bluuebunny/crossref_metadata_2025 huggingface dataset:
Barley Cultivar Identification by Polycrylamide Gel Electrophoresis of Hordein Proteins: Catalog of Cultivars1
Authors: Gebre H. , Khan K. , Foster A. E.
Published: July 2010

Polyacrylamide gel electrophoresis (PAGE) of hordein polypeptides was used to identify and catalog barley (Hordeum vulgare L.) cultivars. An electrophoregram formula was prepared for each cultivar using relative band mobility (based on the ‘Betzes’ reference band 0.50). Forty cultivars were separated into 17 groups. Group was largest with 12 cultivars, six other groups contained more than one cuitivar, and only 10 cultivars showed unique hordein band patterns. Some differences, mainly due to presence or absence of faint bands, were observed among cultivars within groups. It was possible to differentiate cultivars currently grown in North Dakota into five groups which included: 1) ‘Glenn’, ‘Morex’, ‘Robust’, ‘Hazen’, and ‘Bumper’; 2) ‘Azure’; 3) ‘Larker’; 4) ‘Bedford’; and 5) ‘Hector’. Banding patterns of Glenn, Morex, Robust, Hazen, and Bumper were identical. The malting cultivars Robust and Morex and the feed types Bedford and ‘Klondike’ have similar kernel characteristics. Using PAGE, it was possible to differentiate the two malting types from the two feed types and also differentiate between Bedford and Klondike. Also, hordein band patterns of six single kernels from each of 38 cultivars were compared with a meal sample from each cultivar with Betzes as a reference. In general, single kernels gave hordein band patterns identical to those of meal samples, but intensity of bands usually was fainter. Single kernels gave better resolution than meal samples. Of the cultivars analyzed, 25 showed identical hordein band patterns in single kernels and their corresponding meal samples, while 13 showed differences between their meal and/or among single kernel bands.
A Comparison of Sexual and Asexual Populations of Puccinia coronata for Traits of Aggressiveness in the Field1
Authors: Oard J. H. , Simons M. D.
Published: July 2010

We tested the hypothesis that sexual reproduction produces greater genetic variation than asexual reproduction and enhances the potential for selection of isolates with higher levels of aggressiveness. Certain traits of aggressiveness were compared in two field seasons between sexually and asexually derived uredial isolates of Puccinia coronata Cda. from Minnesota and Texas, respectively. Greater variation among isolates was found in the sexual than in the asexual population for traits that measured yield loss on the cultivars, ‘Clintford’, ‘Noble’, and ‘Otee’, but not on ‘Lang’ or ‘Richland’. The lack of differences between populations for variation of the measured visual traits was due to a relatively large genotype ✕ environment interaction. Low heritability values of resistance, as estimated by yield and seed weight indexes, in the asexual population were attributed to the strong genotype ✕ environment interaction, whereas corresponding values in the sexual population were affected less by the interaction. Data from the sexual Minnesota population may not accurately predict the range of variation for aggressiveness in the asexual Texas population due to different selection pressures operating within the two populations. Heritability estimates suggested that any advantage of sexual reproduction to increase variation in aggressiveness over that of asexual reproduction is trait, cultivar, and environment specific.
Selection for Seed‐Filling Period in Soybean1
Authors: Smith James R. , Nelson Randall L.
Published: July 2010

The duration of seed fill may be a physiological indicator of soybean [Glycine max (L.) Merr.) genotypes possessing high yield capabilities. In order for it to be of use in yield improvement programs, it must be highly heritable and be highly correlated with yield. The objective of this research was to determine if early‐generation classifications for seed‐filling period (SFP) can be maintained in later generations. Divergent selection for reproductive period was conducted on F2 single plants created by crossing ‘Williams’ ✕ ‘Kanrich’. Divergent selection for SFP was carried out in the F4 on single plants and in the F5 on unreplicated plant rows. Selected F4‐derived lines were grown at Urbana, IL in the F6 (1982) and F7 (1983) in replicated field plots to be evaluated for SFP classification. Soil classifications for the 1982 and 1983 experiments were a Drummer silty clay loam (Typic Haplaquall) and a Catlin silt loam (Typic Argiudoll), respectively. There was no relationship between reproductive period in the F2 generation and SFP in subsequent generations, but positive associations between SFP classifications in early generations (F4 and F5) and SFP classifications in later generations (F6 and F7) were found. This suggests the possible use of SFP in yield improvement programs for soybeans.
Resistance to Colonization by the Wheat Curl Mite in Aegilops squarrosa and its Inheritance after Transfer to Common Wheat1
Authors: Thomas Julian B. , Conner R. L.
Published: July 2010

