bluuebunny/crossref_metadata_2025 huggingface dataset:
Meiotic Irregularities in Hybrids Between Diverse Genotypes of Tall Fescue (Festuca arundinacea, Schreb.)1
Authors: Evans G. M. , Asay K. H. , Jenkins R. G.
Published: July 2010

Hybrids between American and North African Festuca arundinacea genotypes were characterized by numerous multivalents and univalents at first metaphase of meiosis and, consequently, were sterile. This was most likely due to differences in the arrangement of genetic material in the two parental groups. On the other hand, meiosis in progeny of crosses between American and European (French and Dutch) genotypes was much more regular with only one translocation evident.

The sterility barrier imposed by the karyotypic divergence of American and North African genotypes seriously limits breeding efforts to combine desirable attributes of each. However, the relatively minor difference between European and American stocks should not impose any limitation on their inclusion in new synthetic varieties.
Effects of Deheading on Stalk Yield and Juice Quality of Rio Sweet Sorghum1
Authors: Broadhead Dempsey M.
Published: July 2010

The carbohydrates in the grain normally produced by sweet sorghum [Sorghum bicolor (L.) Moench.] would more valuable to a sugar producer as sugar in the juice of the plant. April 1, May 1, and June 1 plantings of ‘Rio’ were deheaded in the boot and flower stages of head development. Deheaded and normal plants were compared when the normal plants were in the milk, dough, and rip stages of grain development to determine the effect of deheading on stalk yield and juice quality.

Deheaded plants were higher in Brix, sucrose, and starch, but they contained less juice than normal plants. The effects of deheading on juice extraction, Brix, sucrose, and starch were similar for the milk, dough, and ripe stages of grain development. Deheading in the boot stage resulted in a slightly greater increase in sucrose than deheading in the flower stage. Plants deheaded in the boot and flower stages were similar in yield of stalks, juice extraction, Brix, starch, and juice purity. Deheading did not affect stalk and sugar yield or juice purity. Deheaded plants lodged less and had more side branches than normal plants.
The Effect of (2‐Chloroethyl) Trimethyl Ammoniumchloride (CCC) and Gibberellic Acid (GA) on Ribonucleic Acid and Protein Concentration of Wheat Plants1
Authors: Bokhari Unab G. , Youngner Victor B. , Young Roy E.
Published: July 2010

Protein and RNA concentrations of wheat (Triticum aestivum L.) plants were studied in relation to treatments with the growth retardant (2‐chloroethyl) trimethyl ammoniumchloride (CCC) and gibberellic acid (GA3). Eleven days after CCC application as a soil drench, internode RNA concentrations were increased by all CCC concentrations used (10−1 to 10−3 M), but leaf RNA concentrations were increased only by CCC levels of 10−1 to 10−3 M. Internode protein concentrations were increased by CCC levels of 10−3 to 10−6 M and leaf protein concentrations by 10−1 to 10−5 levels. Twenty‐one days after soil drench treatments, leaf RNA concentrations were increased by CCC levels of 10−1 to 10−5 M and internode and leaf protein concentrations were increased by all CCC levels. High concentrations of CCC (10−2 to 10−5 M) applied to the roots in Hoagland's solution reduced RNA and protein concentrations and low CCC levels (10−6 to 10−8 M) increased them. An addition of 10 µg/ml of GA3 caused RNA and protein concentrations to increase greatly at the lower CCC levels. High concentrations of CCC may have an inhibitory effect on RNA and protein synthesis resulting from a reduction‐in GA or GA‐like substances. The effect of low CCC concentrations may be independent of growth regulators.
Computer Simulation of Dry Matter Distribution During Sugar Beet Growth1
Authors: Fick G. W. , Williams W. A. , Loomis R. S.
Published: July 2010

Seasonal growth curves of sugar beet (Beta vulgaris L.) were simulated by a CSMP computer model called SUBGRO. The hypothesis on which the simulations were based was a hierarchy of priorities for photosynthate partitioning. In order of importance, these priorities were as follows: respiration, top growth, fibrous root growth, and storage root3 growth including sucrose acculation. Simulations agreed well with field observations when these priorities were used. Simulated growth did not match field observations if the sequence was changed. The rate of use by each sink was further regulated by its growth potential and by its environment. Functional leaf and fibrous‐root surfaces played key roles in regulating the growth rates through a quantitatively expressed set of partitioning functions. To test the partitioning hypothesis, simulated recovery patterns from partial defoliation or root pruning were compared to experimental observations. Simulated recovery was similar to that of real plants.
Single Height‐Gene Effects in Hybrids of Doubled Haploid Sorghum bicolor (L.) Moench1
Authors: Schertz K. F.
Published: July 2010

Effects of a single height gene were determined in 2‐dwarf vs 3‐dwarf and in 3‐dwarf vs 4‐dwarf sorghum (Sorghum bicolor (L.) Moench) hybrids. Characteristics among hybrids of ‘ATx3197’ and ‘ATx3118,’ each crossed to a short line, were compared to two tall mutant lines derived from a doubled haploid. Among the hybrids with a specific female parent, those from the tall male parents exceeded those from the short male parent in height and kernel weight. Females ✕ males interactions were noted for height and kernel weight. Among the A3197 hybrids,those from tall male parents had a greater yield than those from the short male parent. Hybrids from the two tall mutant lines also differed in weight of kernels from main panicles. Most characteristics for which tall and short hybrids differed were the same as those noted to differ among these male parents when they were lines in previous studies.
Seed Dormancy, Germination Environment, and Seed Structure of Lehmann Lovegrass, Eragrostis lehmanniana Nees1
Authors: Wright L. Neal
Published: July 2010

