bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fallow and Sesbania Effects on Response of Transplanted Lowland Rice to Urea
Authors: Buresh R. J. , Garrity D. P. , Castillo E. G. , Chua T. T. 
Published: July 2010

AbstractAlthough lowland soils in Asia are frequently fallowed between rice (Oryza sativa L.) crops, little is known about the effects of fallow management on N cycling and growth of a subsequent lowland rice crop. A 2‐yr field study was conducted in the Philippines on a Typic Tropaquept to determine the interactive effects of pre‐rice land management and urea fertilization on rice growth, N uptake, and response to applied N. Management treatments before transplanting wet‐season rice were (i) weedy fallow (WF), (ii) weed‐free fallow (WFF), and (iii) Sesbania rostrata Bremek. & Oberm. grown in situ for either 45 or 60 d as green manure (SR). Weeds and S. rostrata were incorporated after soil flooding on 23 June of each year, and rice was transplanted on 30 June 1989 and 4 July 1990. Four rates of urea‐N (0, 40, 80, and 120 kg N ha‐1) were applied to rice following each pre‐rice treatment. The efficiency of added N with respect to dry matter accumulation (kg dry wt. kg−1 N applied) was reduced following WF and SR compared with that following WFF at 45 d after transplanting (DAT), about 10 to 15 d after panicle initiation. Rice recovered from the initial adverse effect of incorporated plant residue, and growth rate after 45 DAT was greater following SR and WF than that following WFF. Grain yield without applied urea was 0.9 Mg ha‐1 higher following WF than that following WFF. Incorporated weed‐N (35 kg N ha‐1) substituted for 40 kg urea‐N ha‐1. High initial rice growth rate in the absence of incorporated plant residue (WFF) resulted in a lower rice N concentration at 45 DAT. Incorporated S. rostrata and weeds continued to provide N to rice after 45 DAT. When no plant residues were incorporated (WFF), the application of only one‐third of the total urea‐N at panicle initiation was insufficient to meet the N requirements of rice. Basal urea‐N (two‐thirds of the total urea‐N) failed to increase rice dry weight or N concentration at 21 DAT following all pre‐rice treatments. Results suggest that optimal distribution of urea among application timings might depend on whether plant residues are incorporated before transplanting.
Long‐Term Tillage and Crop Rotation Effects on Winter Wheat Production in Northern Idaho
Authors: Hammel John E. 
Published: July 2010

AbstractReduced tillage practices designed to control soil loss in the Palouse region of northern Idaho may adversely affect soil physical properties and decrease yields. The objective of this study was to determine the effects of long‐term tillage and rotation practices on wheat (Triticum aestivum L.) yields following 10 yr of continuous management. Yields were obtained from 1984 to 1987 on a long‐term tillage rotation experiment established in 1974 near Moscow, ID. Tillage treatments included conventional (CONV, moldboard plow), minimum (MIN, chisel), and no‐tillage (NT). Crop rotations were a 2‐yr winter wheat‐spring pea (Pisum sativum L.) (WW‐SP) rotation and a 3‐yr winter wheat‐spring barley (Hordeum vulgare L.)‐spring pea (WW‐SB‐SP) rotation. Yields of the MIN and NT treatments averaged over the 4‐yr period were 92 and 78% of the CONV treatment. Differences between yields were significant (P <0.05). No‐till yields were significantly less (P < 0.05) than both the CONV and MIN treatments during all years, whereas MIN and CONV yields were not significantly different during 1986 and 1987. Wheat grown under the WW‐SB‐SP rotation yielded significantly greater (P < 0.05) than the WW‐SP rotation. Profile water extraction and N uptake were reduced in the MIN and NT treatments. The apparent decrease in root function may have resulted from higher surface layer impedance, or possibly, greater root disease pressure under MIN and NT management. Results indicate that winter wheat production under continuous no‐till management in the Palouse region may not be feasible without substantial yield reductions. A reduced tillage system that utilizes some limited tillage appears to be a viable management alternative to conventional practices.
An Automated Plot Harvest System for Use with a Commercial Forage Harvester
Authors: Pedersen Jeffrey F. , Moore Kenneth J. 
Published: July 2010

