Anna M. McClung

National Research Center (CO, USA), Boulder, Colorado, United States

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Publications (111)188.87 Total impact

  • Ming-Hsuan Chen · Anna M McClung
    Cereal Chemistry 03/2015; DOI:10.1094/CCHEM-11-14-0240-R · 1.06 Impact Factor
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    ABSTRACT: An understanding of cultivar effects on field greenhouse gas (GHG) emissions in rice ( L.) systems is needed to improve the accuracy of predictive models used for estimating GHG emissions and to evaluate the GHG mitigation potential of different cultivars. We compared CH and NO emissions, global warming potential (GWP = NO + CH), yield-scaled GWP (GWP = GWP Mg grain), and plant growth characteristics of eight cultivars within four study sites in California and Arkansas. Nitrous oxide emissions were negligible (<10% of GWP) and were not different among cultivars. Seasonal CH emissions differed between cultivars by a factor of 2.1 and 1.4 at one California and one Arkansas site, respectively. Plant growth characteristics were generally not correlated with seasonal CH emissions; however, the strongest correlations were observed for shoot and total plant (root + shoot) biomass at heading ( = 0.60) at one California site and for grain at maturity ( = -0.95) at one Arkansas site. Although differences in GWP and GWP were observed, there were inconsistencies across sites, indicating the importance of the genotype × environment interaction. Overall, the cultivars with the lowest CH emissions, GWP, and GWP at the California and Arkansas sites were the lowest and highest yielding, respectively. These findings highlight the potential for breeding high-yielding cultivars with low GWP, the ideal scenario to achieve low GWP, but environmental conditions must also be considered. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.
    Journal of Environmental Quality 01/2015; 44(1):103-114. DOI:10.2134/jeq2014.07.0286 · 2.35 Impact Factor
  • Byungrok Min · Anna McClung · Ming-Hsuan Chen
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    ABSTRACT: The impacts of parboiling and wet-cooking, alone and in combination, on the concentrations of lipophilic antioxidants (vitamin E and γ-oryzanol), soluble (including proanthocyanidins and anthocyanins) and cell wall-bound phenolics, and antioxidant capacities in whole grain rice from six cultivars having different bran colours were investigated. Parboiling rough and brown rice increased the concentrations of lipophilic antioxidants in whole grain rice but decreased the concentrations of total phenolics and antioxidant capacities found in the soluble fraction. After hydrothermal processing of purple bran rice, the retention of extractable anthocyanins was low, but was high for simple phenolics. For proanthocyanidins found in red bran rice, the extractable oligomers with a degree of polymerization (DP) less than 4, increased up to 6-fold; while for oligomers with DP ⩾ 4 and polymers, there was a significant decrease that was positively correlated with the DP and the temperature of the processing methods. The presence of hulls helped to retain water-soluble antioxidants during parboiling.
    Food Chemistry 09/2014; 159:106–115. DOI:10.1016/j.foodchem.2014.02.164 · 3.39 Impact Factor
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    ABSTRACT: To identify the genes responsible for yield related traits, and heterosis, massively parallel signature sequencing (MPSS) libraries were constructed from leaves, roots and meristem tissues from the two parents, 'Nipponbare' and '93-11', and their F1 hybrid. From the MPSS libraries, 1-3 million signatures were obtained. Using cluster analysis, commonly and specifically expressed genes in the parents and their F1 hybrid were identified. To understand heterosis in the F1 hybrid, the differentially expressed genes in the F1 hybrid were mapped to yield related quantitative trait loci (QTL) regions using a linkage map constructed from 131 polymorphic simple sequence repeat markers with 266 recombinant inbred lines derived from a cross between Nipponbare and 93-11. QTLs were identified for yield related traits including days to heading, plant height, plant type, number of tillers, main panicle length, number of primary branches per main panicle, number of kernels per main panicle, total kernel weight per main panicle, 1000 grain weight and total grain yield per plant. Seventy one QTLs for these traits were mapped, of which 3 QTLs were novel. Many highly expressed chromatin-related genes in the F1 hybrid encoding histone demethylases, histone deacetylases, argonaute-like proteins and polycomb proteins were located in these yield QTL regions. A total of 336 highly expressed transcription factor (TF) genes belonging to 50 TF families were identified in the yield QTL intervals. These findings provide the starting genomic materials to elucidate the molecular basis of yield related traits and heterosis in rice.
