bluuebunny/crossref_metadata_2025 huggingface dataset:
Plant Regeneration from Hypocotyl‐ and Anther‐Derived Callus of Berseem Clover1
Authors: Mokhtarzadeh Ahmad , Constantin Milton J.
Published: July 2010

Plants were regenerated from hypocotyl and anther explains of berseem clover (Trifolium alexandrinum L.) on Murashige and Skoog (MS) medium containing various combinations of plant growth regulators. The most efficient production of plants from hypocotyl explants involved:

callus induction on MS medium with 1.0 mg/liter of naphthaleneacetic acid (NAA) and 1.5 mg/liter 6‐furfurylaminopurine (KIN);

callus increase on MS medium with 2.0 mg/liter of NAA and 0.1 mg/liter of N6‐(Δ2‐isopentenyl) adenine (2iP);

induction of shoots on MS medium with 0.5 mg/liter each of NAA and KIN followed by induction of roots on MS medium with 1.0 mg/liter of indoleacetic acid (IAA) and 0.1 mg/liter of 6‐benzylaminopurine (BAP). Suspension cultures in liquid MS medium containing 2.0 mg/liter of NAA and 0.2 mg/liter of 2iP provided filterable cell preparations with 45% viable cells, 4% of which gave rise to colonies within 3 weeks after transfer to agar plates. Shoot development was observed when callus from the colonies was cultured on MS medium with 0.5 mg/liter of NAA and KIN. Twenty percent of uncontaminated anthers from a single plant cultured on MS medium containing 1.0, 0.1, and 0.01 mg/liter of NAA, 2,4‐D, and 2iP, respectively, produced callus which could be maintained and from which plants could be regenerated by culturing on MS medium with 0.5 mg/liter each of NAA and KIN. Preliminary results indicate that cells of root tips from hypocotyl‐ and antherderived callus have the expected diploid and haploid number of chromosomes (2n = 16 and n = 8, respectively).
Yield Stability of Sorghum Random‐Mating Populations1
Authors: Kofoid K. D. , Ross W. M. , Mumm R. F.
Published: July 2010

With the advent of random‐mating populations in sorghum [Sorghum bicolor (L.) Moench], recurrent selection techniques are being utilized. The success of recurrent selection procedures depends on the yield level and yield stability of the base population to which the selection method is applied. To determine yield level and yield stability, four random‐mating populations (two fertility restoring or R and two fertility nonrestoring or B), eight population crosses (combinations of R ✕ B and B ✕ R), and two F1 hybrids were tested in five environments. Although no group was clearly the most stable, the F1 hybrids had the highest yield and their coefficient for the regression of yield on an environmental index was nearest to unity. However, their deviation from regression was significantly higher than the pooled error. The population crosses, having the second best yield level and regression coefficient, the smallest deviation from regression, and presumably, the largest genetic variance for yield, were judged to be the most stable group.

The analysis of variance showed significant differences for yield within the F1 hybrids, within the populations, and among the means of the F1's and the population material. In addition, a significant entry X environment interaction was found. This interaction was shown to be significant in its component terms of comparison ✕ environment (linear) among and within groups. These interactions indicated differences among and within groups for their response to a change in environment.

Within each population type, the wide based population with a larger genetic variance for yield was as stable as its narrower based counterpart. These wider based populations should respond successfully to population improvement techniques.
Nonstructure Carbohydrate and Dry Matter Relationship in Alfalfa Tap Roots1
Authors: Wolf D. D.
Published: July 2010

Total nonstructural carbohydrates (TNC) in the fleshy tap root are often used as an indicator of the physiological status of perennial forage plants such as alfalfa (Medicago sativa L.). TNC determinations involve considerable time and expense after the root samples are obtained. An alternative gravimetric method is pro. posed that involves determining percentage dry matter (DM). Tap roots are dug from the field, and the crown and lateral roots are removed. The remaining root is trimmed to a 10‐cm length, cleaned free of soil, and soaked in water for 2 hours. Root segments are blotted dry with paper towels and weighed (saturated weight). Roots are then oven dried and weighed (dry weight). Dry matter is expressed as a percentage of saturated weight.

