bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbohydrate and Nitrogen Reserves Relative to Regrowth Dynamics of ‘Tifton 85’ Bermudagrass as Affected by Nitrogen Fertilization
Authors: Alderman P. D. , Boote K. J. , Sollenberger L. E. , Coleman S. W. 
Published: June 2011

ABSTRACTCarbohydrate and N reserves are important for perennial grass regrowth after defoliation. The objective of this study was to quantify the effects of N fertilization on dynamics of reserve accumulation and utilization for regrowth of a C4 perennial grass. A field study was conducted at Gainesville, FL, on established ‘Tifton 85’ bermudagrass (Cynodon spp.) in 2006 and 2007. Treatments were N rates of 0, 45, 90, and 135 kg N ha−1 regrowth period−1. Total nonstructural carbohydrate (TNC) and N concentrations, leaf area index (LAI), and canopy carbon exchange rate (CER) were measured weekly during 28‐d regrowth periods. Stem and rhizome TNC concentrations decreased with increasing N rate, ranging from 20 to 80 mg g−1 for stem and 45 to 145 mg g−1 for rhizome, and followed quadratic time trends, with minima between 7 and 14 d of regrowth, suggesting reserve utilization up to 2 wk after defoliation. Leaf, stem, rhizome, and root N concentrations increased with N rate. Leaf and stem N concentrations followed quadratic time trends, with maxima between 7 and 14 d of regrowth, and ranged from 15 to 50 mg g−1 for leaf and 10 to 40 mg g−1 for stem. Rhizome N concentrations were constant throughout regrowth. Canopy CER and LAI followed logistic time trends within each 28‐d regrowth period, with upper asymptotes raised by increased N rate. Nitrogen fertilization increased TNC reserve utilization, LAI, and canopy CER, thereby increasing shoot regrowth at rates up to 90 kg N ha−1 period−1.
A Ds Insertional Mutant of a Barley miR172 Gene Results in Indeterminate Spikelet Development
Authors: Brown Ryan H. , Bregitzer Phil 
Published: June 2011

ABSTRACTA simple, polymerase chain reaction (PCR) and agarose gel‐based system was used to efficiently detect barley (Hordeum vulgare L.) lines with novel transpositions of a modified maize (Zea mays L.) Ds element. One line contained a Ds insertion in a gene critical to barley spike development which appears to be a regulatory component of the ABC model of floral development. This model, elucidated based on studies of dicots, is widely conserved and function of key genes–such as AP2–have been demonstrated in monocots such as rice (Oryza sativa L.) and maize, but significant differences in orthologous gene function exist. This report describes the generation of a Ds‐insertional mutant of a putative barley ortholog of miR172. The miR172 family of microRNAs (miRNAs) includes a member shown to control the expression of AP2 and AP2‐like orthologs during floral development. The Ds‐miR172 mutant contains a 3.6 kb insertion in the mature miRNA sequence, thus abolishing function, and the associated floral abnormalities are consistent with the failure to properly regulate the barley AP2 ortholog. Ds‐miR172 mutants show abnormal spikelet development, including the conversion of glumes to partially developed florets in apical regions of spikes. Basal regions of the spike show an abnormal branching phenotype resulting from indeterminate spikelet meristem development, with each branch consisting of multiple, abnormal spikelets and other floral organs in place of a single spikelet. This phenotype is similar to ts4 in maize, the only other known mutation affecting a miR172 ortholog.
Identification of Tobacco Haploids on the Basis of Transgenic Overexpression of PAP1 from Arabidopsis thaliana
Authors: Lewis Ramsey S. , Rose Cara 
Published: June 2011

ABSTRACTHaploid plants have utility in plant breeding for several purposes. In tobacco (Nicotiana tabacum L.) gynogenic haploids can be produced from seed due to parthenogenesis. For practical use, a system is needed to identify infrequent haploid plants at the seed or seedling stage. Interspecific hybridization with N. africana is presently used to isolate gynogenic tobacco haploids because a suitable dominant seedling marker does not currently exist for N. tabacum. Here we investigated the utility of a purple seedling trait conferred by overexpression of the Arabidopsis gene, PAP1, to identify gynogenic haploids produced from seed. Two tobacco cultivars were crossed as females with a genetic stock homozygous at two 35S:PAP1 transgene loci. Gynogenic haploids were recognized as green seedlings among purple F1 hybrid seedlings. The average frequency of gynogenic haploidy using this system was f = 0.00027. For comparison, the same cultivars were also hybridized as females with N. africana. The average frequency of gynogenic haploidy using this system was approximately seven times higher than that observed for the 35S:PAP1 system. Having a dominant seedling marker for N. tabacum may permit development of genetic stocks that contribute to an increased predisposition for haploid formation via parthenogenesis. In addition, the 35S:PAP1 genetic marker may have utility for identifying androgenic haploids from seed for the purpose of rapidly generating alloplasmic lines of tobacco.
Rumen‐Degradable Protein in Roll‐Conditioned or Macerated Legume Hays and Silages Estimated by In Situ Kinetics vs. Alternative Methods
Authors: Grabber J. H. , Coblentz W. K. , Broderick G. A. 
Published: June 2011