    PLoS ONE 04/2014; 9(4):e95178. DOI:10.1371/journal.pone.0095178 · 3.23 Impact Factor
  • Journal of Plant Registrations 01/2014; 8(1):109. DOI:10.3198/jpr2013.03.0013crmp · 0.48 Impact Factor
  • Rolfe Bryant · K. Yeater · A. McClung
    12/2013; DOI:10.1094/CPLEX-2013-1226-17W
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    ABSTRACT: Rice bran chemical profiles differ across rice varieties and have not yet been analysed for differential chemopreventive bioactivity. A diverse panel of seven rice bran varieties was analysed for growth inhibition of human colorectal cancer (CRC) cells. Inhibition varied from 0% to 99%, depending on the variety of bran used. Across varieties, total lipid content ranged 5-16%, individual fatty acids had 1.4- to 1.9-fold differences, vitamin E isoforms (α-, γ-, δ-tocotrienols, and tocopherols) showed 1.3- to 15.2-fold differences, and differences in γ-oryzanol and total phenolics ranged between 100-275ng/mg and 57-146ngGAE/mg, respectively. Spearman correlation analysis was used to identify bioactive compounds implicated in CRC cell growth inhibitory activity. Total phenolics and γ-tocotrienol were positively correlated with reduced CRC cell growth (p<0.05). Stoichiometric variation in rice bran components and differential effects on CRC viability merit further evaluation elucidate their role in dietary CRC chemoprevention.
    Food Chemistry 11/2013; 141(2):1545-52. DOI:10.1016/j.foodchem.2013.04.020 · 3.39 Impact Factor
  • Ehsan Shakiba · A. McClung · S. McCouch · G. Eizenga
    7th International Rice Genetic Symposium. Manila, the Philippines; 11/2013
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    ABSTRACT: Drill seeded rice (Oryza sativa L.) is the dominant rice cultivation practice in the United States. Although drill seeded systems can lead to significant CH 4 and N 2 O emissions due to anaerobic and aerobic soil conditions, the relationship between high-yielding management practices, particularly fertilizer N management, and total global warming potential (GWP) remains unclear. We conducted three field experiments in California and Arkansas to test the hypothesis that by optimizing grain yield through N management, the lowest yield-scaled global warming potential (GWP Y = GWP Mg -1 grain) is achieved. Each growing season, urea was applied at rates ranging from 0 to 224 kg N ha -1 before the permanent flood. Emissions of CH 4 and N 2 O were measured daily to weekly during growing seasons and fallow periods. Annual CH 4 emissions ranged from 9.3 to 193 kg CH 4 –C ha -1 yr -1 across sites, and annual N 2 O emissions averaged 1.3 kg N 2 O–N ha -1 yr -1 . Relative to N 2 O emissions, CH 4 dominated growing season (82%) and annual (68%) GWP. The impacts of fertilizer N rates on GHG fluxes were confined to the growing season, with increasing N rate having little effect on CH 4 emissions but contributing to greater N 2 O emissions during nonflooded periods. The fallow period contributed between 7 and 39% of annual GWP across sites years. This finding illustrates the need to include fallow period measurements in annual emissions estimates. Growing season GWP Y ranged from 130 to 686 kg CO 2 eq Mg -1
    Journal of Environmental Quality 11/2013; 42:1623-1634. DOI:10.2134/jeq2013.05.0167 · 2.35 Impact Factor
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    ABSTRACT: The grain quality of rice has recently attracted a lot of attention around the world, including Africa. Rice germplasm in African gene banks has not been adequately characterized for its cooking and eating qualities which are mainly controlled by starch physicochemical properties. The aim of this study was to characterize two groups of rice germplasm from Africa and the U.S. for starch properties including gelatinization temperature (GT), apparent amylose content (AAC), and paste viscosity (RVA), and to determine molecular marker associations with these traits. Wide diversity was found for all traits studied. Variation in these traits was significantly associated with molecular markers for the alk and waxy genes which encodes soluble SS II (SSIIa) and granule bound synthase (GBSS) enzymes, respectively. Based on four previously reported waxy SNP haplotypes, 93.1 and 75.9% of the variation in AAC was explained for the U.S. and African germplasm, respectively. The classification of the genotypes by their SNP haplotypes helped to clarify the relationship between AAC and peak viscosity. The characterization of individual lines using physicochemical properties and functional markers, and the determination of marker-trait associations will facilitate the breeding of rice for grain quality in Africa and elsewhere.
