bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of a New In Vitro Cell Selection Technique
Authors: Tomaso‐Peterson Maria , Krans J. V.
Published: July 2010

In vitro cell selection is a novel means of recovering elite plant types. This study evaluated a new in vitro cell selection technique [Host‐Pathogen Interaction System (HPIS)] that exposes calli to a pathogen without physical contact between the organisms. The material components that make up the HPIS are a double‐sided petri dish (Lutri‐plate®), a polycarbonate Nucleopore® membrane, caulking cord, and the appropriate agar media. Callus of ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.) and two isolates of Rhizoctonia solani Kuhn. (RVPI and RATCC) were used in evaluating the HPIS. After 12 d of coculture in the HPIS, callus fresh weights were less in plates cocuitured with RVPI (−0.09 g) and RATC(C0 .47 g) isolates than control plates (0.95 g). Callus cocuitured in the HPIS with either isolate displayed no plantlet formation, while control callus cultured in the HPIS without the fungi formed numerous vigorous plantlets. The HPIS appears to provide an effective means for exposing calli to a pathogen without the complications associated with direct physical contact between the organisms. Research is currently underway to utilize the HPIS for recovering desirable variants of Penncross with resistance to R. solani.
Membrane Thermostability and Heat Tolerance of Spring Wheat
Authors: Shanahan J. F. , Edwards I. B. , Quick J. S. , Fenwick J. R.
Published: July 2010

Spring wheat (Triticum aestivum L.) is a major crop of the northern Great Plains. High temperature stress during the grain‐fill period is a major constraint to increased productivity of spring wheat, particularly in the southern part of the region. The electrolyte leakage or membrane thermostability (MT) test was conducted at anthesis on flag leaves of eight field‐grown genotypes of spring wheat and the results related to the yield of those genotypes grown at three other field locations. Genotypes were derived from two crosses involving parents adapted and unadapted to the region or thermal aspects of the climate. The three field locations represented northern, central, and southern areas of the northern Great Plains with soil classifications of Aeric Calciaquoll, Aeric Calciaquoll, and Typic Haplustoll, respectively. Based on MT values, genotypes were grouped as heat‐tolerant (HT, n = 4) vs. heat‐sensitive (HS, n = 4). The HT and HS genotypes produced similar grain yields at the northern and central locations. However, the HT group of genotypes produced 21% more grain yield (4.28 Mg ha−1) than the HS group (3.55 Mg ha−1) at the southern site, which was considerably warmer during the grain‐fill period than the other two locations. Average temperatures during July were 19.5, 21.7, and 23.4 °C at the northern, central, and southern locations, respectively. Based on results of this study it seems that the MT test is a useful screening procedure for selecting HT genotypes of spring wheat.
Inheritance of and Selection for Panicle Exsertion in Semidwarf Oat
Authors: Farnham M. W. , Stuthman D. D. , Pomeranke G. J.
Published: July 2010

Incorporation of the dwarfing gene Dw6 into most oat (Avena sativa L.) backgrounds results in a plant of semidwarf height with a panicle that does not exsert from the flag leaf sheath. Since panicle exsertion is important to obtain high yield, this research was conducted to: (i) determine if two known sources of panicle exsertion designated fatua and sterilis are genetically distinct, (ii) evaluate effectiveness of selection for panicle exsertion, and (iii) determine if selection for exsertion causes correlated responses in other traits. Segregation for exsertion was evaluated in the F2 of testcrosses between fatua‐ or sterilis‐derived exserted semidwarf lines and the nonexserted semidwarf ‘Echidna’ and in the F2 of intercrosses between the fatua and sterilis source lines. The F2 plants were selected, based on their level of panicle exsertion, under two selection schemes, stratified random and divergent. In the stratified scheme, the effect of incremental selection on progeny expression was evaluated in the F3 and F4. The effectiveness of divergent selection was evaluated in the F3. Sterilis testcrosses exhibited unimodal F2 distributions for panicle exsertion while fatua testcrosses and the intercrosses were bimodal. Parent‐offspring regressions of exsertion values from stratified selections gave coefficients (b) ranging from 0.50 to 0.70 cm cm−1 for F2‐F3 combinations. Realized heritability estimates were similar for both positive and negative divergent selection and ranged from 0.47 to 0.75. Fatua and sterilis sources of panicle exsertion appear to be conditioned by different genes. Increases in exsertion due to selection were highly correlated with increases in peduncle length.
Effectiveness of Fruiting Sites in Cotton: Yield
Authors: Jenkins Johnie N. , McCarty J. C. , Parrott W. L.
Published: July 2010