Seed of the cultivar ‘A‐68’ and 36 lines of Lehmann lovegrass, Eragrostis lehmanniana Nees, were investigated to identify and characterize seed (caryopsis) dormancy with respect to determination of pattern and degree. Development of the optimum germination environment and study of seed structure were emphasized. Freshly harvested seed varied among lines from no dormancy to complete dormancy. Dormancy decreased in a linear pattern for 100 weeks after harvest. Cylinder scarification was the most effective and simplest to control of all treatments to overcome dormancy. Many treatments were not effective. Optimum germination environment consisted of alternating temperatures of 20 C with 16 hr of darkness and 30 C with 8 hr of light with Eaton and Dikman no. 617 or Whatman no. 2 filter paper substrate. Differences were not observed in the origin of structural parts of the fruit coat among lines. Dry weights of water‐extractable gelatinous seed‐surface were not related to seed dormancy and removal of the gelatinous seed‐surface did not overcome seed dormancy. Variability was found among lines for presence and quantity of known, identified, and unidentified chemical compounds of seed extracts. Seed dormancy differences were not attributable to chemical differences of eed extracts.
The Inheritance of Several Agronomic and Fiber Properties Among Selected Lines of Upland Cotton, Gossypium hirsutum L.1
Authors: Baker Jerry L. , Verhalen Laval M.
Published: July 2010

A quantitative genetic study of lint yield, earliness, lint percent, 2.5 and 50% span length, uniformity index, fiber fineness, and fiber strength was conducted in upland cotton, Gossypium hirsutum L., utilizing the Jinks‐Hayman diallel analysis. Ten selected lines and their 45 possible F1 combinations in 1969 and 1970, plus the 45 corresponding F2's in the second year, were included in randomized, replicated experiments at a single location.

Analyses of variance indicated highly significant differences among entries for all traits in both years. Partial failures of the diallel assumptions were noted for each trait, although some traits did more nearly comply with those assumptions than did others. Epistasis was not detected as a significant factor for any of the traits. A genotype by environment interaction for the additive components of variation was observed for lint yield, lint percent, and 2.5% span length. The dominance relationships among parents were not constant over years for earliness, lint percent, 2.5% span length, fiber fineness, or fiber strength. Multiple allelism was shown by all traits except fiber fineness; however, gene correlations and parental heterozygosity were not (or could not be) detected for any trait.

Overdominance governed lint yield, earliness, lint percent, 50% span length, and uniformity index. Partial dominance was operative for fiber fineness, and complete dominance was indicated for 2.5% span length and fiber strength. Narrow‐sense heritabilities indicated that mass selection should be effective for improving 2.5% span length, fiber fineness, and fiber strength among lines in this material and somewhat less effective for improving earliness, lint percent, 50% span length, and uniformity index. Alternatives, such as pedigrees, sib tests, and progeny tests, must be considered to achieve genetic progress for lint yield in this material.
Intra‐Plant Variation for Pollen Production in Male‐sterile and Fertile Alfalfa1
Authors: Barnes D. K. , Garboucheva Rada A.
Published: July 2010

In Medicago saliva L. intra‐plant variation in pollen production occurred in partially male‐sterile clones, but it was not associated with either flower position on the plant or sampling date. The variation occurred at random throughout the plant. Anthers within the same flower varied for both number of pollen grains and percentage of normal pollen grains.

The average number of pollen grains per anther varied among clones from about 440 to 850. The free anther had only about two‐thirds as many pollen grains as each of the remaining nine anthers. The number of normal pollen grains correlated with visual estimates of the amount of dehisced pollen, r = .854**, 11 d.f. Pollen abortion in male‐sterile plants apparently reduced internal pressure sufficiently to prevent rupture of the anther wall and extrusion of pollen.
Plant Measurements as Indicators of Crop Water Deficit1
Authors: Clark R. N. , Hiler E. A.
Published: July 2010

An irrigation experiment was conducted with southern peas [Vigna sinensis L. (Endl.) var. ‘Burgundy’] utilizing lysimeters in which the soil water balance could be controlled. The purpose of the experiment was to compare certain plant measurements as indicators of crop water deficit. Plant measurements made on stressed and non‐stressed plants throughout the growing season were leaf‐water potential, leaf‐air temperature differential, and leaf‐diffusion resistance.

Leaf‐water potentials were measured by the pressure chamber method on well‐exposed leaves. Leaf temperatures were measured by infrared radiometry and a diffusion porometer was used to measure leaf‐diffusion resistance. Tensiometers were used to determine the soilwater potential and to time the irrigations.

The plant response data taken throughout a day were sensitive to water deficits during the late vegetative stage; however, the measurements were less responsive when the leaves aged, indicated by plants in the pod development stage. The change was particularly evident in the leaf‐water potential measurements. All three plant measurements did indicate water deficit to some degree. Leaf‐diffusion resistance was the least responsive, and leaf‐water potential was the most responsive. Results relating leaf‐water potential to leaf‐diffusion resistance and soilwater potential are also given.
Comparison of Three Methods of Recurrent Selection in Maize1
Authors: Horner E. S. , Lundy H. W. , Lutrick M. C. , Chapman W. H.
Published: July 2010

Concurrent recurrent selection experiments were conducted for five cycles to compare three methods of selection for grain yield in maize (Zea mays L.): (1) combining ability with an inbred line (Inbred Tester Method), (2) combining ability with the broad‐base parental population (Parental Tester Method), and (3) yield S2 lines per se (S2 Progeny Method). The 15 selected populations were then crossed with the parental population and with another broad‐base synthetic to evaluate changes in general combining ability, and also were tested as randommated and selfed populations per se.