Wheat streak mosaic is a destructive disease. The agents that cause it are vectored by the wheat curl mite (Eriophyes tulipae Keifer). While no resistance to colonization by this mite has been found in common wheat (Triticum aestivum L. em. Thell.), such resistance has been found in distant relatives of wheat from the genera Agropyron and Secale. This paper investigates Aegilops squarrosa L. (a close relative of common wheat) as a potential source of resistance to mite colonization. Two accessions of Ae. squarrosa were tested in a growth cabinet for resistance to mite colonization. One accession was found to be resistant while the other was susceptible. Following transfer of this resistance to common wheat, crosses were made between resistant (AC PGR 16635) and susceptible inbred parents and their progeny. Genetic segregation in three filial generations (F1, F2, and F3) and two backcross generations (B1 F1 [F1 by susceptibles] and B2 F1 [resistant B1 F1 by susceptibles]) indicated that resistance was conditioned by a single dominant gene with normal Mendelian behavior. It is suggested that this trait be referred to as resistance to curl mite colonization, that its abbreviation be Cmc, and that this particular gene be designated Cmcl. Since the chromosomes of Ae. squarrosa are also present in common wheat, Cmcl should recombine normally without the complication of a large, attendant linkage block that exists with translocated Cmc genes derived from Secale or Agropyron.
Gene Locations for Heading Date Using Reciprocal Chromosome Substitutions in Winter Wheat1
Authors: Zemetra R. S. , Morris R. , Schmidt J. W.
Published: July 2010

Heading date, which is one of the developmental stages of wheat (Tritlcum aestivum L.) that contribute to maturity, is therefore significant trait from an economic standpoint. Reciprocal sets of chromosome substitution lines in duplicate between two hard red winter wheat cultivars, Cheyenne and Wichita, were used to identify chromosomes that carried genes for heading date. The materials were planted in the field at Lincoln, NE using a randomized complete block design with three replications. Heading dates were recorded when 50% of the plants in the two center rows of each four‐row plot had the basal spikelets emerged from the boots. Heading dates were converted to number of days to heading from 1 May for statistical analyses. Wichita appeared to carry major genes controlling heading date on chromosomes 3A and 3D, while Cheyenne carried major genes on 3A, 3D, and 6A. The genes from Wichita accelerated heading of Cheyenne and those from Cheyenne delayed heading of Wichita. Three types of responses were obtained with respect to the duplicates of each substitution line. In the first type, one duplicate differed significantly from its recipient parent but the duplicates did not differ significantly. This behavior could indicate a genetic control of heading date, with Cheyenne chromosomes 1D, 2D, 4D, and 5A having minor effects in Wichita background. In the second type, two lines had significant differences between duplicates and also between one duplicate and its recipient parent. This type of response suggested that there were differences in the genetic backgrounds of the duplicates and that additional backcrosses were needed. In the third type, two lines had significant differences between duplicates but none between either duplicate and its recipient parent, indicating a possible environmental effect.
Recurrent Phenotypic Selection for Resistance to Brown Leaf Spot in Smooth Bromegrass1
Authors: Berg Clyde C. , Sherwood Robert T. , Zeiders Kenneth E.
Published: July 2010

Smooth bromegrass (Bromus inermis Leyss.) cultivars are susceptible to brown leaf spot [caused by Pyrenophora bromi (Died.) Drechs.]; however, there is variation among plants within cultivars for lesion size. The objective of this research was to determine the effectiveness of recurrent phenotj pic selection as a method of breeding for resistance to brown leaf spot. The source population (Cycle 0) was 93 plant introduction lines and five cultivars. Four cycles of selection for reduced lesion size were conducted using artificial inoculation in the greenhouse. A test comparing the four cycles and the check cultivars Saratoga and Baylor was conducted in the greenhouse. Mean lesion size, lesion frequency, and overall disease severity were significantly lower for Cycle 4 than for previous cycles. The percentage of plants in each severity class shifted to higher percentages in lower rating classes in Cycle 4 compared to previous cycles and check cultivars. However, even in Cycle 4 some plants were rated as moderately susceptible. The correlations between lesion size and lesion frequency, lesion size and overall severity, and lesion frequency and overall severity (476 df) were 0.64, 0.90, and 0.83, respectively (P<0.01). Methods of inoculation and incubation have been developed that were effective and reliable in screening for resistance to brown leaf spot. Four cycles of selection resulted in a significant increase in the level of resistance to brown leaf spot in smooth bromegrass.
Susceptibility to Root‐Knot Nematodes in Cotton Lines Resistant to the Fusarium Wilt/Root‐Knot Complex1
Authors: Starr J. L. , Veech J. A.
Published: July 2010

The cotton (Gossypium hirsutum L.) breeding lines CABCS'‐1‐81, CAHUS‐2‐81, and LEBOCAS'‐3‐81, developed by the multiple adversity resistance (MAR) technique, have been reported to be resistant to the fusarium wilt [Fusarium oxysporum Schlecht f. sp. vasinfectum (Atk.) Synd. and Hans.]/root‐knot nematode [Meloidogyne incognita (Kofoid and White) Chit.] complex. Host wilting was the sole criterion upon which resistance to the complex was based. Resistance to the nematode, usually predicted upon the inability of the nematode to reproduce on the host, was never directly measured. Our objective, therefore, was to measure the resistance of these breeding lines to the nematode alone. When nematode inoculated plants were grown in 15 cm pots in replicated greenhouse tests, the cotton breeding lines supported levels of M. incognita egg production that did not differ from that produced on the nematode susceptible ‘TAMCOT SP37’. All lines supported greater (P = 0.01) egg production than did the root‐knot nematode resistant ‘Auburn 634’. In replicated microplot tests, seed cotton yields of the breeding lines were not different from that of the susceptible TAMCOT SP37 at several nematode inoculum levels. Similarly, reproduction of M. incognita on susceptible and putatively nematode‐resistant cotton lines did not differ in microplot tests. Thus, while the cotton lines CABCS'‐1‐81, CAHUS‐2‐81, and LEBOCAS‐3‐81 may be more resistant under field conditions to fusarium wilt than is TAMCOT SP37, our study indicates they are not more resistant to M. incognita. Therefore, the indirect selection for resistance to root‐knot neniatodes based on host wilting, even in the presence of both pathogens, was found to be an inadequate test of resistance to M. incognita.
Planting Patterns and Soybean Yields1
Authors: Duncan W. G.
Published: July 2010