The fruiting sites at which cotton, Gossypium hirsutum L., plants set bolls that are harvested influence how well the plants tolerate insects. The objective of this research was to determine the fruiting patterns of eight cultivars of cotton in terms of fruiting sites of harvestable bolls when planted in a conventional pattern of rows spaced 1‐m apart with a plant population of approximately 95 000 plants ha−1 for 2 yr in Mississippi. Descriptive terms are defined as follows: (i) sympodium—a fruiting branch; (ii) monopodium—a vegetative branch; (iii) node—the place on the main stem where sympodia monopodiarise, we numbered the nodes beginning with the cotyledeonary node as number one; (iv) position—refers to the order which buds (potential bolls) are produced on a sympodinm branch; and (v) fruiting site—any specific node‐position combination. Cultivars compared and their release dates were: Stoneville 213, 1962; Stoneville 506, 1980; Stoneville 825, 1979; Tamcot CAMD‐E, 1979; Deltapine 50, 1984; McNair 235, 1975; DES 119, 1986; and Deltapine 20, 1985. Bolls at position one on sympodial branches produced 66 to 75% of total yield; those at position two produced 18 to 21%; all other positions on sympodial branches produced from 2 to 4% of total yield. Monopodial branches produced from 3 to 9% of the total yield. Sympodial branches from Nodes 9 through 14 produced the bulk of the lint in all cultivars. Distribution of lint over sympodia among cultivars was significantly different for positions one and two, with the newer, early maturing cultivars producing significantly more lint from sympodial branches at Nodes 6 through 8 than the older cultivar Stoneville 213. Tamcot CAMD‐E, McNair 235, and Deltapine 20 also produced less lint on monopodial branches than Stoneville 213. This research provides valuable information needed to more effectively manage the production of the newer, early maturing cuitivars of cotton presently being grown in the mid‐South.
Immature Fiber Mutant of Upland Cotton
Authors: Kohel R. J. , McMichael S. C.
Published: July 2010

The inheritance of a mutant character of Upland cotton, Gossypium hirsutum L., that results in abnormal fiber development is described, and the mutant is compared to environmentally induced immature fiber. The phenotype and fiber properties of the mutant resemble those found in bolls that have experienced arrested development due to environmental conditions. Seed of the mutant plants however, showed normal development. The mutant expression was conditioned by homozygous recessive alleles at a single locus and assigned the gene symbol im.
European Corn Borer Resistance and Cell Wall Composition of Three Maize Populations
Authors: Buendgen M. R. , Coors J. G. , Grombacher A. W. , Russell W. A.
Published: July 2010

Feeding activities of herbivorous insects are influenced by host plant nutritional quality. Improved insect resistance resulting from either natural or artificial selection may be due, in part, to changes in nutritive constituents of plants. The first objective of this study was to measure changes in detergent fiber, lignin, ash, and N concentrations in whorls, leaf‐sheaths, and stalks of the BS9 maize (Zea mays L.) population across five cycles of selection for resistance to the European corn borer (ECB) [Ostrinia nubilalis (Hübner)]. The second objective was to evaluate ECB resistance in the WFISIHI and WFISILO maize populations, which were developed for high and low concentrations, respectively, of indigestible plant constituents (acid detergent fiber, lignin, and silica) in the leaf sheath. Leafsheath composition for all five cycles of BS9 was measured in three environments in Iowa. Whorl, leaf‐sheath and stalk composition, as well as first‐ and second‐generation ECB resistance of populations WFISIHI, WFISILO and Cycles 0, 2, 4, and 5 of BS9 were evaluated in two environments in Wisconsin. Whorl composition was not related to changes in ECB resistance in anypopulation. In BS9, leaf‐sheath and stalk concentrations of neutral and acid detergent fiber, cellulose, and lignin increased linearly over selection cycles. In contrast, WFISIHI was as susceptible to second‐generation ECB as WFISILO, suggesting that the responses in BS9 may be due to linkage or unintentional selection. Populations BS9, WFISIHI, and WFISILO, however, were derived from diverse sources, and it is likely that mechanisms for resistance differ for the three populations.
Natural and Mass Selection for Improving Strawbreaker Foot Rot Resistance in Winter Wheat
Authors: Roberts D. E. , Allan R. E.
Published: July 2010

Selection in wheat (Triticum aestivum L.) for resistance to the Strawbreaker foot rot pathogen, Pseudocercosporella herpotrichoides (Fron) Deighton, involves either microscopic techniques or examination of individual tillers—slow and laborious methods. Natural and mass selection techniques were examined as potentially simpler alternatives. Eight F2 populations of winter wheat having strawbreaker resistance genes derived from Aegilops ventricosa Tausch were exposed to pressure from the Strawbreaker fungus in field experiments during two seasons. After two cycles of natural selection and two cycles of divergent mass selection for seed size, F2, F3, and F4 populations were evaluated in a third season for mean performance of several agronomic traits, including reaction of individual plant stems to Strawbreaker. The F5 seedlings of four populations from the mass selection experiment were assayed for an endopeptidase isozyme linked to the Ae. ventricosa Strawbreaker resistance gene. Plants homozygous for the isozyme increased in frequency in two populations. Natural selection and mass selection for seed size favored primarily non‐semidwarf and vigorous plants, respectively, that were generally susceptible to the disease. These results suggest that populations heterogeneous for non‐semidwarf and semidwarf genes are unsuitable for exposure to the Strawbreaker fungus, under natural or mass selection, in early generations. As an alternative, single‐seed descent should maintain variability while attaining homozygosity for height and Strawbreaker resistance. Severe disease pressure applied to near‐homozygous populations should reduce the frequency of susceptible plants. Resistance could then be confirmed by endopeptidase assay, and breeding lines developed that are homozygous for the semidwarf and strawbreaker‐resistant characters.
Grain Filling in Three Spring Wheat Genotypes: Statistical Analysis
Authors: Darroch B. A. , Baker R. J.
Published: July 2010