ABSTRACTAlternatives to the in situ method for estimating rumen‐degradable protein (RDP) in diverse forage legumes should be validated. In this study, RDP in roll‐conditioned or macerated silages and hays of Medicago, Lotus, and Trifolium species with differing polyphenol compositions were estimated from in situ degradation kinetics, a rumen microbial inhibitor in vitro assay, a 10‐h in situ incubation, the Cornell Net Carbohydrate and Protein System, and a 16‐h in vitro Streptomyces griseus protease digestion. Forage species, conditioning, and conservation methods influenced RDP estimates. In situ kinetic RDP could be ranked or in some cases accurately predicted by other RDP methods, but the protease method performed poorly for macerated forages.
Doubled Haploids in Tropical Maize: I. Effects of Inducers and Source Germplasm on in vivo Haploid Induction Rates
Authors: Prigge Vanessa , Sánchez Ciro , Dhillon Baldev S. , Schipprack Wolfgang , Araus José Luis , Bänziger Marianne , Melchinger Albrecht E. 
Published: June 2011

ABSTRACTThe adoption of the doubled haploid (DH) technology in tropical maize (Zea mays L.) breeding programs is lagging behind that of temperate programs due to a lack of tropical haploid inducers and reliable information on the performance of temperate inducers under nontemperate conditions. The objective of this study was to determine the in vivo haploid induction ability of three temperate inducers crossed to a diverse set of tropical maize source germplasm under tropical conditions. Three experiments were conducted employing inducers as male parents to pollinate 120 source germplasm in three environments in Mexico. Haploid induction rates (HIR) obtained under field conditions were determined with two different haploid identification systems. Highly significant genotypic differences were detected among inducers and source germplasm for HIR but no interactions were observed between the two factors. Mean HIR under tropical conditions were similar to those reported for evaluations under temperate conditions indicating that temperate inducers can be employed for initiation of DH breeding programs in the tropics. Misclassification of diploids as haploids resulted in inflated HIR, particularly in highly variable source germplasm such as landraces or when expression of the identification marker was weak. We conclude that induction of haploidy is not a limiting factor for DH line production in tropical maize, but there is a need for the development of well‐adapted tropical inducers.
Elevated Growing Degree Days Influence Transition Stage Timing During Cotton Fiber Development Resulting in Increased Fiber‐Bundle Strength
Authors: Hinchliffe Doug J. , Meredith William R. , Delhom Christopher D. , Thibodeaux Devron P. , Fang David D. 
Published: June 2011

ABSTRACTGrowing degree days required for cotton (Gossypium hirsutum L.) growth and development were recorded for four growing seasons and compared with fiber‐quality measurements and gene expression data indicative of different stages of fiber development. Fiber‐bundle strength differences between the Upland cotton near‐isogenic lines MD 52ne and MD 90ne were observed using immature and mature fibers collected at different time points of development stages. Previously characterized fiber‐bundle‐strength differences between the near‐isogenic lines, known as a result of early entrance into the transition stage of fiber development, were present as early as 20 d postanthesis and persisted to boll opening and fiber maturity. The onset of transition stage was correlated with the accumulated degree day heat units from the day of anthesis in both cotton lines in all seasons. Fiber‐quality measurements obtained over multiple growing seasons indicated that an earlier entrance into the transition stage of fiber development resulted in increased fiber‐bundle strength. These data suggest that the identification of genes associated with early entrance into the transition stage can be used to temporally manipulate fiber development and improve fiber quality.
Estimation of Genetic Parameters for Biomass Yield in Lowland Switchgrass (Panicum virgatum L.)
Authors: Bhandari H. S. , Saha M. C. , Fasoula V. A. , Bouton J. H. 
Published: June 2011