A significant linear increase in general combining ability over cycles was obtained for all methods, but the Inbred Tester Method was significantly more effective than the other two methods (4.4% gain per cycle, compared with 2.4 and 2.0% for the Parental Tester and S2 Progeny Methods, respectively). There was no significant difference among methods for yield of random‐mated selected populations when adjustments were made for differences in rate of inbreeding.

The results indicate that the inbred tester used was homozygous recessive at many important loci. This would result in larger testcross variances and more successful selection of dominant favorable alleles than is possible with a broad‐base tester, which probably has intermediate gene frequencies at most loci. The slow progress in combining ability improvement with the S2 Progeny Method suggests that this method also was not effective in fixing dominant favorable alleles.
Evidence for a Trifluralin‐Potassium Nitrate Interaction Affecting Tomato Seedling Growth1
Authors: Barnes L. W. , Krieg D. R.
Published: July 2010

The influence of various potassium nitrate (KNO3) concentrations on herbicidal activity of trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) was investigated using hydroponically grown tomato (Lycopersicon esculentum Mill. cv. ‘Homestead 24’) seedlings. The treatments consisted of all combinations of 0.0, 0.5, and 1.0 mg trifluralin/liter and 0, 15, and 30 meq KNO3/liter added to the base nutrient solution. Treatment was initiated when the third true leaf began expanding and lasted for 1 week. The addition of trifluralin to the base nutrient solution reduced fresh weight, dry weight, leaf area, chlorophyll concentration, and photosynthetic rate. The addition of 15 meq KNO3liter to the herbicide treatments further reduced these same parameters when compared to the herbicide alone. The addition of 30 meq KNO3/liter to the herbicide treatments increased the growth of the seedlings to levels comparable to, or in excess of, the herbicide alone.
Characterization of Freezing Inhibitors from Winter Wheat Cultivars1
Authors: Shearman Linda L. , Olien C. R. , Marchetti B. L. , Everson E. H.
Published: July 2010

The activity of freezing kinetics inhibitors was characterized by a visual rating technique for several wheat (Triticum aestivum L.) cultivars. The procedure allowed a single test of a cultivar with a minimum of 13 g of seed, and 10 tests per day with the equipment available. Comparisons between several replications of kinetic inhibitor ratings and cultivar survival of high‐intensity freezing showed expected relationships. The activity of kinetic inhibitors from some cultivars was commensurate with survival ability. However, other cultivars exhibited better kinetic inhibitor activity than indicated by their survival rating. The ability to identify cultivars with high activity with no confounding effect by plant weaknesses in other areas that can affect survival, is a distinct advantage of this test. All wheat cultivars tested had lower ratings than ‘Rosen’ rye, the standard for the maximum rating. A large number of cultivars with varied genetic backgrounds are now being screened for improved kinetic inhibitor activity using this technique.

As an initial inquiry leading to the screening technique, the validity of using seed as the polysaccharide source in the kinetic inhibitor tests was substantiated by hydrolysis and chromatography. Monosaccharide components were similar for polysaccharides extracted from crown tissues, the important area of freezing resistance, and from seed tissue. Purifying the polysaccharide extracts has proved difficult. In the best preparations, no compositional differences were seen between those polysaccharides exhibiting activity as kinetic inhibitors and those showing inactivity.
Growth of Alsike Clover Pollen In Vitro1
Authors: Benner L. R. , Townsend C. E.
Published: July 2010

Pollen germination and pollen tube elongation in vitro and their relationship to self‐incompatibility were investigated in diploid alsike clover (Trifolium hybridum L.). Of four culture media evaluated, the most suitable one contained 25% (w/v) sucrose, 100 ppm of CaCO3 and 50 ppm of H3BO3 in deionized distilled water. Pollen germination was 82% and average pollen tube length was 0.43 mm after 24 hours at room temperature. Pollen tube elongation was approximately 10% of that necessary to effect fertilization. In a subsequent study, sucrose concentration of the selected medium was varied as follows: 10, 25, and 35% (w/v). Pollen germination was best (92%) in the solution containing 35% sucrose, but pollen elongation was best (0.41 mm) in the 25% sucrose solution. Pollen germination and pollen tube elongation were the poorest at the 10% sucrose concentration. Germination and tube elongation appeared to be two separate processes with different nutritional requirements.

Pollen from 25 plants representing 11 S‐allele genotypes was evaluated in vitro for percentage germination and tube elongation. Although there were differences among genotypes and among plants within genotypes for these characters, no relationship was established between pollen grain nutrition and S‐allele genotype. Tube elongation sufficient to effect fertilization was not obtained.
Evaluation of Intergenotypic Competition with a Paired‐Row Technique1
Authors: Fehr W. R.
Published: July 2010

A paired‐row technique was developed to measure intergenotypic competition between soybean (Glycine max (L.) Merr.) cultivars. A paired‐row plot consisted of two rows spaced 8 cm apart, the closest that we were able to grow soybeans in Iowa and still distinguish the individual rows at harvest. Different paired‐row plots were grown 1 m apart. To evaluate the competitive interaction of two soybean cultivars, three paired‐rows are needed per replication, one where the cultivars compete and one for each of the two cultivars in pure stand.