Final grain weight, a component of grain yield in spring wheat (Triticum aestivum L.), is dependent on the rate and duration of the grain filling process. Duration of grain filling also affects time to maturity. This study was undertaken to examine grain weight in relation to rate and duration of grain filling in three spring wheat cultivars (Neepawa, Fielder, and HY320) and to develop statistical methods for comparing grain filling curves. Four field trials were conducted at Saskatoon, SK, Canada, in 1986–1988. Wheat spikes were collected twice weekly from each plot to determine average grain dry wt. The relationship between grain weight and accumulated growing degree‐days (GDD) from anthesis was described a logistic equation. Final grain weight, and rate and duration of grain filling, were calculated from the fitted curves. Univariate and multivariate analyses of variance were used to examine cultivar differences in grain filling. Stepwise multivariate analysis of variance indicated that maximum grain weight was the most important parameter in characterizing the grain filling curves of the cultivars studied. HY320 had the largest grains (37.0–48.2 mg) in all four experiments and, except in 1986, Neepawa had the smallest grains (29.0–34.8 mg; 36.5 mg in 1986). HY320 had the highest rate grain filling (0.129–0.146 mg/GDD) and Neepawa the lowest (0.096–0.122 mg/GDD) in all experiments. Differences in duration of grain filling were not consistent. Multivariate analysis of variance proved to be a useful tool in examining grain filling curves.
Diallel Analysis of Relative Growth Rates in Maize Synthetics
Authors: Nevado M. E. , Cross H. Z.
Published: July 2010

Previous studies indicated that relative growth rates (RGR) based on easily obtained measurements [(leaf number ✕ leaf length ✕ leaf width ✕ O.5)/days to silking] hold promise as a selection tool to increase grain yields in early‐maturing maize (Zea mays L.). The objective of this field research was to evaluate the interrelationships among RGR, grain yield, yield components, and components of RGR. Three independent diallel sets among eight parental synthetics were evaluated in up to nine environments during 3 yr. General combining ability (GCA) and specific combining ability (SCA) effects were estimated using Griffing's Method 4, Model 1. Correlations among GCA effects (rA) for all traits were obtained. Mean squares for GCA were highly significant for all traits in one or more of the diallels, while SCA effects were significant in 50% of the F‐tests. The relative magnitudes of ratios ef the GCA component to GCA pros SCA components (mean squares) suggested that it should be easier to select parents of high‐performing progenies for kernel row number, kernel weight, RGR, leaf length, and silking date than for kernels per row or grain yield. Correlations among GCA effects estimated across environments for three diallels among eight synthetics indicated that GCA effects for RGR were highly correlated (rA = 0.82) with GCA effects for grain yield. Highly significant correlations among GCA effects for RGR, ears per plant, and kernels per row (primary yield components), as well as highly significant correlations among GCA effects for yield and leaf number, leaf length, and days to silking (RGR components), indicated that these traits are not independent. Results confirmed the suggestion that selection for increased RGR would increase grain yields in early maize.
Seeding Rates for Hill Plots in Oat
Authors: McFerson J. K. , Frey K. J.
Published: July 2010

Hill plots are used extensively for testing small‐grain lines in early generations when seed supplies are limited and large numbers of genotypes must be evaluated. Hill plots and multiple‐row plots estimate the value of a genotype similarly, yet little is known about the effects of seeding rate on performance of cereal genotypes in bills. We evaluated 30 oat (Avena sativa L.) genotypes for grain and protein yields, heading date, plant height, and groat protein concentratian in hill plots with seeding rates of 5, 10, 15, 20, 25, and 30 seeds per hill (equivalent to 18, 36, 54, 71, 88, and 106 kg ha‐1). In another set of treatments, barley (Hordeum vulgare L.) was sown with the five lowest oat seeding rates so that all hills were planted with 30 seeds. It was intended that the barley plants would mimic the competitive effects of oat plants at the standard seeding rate of 30 seeds per plot. The experiment was grown in a split‐plot design at two locations for 2 yr. Significant differences existed among seeding rates for all traits, but most seeding rates ranked the 30 genotypes in similar order. The use of barley to mimic the competitive effect of oat at the standard sowing rate was successful, but the extra cost of using this technique is not justified. Seeding rates for oat as low as 20 seeds per plot did not affect trait expression or genotypic rankings, and it requires one‐third fewer seeds. A reduction in seeding rate will permit small grain breeders to expand their breeding operations to include schemes such as early generation recurrent selection.
Selection for High Specific Gravity in Oat Populations Heterogeneous for Naked Genotypes
Authors: Lanini Brenda J. , Marshall H. G.
Published: July 2010

The nutritive value of oat (A vena sativa L.) grain could be improved by the development and use of naked‐seeded cultivars of A vena nuda L. Hulled types predominate in heterogeneous populations during generations of inbreeding, and this reduces the effective population size for selection of superior naked genotypes. Our objectives were to apply repeated cycles of selection for high specific gravity seed to bulk populations and determine the effects on the percentage of naked seed, grain test weight, and average groat weight. A specific gravity grader was used to apply two cycles of selection pressure to four bulk populations that were relatively homozygous (F6 to F8) but heterogeneous for the N gene (naked seed), as well as a fifth population homozygous for that gene. The original (0) and derived subpopulations were compared in replicated 5‐row plots in a split‐plot design near University Park, PA, during 1985. Increases in the amount of naked seed ranged from 23 to 134% above the 0 populations after one cycle of selection. With the exception of Population 5, a second cycle further increased the percentage of naked seed to amounts ranging from 25 to 209% above the 0 populations. Each cycle of selection increased grain test weight of all populations except Population 5, where two cycles were required to increase the trait. One cycle of selection did not change groat weight, but there was 3.9% increase after two cycles of selection. Natural selection caused significant decreases in the percentage of naked seed in four of the populations (15 to 35%), but other traits were not affected. In conclusion, selection for high specific gravity separated naked from hulled seeds and rapidly increased the frequency of naked‐seeded plants in oat populations that were heterogeneous for the N gene.
Corn, Sorghum, and Soybean Response to Irrigation in the Mississippi River Alluvial Plain
Authors: Heatherly Larry G. , Wesley Richard A. , Elmore C. Dennis
Published: July 2010