Experiments conducted over 11 years under a wide range of varieties, plant ages, management practices, and sampling dates indicate highly significant correlations (r2 ranged 0.70 to 0.96) between TNC and DM. TNC and DM show similar cyclic patterns caused by plant growth and degree of defoliation. An equation for predicting percent TNC values from percent DM was determined from linear regression analysis.
Relationship of Leaf Elongation to Forage Yield of Tall Fescue Genotype1
Authors: Horst G. L. , Nelson C. J. , Asay K. H.
Published: July 2010

Forage yield is usually not closely related to CO2 exchange rate of single leaves, and existing data suggest other factors such as canopy characters need to be studied. Therefore, we investigated the relationship between leaf elongation rate and forage yield of 14 genotypes of tall fescue (Festuca arundinacea, Schreb.). Plants were grown in the field under summer water stress and with irrigation. Leaf elongation 4, 8, or 16 days after defoliation was related positively to forage yield at the subsequent harvest during the post‐flowering period. Generally correlations with yield were best (r ≥ 0.67 in 11 of 14 sampling periods) for the 16‐day elongation measurement. Significant differences in leaf elongation at 16 days were noted among genotypes for each of the sampling periods for both irrigated and water‐stressed treatments. Differences among genotypes in leaf elongation were not always consistent from date to date indicating some genotype by environment interaction for this character. Range in leaf length and variance attributable to clones were greater under irrigation which suggested that selection would be more efficient with a good growing environment. Broad‐sense heritabilities for leaf elongation at 16 days calculated for data pooled over 2 years were 0.87 and 0.88 for the water‐stressed and irrigated treatment, respectively. Amount of leaf elongation 12 to 16 days after cutting may be a good estimator of subsequent forage yield because it would indicate the degree of radiation interception during early stages of regrowth, and also the rate of achievement of the critical leaf area index. Leaf elongation rate may be an acceptable criterion for estimating regrowth vigor and yield potential of clones and populations in breeding programs.
Analyses of a Dominant Male‐Sterile Character in Upland Cotton. I. Cytological Studies1
Authors: Bowman D. T. , Weaver J. B. , Walker D. B.
Published: July 2010

Cytological observations of microsporogenesis breakdown were used to differentiate a new dominant malesterile character in Upland cotton, Gossypium hirsutum L., from the two known dominant male steriles, Ms4 and Ms7. Unlike the Ms4 genotype where breakdown is either premeiotic or occurs during early stages of meiosis, and unlike the Ms7 genotype where the latest reported breakdown in microsporogenesis occurs at the onset of pollen wall formation, the pollen in the new male sterile aborted only after the entire pollen wall, both intine and exine, had been fully developed. Thus, breakdown was consistently postmeiotic although a few sporogenous cells may first degenerate. Compared to normal fertile pollen grains, the sterile grains had a significantly thicker and more intenscly staining intine. They also possessed plugs at germ‐pore regions that failed to stain with toluidine blue. Histochemistry revealed these plugs were composed of hemicellulose or some complex polysaccharide. Histochemical studies also disclosed a unique layer of insoluble carbohydrate located between the intine and exine walls in the sterile microspores. Cytoplasm disintegrated progressively during pollen development resulting in sterile pollen grains that were conspicuously shriveled and vacuolate at maturity.
Cytoplasmic‐Genotypic Effects in the GT 112 Maize Inbred with Four Cytoplasms1
Authors: Rao A. P. , Fleming A. A.
Published: July 2010

The study of cytoplasmic effects on the expression of agronomic characters is important in learning about cytoplasmic‐nuclear interactions and their influence on breeding and genetic programs. The genotype of the longtime maize (Zea mays L.) inbred, GT 112, was backcrossed six or seven times into three cytoplasms other than its own. Thus, each cytoplasmic source of seed was assumed to have the same nuclear genotype.

