bluuebunny/crossref_metadata_2025 huggingface dataset:
Crop Production During Conversion from Conventional to Low‐Input Methods
Authors: Liebhardt W. C. , Andrews R. W. , Culik M. N. , Harwood R. R. , Janke R. R. , Radke J. K. , Rieger‐Schwartz S. L.
Published: July 2010

A 5‐yr cropping system experiment was initiated in 1981 to study transition from a conventional agricultural system using pesticides and fertilizers to a low‐input system. The site was primarily Comly silt loam (fine‐loamy, mixed, mesic, Typic Fragiudalf) with 12% Berks shaly silt loam (loamy‐skeletal, mixed, mesic, Typic Dystrochrept), and a small area of Duffield silt loam (fine‐loamy, mixed, mesic, Ultic Hapludalf), in Berks County, eastern Pennsylvania. Three 5‐yr rotations were compared. A conventional corn (Zea mays L.)‐soybean [Glycine max (L.) Merr.] rotation (designated “conventional”) was compared to two low‐input rotations which utilized oat (Avena sativa L.), red clover (Trifolium pratense L.) and winter wheat (Triticum aestivum L.), in addition to corn and soybean. One low‐input rotation used cattle manure as a nutrient source and produced forage crops in addition to cash crops (designated “low‐input/livestock”), while the other used legume crops as a nutrient source, and produced a cash crop every year (designated “low‐input/cash grain”). Corn grain yields in the low‐input systems were 75% of conventional in 1981 to 1984, but yields were not significantly different in 1985. Weed competition and insufficient N limited low‐input corn yields during the first 4 yr. Soybean yields in the low‐input systems were equal to or greater than conventional all 5 yr. It is concluded that a favorable transition from input‐intensive cropping to low‐input systems is feasible, but only if crop rotations are used which include crops that demand less N and are competitive with weeds, such as small grain, soybean, or legume hay. Corn should be avoided for the first 3 to 4 yr.
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

Although 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

Reduced 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

This 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.
Botanical Composition, Light Interception, and Carbohydrate Reserve Status of Grazed ‘Florakirk’ Bermudagrass
Authors: Pedreira Carlos G.S. , Sollenberger Lynn E. , Mislevy Paul
Published: July 2010

‘Florakirk’ bermudagrass [Cynodon dactylon (L.) Pers.] is a new cultivar that has persisted well under grazing in the warmest parts of the southeastern USA. Data are lacking on persistence‐related responses from areas of the South where frosts and freezes occur more frequently. In 1993 and 1994, the effect of grazing management on pasture botanical composition, light interception, and reserve status was studied on a sandy, siliceous, hyperthermic Ultic Haplaquod. Treatments were replicated twice in a randomized block design and consisted of all combinations of three lengths of rest period (7, 21, and 35 d) and three postgraze stubble heights (8, 16, and 24 cm). Percentage of Florakirk in herbage mass was 96 or greater and was not affected by grazing treatment. Postgraze light interception was affected only by stubble height; it was as low as 22% for stubble height of 8 cm and 78% or greater when stubble height was 24 cm. Close, frequent grazing had no apparent detrimental effect on Florakirk persistence after 2 yr. The total nonstructural carbohydrate (TNC) pool in rhizomes plus stem bases declined with increasing stubble height in both years (96 to 68 g m−2 in 1993, and 44 to 27 g m−2 in 1994). Lower rhizome TNC pools in 1994 than in 1993 were not associated with reduced herbage accumulation or vigor. Results from 2 yr of grazing suggest that Florakirk persists under a range of rotational stocking treatments, so grazing management decisions can be based primarily on productivity and nutritive value considerations.
Leaf‐Cutter Psychrometers: A Cautionary Note
Authors: Turner Neil C. , Shackel Kenneth A. , Le Coultre Ian F.
Published: July 2010