AbstractThis automated harvest system is based on minimal modification of currently available commercial forage harvesters. Using 6.8 m plots separated by 0.75 m alleys, a single operator can harvest, finely chop, and collect wet plot weights of forage sorghum [Sorghum bicolor (L.) Moench] or pearl millet [Pennisetum glaucum (L.) R. Br.] in <1 min per plot. Harvested material is deposited in a pile in the center of each plot. Subsamples for moisture and quality analysis can easily and safely be obmined from the pile.
Effect of Shade on Maize Production Under Field Conditions1
Authors: Earley E. B. , Miller R. J. , Reichert G. L. , Hageman R. H. , Seif R. D. 
Published: July 2010

Studies were made in 1954, 1955, and 1956 of the effects of various quantities of normal sunlight, obtained by the use of shade structures, on growth and grain production of three corn hybrids: Illinois 972A, Hy2 ✕ Oh41 (tolerant of high rates of planting), and WF9 ✕ C103 (intolerant of high rates of planting). The light treatlnents in 1954 were 100% (control), 70, 40, and 10%; 1955 and 1956, additional treatments of 30 and 20% were used. Shading was initiated in 1954, 1955, and 1956 on July 2, July 5, and June 8 thus providing 90, 72, and 113 days of treatment, respectively.In general, there was a significant decrease in measured components (grain, stover, total protein, total oil, etc.) as light was decreased. With minor exceptions, e.g., height, reduction of light by even 30% caused a decrease in production of plant material. Of signal importance is the essentially linear reduction in total plant (grain and stover) protein with decrease in light.Based on grain yields, Hy2 ✕ Oh41 proved to be more tolerant of low light levels than did WF9 ✕ C103 when shade treatments were imposed in mid‐season at a time when mutual shading becomes intense in dense plant populations.
Effects of Honey Bee Activity and Cages on Attributes of Thin‐Hull and Normal Safflower Lines1
Authors: Rubis D. D. , Levin M. D. , McGregor S. E. 
Published: July 2010

Two safflower lines, a thin‐hull and normal, were subjected to three treatments; caged without bees, caged with bees, and not caged with bees, at Tucson, Arizona. Cage and bee effects were determined on eight attributes and the daily foraging activity of honey bees on the two lines were observed.Cage treatments decreased yield, bushel weight, and hull percentage and increased oil percentage of the normal line. On the thin‐hull line cage effects were of a smaller magnitude but decreased yield, number of seeds per head and percentage of deformed seedlings and increased germination percentage. Effects of bee pollination on the normal line were non‐significant except for a slight decrease in hull percentage. Bee pollination in the thin‐hull line doubled yield, quadrupled the number of seeds per head, reduced weight per 100 seeds, and increased oil percentage.Honey bee activity differed on the two lines. Pollen collectors worked only the normal line whereas nectar collectors worked both lines equally.
Elymus caput‐medusae L. Crosses with Aegilops cylinderia Host1
Authors: Schooler A. B. 
Published: July 2010

A fertile allohexaploid was obtained from a cross between E. caput‐medusae (2n=14) and Ae. cylindrica (2n=28). The F1 intergeneric hybrid was larger than either parent in most morphological characteristics, but lacked the 3‐ or 4‐inch awns of E. caput‐medusae. The F1 and amphiploid more closely resembled the Aegilops parent than Elymus. The embryo culture technique was used in obtaining the F1 hybrid.The F1 hybrid had a chromosome complement of 2n=21 and was sterile. Chromosome behavior was irregular and variable in the microsporocytes examined of the F1 hybrids. Chromosome doubling was induced in the F1 hybrid by colchicine treatment producing the fertile amphiploid intergeneric hybrid (2n=42).
Effect of Mass Selection and Thermal Neutron Irradiation on Genetic Variances in a Variety of Corn (Zea mays L.)1
Authors: Lonnquist J. H. , Cota O. , Gardner C. O. 
Published: July 2010