The four cytoplasms, studied previously in a double‐cross hybrid, were compared in inbred GT 112 in all possible combinations for 2 years with 10 replications per year. Significant differences among the cytoplasms occurred for germination, number of dead seedlings due to Fusarium sp., diseased plants, plant vigor, color, leaf rolling, date of tasseling and silking, plant and ear heights, yield, and grain quality.

Certain combinations of cytoplasm and inbred genotype gave more desirable performances than others under certain environments. There was a significant or highly significant interaction for year ✕ cytoplasm within pairs for all of the characters tested 2 years except for germination and number of plants before thinning.

Results from these experiments provide further support for cytoplasmic effects on agronomic characters in maize. They also emphasize that the environment can influence the performance of a cytoplasm from one year to another.
Optimal Nutrient Combinations Determined from Isoprobs1
Authors: Geng S. , Williams W. A. , DaVia D. J.
Published: July 2010

Response surface models are frequently used in estimating optimal levels of nutrient inputs. Experimental observations are subject to errors; therefore, results obtained by differentiation of a response surface function do not provide an estimate with due consideration of reproducibility. Walker and Carmer in 1967 related the probability of obtaining an increase in an observed response with an increased input level for a one variable case. We have developed a general procedure to estimate combinations of nutrients that will produce maximal yield based on a specified probability. A contour of combinations of nutrients that have the same probability to produce maximal yield is called an “isoprob”. A unique optimal nutrient‐combination can then be determined from an isoprob under some economic constraints. Data obtained from a greenhouse study of the effects of Ca and P on the yield of ‘Hykon’ rose clover (Trifolium hirtum All.) were used for an illustration. For a given probability level of 0.75, the estimated optimum combination of the two nutrients that depends on their relative costs ranged from 1,296 and 105 ppm to 1,530 and 83 ppm for Ca and P, respectively.
Growth Analysis of Tall Fescue Genotypes Differing in Yield and Leaf Photosynthesis1
Authors: Wilhelm W. W. , Nelson C. J.
Published: July 2010

Relationships between leaf photosynthesis and yield have not been well defined in forage grasses. Therefore, leaf growth, dry matter distribution, carbohydrate concentration, and growth analysis of four genotypes of tall fescue (Festuca arundinacea Schreb.) were examined. Genotypes, selected in the field for high and low CO2 exchange rate (CER) in combination with high and low yield, were compared in an attempt to study the relationship between photosynthesis and yield.

In the vegetative growth stage, high yielding genotypes produced greater amounts of all plant parts (leaves, stem bases, and roots) than did low yielding genotypes; however, low yielding genotypes produced more leaf tissue relative to total increase in plant dry weight than did high yielding genotypes. Water‐soluble carbohydrate (WSC) concentrations of plant parts were significantly different among genotypes, with high‐CER genotypes having highest levels during early stages of regrowth. High yielding genotypes had highest WSC concentrations at later stages regardless of CER rating.

Mean relative growth rates of the four genotypes were similar. Mean net assimilation rates and mean relative leaf area growth rates tended to be greater for the high yielding genotypes than for the low yielding genotypes. Results indicated the greater yields exhibited by the high yielding genotypes regardless of CER rating resulted from (1) greater carbohydrate reserves to initiate new leaf growth, (2) more rapid leaf area development, and (3) partitioning a greater amount of newly assimilated dry matter into leaf tissue during the first 16 to 19 days of regrowth.
Screening Field Peas for Resistance to White Mold1
Authors: Blanchette Bonnie L. , Auld Dick L.
Published: July 2010

Breeding lines and plant introductions were screened in a greenhouse to determine if genetic resistance to white mold (Sclerotiorum sclerotiorum (Lib) de Bary) exists in field pea (Pisum sativum L.). All experiments were conducted in mist chambers maintained at approximately 18 C and 90% relative humidity. Eleven‐day‐old seedlings were inoculated by placing one fungus infested oat kernel next to the base of each stem. Three days after inoculation, disease severity was determined by estimating the length of stem lesions.