ABSTRACTSwitchgrass (Panicum virgatum L.) is an important herbaceous species for use in biofuel production. Genetic improvement of biomass yield and related traits of switchgrass will help ensure efficient feedstock production. To understand the genetics of biomass yield and related traits, 46 full‐sib families, including 30 derived using a nested design, were evaluated during 2008 and 2009 in spaced‐plant nurseries at Ardmore and Burneyville, OK, following a honeycomb design. Parental genotypes were evaluated adjacent to the family nurseries at Ardmore. Mean biomass yields of full‐sib families ranged from 1.32 to 2.18 kg plant−1. One family outperformed checks, while 16 other families performed as well as checks. Results showed a preponderance of additive genes in controlling biomass yield, tillering ability, and spring regrowth. Narrow‐sense heritabilities for biomass yield were estimated to be 0.17, 0.14, and 0.24, based on half‐sib families, full‐sib/half‐sib families, and midparent–progeny regression, respectively. Tillering abilities showed similar heritability estimates (0.20–0.24) using either method. For heading and flowering and spring regrowth, the heritability estimates were larger using midparent–progeny regression than using variation among half‐sib or full‐sib/half‐sib families. Heritability for plant height and stem thickness were larger when estimated using half‐sib families than full‐sib/half‐sib families, while the reverse held true for plant spread. Rigorous family evaluation and use of tillering ability, plant height, and stem thickness could be helpful in improving biomass yield in switchgrass.
Comparison of Conventional, Modified Single Seed Descent, and Doubled Haploid Breeding Methods for Maize Inbred Line Development Using Germplasm Enhancement of Maize Breeding Crosses
Authors: Jumbo McDonald , Weldekidan Teclemariam , Holland James B. , Hawk James A. 
Published: June 2011

ABSTRACTBreeding crosses from the Germplasm Enhancement of Maize (GEM) project between exotic accessions and elite Corn Belt Dent inbreds provide a unique opportunity for broadening the genetic base of the U.S. maize (Zea mays L.) crop by incorporating favorable exotic alleles in elite genetic backgrounds. Genetic gains in the GEM program could be enhanced by identifying more efficient breeding procedures for this purpose. We compared four breeding methods, conventional Germplasm Enhancement of Maize (CG), conventional mass (CM), modified single seed descent (MSSD), and doubled haploid (DH) methods, for their relative capacity to produce superior maize inbred lines and hybrids from three GEM breeding crosses: (ANTIG01 × N16) × DE4, (AR16035 × S02) × S09, and (DKXL212 × S09) × S43b. Testcross evaluations of 50 selected lines from each combination of cross and breeding method were conducted across multiple environments, generally revealing no differences among breeding methods. The MSSD and CM methods had higher proportions of the top 10 lines for grain yield and yield:moisture ratio in the second year testcross reevaluations of about the top 28% of lines. Hybrids from MSSD lines tended to have higher grain moisture, but MSSD hybrids with high yield:moisture ratio could still be identified. The MSSD method may be an effective and efficient alternative to both pedigree and DH methods for developing high performing lines from the GEM breeding crosses as it requires relatively fewer resources.
Divot Resistance Varies among Bermudagrass and Zoysiagrass Cultivars
Authors: Trappe Jon M. , Karcher Douglas E. , Richardson Michael D. , Patton Aaron J. 
Published: June 2011

ABSTRACTDivots created by a golf stroke are a natural occurrence on golf courses and the resistance of turf to divot injury is an important factor that should be considered when selecting a turfgrass. Therefore, the primary objective of this experiment was to quantify the divot resistance for various bermudagrass (Cynodon spp. Rich.) and zoysiagrass (Zoysia spp. Willd.) cultivars in a field experiment, with a secondary objective to compare evaluation methods for quantifying divot resistance. This study was conducted in Fayetteville, AR. Divot type, severity, and volume as well as a Turfgrass Shear Tester were used to determine divot resistance. ‘Riviera’ bermudagrass had the largest volume per divot (70 cm3), while the smallest divots (<28 cm3) were observed with ‘Cavalier’, ‘Diamond’, and ‘Zorro’ zoysiagrass. More force was required to displace divots from Diamond zoysiagrass than from Riviera, ‘Patriot’, or ‘Princess 77’ bermduagrass. Zoysia matrella (L.) Merr. consistently demonstrated greater divot resistance than Cynodon dactylon (L.) Pers. The four methods for evaluating divot resistance provided similar findings for divot resistance for the cultivars and species tested. These results provide researchers methods for evaluating divot resistance and will allow golf course superintendents to better select cultivars and species that will improve playing conditions and reduce divot injury.
A Novel Approach to Grass–Legume Management
Authors: Solomon Juan K. Q. , Macoon Bisoondat , Lang David J. , Parish Jane A. , Vann Rhonda C. 
Published: June 2011

