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Nitrogen (N) response studies in rice (Oryza sativa L.) are conducted to provide grower recommendations with economically optimum N rates (EONRs). This study was conducted to determine if experimental design alters the predicted EONR for rice. The effects of experimental design and soil texture on predicted EONR were investigated near Arcola, Greenville, Minter City, and Shaw, MS on soil textures ranging from sandy loam to clay. The response of rice grain yield to seven N fertilizer rates was fitted with a quadratic equation, and the quadratic trend was compared between the randomized complete block (RCB) and split-plot (SP) designs. No differences were detected between RCB and SP designs for rice grain yield response to N rate; therefore, either design, RCB or SP, would be appropriate for use in N response studies for rice.

Ratooning ability is important for sugarcane (Saccharum spp.), but due to time constraints relevant third ratoon yield data is not gathered before breeding selections are made. If third ratoon could be predicted, selections would improve. Machine learning (ML) techniques utilize yield variables to create predictors. Yield variables from 11 locations, 24 genotypes, and 20 cycles were used in a model to predict third ratoon-cane yield cross validated by cycle using ML and statistical techniques including Linear Regression, Random Forest, AdaBoost, Stochastic Gradient, Neural Network, Support Vector Machines, and k-nearest neighbors algorithm. Prediction error was measured as the difference between predicted and measured third ratoon cane yield. A model that partitioned overall prediction error into sources of variances indicated that location within cycle (52%) followed by genotype by location within cycle (10%) were the largest sources of error for predicting ratooning ability. Ratoon stalk number, sucrose and cane yield ranked highly toward predictions. The Adaboost (AB) ML predictors of third ratoon cane yield had lower experimental error, when compared to second ratoon as a third ratoon predictor. However, prediction by cycle was not consistently lower than second ratoon as a predictor. If unique locations were removed, then AB predictions had less error and better predictors of third ratoon than second ratoon in 75% of the cycles tested, thus demonstrating the potential and limitations of utilizing harvest and location data for ML predictions.

The differential dyeing (DD) method has been a subjective method for visually determining immature cotton fibers. We attempted to quantitate DD results and offer an efficient means of elucidating cotton maturity, without visual discretion. Image analysis of cotton color obtained with a scanner was performed and compared to spectrophotometrically measured color. Low, Medium and High micronaire (Mic) cotton standards were dyed, and we determined that blending the cotton yielded more precise color measurement; with the mean red, green and blue (RGB) values for a low Mic sample being: 101.6 ± 23.9, 83.1 ± 22.0 and 98.3 ± 23.1, respectively; while blending yielded RGB values: 121.6 ± 9.0, 98.8 ± 8.6 and 116.0 ± 8.9, respectively. Comparing RGB values to Mic, it was found that R and B color parameters do not show a trend, but G values decrease with increasing Mic indicating a decrease in G dye uptake with an increase in maturity. The conventional L*a*b* color space values were also obtained for the dyed cottons and compared to RGB and Mic results. The %CV for a* values are higher compared to L* and b* measurements: ∼31.9%, 18.9% and 8.6% for low, medium and high Mic samples, respectively. L* and b* decrease while a* increases with Mic, indicating an increase in R dye with an increase in maturity. The DD Bath method was found to be reliable, with R showing the greatest variances. G and a* values obtained were found to be the best correlation of differences in Mic.

Charcoal rot (CR), caused by the fungus Macrophomina phaseolina (Tassi) Goid. is a pervasive disease of economic significance on soybeans (Glycine max (L.) Merr.). Similarly, drought is the leading cause of yield loss in soybean worldwide. In this study, CR severity and seed yield were determined in irrigated and non-irrigated environments in 2011, 2012, and 2013 for thirteen soybean genotypes, nine of which were previously determined to be drought tolerant (DT). The objectives were to determine the severity of CR in the putative DT genotypes and to determine the over-all effect of CR on yield in irrigated and non-irrigated environments. Colony Forming Units (CFUs) at reproductive stage R7 were used to assess disease severity and classify each genotype's response to CR. A stress tolerance index (STI) was used to determine the relative impact of soil moisture stress (i.e. no irrigation) on the 13 genotypes. Over all three years in both irrigated and non-irrigated environments, five genotypes were consistently rated as moderately resistant to CR (MRCR) and three genotypes were consistently rated as susceptible to CR (SCR), whereas the responses of the remaining five genotypes varied between MRCR and SCR. Averaged over the three years, there was a wide range (0.36–1.09) of STI values among genotypes. Even though there was a consistent trend, there was a very weak relationship between STI and CFU's at the R7 growth stage. Regression analysis indicated that as CFUs at R7 increased, seed yield decreased, although the relationship was not significant in every year and irrigation environment. Nonetheless, across all years and irrigation environments, a pooled (global) slope indicated a yield loss of 11.5 kg ha−1 for every 1000 CFUs at R7. These data indicated that as CFUs at R7 increased, seed yield decreased in both irrigated and non-irrigated environments. However, as the relationship between CR disease severity and DT was minimal, it may be necessary to select for resistance to both traits using environments where both soil moisture stress and CR are high.