The most agronomically efficient use of irrigation water is for those crops that give the greatest response. In the Mississippi River alluvial plain, the primary irrigated crop is soybean [Glycine max (L.) Merr.], but the response of soybean to irrigation has not been compared to that of other crops. Irrigated and nonirrigated experiments were conducted from 1984 through 1987 on Tunica clay (clayey over loamy, montmorillonitic, nonacid, thermic Vertic Haplaquept) to determine the effect of irrigation on field‐grown corn (Zea mays L.), sorghum [Sorghum bicolor (L.) Moenchl, and soybean yield and yield components. Shifts in weed species composition resulting from continuous monocropping with these crops also were quantified. Irrigation was applied from beginning bloom to near matarity of each crop whenever soil water potential at the 30‐cm soil depth averaged about —70 kPa. Irrigation did not consistently affect weed cover in any of the crops. Weed level differences among crops resulted from different weed control programs for each continuous cropping system. Differences between average seed yields of irrigated (I) and nonirrigated (NI) corn, sorghum, and soybean 2886, 694, and 1574 kg ha‐1, respectively. Sorghum produced the most stable nonirrigated yield and the smallest increase in monetary return from irrigation. Differences between I and NI corn and soybean yields were associated with increased number of seed. Smaller sorghum yield differences were associated with differences in seed weight or a combination of differences in seed weight and number of seed. Across the 4 yr, irrigation of corn and soybean produced nearly equal increases in gross income per unit of land area, but irrigation efficiency for soybean was lower because achieving the increased return from irrigation required nearly twice as much water for soybean as for corn.
Testing Mean Stage as a Predictor of Alfalfa Forage Quality with Growth Chamber Trials
Authors: Fick Gary W. , Janson C. Garth
Published: July 2010

Estimation of alfalfa (Medicago sativa L.) forage quality as the crop grows in the field provides useful management information. The quantified morphological stage of development defined by mean stage by weight (MSW) can be used to estimate crude protein (CP), in vitro true digestibility (IVTD), neutral‐detergent fiber (NDF), acid‐detergent fiber (ADF), and acid‐detergent lignin (ADL) of standing crop. The purpose of this study was to validate previously published prediction equations for CP, IVTD, NDF, ADF, and ADL based on MSW, including evaluation of general robustness and potential bias in prediction equations. Nine combinations of growthchamber environment and plant age were used to develop a data set independent of the prediction equations to be tested. The tests consisted of linear regression of growth‐chamber observations on predicted values. Prediction errors were ≤39 g kg‐1 of dry matter for all parameters, and all coefficients of determination were ≥0.61. These compare favorably to calibration statistics for the prediction equations and indicate that MSW is a robust basis for predicting alfalfa forage quality. However, most intercepts and slopes of the linear regressions deviated from 0.0 and 1.0, respectively, indicating bias in model predictions. Therefore, prediction equations should be recalibruted so that the calibration data and the predictive domain overlap as much as possible.
Paired Rhizobia General and Specific Effects on Subterranean Clover Seedling Growth
Authors: Rumbaugh M. D. , Lawson K. L. , Johnson D. A.
Published: July 2010

The relationships among rhizobial strains and their interactions with genetically different legume cultivars should be evaluated before formulating and producing inocula. Diallel analysis procedures were used to compare the performance of one‐ and two‐strain Rhizobium leguminosarum biovar trifolii inocula and to quantify the general and specific interaction effects of the strains on seedling growth of subterranean clover Trifolium subterraneum L. subsp. subterraneum and subsp. brachycalycinum Katzn. and Morley). Ten isolates of rhizobia from the Mediterranean Region were tested as one‐ and two‐strain inocula on three cultivars of subterranean clover grown in tube culture. Two‐strain inocula were 2.5% superior to onestrain inocula in increasing clover shoot weight and 2.4% superior in increasing effectiveness of N2 fixation when evaluated for three cultivars. Except for root weight and the number of nodules per plant, the general effects of strains were approximately twice as important as their interaction effects. Rhizobial strain performance was not consistent among the three clover cultivars. Diallel analysis procedures appear to offer promise in quantifying the relationships between legume‐Rhizobium combinations and in identifying the most beneficial host‐strain combinations for maximizing N2 fixation. A two‐stage screening process for inocula development was suggested. Preliminary tests to select strains of high average effectiveness should be followed by diallel performance trials with several cultivars to choose two‐strain combinations having high positivespecific interaction effects. One or more two‐strain combinations might be used in mixed strain inocula with confidence that they should perform well if sufficiently competitive with indigenous rhizobial populations.
Seed Priming Influence on Germination and Emergence of Pepper Seed Lots
Authors: Bradford Kent J. , Steiner Jeffrey J. , Trawatha Susan E.
Published: July 2010