Two samples of ‘Hays Golden’ variety of corn have undergone 6 generations of mass selection for yield. One sample had been subjected to thermal neutron irradiation of the seed at generation 0 and generation 2. Sixty‐four half‐sib families each consisting of 4 full‐sib families were produced in the original variety and in each of the 2 mass selected populations to study the changes in genetic variability which may have resulted from the selection practiced.The 6 generations of mass selection for yield resulted in signficant increases in productivity in each of the 2 populations with no decline in additive genetic variability. The population derived from seed treated with thermal neutron irradiation and mass selected for yield of grain exhibited appreciably higher additive genetic variance than the original variety. Indications point to continued expected gains from selection of the type practiced.
Interaction of Plant Spacing and Combining Ability in an Eight‐Clone Diallel of Medicago sativa L.1
Authors: Evans Kenneth H. , Davis R. L. , Nyquist W. E. 
Published: July 2010

The diallel progenies of 8 alfalfa clones were grown in rows 1 and 3 feet apart and spaced 2, 8, and 24 inches within rows. Yield, plant width, plant height, crown width, and vigor were measured in each of 2 years; leafhopper yellowing and leafstem ratio were measured in 1 year. The general combining ability, specific combining ability, maternal, reciprocal, and their interaction effects with spacings and years were studied.General and specific combining abilities were significant for all characters measured. Maternal effects for some characters were significant, while reciprocal effects were generally nonsignificant. General combining ability effects and specific combining ability effects were consistent across spacing‐year treatments. Maternal effects were less consistent across treatments, yet were positively correlated between treatments. Since the number of plants per linear foot of row in the 2‐inch spacing within rows 1 foot apart was very close to the number of plants in a 2‐year‐old broadcast seeding, the data suggested that progenies could be evaluated in spaced plantings with small quantities of seed.
Leucaena Cytogenetics in Relation to the Breeding of Low Mimosine Lines1
Authors: Gonzalez Ventura , Brewbaker James L. , Hamill D. Elizabeth 
Published: July 2010

Cytological and biochemical studies were conducted in the genus Leucaena in relation to the breeding of low mimosine, high yielding forage types of L. leucocephala (Lam.) de Wit. Meiotic and mitotic chromosomes were studied in the following species; L. leucocephala and L. pulverulenta (Schlecht) Benth. (2n = 56); L. trichodes Benth., L. lanceolata (S. Wats.), L. stenocarpa (Urban), and accessions designated “L. buitenzorg” (2n = 52) and “L. esculenta” (2n = 104).All species of Leucaena hybridized freely, insofar as they were tested. The 80‐chromosome hybrids of L. pulverulenta ✕ L. leucocephala were grown and studied in detail. Seed recovery and yields of these hybrids were high, despite meiotic chromosome pairing of 26 bivalents and 28 univalents. F2 plants ranged widely in chromosome numbers.Assays for the toxic alkaloid, mimosine, were conducted on F1, F2, and backcross progenies from a cross of high ✕ low mimosine strains of L. leucocephala. Despite the apparent polyploidy of the species, wide variations were observed in mimosine contents of the segregating generations, enabling the selection of plants with less than 30% of the normal mimosine values (ca. 4% dry weight) of tropical forage strains. The correlation between mimosine and protein contents for related F2 segregants from high ✕ low mimosine crosses was not significant (r = .60).
Sampling Red Clover for Nectar Yield Components and Corolla‐Tube Length1
Authors: Dade Eugene 
Published: July 2010

Red clover heads were selected from a stand of ‘Lakeland’ red clover when corolla coloration was apparent and before appreciable expansion of florets had occurred. The selected heads were covered with gauze bags to exclude nectar‐collecting insects. Heads were collected on a schedule 3 to 9 days later.Average weight of head, number of functional florets, nectar volume, and nectar volume per floret increased to the 6th day after selection. Afterwards, there were no significant changes in the means of these characteristics. Percent sugar increased slightly with advancing age of head. Corolla‐tube length increased to the 6th day. Corolla tubes borne on the mid‐verticil were longer than those borne on the lower and upper verticils.During the season, average weight per head and number of functional florets decreased significantly. Corollatubes selected from the lower and mid‐verticils were significantly shorter at the end of the season. Correlations between cumulative solar radiation and the measured characteristics and correlations among the characteristics were of limited value in explaining differences hi nectar yield during the season.The importance of specific selection criteria and collection 6 to 7 days after selection is emphasized in sampling for red clover nectar yield and corolla‐tube length.
Selection Among and Within Half‐Sib Families in a Brazilian Population of Maize (Zea mays L.)1
Authors: Paterniani E. 
Published: July 2010