Research on sapodilla (Manilkara zapota) has been very limited. A field study was conducted to determine the yield potential, fruit quality traits, leaf nutrient composition, and scion/rootstock compatibility of ‘Prolific’ sapodilla grafted onto 16 sapodilla rootstock seedlings. For this purpose, seedlings (maternal half-sibs) of cultivars Adelaide, Arcilago, Aruz, Blackwood, Blocksberg, Guilbe, Hanna, Jamaica-1, Larsen, Mendigo-1, Gallera, Morning Star, Russel, Prolific, Timothe, and Vasallo-1 were used as rootstock seedlings and evaluated during 7 years of production at Isabela, PR. Year showed a significant effect on the number of fruit per hectare, yield, individual fruit weight, fruit length and diameter, and total soluble solids. Rootstock seedlings had a significant effect on the number of fruit per hectare, yield, and individual fruit weight but had no effect on other fruit traits. The year × rootstock interaction was not significant for any of the variables measured in the study. Rootstock seedlings ‘Timothe’, ‘Vasallo-1’, ‘Larsen’, and ‘Aruz’ had the highest 7-year mean for number and the yield of fruit averaging 4479 fruit/ha and 1245 kg·ha−1, respectively. ‘Timothe’ and ‘Vasallo-1’ significantly out yielded the ‘Prolific’ rootstock seedling. The number of fruit per hectare and corresponding yield obtained in this study were very low probably as the result of wind exposure, the presence of the fungus Pestalotia causing floral necrosis, or both. Scion/rootstock incompatibility was not the cause of the low yield performance of grafted trees. The average individual weight of fruit was 282 g and ranged from 264 to 303 g. Averaged over rootstock seedlings, leaf tissue nutrient concentration did not vary greatly over time. Moreover, tissue nutrient concentration was similar before and after fertilization events.

Purple seed stain (PSS) of soybean (Glycine max (L.) Merr.) is a prevalent seed disease. It results in poor seed quality and reduced seed lot market grade, and thus undermines value of soybean worldwide. The objectives of this research were to evaluate the reaction of selected soybean genotypes collected from 15 countries representing maturity groups (MGs) III, IV, and V to PSS, and to identify new sources of resistance to PSS based on three years of evaluation of natural field infection by Cercospora spp. in the Mississippi Delta of the U. S. In this study, 42 soybean genotypes were evaluated in 2010, 2011, and 2012. Seventeen lines including six MG III (PI 88490, PI 504488, PI 417361, PI 548298, PI 437482, and PI 578486), seven MG IV (PI 404173, PI 346308, PI 355070, PI 416779, PI 80479, PI 346307, and PI 264555), and four MG V (PI 417567, PI 417420, PI 381659, and PI 407749) genotypes had significantly lower percent seed infection by Cercospora spp. than the susceptible checks and other genotypes evaluated (P ≤ 0.05). These genotypes of soybean can be used in developing soybean cultivars or germplasm lines with resistance to PSS and for genetic mapping of PSS resistance genes. In addition, among these 17 lines with different levels of resistance to PSS, nine soybean genotypes (PI 417361, PI 504488, PI 88490, PI 346308, PI 416779, PI 417567, PI 381659, PI 417567, and PI 407749) were previously reported as resistant to Phomopsis seed decay. Therefore, they could be useful in breeding programs to develop soybean cultivars with improved resistance to both seed diseases.

The Rice Diversity Panel 1 (RDP1) was developed for genome-wide association (GWA) studies to explore five rice ( L.) subpopulations (, , , , and ). The RDP1 was evaluated for over 30 traits, including agronomic, panicle architecture, seed, and disease traits and genotyped with 700,000 single nucleotide polymorphisms (SNPs). Most rice grown in the southern United States is and thus the diversity in this subpopulation is interesting to U.S. breeders. Among the RDP1 accessions, ‘Estrela’ and ‘NSFTV199’ are both phenotypically and genotypically diverse, thus making them excellent parents for a biparental mapping population. The objectives were to (i) ascertain the GWA QTLs from the RDP1 GWA studies that overlapped with the QTLs uncovered in an Estrela × NSFTV199 recombinant inbred line (RIL) population evaluated for 15 yield traits, and (ii) identify known or novel genes potentially controlling specific yield component traits. The 256 RILs were genotyped with 132 simple sequence repeat markers and 70 QTLs were found. Perl scripts were developed for automatic identification of the underlying candidate genes in the GWA QTL regions. Approximately 100 GWA QTLs overlapped with 41 Estrela × NSFTV199 QTL (RIL QTL) regions and 47 known genes were identified. Two seed trait RIL QTLs with overlapping GWA QTLs were not associated with a known gene. Segregating SNPs in the overlapping GWA QTLs for RIL QTLs with high values will be evaluated as potential DNA markers useful to breeding programs for the associated yield trait.

Phomopsis seed decay (PSD), caused primarily by the fungal pathogen Phomopsis longicolla, is one of the most important diseases reducing seed quality and yield of soybean. Few cultivars have been identified as resistant. To identify new sources of resistance to PSD, 135 soybean germplasm accessions, originating from 28 countries, were field screened in Arkansas, Mississippi, and Missouri in 2009. Based on seed assays of natural field infection by P. longicolla in 2009, 42 lines, including the most resistant and susceptible lines, were reevaluated in the field in 2010, 2011, and 2012 with P. longicolla-inoculated and noninoculated treatments. Six maturity group (MG) III (PI 189891, PI 398697, PI 417361, PI 504481, PI 504488, and PI 88490), four MG IV (PI 158765, PI 235335, PI 346308, and PI 416779), and five MG V (PI 381659, PI 381668, PI 407749, PI 417567, and PI 476920) lines had significantly lower percent seed infection by P. longicolla than the susceptible checks and other lines in the same test (P ≤ 0.05). They appeared to have some levels of resistance to PSD. These new sources of PSD resistance can be used in developing soybean breeding lines or cultivars with resistance to PSD, and for genetic mapping of PSD resistance genes.

