bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Analysis of a Null‐Allele for Lipoxygenase‐2 in Soybean1
Authors: Davies C. S. , Nielsen N. C.
Published: July 2010

Soybean [Glycine max (L.) Merr.] seeds contain at least three isomeric forms of lipoxygenase. We have identified a soybean line, PI 86.023, which is homozygous for a gene that confers the absence of the lipoxygenase‐2 isozyme. Analysis of electrophoretic banding patterns of seed extracts from the F2 and F3 progeny of crosses between PI 86.023 and breeding lines containing null‐alleles for lipoxygenase‐ 1 and ‐3 indicated that this gene was tightly linked to the Lx1 locus and independent of the Lx3 locus. We propose that the dominant allele for this gene be called Lx2 and the recessive null be designated lx2. Seeds were identified that lacked both lipoxygenase‐2 and ‐3, but none was found that lacked both lipoxygenase‐1 and ‐2. The lx‐2 null‐allele will be useful for investigating the effect of lipoxygenase‐2 on the production of off‐flavors during processing of soybean products.
Forage Yield and Yield Component Response to Divergent Selection for in Vitro Dry Matter Digestibility in Smooth Bromegrass1
Authors: Casler M. D. , Ehlke N. J.
Published: July 2010

Forage yield and quality tend to be negatively correlated with each other. Therefore, in selecting for improved forage quality, it is of interest to evaluate correlated selection responses for forage yield. The objective of this study was to evaluate forage yield, tiller density, and tiller dry weight of first generation smooth bromegrass (Bromus Inermis Leyss.) synthetics selected for high (B8HD) and low (B8LD) in vitro dry matter digestibility (IVDMD) and their parent population (B8). Each population was seeded in seven randomized complete blocks at Arlington, WI in 1981. Samples were taken at weekly intervals, 14 times throughout each of the 1982 and 1983 growing seasons for determination of forage yield, tiller density and tiller dry weight. Large‐plot yield trials were established in 1982 at Arlington, Marshfleld, and Spooner, and harvested in 1983 and 1984. Tiller dry weight increased during each growth period, while tiller density remained rather constant after June 1982. Forage yield of small‐plot samples was reduced 11.5% in B8HD and 5.5% in B8LD for a normal two‐cut management. These reductions were almost entirely due to reductions in tiller dry weight, suggesting possible inbreeding depression for tiller dry weight. Conversely, in large‐plot trials there was no evidence of selection response or inbreeding depression. The lack of agreement between large‐plot and small‐plot yield estimates could be due to population ✕ environment interactions and/or inherent differences in sampling techniques. It was concluded that forage yield was not significantly altered by selection for IVDMD. Future evaluation of forage yield should be based on the more accurate large plot determinations solely or as a supplement to smallplot yield component determinations.
Effect of Temperature and Photoperiod on Resistance to Purple Leaf Spot in Orchardgrass1
Authors: Berg C. C. , Zeiders K. E. , Sherwood R. T.
Published: July 2010

Experiments were conducted to determine whether resistance of orchardgrass (Dactylis glomerata L.) to purple leaf spot (caused by Stagonospora arenaria Sacc.) is environmentally stable. Regrowth leaves of 60 greenhouse‐grown genotypes were produced at four environmentally different dates (March, June, October, December) and were artificially inoculated. Spot size and spot frequency were scored on scales of 1 (no disease) to 8 (very severe disease). Plants scored <3.5 for either criterion were classified resistant. Only two of the 60 genotypes were resistant at all dates. Five genotypes were resistant at one or more dates, but moderately susceptible on at least one date. A significant genotype ✕ environment variance indicated resistance of these five genotypes was unstable. Three genotypes that were classified unstable and one genotype each that was classified resistant, intermediate, or susceptible, were then grown in combinations of temperature and photoperiods as follows: i) warm, short day; ii) warm, long day; iii) cool, short day; and iv) cool, long day. They were inoculated and incubated 48 h in the dark at 22°C and returned to their respective greenhouse or growth chamber environments in three trials. All genotypes formed moderately‐large to large spots in warm, short days, and all but the susceptible genotype formed small spots in cool, long days. The genotypes showed significant interactions with temperature or photoperiod for spot size and frequency. Repetitive artificial inoculations of genotypes during greenhouse screening programs may contribute to germplasm improvement by detecting and eliminating environmentally unstable genotypes.
Exotic Germplasm for Improving Grain Yield and Growth Rate in Pearl Millet1
Authors: Bramel‐Cox P. J. , Andrews D. J. , Frey K. J.
Published: July 2010

The potential of a germplasm source for improving certain productivity traits in a crop may be assessed by mating representative genotypes of the potential sources to the crop species or by measuring traits on the various genotypes per se. In this study, to evaluate the potential of three exotic strains of pearl millet [Pennisetum americanum (L.) Leekel to improve the grain yield and growth rate of cultivated pearl millet, a primitive landrace, a weedy relative, and a wild relative, were mated with two pearl millet inbred lines in a mating scheme designed to evaluate both the variability within the exotic strains and the progeny from their matings with the inbred lines. The experiment was evaluated in the rainy season of 1982 at Patancheru, India. The introgressed progeny were evaluated for grain yield and growth rate. The results of the study indicated that it was possible to select lines with transgressively increased grain yield and growth rate in all the matings. The exotic strain with the most potential to improve growth rate in pearl millet inbreds was the wild accession. The best exotic parents for improving grain yield (based upon a number of criteria) were the primitive landrace and the weedy relative.
Relationships between Rps2 and Other Genes Controlling Resistance to Phytophthora Rot in Soybean1
Authors: Kilen T. C.
Published: July 2010