Nontranspiring (covered) leaf water potential on greenhouse‐grown chickpea (Cicer arietinum L.) leaves was measured with the pressure chamber and leaf‐cutter psychrometer techniques over a range of water potentials. Potentials measured with the leaf‐cutter psychrometer technique were highly variable and not well correlated with the values measured with the pressure chamber. The objectives of this study were to identify the basis for the discrepancy between the two techniques and to identify procedures to minimize the errors. Intentionally damaging 15% of the disc caused an increase (less negative) in the potentials measured in the psychrometers relative to those measured in the pressure chamber. When leaves were sampled with a sharp razor or a new biopsy punch, however, potential values similar to those measured by the pressure chamber were obtained. We conclude that unintentional damage caused by the psychrometer's cutter can give erroneous values of leaf water potential measured by leaf‐cutter psychrometry.
Optimizing Nitrogen Application Timing in No‐Till Soft Red Winter Wheat
Authors: Weisz Randall , Crozier Carl R. , Heiniger Ronnie W.
Published: July 2010

As no‐till acreage increases, N management guidelines need re‐examination due to the potential effects of surface residue on N transformations and crop development. Our objectives were to determine: (i) if N applied at Zadok's Growth Stage (GS) 25 improves grain yield of no‐till winter wheat (Triticum aestivum L.), (ii) if any yield increase was the result of increased spring tillering, and (iii) if there is a critical tiller density above which N application at GS‐25 in no‐till wheat was not required. Research was conducted at three sites in North Carolina with seven site‐years between fall 1996 and spring 1999. A continuum of GS‐25 tiller densities was generated (161‐1774 tillers m−2) by planting at different seeding rates and dates in a randomized complete block design. Five N treatments were applied at GS‐25, and three were applied at GS‐30. Tillering response to early spring N, yield, and yield components were measured. increasing early spring N rates resulted in higher tiller densities at GS‐30, and GS‐25 tiller density was a significant covariate. With GS‐25 tiller densities >550 tillers m−2, yields were higher when all N was applied at GS‐30. In years without spring freezes, wheat with <550 tillers m−2 achieved optimum yields when spring N was applied at GS‐25. Manipulating the timing of spring N application can optimize early spring tillering and yield component formation.
Studies in Male‐Sterile Barley. II. Pollen Abortion1
Authors: Kaul C. L. , Singh S. P.
Published: July 2010

We compared microsporogenesis and pollen development on four male sterile lines of barley and their fertile counterparts. Two lines were six‐row and two were two‐row types. Development through meiosis was similar in fertile and sterile lines but subsequently the microspores in the fertile lines formed mature pollen grains, whereas those in sterile lines degenerated. In six‐row types, degeneration occured at the free microspore stage, but in two‐row types it took place even while the microspores were still enclosed by the wall of the microspore mother cell.
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.
Culm Length and Differential Development of Three Foliar Leaves of Near‐Isogenic Wheat Lines1
Authors: Chowdhry A. Rehman , Allan Robert E.
Published: July 2010

Five near‐isogenic lines of wheat seedlings that differed in culm length and their two parents were studied to establish the relationship of culm length phenotype and genotype with differential development of the first, second, and third seedling leaves. Differential development of the corresponding leaves of these selections is generally positively related to culm length expression. Indirect evidence suggests that the genetic mechanisms which control culm length also control leaf development or that closely linked systems are inwflved. Furthermore, differential leaf development is brought about by differential elongation of leaf mesophyll parenchyma cells. Differential development of the leaves of the same selection seems more dependent upon differential parenchyma cell number rather than length of leaf parenchyma cells. On a per‐unit‐length basis, leaves of the short selections possessing semidwarfing genes are heavier than those carrying no semidwarfing genes, suggesting some physiological limitation for semidwarf selections to produce maximum cell elongation.
Interspecific Hybridization with Paspalum spp.1
Authors: Bennett Hugh W. , Bashaw E. C.
Published: July 2010

The morphology and cytology of 11 interspecific Paspalum F1 hybrids are described. Species used were: dilatatum (common, sexual, and Var. pauciciliatum), pubiflorum, platyphyllum, urvillei, virgatum, and malacophyllum. The percent crossability and chromosome pairing relationships indiate that the species are not closely related. Hybrids obtained using P. dilatatum as the female parent appear to be developed from fertilization of an unreduced egg and all are apomictic. When P. dilatatum was used as the male parent, the mode of reproduction of the hybrids varied with the female parent. The prevalence of apomixis in the genus and the occurrence of the stable apomict, P. dilatatum, suggest that apomixis might have been an important factor in Paspalum speciation. The economic importance of the hybrids reported has not yet been shown, but the fact that apomixis was broken through interspecific hybridization is significant. Interspecific hybridization and the possible manipulation of apomixis offers a valuable approach to the improvement of plants in the Paspalum genus.
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).
Nucleolus‐Organizing Accessory Chromosomes in Pearl Millet, Pennisetum typhoides1
Authors: Powell Jerrel B. , Burton Glenn W.
Published: July 2010