Pecan scab (caused by Fusicladium effusum) is the most economically destructive disease of pecan in the Southeast United States. Wet, humid conditions typical of the Southeast are known to provide conditions conducive to epidemics. A provenance collection of pecan from 19 locations representing the native range of the tree is located in Byron, Georgia, and was assessed for pecan scab severity in 1998, 2013, and 2014. There were significant differences among the 19 provenances (F = 5.6 to 62.5, P < 0.0001). Provenances from wetter locations (generally north of Texas) had the greatest proportion of scab resistant trees, while provenances from the drier southern areas (Texas and Mexico) tended to be the most susceptible to scab. The association with rainfall was borne out by correlation analysis (r = –0.625 to –0.823 [P < 0.0001 to 0.004]). Other factors consistently associated with scab severity included leaflet tilt and droop angle (r = –0.533 to –0.883 [P < 0.0001 to 0.02]). Multiple regression analysis demonstrated that leaflet droop angle was a particularly good predictor of provenance susceptibility. Leaflet characteristics vary with provenance location, and whether there is a direct relationship between scab severity and leaflet characteristics is not established. Estimates of heritability were not entirely consistent among years, but different methods were used to assess scab severity in 1998 (a 1 to 5 category scale) compared with 2013 and 2014 (the percent ratio scale). Despite using different methods, there was generally good agreement among years in regard to severity of disease on individual trees. In conclusion, trees from more northern populations (in areas with greater annual rainfall) are most likely to provide valuable and diverse sources of resistance to scab. The provenance collection contains a range of scab-resistant genotypes from diverse locations that can contribute to genetic improvement regarding scab resistance.

Phomopsis seed decay (PSD), caused by Phomopsis longicolla (syn. Diaporthe longicolla), is an economically important soybean disease causing poor seed quality. Planting resistant cultivars is one of the most effective means to control PSD. In this study, 16 commercially available maturity groups IV and V soybean cultivars, including two previously identified PSD-resistant and two PSD-susceptible checks, were evaluated for seed infection by P. longicolla in inoculated and noninoculated plots, and harvested promptly or with a 2-week delay in harvest. The test was conducted at Stoneville, Mississippi, in 2012 and 2013. Seed infection by P. longicolla ranged from 0.5 to 76%, and seed germination ranged from 18 to 97%. One MG IV cultivar (Morsoy R2 491) and five MG V cultivars (Progeny 5650, Progeny 5706, Asgrow 5606, Asgrow 5831, and Dyna-Gro33C59) had significantly (P ≤ 0.05) lower percent seed infected by P. longicolla than their respective susceptible checks and other cultivars in the same tests. Information obtained from this study will be useful for soybean growers and breeders for selection of cultivars for planting or breeding and future genetic studies in the development of cultivars with improved resistance to PSD.

Phosphorous (P) fate and transport models are important tools for developing and evaluating conservation practices aimed at reducing P losses from agricultural fields. Because all models are simplifications of complex systems, there will exist an inherent amount of uncertainty associated with their predictions. It is therefore important that efforts be directed at identifying, quantifying, and communicating the different sources of model uncertainties. In this study, we conducted an uncertainty analysis with the Annual P Loss Estimator (APLE) model. Our analysis included calculating parameter uncertainties and confidence and prediction intervals for five internal regression equations in APLE. We also estimated uncertainties of the model input variables based on values reported in the literature. We then predicted P loss for a suite of fields under different management and climatic conditions while accounting for uncertainties in the model parameters and inputs and compared the relative contributions of these two sources of uncertainty to the overall uncertainty associated with predictions of P loss. Both the overall magnitude of the prediction uncertainties and the relative contributions of the two sources of uncertainty varied depending on management practices and field characteristics. This was due to differences in the number of model input variables and the uncertainties in the regression equations associated with each P loss pathway. Inspection of the uncertainties in the five regression equations brought attention to a previously unrecognized limitation with the equation used to partition surface-applied fertilizer P between leaching and runoff losses. As a result, an alternate equation was identified that provided similar predictions with much less uncertainty. Our results demonstrate how a thorough uncertainty and model residual analysis can be used to identify limitations with a model. Such insight can then be used to guide future data collection and model development and evaluation efforts.

Ureides are the N-rich products of N-fixation that are transported from soybean nodules to the shoot. Ureides are known to accumulate in leaves in response to water-deficit stress, and this has been used to identify genotypes with reduced N-fixation sensitivity to drought. Our objectives in this research were to determine shoot ureide concentrations in 374 Maturity Group IV soybean accessions and to identify genomic regions associated with shoot ureide concentration. The accessions were grown at two locations (Columbia, MO, and Stuttgart, AR) in 2 yr (2009 and 2010) and characterized for ureide concentration at beginning flowering to full bloom. Average shoot ureide concentrations across all four environments (two locations and two years) and 374 accessions ranged from 12.4 to 33.1 µmol g−1 and were comparable to previously reported values. SNP–ureide associations within and across the four environments were assessed using 33,957 SNPs with a MAF ≥0.03. In total, 53 putative loci on 18 chromosomes were identified as associated with ureide concentration. Two of the putative loci were located near previously reported QTL associated with ureide concentration and 30 loci were located near genes associated with ureide metabolism. The remaining putative loci were not near chromosomal regions previously associated with shoot ureide concentration and may mark new genes involved in ureide metabolism. Ultimately, confirmation of these putative loci will provide new sources of variation for use in soybean breeding programs.

