaea L.) fields of the Southern Coastal Plain are treated with either vernolate (S-propyl dipropylthiocarbamate) or benefin (N-butyl-N-ethyl-a,a,a-trifluoro-2, 6-dinitro-p-toluidine) or a combination of these two herbicides to control certain weeds. The nematicide DBCP (1,2-dibromo-3-chloropropane) is also used in some fields. Field and greenhouse experiments were conducted to determine the effect of vernolate, benefin, DBCP, and Rhizobium sp. on nodulation, yield, quality, and chemical composition of ‘Starr’ peanuts. The application of herbicides, nematicide, and inoculant had no significant effect on yield, sound mature kernels, or ether extract of ‘Starr’ peanuts. The N content of the leaf and seed and the number of nodules were not affected by the treatments. Nematode infestation was low and did not affect yield. In the greenhouse studies, the application of lime, herbicides, or fertilizer did not affect certain morphological characteristics of the plant or N content of the peanut leaves. Nitrogen fertilization increased the weight of the peanut foliage.

Combining Ability Estimates in Arachis Hypogaea L. III. F2 Generation of Intra- and Intersubspecific Crosses1

Abstract A hybridization program was initiated to investigate the breeding potential of crosses among diverse peanut (Arachis hypogaea L.) lines. Fifteen crosses in F2 generation generated by crossing six peanut lines representing Valencia, Virginia, and Spanish botanical varieties in diallel without reciprocals were used to estimate combining ability in drilled and space-planted tests. Estimates of both general (GCA) and specific (SCA) combining ability were significant for percent extra large kernels, percent sound mature kernels, kernels/kg, pod length, and yield measured in the drilled test. The GCA estimates were also significant for all characters measured in the space-planted test, while estimates of SCA were significant for five of the six characters. Estimates of GCA were of greater magnitude than SCA estimates for all characters except one. A Spanish line, C2, had the highest GCA effects for yield and sound mature kernels in both drilled and space-planted tests. Although most F2 cross means, especially for the intersubspecific crosses, were less than the midparent value, the presence of transgressive segregants indicated an opportunity for breeding improvement. The depression of F2 means probably resulted from recombination of genes responsible for adaptation of the parental lines. Comparison of results from the space-planted and drilled tests indicates that data from space-planted tests can provide useful information on the performance of crosses in early generation.

Effect of Plowing Date and Certain Crop Rotations on Peanut Productivity1

Abstract The relationship of certain land management systems to productivity and pod breakdown disease incidence in peanuts (Arachis hypogaea) was studied in Virginia during 1971–74. Main treatments were three dates of moldboard plowing prior to planting peanuts in the rotations. Splitplot treatments were 2-year rotations: (I) peanuts followed by rye (Secale cereale) winter cover crop then corn (Zea mays) followed by rye winter cover crop; (II) peanuts followed by rye winter cover crop then soybeans (Glycine max) followed by no winter cover crop (except weeds); (III) peanuts followed by rye winter cover crop then no summer crop (residue of unharvested rye) nor cover crop planted; (IV) peanuts followed by rye winter cover crop then corn followed by fallow in winter, weeds prevented. Dates of plowing treatments affected peanut productivity most. Gross crop values and yields in plots plowed in December were 7%, and 18-to-20%, respectively, higher than when plots were plowed in March or May. Sound mature kernel contents also were lower for the later plowing dates. Differences among rotation treatment means occurred only when plots were plowed in May. Gross crop values were higher for rotation I than for rotation III and IV. In 1974, gross crop values obtained from plots plowed in March in rotation IV were equivalent to those from plots plowed in December. None of the treatments differentially affected pod breakdown disease significantly. However, the percentage of rotted pods averaged somewhat lower in plots plowed in December.

Boron, Calcium, and Potassium Interactions in Spanish Peanuts

AbstractExperiments were conducted in the field and greenhouse to evaluate interactions between application of B, Ca (gypsum) and K upon yield and quality of ‘Comet’ variety Spanish peanuts (Arachis hypogaea). In the greenhouse, using Eufaula fine sand, peanuts received factorial treatment combinations of three rates of B (0, 0.25, and 0.50 ppm), three rates of Ca (0, 88, and 176 ppm as gypsum), and three rates of K (25, 50, and 100 ppm). Factorial treatment combinations of three rates of B (0, 0.56, and 1.12 kg/ha), and three rates of Ca (0, 65, and 130 kg as gypsum/ha) were applied under field conditions at three locations.Under greenhouse conditions, significant interactions between the effects of B and Ca on growth and quality were observed. High Ca levels in the absence of applied B resulted in increased yields, lower seed quality (percent sound mature kernels), and extremely large increases in amounts of internal damage (due to B deficiency). No significant difference in yield response to B and Ca applications were found under field conditions. Peanuts showed a significant B by K interaction. Application of B with rates of potassium resulted in small increases in yield, except at the highest B and K levels where yields were reduced.