Accessory chromosomes were discovered in an inbred line of pearl millet, Pennisetum typhoides (Burm.) Stapf and C.E. Hubb. The accessory chromosomes organized nucleoli which were independent of the A‐chromosome nucleolus in some microsporocytes and associated with the A‐chromosome nucleolus in others. Two A‐chromosomes in this inbred line associated with a single nucleolus in contrast to only one nucleolus‐organizing A‐chromosome commonly found in most pearl‐millet lines. Accessory chromosomes ranged from one to five within plants, and varied in number from plant to plant, head to head, spikelet to spikelet, and cell to cell. Small, intermediate, and large accessories were obesrved. Characteristic folding back on itself at diakinesis exhibited by the larger accessory suggested an isochromosome derived from the intermediate‐sized accessory. The number of accessories per cell appeared to have little effect on A‐chromosome pairing. Microsporocytes with the least amount of accessory‐chromosome association also had the least A‐chromosome pairing.
Relationships Among Stem‐Rust Genes on Wheat Chromosomes 2B, 4B, and 6B
Authors: Loegering W. Q. , Sears E. R.
Published: July 2010

Pathological and genetic studies involving ‘Chinese Spring’ substitution lines showed that the varieties ‘Kenya Farmer’ and ‘Sapporo No. I’ both carry the Sr7a gene for resistance to Puccinia graminis tritici on chromosome 4B (VIII). ‘Hope’ carries a different allele, Sr7b. The presence of the resistance gene Srll on chromosome 6B (X) of both ‘Timstein’ and Kenya Farmer was confirmed, as was the existence of two alleles for resistance at the Sr9 locus on chromosome 2B (XIII) of ‘Red Egyptian’ (Sr9a), Kenya Farmer (Sr9b), and ‘Kenya 117A’ (Sr9b). ‘Thatcher’ chromosome 2B carries an independently inherited gene designated Srl6. The existence of alleles for resistance to stem rust confers an advantage on hybrid wheat, which can have two different resistance genes at a single locus.
Natural Selection for Cold Resistance in Winter Oat Bulk Populations1
Authors: Marshall H. G
Published: July 2010

The effect of 3 consecutive years of severe natural selection pressure on the cold resistance of 23 different winter oat bulk populations during the F3, F4, and F5 generations was determined. Controlled freezing tests with remnant seed from these generations and the F2, which was not subjected to winter stress, demonstrated that natural selection caused a significant increase in cold resistance each year when averaged over all populations. The total change in cold resistance during the three generations was significant for 17 of the 23 populations, and the amount of change was negatively correlated with the initial level of cold resistance. Although the amounts of winterkilling in individual plots were not consistent with the changes in cold resistance, the totals over the 3 years for these characteristics were positively correlated. The correlation coefficients between survivals of the various generations were all significant. It was concluded that natural selection increased cold resistance when the initial survival value of a population was low in response to the selection pressure for winter survival. Although F3 cold resistance provided a relatively accurate prediction of F6 performance, the low populations had the greatest potential for change under the selection pressures which prevailed.
Morphological and Cytological Response of Pear Millet, Pennisetum typhoides to Thermal Neutron and Ethyl Methane Sulfonate Seed Treatments1
Authors: Burton Glenn W. , Powell Jerrel
Published: July 2010