There are limited numbers of Escherichia coli isolate panels that represent United States food animal production. The majority of existing Escherichia coli isolate panels are typically designed: (i) to optimize genetic and/or phenotypic diversity; or (ii) focus on human isolates. To address this shortfall in agriculturally-related resources, we have assembled a publicly-available isolate panel (AgEc) from the four major animal production commodities in the United States, including beef, dairy, poultry, and swine, as well as isolates from agriculturally-impacted environments, and other commodity groups. Diversity analyses by phylotyping and Pulsed-field Gel Electrophoresis revealed a highly diverse composition, with the 300 isolates clustered into 71 PFGE sub-types based upon an 80% similarity cutoff. To demonstrate the panel's utility, tetracycline and sulfonamide resistance genes were assayed, which identified 131 isolates harboring genes involved in tetracycline resistance, and 41 isolates containing sulfonamide resistance genes. There was strong overlap in the two pools of isolates, 38 of the 41 isolates harboring sulfonamide resistance genes also contained tetracycline resistance genes. Analysis of antimicrobial resistance gene patterns revealed significant differences along commodity and geographical lines. This panel therefore provides the research community an E. coli isolate panel for study of issues pertinent to U.S. food animal production.

Contamination of maize ( Zea mays L.) with afla - toxin, produced by the fungus Aspergillus flavus Link, has severe health and economic conse - quences. Efforts to reduce aflatoxin accumula - tion in maize have focused on identifying and selecting germplasm with natural host resis - tance factors, and several maize lines with sig - nificantly reduced aflatoxin accumulation have been identified. p ast linkage mapping studies have identified quantitative trait loci (QTL) that consistently reduce aflatoxin levels in maize. In addition, an association mapping panel of 300 maize inbred lines was previously created specifically for the dissection of aflatoxin accu - mulation resistance. Here we report the results of a genome-wide association study (GWAS) using this panel of testcrossed maize hybrids. Each of the inbred parents of the testcrossed hybrids was genotyped by sequencing to gen - erate 261,184 robust single nucleotide polymor - phisms (SNps), and the entire panel was phe - notyped for aflatoxin accumulation following inoculation with A. flavus in multilocation, rep - licated field trials. results uncovered 107 SNp s associated with aflatoxin accumulation in one or more environments in the association panel at a probability level between 9.78  10 −6 and 2.87  10 −10 . Eight SNp trait associations were found with a false discovery rate (FDr) of less than 10% ( p < 3.83  10 −7 ). These SNps occur within the sequence of three uncharacterized genes. Variants in 25 other genomic regions showing high association values over more than one environment are also presented. These genomic regions are undergoing validation studies and will be of use to dissect the resistance to afla - toxin accumulation and improve this trait.

Rice (Oryza sativa L.) is often exposed to cool temperatures during spring planting in temperate climates. A better understanding of genetic pathways regulating chilling tolerance will enable breeders to develop varieties with improved tolerance during germination and young seedling stages. To dissect chilling tolerance, five assays were developed; one assay for the germination stage, one assay for the germination and seedling stage, and three for the seedling stage. Based on these assays, five chilling tolerance indices were calculated and assessed using 202 O. sativa accessions from the Rice Mini-Core (RMC) collection. Significant differences between RMC accessions made the five indices suitable for genome-wide association study (GWAS) based quantitative trait loci (QTL) mapping. For young seedling stage indices, japonica and indica subspecies clustered into chilling tolerant and chilling sensitive accessions, respectively, while both subspecies had similar low temperature germinability distributions. Indica subspecies were shown to have chilling acclimation potential. GWAS mapping uncovered 48 QTL at 39 chromosome regions distributed across all 12 rice chromosomes. Interestingly, there was no overlap between the germination and seedling stage QTL. Also, 18 QTL and 32 QTL were in regions discovered in previously reported bi-parental and GWAS based QTL mapping studies, respectively. Two novel low temperature seedling survivability (LTSS)–QTL, qLTSS3-4 and qLTSS4-1, were not in a previously reported QTL region. QTL with strong effect alleles identified in this study will be useful for marker assisted breeding efforts to improve chilling tolerance in rice cultivars and enhance gene discovery for chilling tolerance.

The pecan weevil, Curculio caryae (Horn) (Coleoptera: Curculionidae), is a key pest of pecans Carya illinoinensis ([Wangenh.] K. Koch) (Fagales: Juglandaceae). Control recommendations rely on broad spectrum chemical insecticides. Due to regulatory and environmental concerns, effective alternatives for C. caryae control must be sought for pecan production in conventional and organic systems. We explored the use of microbial biopesticides for control of C. caryae in Georgia pecan orchards. Three experiments were conducted. The first investigated an integrated microbial control approach in an organic system at two locations. Three microbial agents, Grandevo (based on byproducts of the bacterium Chromobacterium subtsugae Martin, Gundersen-Rindal, Blackburn & Buyer), the entomopathogenic nematode Steinernema carpocapsae (Weiser), and entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin, were applied to each treatment plot (0.6 ha) at different times during the season. A second experiment compared the effects of S. carpocapsae and B. bassiana applied as single treatments relative to application of both agents (at different times); survival of C. caryae was assessed approximately 11 mo after larvae were added to pots sunk in an organic pecan orchard. In a conventional orchard (with 1.0 ha plots), the third experiment compared Grandevo applications to a commonly used regime of chemical insecticides (carbaryl alternated with a pyrethroid). All experiments were repeated in consecutive years. The combined pest management tactic (experiment 1) reduced C. caryae infestation relative to non-treated control plots in both locations in 2014 and one of the two locations in 2015 (the other location had less than 1% infestation). In experiment 2, no differences among combined microbial treatments, single-applied microbial treatments or different numbers of application were observed, yet all microbial treatments reduced C. caryae survival relative to the control. In the third experiment, both Grandevo and standard chemical insecticide applications resulted in lower weevil infestation than the control (both years) and there was no difference between the insecticide treatments in 2014 although the chemical insecticide regime had slightly lower infestation in 2015. These results provide evidence that microbial biopesticides can substantially reduce pecan weevil infestations in organic and nonorganic systems.