ABSTRACTSpatially separated monoculture grasses and legumes within the same paddock (SS) may help alleviate constraints to the widespread adoption of legumes in pastures. A grazing study conducted during the winter–spring seasons of 2008 (steers, initial body weight [BW] = 236 ± 24 kg) and 2009 (heifers, initial BW = 245 ± 40 kg) at Raymond, MS, evaluated four forage systems (FS) at two stocking rates (SR; 3 or 6 animals ha−1). Using ‘Marshall’ annual ryegrass (Lolium multiflorum Lam.) and ‘Durana’ white clover (Trifolium repens L.), FS treatments were SS, monoculture grass (MG), monoculture legume (ML), and a binary mixture of grass and legume (MIX). Herbage mass was similar among FS at the high SR (1.9 Mg ha−1), but herbage mass at low SR was greater in MG, MIX, and the grass component of SS than ML and the legume component of SS (2.9 vs. 2.0 Mg ha−1). Among legume plots, SR did not affect herbage mass (1.9 Mg ha−1), but on grass plots, herbage mass was greater at low than high SR (2.9 vs. 2.0 Mg ha−1). Herbage accumulation was greater on grass than on legume plots (32 vs.13 kg ha−1 d−1), but there was no difference among FS within these two forage species. Low SR had greater herbage accumulation (27 kg ha−1 d−1) than high SR (21 kg ha−1 d−1). Average daily gain was greater on SS (1.12 kg) than on ML (0.97 kg), but neither was different from MG (1.08 kg) or MIX (1.00 kg), and greater on low SR than on high SR (1.09 vs. 0.99 kg). These results suggest that a SS system may be an option to enhance adoption of legumes in pastures.
Breeding Potential of Semidwarf Corn for Grain and Forage in the Northern U.S. Corn Belt
Authors: Schaefer Christopher M. , Sheaffer Craig C. , Bernardo Rex 
Published: June 2011

ABSTRACTConventional, nondwarf corn (Zea mays L.) hybrids grown in the northern U.S. Corn Belt are typically >2 m tall and have a 75‐ to 100‐d relative maturity (RM). Our objectives were to assess the potential of open‐pollinated COPOP1 semidwarf corn for grain and forage production, estimate genetic variances and heritability in COPOP1, and develop COPOP1 subpopulations that exhibit heterosis. In 2005 and 2006, we evaluated COPOP1 with four commercial, nondwarf hybrids at three plant population densities. Grain yield of open‐pollinated COPOP1 was about half of the mean yield of the conventional hybrids. However, COPOP1 had lower grain moisture (equivalent to 62 d RM) and better forage quality than the commercial hybrids. In 2007, COPOP1 was evaluated for performance when crossed to two divergent inbred testers, LH227 and LH295. Heritability was significant for grain moisture, plant height, and ear height in testcrosses to both testers but was significant for grain yield only in testcrosses to LH227. In 2009, bulk Cycle 0 (i.e., original COPOP1) and Cycle 1 testcrosses, nine semidwarf hybrids, COPOP1, and three commercial hybrids were evaluated at two plant population densities. Grain yield and most agronomic and forage traits did not improve between Cycle 0 and Cycle 1 in either testcross population. None of the semidwarf hybrids had higher grain yields than COPOP1. While semidwarf COPOP1 can serve as a source of useful variation for improving elite germplasm in the northern U.S. Corn Belt, further selection in COPOP1 must be done to develop improved semidwarf populations.
Fitness Evaluation of Rcg1, a Locus that Confers Resistance to Colletotrichum graminicola (Ces.) G.W. Wils. Using Near‐Isogenic Maize Hybrids
Authors: Frey T. J. , Weldekidan T. , Colbert T. , Wolters P.J.C.C. , Hawk J.A. 
Published: June 2011