The genes Rps4, Rps5, and Rps6 controlling resistance to phytophthora rot (caused by Phytophthora megasperma Drechs. f. sp. glycinea Kuan and Erwin) in soybean [Glycine mar (L.) Merr.] have recently been identified. Although tests for nonallelism with Rps1 and Rps3 were conducted, no investigation showing the relationship with Rps2 has been reported. The purpose of this study was to determine the relationship between Rps2 and Rps4, Rps5, and Rps6. The F3 lines from crosses between Rps2 and Rps4, Rps5, and Rps6 types were grown hydroponically and challenged with zoospores of race 1 of the pathogen. The 151 segregation ratios indicated that Rps4, Rps5, and Rps6 are nonallelic to Rps2. Because the genes studied are at different loci, Rps2 could be combined with any of them to develop soybean cultivars with resistance to several races of the pathogen causing phytophthora rot.
Inheritance and Expression of Three Genes Controlling Root Nodule Formation in Chickpea1
Authors: Davis Thomas M. , Foster K. W. , Phillips Donald A.
Published: July 2010

In continuing investigations of host genetic control of nodulation in the Rhizobium‐chickpea (Cicer arietinum L.) symbiosis, three γ‐irradiation‐induced mutants resistant to nodulation by Rhizobium strain CC1192 were characterized. When root temperature was controlled under greenhouse conditions, mutants PM665 and PM679 produced effective nodules at 24°C, but nodulation was strongly suppressed (PM665) or eliminated (PM679) at 29°C. Wild‐type parent P502 was effectively nodulated at both temperatures, but lacked nodules at 34°C. Mutant PM233 did not form nodules at any temperature tested. In trials with 16 other strains of Rhizobium that formed effective root nodules on P502, no nodules formed on PM233, and only a few nodule‐like protuberances formed on PM665 and PM679 when roots were maintained at 29°. In addition to the non‐nodulating (Nod−) phenotype, PM665 also produced ledlets with aberrant trichomes that were characterized by scanning electron microscopy. Genetic studies showed that recessive alleles at three different loci were responsible for the Nod− phenotypes in PM233, PM665, and PM679. Progeny from all crosses involving PM665 showed cosegregation of the Nod− phenotype and the aberrant trichome trait. On the basis of data presented, it is proposed that the symbols rn1, rn2, and rn3 be assigned to the loci producing the Nod− phenotype in mutants PM233, PM665, and PM679, respectively.
Effects of Boll Pilosity on Some Traints of ‘Pima’ Cotton1
Authors: Lee Joshua A.
Published: July 2010

A genetic stock, E‐2, of ‘Pima’ cotton (Gossypium barbadense L.), differs from commercial cultivars of Pima in that the leaves, stems, and fruit (boll) surfaces are densely pubescent, and the fiber is coarser. Because there is no evidence that dense pubescence on leaves and stems of Pima affects fiber traits other than grade, I questioned whether pubescent boll in Pima cotton is accompanied by coarse fiber, as with upland cotton (G. hirsutum L.). The first step in testing that hypothesis was to cross E‐2 with the very pubescent, although glabrous‐fruited, stock, ‘Pima S‐5‐H’, and examine an F2 population. All segregates displayed dense pubescence on leaves and stems but segregated for pubescence on bolls. Two contrasting phenotypes were selected for increase, F2 plants with pubescent (F2‐HB), and with glabrous bolls (F2‐GB). These were grown in replicated experiments with Pima S‐5‐H (P‐S‐5‐H), commercial Pima S‐5 (P‐S‐5), E‐2 with pubescent fruits (E‐2‐HB), and E‐2 with glabrous fruits and stems (E‐2‐SS). The P‐S‐5 entries graded lowest in leaf pubescence, 9.3 trichomes per 1 cm transect of abaxial surface of leaf, with the remaining entries distributed from 16.1 to 17.1. The entries were also significantly higher in lint percentage than the remainder, and had significantly larger bolls. Fiber length measures, 2.5 and 50% span, were about the same for all entries. There were some significant differences in length uniformity index, lint tenacity, and elongation, but these did not relate to differences in density of pubescence on various plant parts. The two entries with pubescent bolls, E‐2‐HB and F2‐HB, at 5.9 and 5.8, graded significantly higher in micronaire value (fiber perimeter) than the remaining entries at 5.0 to 5.3.
Plant Regeneration in Callus Cultures Derived from Young Inflorescences of Little Bluestem1
Authors: Songstad D. D. , Chen C. H. , Boe A. A.
Published: July 2010