Seed priming can markedly increase the germination rate of pepper (Capsicum annuum L) seed, but has not always been accompanied by improvements in field emergence rates or percentages. Furthermore, optimal priming conditions may vary among cultivars and even seed lots of a given species. The objective of this study was to evaluate the influence of a standard seed priming procedure on the laboratory germination and field emergence of a large number of pepper seed lots. Forty‐two (1986 study) or 30 (1987 study) lots of ‘Yolo Wonder’ and ‘Anaheim’ pepper (all >80% viability) were primed for 7 d at 25 °C on blotters saturated with 30 g KNO3 kg‐1 H2O solution, rinsed, and dried. Control (untreated) and primed seeds were then germinated in the laboratory at 20 °C or planted in field emergence trials at two locations (Davis and Fresno, CA) in yr. Priming slightly reduced final laboratory germination percentages, but also decreased the mean times to germination (MTG) 71 to 78%. Field emergence percentages generally were unaffected by priming, but mean times to emergence (MTE) were reduced 8 to 29%. There was a strong interaction between seed lots and priming response, with the slowly germinating lots exhibiting the greatest benefit from priming. In both the laboratory and field, the reduction in time to germination or emergence due to priming was linearly related to the initial MTG or MTE. A quadratic relationship between the MTG and MTE of control seeds extrapolated through the same data for primed seeds. Thus, while laboratory germination percentages were a relatively poor predictor of field emergence percentages for these relatively high‐quality seed lots, laboratory MTG was highly correlated with field MTE in two of three field trials. Although seed lots differed in the magnitude of their response to a standard priming treatment, all lots exhibited markedly improved rates of germination and emergence after priming.
A Device for Grinding Cereal Crowns
Authors: Livingston David P.
Published: July 2010

Currently available tissue grinders effectively grind most soft plant tissue such as leaves and stems. However, none of the devices tried in this laboratory would adequately grind fresh cereal crown tissue. A device made from stainless steel and mounted in a commercial hand drill is described. This device will rapidly grind fresh crown tissue and is easily cleaned between samples.
Salinity Tolerance in Sorghum. I. Whole Plant Response to Sodium Chloride in S. bicolor and S. halepense
Authors: Yang Y. W. , Newton R. J. , Miller F. R.
Published: July 2010

Based on casual qualitative observations, grain sorghum [Sorghum bicolor (L.) Moench[ is less tolerant to salt than the noxious weed and potential biomass energy crop, johnsongrass [S. halepense (L.) Pers.]. The objective was to quantitatively compare whole plant growth and physiological responses to salt stress of these two sorghum species. Salt stress was induced by adding incremental levels of NaCI to a vermiculite medium until concentrations of 0.1 and 0.2 M were attained. Leaf number and leaf area reduction and dry weight reduction in the culm and leaves in response to salinity compared to controls were greater in S. bicolor than in S. halepense. Larger leaf growth reductions in response to salinity in S. bicolor were associated with higher tissue levels of Na and CI. Sorghum halepense had a lower Na/K ratio in the leaves as well as in the roots; the cuim ratio was the same in both species. Higher ψp (0.65 MPa) and lower ψs(−2.17 MPa) S. bicolor leaves compared to the ψp (0.28 MPa) and ψs (−1.71 MPa) S. halepense leaves indicated more osmotic adjustment and more turgor maintenance in S. bicolor than in S. halepense; this response was due largely to CI and sucrose accumulation. The greater growth reduction observed in S. bicolor was associated with higher levels of CI higher Na/K ratios, and a greater capacity for osmotic adjustment. A Na exclusion mechanism appeared to be operative in both species but was more apparent in S. halepense.
Ground Cover Potential of Forage Grass Cultivars Mixed with Alfalfa at Divergent Locations
Authors: Casler M. D. , Walgenbach R. P.
Published: July 2010

Forage grass cultivars are often grown in binary mixtures with forage legumes. Because performance of grass‐legume mixtures cannot be reliably predicted from pure stand information of the components, testing of grass‐legume mixtures is necessary to develop reliable mixture recommendations. The objectives of this study were to evaluate a large number of cultivars of several temperate forage grasses in binary mixtures with alfalfa (Medicago sativa L.) for ground cover potential in a range of Wisconsin environments, and to develop an efficient cultivar screening program. Cultivars of nine species (146 total cultivars) were grown in at least one of five experiments. Experiments were seeded in spring of 1985 and 1986 at one of four locations divergent in both soil type and latitude. Grass persistence was determined after three growing seasons by evaluating the percentage of ground cover remaining. Grass species and genera varied in percentage ground cover, but were subject to interactions with years and locations. In general, orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) had the highest ground cover (76%). Variation in ground cover among cultivars was detected in all species except diploid perennial ryegrass (Lolium perenne L.), tetraploid intermediate ryegrass (L. hybridum), and festulolium (Festulolium braunii K.A.). Cultivars interacted with locations and/or years for all species, except reed canary grass (Phalaris arundinacea L.). Cultivar ✕ location interactions appeared partially due to latitude for smooth bromegrass (Bromus inermis Leyss.), tall fescue, and most ryegrasses, and to soil type for timothy (Phleum pratense L.). Conclusions regarding the development of a cultivar testing program differed for most species. A reasonable compromise in Wisconsin, to allow for testing each species in common trials, would be to select one southern and one northern test site.
Crop Effects on Genetic Relationships Among Sugarcane Traits
Authors: Milligan S. B. , Gravois K. A. , Bischoff K. P. , Martin F. A.
Published: July 2010