No satisfactory explanation for the effect of planting patterns on soybean [Glyclne max (L.) Merr.] seed yields under favorable growing conditions has been proposed. The purpose of this paper is to suggest two postulates that together explain soybean yield response to various planting patterns. They are: (1) seed yields continue increase with plant density to a limit that is well above that needed for almost complete light interception, and (2) yield is directly related to vegetative plant weight, all other conditions remaining the same. To illustrate the application of the first postulate, interplant competition is divided into three parts: Phase I in which there is no interplant competition for light among fully developed plants, Phase II in which canopy light interception is complete while seed yield increases with plant density, and Phase III in which yield per unit area is at a maximum for the planting patterns and is independent of plant density. The second postulate explains whyields per unit area differ with row width even when there is no difference in either plant density or canopy light interception. The validity of the postulates is tested using published data. No proof is offered for the postulates other than that they explain the data and seem physiologically possible.
Nitrogen Harvest Index in Oats: Its Repeatability and Association with Adaptation1
Authors: Rattunde H. F. , Frey K. J.
Published: July 2010

The proportion of total plant N that occurs in the grain of cereals is called the nitrogen harvest index (NHI). Twenty oat (Arena sativa L.) cultivars, 10 with high and 10 with low NHI, were used to study the repeatability of NHI measurements over environments and the association of NHI with certain grain and straw yield characteristics, i.e., mean yield, regression response to environments with differing levels of N availability, and stability of that yield response. The NHI values for the oat cultivars were determined at low N (0 kg ha−1) and high N (224 kg−1 in 1979 and 100 kg ha− in 1981). Adaptation to variable soil N was evaluated in 12 environments with varying N availability for 2 yrs. The NHI values were highly consistent across N levels (r=0.72**, significant at the 0.01 probability level) but less so across years (r=0.57**). The NHI values were less consistent across years at low soil N (r=0.18) than at high (r=0.75**). Selection for NHI in the high N environment gave realized heritabilities of 1.01 for high and 0.85 for low NHI lines. The NHI was positively associated with mean grain yield and response of grain yields to environmental productivity, but was inversely related to mean straw yield.
Chemical Thinning of Soybean with Bentazon1
Authors: Jeffers Daniel L.
Published: July 2010

Planting excessive amounts of seed to ensure adequate stands can sometimes result in dense stands that are susceptible to severe lodging. The objective of this research was to evaluate the feasibility of using chemical thinning of soybean [Glycine max (L.) Merr.] to adjust stands. Various seed mixtures of ‘Beeson 80’ (25 to 100%) and L75‐6631, a genotype sensitive to bentazon [3‐(l‐Methylethyl)‐lH‐2,l,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide], were planted in field plots of eight 38‐cm rows, resulting in a density of about 40 plants m−2. At various times throughout the season from stages V3 to R4.5, the L75‐6631 plants were removed by spraying the plots with bentazon. Yields were reduced if stands were thinned by more than 25% after first flowering. In a second experiment, seed mixtures of 70, 80,90, and 100% Beeson 80 (the remainder, L75‐6631) were planted in densities of 35, 50, and 70 seeds m−2. Sparse rainfall precluded significant lodging at any density. Chemical thinning occurred at V3, V5, V6 and R1.5. Yields were similar for all treatments. In all cases L75‐6631 plants were completely killed by treatment with 1.2 kg ha−1 bentazon applied during the vegetative stages. Later treatments (R3.5, R4.5) required a second spray using a one‐half rate of bentazon. For practical application, thinning should occur during vegetative stages to minimize yield effects and maximize control of sensitive weeds that may occur. Use of chemical thinning will require breeding of bentazon‐sensitive isolines of some common cultivars.
Pore Development and Seed Coat Permeability in Soybean1
Authors: Yaklich R. W. , Vigil E. L. , Wergin W. P.
Published: July 2010