Cotton breeders should have knowledge of traits that affect lint yield before embarking on a breeding program. Twelve diverse germplasm lines of upland cotton were used to investigate the effects of lint turnout, days to maturity, boll weight, number of bolls/plant, plant height, number of seeds/boll, boll width, boll length, seed index, number of locs/boll, number of fibers/seed, fiber density, on lint yield. The 12 lines were planted at two locations each during 2011 and 2012 at Stoneville, Miss. Simple correlation coefficients were subjected to path-coefficient analysis and direct and indirect effects were determined. Across all cultivar groups, lint turnout (0.52), plant height (0.43), number of bolls/plant (0.29), and boll weight (0.22) had the highest direct effects on lint yield. They were also positively and significantly correlated with lint yield. Boll length, fibers/seed, fiber density, number of locs/boll, and days to maturity were negatively correlated and with minimal impact on lint yield. D...

In approximately 25% of the sugarcane-producing countries worldwide, conventional sugarcane (Saccharum spp. hybrids) is exposed to damaging freezes. A study was conducted during the 2009 and 2010 harvest seasons to compare late-season freeze tolerance among three groups: commercial Louisiana sugarcane genotypes, early generation genotypes selected for cold tolerance in the U.S. Department of Agriculture sugarcane breeding programs at Houma, LA, and Canal Point, FL, and potential energycane genotypes selected for high total biomass per acre. Mannitol concentrations in cane juice following freezing temperatures were determined to evaluate levels of cold tolerance. Genotypes selected for cold tolerance in Houma, LA, had significantly more late-season freeze tolerance than commercial sugarcane genotypes and genotypes selected in Canal Point, FL. Genotypes showing the most cold tolerance were Ho02-146 and Ho02-152, and those that were most highly susceptible were US87-1006 and US87-1003 (early-generation breeding genotypes) and L99-233 (commercial genotype). Broad-sense heritability for late-season cold tolerance in the two-year study was estimated at g(2) = 0.78. The enzymatic mannitol analysis successfully differentiated high-fiber energycane genotypes from those from other sources.

Seed coat fragments (SCFs) reduce the marketability of cotton fiber, yarns and fabrics. It is particularly important to measure SCF content in the fabric because they cause severe dyeing and appearance defects. SCF content is greatly affected by cotton varieties, environmental conditions during crop development, and mechanical processing, but studying their effects in fabrics can be very tedious and time consuming. In this paper, we present an image analysis system for accurate and fast measurement of SCFs in greige fabrics, and the conditions of using the system for reliable and repeatable data. In the study, four different US cotton varieties were selected, and processed with regular manufacturing facilities. The relationship between sample size and precision of the image analysis system was determined through statistical analysis. It was found that the minimum sample size for each variety should consist of five camera images with a minimum of four fabric samples per variety with three replications, which gives a least significant difference (LSD) of 64.54 for dark speck count. Dark speck counts for the four fabrics tested ranged from 267.7 to 659.9. Increasing sample size will lower the LSD.

Characterization of cuticular hydrocarbons permits basic distinctions among colonies of Solenopsis invicta Buren, Solenopsis richteri Forel and their hybrids (Hymenoptera: Formicidae); thus, providing opportunities to investigate details of landscape ecology for this species complex and to assess levels of invasiveness. We introduce an alternative method for the cluster analysis of cuticular molecules of imported fire ants that is complementary to a widely-used method based on calculating cuticular hydrocarbon and venom alkaloid indices. Results from this GC-MS method were analyzed using various hierarchical and normal mixtures clustering methods to test the stability of group membership. Principal component and discriminant analyses were used to produce three-dimensional views of group separation. The relative proportions of 12 intensity peaks served to differentiate imported fire ant hybrids into four assemblages – hybrids closely allied with S. invicta, hybrids close to S. richteri, a ‘core’ hybrid gro...

Protein and oil are the most important components of soybean [Glycine max (L.) Merr.], and they have been shown to have an inverse relationship. As there is a growing demand for soybean oil-based diesel as an alternative fuel source, a better understanding of the protein–oil inverse relationship in conjunction with seed yield could be useful in determining the potential of soybean as a source of biodiesel. We retrospectively examined advanced soybean breeding lines from multiple breeding programs across the southern USA to determine associations between protein and oil and seed yield. The data analyzed were a subset of the Uniform Soybean Tests and consisted of 31 different soybean breeding lines and four checks grown at 10 locations in 2000, six locations in 2001, and eight locations in 2002. A progressive multiple regression analysis was used to develop a single equation describing seed yield over all entries, locations, and years as a function of five traits: oil content, protein content, maturity, lodging, and plant height. From this equation, the optimum plant type for maximum seed yield in the southern USA had either high oil (225 g kg−1) and low protein (385 g kg−1), or high protein (437 g kg−1) and low oil (190 g kg−1). Seed yield continues to be the dominant trait of selection in soybean breeding programs. This study demonstrates that high yield can be achieved with either high protein or high oil. Hence, there is potential for maintaining yield while improving soybean cultivars for oil production. Given the energy balance between fossil-derived and soy-derived diesel, if soy-based biodiesel is to be a significant option, an increased focus on developing high-oil/high-yield soybean needs to occur.

