bluuebunny/crossref_metadata_2025 huggingface dataset:
Irrigated Hybrid Maize Crop Yield Losses Due to Barley Yellow Dwarf Virus‐PAV Luteovirus
Authors: Beuve M. , Naïbo B. , Foulgocq L. , Lapierre H.
Published: July 2010

PAV, one of the luteoviruses inducing the barley yellow dwarf disease, greatly reduces yield of cereal crops and has been reported to cause reddening in several varieties of maize (Zea mays L.). However, there have been no reports that the virus causes significant reductions in size or yield of irrigated maize. Trials to assess the effect of PAV on maize yields were conducted for 3 yr with two hybrids (‘Déa’ and ‘Nobilis’) and two isolates of PAV (2t and L14). These two isolates differed in geographic origin and virulence on barley (Hordeum vulgare L.), but they multiplied similarly to wild isolates in leaves of maize hybrids. The virus was detected in maize leaves during the same period after inoculation in two out of three years. The reason for low levels of virus in leaves in the 1996 season may have been high temperatures (>30°C) following inoculation. Under these conditions, the virus was restricted to the roots for long periods. This blocking of virus migration and/or foliar multiplication was accompanied by less reddening, and there was almost no decrease in grain yield. High early leaf infection of the virus had little effect on the vegetative development of the hybrids (<10% reduction in plant height), but grain yield was between 15 and 20% lower for a production of 10 to 12 t ha−1 This drop in yield was due to fewer kernels of maize per ear, while the 1000 kernel mass was unaffected. The loss in yield was not affected by either the virus isolate or the maize hybrid, although the intensity of symptoms differed between hybrids. The data show that there are potential losses incurred by PAV on maize yield. Therefore, these findings justify the establishment of a breeding program.
Forage Yield and Quality for Monocrops and Mixtures of Small Grain Cereals
Authors: Juskiw P. E. , Helm J. H. , Salmon D. F.
Published: July 2010

Cereals are an important substrate for silage production in the short growing season of the northern Prairies. Our objectives were to determine the effects of seeding rate, species, and harvest date on the forage yield and quality of cereals. Three field studies were conducted to evaluate the productivity of barley (Hordeum vulgare L.), oat (Avena sativa L.), triticale (× Triticosecale rimpaui Wittm.), and rye (Secale cereale L.) grown as monocrops or in various mixtures. Seeding rates ranged from 250 to 750 seeds m−2 Harvest times were based on the maturity of the principal cereal in each mixture. Few effects of seeding rate on yield or quality were found, but when effects were found, higher seeding rates were associated with higher yields, lower moisture content, and higher fiber content. All treatments produced high quality forage as measured by neutral detergent fiber (NDF), from 515 g kg−1 for early‐harvested tests to 656 g kg−1 for late‐harvested tests, and acid detergent fiber (ADF) contents, from 310 g kg−1 for early‐harvested tests to 387 g kg−1 for late‐harvested tests. Protein was low, ranging from 61.5 to 101.0 g kg−1 Biomass yields ranged from 10.1 to 16.5 Mg ha−1 in the barley cultivar tests, 7.0 to 18.5 Mg ha−1 in the spring cereal tests, and 10.8 to 12.2 Mg ha−1 in the winter cereal tests. Although, some exceptions occurred, forage yield and quality of cereal mixtures were generally intermediate to monocrop production, especially for moisture and fiber content, suggesting that planting species mixtures could extend the harvest period and result in higher‐quality silage.
Quantitative Trait Loci for Antibiosis Resistance to Corn Earworm in Soybean
Authors: Rector B. G. , All J. N. , Parrott W. A. , Boerma H. R.
Published: July 2010

In more than 25 yr since the discovery of soybean [Glycine max (L.) Merr.] resistance to defoliating insects, attempts to introgress this trait into elite germplasm have been relatively unsuccessful. Resistance to defoliating insects in soybean is expressed as a combination of antibiosis (toxicity) and antixenosis (nonpreference). Both of these resistance modes are inherited quantitatively in soybean. The objectives of this study were (i) to use restriction fragment length polymorphism (RFLP) maps to identify quantitative trait loci (QTLs) in soybean for antibiosis against corn earworm (CEW) (Helicoverpa zea Boddie), (ii) to determine the relative magnitude, gene action, and genomic locations of these QTLs, and (iii) to compare them to previously detected soybean antixenosis QTLs. Restriction fragment length polymorphism maps were constructed in three soybean F2 populations segregating for antibiosis against CEW: ‘Cobb’ × PI171451, Cobb × PI227687, and Cobb × PI229358. Antibiosis was measured as larval weight gain in a detached leaf assay. The RFLP data were associated with insect bioassay data to detect QTLs for antibiosis in each cross. Variance component heritability estimates for antibiosis in the three crosses were 54, 42, and 62% in Cobb × PI171451, Cobb × PI227687, and Cobb × PI229358, respectively. An antibiosis QTL on Linkage Group (LG) M was detected in both Cobb × PI171451 and Cobb × PI229358 (R2 values of 28 and 22%, respectively). An antixenosis QTL was also significant at this location in the same two crosses. This was the only insect‐resistance QTL that was detected for both antibiosis and antixenosis. Antibiosis QTLs were also detected on LGs F and B2 in Cobb × PI227687 (R2 = 33 and 12%, respectively), and LGs G and J in Cobb × PI229358 (R2 = 19% for each). Antibiosis was conditioned by the PI (resistant parent) allele at the QTLs on LGs G, M, and B2, whereas the susceptible parent, Cobb, provided antibiosis alleles at the QTLs on LGs F and J.
Influence of Genotype and Environment on Isoflavone Contents of Soybean
Authors: Hoeck Joseph A. , Fehr Walter R. , Murphy Patricia A. , Welke Grace A.
Published: July 2010