Significant differences in disease severity were detected by this visual scoring method. The following plant introductions, breeding lines, and cultivars were more resistant than the susceptible check (‘Garfield’): PI 155109, PI 166188, PI 189171, PI 261622, PI 262189, PI 263027, PI 272191, PI 272205, PI 272209, ID 89‐1, ID 2, Dark Skin Perfection, Perfection 132, and Wisconsin Perfection.
Use of DPX 3778 to Produce Hybrid Wheat Seed1
Authors: Johnson R. R. , Brown C. M.
Published: July 2010

Effective chemical control of pollination would provide an alternative to the cytoplasmic male‐sterile system in hybrid wheat (Triticum aestivum L.) production. The objective of this study was to determine the effect of rate and stage of DPX 3778 [3‐(p‐chlorophenyl)‐6‐methoxy‐ s‐triazine‐2,4‐(1H, 3H) dione‐triethanolamine] applicatlon on the hybridization potential of spring wheat. During 3 years of experimentation, rates of DPX 3778 ranging from 0 to 27 kg/ha were foliarly applied to field.grown plants of ‘Protor’ spring wheat at growth stages ranging from late tillering to late boot. Several treatment rates above 9 kg/ha reduced seed set on bagged spikes to near zero in 2 out of 3 years. Poor pollen control was obtained in a third year and was associated with visible wilting of plants caused by drought prior to and at the time of chemical application. In general, applications during the boot stages or split applications with one‐half of the chemical applied during late boot were most effective in preventing pollen shed. In the first year, good pollen control treatments produced 83 to 98% hybrid seed and resulted in seed yields that ranged from 33 to 80% of non‐treated plants; but in the second year of good pollen control the percent hybrid seeds did not exceed 85% and seed yields were extremly low. Poor hybrid seed production during the second year of good pollen control was associated with high temperature during the cross pollination period. Field and greenhouse studies with 15 winter cultivars indicated that DPX 3778‐induced pollen control was much less effective than in spring wheat.
In Vitro Tissue Culture of Selected Legumes and Plant Regeneration from Callus Cultures of Red Clover1
Authors: Phillips Gregory C. , Collins G. B.
Published: July 2010

A synthetic, chemically defined medium was developed for the initiation and growth of cell and tissue cultures of red clover (Trifolium pratense L.). The medium is broadly supportive and suitable for the culture of other legume species, including alfalfa (Medicago sativa L.), soybeans (Glycine max L.) and jack bean (Canavalia ensiformis L). Cultural variables for red clover were defined, and it is now possible to routinely establish callus cultures of red clover from reproductive and vegetative explant tissues of both mature and immature plants. Cell suspension cultures with rapid cell division rates have been established from calli by adapting the new medium to liquid culture. Organogenesis was induced in callus cultures, and the recovery of whole plants regenerated from callus has been achieved with the cultivars ‘Altaswede’, ‘Arlington’, ‘Kenstar’, ‘Redman’ and ‘Tensas’, but they did not respond equally well. Regenerated plants have been grown to maturity and were fertile. 3‐Aminopyridine was evaluated and found to possess growth‐modifying properties. It is now possible to investigate the use of tissue and cell culture techniques in red clover breeding programs.
Protein Content and Composition of Karl and Related Barleys1
Authors: Burger W. C. , Wesenberg D. M. , Carden J. E. , Pawlisch P. E.
Published: July 2010

The six‐rowed malting barley (Hordeum vulgare L.) cultivar ‘Karl’, which is lower in protein than other malting barleys, was studied to determine how its protein composition differed from that of other six‐rowed barleys. Karl and one of its parents, CI 7147, had significantly lower concentrations of total protein and hordein than ‘Traill’ its other parent, closely related cultivars ‘Good Delta’ and ‘Everest’, and ‘Larker’, a check cultivar. The “Karl‐type” barleys tended to have a greater proportion of salt‐soluble proteins than the other barleys, but glutelin and residual proteins did not differ markedly between the two types.