    Starch - Starke 11/2013; 65(11-12). DOI:10.1002/star.201300058 · 1.40 Impact Factor
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    ABSTRACT: Whole grain rice is nutrient dense because of the intact bran layer. The literature indicates that there is genetic variability for compounds in the bran layer of whole grain rice with some compounds in high concentrations in varieties with pigmented bran. The purpose of this study was to compare factors that impact sensory characteristics between different classes of rice bran color. Ten varieties, two from each of five bran colors (white, light brown, brown, red, and purple), were evaluated for descriptive flavor and texture, physical characteristics, gelatinization temperature, apparent amylose content, and polyphenols. Rice that has red or purple pigmented bran has higher contents of phenols and flavonoids, and these varieties were strongly correlated with some flavor attributes. The bran/hay/straw attribute correlated with bran weight and bran thickness, and sweet taste negatively correlated with amylose content. The texture attribute of hardness was significantly different among bran colors, and a 64% variance can be explained by kernel density and bran thickness. Physical traits of kernel width, kernel thickness, and bran weight can explain 68.7% of cook time variance. This report advances our understanding of contributing factors to the flavor and texture attributes of the whole grain rice with diverse bran color.
    Cereal Chemistry 11/2013; 90(6):521-528. DOI:10.1094/CCHEM-10-12-0126-R · 1.06 Impact Factor
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    ABSTRACT: Protein is the second most abundant constituent in the rice grain next to starch. Association analysis for protein concentration in brown rice was performed using a "mini-core" collection, which represents the germplasm diversity found in the USDA rice world collection. Protein concentration was determined in replicated trials conducted in two southern U. S. locations, and association mapping was performed by using 157 genomewide DNA markers. Protein concentration ranged from 5.4 to 11.9% among the 202 accessions. Protein variation owing to accession and accession x location interaction were highly significant. Ample variation was seen within each subpopulation by ancestry, as well as within the 14 geographic regions where the accessions originated. Accessions from Eastern Europe had the highest level of protein. Ten markers on eight chromosomes were significantly associated with protein concentration. Five of these markers occurred near known protein precursor genes or quantitative trait loci, and the other five markers were novel for the association with protein concentration in rice. The germplasm and genetic markers identified in this study will assist breeders in developing cultivars tailored for applications requiring specific protein concentration in the rice grain. The research results contribute to the potential discovery of novel rice storage protein pathways in the endosperm.
    Cereal Chemistry 09/2013; 90(5):445-452. DOI:10.1094/CCHEM-09-12-0122-R · 1.06 Impact Factor
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    ABSTRACT: A set of introgression lines (ILs) containing chromosomal segments from O. rufipogon (IRGC 105491), a wild relative of O. sativa, in the genetic background of an elite US variety, cv. Jefferson, was developed to confirm the performance of six yield-enhancing quantitative trait loci (QTL). Fifty BC3F3 ILs containing homozygous O. rufipogon introgressions at each of the target QTL regions, and as few background introgressions as possible, were selected for evaluation of yield and 14 yield-related traits in field studies conducted over 2 years at four locations in the southern USA. Performance of the IL families was compared with three commercial inbreds and one hybrid variety. IL families carrying introgressions from the low-yielding wild parent at the QTL yld2.1 and yld6.1 yielded 27.7 and 26.1 % more than Jefferson, respectively. IL yld2A, which possesses yld2.1, also performed well under alternate wetting and drying conditions in two field locations. After the first year of field trials, 10 of the top-performing BC3F4 families, representing five of the QTL targets, were genotyped with an Illumina 1,536 assay to define the size and location of the wild introgressions. BC3F4 families with the fewest background introgressions were backcrossed to Jefferson and selfed. The resulting BC4F2 families were screened with targeted single nucleotide polymorphism assays to identify individuals carrying homozygous introgressions across the target QTL. Twelve ILs, representing each of the six QTL targets, have been submitted to the Genetic Stocks Oryza Collection for studies on transgressive variation and as interspecific pre-breeding lines.