Mound construction by imported fire ants (Solenopsis spp.) actively modify the biogeochemical and physical properties of soil; however, their influence on nutrient levels in surrounding vegetation is poorly understood. Aside from the reported persistence of elevated available P and K levels in clay-rich soils one year after mound abandonment, the relative stability of nutrient concentrations from one season to the next is largely unknown. Nutrient concentrations were concurrently analysed from ant mounds and undisturbed soils as well as plant samples collected from warm-season turfgrass in a commercial sod production agroecosystem. Initial collection of soil and turfgrass samples coincided with peak annual biomass (September 2006); the second soil sample collection occurred over twelve weeks later during turfgrass dormancy and ant brood minimum (December 2006). Total C, C/N ratios, organic matter (OM), and Zn2+ concentrations as well as pH of ant mound soils were significantly higher than control plot soils; these trends persisted across seasons. Turfgrass harvested from ant mound perimeters in September exhibited elevated N, P, Ca2+, S, Cu2+, Fe2+, and Na+ concentrations. Evaluation of the relative stability of soil parameters across seasons revealed a significant drop in ant nest pH from September to December 2006. Total N of mound soils was distinctively greater than control soil counterparts during September only. Soil P, K+, Ca2+, Mg2+ and S (all macronutrients), as well as Na+ concentrations from ant mound soils were substantially elevated during the late Autumn to Winter transition compared to control soil locations, whereas Fe2+ and Mn2+ levels (both micronutrients) were significantly lower in ant mound soils versus control soil environments. Continuous pedoturbation by imported fire ants as well as seasonal shifts in mound soil chemistry resulting from changes in assimilation/dissimilation among mound biota may influence the site-specific effectiveness of microfaunal pathogens (e.g., Thelohania solenopsae) or parasites (e.g., Orasema spp.) identified as classical biological control agents of non-native Solenopsis spp. Therefore, further study of the intrinsic complexities of soil ecosystem dynamics of imported fire ant mounds across several seasons is warranted.

Designing experiments involves several processes. The first process identifies the experimental units generated by conducting the experiment. The second process is the application of planned treatments to the experimental units. Other processes are the analysis of the experiment and interpretation of results. While traditional experimental small plot designs are useful for investigating many aspects of cotton production, on a large scale, like an entire commercial field, they are difficult to implement because of routine farming operations and topographical variability. As an alternative, by using the capabilities of a variable-rate controller, it is possible to intersect the swath width of the largest farm implement’s boom (or tool bar) along its geo-referenced paths of travel with one or more geo-registered field zones to create experimental units having different shapes and sizes. Defining the experimental units in this manner establishes a site-specific experiment throughout the entire field. Spatial information recovered by Geographic Information System (GIS) processing from these asymmetrical experimental units, when coupled with general linear mixed model methodology, permits the assessment of effects on geo-referenced yield points due to topography, the site-specific and/or traditional farm management practices, and various interactions among them. In this paper, a general methodological approach for analyzing field-sized site-specific experiments is developed and described. An application is demonstrated by analyzing an unreplicated cotton variety trial that included a single site-specific application of a plant growth regulator.

It is known that properties of activated biochars are tightly associated with those of the original feedstock as well as pyrolysis and activation conditions. This study examined two feedstock types, pine wood shavings and chicken litter, to produce biochars at two different pyrolysis temperatures and subsequently activated by steam, acid or base. In order to measure activation efficiency, all materials were characterized for their properties and ability to remediate two well-known heavy metals of concern: copper and arsenic. Base activated biochars were superior in arsenic adsorption, to acid or steam activated samples, but increase in adsorption was not significant to warrant use. For wood biochars, significant increases of surface functionality as related to oxygen bearing groups and surface charge were observed upon acid activation which led to increased copper ion adsorption. However, oxygen bearing functionalities were not sufficient to explain why chicken litter biochars and steam activated biochars appeared to be significantly superior to wood shavings in positively charged metal ion adsorption. For chicken litter, functionality of respective biochars could be related to phosphate containing groups inherited from feedstock composition, favorably positioning this feedstock in metal ion remediation applications.

A field experiment was conducted in 2000, 2001, and 2002 at Stoneville, MS, to determine the effect of spurred anoda interference on yield loss of two cotton cultivars, ‘Delta Pine 5415’ and ‘Pima S-6’, grown under wide (1 m) (WR) and ultra narrow (0.25 m) row (UNR) spacings. The relationship between spurred anoda density and dry weight per plot was linear each year. At a spurred anoda density of 8 m−2, spurred anoda dry weight per plot was 507, 322, and 777 g m−2in 2000, 2001, and 2002, respectively. However, spurred anoda did not interfere with seed cotton yield in 2001, which was probably attributable to the low branch development in that year. Yield losses exceeded 55% at a spurred anoda density of 8 m−2compared with controls in both WR and UNR. The effect of spurred anoda density on boll numbers was nearly identical in 2000 and 2002, regardless of cotton cultivar and row spacing. Boll weights decreased in response to spurred anoda interference. Spurred anoda interference resulted in a decrease in cotton branch dry weight in WR but not in UNR. The yield decrease as a result of spurred anoda interference in WR was due to reduction in boll retention or fruiting sites (predicated on a decrease in branch weight). However, in UNR, the yield decrease was due to plant mortality; the plant density of both cotton cultivars decreased by one plant for each additional spurred anoda, but the yield per plant for surviving plants remained constant. Neither WR nor UNR cotton had significant advantage in response to spurred anoda interference. The decreased boll weight observed in UNR, and the failure to increase boll numbers m−2to compensate for decreased boll weight in UNR compared with WR, may limit its appeal to cotton producers.

When insect population density varies within the same cotton field, estimation of abundance is difficult. Multiple population densities of the same species occur because cotton fields (due to edaphic and environmental effects) are apportioned into various habitats that are colonized at different rates. These various habitats differ temporally in their spatial distributions, exhibiting varying patterns of interspersion, shape and size. Therefore, when sampling multiple population densities without considering the influence of habitat structure, the estimated population mean represents a summary of diverse population distributions having different means and variances. This single estimate of mean abundance can lead to pest management decisions that are incorrect because it may over- or under-estimate pest density in different areas of the field. Delineation of habitat classes is essential in order to make local control decisions. Within large commercial cotton fields, it is too laborious for observers on the ground to map habitat boundaries, but remote sensing can efficiently create geo-referenced, stratified maps of cotton field habitats. By employing these maps, a simple random sampling design and larger sample unit sizes, it is possible to estimate pest abundance in each habitat without large numbers of samples. Estimates of pest abundance by habitat, when supplemented with ecological precepts and consultant/producer experience, provide the basis for spatial approaches to pest control. Using small sample sizes, the integrated sampling methodology maps the spatial abundance of a cotton insect pest across several large cotton fields.