Lysine concentration of the grain averaged 4.1 g/100 g protein in four Karl‐type barleys and 3.4 in seven non‐Karl type barleys, but lysine concentrations on a sample basis (g amino acid/100 g barley, dry basis) were 0.52 and 0.54, respectively. Under conditions of varied N uptake, hordein was the major repository of protein N in Karl barley. In this respect Karl is similar to other barleys.
Dry Matter Accumulation in Maize Hybrids Near Isogenic for Endosperm Mutants Conditioning Protein Quality1
Authors: Baenziger P. S. , Glover D. V.
Published: July 2010

Six near isogenic genotypes of four maize (Zea mays L.) single‐cross hybrids were grown in a randomized complete block design with a split‐split‐plot arrangement of treatments with four replications. The genotypes were sugary‐2 (su2), waxy (wx) and opaque‐2 (o2), the double mutant combinations [sugary‐2 opaque‐2 (su2 02) and waxy opaque‐2 (wx o2)], and the normal counterpart. The plants in each plot were sib‐pollinated twice by hand to insure full seed sets. Harvests were made at 7‐day intervals beginning 10 days after pollination (DAP) and continuing through 73 DAP. The purpose of this experiment was to determine the effect of the six genotypes on kernel dry matter accumulation (grain weight), cob weight, and grain moisture percentage during the grain filling period.

On the average su2, o2, wx o2, and su2 02 accumulated 13, 18, 20, and 25% less grain weight than normal. The reduction in kernel dry matter accumulation was the result of shorter grain filling periods and less rapid rates of grain filling during the reproductive phase. Waxy accumulated 4% less grain weight than normal. The lower grain weight accumulation of wx was because of a less rapid rate of grain filling and not because of a shorter grain filling period. Opaque‐2 and su2 o2 showed a 9 and 11% reduction of cob weight, respectively, compared to the normal hybrids throughout development. Waxy, wx o2, and su2 hybrids were similar to normal in cob weight accumulations. All of the genotypes retained a higher moisture percent during development than their normal counterpart hybrids. However, on the average, 02 was not significantly different in moisture than normal at 73 DAP.
A Dynamic Model for Plant Growth: Adaptation for Vegetative Growth of Soybeans1
Authors: Wann Mien , Raper C. David
Published: July 2010

A dynamic model for vegetative plant growth has been constructed with a set of nonlinear, ordinary differential equations. The model accepts photosynthetically active radiance (PAR) between 400 and 700 nm wavelengths as input and quantitatively predicts the partitioning of photosynthate to leaves, stems, and roots over a normal range of temperatures. The parameter values for the model which were not measured were estimated with data from an experiment in controlled environment rooms. A determinate cultivar of soybean (Glycine max (L.) Merrill ‘Ransom’) was grown at day/night temperatures of 18/14, 22/18, 26/22, 30/26, and 34/30 C; PAR of 75.0 nE cm‐2sec‐1 during a 9‐hour light period; and CO2 concentration of 400 µliter liter‐1. An interruption in the middle of the dark period by incandescent lamps was used to prevent floral induction. Plants from all treatments were sampled at approximately 2‐day intervals for measurement of total leaf area and dry weights of leaves, stems, and roots.

A comparison of calculated and measured dry weights for soybean plants demonstrated that the model, which previously had been adjusted for simulation of growth for tobacco (Nicotiana tabacum L.), is capable of describing growth of soybeans. Only minor modification of functional forms and parameter values were required for adaptation of the model for simulation of soybeans.
Genetic Variation and Interrelationships of Several Minerals in Orchardgrass Herbage1
Authors: Stratton S. D. , Sleper D. A.
Published: July 2010