    Molecular Breeding 06/2013; 32(1). DOI:10.1007/s11032-013-9855-7 · 2.28 Impact Factor
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    ABSTRACT: Vitamin C (l-ascorbic acid) is a key antioxidant for both plants and animals. In plants, ascorbate is involved in several key physiological processes including photosynthesis, cell expansion and division, growth, flowering, and senescence. In addition, ascorbate is an enzyme cofactor and a regulator of gene expression. During exposure to abiotic stresses, ascorbate counteracts excessive reactive oxygen species within the cell and protects key molecules, including lipids, proteins, and nucleic acids, from irreversible damage. In this study we focus on understanding how ascorbate levels are controlled in rice (Oryza sativa) during plant development and in response to light intensity and photoperiod. Our results indicate that in rice ascorbate metabolism follows a different pattern compared to other species. In the rice accessions we analyzed, total foliar ascorbate content increases during development and peaks at the vegetative 2-4 and the reproductive 4 stages, whereas other research has shown that in Arabidopsis thaliana and other dicots, ascorbate content declines with plant age. The pattern in rice does not seem to change when plants were grown under increasing light intensity: 150, 400 or 1200-1500 μmol m-2 s-1. We observed little diurnal variation in AsA content in rice and did not see a steady decline during the dark period as has been reported in other species such as Arabidopsis and tomato. The total foliar ascorbate content of twenty-three rice accessions from four major rice subgroups was compared. These genotypes differed as much as eight-fold in ascorbate content at the V2 stage indicating the potential to enhance vitamin C levels in genotypes of global interest via breeding approaches.
    Plant Physiology and Biochemistry 02/2013; 66C:41-46. DOI:10.1016/j.plaphy.2013.01.016 · 2.35 Impact Factor
  • G. Liu · Y. Jia · A. McClung · J. H. Oard · F. N. Lee · J. C. Correll
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    ABSTRACT: Liu, G., Jia, Y., McClung, A., Gard, J. H., Lee, F. N., and Correll, J. C. 2013. Confirming QTLs and finding additional loci responsible for resistance to rice sheath blight disease. Plant Dis. 97:113-117. Rice sheath blight disease, caused by Rhizoctonia solani AG1-1A, is one of the most destructive rice diseases worldwide. Utilization of host resistance is the most economical and environmentally sound strategy in managing sheath blight (ShB). Ten ShB quantitative trait loci (QTLs) were previously mapped in a Lemont x Jasmine 85 recombinant inbred line (LJRIL) population using greenhouse inoculation methods at an early vegetative stage. However, confirmation of ShB-resistant QTLs under field conditions is critical for their utilization in marker-assisted selection (MAS) for improving ShB resistance in new cultivars. In the present study, we evaluated ShB resistance using 216 LIRILs under field conditions in Arkansas. Texas, and Louisiana during 2008 and 2009. We confirmed the presence of the major ShB-QTL qShB9-2 based on the field data and also identified one new ShB-QTL between markers RM221 and RM112 on chromosome 2 across all three locations. Based on the field verification of ShB evaluations, the microchamber and mist-chamber assays were simple, effective, and reliable methods to identify major ShB-QTLs like qShB9-2 in the greenhouse at early vegetative stages. The markers RM215 and RM245 were found to be closely linked to aShB9-2 in greenhouse and field assays, indicating that they will be useful for improving ShB resistance in rice breeding programs using MAS.