A modified ear‐to‐row selection (selection among and within half‐sib families) has been applied to a Brazilian population of maize. Open‐pollinated progenies (half‐sibs) are evaluated in replicated yield trials. The selected half‐sib families are further subjected to mass selection within families to provide the half‐sibs for testing in the next generation. Three cycles of selection have been completed. Selection was mainly for yield. Some attention was given to such agronomic characters as resistance to lodging, lower ear height, and freedom of diseases.Yield improvement of 13.6% per cycle compared to the original population was obtained. The original population variability as measured by a genetic coefficient of variability was 15.8%; in cycle III, this value decreased to 7.1%. Most of the decrease occurred in the first cycle and comparable improvements in succeeding cycles were obtained without further apparent loss of genetic variability.The present scheme of improvement appears to be of value in comparison with other methods of population improvement.
Effectiveness of Index Selection Relative to Selection on Yield Alone at Several Levels of Soil Phosphorus1
Authors: Johnson G. R. 
Published: July 2010

Expected genetic advances for oat grain yields were calculated at four levels of soil phosphorus using selection indices composed of various combinations of the following attributes: plant height, plant weight, panicle number, average spikelet number per panicle, weight per 100 seeds, and yield itself. The genetic materials used were 24 oat cultivars grown as subplots in a splitplot design in which the phosphorus levels were whole. plot treatments. The phosphorus was applied at rates of 0, 22.5, 45, and 90 kg/ha of actual P, and the subplots were hills spaced 30.5 cm within and between rows. Genetic and phenotypic variances and covariances used to calculate the selection indices were obtained from variance and covariance component estimates derived from randomized‐block analyses performed on each phosphorus level.Among the indices calculated, only the index composed of panicle number plus yield had any appreciable advantage compared with selection on yield alone. The relative value of the index diminished at higher phosphorus levels because, as phosphorus was increased, heritability of the index increased less rapidly than heritability of yield itself. The results suggested that selection for yield would be more efficient at high levels of plant productivity, but that panicle number might be an effective aid to yield selection at low productivity levels.
Inheritance of Drying Rate in “Mature” Corn (Zea mays L.)1
Authors: Purdy J. L. , Crane P. L. 
Published: July 2010

Three “fast” drying and three “slow” drying corn inbreds, whose hybrids demonstrate various rates of drying after physiological maturity, were used to study the genetics controlling differential drying rates among hybrids. Drying rate was estimated by the moisture loss from husked ears in a forced‐air dryer at 38 C for 18 hours. Initial moisture range was 30 to 40% while dried ears had a range of 20 to 30%.Correlations in this population indicate that selection for faster drying rate would most likely result in smaller ears, later silking date, and lower moisture content at 60 days after silking. Phenotypic and genotypic correlations were moderately high and similar. Most environmental correlations were nonsignificant.Diallel analysis indicated significant differences for both general and specific combining ability effects with the additive component more important than the non‐additive; therefore, drying rate is fixable.Broad sense heritability estimates obtained by the F2 variance method were moderately high, while higher estimates were obtained by genetic components of variance from F1 replication means. High heritability was also indicated by the genetic correlations. Estimates of HMb were between 52% and 95%.Xenia effect on differential drying rates was generally found to be non‐significant.Determination of drying rate by use of forced‐air dryers offers a good approach for the plant breeder in selection for faster drying rates.
Meiosis and Pollen Stainability in Switchgrass, Panicum virgatum L1
Authors: Barnett F. L. , Carver R. F. 
Published: July 2010

Chromosome number, meiotic behavior, and pollen stainability were studied in switchgrass plants originating mainly in Kansas and Oklahoma. Tall, coarse, glabrous plants, referred to as “lowland”, were tetraploid (2n =36). Shorter, finer plants, featuring varying amounts of leaf blade pubescence and referred to as “upland,” were mostly octoploid. One upland plant was hexaploid, however, and four were aneuploid near the 72‐chromosome level.Tetraploids were more regular meiotically and exhibited a higher frequency of well‐stained pollen than either octoploids or aneuploids. Octoploids and aneuploids were similar in meiotic behavior, but the former exhibited a higher frequency of well‐stained pollen.Genetic distinctness of upland and lowland populations was suggested. Asexual reproduction seemed unlikely in tetraploids. It appeared more likely at higher levels of polyploidy where extreme meiotic irregularity suggested materially reduced sexual fertility in occasional plants.
Relative Efficiency of Experimental Designs With Systematic Control Plots for Alfalfa Yield Tests1
Authors: Melton Bill , Finkner M. D. 
Published: July 2010