Genetic correlations are commonly considered in the development of selection strategies. Previously reported correlations between sugarcane (Sacdmrum spp.) yield components may be of questionable value because they were obtained either from small populations or from a restricted range of environments. The effect of crop age on trait relationships has not been reported. Thistady's objective was to examine crop age effects on the geneticorrelations among sugarcane traits using path coefficient analysis. A population was planted in 1983 and 1984 at five locations in Louisiana. Harvest data were collected for three crops. Results indicated that cane yield (TCH) was the most important determinant of sucrose yield (SPH) and became increasingly important in determining the SPH in older ratoon crops (rsph,tchh = 0.91). Stalk number (SNO) was the primary determinant of TCH and became more important in determining TCH in older ratoon crops (rtch,sno = 0.77). Stalk diameter (DIA) was more important than stalk length (LEN) and stalk density (DEN) in affecting stalk weight (WT) regardless of crop age (rwt,dla = 0.70 vs. rwt,len = 0.52 and rwtden = 0.33). Brix and juice parity were highly correlated with sucrose content and with each other, and were not affected by crop age. The results indicated that selection for SPH should emphasize TCH with concentration on SNO, particularly in ratoon crops. The results also indicated that development of selection strategies of sugarcane should consider crop age in weighing the importance of yield components that affect SPH.
Variation and Covariation in Stover Digestibility Traits in Diallel Crosses of Maize
Authors: Dhillon B. S. , Paul Chr. , Zimmer E. , Gurrath P. A. , Klein D. , Pollmer W. G.
Published: July 2010

In the cooler regions of the world, the area under forage maize (Zea mays L.) production has increased, and breeding for digestibility has gained importance. This study was conducted on digestibility traits of stover in maize forage, to determine variation, as analyzed by the combining‐ability approach, and correlation coefficients (r) in these traits and r between these and dry matter (DM) yield traits. Diallel crosses among 12 inbred lines were evaluated at silage and grain harvests for 2 yr at two agro‐climatically diverse locations in West Germany. Stover samples were analyzed for in vitro digestible organic matter (IVDOM), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) using laboratory and near infrared reflectance spectroscopy (NIKS) methods. Mean squares due to general (GCA) and specific combining ability (SCA) and their interactions with environments (GCA ✕ E, SCA ✕ E) were, for the most part, significant. At silage harvest, GCA was the most important source of variation in all traits, followed by SCA ✕ E interactions. At grain harvest, GCA and SCA ✕ E for IVDOM and ADL and SCA ✕ E for NDF and ADF accounted for larger variability than SCA and GCA ✕ E. The genetic ratio indicating the relative importance of GCA vs. SCA was > 0.81 in all cases, except that it ranged from 0.40 to 0.58 for NDF and ADF at grain harvest. The IVDOM had negative r with NDF, ADF, and ADL, and r values were stronger at silage harvest; IVDOM was not correlated with stover DM yield, and had negative r with ear DM yield. The results showed significant genotypic variation for several traits, with GCA the most important source of variation for most traits, and showed that selection for digestibility should preferably be made at the ensiling stage.
Role of Carbohydrates in Desiccation Tolerance and Membrane Behavior in Maturing Maize Seed
Authors: Chen Yuguang , Burris Joseph S.
Published: July 2010

Seed corn (Zea mays L.) ears harvested at seed moisture contents greater than 400 g H2O kg−1 fresh wt. (fw) are sensitive to rapid, high‐temperature (45–50 °C) drying, but tolerant to low‐temperature drying. A preconditioning process that precludes this injury without major moisture loss was used to study the nature of the drying damage and the role of soluble sugars in membrane stabilization during drying of two seed corn hybrids. Ears were harvested at moisture contents of 550, 450, and 400 g H2O kg−1 fw, and preconditioned at 35 °C for 6 to 48 h before drying at 50 °C. Seed germination was correlated with leachate conductivity (r = −0.79) and sugar leakage (r = −0.80) after different times of preconditioning indicating the involvement of membrane function in the damage caused by high temperature drying. Total soluble‐sugar concentration decreased during preconditioning with no significant change individual monosaccharide content. The percentage composition of sucrose and a larger oligosaccharide, raffinose, increased significantly during preconditioning. The high correlations between raffinose/sucrose and warm germination, conductivity, and sugar leakage (r = 0.83, −0.80, and −0.71 for A632, and 0.89, −0.78, and −0.79 for B73, respectively) indicates the added effect of raffinose on induced protection. These results suggest that soluble‐sugar compositional relationships rather than absolute content may play an important role in membrane stabilization. The presence of raffinose at certain levels also may be a key factor in protecting maturing seeds from high temperature drying damage. The results also indicate that the transition from desiccation intolerance to tolerance is metabolic and not necessarily related to moisture loss.
Inheritance of Traits Associated with Grain Yield in a Spring Oat Diallel
Authors: Kolb F. L. , Marshall H. G. , Hill R. R.
Published: July 2010