Little Bluestem [Schizachyrium scoparium (Michx.) Nash], a warm‐season perennial grass, is valuable for range and conservation plantings in the Great Plains. The objectives of this study were to develop rapid vegetative propagation techniques to facilitate selection of superior genotypes and to elucidate differentiation patterns in tissue culture. Embryogenic call! were induced from 5‐ to 10‐mm segments of unemerged young inflorescences and maintained on Linsmaier and Skoog's RM medium supplemented with 5 mg 2,4‐Dichlorophenoxy acetic acid (2,4‐D)/L in the dark at 25°C. The explants were furnished from three genotypes selected from a breeding nursery. Plants regenerated through somatic embryogenesis from callus were grown on RM medium containing no hormones and with the same physical conditions as for callus initiation. Embryogenesis tended to be suppressed by 2,4‐D concentrations of 1 mg/L or higher, but was promoted by the addition of 1 to 5 mg kinetin/L. Regenerated plants grew to maturity in 24 weeks after being transplanted into pots in the greenhouse and were phenotypically similar to their source plants.
Selection for Improved Nutritional Quality of Alfalfa Forage1
Authors: Coors J. G. , Lowe C. C. , Murphy R. P.
Published: July 2010

Four diverse alfalfa (Medicago spp.) populations were screened in the field for nutritional quality. Acid detergent fiber of composite samples from first and second harvests was used to select for dry matter digestibility. First‐harvest percent transmittance, a Udy dyebinding procedure, was used to estimate crude protein concentration. Comparisons with standard cultivars showed that one cycle of selection was effective in reducing total cell wall, lignin, and amount of cell wall lignification and in increasing crude protein, hemicellulose (when expressed as a fraction of cell wall), in vitro dry matter digestibility, and in vitro cell wall digestibility in three of the four populations. Improved digestibility was associated with an increase in hemicellulose and a decrease in lignin fractions of the cell wall. Cellulose (when expressed as a fraction of the cell wall) did not change with selection. The mean crude protein concentration of the most improved population was 208 g kg−1, and total digestible dry matter was 775 g kg−1 as compared to 199 and 756 g kg−1, respectively, measured for the mean of standard cultivars. These differences correspond to an increased crude protein yield of approximately 200 kg ha−1 yr−1 and an increased digestible dry matter yield of approximately 525 kg ha−1 yr−1.
Effect of Genetically and Environmentally Induced Heading Date Differences on Yield and Adaptation of an Isogenenic Barley Pair1
Authors: Samail V. W. , Eslick R. F. , Hockett E. A.
Published: July 2010

Early maturity has long been recognized as crucial to crop adaptation in norther climates. This study was conducted to determine the specific effect of early maturity on yield and morphological character responses over a large number of environments. ‘Betzes’ spring barley (Hordeum vulgare L.) and its early heading backcross isotype ‘Erbet’ were grown in 214 environments. The effect of the mean 8‐ day reduction in heading dates on agronomic character responses in each environment was determined by using paired T‐tests, correlation analysis, and stability linear and curvilinear regression analysis. Betzes was 8 days later to head, 3 days later to mature (to 15% grain moisture), higher yielding (0.19 Mg/ha), had 75 g/kg more thin kernels, 125 g/kg fewer plump kernels, lower kernel weights (2.0 mg) 9 kg lower protein content, and taller plants (6.5 cm) than its early isotype Erbet when averaged over all environments. Correlation and linear stability regression analysis of the effect of early vs. normal heading date indicated that plant height and yield were primarily pleiotropically decreased by genetically reduced growth duration. Kernel weights, percent plump, and thin kernels, which all expressed a curvilinear response, were increased in the early line. In low yielding environments (increased stress), Erbet yielded as well as Betzes, and their yield patterns were correlated. Erbet yield patterns were not correlated to Betzes yield patterns in the higher (>4640 kg/ha) yielding environments.
Near‐Isogenic Barley Lines with Genes for Resistance to Powdery Mildew1
Authors: Kølster Per , Munk Lisa , Stølen Olav , Løhde Jørgen
Published: July 2010

Near‐isogenic lines differing in resistance genes were developed to study the effects of genes in barley (Hordeum vulgare L.) giving specific resistance to powdery mildew (Erysiphe graminis DC f.sp. hordei Em. Marchal). This paper describes breeding techniques, degree of similarity between isolines, and resistance genes present in the isolines. Twenty‐four donors of resistance genes were crossed and backcrossed five times to the spring barley cv. ‘Pallas’, and homozygous resistant BC5F2 plants were selected. Resistant lines were evaluated and selected for phenotypic similarity with the recurrent parent in the BC5F3, through BC5F7 generations. To select for genetic similarity in the region of the resistance locus Ml‐a, two linked hordein loci, Horl and Hor2, were studied in the BC5F4 generation. The resulting 24 near‐isogenic lines originated from single BC5Fs4 plants in each of 24 different progenies. With a few exceptions, the near‐isogenic lines were similar to the recurrent parent in morphological and physiological characteristics. Tests with the hordein genes indicated that double crossing‐over occurred very close to the resistance locus Ml‐a in five of the isogenic lines. With 22 powdery mildew isolates, 22 lines were similar to their donors in resistance reaction, while two lines gave reactions that indicated that they have lost a second resistance gene. The 24 near‐isogenic lines comprised 14 lines with one resistance gene each, and 10 lines with two or more resistance genes. All the isogenic lines differ in resistance. The degree of genetic similarity between the 24 isogenic lines and the recurrent parent Pallas is high according to the morphological and physiological observations and may be even higher than theoretically expected in lines with double recombination in the region of locus Ml‐a. These near‐isogenic barley lines are recommended for both practical and theoretical research work in the barley‐powdery mildew system.
Differentiation of Maize Genotypes for Aflatoxin Concentration in Developing Kernels1
Authors: Widstrom N. W. , Wilson D. M. , McMillian W. W.
Published: July 2010