The development of pores and permeability of the seed coat in soybean [Glycine max (L.) Merr.] was examined to determine the Name of their formation after desiccation in the pod and their functional relationship. Two replicates of four genotypes were grown in the field at Beltsville, MD. When plants reached growth stage R5 (seeds could be felt when the pods were squeezed), 50 pods were removed from Node 4 of different plants. Subsequently, a similar number was picked at 3 to 4 day intervals until harvest maturity. The pods were dried at room temperature and shelled. Pore formation in 50 seeds from each sampling interval was examined by observation with a dissecting microscope. Permeability of seed coats was determined by placing seeds in wet paper towels for 1 h. When seeds attained the mature shape, weekly samples of 15 seeds from each replicate were separated into seed coat and embryo, weighed, and the seed coat/embryo ratio determined. Seeds from the different harvest dates were also observed by scanning electron microscopy. After desiccation in the pod, soybean seed development progressed through three shapes; transversely narrowly elliptic, depressed ovate, and transversely broadly elliptic. Desiccation presumably caused pores and the impermeable seed coat to form during the depressed ovate stage. Prior to formation of pores and presumably the impermeable seed coat, the mature surface structure of the soybean seed coat developed. The seed coat surface elevated and the surface cells gathered closer together. Pores formed first around the hilum, encircled the seed parallel with the axis, and then formed on the abaxial surface (area covering the round face of the cotyledon). Surface deposits were observed on all seed coats. The amount of deposit, which varied on the surface of the seed coat, was derived from the endocarp of the pod wall. After attaining the mature shape, the seed coat/embryo ratio decreased as the seeds became larger. At maturity, genotypes with permeable seed coats had seed coat/embryo ratios <0.1. Seed coat/embryo ratios may be related to seed coat permeability.
Mass and Composition of Developing Soybean Seeds at Five Reproductive Growth Stages1
Authors: Dornbos D. L. , McDonald M. B.
Published: July 2010

Historically, days after flowering (DAF) has been the criterion for sampling developing soybean [Glycine max (L.) Merr.] seeds. Seed development rate, however, differs according to genotype and environmental conditions, leading to variable DAF values for the same seed development stage. Morphologically described growth stages (GS), in contrast, allow a rapid and convenient sampling method for seed development and composition studies. The purpose of this study was to categorize the changes in mass and composition of developing ‘Williams 79’ soybean seeds at five reproductive GS. Seed mass and composition studies demonstrated that R5 and R7 were accurate indicators of seedfill initiation and physiological maturity (PM), respectively. At R5, diy weight, protein, oil, and sugar quantity were low, while moisture content was high. Moisture content decreased slowly between R5 and R7, while seed dry weight, protein, oil, and sugar content increased. Between R5 and R7, 97% of the seed dry weight at maturity had accumulated. Monosaccharides represented 82% of the seed soluble carbohydrates at RS, but decreased to 8% by R6. Sucrose increased two‐fold between R5 and R6, then remained at a high level until R8. Raffinose and stachyose were undetectable until R7, when they represented 11 and 34% of the total soluble sugar, respectively. The largest increase in fatty acid quantity occurred between R5 and R6. Palmitic, stearic, and linolenic acid accounted for 68% of the total fatty acid at R4, but only 21% at R6. Oleic and linoleic acid accumulated most rapidly between R5 and R6, representing 79% of the fatty acid content at R6. Four acetate buffer soluble proteins were resolved by electrophoresis at R5 and eight at R6. Banding patterns remained constant between R6 and R8, while protein quantity of Bands 2 through 8 decreased. The quantity (mg seed−1) of each macro‐ and micro‐element increased at varying rates between R5 and R7. After R7, the seed moisture content decreased rapidly while the quantity and composition of stored components changed little. At harvest maturity (R8), seeds possessed 380 g protein, 230 g oil, and 160 g sugar kg−1 dry weight. These data serve as a useful characterization of changes in seed composition for future studies employing GS.
Relationship between Greenhouse and Field Ratings for Brown Stem Rot Reaction in Soybean1
Authors: Sebastian S. A. , Nickell C. D. , Gray L. E.
Published: July 2010

To justify greenhouse selection for disease resistance, greenhouse disease reactions should be indicative of disease reactions under field conditions. Field and greenhouse tests were conducted to determine the relationship between field and greenhouse reactions of soybean [Glycine max (L.) Merr.] lines to Phialophora gregata (Allington and Chamberlain) W. Gams, the muse of brown stem rot (BSR). Twenty‐five soybean lines of Maturity Group 111 and 20 soybean lines of Maturity Group IV were rated for BSR reaction in field and greenhouse tests. The BSR ratings included counts of nodes showing leaf and stem symptoms in both field plots and greenhouse pots. Visual estimates of leaf symptom incidence in field plots were also recorded. Greenhouse leaf symptoms were highly correlated with the reactions of soybean lines under field conditions where susceptible standards showed obvious leaf symptoms. Selection based on greenhouse leaf symptoms identified soybean lines with field resistance to BSR. Resistance was associated with a 12 to 16% yield advantage when disease developed to the point of causing leaf symptoms in susceptible soybean lines.
Stability Analysis: Where Do We Stand?1
Authors: Lin C. S. , Binns M. R. , Lefkovitch L. P.
Published: July 2010

To clarify the apparent confusion arising from the diversity of published stability statistics, and the relationship of these with the clustering of genotypes for similarity of response to environments, the interrelationship of nine stability statistics and nine similarity measures are investigated. The stability statistics fall into four groups depending on whether they are based on the deviations from the average genotype effect or on the genotype ✕ environment (GE) term, and whether or not they incorporate a regression model on an environmental index. These groups of stability statistics are shown to be related to three concepts: A genotype may be considered to be stable (i) if its among‐environment variance is small, (ii) if its response to environments is parallel to the mean response of all genotypes in the trial, or (iii) if the residual mean square from a regression model on the environmental index is small. Unfortunately, these three concepts represent different aspects of stability and do not always provide a complete picture of the response. In the alternative approach of cluster analysis, the similarity measures define complete similarity in three different ways: i) equality of genotype's response across locations, ii) equality of all within location differences, and iii) equality of all within location ratios. The advantage of the nonparametric approach is that a cultivar's response characteristics can be assessed qualitatively, without the need for a mathematical characterization.
Differential Responses of Soybean Genotypes Subjected to a Seasonal Soil Water Gradient1
Authors: Specht J. E. , Williams J. H. , Weidenbenner C. J.
Published: July 2010