    Plant Disease 01/2013; 97(1):113-117. DOI:10.1094/PDIS-05-12-0466-RE · 3.02 Impact Factor
  • R. J. Bryant · A. M. McClung · C. Grimm
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    ABSTRACT: Because of the high demand for aromatic rice cultivars that command a premium, it is important to have efficient methods for determining 2-acetyl-1-pyrroline (2-AP), the aromatic compound found in rice, that can be used in breeding efforts and to detect aromatic/non-aromatic blended rice in the marketplace. Solid-phase microextraction (SPME) in conjunction with GC/MS was used to distinguish non-aromatic rice (Oryza sativa, L.) kernels from aromatic rice kernels. In this method, single kernels along with 10 μl of 0.1 ng μl−1 2,4,6-Trimethylpyridine were placed in sealed vials and heated to 80 °C for 18 min. During the heating stage volatile compounds, which include 2-AP, were adsorbed onto a SPME fiber. Volatiles were desorbed from the fiber and separated using gas chromatography. 2-AP was quantitated by mass spectrometry using the 111, 83 and 68 m/z ions. The method detected 2-AP in milled rice and brown rice; however, its detection in paddy rice was less successful. In a mixture of aromatic and non-aromatic rice, the aromatic rice kernels were differentiated from the non-aromatic rice kernels using the described method. Therefore, this method can be used to identify segregating from non-segregating progeny during early generations in an aromatic rice breeding program when quantities of seed are very limited and can determine if aromatic rice has been adulterated with non-aromatic rice either through inadvertent mixtures, outcrosses or prepared blends.
    Sensing and Instrumentation for Food Quality and Safety 12/2012; 5(5):147-154. DOI:10.1007/s11694-012-9121-4
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    ABSTRACT: To study the polyphenols in whole grain rice varying in bran colour, the total phenolics, flavonoids and antioxidant capacities of the solvent-extractable (Free) and cell-wall bound (Bound) fractions and the profiles of proanthocyanidins and anthocyanins were determined. Red and purple bran rices had significantly higher total (sum of Free- and Bound-) phenolic (PC) and flavonoid (FC) concentrations and antioxidant capacities than light-coloured bran rice or other cereals (P < 0.05), due to their higher concentrations of proanthocyanidins and anthocyanins, respectively. The concentrations of the Bound-PC and FC accounted for approximately half of the total PC and FC in the light-coloured bran rice, but were lower than those in purple and red bran rice (P < 0.05). High correlations were found between the concentrations of total phenolics and the three antioxidant capacity assays except for those in the bound fraction when related to iron chelating capacity. The concentrations of proanthocyanidins in red bran rice was 1.27 mg/g and its composition was 6.5%, 33.5%, 30.6% and 29.4% of 1–3, 4–6, 7–10 mers, and polymer (>10 mers), respectively. Cyanidin-3-glucoside was the predominant anthocyanin and peonidin-3-glucoside was the second highest; the profiles varied between purple bran cultivars. Whole grain rice differing in bran colour contained unique polyphenol subgroups, which have been proposed to positively impact human health.
    Food Chemistry 08/2012; 133(3):715–722. DOI:10.1016/j.foodchem.2012.01.079 · 3.39 Impact Factor
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    ABSTRACT: Multiplexed single nucleotide polymorphism (SNP) markers have the potential to increase the speed and cost-effectiveness of genotyping, provided that an optimal SNP density is used for each application. To test the efficiency of multiplexed SNP genotyping for diversity, mapping and breeding applications in rice (Oryza sativa L.), we designed seven GoldenGate VeraCode oligo pool assay (OPA) sets for the Illumina BeadXpress Reader. Validated markers from existing 1536 Illumina SNPs and 44 K Affymetrix SNP chips developed at Cornell University were used to select subsets of informative SNPs for different germplasm groups with even distribution across the genome. A 96-plex OPA was developed for quality control purposes and for assigning a sample into one of the five O. sativa population subgroups. Six 384-plex OPAs were designed for genetic diversity analysis, DNA fingerprinting, and to have evenly-spaced polymorphic markers for quantitative trait locus (QTL) mapping and background selection for crosses between different germplasm pools in rice: Indica/Indica, Indica/Japonica, Japonica/Japonica, Indica/O. rufipogon, and Japonica/O. rufipogon. After testing on a diverse set of rice varieties, two of the SNP sets were re-designed by replacing poor-performing SNPs. Pilot studies were successfully performed for diversity analysis, QTL mapping, marker-assisted backcrossing, and developing specialized genetic stocks, demonstrating that 384-plex SNP genotyping on the BeadXpress platform is a robust and efficient method for marker genotyping in rice.