Maize (Zea mays L.) hybrids have been shown to differ in the amount of aflatoxin found in kernels at harvest. The objective of this study was to determine the optimum time for measuring aflatoxin in samples of grain during ear maturation and thus evaluate the efficiency of measuring genotype differences in aflatoxin accumulation at grain maturity. Ten‐ear samples of two commercial hybrids were wound‐inoculated in the field with spores of Aspergillus flavus Link ex Fr. at 20 days after full silk and were collected at 30,40,50, and 60 days post‐silking from 10 replicates of each hybrid‐sampling date combination in 1982, 1983, and 1984. Data were recorded for aflatoxin concentration in the grain, percentage of ears with visible A. flavus, and insect damage. Significant differences occurred for aflatoxin concentration among years and also between hybrids and among sampling dates within years. Each hybrid had a unique linear rate of aflatoxin accumulation during maturation as determined by the regression of the logarithm of aflatoxin amount on sampling date. The accumulation rates of individual hybrids were not different from year to year. The magnitude of hybrid differences for aflatoxin accumulation was largest on the final sampling date as was the statistical difference between hybrids as determined by Fratios. Ratings of hybrids for insect damage and the percentage of ears with visible A.flavus tended to be smaller for ears harvested on the later sampling dates. The practice of evaluating hybrids based on differences in aflatoxin concentration in grain near physiological maturity (about 8 weeks post‐silking) seems justified, based on the results of this study.
Influence of Ethephon on Soybean Reproductive Development1
Authors: Urwiler Michael J. , Stutte Charles A.
Published: July 2010

Increased incidence of flower and young pod abscission occurs in soybean [Glycine mar (L.) Merr.] when subjected to environmental stresses, but the induction stimulus of the abscission process has not been investigated. The objective of this study was to investigate the role of ethylene on soybean reproductive development. Whole soybean plants were treated in a growth chamber with increasing rates of ethephon [(2‐chloroethyl) phosphonic acid] (an ethylene releasing chemical) at selected growth stages and ethylene release from treated tissue was monitored. The ethylene generated from ethephon was then investigated for effects on flower shedding and on pod and seed development. Also, selected plant tissue was monitored for ethylene release when subjected to stresses induced by excission. The results indicate that tissue ethylene level was elevated comparable to the amount of ethephon applied. Also, as the amount of ethephon was increased, the longer the tissue ethylene level remained elevated. Ethephon increased flower shedding when applied at rates of 100 mg L−1 or higher. However, only the 1000 mg L−1 rate had extreme detrimental effects on seed and pod development. Excised leaf and reproductive structures evolved ethylene in response to stresses induced by excision. The results demonstrate that ethylene can induce reproductive structure abscission, and stress can trigger ethylene biosynthesis in soybean.
Maize Pollen Viability and Ear Receptivity under Water and High Temperature Stress1
Authors: Schoper J. B. , Lambert R. J. , Vasilas B. L.
Published: July 2010

Pollen viability and ear receptivity may be important determinants of maize (Zea mays L.) seed set under drought and high temperature conditions. Little quantitative information is available concerning the influence of water and heat stress on pollen viability, as determined with seed‐set‐limiting pollen amounts, or ear receptivity. The purpose of this investigation was to determine the effect of a water deficit on ear receptivity, of heat and water stress on pollen viability using a seed‐set‐limiting amount of pollen in pollination, and the genotypic variability for these effects. During a 2‐y period, field‐grown potted maize plants, grown in a soil mix containing a Typic Argiudoll, were well‐watered or water‐stressed during flowering. Tassels included heat‐stressed, water‐stressed, and well‐watered. A second experiment, conducted on a Typic Haplaquoll, involved mixing heat‐stressed and nonstressed pollen with field‐produced R‐nj pollen and using kernel ratios to determine viability. The heat‐sensitive, commercial, and prolific hybrids decreased in kernel number by 31,15, and 9% respectively when the female plants were water stressed. Kernel number did not decrease when pollen from a water‐stressed plant was used. Heat stressing the tassel resulted in kernel number decreases of 87, 53, and 72% for the heat‐sensitive, commercial, and prolific hybrids, respectively. Pollen viability and amount shed limited seed set when the heat‐sensitive and prolific hybrids' tassels were heat stressed. Pollen viability limited seed set when the commercial hybrid's tassel was heat stressed. The pollen mixing experiment also indicated a large effect of heat stress on pollen viability. Thus, water and heat stress had large effects on ear receptivity and pollen viability, respectively, but pollen viability was unaffected by a water deficit.
Barley vs. Oat Companion Crops. I. Forage Yield and Quality Response during Alfalfa Establishment1
Authors: Brink G. E. , Marten G. C.
Published: July 2010