Three dosages each of thermal neutrons (TN) and ethyl methane sulfonate (EMS) were applied to 10 pearlmillet inbreds evaluated in replicated plots in the field. Both mutagens delayed seedling emergence and days to maturity, and reduced seedling height, plant height, leaves per culm, and selfed and sibbed seed set. EMS reduced percent emergence and plants per plot to reach maturity. This extra space allowed EMS‐treated survivors to produce more culms and yield more. Two‐thirds of the 56 sectorial mutants came from TN‐treated seed. Significant inbred ✕ treatment interactions were obtained for 5 of 13 characters studied. Frequencies of chlorophyll‐deficient seedlings from selfed seed of all plants indicated that the 90‐minute TN treatment and 0.4% EMS soak for 4 hours increased the average mutation frequency most (some 5 fold). Mutation frequency in inbreds varied greatly. The most effective EMS treatment induced over 8 times as many mutants in 1 inbred as in another. The 90‐minute TN treatment produced 4 times as many plants (28%) with chromosome interchanges as the heaviest EMS treatment.
Mutagenic and Chromosomal Effects of X‐rays and Alkylating Chemicals on Triticum durum Desf. ‘Lakota’1
Authors: Edwards L. H. , Williams N. D.
Published: July 2010

Seeds of Lakota durum were treated with X‐rays, ethylene imine (EI), diethyl sulfate (DS), and ethyl methanesulfonate (EMS). Each chemical mutagen produced chromosomal aberrations in less than 3.0% of the M1 spikes examined; whereas, X‐rays produced aber rations in 7.6 to 77.2% of the M1 spikes as X‐ray dose increased from 7.5 to 30.0 kr. Treatments with 0.5% EMS and 0.02% DS induced chlorophyll‐deficient mutations in 23.33 and 6.94% of the M1 spikes, respectively. The highest mutation rates induced by EI and X‐rays were 2.64 and 3.82% mutated M1 spikes, respectively.
Inheritance of Capsule Drop Resistance and Pedicel Length in Castorbeans, Ricinus communis L.1
Authors: Culp Thomas W.
Published: July 2010

Inheritance and linkage relationship of capsule drop resistance and pedicel length in castorbeans, Ricinus communis L., were investigated. Segregating generations from crosses indicated that the variety Baker 296 and the ornamental line MW‐1 must possess at least one and two genes for capsule drop resistance, respectively. One of the loci for capsule drop resistance in MW‐1 was closely linked with an estimated 10% recombination with the locus or loci for short pedicels. Complex interactions of disease organisms, plant characteristics and environment caused inaccuracies in classification and difficulties in interpretation of the data.
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.
Malting Quality in F1 Hybrids of Barley1
Authors: Rasmusson D. C. , Upadhyaya B. R. , Glass R. L.
Published: July 2010

Seed of 8 varieties of barley and all possible F1 hybrids from crosses among the varieties were malted to obtain data on 8 malting quality characters. On the average, significant heterosis as measured from the mid‐parents was observed in the F1 hybrids for percent extract, percent malt nitrogen, and percent plump kernels. The F1 hybrid average for percent extract was intermediate between the mid‐parent and high‐parent average. F1 hybrid averages for percent malt nitrogen and percent plump kernels were similar to the low‐parent and high‐parent averages, respectively. The average value for the 28 F1 hybrids and average mid‐parent value did not differ for percent wort nitrogen, ratio of wort to malt nitrogen, diastatic power, 6‐amylase, or β‐amylase. For these characters, with only two exceptions, the individual F1 hybrids did not differ significantly from the average of their parents. Only 7 of the 28 F1 hybrids were judged to be acceptable for all 8 malting quality characters. Six of these had an acceptable malting variety as one parent. Malting quality in the F1 hybrids appeared to depend largely on the frequency of favorable genes with additive effects, although for percent extract, percent plump kernels, and percent malt nitrogen there was evidence for genes having dominance and or epistatic effects.
Mechanism of Male Sterility in a Clone of Orchardgrass (Dactylis glomerata L.)1
Authors: Filion W. G. , Christie B. R.
Published: July 2010

Cytological and histological studies were carried out on a male‐sterile clone, OD‐1, of Dactylis glomerata L. The chromosome number and meiotic chromosome behavior of this clone were normal for the species. During microsporogenesis, degeneration of some sporogeneous tissue was observed at the initial stages of meiosis. Later, there was a very rapid degeneration of the tapetum and microspores. At anthesis, there was no evidence of pollen. The cell layers of the anther wall did not develop characterisfically, resulting in a small nondehiscent anther.
Possible Causes of Resistance to the European Corn Borer1
Authors: Scott Gene E. , Guthrie W. D. , Tipton Carl L.
Published: July 2010