    Molecular Breeding 04/2012; 29(4):875-886. DOI:10.1007/s11032-011-9663-x · 2.28 Impact Factor
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    ABSTRACT: Recognition of the health benefits of whole-grain and pigmented bran rice has resulted in their increased consumption. Bran contributes fiber, minerals, vitamins and an array of phytonutrients to the diet. Understanding flavor differences arising from bran pigmentation helps consumers choose the best rice for their use. Ten panelists trained in descriptive analysis developed 25 descriptors to describe whole-grain rice flavor and evaluated the flavor of 22 rice samples with white, light-brown, dark-brown, red and black bran. Brown rice had more intense grainy/starchy, cooked cereal and corn/popcorn/buttery flavors. Black rice was higher in oily, darkberry, medicinal and smoky/burnt flavors. Red rice had greater intensities for beany, animal/wet dog and earthy flavors. The darker cultivars tend to have more bitter taste and astringent mouthfeel. This lexicon enhances the understanding of flavors associated with rice bran color. Whole-grain rice is unpolished or unmilled rice with the bran layers retained. The bran layer has many nutrients that are removed during polishing (milling). Because of the health benefits of keeping the bran layer intact, whole-grain rice has experienced an increase in demand worldwide. Milled-rice flavor has been characterized, but whole-grain rice has a different flavor profile due to the bran. This new whole-grain rice flavor lexicon describes the flavor attributes and differences between bran color and types of whole-grain rice.
    Journal of Sensory Studies 04/2012; 27(2). DOI:10.1111/j.1745-459X.2011.00368.x · 2.58 Impact Factor
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    ABSTRACT: Sheath blight (ShB) caused by the soil-borne pathogen Rhizoctonia solani is one of the most devastating diseases in rice world-wide. Global attention has focused on examining individual mapping populations for quantitative trait loci (QTLs) for ShB resistance, but to date no study has taken advantage of association mapping to examine hundreds of lines for potentially novel QTLs. Our objective was to identify ShB QTLs via association mapping in rice using 217 sub-core entries from the USDA rice core collection, which were phenotyped with a micro-chamber screening method and genotyped with 155 genome-wide markers. Structure analysis divided the mapping panel into five groups, and model comparison revealed that PCA5 with genomic control was the best model for association mapping of ShB. Ten marker loci on seven chromosomes were significantly associated with response to the ShB pathogen. Among multiple alleles in each identified loci, the allele contributing the greatest effect to ShB resistance was named the putative resistant allele. Among 217 entries, entry GSOR 310389 contained the most putative resistant alleles, eight out of ten. The number of putative resistant alleles presented in an entry was highly and significantly correlated with the decrease of ShB rating (r = -0.535) or the increase of ShB resistance. Majority of the resistant entries that contained a large number of the putative resistant alleles belonged to indica, which is consistent with a general observation that most ShB resistant accessions are of indica origin. These findings demonstrate the potential to improve breeding efficiency by using marker-assisted selection to pyramid putative resistant alleles from various loci in a cultivar for enhanced ShB resistance in rice.
    PLoS ONE 03/2012; 7(3):e32703. DOI:10.1371/journal.pone.0032703 · 3.23 Impact Factor

Publication Stats

3k Citations
188.87 Total Impact Points


  • 2013
    • National Research Center (CO, USA)
      Boulder, Colorado, United States
  • 2010
    • Crop Science Society of America
      Madison, Wisconsin, United States
  • 2009
    • University of Arkansas
      Fayetteville, Arkansas, United States
  • 2007
    • University of California, Davis
      Davis, California, United States