The relative efficiencies were determined for the randomized complete blocks and two lattice designs with systematically arranged control plots. All experimental data were analyzed with and without covariance, first as randomized blocks and then as lattices. The average of the two control plots lying adjacent to each entry was used as the concomitant variable in the covariance analysis.The use of systematic controls in a covariance analysis resulted in increased efficiencies from 38 to 528%. The effectiveness of the covariance models increased with the age of the stand. Coefficients of variability and F‐values were also compared. Other advantages in the use of systematic controls were the small size of experimental area required, small amount of seed per entry and the value of control plots in making subjective evaluations of entries.
Reciprocal Recurrent Selection and Modifications in Simulated Populations1
Authors: Cress C. E. 
Published: July 2010

Computer simulation was conducted by the Monte Carlo method for a bisexual organism with two allels at each of 40 independently segregating loci. Reciprocal recurrent selection and two modifications were performed for the completely dominant and purely overdominant models at a number of starting gene frequencies. Genetic divergence is an unsound basis for selecting starting populations when the goals of selection are long term. A short term increase in the means of the recurrent populations cannot be used as evidence for a predominance of partially or completely cominant gene effects.Two modifications are important for the improvement of genetic potential and rate of progress for types of recurrent selection using progeny testing. 1) A synthetic variety should be made from all material entered into a moderate to long term recurrent selection program. 2) One generation of selling (or other inbreeding) should precede the test crosses in each cycle, where the progress per unit time indicates this is more efficient.
Effect of Clipping and Nitrogen Fertilization on Yield and Stands of Tall Fescue1
Authors: McKee W. H. , Brown R. H. , Blaser R. E. 
Published: July 2010

Two experiments were conducted in the field during spring and summer to study effects of nitrogen level, time of fertilization, and defoliation, and their relationships on yield and tillering and on carbohydrate and nitrogen content of the stubble.Stand reduction by N and defoliation in ‘Kentucky 31’ fescue appears to be related to morphological stage of growth and season. Stands were reduced at high N levels in spring when grass was cut at flowering stage but not if cut frequently. Stands and regrowth during summer were reduced only slightly by high N. Soluble carbohydrates in stem bases were reduced with high N fertilization and N content was increased. Differences in chemical constituents due to treatments disappeared 20 to 30 days after regrowth.Faster regrowth was obtained when N was applied 5 days before clipping or at time of clipping as compared with 7 days later. Fast regrowths were associated with decreases in organic reserves.
An Evaluation of Modified Ear‐to‐Row Selection in a Population of Corn (Zea mays L.)1
Authors: Webel O. D. , Lonnquist J. H. 
Published: July 2010

Four cycles of modified ear‐to‐row selection have been applied to the open‐pollinated variety, ‘Hays Golden.’ The objective of this research was to evaluate the effectiveness of combined selection for yield of grain. The method entails selection among and within half‐sib families. The family selection was based on the average performance in three replications, one at each of three locations. The selection of individuals within selected families was based upon phenotypic performance in a natural crossing block isolation.The mean yield increased an average of 9.44% per cycle relative to the parental variety. The predicted gain from selection based upon estimates of genetic and geneticenviromnental variances in the original Hays Golden variety was in good agreement with the observed response for grain yield. A comparison with results published earlier using mass selection in the same variety indicates that the modified ear‐to‐row procedure is more effective than mass selection alone in improving yield in the Hays Golden varietal population.Modified ear‐to‐row selection may be used to obtain a more rapid increase in the frequency of favorable genes prior to the extraction of inbred lines. The method can be used to advantage after some reduction in the additive genetic variance has resulted as a consequence of effective mass selection and a more precise measure of the genotypic effect is needed.