The addition of both the “juice” and ether soluble “extract” from resistant to susceptible corn reduced larval survival to approximately half that found on plants treated with distilled water. These results indicate that at least a portion of the resistance of inbred CI31A, and of the single cross CI31A ✕ B49, is caused by a feeding deterrent of toxic substance present in these plants. The addition of juice or extract from susceptible plants to resistant plants had no effect on larval survival.
Heterosis and Homeostasis in Rye (Secale cereale L.) II. Production of Varieties, Intervarietal Crosses and Composite Populations under Various Population Densities1
Authors: Pfahler P. L.
Published: July 2010

Three diploid rye varieties, their 3 F1 populations, and 6 composite populations were compared for forage and grain production at 3 levels of population density in 2 years at Gainesville, Florida. Each composite population contained equal numbers of viable seeds from one F1 population mixed with one of its parents. Heterosis for forage and grain production was obtained in certain F1 populations, with indications that differences in combining ability between the varieties were present. The production of the composite populations could not be accurately predicted from the production of the F1 population and the parental variety involved. However, the presence of the parental variety in the composite populations did not appreciably lower and, in some cases, substantially increased production in comparison to the F1 population involved. In some instances, the presence of one of the parents in the composite population reduced environmental variability and altered the percentage contribution of various environmental components, thus making possible more flexibility in selection for specific environmental response patterns.
Preparation of Nucleic Acids and a Genetic Transformation Attempt in Maize1
Authors: Coe E. H. , Sarkar K. R.
Published: July 2010

Nucleoproteins and nucleic acids of apparently high quality can be prepared from maize seedlings by simple modifications of saline extraction and chloroform deproteinization procedures used to isolate transforming principles in bacteria. Seedlings are disintegrated by brief blending (2 minutes) with saline‐EDTA‐sodium lauryl sulfate; the mash is strained, brought to 1M with sodium perchlorate, and emulsified with chloroform; nucleoproteins are precipitated in crude form from the aqueous fraction with ethanol. Analyses indicate that protein content can be greatly reduced by additional deproteinizations, and that ribonucleic acid can be reduced relative to deoxyribonucleic acid by winding the highly fibrous precipitates. Crude precipitates dissolved in saline‐citrate, isolated from genetic material dominant for three plant characters and four seed characters, were injected into the apical meristem region of recessive recipient seedlings, repeating one to three times. Spermine, a stabilizing agent for deoxyribonucleic acid, was included in some of the treatments; part of the treated seedlings were irradiated with 1,000R of X rays immediately following injection. No phenotypic effects indicative of transformation in the treated plants were observed; five exceptional seeds (in 26,000 produced from intercrosses among treated plants) were derived from outcross contamination. Competence, nucleases, penetration, susceptibility of loci, numbers treated, and degradation are indicated as problems that may need to be considered and solved in order to achieve transformation in higher plants.
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.
Effects of Self‐Compatibility on Reciprocal Differences and Combining Ability in Medicago sativa L.1
Authors: Davis R. L. , Gartner Alvaro
Published: July 2010

Eight Medicago sativa L. clones ranging from 11 to 90% of the tripped florets forming pods were crossed by hand in all combinations with and without emasculation. The 28 F1 families and the 28 reciprocals made with and without emasculation were evaluated for seedling height, seedling weight, recovery, plant height, plant width, and plant weight. Significant reciprocal differences in both emasculated and unemasculated crosses were due to maternal effects (differences when clone was used as a female vs. when used as a male). The magnitude of the maternal effects was not influenced by the self‐compatibility of the clone. None of the mean squares for nonmaternal effects in reciprocal crosses were significant. The general combining ability effects were similar for both emasculated and unemasculated progenies irrespective of the self‐compatibility of the clone. The data suggested that the numbers of selfed plants produced when crosses were made in the greenhouse without emasculation were not related to the self‐compatibility of the clone.
Negative Evidence for Mutagenic Activity of the Maize Dwarf Mosaic Virus in Maize1
Authors: Dollinger E. J. , Findley W. R. , Williams L. E.
Published: July 2010