Mineral concentrations and their association with grass tetany in grazing animals, have become an important aspect of forage quality, particularly m cool‐season grasses. The objectives of this study were to measure the genetic variation and herltability of P, K, Ca, Mg, the ratio K/(Ca + Mg), and to examine the interrelationships among these minerals in orchardgrass (Dactylis glomerata L.) herbage. Herbage from 14 selected orchardgrass parents and their polycross progenies was analyzed for P, K, Ca, Mg, and the K/(Ca + Mg) ratio at each of three harvest dates in 1976 and 1977. Parental clones differed significantly for all minerals and the cation ratio. There was less variation among the progenies. Years and harvests within years were significantly different. Although heritability values calculated by the parent‐offspring regression and standard unit methods varied, they were of sufficient magnitude to suggest improvement through breeding. Heritability of the K/(Ca + Mg) ratio was low and variable. Correlations of P, K, Ca, Mg, and the cation ratio with yield were generally low in the first harvest. Stability of mineral concentrations and the cation ratio over years was found to be generally acceptable.
Changes in Gene Frequency During Mass, Modified Ear‐To‐Row, and S1 Selection: A Simulation Study1
Authors: Choo T. M. , Kannenberg L. W.
Published: July 2010

Computer simulation studies have indicated that S1 recurrent selection is more efficient than mass or modified ear‐to‐row selection for improving corn (Zea mays L.) populations (Choo and Kannenberg, 1979). The present study extends the comparison of mass, modified ear‐torow, and S1 selection in terms of genetic drift and changes of gene frequency. Severe genetic drift occurred in S1 selection under high (5%) selection intensity. The desirable genes lost during S1 selection included both major (A = 2) and minor (A = 1) genes, with some losses occurring during the very early cycles of selection. Fewer and only minor genes were lost during mass selection. Gene losses under modified ear‐to‐row selection were intermediate. In all cases, genetic drift resulted is losses of alleles of 0.1 initial frequency, with losses being less severe under complete domtnance than under additive gene action. The loss of desirable genes depended almost entirely on their initial frequency and not on the magnitude of their individual effects. The results indicate that if 20 or fewer S1 lines are recombined in each cycle, then another germplasm pool should be maintained as a source of extra genetic variability. S1 selection brought the fastest change of gene frequency regardless of the gene effect and the initial frequency. When gene frequency exceeded 0.5, the rate of increase in gene frequency during S1 selection was similar under the additive and the complete dominance models, but in mass or modified ear‐to‐row selection the rate of increase was much slower under the complete dominance model.
Selection for Chasmogamy in Sericea Lespedeza1
Authors: Donnelly E. D.
Published: July 2010

Lines of sericea lespedeza, Lespedeza cuneata (Dumont) G. Don, genetically high and low in percentage chasmogamous seed (seed from chasmogamous flowers‐PCS) were selected. The F2 from a low ✕ high PCS line produced a high PCS similar to the high parent. Approximately 90% of F2 plants produced chasmogamous seed at a frequency similar to the high parent. More than one dominant gene determines the producnon of chasmogamous flowers and seed, and this trait appears highly heritable if plants are not cut for hay. Cutting once late in the growing season reduced the PCS, particularly of the high PCS lines and of the F1. The low lines were less affected by cutting. To obtain maximum heterosis through increased outcrossing potential, certified seed fields of sericea lespedeza cultivars should not be harvested for hay.
Effect of Crown Rust on Protein and Groat Percentages of Oat Grain1
Authors: Simons M. D. , Youngs V. L. , Booth G. D. , Forsberg R. A.
Published: July 2010