Intergenotypic competition in paired‐rows was compared with that in a 1:1 blend grown in a single‐row plot for nine cultivar pairs. A cultivar with tawny pubescence and a cultivar with gray pubescence were selected for each blend to permit separation of the cultivars at maturity. The individual cultivars were harvested separately in both the paired‐rows and the 1:1 blend, and their yield performance was compared with that in a pure stand.

The paired‐row technique was effective for determining the good and poor competitors in a blend for every cultivar pair tested. The percentage yield increase or decrease of each cultivar in competition generally was similar in the blend and the paired‐rows. The data suggested, however, that growing cultivars in rows only 8 cm apart did not perfectly simulate the competitive interactions that occur in a 1:1 blend.
Relationship between Genotype‐Environmental Interaction and Stability Parameters
Authors: Marquez‐Sanchez Fidel
Published: July 2010

Phenotypic models with and without genotype‐environment interaction (γĲ) are represented graphically. For a variety that is planted in several environments the model without interaction is represented as a regression line of phenotypic values on environmental indices, with a slope equal to one and no deviations from regression. In the model with interaction neither of these conditions is fulfilled. The interaction term γĲ is the deviation of actual phenotypic values from the regression line with slope equal to one, and δĲ is the deviation of the phenotypic values from the adjusted regression line with slope different from one. A stable variety is defined as one which does not interact with environments.
Effect of Temperature on Self‐ and Cross‐Compatibility and In Vitro Pollen Growth Characteristics in Alfalfa1
Authors: Dane Fenny , Melton Bill
Published: July 2010

Five selected alfalfa (Medicago sativa L.) clones were evaluated for self‐compatibility, cross‐compatibility, and pollen growth characteristics under four temperature treatments. Crosses were made with and without emasculation. An increase in temperature resulted in a decrease in self‐ or cross‐compatibility estimates. Field results were similar to those obtained at 32C in the growth chamber.

Clonal differences existed, but a highly significant clone ✕ temperature interaction for all characteristics measured showed that these clones would not be expected to perform the same in all environments. Cross‐ and self‐compatibility or male and female cross‐compatibility estimates were generally not correlated. Some plants performed differently as male and female parents. Female cross‐compatibility was correlated between 21 and 27C and between 27C and the field study temperatures. Higher correlations were found for male cross‐compatibility values from the different temperature regimes. The cross‐compatibility estimates from the crosses produced with and without alcohol emasculation were not correlated. Pollen germination was affected by the temperatures at which the plants were grown, whereas pollen tube elongation was affected more by incubation temperatures. Male cross‐compatibility was correlated with pollen germination.
Evaluation of Hard Red Spring Wheat (Triticum aestivum L.) Breadmaking Quality Characteristics by Utilizing a Minimum Standard Method1
Authors: Mokhtarzadeh A. , Busch R. H. , Shuey W. C.
Published: July 2010

Cultivar responses to environments for test weight, 1000 kernel weight, wheat mineral, and mixing time were determined for seven commercially grown wheat (Triticum aestivum L.) cultivars in 57 Uniform Regional Spring Wheat Nurseries (URSWN) from 1964 through 1967. The analysis was not applicable to small and large kernel sizes or to dough characteristics because of nonlinear responses to environments.

We determined that four minimum standard check cultivars were needed to evaluate wheat for most environments from the 1964 to 1967 data. These minimum standard check cultivars were then used for 1968 and 1969 URSWN data, with a weighted evaluation score for each trait, to evaluate 10 strains and cultivars. This new minimum standard method appeared to offer the following main advantages over the present procedure used to evaluate potential varieties: 1) it considers the responses of check cultivars to environments; 2) it places quality evaluations on a minimal standard base for a comparison among breeding lines; 3) it provides a statistical test of the mean minimum evaluation scores; and 4) if economic weights of each quality trait were available, it would indicate economic worth of a selection to industry.
Protein Quality and Kernel Properties of Modified Opaque‐2 Endosperm Corn Involving a Recessive Allele at the Sugary‐2 Locus1
Authors: Paez Alix V.
Published: July 2010

A maize (Zea mays L.) seed stock with a modified endosperm type was isolated from a homozygous opaque‐2 line. Allelic tests with known single gene endosperm markers showed that the genotype was su2/su2, o2/o2. The genotypic constitution of this isolate was further confirmed by an allelism test with two known double recessive types as su2/su2,o2/o2, testers. The endosperm had a higher percentage of lysine per unit of protein than both the typical opaque‐2 endosperm corn used as a check and those values reported in the literature. The endosperm of this stock is translucent, of hard texture, and somewhat discolored and dull; it has a kernel density similar to the normal endosperm corn. Kernel weights of the S2 progenies segregating at the su2/su2, and o2/o2 loci indicated that the kernel weight of the double mutant endosperm combination su2/su2,o2/o2 was 92 to 93% of that of the opaque‐2 class. The differences in kernel weights were explained as the results of the effects of the opaque‐2 gene on the sugary‐2 endosperm types which are already below the mean of normal endosperm corn. Observed kernel weight variability between and within progenies suggested the possibility for selection of kernel weights within the levels of sugary‐2 as well to levels similar to normal and opaque‐2.