The frequency of dominant to recessive mutations for specific loci on three chromosomes in maize was the same in F1 endosperms from pollinations involving virus‐infected males and healthy controls. The data indicated that the maize dwarf mosaic virus was not mutagenic.
Genetics of the Smooth Stem Character in Gossypium hirsutum L.1
Authors: Lee Joshua A.
Published: July 2010

Normal Gossypium hirsutum displays an abundance of trichomes on the stems and leaves at all stages of vegetative development. A single plant of the strain Orinoco represents a radical departure from this pattern in that it has glabrous stems and pubescent leaves. Genetical studies revealed that glabrous stem is inherited as a simple dominant trait when Orinoco is crossed to the hirsute‐stemmed variety, Empire. The possible value of this new character as a marker stock is underscored.
Agents Affecting Survival of Red and White Clovers Exposed to Low Temperatures in a Freezing Chamber1
Authors: Kilpatrick R. A. , Judd R. W. , Dunn G. M. , Rich A. E.
Published: July 2010

A method was developed for testing tolerance of red and white clover plants to low temperatures. Plant survival was influenced by: the rate of temperature decrease during freezing; age of plants and low soil moisture at the time of freezing; and kind and extent of foliar disease prior to freezing.
Pollen Abortion in Male‐Sterile Hexaploid Wheat (#x2018;Norin’) Having Aegilops ovata L. Cytoplasm1
Authors: Chauhan S. V. S. , Singh S. P.
Published: July 2010

Another development and microsporogenesis were compared in male‐fertile wheat and a male‐sterile line, Nr 26. Premeiotic stages of anther development in both the strains are more or less normal, but in later stages, the sterile line shows abnormal development of three types. All three are present in every spikelet, but only one is observed in a single floret. In the central flower of the spikelet, the tapetal layer degenerates before the separation of sporogenous cells, followed by the degeneration of the latter. The degenerated mass is soon absorbed and the mature anther is left with only an epidermal layer. In one of the lateral flowers, the tapetum remains intact and is accompanied by the increase in nuclear size. Later, with the differentiation of exine and intine in microspores, the tapetal layer is completely absorbed. The pollen grains are devoid of germ pore, cytoplasm, and nuclei. The third type results in the formation of a tapetal periplasmodium when microspore mother cells enter meiosis. The contents of the plasmodium and microspore mother cell intermingle and start degenerating. The anthers are left with an epidermis, an endothecium and a degenerated mass of plasmodium and microspore mother cells. Male‐sterility in all the three types seems to result from improper nourishment of the developing sporogenous cells or the microspores due to abnormal behaviour of the tapetum.
Effect of Maturity on Amylose Content in the Sweet Corn Endosperm1
Authors: Kaukis Karl , Haunold Alfred
Published: July 2010

The amylose content in the sugary‐1 (su1) endosperm was related to the maturity of the kernels in four sweet corn single cross hybrids and their parents. A highly significant negative correlation existed between amylose and moisture content in the developing kernels. Amylose content was positively correlated with “heat unit” accumulation from silking to processing maturities and with alcohol insoluble solids (AIS) present in the endosperm. The amylose content in F1 hybrids generally was intermediate to the parental values but usually approached the low‐amylose parent. Taste variations among sweet corn hybrids could not be related to the endosperm amylose content at processing maturities. The morphological differences of starch granules in immature endosperms were influenced by the physiological age of the tissue and could not be ascribed to the genetic backgrounds within the su1 genotypes.
Tetrasomic Inheritance of a Lethal Character in Medicago sativa L.1
Authors: Stringam G. R. , Elling L. J.
Published: July 2010