Assessing Boron Needs for Improving Peanut Yield and Quality

AbstractThree experiments were conducted to determine requirements of boron (B) for Spanish peanuts (Arachis hypogaea); (i) three rates of B were applied in solution to soil surfaces at 17 field locations, (ii) two rates of B were applied to soil at various stages of growth, and (iii) four B carriers were compared. Soil samples were collected at planting time. Leaf and petiole samples were collected 30 and 60 days after planting. The relationship of the occurrence of internal damage to initial soil B levels and concentration of B in plant tissue were evaluated. The effects of time, rate, and B carrier were also compared.Boron deficiency was found in more than 50% of the field locations. Boron application did not increase yields of peanuts or improve seed quality as measured by yield of sound mature kernels. The occurrence of internal damage from B deficiency (IDB) was shown to be related to hot‐water‐soluble soil B and to B content in young leaves and petioles. No IDB was found at locations with a hot‐water‐soluble soil B level > 0.15 ppm. Peanuts from plants with B concentration in young leaf tissue between 26 to 30 ppm at 30 and 60 days after planting were free of IDB. Boron applied as late as 60 days after planting was effective in eliminating IDB. No difference in the effectiveness of the four B carriers was found.

Change in Grade of Farmers' Stock Peanuts Stored in the Southwest

Abstract The effects of storage time on the extent and cause of grade reductions of farmers' stock Spanish peanuts harvested in the Southwest are discussed in this paper. This study was based on 184 randomly selected lots of farmers' stock peanuts sampled from 31 buying points throughout the Southwest area. Results of this research indicate that there was a significant decrease in the grade (sound mature kernels plus sound splits) with storage time and that this decrease occurred within the first 5 days of storage. The grade decreased from an initial average value of 71.3 to 70.3 after the 5-day storage period. There was a continuing decrease in grade with increased storage time; however, the change after the first 5 days of storage was not found to be significant. Decrease in grade results in an annual loss of approximately 2.26 million dollars in the Southwest peanut producing area. The principal cause for this reduction was determined to be the shift of the weight ratio of hulls and kernels during storage while only a small part of the grade loss was due to kernel shrinkage. The method of drying and grading had a significant influence on the decrease in grade. Mechanically dried peanuts lost 1.8 percentage points in grade during a 90-day storage preiod compared to only 0.3 percentage points for field-dried peanuts.

Effects of Spacing and a Growth Regulator, Kylar, on Size and Yield of Fruit of Virginia‐Type Peanut Cultivars1

AbstractThe reduction in plant size of peanuts (Arachis hypogaea L.) by genetic and chemical methods could result in increased productivity with the use of higher plant populations. The effects of increased plant populations on the yield and size of fruit of two Virginia‐type peanut cultivars, ‘NC 17’ and ‘NC 5,’ were investigated in factorial experiments by the use of four interrow and two intrarow spacing treatments and a growth regulator, Kylar. Interrow spacings less than 91.4 cm did not significantly increase the yield and had little effect on fruit size. The cultivars responded differently to Kylar. Seed and fruit size, and yield of NC 17 were reduced by the application of 1.121 kg/ha of Kylar. A similar application of Kylar to NC 5 reduced the fruit size but had no significant effect on yield or sound mature kernels. Both cultivars had higher yields at the 12.7‐cm than at the 25.4‐cm intrarow spacing. Increases in populations of plants reduced in size by genetic or chemical methods does not necessarily lead to an increase in productivity. Present methods of intra‐ and interrow spacings should not be changed for these two cultivars although plant size is reduced for NC 17 and can be reduced chemically for NC 5.

INFLUENCE OF DRYING TEMPERATURE AT HARVEST ON MAJOR VOLATILES RELEASED DURING ROASTING OF PEANUTS

Sound mature kernels of Spanish and Runner‐type peanuts harvested from two crop years were dried at four different temperatures (stack cured, 110, 135 and 160°F). Immediately after drying, the peanuts were shelled and roasted; the volatiles released during the roasting process were collected and quantified. Higher drying temperatures resulted in an increase in hydrogen sulfide, total base, dicarbonyl compounds and total carbonyls (hydrazones). Total volatile carbonyls appeared to be the best indicator of the effects o drying temperatures.