Oats (Avena sativa L.) is often chosen as a companion crop during the establishment of alfalfa (Medicago sativa L.). Recent research has shown barley (Hordeum vulgare L.) forage to have superior nutrient duality compared to that of oats. Our primary objective was to determine the forage quality and yield potential of representative barley and oat cultivars harvested at various maturity stages as companion crops during alfalfa establishment. Four cultivars each of barley and oats were established with alfalfa at each of two locations during each of 2 yr and harvested initially as forage at each of three small grain crop maturation stages. Alfalfa was also established alone (solo‐seeded) with and without herbicides, and was harvested at first flower. In vitro digestible dry matter (IVDDM) concentration of small grain‐alfalfa mixtures declined from 83 to 55 dag kg−1 (%) dry wt as companion crop maturation increased from five leaf to dough stage, whereas crude protein (CP) concentration declined from 29 to 9 dag kg−1 dry wt. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) concentrations increased with maturation until flag leaf stage, and then stabilized through dough stage. Average IVDDM concentration of mixtures of alfalfa and ‘Morex’ barley or ‘Lyon’ oats harvested initially at flag leaf stage was equivalent to or greater than that of solo‐seeded alfalfa established with or without herbicides. However, the average NDF and ADF concentrations of solo‐seeded alfalfa were lower than those of small grain‐alfalfa mixtures. Nutritive value and nutrient yield did not differ between soloseeded alfalfa established with and without herbicides. When barley and oat cultivars were used as companion crops for spring‐seeded alfalfa, barley mixtures harvested initially at the five leaf, flag leaf, or dough stage usually provided superior quality forage in the seeding year than did oat mixtures. However, annual IVDDM and CP yields were more influenced by location and year than by small grain species or cultivar.
Influence of the Rht1 Semidwarf Gene on Yield, Yield Components, and Grain Protein in Durum Wheat1
Authors: McClung Anna M. , Cantrell R. G. , Quick J. S. , Gregory R. S.
Published: July 2010

Many wheat breeding programs in the world utilize semidwarf germplasm to improve productivity and lodging resistance. Four sources of the reduced height gene Rhtl, were crossed with a conventional height cultivar to determine the influence of this gene on yield, yield components, test weight, and grain protein in durum wheat (Triticum turgidum L. var durum). Seedlings having the Rhtl/Rhtl (semidwarf) or rhtl/rhtl (tall) genotype were selected in the F2 generation of each cross based on their sensitivity to gibberellic acid. The F2‐derived F4 families were evaluated during the 1981 and 1982 field seasons. The semidwarf and tall height classes differed significantly for yield, test weight, kernel weight, tiller number, height, kernels per spike, spike length and grain protein. Semidwarfs produced significantly greater yield, number of tillers, and kernels per spike than the tall height class. The difference in tillering was found in only two of the four crosses and thus was not a general trend. Tall lines had consistently higher test weight, kernel weight, and grain protein than semidwarf lines. A positive correlation was observed between plant height and grain protein concentration (r=0.80, p<0.01). Factors in addition to the dilution of the protein in the kernel due to high yield are responsible for the low grain protein concentration associated with semidwarfs because low yielding semidwarf lines had significantly lower grain protein concentration than the high yielding tall lines. The use of the Rhtl gene in durum wheat breeding programs may contribute to higher grain yield in the absence of lodging but reduced grain protein levels may become a serious quality problem.
Selection for High and Low Harvest Index in Three Winter Wheat Populations1
Authors: Sharma R. C. , Smith E. L.
Published: July 2010

Low heritability of grain yield in wheat (Triticum aestivum L.) often results in a slow response to selection. Selection criteria other than grain yield per se are being sought by wheat breeders. Harvest index (HI), the ratio of grain yield to total biomass yield, may be a useful selection trait for yield improvement. A study was undertaken to estimate the heritability of HI and to determine the response to selection for high and low HI in three genetically diverse populations of winter wheat. Selections were made in the F3 generation and selected progenies were evaluated in replicated tests in the F4 generation. Realized heritability estimates for HI were intermediate in magnitude (0.44 to 0.60). Selection in F3 for high and low HI was effective in identifying F4 lines with high and low HI, respectively. Also, selection for high HI resulted in shorter plants with earlier heading dates and lower biomass yield. Genotypic correlations (rG) between HI and grain yield were low (rG = 0.04 to 0.23). Phenotypic correlations between HI and grain yield were relatively high in the F3 but much lower in the F4. Harvest index was negatively correlated with plant height and days to heading, while correlations between HI and biomass yield were mostly nonsignificant. Simple correlation coefficients between F3 and F4 means were higher for HI than for grain yield. Results indicated that HI in the F3 generation was a good predictor of HI in the F4, but a poor predictor of grain yield in the F4.
A Comparison of Apparent Photosynthesis in Sericea Lespedeza and Alfalfa1
Authors: Brown R. H. , Radcliffe D. E.
Published: July 2010

Sericea lespedeza [Lespedeza cuneata (Dumont G. Don.)] is well adapted to acid soils of the southern USA, but has a low yield potential. A greenhouse study was conducted to compare irradiance, temperature and water‐stress responses, and the photosynthetic potential of sericea and alfalfa (Medicago sativa L.). Shoot tips were enclosed in an acrylic chamber and responses of apparent photosynthesis (AP) to temperature across the range of 10 to 50°C and irradiance from 0 to 2 mmol quanta m−2, s−1 were determined on alfalfa and two cultivars of sericea. In a separate experiment, AP of the two species was compared across a range of tissue water potentials. In both experiments transpiration and dark respiration were also measured. Under all conditions tested, except very low irradiance and severe water stress, AP of sericea was one‐half or less than that of alfalfa. Maximum AP ranged from 22 to 30 μmol C02 m−2 s−1 for alfalfa, but only from 10 to 15 μmol CO2 m−2 s−1 for sericea. The two cultivars of sericea, ‘Serala’ and ‘AU‐Lotan’, did not differ in AP. Temperature response of AP was similar for the two species, with the optimum being about 25 to 30°C. Saturation of AP occurred at about one‐half of full sunlight in alfalfa and sericea at 30°C. Apparent photosynthesis decreased in both species with decreasing tissue water potential, and under severe water stress the rates tended to converge for sericea and alfalfa. Although responses to irradiance, temperature, and water‐stress were similar in sericea lespedeza and alfalfa, photosynthetic potential appeared to be much lower in sericea lespedeza.
Changes in Soybean Seed Quality from High Temperature during Seed Fill and Maturation1
Authors: Keigley P. J. , Mullen R. E.
Published: July 2010