The development of soybean [Glycine mar (L.) Merr.] cultivars specifically adapted to rainfed or irrigated production systems may require explicit selection for adaptation to drought‐prone environments or responsiveness to irrigation culture, respectively. To detect the existence of genotypic differences in soybean response to water, the agronomic performance of 16 cultivars was evaluated relative to six levels of a seasonal soil water gradient created by variable amounts of weekly irrigation. The fortuitous occurrence of minimal rainfall from early July to late August in 1983 and 1984 permitted a wide range in seed yield expression (ca. 1 to 4 Mg/ha) to be established across the gradient. As water application increased, maturity was delayed and seed quality (1983 only), plant height, lodging, seed per plant, 100‐seed weight (1983 only), seed yield, straw yield, and apparent harvest index (HI) were increased. When cultivar seed yields were regressed on June thru September water amounts, significant differences among genotypic regression coefficients were observed (range of 50 to 90 kg ha−1 cm−1 in 1983 and 27 to 82 kg ha−1 cm−1 in 1984). Consistently (across years) low coefficients for some cultivars (e.g. ‘Williams 82’, ‘Lawrence’, and ‘Amcor’), and high ones for others (e.g., ‘A3127’, ‘Century’, and ‘Fremont’), empirically characterized the former as being less sensitive to drought (and conversely, less responsive to irrigation) than the latter. Cultivar HI responses were quadratic, declining under severe water stress, but plateauing at an apparent asymptotic limit in well‐watered conditions. However, straw yield responses were relatively linear, suggesting that increases in vegetative dry matter may be the key to increasing total dry matter (and thus seed yields) in cultivars selected for use in irrigation culture.
Silk and Pollen Water Potentials in Maize1
Authors: Westgate Mark E. , Boyer John S.
Published: July 2010

Sexual reproduction depends on the transport of the male gamete to the egg along an aqueous path. In plants, this process causes reproduction to be particularly vulnerable to low water potentials (low ψW). Crops experience large yield losses when low ψW occur during reproduction, but the ψW are unknown for most floral parts in relation to the vegetative plant. Therefore, in maize (Zea mays L.) we measured the ψW of the pollen and stigmas (silks), two structures important to the fertilization process, and compared the ψW to those in the leaves. Plants were grown in the field and in a controlled environment in soil. When water was supplied, leaf ψW varied diurnally between −0.15 and −0.7 MPa. However, silk ψW showed little diurnal variation and ranged between −0.3 and −0.6 MPa. Freshly released pollen began the day at much lower ψW (−1.2 MPa) and decreased to very low ψW (−12.5 MPa) as the day progressed. Similar ψW were observed in the controlled environment and in the field. When water was withheld, leaf ψW decreased to about −1.7 MPa, silk ψW decreased to about −1.2 MPa, but pollen ψW was unaffected. Silk ψW followed changes in leaf ψW(r = 0.77) but pollen ψW did not (r = 0.28). These observations indicate that stigmatic tissues (silks) are in moderate hydraulic contact with the vegetative plant but the mature male gametophytes (pollen) are not. As a consequence, depletion of soil water affects the silks more than the pollen. This may explain earlier reports that low leaf ψW. had no effect on in vitro pollen germination. Also, the data show that pollen ψW is always substantially lower then silk ψW, assuring that water moves from the silks to the pollen. Because pollen having ψW as low as −12.5 MPa has been reported to be viable, pollen desiccation should not be a factor limiting grain production in maize in the field.
Influence of Harvest Date, Cultivar, and Sample Storage Method on Concentration of Isoflavones in Subterranean Clover1
Authors: Smith G. R. , Randel R. D. , Bradshaw C.
Published: July 2010

The isoflavones formononetin (7‐hydroxy‐4′‐methoxyisoflavone; FM), biochanin A (5,7dihydroxy‐4′‐methoxyisoflavone; BA), genistein (5,7,4′‐trihydroxyisoflavone; GE), and trace amounts of diadzein (7,4′‐dihydroxyisoflavone; DI) are present in subterranean clover (Trifolium subterraneum L.) in concentrations highly dependent on cultivar or germplasm source. The effects of harvest date and sample storage methods on isoflavone concentration of four subterranean clover cultivars were investigated using high performance liquid chromatography techniques. Leaves and petioles were harvested from cultivars ‘Tallarook’, ‘Nangeela’, and ‘Woogenellup’ and PI 209927 in March, April, and May, 1983 at Overton, TX. Samples were methanol extracted (7 days at 5°C) fresh, and after 24 weeks storage either frozen (−l2°C) or dried (48 h at 40°C). Free isoflavones were measured directly from the methanol extract while total (free + glycoside form) was measured in acid hydrolyzed (4 M HCI at 70°C, 2 h) extracts. Formononetin, BA, and GE were detected in all samples. Harvest date, sample storage, and clover cultivar had significant effects on the concentration of FM, BA, and GE. First and second order interactions were also significant for isoflavone concentrations. Isoflavone concentration decreased over harvest date for all cultivars except Woogenellup. Concentration of total FM in Woogenellup increased from 1.1 to 3.4 g kg−1 from March to May. Total isoflavone concentration was unaffected by frozen storage but was decreased by 30 to 50% in dried samples. We conclude that accurate classification of potential isoflavone concentration in subterranean clover should be derived from measurements at several harvest dates over the growing season. Total isoflavone concentrations in subterranean clover samples frozen for 24 weeks was closely related to concentrations in fresh samples.
Nitrogen Influences on Yield Determination in Maize1
Authors: Lemcoff J. H. , Loomis R. S.
Published: July 2010