Isoflavones in soybean [Glycine max (L.) Merr.] may have positive impacts on human health. The objective of this study was to determine the role of the genotype, environment, and genotype × environment interactions on isoflavone contents of soybean. Nine isoflavones were measured in six cultivars grown at eight locations during 2 yr. The mean contents of total isoflavones and six of nine individual isoflavones were significantly higher in 1996 than 1995. There were significant differences among locations in one or more years for total and individual isoflavone contents. The year × location interactions were significant due to changes in rank and magnitude among the locations during the 2 yr. The genotype, genotype × year, genotype × location, and genotype × year × location interactions were significant for total and individual isoflavone contents. Despite the significant genotype × environment interactions, the differences between the cultivars with the highest and lowest total and individual isoflavone contents were relatively consistent among the 16 environments. It should be possible to breed for isoflavone content as a quantitative trait in a cultivar development program.
Genetics of Four Male‐Sterile, Female‐Fertile Soybean Mutants
Authors: Palmer R. G.
Published: July 2010

Mutations affecting male cell and organ development may produce male‐sterile, female‐fertile plants that have application in plant breeding. In studies designed to test recombination frequencies and allelism, four such mutants were identified independently in soybean [Glycine max (L.) Merr.] populations that were characterized by chromosomal instability. The objectives of this study were to determine the inheritance of these four mutants and to test allelism with the seven known male‐sterile, female‐fertile soybean mutants. Allelism tests were done with male‐sterile, female‐fertile plants as female parents and known heterozygotes as male parents. All four mutants were inherited as single recessive nuclear genes. Male‐sterile mutants (MSM)‐1, MSM‐2, MSM‐3, and MSM‐4 were nonallelic to each other. Mutants MSM‐1, MSM‐2, and MSM‐3 were nonallelic to known mutants. They were assigned Genetic Type Collection numbers T357H, T358H, and T359H and the gene loci were assigned the symbols Ms7 ms7, Ms8 ms8, and Ms9 ms9, respectively. Mutant MSM‐4 was allelic to T259H (Ms2 ms2) and was designated T360H Ms2 ms2 (Ames). The T259H Ms2 ms2 mutant becomes T259H Ms2 ms2 (Eldorado). Dehisced anthers from MSM‐1 and MSM‐4 were similar in phenotype. Aborted pollen grains of MSM‐2 and MSM‐3 were different in phenotype from each other and from the seven known male‐sterile, female‐fertile soybean mutants. These four independently derived male‐sterile, female‐fertile mutants could be used in plant breeding to produce hybrid seed.
Enhancing Yield of Semidwarf Barley
Authors: Hellewell Kendell B. , Rasmusson Donald C. , Gallo‐Meagher Maria
Published: July 2010

Semidwarf barley (Hordeum vulgare L.) lines and cultivars with the sdw gene have not fulfilled early expectations of increased grain yield. Accordingly, both breeding and molecular mapping experiments were undertaken to enhance and evaluate performance of lines with sdw The objectives were to examine, in sdw semidwarf barley, the effect on grain yield of enhancing yield component traits—spike number, kernel number, and kernel weight—to confirm the reported allelic relationship between sdw and denso, to identify the chromosome location of sdw, and to determine the genetic relationship between sdw, height, and heading date. Eight tall barley lines having high yield‐component phenotypes or high grain yield were crossed to ‘Royal’, an sdw semidwarf, to obtain semidwarf populations for study. Grain yield of semidwarf lines was not significantly increased by enhancing yield‐component traits or by the use of high‐yield parents. Allelism tests and gene mapping procedures were used to determine the relationship between sdw and denso and to map the sdw allele location. The sdw gene was allelic to denso and mapped to barley chromosome 3H in the same region as denso The sdw allele reduced height by 10 to 20 cm and delayed maturity by ≈3 d. We hypothesize that the sdw allele itself, not linkage drag, is the basis for mediocre yield and late maturity of this short‐stature germplasm. The information obtained encourages use of alternative short‐stature sources.
Within‐ and Among‐Cultivar Genetic Variation in Alfalfa: Forage Quality, Morphology, and Yield
Authors: Julier Bernadette , Huyghe Christian , Ecalle Christian
Published: July 2010

Alfalfa (Medicago sativa L.) cultivars are synthetic populations formed from 8 to 200 parents and thus have a broad genetic base. Within‐cultivar variation was compared with among‐cultivar variation for energy value traits, morphological traits, and dry matter yield. Eleven cultivars, each represented by 15 clones of 7 to 20 genotypes, were evaluated in field plots simulating a dense canopy at INRA (National Institute of Agronomic Research), Lusignan in France. Six harvests spanning 3 yr were analyzed. Neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), enzymatic digestibility, leaf‐to‐stem ratio (LSR), number of stems, stem height, and dry matter yield were measured. Within‐cultivar variance accounted for 31 to 70% of the genetic variance for LSR and quality traits and 57 to 100% for morphological traits and dry matter yield. Large within‐cultivar variation for yield‐related traits could impart yield stability across environments, as a result of competition in alfalfa canopies. Phenotypic and genetic correlations were relatively low in each harvest for dry matter yield and NDF content, but high for NDF content and LSR. Within‐cultivar variation could be exploited as an additional source of genetic variation in breeding programs for quality traits to achieve a higher genetic gain per breeding cycle.
Growth and Yield Comparisons of Cotton Planted in Conventional and Ultra‐Narrow Row Spacings
Authors: Jost Philip H. , Cothren J. Tom
Published: July 2010