Soybean [Glycine max (L.) Merr.] seed production is often located in areas where high temperatures prevail during part or all of the seed‐filling and maturation phases of seed growth, which may reduce the subsequent quality of harvested seed. Research was undertaken in 1981 and 1982 to study the effect of various lengths of high temperature during seed filling and maturation on soybean seed quality. Potted soybean (cv. Century) plants were transferred from the field to two growth chambers approximately 5 days before growth stage R5. Plants were exposed to a day/night temperature of 32/28°C (high) for 10, 20, 30, and 40 days after flowering and to a 27/22°C (low) temperature during the rest of the seed‐development and maturation period. The seeds were divided into two groups P1 (from main‐stem pods) and P2 (from branch and top main‐stem pods). Exposure to increasing periods of high temperature during seed fill resulted in a linear decline in seed germination, vigor, and physical quality. The average germination percentages were 84 and 50% when the low and high temperatures were extended to pod maturity, respectively. The percentages of small, etched, discolored, and wrinkled seed were 0.1, 3.6, 2.3, and 0.2%, respectively, under constant low temperature, but the percentages increased to 2.7, 20.1, 26.2, and 2.8% under constant high temperature. The high temperature directly influenced germination, vigor, and physical quality even when applied during the first 10 days of the seed‐filling period. Phomopsis sp. (pod and stem blight fungus) seed decay averaged less than 4% and did not account for the reductions observed in germination or vigor. Seedling axes dry weight and final average seed weight were the only measurements that showed any consistent difference between P1 and P2 seeds, with P1 seeds being more vigorous and having greater average seed weight than P2 seeds. The interaction of temperature treatments and seed position on the plant was not significant for any seed and seedling measurements. Factors that shorten the length of high‐temperature exposure during seed filling and maturation should reduce seed damage.
Digestion Kinetics of Sequentially Extracted Cell Wall Components of Forages1
Authors: Moore K. J. , Cherney J. H.
Published: July 2010

Rate and extent of cell wall digestion are important factors limiting utilization of forages in ruminant diets. The objectives of this experiment were to compare two methods of calculating these parameters and to compare the in vitro digestion kinetics of cell wall, cellulose and hemicellulose sequentially extracted from alfalfa (Medicago sativa L.), tall fescue (Festuca arundinacea Schreb.), sorghum ✕ sudangrass [Sorghum bicolor (L.) Moench], and wheat (Triticum aestivum L.) straw. Plant tissue was incubated in a rumen fluid‐buffer medium for 3,6, 9,12, 24, 36, 48, 72, or 96 h. Cell wall components were extracted sequentially using glass microfiber filters with sintered glass crucibles. The kinetic model used was: C = CDe −k(t‐L) + C1; where C = concentration remaining at time t, CD — digestible concentration, k = rate constant, L = discrete lag time, and C1 = indigestible concentration. Parameter estimates were obtained using a In‐linear least squares procedure and the multivariate secant nonlinear least squares procedure to determine if one method was more appropriate than the other. Both methods resulted in equations that described the data very well. Predicted and observed values were highly correlated (r > 0.99, P ≤ 0.01), and residual errors were similar for both procedures. There was, however, a bias associated with the nonlinear procedure, which tended to result in lower estimates of k and L when long lag times occurred. Within the grass species, there was no difference (P ≤ 0.05) among rate constants for digestion of cell wall components. Average rate constants for digestion of tall fescue, sorghum ✕ sudangrass, and wheat straw cell wall components were 0.046,0.059, and 0.045 h−1. Rate of digestion of alfalfa hemicellulose was 1.6 times faster than that of cellulose. Rate constants were 0.200 h−1 for alfalfa hemicellulose and 0.125 h−1 for cellulose. The results of this experiment indicate that use of the In‐linear calculation procedure is preferable when the digestion kinetics of species with a wide range of lag times are compared. Application of both calculation methods allowed for a comparison of cell wall digestion kinetics in vitro.
Inheritance of Red Endosperm in Alfalfa and Its Relationship to Color, Size, and Viability of Seed1
Authors: Sockness B. A. , Barnes D. K.
Published: July 2010