The components of reproductive yield in maize (Zea mays L.) are influenced by the crop's status for C and N substrates at critical stages of development. The specific role of N was clarified by comparing plant performance under conditions that lead to differences in N and photosynthate supply per plant. This was achieved in a field experiment on a Mollic Haploxeralf with differences in initial N supply (0 and 167 kg N ha 1 added) and plant density (28 700 and 86 100 plants ha 1). Variations in grain yield came from changes in grain number per ear and grain weight. Number seemed to be controlled initially at pollination by emergence of apical silks. Weight variations arose mainly from variations in the duration of the effective grain‐filling period. The C/N uptake ratio to the ear during the initial phases of grain growth was nearly constant over treatments. Nitrogen supply seems to have affected initial spikelet weight through preanthesis events and that influenced the length of the exponential phase of grain growth. Carbon flow to the ear during the exponential phase, while highly correlated with leaf area per plant, seemed to depend more on the size of the grain sink.
Alfalfa Leaf Area as a Function of Dry Matter1
Authors: Sharratt B. S. , Baker D. G.
Published: July 2010

This study was undertaken to determine the relationship between leaf area and dry matter of alfalfa (Medicago sativa L.) to obtain leaf area estimates without having to make the time‐consuming area measurements directly. Alfalfa samples were taken from a wellwatered field crop during three growing seasons at the University of Minnesota‐St. Paul campus. Additional data were collected from the literature. A logarithmic transformation of the leaf area (LA), the leaf dry matter (LDM), and the total dry matter (TDM) data indicated that the relationships between LA‐LDM and LA‐TDM were not significantly different between data collected from our field study and those obtained from the literature. The relationships derived from both sources of data are: LA = 28.7 LDM0.993 and LA = 10.7 TDM0.992, where LA is in m2, and LDM and TDM are in kg. The standard error of estimate equalled 0.089 and 0.1 11 for the regression of LA on LDM and LA on TDM, respectively. The LA‐LDM and LATDM correlation coefficients (r) were greater than 0.99 and 0.99, respectively. These results indicate that leaf dry matter and, under some experimental situations, total dry matter determinations, can be used to estimate alfalfa LA in lieu of electronic meters or determining the leaf area‐dry weight ratio.
Selection Indices to Improve an Intermating Population of Spring Wheat1
Authors: Wells W. C. , Kofoid K. D.
Published: July 2010

The intermating population of spring wheat (Triticum aestivum L.) NDPl was created to be a source of both cultivars and parental lines for future breeding populations. The objective of this study was to predict the relative merits of four types of selection indices for improving NDPl, and to predict the gain in efficiency of selection from using information on secondary characters in the calculation of index weights. Smith‐Hazel, base, and desired gain indices were constructed to increase yield and percent protein and decrease plant height. Restricted selection indices were constructed to increase yield and eliminate undesirable correlated responses in percent protein and plant height. Comparisons were made based upon predicted responses from S1 family selection. Estimates of the population parameters were derived from 200 S1 families grown in two replications in the field in 1981 and 1982. Broad sense heritabilities for all measured characters were high. Genotypic and phenotypic covariances between yield and percent protein were negative, while covariances between these two characters and the characters plant height and kernel weight were positive. The Smith‐Hazel index maximized predicted gains in the aggregate genotype, with a predicted increase in yield of 9.6%, a decrease in plant height of 0.3%, and an increase in percent protein of 1.1%. Similar responses were predicted for the base and restricted selection indices. A 2.7% increase in yield and percent protein, and a 2.7% decrease in plant height were predicted for selection based upon a desired gain index. The inclusion of information on the secondary characters (kernel weight, spike length, kernels per spike, and spikelets per spike) in indices did not appreciably increase their predicted efficiencies. Indices designed to improve the aggregate genotype should be effective in developing NDPl as a source of high yielding conventional height lines. If high yielding, high protein semidwarf lines are desired, a desired gain index should be considered for improving NDP1.
Changes in Forage Quality of Improved Alfalfa Populations1
Authors: Demment Montague W. , Teuber Larry R. , Bourque Don P. , Phillips Donald A.
Published: July 2010