Inheritance of a lethal character in alfalfa was studied in several clones and their inbred progenies. It was concluded that the character is controlled by complementary dominant factors inherited tetrasomically. Le and Le2 have been designated as symbols for these factors. Crosses between inbred progenies from a duplex plant carrying Le or Le2 and a clone with the complementary simplex dominant genotype were studied. Progenies from these crosses segregated 3 normal:1 lethal, 7:5 or 1:1 the ratios expected with tetrasomic inheritance. No progenies produced all normal plants. Four of the 5 viable tetrasomic genotypes for each locus were isolated from inbred progenies and their frequencies fit the expected 1:8:18:9 ratio. Progenies of crosses among different known genotypes as identified by test crosses segregated 3:1, 7:5, 1:5, and 11:25 in agreement with predicted ratios. The plants in one cross were all lethal except for one. In some progenies lethality was typified by premature death. The data suggest a general relationship between gene dosage and frequency of the premature death.
Miniature Centric Fragment Chromosomes in Mutagen‐treated Pearl Millet, Pennisetum typhoides1
Authors: Powell Jerrel B. , Burton Glenn W.
Published: July 2010

A miniature centric‐fragment chromosome was observed in pearl millet, Pennisetum typhoides (Burm.) Stapf and C. E. Hubb., subjected to thermal neutron and ethyl methane sulfonate treatments. The very small chromatic particles oriented themselves at the metaphase I plate, and divided and moved to the poles at anaphase I, but were irregular in their behavior at anaphase II. Most plants with these centric‐fragment chromosomes were found in the thermal neutron treatments, with some in the ethyl methane sulfonate treatments, but none in the controls. One miniature centric‐fragment chomosome was the most common number present in microsporocytes of single plants, with the exception of one plant which contained two fragment chromosomes per cell. Size variation in the particles was noted in one plant. These miniature centric‐fragment chromosomes, discovered in mutagen‐treated pearl millet, may have an origin similar to the small ring chromosomes described in maize.
Inbreeding and Crossing in Autotetraploid Maize1
Authors: Levings C. S. , Dudley J. W. , Alexander D. E.
Published: July 2010

The effect of crossing and inbreeding was determined in autotetraploid maize for three characters, plant height, ear length, and ear weight. Rank of generation means for the three characters was in the order, double crosses > single crosses > F2 > F3 > lines. Regression analysis indicated that nearly all the variability among generation means could be accounted for by differences in level of inbreeding. Implications of these results for breeders of autotetraploid species were discussed.
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).
Effect of Kernel Position on Oil Content in Corn (Zea mays L. )1
Authors: Lambert R. J. , Alexander D. E. , Rodgers R. C.
Published: July 2010

Amount of oil per kernel in maize is affected by position on the ear. Kernels highest in oil are located at mid‐ear position. Due to larger mass, the basal kernels possess a greater total amount of oil than the kernels of the central and tip positions.
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.
Revised Method for the Preparation of Standards in the Sodium Picrate Assay of HCN1
Authors: Gilchrist D. G. , Lueschen W. E. , Hittle C. N.
Published: July 2010

The proposed revised sodium picrate assay method relies on recovery rather than solution standards. The recovery standards are prepared by releasing HCN from stock cyanide solutions, recovering the HCN on alkaline picrate paper strips, followed by elution in distilled H2O.
Why Store Genetic Stocks?
Authors: James Edwin
Published: July 2010

Genetic collections qualify for storage at the National Seed Storage Laboratory. Advantages in using this facility are: (1) collections are maintained intact with continuing high viability; (2) seed distribution to interested scientists is made on request; (3) the depositor is kept informed as to the viability of collections; and (4) the Laboratory assumes the responsibility through contract arrangements for reincreases in case viabilities decline.
Rates of Germination and Tube Growth of Stored and Fresh Alfalfa (Medicago sativa L.) Pollen on Agar Medium
Authors: Lehman W. F. , Puri Y. P.
Published: July 2010

Rate of germination and tube growth of fresh and stored pollen were studied in vitro. First germination occurred in all samples after about 10 minutes of incubation. With fresh pollen maximum germination was reached at 1 to 2 hours. Stored pollen which varied in age from 42 to 101 days, differed in response. Germination of one sample (64 days old) was similar to that fresh pollen. Other samples germinated more slowly and required 2 hours or longer to reach maximum germination. Growth patterns of pollen tubes were similar for all samples. Growth was slow for about the first 45 minutes and then appeared to be in a straight line relationship with time. Highest average correlation coefficient was between tube length and time (0.95) and lowest between tube length and germination (0.49).