ABSTRACTAnthracnose caused by Colletotrichum graminicola (Ces.) G.W. Wils. is an important stalk rot disease in maize (Zea mays L.). The impact of genetic resistance to plant pathogens is extremely important from both economic and environmental standpoints. The objectives of this study were to determine if any fitness costs were associated with the Rcg1 locus that confers resistance to C. graminicola in maize and to determine the effect of Rcg1 on grain yield in the presence of disease. Near‐isogenic hybrids (NIHs), created by crossing B73Ht and Mo17Ht with near‐isogenic lines (NILs) DE811 and DE811ASR(BC5), were evaluated under three treatment regimes: inoculation with C. graminicola, inoculation with water (wounding), and no inoculation. The experiment was conducted in a replicated split‐split‐plot design at six locations. Results indicate that the NIL DE811ASR(BC5) does not cause significant negative effects in hybrid combinations for most agronomic traits compared to hybrids made with the recurrent parent, DE811, and that there was no apparent fitness cost associated with Rcg1 in uninoculated or wounded treatments. The presence of Rcg1 reduced the overall yield impact incurred by infection in inoculated plots by almost three fold in comparison to the NIHs that lack the gene. These results, in addition to the asexual life cycle and limited variability of C. graminicola, imply that Rcg1 may be a durable resistance locus.
Molecular Characterization of the Mutant fap3(A22) Allele for Reduced Palmitate Concentration in Soybean
Authors: De Vries Brian D. , Fehr Walter R. , Welke Grace A. , Dewey Ralph E. 
Published: June 2011

ABSTRACTReduction of the palmitate concentration in soybean [Glycine max (L.) Merr.] oil is desirable for reducing the amount of saturated fat in the human diet. Chemical mutagenesis was used to develop the line A22 with the mutant allele designated fap3(A22) that reduces palmitate concentration in the seed oil. The objective of our study was to determine the molecular basis of the fap3(A22) mutation and develop a corresponding molecular marker to assist in future efforts for developing soybean cultivars with low saturated fat. DNA sequence analysis of the GmFATB1a gene of soybean revealed a single nucleotide polymorphism (SNP) resulting in a nonconservative amino acid substitution that was likely to be detrimental to the function of the 16:0–acyl carrier protein (ACP) thioesterase (TE) enzyme. An association analysis was conducted using F2–derived lines from a cross between the cultivar Archer (Fap3Fap3) and A22 (fap3fap3) that had been analyzed for their palmitate concentration by gas chromatography. Molecular genotyping of these lines established a perfect correlation between lines phenotypically classified as homozygous for the Fap3 allele or homozygous for the fap3(A22) allele based on their palmitate concentration. The polymorphism in the GmFATB1a gene was used to develop a functional, codominant marker that could be used to distinguish the Fap3 and fap3(A22) alleles in segregating populations. This marker will be useful for breeders who are developing low‐saturate cultivars with the fap3(A22) allele.
Genetic Diversity and Population Structure of Elite Foxtail Millet [Setaria italica (L.) P. Beauv.] Germplasm in China
Authors: Liu Zhengli , Bai Guihua , Zhang Dadong , Zhu Chengsong , Xia Xueyan , Cheng Ruhong , Shi Zhigang 
Published: June 2011

ABSTRACTChina is among the countries that have the most severe water deficiency. Due to its excellent drought tolerance, foxtail millet [Setaria italica (L.) P. Beauv.] has become one of the important cereal crops in China. Information on genetic diversity and population structure of foxtail millet may facilitate effective use of limited genetic resources in breeding programs. In this study, a selected panel of 128 accessions was screened with 79 simple sequence repeat (SSR) markers to investigate genetic diversity and population structure of foxtail millet. The panel was selected from 3356 germplasm collections from three major ecological areas of China: North, Northwest, and Northeast China. The mean genetic diversity was 0.75 and the mean polymorphism information content (PIC) was 0.72, indicating a high level of genetic diversity across the panel. Structure analysis identified six groups, which matches with their pedigree information, in general, but not with their geographic origins. Germplasm in Group 2 (G2) have unique geographic origins and pedigrees, which is different from other five groups; thus, crosses of accessions in this group to accessions from other groups are more likely to generate expected recombination for developing both conventional and hybrid cultivars.
A Developmental Genetic Basis for Defining Root Classes
Authors: Zobel Richard W. 
Published: June 2011

ABSTRACTRoot class nomenclature has not been standardized across species and groups (families). This has lead to a lack of transferability of conclusions from one species to another. The International Society for Root Research (ISRR) has approved a four class nomenclature for roots (Zobel and Waisel, 2010). A review of literature that has not been routinely cited by plant anatomists suggests that there are at least four classes and eight subclasses of root, based on developmental genetic characteristics across eudicots and monocots. The use of this classification scheme to develop research on specific classes of root may suggest a far more simple genetic basis than that suggested by current molecular and proteomic research.