Forage yield and forage quality have often been reported to be negatively correlated. African 32 (AF32) and Hairy Peruvian 32 (HP32) alfalfa (Medicago sativa L.) germplasm pools were developed from ‘African’ (AF) and ‘Hairy Peruvian’ (HP), respectively, by two cycles of phenotypic recurrent selection for increased dry weight and increased N concentration. Individual plants were screened by growing them sequentially under N2‐ and NH4NO3‐dependent growth conditions. Because of the relationship between forage yield and forage quality, this study was undertaken to determine the effect of selection under this protocol on forage quality. Glasshouse studies in which the source of N could be controlled showed that 69 to 41% increases in total forage dry matter yield (g plant−l) of HP32 relative to HP on N2‐ and NH4NO3‐dependent conditions were associated with 71 and 36% increases in total digestible dry matter (TIVDDM, g plant−1). The AF32 population increased forage yield and TIVDDM by more than 20% relative to AF under NH4NO3‐dependent conditions, but 9% improvements on N2‐dependent conditions were not significant. Neutral‐detergent fiber, acid‐detergent fiber, and cellulosic fractions were not increased significantly (P < 0.05) in either AF32 or HP32 under either N regime, and in several cases the selected populations had lower concentrations than the original cultivar. Overall marked differences occurred in the manner in which forage quality in the two germplasm sources responded to selection and N‐regime tests. For example, a major improvement occurred in stem quality with selection in AF32 relative to AF, but not in HP32 relative to HP, under the NH4NO3 environment. Combining data from both N environments, much more of the variation in whole‐plant IVDDM (g kg−1) could be attributed to measured parameters in HP, HP32, and AF than in AF32 (92, 91, 89, and 54%, respectively). This study suggests that forage quality can be increased simultaneously with forage yield because, over the range of forage yields studied here, the larger plants did not require a higher proportion of indigestible components to support the additional shoots.
Inheritance of Pubescence in Selected Clones from Two Alfalfa Populations and Relationship to Potato Leafhopper Resistance1
Authors: Elden T. C. , Elgin J. H. , Soper J. F.
Published: July 2010

Intraspecific variation for pubescence occurs in many plant species and has been shown to be associated with insect resistance. The combining ability and heritability of pubescence and its relationship with resistance to the potato leafhopper, Empoasca fabae (Harris), was investigated in progeny from a fixed set of clones in two alfalfa (Medicago sativa L.) populations. The parental material included six clones each from ‘Arc’ and B16 (a synthetic involving two ‘Hairy Peruvian’ plant introductions). All plant material was grown in the greenhouse and resistance was measured using no‐choice laboratory screening techniques. The B16 parent‐clone population means were significantly greater than those for Arc for stem pubescence and lower for number of nymphs and feeding damage. Stem pubescence for the B16 crosses was significantly greater than for the Arc or Arc ✕ B16 crosses. Diallel analyses were performed to detect combining ability effects for density of simple hairs on stems and leaves. General and specific combining ability effects were highly significant for stem and leaf pubescence in all crosses with the exception of a non‐significant specific combining ability effect for stem pubescence in the Arc crosses. Heritability estimates indicated that the density of stem and leaf pubescence can be increased with selection in populations derived from the B16 selected parents. Heritability estimates were nonsignificant for stem and very low (0.28, P<0.05) for leaf pubescence in Arc. Significant negative correlations for all crosses and clones were found between stem pubescence, and both potato leafhopper feeding damage and nymphal populations.
Effect of Genes for Photoperiodism, Semidwarfism, and Awns on Agronomic Characters in a Wheat Cross1
Authors: Knott D. R.
Published: July 2010

The effects of genes for photoperiodism, semidwarfism, and awns on agronomic characters in wheat (Triticum aestivum L.) vary depending on environment. Few data are available for the Canadian prairies. The objective of this study was to measure the effects on wheat of these genes under the long day, short growing season conditions in Saskatchewan and to determine the optimum combination of them. A cross was made between ‘Glenlea’, a photoperiod insensitive, tall, awnletted cultivar, and ‘Era’, a photoperiod sensitive, semidwarf, awned cultivar. A random sample of F6 lines was generated by a single seed descent procedure and tested for response to a 10‐h photoperiod. The results indicated that a single gene was segregating for photoperiod response. Twenty‐four sensitive and 22 insensitive F7 lines plus the parents and another check were tested at Saskatoon in 1983, and Saskatoon and Elrose in 1984. Measurements were made on days to heading, days to maturity, height, straw strength, yield, kernel weight, test weight, protein concentration, and SDS (sodium dodecyl sulfate) sedimentation value. The photoperiod insensitive lines tended to be slightly earlier (0.7 days), shorter (3.7 cm), and lower yielding (2.1%) than sensitive lines. Semidwarf lines were slightly earlier to head (0.5 days) and considerably higher yielding (17%) than tall lines. They also had smaller kernels (1.9 g/1000) and lower protein concentration (0.6 g kg‐1). Awned lines were slightly earlier to head (0.6 days), higher yielding in the two Saskatoon tests (5%) but lower yielding at Elrose (6%), and had larger kernels (1.6 g/1000) than awnletted lines. Protein content was negatively correlated with yield and days to heading was negatively correlated with days to fill. Based on the results of this cross, it appears that to obtain high yield a cultivar should combine semidwarfism, awns, and photoperiod sensitivity.
Selection for Increased Seed Weight in Kleingrass1
Authors: Hussey M. A. , Holt E. C.
Published: July 2010