Cotton (Gossypium hirsutum L.) growers are faced with rising production costs and static or declining crop prices. One strategy with potential for reducing production costs entails growing cotton in ultra‐narrow rows with elevated plant populations. A 2‐yr field study was conducted in the Brazos Bottoms near College Station, TX to determine the differences in vegetative growth and yield parameters of cotton grown in ultra‐narrow and conventionally spaced rows. Four row spacings of 19, 38.1, 76.2, and 101.6 cm were planted with populations of 39.4 to 45.8, 18.2 to 20.7, 13.1 to 13.6, and 7.9 to 9.9 plants m−2, respectively. At crop maturity, plant height and node counts were reduced in the cotton grown in the 19‐cm row spacing. Canopy closure occurred more rapidly in the 19‐ and 38.1‐cm row spacings than in the wider row spacings. In 1997, a relatively wet growing season, yields were not affected by the row‐spacing treatments. In 1998, a dry growing season, yields in the 19‐ and 38.1‐cm row spacings were greater than those in the wider row spacings. The 19‐cm row spacing had 84.6% of the harvestable bolls at the first fruiting position and 76.1% of the bolls on Nodes 6 through 10, both percentages being significantly greater than those observed in the wider row spacings. Fiber length tended to be reduced in the 19‐cm row spacing relative to the other row spacings. Ultra‐narrow row cotton appears to be a viable option for producers to attempt to reduce costs while maintaining yields.
Management of a Mound‐Building Ant, Lasius neoniger Emery, on Golf Putting Greens and Tees Using Delayed‐Action Baits or Fipronil
Authors: López Rolando , Held David W. , Potter Daniel A.
Published: July 2010

The ant Lasius neoniger Emery can be a serious pest when its nesting and mound‐building activities occur on golf putting greens and tees. Controlling turf‐infesting ants is difficult because conventional insecticides usually fail to eliminate the subterranean queen. We compared the attractiveness of commercial and experimental ant baits to L. neoniger workers, and we evaluated baits containing novel, delayed‐action toxicants for selective control of L. neoniger on creeping bentgrass, Agrostis stolonifera L., golf tees. Efficacy of nonbait granular fipronil, a new phenyl pyrazole insecticide, also was evaluated. In choice tests, protein‐based baits were more readily taken than baits containing sugar‐ or oil‐based attractants. Abamectin‐, hydramethylnon‐, or spinosad‐based baits significantly reduced numbers of ant mounds and nests when applied either as spot or broadcast treatments. Two commercial baits, Advance Granular Carpenter Ant Bait, containing 0.011% abamectin B1, and Maxforce Ant Killer Granular Bait, containing 0.9% hydramethylnon, were especially effective. Spot‐treatment with either of these baits, using 1 g of bait per mound, eliminated 88 to 97% of the mounds within 3 d. Broadcast application of fipronil (0.028 kg a.i. ha−1) on heavily infested, sand‐based creeping bentgrass putting green turf in May provided ≈80% reduction of ant mounds at 7 d after treatment and 86% reduction at 60 d.
Development of PCR‐Based Markers for a High Grain Protein Content Gene from Triticum turgidum ssp. dicoccoides Transferred to Bread Wheat
Authors: Khan I. A. , Procunier J. D. , Humphreys D. G. , Tranquilli G. , Schlatter A. R. , Marcucci‐Poltri S. , Frohberg R. , Dubcovsky J.
Published: July 2010

Grain Protein Content (GPC) of wheat (Triticum aestivum L. and T. turgidum L.) is important for improved nutritional value and is also one of the major factors affecting breadmaking and pasta quality. A quantitative trait locus (QTL) for high GPC was detected a few years ago in the short arm of chromosome 6B from accession FA15‐3 of Triticum turgidum L. var. dicoccoides New molecular markers are presented here to facilitate the transfer of this high GPC gene into tetraploid and hexaploid wheat cultivars. Two sets of PCR (polymerase chain reaction) primers were designed to amplify regions of the non‐transcribed spacer of the XNor‐B2 locus. This locus was selected because it mapped on the peak of the QTL for GPC. The first pair of allele‐specific primers produced an amplification product only when the T. turgidum var. dicoccoides XNor‐B2 allele was present. The second pair of primers amplified fragment(s) of similar length in the different genotypes that after digestion with the restriction enzyme BamHI allowed differentiation of the T. turgidum var. dicoccoides allele. Four microsatellites markers were mapped on the short arm of chromosome 6B at both sides of the QTL peak and two on the long arm. Five additional amplified fragment length polymorphism (AFLP) markers were mapped into the QTL region on 6BS. These PCR markers together with 10 restriction fragment length polymorphism (RFLP) markers showed that the hexaploid cultivar Glupro, selected for high GPC, carries a distal segment of chromosome 6BL and a proximal segment of 6BS from dicoccoides accession FA15‐3 encompassing the segment with highest LOD score for the GPC QTL.
Seed Yield Variation in Blue Grama and Little Bluestem Plant Collections in Southern Manitoba, Canada
Authors: Phan Anh T. , Smith S. Ray
Published: July 2010