Differential responses to elevated atmospheric CO(2) concentration exhibited by different plant functional types may alter competition for above- and belowground resources in a higher CO(2) world. Because C allocation to roots is often favored over C allocation to shoots in plants grown with CO(2) enrichment, belowground function of forest ecosystems may change significantly. We established an outdoor facility to examine the effects of elevated CO(2) on root dynamics in artificially constructed communities of five early successional forest species: (1) a C(3) evergreen conifer (longleaf pine, Pinus palustris Mill.); (2) a C(4) monocotyledonous bunch grass (wiregrass, Aristida stricta Michx.); (3) a C(3) broadleaf tree (sand post oak, Quercus margaretta); (4) a C(3) perennial herbaceous legume (rattlebox, Crotalaria rotundifolia Walt. ex Gemel); and (5) an herbaceous C(3) dicotyledonous perennial (butterfly weed, Asclepias tuberosa L.). These species are common associates in early successional longleaf pine savannahs throughout the southeastern USA and represent species that differ in life-form, growth habit, physiology, and symbiotic relationships. A combination of minirhizotrons and soil coring was used to examine temporal and spatial rooting dynamics from October 1998 to October 1999. CO(2)-enriched plots exhibited 35% higher standing root crop length, 37% greater root length production per day, and 47% greater root length mortality per day. These variables, however, were enhanced by CO(2) enrichment only at the 10-30 cm depth. Relative root turnover (flux/standing crop) was unchanged by elevated CO(2). Sixteen months after planting, root biomass of pine was 62% higher in elevated compared to ambient CO(2) plots. Conversely, the combined biomass of rattlebox, wiregrass, and butterfly weed was 28% greater in ambient compared to high CO(2) plots. There was no difference in root biomass of oaks after 16 months of exposure to elevated CO(2). Using root and shoot biomass as a metric, longleaf pine realized the greatest and most consistent benefit from exposure to elevated CO(2). This finding suggests that the ability of longleaf pine to compete with sand post oak, a common deciduous tree competitor, and wiregrass, the dominant understory herbaceous species, in regenerating ecosystems may be significantly enhanced by rising atmospheric CO(2) concentrations.

Waxy (short grain), long grain, and parboiled (long grain) rice flours were extruded using three different temperatures and five different water feed rates. The water absorption and water solubility index of the extrudates was 0.67–5.86 and 86.45–10.03%, respectively. The fat absorption index was similar to that of unextruded flours with an average value of 0.96 g/g ± 0.12. Bulk density decreased with an increase in moisture, except waxy rice, which had a quadratic relationship. The viscosity profiles for long grain and parboiled rice were similar. Both initially increased in viscosity (>130 RVU), then decreased to ≈40 RVU. The final viscosity was ≈60 RVU. Waxy rice viscosity remained low ( 0.05) except for long gr...

There are a myriad of carbonaceous precursors that can be used advantageously to produce activated carbons or chars, due to their low cost, availability and intrinsic properties. Because of the nature of the raw material, production of granular activated chars from broiler manure results in a significant ash fraction. This study was conducted to determine the influence of several pre- and post-treatment strategies in various physicochemical and adsorptive properties of the resulting activated chars. Pelletized samples of broiler litter and cake were pyrolyzed at 700 °C for 1 h followed by a 45 min steam activation at 800 °C at different water flow rates from 1 to 5 mL min −1 . For each activation strategy, samples were either water-rinsed or acid-washed and rinsed or used as is (no acid wash/rinse). Activated char’s physicochemical and adsorptive properties towards copper ions were selectively affected by both pre- and post-treatments. Percent ash reduction after either rinsing or acid washing ranged from 1.1 to 15.1% but washed activated chars were still alkaline with pH ranging from 8.4 to 9.1. Acid washing or water rinsing had no significant effect in the ability of the activated char to adsorb copper ions, however it significantly affected surface area, pH, ash content and carbon content. Instead, manure type (litter versus cake) and the activation water flow rate were determining factors in copper ion adsorption which ranged from 38 mg g −1 to 104 mg g −1 of activated char. Moreover, strong positive correlations were found between copper uptake and concentration of certain elements in the activated char such as phosphorous, sulfur, calcium and sodium. Rinsing could suffice as a post treatment strategy for ash reduction since no significant differences in the carbon properties were observed between rinsed and acid wash treatments.

A simulation study was conducted to determine how well SAS PROC GLIMMIX (SAS Institute, Cary, NC), statistical software to fit generalized linear mixed models (GLMMs), performed for a simple GLMM, using its default settings, as a naive user would do. Data were generated from a wide variety of distributions with the same sets of linear predictors, and under several conditions. Then, the data sets were analyzed by using the correct model (the generating model and estimating model were the same) and, subsequently, by misspecifying the estimating model, all using default settings. The data generation model was a randomized complete block design where the model parameters and sample sizes were adjusted to yield 80% power for the F-test on treatment means given a 30 block experiment with blockby-treatment interaction and with additional treatment replications within each block. Convergence rates were low for the exponential and Poisson distributions, even when the generating and estimating models matched. The normal and lognormal distributions converged 100% of the time; convergence rates for other distributions varied. As expected, reducing the number of blocks from 30 to five and increasing replications within blocks to keep total N the same reduced power to 40% or less. Except for the exponential distribution, estimates of treatment means and variance parameters were accurate with only slight biases. Misspecifying the estimating model by omitting the block-by-treatment random effect made F-tests too liberal. Since omitting that term from the model, effectively ignoring a process involved in giving rise to the data, produces symptoms of over-dispersion, several potential remedies were investigated. For all distributions, the historically recommended variance stabilizing transformation was applied, and then the transformed data were fit using a linear mixed model. For one-parameter members of the exponential family an over-dispersion parameter was included in the estimating model. The negative binomial distribution was also examined as the estimating model distribution. None of these remedial steps corrected the over-dispersion problem created by misspecifying the linear predictor, although using a variance stabilizing transformation did improve convergence rates on most distributions investigated.