The double recessive type (su2/su2,o2/o2) had increased lysine as percent of protein and improved kernel properties in comparison to opaque‐2 corn.
Relationships Between Yield and Several Yield Components in a Set of Maize Hybrids
Authors: Johnson G. R.
Published: July 2010

The relationship of yield to yield component estimates obtained from additive, additive plus dominance, and additive plus dominance plus epistasis models of inheritance was examined in a set of 15 single cross and 30 three‐way maize (Zea mays L.) hybrids, derived from a group of 6 commercially adapted, essentially homozygous inbred lines. The yield components considered were: row number, kernels per row, and weight per 300 kernels. Yield component estimates from each genetic model were converted to logarithms and used as independent variables in a multiple linear regression analysis in which log yield was the dependent variable.

A model including additive effects of row number and weight per 300 kernels and additive plus dominance effects for kernels per row adequately accounted for the variation in yield due to variability in these components. Maximum yield with regard to additive effects was characterized by high row number and weight per 300 kernels, whereas yield response to dominance effects was due to kernels per row only.

These results indicated that yield response to nonadditive effects was maximized by crosses among lines that, on the basis of additive effects, exhibited high row number and weight per kernel. However, the additive effects yield component estimates provided no more information concerning yield than did the additive effects estimate of yield itself. Therefore, estimates of the additive yield component effects of the parental lines would not have been useful in predicting crosses possessing favorable nonadditive effects in this set of hybrids. In addition, because the yield components exhibited at least as much nonadditive variation as yield, yield component estimates obtained from the inbreds themselves would probably not have been of much more use in predicting hybrid performance than inbred yields themselves.
Respiration during Drying of Alfalfa Herbage1
Authors: Wolf D. D. , Carson E. W.
Published: July 2010

Respiration in harvested alfalfa (Medicago sativa L.) herbage was inactivated by tissue temperatures above 55 C for 15 minutes and by desiccation to about 60% dry matter. Microwave heating for 30 seconds caused the temperature of the tissue to exceed that needed to inactivate respiration. Relative concentration of nonstructural carbohydrates in tissue exposed to microwaves was similar to freeze‐dried tissue. Microwave treatment followed by oven‐drying minimized respiration losses and would, therefore, improve the quantitative data on chemical composition.
Inheritance of Phytophthora Root Rot Resistance in Alfalfa1
Authors: Lu Nancy Shyh‐Jane , Barnes D. K. , Frosheiser F. I.
Published: July 2010

The inheritance of Phytophthora root rot resistance was determined in alfalfa (Medicago sativa L.) for five clones from the variety ‘Lahontan’ and six clones from ‘Vernal’ and Vernal‐type varieties. A heterozygote‐diallel crossing scheme was used as the basis for genetic analysis. Parent clones were selfed, intercrossed, and testcrossed to two susceptible clones. Degree of resistance was determined by type of root‐rot lesion. Susceptibility appeared to be conditioned by one tetrasomic gene, Pm, with incomplete dominance. The nulliplex condition produced highly resistant plants. The simplex condition produced a moderate degree of resistance. Duplex, triplex, and quadruplex plants were increasingly more susceptible. Resistance in the Lanhontan and Vernal‐type varieties appeared to be controlled by the same gene.
Stubby Head, an Induced Facultative Apomict in Pearl Millet1
Authors: Hanna W. W. , Powell J. B.
Published: July 2010

Stubby head is a multi‐ovary, ‐ovule, ‐embryo sac mutant induced in pearl millet (Pennisetum typhoides (Burm.) Stapf. and Hubb.) by a dual treatment of the thermal neutrons and diethyl sulfate. The mutant has shortened internodes and flattened stems and produces a rosette of leaves around a stubby inflorescence. Cytological tests and progeny tests indicate that it is a facultative apomict. This mutant could make a significant contribution to the improvement of pearl millet if it can be developed into a usable form.
Agronomic Characteristics of Near‐Isogenic Tall and Semidwarf Lines of Durum Wheat1
Authors: Joppa L. R.
Published: July 2010

Semidwarf genes from ‘Norin‐10’ and other semidwarf varieties have been used widely in breeding high‐yielding hexaploid wheats (Triticum sp.). These genes also have been transferred to tetraploid durum wheat (Triticum turgidum L.). The effect of the semidwarf genes on eight agronomic characteristics of durum wheat were investigated at two locations in each of 2 years, using paired tall and semidwarf near‐isogenic lines. The semidwarf genes and their associated linkage blocks reduced test weight, kernel weight, and height; increased days to heading and number of culms/ha; but did not affect yields, kernels/spike, or grain/straw ratios. Semidwarf lines with adequate test weights and kernel weights were observed in some crosses. Acceptable semidwarf varieties of durum wheat can be produced if the plant breeder selects carefully for high test weight and kernel wieght.
Propagation of Reed Canarygrass (Phalaris arundinacea L.) from Culm Segments1
Authors: Hovin A. W. , Beck B. E. , Marten G. C.
Published: July 2010

Development of hybrid cultivars of reed canarygrass (Phalaris arundinacea L.) necessitates vegetative increase of clones selected as parents. Our objectives were to determine the effects of genotypes, stage of growth, and treatment with ethephon (2‐chloroethylphosphonic acid) on the establishment of stands from nodes of reed canarygrass culm segments. We established 12 genotypes (clones) from fixed quantities of culms with attached leaves chopped into 10 cm lengths. Satisfactory stands of all clones resulted when at least 0.4 kg/m2 of chopped material was covered with soil and irrigated, provided that culms were from sufficiently mature plants. Differences among clones in the number of established plants were highly significant.