Inadequate seed supplies of adapted blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] and little bluestem [Schizachyrium scoparium (Michx.) Nash.] cultivars limits the use of these two species in the northern Great Plains of Western Canada. This study examined variation in seed yield traits of 11 blue grama and 14 little bluestem plant collections obtained from southern Manitoba, Canada to facilitate development of improved germplasm of these species. Measurements of seed yield traits including harvested air‐dried biomass, culm number, seedhead number, seed yield, caryopsis weight, and kernel index were taken from randomized complete block spaced‐plant nurseries. Tests were conducted for 2 yr at Winnipeg and 1 yr at Carman, MB, Canada. Collections within both species differed significantly for all traits. Significant collection × year (Winnipeg) and collection × location interactions were present for biomass and seed yield, and many of the seed yield‐component traits. While significant, the interactions resulted in few changes in rank among collections. Generally, the most northern collection in both species showed earlier anthesis, produced less biomass, and had lower seed yield than more southern collections. These findings indicate that indigenous plant collections of blue grama and little bluestem show high levels of genetic diversity for biomass, seed yield, and seed yield components, which provide opportunity for development of adapted cultivars with enhanced forage and seed production capability for the region.
Inorganic Soil Amendment Effects on Sand‐Based Sports Turf Media
Authors: Li Deying , Joo Young K. , Christians Nick E. , Minner David D.
Published: July 2010

Inorganic soil amendments have been suggested for use in turf to alleviate soil compaction, increase water retention and hydraulic conductivity, and improve many other soil physical properties. The objectives of this study were to determine the effects of ceramic, porous ceramic clay (PCC), calcined diatomaceous earth (CDE), and polymer coated clay (PC) on the physical characteristics of sand‐based media and to determine the effects of these amendments on bulk density following freeze–thaw treatments. Inorganic materials were added to a sand‐based golf green at 10% on a volumetric basis during construction in 1996. Data collected from the field included saturated hydraulic conductivity (Ksat), water retention, water release curves, bulk density and total porosity on compacted samples collected at construction, and undisturbed samples collected from the treated plots 1 and 2 yr after establishment. The PCC treatment had an 8 and 7% higher cation‐exchange capacity (CEC) than the control in 1997 and 1998, respectively. The PCC increased the Ksat by 26 and 20% in the compacted and undisturbed samples, respectively, in 1998. The CDE increased water retention by 13% in both compacted and undisturbed samples. Saturated hydraulic conductivity of the sand–inorganic mixtures decreased in the 2 yr, although some increases in Ksat were observed each spring. The Ksat of plots receiving all inorganic amendments was reduced by 75% in November of 1998. The Ksat values in the spring of 1999 increased from the low levels of 1998 by 19% (PC), 44% (control), 59% (ceramic), 72% (PCC), and 82% (CDE). The changes of Ksat over the winter may have been induced by freezing and thawing. These changes may not necessarily be caused by total porosity increases; instead they may be caused by increases in macropores. This hypothesis was further tested in the laboratory in a freeze–thaw study conducted in 1999. The PC, control, CDE, and PCC decreased bulk density by 10.7, 7.2, 2.5, and 2.2%, respectively, following a freeze–thaw cycle.
Inheritance of Multiple Transgenes in Wheat
Authors: Campbell B. T. , Baenziger P. S. , Mitra A. , Sato S. , Clemente T.
Published: July 2010

Understanding and predicting transgene linkage relationships is required to utilize efficiently transformation technologies in breeding programs. This study was conducted to determine the co‐transformation frequency of three gene sequences by means of a three‐plasmid co‐transformation system and to determine the mode of inheritance for two genes of interest. Twenty‐five independently transformed wheat (Triticum aestivum L.) plants were produced by microprojectile bombardment of 1080 immature embryos with a three‐plasmid system. Polymerase chain reaction (PCR) analyses of T1 progeny from each of the 25 T0 plants indicated co‐transformation of all three plasmids at a frequency of 36%. Two of nine transgenic families containing all three plasmids were characterized for the segregation of the two genes of interest in T1, T2, and T2 testcross generations by PCR. These data suggest that the two genes of interest are linked in both families studied. On the basis of the inheritance of the two genes of interest, one transgenic family would be desirable for use in a breeding program because it contained tightly linked genes, whereas the other family studied would not be desirable for use in a breeding program because the two genes segregated aberrantly.
Field Response to Selection in Alfalfa for Germination Rate and Seedling Vigor at Low Temperatures
Authors: Klos Kathy L. E. , Brummer E. Charles
Published: July 2010

Successful establishment of alfalfa (Medicago sativa L.) stands in early spring may require emergence and seedling growth at soil temperatures below 10°C. The objectives of this experiment were to evaluate changes in emergence and seedling height after laboratory selection in six cultivars at suboptimal temperature for (i) early germination (EG), (ii) high seedling vigor (HSV), (iii) EG + HSV, or (iv) late germination and low seedling vigor (LG + LSV). Cycles (C) 0 to 2 were evaluated for emergence 8 d after planting, seedling height (SH) 27 d after planting, forage dry matter yield, and other agronomic traits in field trials at Ames and Nashua, IA, in early spring 1998. Emergence was improved in all selected populations at Ames but not at Nashua; HSV and EG + HSV selection were most effective at improving emergence. After two cycles, seedling height was increased 21% by HSV selection and 9% by EG selection; however, the response among cultivars was highly variable. Combined EG + HSV selection was less effective than HSV alone at increasing height. Selection for LG + LSV did not reduce seedling height in the field even though large decreases were previously observed in the laboratory. Most gain from selection was realized with C1, possibly because the variable seed production environment in the greenhouse may have limited more consistent responses in C2. Seedling height selection at suboptimal temperatures in the laboratory successfully improved seedling height in the field in some alfalfa populations without changing other agronomic characteristics.
Inheritance of Resistance to Stem Rust in ‘Triumph 64’ Winter Wheat
Authors: Knott D. R.
Published: July 2010