Limiting temperature and relative humidity for aflatoxin production by Aspergillus flavus in stored peanuts.

AbstractSound mature kernels, broken mature kernels, immature kernels and unshelled cured Early Runner peanuts were inoculated with spores ofAspergillus flavus and incubated up to 84 days in controlled environment cabinets. In a series of experiments temperatures ranged from 8 to 49 C in combination with 98±1% relative humidity (RH); in others RH was varied from 70% to 99% at 30±1/2 C and from 83% to 99% at 20±1/2 C. Samples were removed after 7, 21, 42 and 84 days of incubation and assayed for aflatoxin, free fatty acids and peanut kernel moisture. Aflatoxin was formed in sound mature kernels at 40 C and 14 C and in broken mature kernels at 13 C, but none was formed at 41 C after 21 days or at 12 C after 84 days in 98±1% RH. The limiting temperatures for aflatoxin formation in peanut kernels with intact shells were 41 C for 21 days and 16 C for 84 days of incubation. The limiting RH at 30 C for aflatoxin production in sound mature kernels was 84%, whereas in broken mature and immature kernels it was 83% and in kernels from unshelled peanuts the limiting RH was 86% for 84 days of incubation. The limiting RH at 20 C for sound and broken mature kernels was 83%, whereas it was 86% RH for immature kernels and 92% for kernels from unshelled peanuts. Free fatty acid formation was correlated with visible growth of fungi rather than with aflatoxin production. Aflatoxin formation was generally correlated with kernel moisture contents of 10% or higher.

Production of aflatoxin on peanuts under controlled environments

The influence of temperature, relative humidity, nature of the substrate, atmospheric gases, and other factors on growth and aflatoxin production by Aspergillus flavus in peanuts, Arachis hypogaea L. variety ‘Early Runner’, was investigated under controlled environments. Sound or broken mature kernels, immature kernels, and unshelled peanuts were inoculated with spores of A. flavus and incubated in 98 ± 1 per cent r.h. at temperatures ranging from 10 to 45°C, and also 30 ± 0·5°C in relative humidities ranging from 70 to 99 per cent. The substrate was either heat-treated (sterile) cured peanuts, surface-sterilized pods of freshly dug peanuts, or unsterile cured peanuts. Surface-sterilized, sound mature kernels were used in studies with atmospheric gases. Samples were removed after 7, 21, 42 or 84 days and assayed for aflatoxin, free fatty acids, and kernel moisture. The limiting relative humidity for aflatoxin production was 83 ± 1 per cent or higher at 30°C, varying with the substrate and length of the incubation period. The lower limiting temperature was 11–12 ± 1°C, whereas the upper limiting temperature was 40·5 ± 0·5°C at 98 ± 1 per cent r.h. Living peanuts in the shell were slightly less susceptible to invasion and aflatoxin formation than shelled kernels or heat-killed peanuts. Aflatoxin production in sound mature kernels decreased with increasing concentrations of CO 2 from 0·03 to 100 per cent. Reducing O 2 concentrations generally reduced aflatoxin production. Notable decreases in aflatoxin resulted when O 2 was reduced from 5 to 1 per cent in combination with 0, 20 or 80 per cent CO 2. Lowering temperature or relative humidity from optimum also reduced aflatoxin production. Aflatoxin production varied with strain of the fungus, maturity of the peanut, shake or stationary culture, and microbial interactions. Free fatty acid formation paralleled fungus growth rather than aflatoxin synthesis.

Effect of carbon dioxide, temperature, and relative humidity on production of aflatoxin in peanuts.

AbstractEffects of carbon dioxide (CO2) in combination with reduced relative humidities (RH) and temperatures on growth and aflatoxin production byAspergillus flavus in peanuts were investigated. Sound mature kernels of Early Runner peanuts were surface disinfested, inoculated withA. flavus, and incubated at various temperatures, RH, and CO2 concentrations. Visible growth, aflatoxin production, and free fatty acid (FFA) formation byA. flavus was inhibited at approximately 86% RH by 20% CO2 at 17C and by 60 and 40% CO2 at 25C. Aflatoxin and FFA levels decreased as RH decreased from approximately 99% to 92% to 86%. At a constant temperature, an increase in CO2 concentration caused a decrease in aflatoxin and percentage FFA; and, at a given CO2 concentration, lowering the temperature resulted in a decrease in aflatoxin and percentage FFA.