Developing oat (Avena sativa L.) cultivars with superior grain yield potentials is difficult. Our objectives were to characterize traits associated with high grain yield of elite genotypes and to determine their inheritance and potential value for selection. Three extremely high yield (HY) genotypes (‘Ogle’, ‘Orbit’, and ‘Hazel’) and three moderate yield (MY) genotypes (‘Dal’, PA2250, PA12422) were crossed in diallel combinations. Data were collected on parents and F2 progenies in the field during 1985 and on parents and F3 lines in 1986. The HY genotypes were always superior for seed weight and usually superior or equal to the MY genotypes for tiller production, harvest index (HI), and biological yield. In the F2, HY progenies were always superior or equal to MY progenies for most traits measured. Additive genetic effects were most important for all traits, and except for tillers/plant, nonadditive effects also were significant. In the F3, large, significant additive genetic effects occurred for most traits. Nonadditive effects also were significant for seed weight, grain yield, biological yield, and HI, with an important specific combining‐ability component for the latter three. All significant correlation coefficients between traits of F2 plants and F3‐derived lines were small, and multiple regression models based on F2 traits were not useful for predicting F3 line yields. Since additive genetic effects for yield‐related traits were large, however, some progress should result from early generation selection for those traits.
Vasculature of Soybean Racemes with Altered Intraraceme Competition
Authors: Wiebold W. J. , Panciera M. T.
Published: July 2010

Abscission probability differs among floral positions within soybean [Glycine max (L.) Merr.] racemes, with proximal flowers much less likely to abscise than distal flowers. The objectives of this research were to measure phloem and xylem areas within the rachises of developing soybean racemes, to determine if the sizes of the vascular tissue areas were associated with flower abscission and pod development, and to determine if removal of proximal pods affects vascular tissue areas in distal regions of the racemes. ‘Williams 82’ soybean plants were grown in the field in 1985 and 1986 and tagged when the flower at raceme position 1 (most proximal) opened. In 1985, racemes were harvested 8 and 16 d after tagging (DAT). Reproductive structures were removed, dried, and weighed. The remaining rachises were fixed, dehydrated, embedded in paraffin, serially sectioned, and stained. In 1986, proximal pods (positions 1 and 2) were removed from one‐half the racemes 7 DAT. Fourteen and 21 DAT, treated and control racemes were harvested and treated as described for 1985. Distal pods were smaller than proximal pods at both harvests in both years. Distal internodes contained smaller phloem and xylem areas than proximal internodes, but phloem and xylem tissues were present in the most distal region of the rachis. Removal of proximal pods at 7 DAT increased distal pod weight, phloem and xylem areas, and ratio of phloem to xylem area 21 DAT. Vascular tissue expansion between 8 and 16 DAT was faster in rachis internodes 1 through 3 than in internode 4. Abscission probability was lower for proximal flowers than distal flowers. High abscission probabilities and slow pod growth were associated with a region of the raceme with small vascular tissue areas and slow vascular area expansion rates. The mechanism that inhibits growth and development of tissues within the distal region of the raceme may also influence abscission.
Defferential Agronomic Response of Winter Wheat Cultivars to Preanthesis Environmental Stress
Authors: Entz M. H. , Fowler D. B.
Published: July 2010

Winter wheat (Triticum aestivum L.) cultivars produced in the semiarid environment of the Canadian prairies are subjected to variable water stresses. Therefore, successful cultivars in this region require both a high production potential and yield stability. This study was initiated to compare the agronomic performance of two winter wheat cultivars that had demonstrated a differential response to the often high drought stress environment of Saskatchewan. Eleven field trials were conducted at seven locations in Saskatchewan from 1984 to 1987. Measurements included dry matter production, yield components, grain yield, harvest index, water use, and water use efficiency. Pan evaporation during the 15‐d period immediately prior to anthesis (E) ranged from 64 to 158 mm for the 11 trials and was used as an indicator of environmental stress. There was a significant (P < 0.01) negative relationship between grain yield and E for both cultivars. The difference in grain yield between cultivars (Norwin minus Norstar) ranged from approximately 500 to −1500 kg ha−1. As stress increased, the grain yield for Norwin declined at a significantly higher rate than that of Norstar. The differential response of these cultivars to stress was related to differences in kernel number m−2 (KNO). Under high E (approximately 8.0 mm d−1), KNO for both cultivars was associated with preanthesis dry matter production. Under low E (approximately 5.0 mm d−1), significantly higher KNO for Norwin was attributed to a more favorable preanthesis dry matter distribution (KNO per unit of aerial dry matter present at anthesis) compared to Norstar. Other factors that contributed to the observed genotype by environment interaction were harvest index and water use efficiency (kg grain ha−1 mm−1 evapotranspiration).
Fall Dormancy Response of Alfalfa Investigated with Reciprocal Cleft Grafts
Authors: Heichel G. H. , Henjum K. I.
Published: July 2010