The winter wheat (Triticum aestivum L.) cultivar Triumph 64 has resistance to a number of races of stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn) and has been used as a supplementary differential in identifying stem rust races. Triumph 64 was crossed and backcrossed to a susceptible wheat, LMPG, to study the inheritance of its resistance to races MCC and LCB. Four additional backcrosses to LMPG were made to produce near‐isogenic lines (NILs) carrying the Triumph 64 genes for resistance to races MCC and LCB. Twenty‐two NILs were tested with isolates of 10 stem rust races to determine the number of genes for resistance that were present. The genetic study indicated that Triumph 64 carries two genes conditioning resistance to both races MCC and LCB, and four genes conditioning resistance only to LCB. However, the NILs produced from Triumph 64 appeared to carry at least nine Sr genes, six giving resistance to both races MCC and LCB, and only one giving resistance just to LCB. Furthermore, some of the NILs were resistant to races TMH(15B‐1) and TMH(15B‐4) to which Triumph 64 is susceptible. One possible explanation for the results is that Triumph 64 carries one or more suppressors that were lost during the backcrossing, allowing the suppressed Sr genes to be expressed. Four of the NILs were resistant to all 10 races of stem rust and should be useful in wheat breeding.
Ascochyta Blight Resistance Inheritance in Three Chickpea Recombinant Inbred Line Populations
Authors: Tekeoglu Mucella , Santra Dipak K. , Kaiser Walter J. , Muehlbauer Fred J.
Published: July 2010

Ascochyta blight (caused by Ascochyta rabiei [Pass] Labr.) is a devastating and widespread disease of chickpea (Cicer arietinum L.). Studies of the genetics of resistance to blight have generated inconsistent reports due to year to year and between location variation in screening trial results. Most previous studies have relied on F2 or backcross populations for segregation analyses; however, inheritance patterns have been difficult to confirm because of the inability to repeat the evaluations in time and space. The objective of this study was to determine the inheritance of resistance to ascochyta blight in chickpea using recombinant inbred line (RIL) populations. The RILs were derived from two intraspecific crosses, PI 359075(1) × FLIP 84‐92C(2), ‘Blanco Lechoso’ × ‘Dwelley’, and one interspecific cross, FLIP 84‐92C(3) × C. reticulatum Lad. (PI 599072). The resistant parents, FLIP 84‐92C and Dwelley, had a common source of resistance derived from ILC‐72. Disease reactions of the parents and RILs were scored using a 1 to 9 scale and also by using the area under the disease progress curve (AUDPC). Segregation among RILs indicated that three recessive and complementary major genes with several modifiers conferred ascochyta blight resistance. Absence of one or two of the major genes confers susceptibility, whereas the presence of the modifiers determines the degree of resistance.
Physiological Performance of Synthetic Hexaploid Wheat‐Derived Populations
Authors: del Blanco I. A. , Rajaram S. , Kronstad W. E. , Reynolds M. P.
Published: July 2010

Wild ancestors of common wheat (Triticum aestivum L.) have been reported to have higher maximum photosynthetic rates than modern wheat cultivars. Synthetic hexaploids, obtained by crossing tetraploid wheat and Aegilops tauschii Coss., have proven useful as a source of resistance or tolerance to biotic and abiotic stresses. This study was conducted to determine whether synthetic hexaploids also could contribute genetic diversity to enhance leaf photosynthetic rate and other physiological traits. Three different populations of BC2F2:6 synthetic‐derived lines were evaluated at the Agricultural Research Center for the Northwest (INIFAP) Experimental Station, near Ciudad Obregon, Sonora, Mexico. Differences in maximum photosynthetic rate were detected among genotypes. Several synthetic‐derived lines showed higher photosynthetic rates than their recurrent parent. Staygreen, determined as days between senescence and physiological maturity, of most synthetic‐derived lines did not differ from the recurrent parents. Maximum photosynthetic rate was negatively associated with leaf area and positively associated with stomatal and mesophyll conductances, and leaf temperature depression. Mesophyll conductance accounted for 85% of the variation in maximum photosynthetic rate. These results suggest that synthetic‐derived wheat can be also a source of genetic diversity for important physiological traits such as enhanced photosynthetic rate.
Yield and Quality of Wheat, Triticale, and Elytricum Forage in the Southern Plains
Authors: Rao S. C. , Coleman S. W. , Volesky J. D.
Published: July 2010