Most alfalfa (Medicago sativa L.) seed is some shade of yellow. In 1981, a plant (PE no. 7) with red seed was observed in a ‘Peruvian’ germplasm source. Our objectives were to: (i) determine the location of the color pigments in tissue layers and organs of alfalfa seeds; (ii) determine the relationship between red seed color, seed size, and seed abortion; and (iii) determine the inheritance of the red seed color trait. Seeds were dissected to determine which tissue layers and organs were contributing to seed color. Selfed seed (S1) was produced from 40 F1 plants (PE no. 7 ✕ ‘African’). Reciprocal backcrosses (BC1) were made between the Ft plants and the PE no. 7 parent. The BC1 seed was planted and the plants selfed (S1BC1). The BC1 plants also were cross‐pollinated with plants from four unrelated germplasm sources. Care was taken to recover all aborted (shriveled) seeds from all pollinations. Seed dissections indicated that the red pigments from PE no. 7 were associated with the endosperm. Red seed color was associated with decreased seed weight, and increased percentage aborted (shriveled) seeds. Genetic studies indicated that the red seed trait was controlled by one recessive gene with tetrasomic inheritance that controlled red color in the endosperm. A second gene produced an olive‐yellow seed coat color that could mask the expression of the gene that controlled red endosperm color. The endosperm controlled, red seed color trait appeared to be associated with lethal effects that caused seed abortion.
Canopy Temperature Based Irrigation Scheduling Indices for Kentucky Bluegrass Turf1
Authors: Throssell C. S. , Carrow R. N. , Milliken G. A.
Published: July 2010

Techniques currently used by turf managers to schedule irrigations promote overwatering, causing the inefficient use of water resources. The plant canopy temperature‐ambient air temperature differential is a good indicator of the water status of a plant. Field experiments were conducted to assess the potential of using plant canopy temperature, measured with an infrared thermometer, to schedule irrigations for Kentucky bluegrass (Poa pratensis L.) turf and to develop preliminary information to use stress degree day (SDD), crop water stress index (CWSI), and critical point model (CPM) indices to schedule irrigations. Data were collected in the summer and fall of 1983 from differentially irrigated plots. Treatments were: (i) well watered—irrigation at soil water potential of −0.04 MPa; (ii) slightly stressed—at soil water potential of −0.07 MPa; and (iii) moderately stressed—at soil water potential of −0.40 MPa. Variables were measured daily and included canopy temperature, ambient air temperature, solar radiation, vapor pressure deficit, open pan evaporation, wind speed, soil water potential, volumetric water content, number of days after irrigation, and the number of days after mowing. The data were used to develop the irrigation scheduling indices that were evaluated in 1984. Each of the indices was compared to tensiometer based irrigation scheduling at −0.07 MPa soil water potential. During a 25‐day period of hot, dry weather in 1984, water use and number of irrigation events (in parenthesis) were 98 (7), 112 (8), 140 (10), and 210 mm (15 times), respectively, for irrigation scheduling by tensiometer, SDDpos, CWSI, and CPM. Shoot density, verdure, and root weight were not significantly different for the treatments, but visual quality was higher for the CPM and CWSI treatments—reflecting the greater amount of water applied. Further refinement of these indices could allow them to be useful tools for irrigation scheduling.
Resistance to Leaf Rust in Hexaploid Wheat: Lr32 a Third Gene Derived from Triticum tauschii1
Authors: Kerber E. R.
Published: July 2010

The wild relatives of hexaploid wheat (Triticum aestivum L.) are important sources of new genes for the improvement and diversification of resistance to leaf rust (Puccinia recondita Rob. ex. Desm.) in common wheat breeding. Resistance to this pathogen was transferred to hexaploid wheat from accession RL5497‐1 of the diploid progenitor Triticum tauschii (Coss.) SchmaL Inheritance studies the diploid and hexaploid levels indicated that one gene conferred resistance to a wide spectrum of rust cultures. Resistance in the diploid was partially dominant while at the hexaploid level it appeared to be either partially dominant or recessive, depending on environmental conditions. The degree of seedling resistance, as indicated by infection type, was somewhat less in the hexaploid than in the diploid. This newly identified gene, designated Lr32, is located on chromosome 3D and, therefore, is different from the seedling resistance gene Lr21, previously transferred to common wheat from T. tauschii, and also different from Lr24, known to be on 3D but derived from Agropyron.
Effect of Chromosome 1B on Gluten Strength and Other Characteristics of Durum Wheat1
Authors: Josephides C. M. , Joppa L. R. , Youngs V. L.
Published: July 2010

Gluten strength is one of the most important quality characteristics of durum wheat (Triticum turgidum L. var. durum) and affects the cooking quality of spaghetti, reduces breakage loss of macaroni and other short goods during processing and transportation, and affects the organoleptic properties of pasta products. Chromosome 1B has been shown to be of special importance in determining gluten strength in durum wheat. Most of these studies have used polyacrylamide gel electrophoresis to separate the proteins of wheat and to show the relationship with measures of gluten strength such as sedimentation height, mixogram score, etc. In order to more directly assess the importance of chromosome 1B in comparison with other chromosomes, ‘Langdon’ durum nullisomic for chromosome 1B and disomic for chromosome 1D from ‘Chinese Spring’ was crossed with two strong gluten cultivars, ‘Edmore’ and ‘Kharkof‐5’. The 1B chromosomes from the two strong gluten cultivars were substituted for the 1B chromosome of Langdon by repeated backcrossing, and the resulting Langdon 1B substitution lines were compared with the recurrent parent Langdon and the donor parents in replicated field trials grown at three locations in North Dakota. In all cases, the 1B substitution lines had gluten strength like the donor parent rather than the Langdon parent. In other characteristics, the substitution lines resembled Langdon except that glume color of the substitution lines was like the donor parent. Consequently, it was concluded that chromosome 1B of durum wheat is far more important than any other chromosome in determining gluten strength.
Genetic Resistance to Boll Weevil Oviposition in Primitive Cotton1
Authors: McCarty J. C. , Jenkins J. N. , Parrott W. L.
Published: July 2010