Selection for increased seed weight was investigated as a potential method for improving seedling vigor and stand establishment characteristic of kleingrass (Panicum coloratum L.). Three cycles of mass selection for increased seed weight were conducted. Selection resulted in a total gain of 53.3% of the mean seed weight of the base population with gains of 27.1,1.8, and 18.5% in Cycles 1 and 2, and 3, respectively. The increased seed weight for Cycles 1 and 2 was attributed to the elimination of light seed weight classes, while increased seed weight in Cycle 3 was due to both the elimination of light seed weight classes as well as to an increase in maximum seed weight. Broad sense heritability estimates declined with selection from 73.2% in Cycle 0 to 41.7% in Cycle 3.
Selection for Time to Maturity in Spring Wheat1
Authors: Wong L. S. L. , Baker R. J.
Published: July 2010

Numerous methods have been used to measure time to maturity in spring wheat, Triticum aestivum L. In this study, the time to complete loss of green color from the spike was used as the basis for evaluating effectiveness of selection for time to maturity and for identifying alternative selection criteria. Time to maturity and 11 other traits were measured on 50 F2‐derived F3, lines in each of six crosses tested in replicated dryland and irrigated field trials. High heritabilities and high genotypic correlations with time to maturity indicated that time to full flag‐leaf emergence, times to beginning or completion of spike emergence, time to anthesis, spike moisture, and number of leaves could be used as selection criteria for time to maturity. Bidirectional selection for time to maturity (10% selection intensity) showed that selection was more effective in some crosses than in others, and under irrigated rather than dryland conditions. Realized heritability for time to maturity varied from −8 ± 21% to 186 ± 50% depending on cross and environment. Bidirectional selection for number of leaves (6% selection intensity) confirmed that this characteristic is a reliable criterion for altering time to maturity. With selection differentials of 0.95 to 2.64 leaves, correlated response for time to maturity varied from 40 to 119 growing degree‐days. Number of leaves and spike moisture concentration are useful methods for evaluating maturity when developmental stages cannot be measured at frequent intervals.
Effect of Altered Intraraceme Competition on Carbon‐14‐Labeled Assimilate and Abscisic Acid in Soybean1
Authors: Spollen W. G. , Wiebold W. J. , Glenn Scott
Published: July 2010

Abscission probability varies among floral positions within soybean [Glycine max (L.) Merr.] racemes. Field (1982, Beltsville silt loam, Typic Fragiudult; 1983, Mattapeake silt loam, Typic Hapludult) grown soybean plants (‘Williams’) were used to determinee the distribution of translocated l4C‐labeled photosynthate and abscisic acid (ABA) among reproductive structures differing for abscission probability. The effect of proximal pods on translocation of 14C‐labeled photosynthate to and ABA concentration in distal pods (floral positions 3 and above) was also evaluated. Treatments consisted of removing or not removing the two proximal pods (floral positions 1 and 2) from the major racemes at nodes 8 and 10 in 1982 and 8, 10, and 12 in 1983. Six days after treatment in 1982 and 12 days after treatment in 1983, 14C‐translocation from the leaf at the node of interest was determined after exposure to 14CO2. On the same day, distal pods were collected for determination of ABA by gas chromatography. For untreated plants, proximal and distal pods accounted for 50 and 7% of the translocated 14C, respectively. Proximal pod removal had no effect on 14C retained by the source leaf (72%) or the concentration of ABA in seeds. Concentration of ABA in pod walls of distal pods was increased by proximal pod removal in only one instance. Amount of 14C translocated to distal pods and distal pod specific activity were not altered by proximal pod removal in 1982 but were increased in 1983. The different treatment effect between years may indicate that distal pods undergo a period of adjustment after proximal pod removal. An understanding of processes that occur during the adjustment period may be necessary before the mechanism of soybean reproductive abscission is known.
Bahiagrass Tetraploids Produced by making (Apomictic Tetraploid ✕ Diploid) ✕ Diploid Hybrids1
Authors: Burton Glenn W. , Hanna Wayne W.
Published: July 2010

A short, rapid spreading hybrid with 30 chromosomes was found among several hundred spaced plants established from seed of a facultative apomictic tetraploid (2n = 40) of bahiagrass (Paspalum notatum Flögge) grown in isolation with a sexual diploid (2n = 20) ‘Pensacola’ bahiagrass clone. This hybrid shed no pollen but set 34% seed when grown next to a large block of Pensacola bahia. Six hundred and forty‐three plants established from open‐pollinated seed of this triploid resulted in 508 maternal triploid plants and 135 40‐ chromosome plants that were similar in appearance but more vigorous than the triploid. It appeared that unreduced eggs from the triploid female united with 10 chromosome male gametes from Pensacola bahiagrass to produce fertile tetraploids. Thus, fertile tetraploid hybrids carrying 20 chromosomes from the apomictic tetraploid and 20 from the sexual diploid were created by hybridization. In the past, such tetraploid hybrids were produced only by doubling the chromosome number in the sexual diploid to make a sexual tetraploid that could then be hybridized with the apomictic tetraploid. The uniformity in the sterile triploids and within the progenies of 117 of the tetraploid hybrids indicated that apomixis had been transferred from the tetraploid parent to its offspring. The variability that occurred in progenies from later harvested seed from 10 of these genotypes indicated that the inherited apomixis was facultative as expected.