Maturity affected establishment, in that cutting of culms at or before anthesis usually resulted in stand failure, whereas cutting at postanthesis to seed shattering stages resulted in satisfactory stands. Nonheading clones with 3.5‐month‐old culms also provided viable nodes. More shoots with larger roots were established from basal nodes than frcm apical nodes of culms at various growth stages.

Treatment of chopped culms of one nonheading clone with ethephon at 100‐to 1,000 ppm rates resulted in higher stand density than that of the untreated check. Ethephon suppressed density when one clone was similarly treated at the seed shattering stage.

Our results indicated a general lack of relationship between tillering capacity (expressed as plant width) and stand establishment from culm sections of 64 clones (r = −0.20). The results suggested that tillering and nodal activity must both be considered before planting rates can be established for parent clones intended for field‐scale crossing in hybrid development.
Example of the Effects of Early Season Frost Damage on Yield of Corn
Authors: Arny D. C. , Upper C. D.
Published: July 2010

Nondamaged corn (Zea mays L.) plants yielded significantly more (about 8,500 kg/ha) than plants in the same field showing six or more damaged leaves per plant (about 6,000 kg/ha) as a result of a frost on June 23, 1972. No plants in any of the plots were killed. Kernel weights were 69 (nondamaged) and 61 (damaged) g/200 kernels. Maturity was also delayed as indicated by later tasseling and higher (30%) moisture content of ears in damaged plots than in nondamaged (27%) at harvest.
Grass Seed Harvester for Small Plots1
Authors: Smith Rex L.
Published: July 2010

A seed‐head harvester consisting of a gasoline‐powered hedge trimmer and an aluminum tray is described. This harvester greatly facilitates harvesting grass seed of small research plots and reduces labor requirements to one‐fifth that of hand harvesting.
Seed Divider for Plot Planters1
Authors: Clark R. C. , Fehr W. R.
Published: July 2010

A seed divider was constructed for mechanized plot planting. It does not require a source of power and can be used effectively when planting on uneven terrain. The divider was built from a modified Boerner sampler. Seed for each row of a plot is sampled from the entire perimeter of the sampler so that the divider works effectively when it is level or on an angle.

The divider can be used without stopping between plots. As one plot is planted, the seed for the next plot is poured into the seed divider. The seed passes by gravity through the divider to funnels on planting units where it is held until the funnels are trapped.

The divider has been tested with soybeans (Glycine sp.), wheat (Triticum sp.), and barley (Hordeum sp.).
Effects of Low Non‐Freezing Temperatures on Chlorophyll Accumulation In Corn and Other Grasses1
Authors: Gallopin Isable Gomez , Jolliffe Peter A.
Published: July 2010

Chlorosis developed in leaves of 7‐day‐old seedlings of five grass species following a 12‐hour, 10 C treatment, and in leaves of three additional species after a 12‐hour, 5 C treatment. In corn (Zea mays L.), low‐temperature induced chlorosis was reversed by returning to 25 C after 4 or 8 hours at 10 C. Sprays of cytokinins of 5,6‐dihydro‐2‐methyl‐1,4‐3‐carboxanilide (Carboxin) moderated, but did not eliminate, the adverse effects of cold treatment on corn.
Evaluation of the Effectiveness of Polycross‐ and Self‐Progeny Tests in Increasing the Yield of Alfalfa Synthetic Varieties1
Authors: Busbice T. H. , Hunt O. J. , Elgin J. H. , Peaden R. N.
Published: July 2010

Selection for forage yield based on polycross‐ and selfprogeny performance was practiced on two broadbased alfalfa (Medicago sativa L.) populations by selecting the best 10% as parents for experimental synthetic varieties. Random samples of 60 plants from populations A and B were assessed for breeding value to compare the efficiencies of the polycross‐ and the self‐progeny test methods. The best six plants from each population and from each test method were selected as parents for synthetic varieties. The Syn 2 generations of several experimental synthetics were evaluated near Raleigh, N. C.; Reno, Nevada; and Prosser, Washington. Selection based on both methods of progeny testing was ineffective in increasing yield. The study indicated the importance of genotype ✕ environment interactions on selection experiments.
Effect of 2‐Chloroethylphosphonic Acid (Ethephon) on Female Fertility of Two Wheat Varieties1
Authors: Rowell P.L. , Miller D.G.
Published: July 2010

Female fertility was determined in greenhouse and field‐grown chemical male‐sterile lines (C‐lines) of wheat (Triticum aestivum L.) following application of 2‐chloroethylphosphonic acid (Ethephon) as a gametocide. In greenhouse studies, number of seed per spike and percent of F1 hybrid seed produced on C‐lines did not differ significantly from male‐sterile B‐lines following hand pollination for both lines. At pre‐, early, mid‐, and late boot stages, all rates of Ethephon resulted in 87% or more F1 seed. Progeny from seed set on plants treated in the field in 1970 and 1971 showed that the percent outcrossing ranged from 5 to 100%. Based on the percent hybrid seed obtained, the optimumst ages for field application in ‘Nugaines’ wheat were pre, early, and midboot at chemical dosages of 1,500 to 3,000 ppm. Sensitivity to Ethephon treatment appeared to be greater in the greenhouse than in the field. Under field conditions significant increases in seed set on nonbagged spikes over that of bagged spikes for field grown C‐lines were shown. This observation coupled with the significant occurrence of hybrid seed produced on C‐lines grown in the field or in the greenhouse indicate that female fertility was high following chemical sterilization by Ethephon
Evaluation of Methods Used in Computing Net Assimilation Rates of Soybeans (Glycine max (L.) Merrill)1
Authors: Buttery R. R. , Buzzell R. I.
Published: July 2010