Control of the fall dormancy response in alfalfa (Medicago sativa L.) has been associated with cool temperatures and short days typical of autumn, but the physiological bases of the phenomenon are poorly understood. The purpose of these glasshouse and growth chamber investigations was to develop a model system based on reciprocal cleft grafts between shoots and roots of contrasting cultivars to determine whether a specific graft component is associated with the dormancy response and whether graft‐transmissible factors might be implicated in the response. The experimental approach involved reciprocal cleft grafts between fall‐dormant ‘Norseman’ and fall nondormant ‘African’. The degree of prostrate growth of the canopy (as height‐to‐width ratio), mean internode length, mean area per leaf, herbage dry weight, and crown freezing tolerance of various graft combinations were measured. The ratio of canopy height to width, mean internode length, and mean area per leaf were primarily determined by the genotype of the shoot plus crown, with mediation by root genotype. In contrast, herbage production per plant indicated that the fall‐dormant member of the grafted plant conditioned herbage growth regardless of whether fall dormancy was a characteristic of the shoot genotype or the root genotype. The results further indicate that one or more graft‐transmissible factors may be involved in the fall dormancy response. This model system provides an approach to implicate specific plant organs in the fall dormancy response of alfalfa, and may provide new insights for investigating the metabolic and genetic basis of fall dormancy.
A Controlled‐Temperature Rhizotron
Authors: Bland William L. , Mesarch Mark A. , Wolfe June E.
Published: July 2010

Growth of roots deep in the soil profile often is essential for continued water uptake by dryland crops in subhumid climates. Study of root growth in these situations must be conducted in field‐scale volumes of soil, to allow normal plant development. Additionally, given the importance of temperature to all biological processes, the thermal regime of field soil should be adequately mimicked. We have constructed a rhizotron that meets these criteria. Nine cylinders 0.45 m in diameter and 1.8 m high were fabricated from plastic sewer pipe. Controlled‐temperature water is circulated through plastic tubing embedded in the soil media and wrapped around the columns. Vertical temperature gradients of 15 °C m−1 can be created with horizontal variations of less than 0.4 °C. Diurnal fluctuations in temperature can be produced in the top 0.15 m. Root growth is monitored with root observation tubes installed horizontally at 0.3‐m intervals. Soil volumetric water content is measured by time‐domain reflectometry.
Maturity Genotype of ‘Mukden’ Soybean
Authors: Buzzell R. I. , Saindon G. , McBlain B. A. , Bernard R. L.
Published: July 2010

A field test procedure using soybean [Glycine max (L.) Merr.] maturity isolines has indicated that ‘Mukden’ is of the genotype e3e3, whereas the delayed flowering response of Mukden to natural daylength extended to 20 h with cool‐white fluorescent light indicated that it should be E3E3. Mukden was crossed to E3E3 and e3e3 testers and progeny tested under the extended daylength conditions. Results confirmed that Mukden is E3E3. Data from the isoline‐tester field procedure were examined for E3 and e3 tester effects in comparison with those of E2 and e2. It appears that if there is not a greater mean effect, a larger range, and a greater phenotypic variance present for the alleles of a tester gene, then additional information is needed before maturity genotypes at that locus can be assigned with confidence to tested cultivars.
Frequency of 1RS.1AL and 1RS.1BL Translocations in United States Wheats
Authors: Lukaszewski Adam J.
Published: July 2010

Translocations of the short arm of rye (Secale cereale L.) chromosome IR in wheat (Triticum aestivum L. em Thell.) offer several resistance genes, and possibly increase yield, but adversely affect bread‐making quality. The objective of this study was to determine the frequency of such translocations in wheats bred in the USA. Two hundred and seven entries in six major 1989 wheat nurseries and 30 entries in the 21st International Winter Wheat Performance Nursery were cytologically screened using C‐banding. Among USA wheats, 4.3% had the IRS.1AL translocation and 7.1% had the 1RS.1BL translocation. In the international nursery, 38.1% of lines had the IRS.IBL translocation and one line, ‘TAM 200’ from Texas, had the 1RS.1AL translocation. In addition, several translocations between wheat chromosomes were detected. This information may aid wheat breeders in selection of crossing partners in crossing blocks.
Diallel Analysis of Maize Inbreds for Resistance to Gray Leaf Spot
Authors: Ulrich J. F. , Hawk J. A. , Carroll R. B.
Published: July 2010

Gray leaf spot (GLS) (caused Cercospora zea e‐maydis Tehon & Daniels) is becoming an increasingly prevalent disease of maize (Zea mays L.) in the USA. This study was conducted to determine the inheritance of GLS resistance. Nine inbreds and their 36 singlecross hybrids were evaluated for resistance in field studies conducted in 1987 and 1988. Plants were rated for disease development on a plot basis using a scale of 0.5 (resistant) to 5.0 (susceptible). weighted entry means for each year were analyzed using Gardner and Eberhart's diallel Analysis III for fixed effects. Highly significant (P < 0.01) genotypic and general combining ability (GCA) differences were seen for resistance; the specific combining ability (SCA) mean square was not significant. Inbreds T222 and Mo18W had significant negative (P < 0.01) GCA effects of −0.81 and − 0.76, respectively, and were significantly more resistant in crosses than the other inbreds. The mean rating of crosses involving CI64 (GCA = ‐−0.28, P < 0.05) was lower than the mean of crosses involving the three susceptible inbreds Mol7Ht, DE811, and B73Ht (which had positive GCA effects of 0.26 [P < 0.05], 0.47, and 1.08 [P < 0.01], respectively). As an inbred and in crosses, B73Ht was more susceptible than any other inbred evaluated, rating 3.1 in crosses compared with 1.6 for both T222 and MoI8W. The high level of resistance in inbreds T222 and Mo18W may be bred into elite, but GLS‐susceptible, lines using backcross or recurrent selection procedures that utilize additive effects.