Lines of oats (Arena sativa L.) in breeding nurseries at Madison, Wis. ranged from highly resistant to highly susceptible to infection by crown rust (Puccinia coronata Cda.). The correlation between crown rust severity (as percentage of leaf area affected) and the protein percentage of the grain averaged −0.470 over a 3‐year period. Forty oat lines at Ames, Iowa ranged from moderate to high in susceptibility, as measured by the relative reduction in yield and seed weight caused by crown rust. With extremely high levels of infection, these strains showed significant variation in response of protein and groat percentages to infection. A significant reduction in protein percentage occurred in one strain and significant increases in protein percentages occurred in five other strains. Overall, the effect of crown rust on protein percentage was negatively correlated with its effects on yield (r=−0.362) and seed weight (r=−0.421). The effects crown rust on protein and groat percentages of the different lines, as measured in diseased plots, were not significantly correlated with either the inherent yields or the inherent protein percentages of the lines in unrusted control plots. This suggests that selection in breeding programs for high yield and high protein percentage could be carried out readily in conjunction with selection for crown rust resistance. The heritabilities of the effects of crown rust on protein and groat percentages were 81 and 91%, respectively.
Genetic Variabilty for Resistance to Propanil Injury in Soybeans1
Authors: Karazawa Missae , Caviness C. E.
Published: July 2010

Propanil (3′4′‐dichloropropionanilide) is applied by aircraft to rice [Oryza sativa (L.)] for weed control, therefore, injury from spray drift of this herbicide frequently occurs on plants in nearby soybean [Glycine max (L.) Merr.] fields. Severity of injury from drift has been shown to vary among soybean cultivars. We studied genetic variability for resistance to a drift rate in crosses between resistant ✕ resistant, susceptible ✕ resistant, and susceptible ✕ susceptible parents. Mean scores for F1 populations from crosses between susceptible ✕ resistant parents indicated partial dominance for resistance to propanil injury. It was not possible from the data to determine the actual number of genes responsible for this trait, but F2 distributions indicated a relatively small number was involved. Broad sense heritability estimates ranged from 38 to 50% in crosses involving susceptible ✕ resistant parents to near zero for crosses between susceptible ✕ susceptible and resistant ✕ resistant parents.
Gene Arrangement in the Duplicate Linkage Groups V and IX: Nectariless, Glandless, and Withering Bract in Cotton1
Authors: Kohel R. J.
Published: July 2010

Genetic investigations of Upland cotton, Gossypium hirsutum L., have established that the genes controlling the expression of nectariless (ne1, ne2), glandless (gl2, gl3), and withering bract (bw1, bw2) are at duplicate loci in homeologous chromosomes. Three‐point linkage tests in these homeologous linkage groups indicate that the gene order was probably Gl2‐Bw1‐Ne1 in the A genome and Bw2‐Gl3‐Ne2 in the D genome. However, recombination percentages were not significantly different between Bw1‐Ne1 and Gl2‐Ne1 in the A genome, and between Bw2‐Ne2 in the D genome.
Combining Ability in Cotton for Resistance to Pink Bollworm1
Authors: Wilson F. D. , George B. W.
Published: July 2010

Seed damage by pink bollworm (PBW) (Pectinophora gossypiella Saunders), to cotton (Gossypium hirsutum L.) grown for 2 years at Tempe, Ariz. in insecticide‐f~ee environments was determined in six parents and in all of their hybrid and reciprocal combinations. The six parents included two cultivars, ‘Deltapine 61’ and ‘Stoneville 256’, three primitive race stocks, Texas 31 (T‐31), 55, and T‐167, and an upland breeding stock of complex parentage, designated AET‐5. The latter four p~rents had been selected for PBW resistance in earlier tests. Parents and hybrids grown in 1977 showed significant genetic variability only at the fourth of five harvest dates, whereas those grown in 1978 showed significant variability at all four hgrvest dates. For both years, at the only directly comparable harvest, general combining ability estimates (GCA) were significant for low seed damage in T‐167 and AET‐5 and significant for high seed damage in T‐55. Significant effects from specific combining ability (SCA) were shown for six of the hybrid combinations for at least one harvest date. The combinations of most interest, cultivar ✕ T‐167, cultivar ✕ AET‐5, and T‐167 ✕ AET‐5, showed only GCA effects. Maternal effects were not significant. Significant reciprocal effects at two harvest dates were confined to two hybrid combinations. On the basis of GCA estimates, T‐167 and AET‐5 should each combine well for low seed damage.
Comparison Between Kjeldahl and Near Infrared Protein Analyses on Vegetative and Head Samples of Wheat1
Authors: Klepper Lowell , Wilhelmi Kenneth
Published: July 2010