Calculation of mean net assimilation rates (NAR) soybeans (Glycine max (L.) Merr.) using the Briggs, Kidd and West equation (assuming plant weight (w) and leaf area (l) were linearly related) gave values very similar to those obtained when allowance was made for α (in the equation w = k + mlα). The regression method for estimating NAR involves fitting curves of the type loge w = a + bt + ct2 and loge l = a1 + b1t + c1t2. Residuals in these regression equations (observed — calculated values) were significantly affected by both plant population and cultivar, and the NAR's calculated from these regressions reflected this bias.
Seed Development Following Matings of Trifolium nigrescens ✕ T. occidentale at Different Ploidy Levels1
Authors: Chen Chi‐Chang , Gibson Pryce B.
Published: July 2010

Fertilization ensued from all matings obtained by pollinating diploid and autotetraploid Trifolium nigrescens Viv. with pollen from diploid and autotetraploid T. occidentale Coombe. However, only fertilized ovules from the cross of T. nigrescens (2x) ✕ T occidentale (4x) appeared to be developing successfully toward viable seed; fertilized ovules from other crosses aborted at early stages of development. Seed failure in the different crosses followed a similar pattern. The first evidence of abnormality was slow development of the endosperm. Sequentially, the endosperm failed to develop signs of specialization, such as formation of a haustorium, and signs of breakdown followed in 1 or 2 days. The embryo began to degenerate when the endosperm was in a highly collapsed state. Concomitant with failure of the embryo and endosperm, abnormalities occurred in the adjacent maternal tissues. The endothelial cells stained darkly, whereas the integumentary cells showed little breakdown from digestion which characteristically has occurred at this time in normal seed development. These observations indicate that lack of a functional endosperm blocks the process of food transfer from the maternal tissues to the young embryo, thus causing nutrients to accumulate in the endothelium. Consequently, the embryo starves. However, the observation of a welldeveloped endosperm when either the egg was not fertilized or the zygote did not divide in two exceptional seed from the cross T. nigrescens (2x) ✕ T. occidentale (2x) suggests the possibility that the hybrid embryo was involved in endosperm failure.
Comparative Grain Yields of Corn Hybrids in Normal and in Texas Male‐Sterile Cytoplasm (cms‐T) Infected with Helminthosporium maydis Race T and Disease Components of cms‐T Corn Hybrids1
Authors: Lim S. M. , Hooker A. L. , Kinsey J. G. , Smith D. R.
Published: July 2010

The amount of Helminthosporium maydis (Nisikado and Miyake) race T infection on corn (Zea mays L.) hybrids with Texas male‐sterile cytoplasm (cms‐T) (resulting from artificial inoculation or from natural infection) was significantly greater than on their normalcytoplasm counterparts. Early infection of cms‐T corn hybrids after artificial inoculation was significantly more severe than infection which took place naturally later in the season. Both 1,000‐kernel weight and grain yield of artificially inoculated cms‐T corn hybrids were reduced significantly more than those from the same cms‐T hybrids exposed only to natural infection. Grain yields and 1,000‐kernel weights of most cms‐T corn hybrids, exposed only to natural infection, were significantly reduced in relation to their normal‐cytoplasm counterparts even though the epiphytotic was delayed until late during physiological maturation of the plants. In the same field, however, there was no significant difference in grain yield or in 1,000‐kernel weight between cms‐T hybrids and their normal cytoplasm counterparts of highly resistant corn hybrids. Early infection, resulting from artificial inoculation, had no appreciable influence on amount of disease infection or on 1,000‐kernel weights of most normal‐cytoplasm hybrids. The amount of disease infection, grain yield, and 1,000‐kernel weight of cms‐T hybrids were significantly correlated with those of their normal‐cytoplasm counterparts. Cms‐T hybrids which had a high disease tolerance produced about twice as much grain as those of low tolerance in the presence of disease.

All disease components (leaf, sheath, and husk infection, and lesion sizes) were highly intercorrelated at each disease rating date: before silking, midsilk, and physiological maturity. The contribution of the lesion size component to the standardized regression weight () and incremental proportions of variance (ΔR2) values for reductions both in 1,000‐kernel weights and in grain yields was always higher than that of other disease components at each disease rating date. Lesion sizes measured at midsilk had higher and ΔR2 values in grain yield reduction than measurements before silking or at physiological maturity. The r values between lesion sizes and the entire plant infection were highest at each disease rating date.
Temperature‐Sensitive Mutants in Hordeum vulgare L.1
Authors: Kleinhofs A. , Warner R. L.
Published: July 2010