Hard red winter wheat (Triticum aestivum L.) is a major cool‐season forage that couples with warm‐season perennials to provide livestock feed in the Southern Plains. Productivity and quality of wheat forage declines in April, creating a forage deficit period until warm‐season perennial grasses are available. Other cool‐season annual grasses with different growth patterns may provide growth during this period to fill this forage deficit. A field experiment was conducted on Brewer silty clay (fine, mixed, superactive, thermic Udertic Argiustoll) from 1994 to1997 to compare seasonal forage production patterns and yield and quality of winter wheat, triticale (× Triticosecale rimpaui Wittm.) and × Elytricum spp. (Triticum aestivum × Elytrigia spp. ‘OK‐906’). Aboveground whole‐plant biomass during late fall and early spring were greater for wheat than elytricum, but this trend was reversed in late spring and early summer. Average growing degree days to reach physiological maturity were 2500, 2670, and 3100 for wheat, triticale, and elytricum, respectively. Averaged across years, triticale and elytricum reached maturity 8.5 and 28 d after wheat, respectively. At physiological maturity, differences in biomass accumulation between wheat and triticale were minimal, but elytricum at physiological maturity produced 22% more total biomass, 3.5% less grain, and 28% greater straw yield as compared with wheat. Differences in straw in vitro dry matter disappearance (IVDMD) among species were minimal. Because of its prolonged vegetative‐growth phase compared with wheat or triticale, elytricum has the potential to fill the late spring forage deficit period and reduce supplemental feed cost for livestock.
Effect of Turfgrass on Soil Mobility and Dissipation of Cyproconazole
Authors: Gardner D. S. , Branham B. E. , Lickfeldt D. W.
Published: July 2010

Previous studies of pesticide fate in turfgrass have found less mobility and more rapid dissipation compared with studies using the same pesticide applied to bare soil. Few direct comparisons of pesticide mobility and dissipation in turfgrass vs. bare soil have been conducted. The mobility and persistence of cyproconazole [α‐(4‐chlorophenyl)‐α‐(1‐cyclopropylethyl)‐1H‐1,2,4‐triazole‐1‐ethanol] on bare soil (Flanagan silt loam; fine, smectitic, mesic Aquertic, Argiudoll) and turf containing varying levels of organic matter was examined under field conditions. Twenty‐centimeter‐diameter polyvinyl chloride (PVC) cylinders were installed in either creeping bentgrass turf (Agrostis palustris Huds.), or in turf in where either 33, 67, or 100% of the thatch and plant material had been removed. Cyproconazole was applied at 403 g a.i. ha−1 on 15 July 1996 and 8 July 1997. Replicate sampling cylinders were removed 2 h after treatment (HAT) and 4, 8, 16, 32, 64, and 128 d after treatment (DAT). Cylinder cores were sectioned into depths and assayed for cyproconazole by gas chromatography. On all sampling days, increasing the amount of surface organic matter decreased the amount of cyproconazole in the 0‐ to 1‐, 1‐ to 3‐, 3‐ to 5‐, and 5‐ to 15‐cm core sections. The amount of cyproconazole detected in the soil under a full stand of turf at 4 and 32 DAT was 1 and 11%, respectively, of that detected in bare soil. Cyproconazole residues never exceeded 20 μg kg−1 in the 15‐ to 30‐cm core section of any treatment. The half‐life of cyproconazole decreased from 129 d in bare soil to 12 d in a full bentgrass turf. Cyproconazole movement below 5 cm in the soil was reduced with increasing amounts of turfgrass thatch, and as little as one‐third of a full stand of turf greatly decreased the half‐life of cyproconazole. Application of cyproconazole to turfgrass results in less mobility and more rapid dissipation than is typically reported in other agronomic crops.
Effects of Differential Air and Soil Temperature on Carbohydrate Metabolism in Creeping Bentgrass
Authors: Xu Qingzhang , Huang Bingru
Published: July 2010

Bentgrass quality often declines under high temperature conditions. The physiological mechanisms of heat stress injury in creeping bentgrass are not well understood. The objective of this study was to determine the relative importance of air vs. soil temperature in the regulation of carbohydrate metabolism in two cultivars of creeping bentgrass (Agrostis palustris Huds.), ‘L‐93’ and ‘Penncross’. Shoots and roots of both cultivars were exposed to four differential air/soil temperatures: 20/20 (control), 20/35, 35/20, and 35/35°C in growth chambers and water baths. Under high soil (20/35) and high air/soil (35/35°C) temperature conditions, canopy net photosynthetic rate (Pn) of L‐93 and Penncross decreased dramatically; however, respiration rates of whole plants (Rplant) and roots (Rroot) increased to levels above those at 20/20 and 35/20°C within 8 d of treatment and then decreased to lower levels by 21 d after treatment. At 35/35°C, daily carbon consumption was 2 to 5 times carbon production for L‐93 and 3.5 to 12 times for Penncross. At 20/35°C, carbon consumption exceeded production within 10 d of treatment for both cultivars. Total nonstructural carbohydrate (TNC) contents in shoots and roots were reduced at 20/35, 35/20, and 35/35°C, compared to that at 20/20°C. Reducing soil temperature while exposing shoots to high temperature (35/20°C) increased Pn and carbohydrate content and reduced the carbon consumption to production ratio. The results suggested that roots play more important role than shoots in the mediation of carbohydrate responses to high air temperatures or high soil temperatures. High soil temperature alone or combined with high air temperature caused imbalance between photosynthesis and respiration and decreases in carbohydrate availability, which could contribute to the decline in shoot and root growth under high temperature conditions.
Storage Characteristics and Nutritive Value Changes in Bermudagrass Hay as Affected by Moisture Content and Density of Rectangular Bales
Authors: Coblentz W. K. , Turner J. E. , Scarbrough D. A. , Lesmeister K. E. , Johnson Z. B. , Kellogg D. W. , Coffey K. P. , McBeth L. J. , Weyers J. S.
Published: July 2010