Imported fire ant colonies were quantified in 1,000-m(2) circular subplots spaced approximately 125 m apart on a sheep and goat farm in Oklahoma. Social form (percent polygyny), mound density, cumulative above-ground mound volume, and average mound volume were subjected to multiple regression analyses to examine trends related to landscape metrics and habitat characteristics. Monogyne populations were spatially autocorrelated, and polygyne mounds tended to be smaller and more numerous. A model incorporating the effects of percent polygyny, canopy cover, and 1-d cumulative incident solar radiation explained 34% of the variation in mound density. Percent polygyny was not significantly related to cumulative mound volume, which provides a better estimate of overall ant biomass. A model incorporating the effects of 1-d cumulative incident solar radiation on the summer solstice, elevation, canopy cover, distance from cisterns, distance from water, and distance from trees explained 42% of the variation in cumulative mound volume. Monogyne mounds in areas that were flat and close to water in low-lying areas were largest. Results indicate that remotely sensed data in combination with publicly available U.S. Geological Survey data may be useful in predicting areas of high and low fire ant abundance at a field scale.

Flight activities of Africanized honey bee ( Apis mellifera L.) drones were compared with those of two color morphs of European drones in Venezuela. European drones departed from colonies 19 ± 2 ( x ± SEM) min earlier, and flight times were more variable than those of Africanized drones. Mean flight time differences decreased as the drones aged and were similar whether drones were flying from Africanized or European colonies. Overlap of their flight distributions was >70%, which suggests that interbreeding of the two types of bees will be substantial under most natural conditions. Black and yellow European drones flew at similar times with similar variances, which precludes the idea that flight time differences are due to body color.

The adoption of cotton producing insecticidal proteins of Bacillus thuringiensis, commonly referred to as Bt cotton, around the world has proven to be beneficial for growers and the environment. The effectiveness of this important genetically-modified crop can be jeopardized by the development of resistance to Bt cotton by pests it is meant to control, with the possibility that this phenomenon could develop in one country and spread to another by means of insect migration. To preserve the effectiveness of this agricultural biotechnology, regulatory agencies have developed plans to mitigate the development of resistance, and research institutions constantly monitor for shifts in Bt-susceptibility in important pests. If Bt-resistance is detected, this finding needs to be corroborated by an independent laboratory according to current regulatory requirements; a process that presents numerous challenges. We investigated the biological activity of Bt-incorporated diet on Helicoverpa virescens L. after it was stored for several days at different temperatures. Diet stored up to nine days at different temperatures (-14 to 27 degrees C) produced the same biological effect on H. virescens as freshly-prepared diet. Elevating the temperature of Bt stock solution to 76 degrees C as compared to 26 degrees C yielded significantly higher reading of apparent Cry1Ac concentration from MVP II, but not enough to elicit a significant biological response when these stock solutions were incorporated into insect artificial diet. These findings are important particularly when the confirmation of resistance is done at a distant location, such as Mexico, or when diet is shared between laboratories, and must be stored for later use, as in the case of international collaboration.

Differences in flight activity and in the percentages of pollen foragers between commercially managed honey bees, Apis mellifera L. (Hymenoptera: Apidae), of two stocks (USDA–ARS Russian, n = 41 colonies; and Italian, n = 43 colonies) were evaluated in an almond, Prunus dulcis (Miller) D. A. Webb, orchard in Kern Co., CA, during February and March 2002. Flight activity was measured by taking 1-min counts of bees exiting colonies on each of 9 d. Flight activity was best predicted with a model containing the effects of colony size (populations of adult bees and sealed brood), temperature, time of day, the interaction of adult bee population with temperature, and the interaction of adult bee population with time of day. Flight increased linearly with adult bee and brood population, had a quadratic relationship with temperature (increasing, but less so at higher temperatures), and had a quadratic relationship with time of day (decreasing, but less so at later times). Larger colonies had more response to changing temperatures and less response to different times of day than small colonies. Bee type had no direct influence on flight activity at any given colony size, temperature, or time of observation or when evaluated using a reduced data set retaining 34 Italian colonies and 32 Russian colonies whose mean sizes were equal. Overall, however, Russian colonies were less populous by about one-fourth and so fielded on average 71% of the foragers that Italian colonies did. Pollen collection was measured by capturing returning foragers on 4 d. The percentages of foragers with pollen were not different for the bee types.

Nous avons etudie l'influence du nourrissement au sirop de sucre donne avant la miellee sur des colonies d'abeilles africanisees et d'abeilles europeennes au Venezuela. Deux ruchers, distants de 2 km et comprenant 20 colonies chacun, ont ete crees. Dix colonies africanisees et 10 colonies europeennes ont ete affectees a chacun des ruchers dans un ordre aleatoire. Dans chaque rucher, 5 colonies de chaque type geographique, prises dans un ordre aleatoire, ont recu soit un litre de sirop de sucre a 50% (vol/vol) par ruche 2 fois par semaine, soit 3 l de sirop par ruche 2 fois par semaine