Chlorophyll content in the primary leaf of 76 viable chlorophyll‐deficient barley (Horedum vulgore L.) mutants was determined in seedlings grown at 10 and 26 C. The ratio of chlorophyll content at 10 C to that at 26 C (10/26 ratio) ranged from 0.05 to 8.00 in the mutants. The 28 mutants with ratios of 0.5 or less were considered to be cold‐temperature sensitive (cts) and the 16 mutants with ratios of 2.0 or greater were considered to be high‐temperature sensitive (hts). The remaining 32 mutants were classified as temperature‐insensitive (ti). Thirty‐four of the mutant genes have been located on specific chromosomes. Of these, 10 were cts, 8 ti, and 6 hts. The 10 cts mutant genes appeared to be widely distributed among the 7 chromosomes with all but chromosome 6 having at least 1 mutation. The six hts mutant genes were located on chromosomes 1, 2, and 5. The 18 ti mutant genes were located primarily on chromosomes 1, 2, 3, and 4 with chromosomes 5 and 6 having only 1 mutant gene each. Five of the mutant genes showed cytoplasmic inheritance. Of these, three were cts and two hrs. The cts mutants EMS 18, S 1, and Coast V, grown at 10 C, and the hts mutant, dES 26, grown at 26 C, were as lethal as albino seedlings grown at the same temperatures.
Changes in the Stomatal Response Characteristics of Grain Sorghum Produced by Water Stress During Growth1
Authors: McCree K. J.
Published: July 2010

Experiments were designed to test the hypothesis that stomatal response characteristics can be modified by growing the test plants under water stress. Different degrees of stress were obtained by varying the atmospheric demand and by allowing the soil to dry.

Hybrid grain sorghum (Sorghum bicolor (L.) Moench. CV. ‘Oro’) was grown in nutrient culture, under atmospheric conditions which simulated natural daily cycles of temperature and dew point, at constant light level and carbon dioxide concentration. Thirty days after planting, the diffusion resistances of fully expanded leaves were measured as functions of light level (at constant leaf water potential) and of leaf water potential (at constant light level), with the leaf temperature and ambient carbon dioxide concentration being kept constant. The responses of leaves grown in “hot, dry” and “warm, humid” atmospheric conditions were very similar to one another, but leaves which had been subjected to five cycles of moderate soil moisture stress, as well as ‘hot, dry’ atmospheric conditions, had stomates which were less responsive to decreasing leaf water potential than the stomates of leaves grown under well‐watered, conditions. These changes are in the right direction to explain differences which have been observed between growthchamber and field‐grown material.
Inheritance of Isocitratase Activity and Its Relationship to Seedling Vigor in a Cross of Upland Cotton1
Authors: Scholl R. L.
Published: July 2010

Seedlings of reciprocal F1, reciprocal backcross, and advanced generations of a biparental cross of Upland cotton (Gossypium hirsutum L.) were examined for isocitratase activity and axial fresh weight after 40 to 112 hours of germination.

Results from reciprocal hybrids after 40 and 112 hours of germination indicated that level of isocitratase activity and axial growth rate were maternally inherited, but there was no evidence of cytoplasmic inheritance. Wide segregation for isocitratase activity was observed in the F2 population after 40 and 112 hours of germination, and isocitratase activity appeared to be quantitatively inherited. In the Fz population, relative isocitratase activity of seedlings germinated 40 hours was highly correlated with the percent of seedling fresh weight in the axis (r=+0.843**). The association between the same two characters was small but negative for seedlings germinated 112 hours (r=−0.431**). The strength of the association between isocitratase activity and axial growth early in germination suggests that isocitratase activity may be a good indicator of early seedling vigor.
Epistasis in Maize (Zea mays L.): IV. Crosses Among Lines Selected for Superior Intervariety Single Cross Performances1
Authors: Stuber C. W. , Moll R. H.
Published: July 2010

Five quantitative traits in maize (Zea mays L.) were investigated to evaluate the statistical significance of epistasis as well as its importance in hybrid predictions in 18 sets of single, three‐way, and double crosses. Parental lines for the sets were selectively grouped based on superior specific combining ability evaluated in interpopulation single‐cross combinations. Although variability analyses failed to detect significant epistatic effects in yield and lodging, mean comparisons showed small but significant epistatic contributions in yield, ear number, plant height, and ear height.

Comparisons of the relative importance of errors caused by epistatic effects with those errors caused by genotype by environmental interaction effects in predicting hybrid performances were made. For yield, ear number, and ear height, predictions based on data from single environments showed greater discrepancies due to genotype by environmental interaction effects than to epistatic effects. Also, for yield and ear number, the use of single crosses to predict three‐way and double crosses in other environments was more reliable than the use of observed performances of three‐way and double crosses to predict their respective performances in other environments.
Slant‐Board Culture Methods for Root Observations of Red Clover1
Authors: Kendall W. A. , Leath K. T.
Published: July 2010

Red clover (Trifolium pratense L.) plants were grown to the flowering stage cultured on slant boards that were either irrigated continuously with a recirculating nutrient solution or watered twice daily when the roots were covered with bags of perlite. One irrigation system serviced many slant boards that were continuously wetted, whereas slant boards with perlite bags functioned independently. The latter method is best suited for treatments that might contaminate the irrigation system, such as pathogen treatments, and when several plant growth chamber or greenhouse environments are utilized. Both methods resulted in root systems that were free of solid substrate, readily available for treatments, and larger than comparable plant roots grown in soil. A weighing method that estimated water displacement provided a nondestructive measurement of roots and shoots of intact plants.