Conserving hay at moisture concentrations >200 g kg−1 is known to cause spontaneous heating and negative effects on forage nutritive value. While these relationships have been evaluated extensively for alfalfa (Medicago sativa L.), less research has evaluated these factors in warm‐season grasses, specifically bermudagrass [Cynodon dactylon (L.) Pers.]. In this study, ‘Greenfield’ bermudagrass was grown on a Pickwick silt loam soil (fine‐silty, mixed, semiactive, thermic Typic Paleudult) and packaged in conventional rectangular bales at five concentrations of moisture (178, 208, 248, 287, and 325 g kg−1) and at high and medium bale densities (overall means = 208 and 186 kg m−3, respectively). Bale density had little effect on forage nutritive value after storage. Furthermore, bale density had no effect (P > 0.05) on indices of spontaneous heating (heating degree days >35°C, maximum temperature, and 30‐d average temperature), visual evaluation of mold, and dry matter (DM) recovery. Positive linear relationships occurred between concentrations of fibrous forage components and indices of spontaneous heating; coefficients of determination (r2) statistics were similar for each index of spontaneous heating that was used as the independent variable in these linear regressions. Concentrations of acid detergent insoluble N and neutral detergent insoluble N expressed on a DM basis were positively related to measures of spontaneous heating in close linear relationships (r2 ≥ 0.80). Regressions of other N fractions on measures of spontaneous heating exhibited lower coefficients of determination, but generally had significant slopes. Results of this study indicate that N in bermudagrass is very susceptible to reductions in bioavailability through heat damage during bale storage, and that this damage is increased with increases in initial bale moisture.
Isolation and Genetic Mapping of a Non‐Lethal Rice (Oryza sativa L.) low phytic acid 1 Mutation
Authors: Larson Steve R. , Rutger J. Neil , Young Kevin A. , Raboy Victor
Published: July 2010

Phytic acid (myo‐inositol 1,2,3,4,5,6 hexakisphosphate) is the most abundant form of phosphorus (P) in seeds and is virtually indigestible by humans or non‐ruminant livestock. It was hypothesized that one class of maize (Zea mays L.) and barley (Hordeum vulgare L.) low phytic acid mutations, designated lpa1, interrupt myo‐inositol supply during seed development and may be mutations of the myo‐inositol 1‐phosphate synthase (MIPS) gene. This study describes the isolation, inheritance, and genetic mapping of the first rice lpa1 mutation and reexamines the MIPS/lpa1 candidate gene hypothesis in rice. Grain from 3632 rice M2 lines, derived from gamma‐irradiated seed, was screened for the lpa phenotype. Two mutations, one lethal and one non‐lethal, were identified. The non‐lethal mutation is phenotypically similar to maize and barley lpa1 mutants and was designated rice lpa1‐1 Homozygosity for rice lpa1‐1 reduces the phytic acid portion of seed P from 71 to 39% and increases the inorganic portion of seed P from 5 to 32%, with little effect on total seed P. This rice lpa1 mutation was mapped to a 2.2‐cM interval on chromosome 2L. A single‐copy rice MIPS gene was mapped to a locus on rice chromosome 3 that is orthologous to MIPS loci on maize chromosome 1S (near maize lpa1) and barley chromosome 4H. Unlike maize lpa1, the rice and barley lpa1 mutations loci are clearly distinguishable from this canonical MIPS gene. No relationship can be inferred between the maize, barley, and rice lpa1 loci. Although this canonical MIPS gene may be an appropriate target for controlling seed phytic acid synthesis, modifications of other genes (e.g., maize lpa2, barley lpa1, barley lpa2, and rice lpa1) may also be useful in reducing grain phytic acid and improving the nutritional value of cereal grains and/or milling by‐products.
Endophyte Viability in Seedling Tall Fescue Treated with Fungicides
Authors: Hill N. S. , Brown E.
Published: July 2010

Commercial tall fescue (Festuca arundinacea Shreb.) cultivars containing non‐toxic endophytes (Neotyphodium coenophialum Glenn, Bacon, Hanlin) are available. Hence, seed testing objectives have changed to examining seed for viable endophyte. Seedling diseases occur during testing and this study compared effects of fungicides on endophyte infection of seedling plants. Endophyte‐infected ‘Jesup’ tall fescue seed were planted into cell packs and grown in the greenhouse. Chloroneb (1,4‐dichloro‐2,5‐dimethoxybenzene), terrazole (5‐ethoxy‐3‐(trichoromethyl)‐1,2,4‐thiadiazole), and propiconazole (1‐[[2‐(2,4‐dichlorophenyl)‐4‐propyl‐1,3‐dioxan‐2yl]methyl]‐1H‐1,2,4‐triazole) were applied weekly to plants beginning 7 d until 21 d post germination. In a second experiment, seedling plants received applications of Propiconazole at d 7, 14, 21 and all possible combinations. Seedling endophyte infection rates were higher when terrazole or chloroneb (83.1 and 78.1%, respectively) were applied compared with no fungicide (73.5%) or propiconazole (5.0%). Endophyte mortality was reduced but not eliminated when propiconazole application to seedling plants was delayed. Contact fungicides should be used to control seedling diseases when evaluating endophyte viability.
A fap7 Allele for Elevated Palmitate in Soybean
Authors: Stoltzfus David L. , Fehr Walter R. , Welke Grace A. , Hammond Earl G. , Cianzio Silvia R.
Published: July 2010