Boll weevil (Anthonomus grandis Boheman) resistance was identified in several photoperiodic primitive accessions of cotton (Gossypium hirsutum L.) in the early 1970s. Two of these primitive accessions, T‐326 and T‐1180, were each crossed to ‘Deltapine 16’ and progeny with day‐neutral (DN) flowering habit were selected. These progeny were then backcrossed twice to their respective primitive parent and selected for day neutrality after each backcross. The resulting progenies were evaluated for boll weevil oviposition using a new laboratory technique. Significantly less oviposition was found on BC2F4 progeny of T‐326(DN) and T‐1180(DN) than on the control, ‘Stoneville 213’. These progeny expressed resistance as 57 and 54% as much oviposition, respectively, as on Stoneville 213 in the laboratory test; resistance also was noted by others in field tests. The level of boll weevil resistance found in the progenies of T‐326(DN) and T‐1180(DN), when combined with acceptable agronomic performance, should be of value in pest management.
Effect of Physical Restraint on Seed Growth in Soybean1
Authors: Egli D. B. , Duncan W. G. , Crafts‐Brandner S. J.
Published: July 2010

The growth and development of an individual soybean [Glycine max (L.) Merr.l seed is an important part of the yield production process; however, the effect of fruit size on the physiological processes controlling seed growth and final seed size are not completely understood. Thus, two experiments were conducted in a greenhouse to evaluate the effect of physical restriction of the fruit on seed growth. The plastic pod restriction device (PPRD) was constructed from a 6.35‐mm diam. plastic drinking straw cut into 4‐cm lengths. The PPRD's were placed over the fruit when the fruit fit tightly into the PPRD. All of the fruits on the treated plants (cv. McCall) were placed in the PPRD's and samples were taken at frequent intervals to determine seed fresh and dry mass. Application of the PPRD's had no effect on the number of fruits or seeds per plant at maturity in either experiment. Final size (mg seed−1) of seeds from the PPRD's was decreased relative to control plants by 30 and 15% in Exp. 1 and 2, respectively. Mature seeds from the PPRD's were cylindrical in shape and had a higher N concentration. The initial seed growth rate (SGR) of seeds in the PPRD's was similar to the control seeds, however, when the seed mass reached 80 (Exp. 1) or 65 (Exp. 2) mg seed−1, the SGR was drastically decreased and there was no further increase in seed water content. However, seed maturation (seeds turning yellow and moisture level reaching 550 g kg−1) did not occur in the PPRD treatments until after the control seeds matured. The PPRD's provide a useful technique to study the effects of physical restraint on seed growth. The data demonstrate that physical restraint has a direct effect on the ability of the seed to accumulate dry matter.
Induction of Adventitious Shoots in Cotton1
Authors: Lee Joshua A.
Published: July 2010

Plants of the tetraploid cotton species Gossypium hirsutum L. ordinarily produce secondary shoots only from axillary buds. Destruction of the primary shoot by excision below the cotyledonary axils occasionally leads to the production of adventitious shoots. Two plants of the cultivar Coker 201 produced adventitious shoots from what appeared to be callus tissue growing outward from stem cambium after 12 plants had been severed at the ground line. A plant of the “honseyard” stock Orinoco produced several shoots from globular masses of tissue that grew from the roots after the shoot was removed. Another plant of Orinoco, grown from seed produced on the first, produced shoots at two sites near the ground line of a stump from which the trunk had been removed. After removal of the shoots, the plant grew three additional groups of shoots, including one group from a root about 2 cm from the stump.
Line Source Irrigation to Assess Maize Inbred Line Stability1
Authors: Wicks Z. W. , Carson M. L.
Published: July 2010

Stability of inbred lines over a range of environments is variable. The objective of this research was to evaluate field response of inbred lines grown under line source irrigation as a predictor of yield stability of inbred lines over environments. Stability regression analyses were computed on yield data of five widely used inbred lines from a single line source experiment and from an interregional study grown at seven locations. Stability response slopes of inbred line performance under a line source irrigation system and in interregional testing were in perfect agreement when compared by rank order correlation. Line source irrigation experiments could serve as a time and moneysaving alternative to testing at numerous locations in a program of selecting for inbred line performance stability.
Primary Trisomics in Sugarbeet. II. Cytological Identification1
Authors: Romagosa I. , Cistue L. , Tsuchiya T. , Lasa J. M. , Hecker R. J.
Published: July 2010

Cytological identification of primary trisomics is an important part in the cytogenetic study of a species. The objective of this study was the Cytological identification of nine primary trisomic types in sugarbeet (Beta vulgaris L.). Karyotype analyses were conducted in somatic metaphase and late‐prophase cells. All nine types of primary trisomics in sugarbeet were cytologically identified by means of somatic karyotype analysis. Not all extra chromosomes could be identified with certainty at metaphase because of their similarity in size and arm ratio. Somatic prophase analysis was found to be useful in confirming the results of metaphase analysis of the extra chromosome present in some trisomic types.