Soybean [Glycine max (L.) Merr.] oil with elevated palmitate content may be useful for food and industrial applications requiring oil with high oxidative stability. The mutant line A30 with ≈ 40 g kg−1 greater palmitate content than conventional soybean oil was developed by treating seeds of the line A89‐144026 with N‐nitroso‐N‐methyl urea. This study was conducted to determine the genetic control of elevated palmitate content in A30. Crosses were made between A30, its parent, and lines possessing the fap1, fap2‐b, fap3, fap4, fap5, or fap6 alleles for altered palmitate. The F1 seeds from reciprocal crosses between A30 and A89‐144026 did not exhibit maternal effects or dominance for palmitate content. The phenotypic and genotypic analyses of F2 seeds and F3 progeny indicated that A30 had an elevated palmitate allele, designated fap7, with additive gene action at a single locus. The fap7 locus was independent of fap1, fap2‐b, fap3, fap4, and fap5, but closely linked to the fap6 locus. The new allele can be used in combination with other alleles that control fatty ester composition to obtain unique oils for possible food and industrial applications.
Association of Total Sugar Content with Other Seed Traits of Diverse Soybean Cultivars
Authors: Geater Chandler W. , Fehr Walter R.
Published: July 2010

Total sugar content of soybean [Glycine max (L.) Merr.] seeds is considered to be important for the quality of some soyfoods. The objective of this study was to determine the association of total sugar with other seed traits of soybean to facilitate the development of cultivars with appropriate seed composition. Total sugar, protein, oil, fiber, and seed size of 23 conventional and food‐grade cultivars were evaluated in replicated tests at eight Iowa locations in 1998. Total sugar content was determined by acid hydrolysis, and protein, oil, and fiber were measured by near‐infrared reflectance (NIR). There were significant differences among the cultivars for all traits. Total sugar was most highly correlated (−0.81) with the sum of protein + oil (P + O). Seed size had a major influence on the association of total sugar with protein, oil, and fiber individually. Analysis of P + O by NIR was not influenced by seed size and should be a useful method of predicting differences among genotypes for total sugar content.
Root Development of Maize (Zea mays L.) as Observed with Minirhizotrons in Lysimeters
Authors: Liedgens Markus , Soldati Alberto , Stamp Peter , Richner Walter
Published: July 2010

Knowledge of root growth patterns is relevant for agronomic management practices. The growth of maize roots (Zea mays L.) was studied by means of minirhizotrons in lysimeters. Ten minirhizotrons (60‐mm outer diameter) were placed horizontally at soil depths between 5 and 100 cm, perpendicular to the maize row. The root density (roots cm−2) on images (2.43 cm2) was observed at weekly intervals. During the growing season, the root density increased to a maximum and then decreased, a pattern observed in 3 yr and at all depths and positions relative to the plant row. Growing degree days, compared with chronological time, did not improve the description of temporal root growth patterns. Maximum root density did not occur at the same time as pollen shed, in contrast to maximum leaf area. At shallow depths, the maximum root density was observed at the same time as pollen shed, while at a depth of 100 cm, the maximum root density occurred 2 wk after pollen shed. The maximum root density was observed about 10 d after pollen shed at most positions relative to the plant row. In conclusion, the maximum root density and hence resource uptake capacity of the root system was reached with some delay in relation to the vegetative development of the crop.
Cotton Fiber Length Is Affected by Far‐Red Light Impinging on Developing Bolls
Authors: Kasperbauer M. J.
Published: July 2010

Cotton (Gossypium hirsutum L.) fiber length is an important component of quality as defined by the textile industry. The fibers are single elongated cells that extend from the seed coat during development within bolls. It was hypothesized that elongating cotton fibers would be responsive to the far‐red (FR) to red light (R) photon ratio (FR/R) reflected to developing bolls. To test the hypothesis, plants were grown in trickle irrigated field plots over different colored soil covers that reflected high FR/R and low photosynthetic photon flux (PPF), or low FR/R and high PPF to developing bolls. Newly opened flowers were tagged over three replicate plots of each of four colors. After the flowers were fertilized, randomly selected young bolls were covered with aluminum foil to shield them from light during development. Others served as unshielded controls. The FR/R and PPF impinging on developing bolls affected biomass per area of carpel walls and the amount of FR transmitted into the bolls to the developing fibers. Fiber lengths were determined after the bolls matured. Fibers in unshielded bolls that developed over green and red (higher reflected FR/R) soil covers were significantly longer than those that developed over aluminum and white (higher reflected PPF). The difference in length of fiber developed in unshielded versus shielded bolls was greater over green and red than over aluminum and white indicating a greater response to increased FR/R than to increased PPF impinging on the developing bolls. These results suggest that reflected FR should be considered along with other environmental factors when developing innovative production systems that involve nontraditional row spacing, plant population densities, or soil surface conditions that can affect the photon ratios to which the developing plants are exposed.
Nitrogen/Potassium Fertilization Ratios for Bermudagrass Turf
Authors: Snyder George H. , Cisar John L.
Published: July 2010

Turfgrass fertilizers often contain approximately one‐half as much potassium (K) as nitrogen (N), on a weight basis. Since K fertilization has been shown to be very beneficial for turfgrass appearance and growth, higher rates of K fertilization, relative to N, have been suggested. The effect of K/N fertilization ratios on `Tifgreen' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] growth and quality was studied over a 3‐yr period in south Florida for three rates of N fertilization. Severe K deficiencies were observed in the absence of K fertilization. However, increasing K fertilization beyond a K/N fertilization ratio of 0.5 to 1 had virtually no effect on turfgrass appearance, growth, on resistance to bermudagrass decline, or on root weight. Increasing K fertilization relative to N fertilization did not provide commensurate increases in tissue K.