A Technicon Dickey‐john Near Infrared (NIR) Analyzer (lnfra Alyzer) was used to determine if NIR analyses could be used to study protein translocation in wheat (Triticum aestivum L.). It was calibrated, using Kjeldahl protein values, for wheat head and vegetative protein. These calibrations were tested with samples from a field experiment involving different cultivars, different levels of N application, and time of application. Correlation coefficients (r) were calculated between Kjeldahl and NIR protein from head emergence to maturity. For wheat head protein, the overall r = +0.82 and for wheat vegetative protein, r =‐ +0.97. It was concluded that NIR analyses were sufficiently accurate to be utilized in wheat protein translocation studies.
Growth, Development, and Cold Tolerence of Fall‐acclimated Cereal Grains1
Authors: Fowler D. B. , Carles R. J.
Published: July 2010

Areas of adaptation of winter cereals are determined primarily by each species' ability to tolerate cold. These differences in cold hardiness were investigated during fall acclimation of spring and winter cultivars of rye (Secale cereale L.), wheat (Triticum aestivum L.), barley (Hwrdeum vulgwre L.), and oats (Avena sativa L). Material for these studies was acclimated under field conditions in the fall of 1972, 1975 and/or 1977 at Saskatoon, Sask., Canada.

Spring cultivars ocasionally demonstrated a limited ability to acclimate to cold. The maximum cold hardiness attained by the hardiest cultivar of each species when fully acclimated was −13, −15, −21, and −30 C for. oats, barley, wheat, and rye, respectively.

During acclimation, crown and shoot dry weight increased and days to head and percent crown water decreased for most of the cultivars considered. In both spring and winter cultivars, dry matter accumulated at a rate which would suggest that energy production during the acclimation period was not a limiting factor for cold acclimation under normal fall field conditions. Percent crown water was closely associated with cold hardiness for comparisons within species. However, there were differences in the responses among species indicating that acclimation to cold was more complex than simply the regulation of tissue water content.
Interspecific Hybrids Between Helianthus maximiliani Schrad. and H. annuus L.: Effect of Backcrossing on Meiosis, Anther Morphology, and Seed Characteristics1
Authors: Whelan Ernest D. P. , Dorrell D. G.
Published: July 2010

Substitutions of the nucleus of Helianthus annuus L. (2n = 34; x = 17) into the cytoplasm of the perennial H. maximiliani Schrad. (2n = 34) were obtained by hybridizing H. maximiliani with wild H. annuus, and then backcrossing, using cultivated H. annuus ‘Saturn’ as the recurrent pollen parent. A paracentric inversion, evident in the F1, was eliminated by one cross with ‘Saturn’, and multivalents were rare after the first backcross. Pollen fertility improved with backcrossing. Trisomic plants occurred in all three progenies investigated, but with differing frequencies. Oil content and 1,000‐seed weight increased with backcrossing. Seed weight of trisomic plants was significantly greater than that of diploid sibs; oil content also tended to be higher. Backcrossing also affected anther morphology. Some plants had highly modified and almost vestigial anthers, which contained little or no pollen, but all trisomic plants had normal anthers. If selection for male‐sterility, probably cytoplasmic, is desired, trisomics should be avoided when backcrossing.
Sucrose Concentration Gradients in Wheat Leaves1
Authors: Lee H. J. , Ashley D. A. , Brown R. H.
Published: July 2010

The movement of sucrose from leaves of crop plants may be limited by diffusion from photosynthetic sites to the veins, and this diffusional transport may, in turn, limit photosynthesis and growth. If sucrose moves to veins by diffusion, concentration gradients must be established that favor diffusion. Experiments were conducted with wheat leaves to assay sucrose concentrations in tissue cross‐sections using cryostatic techniques. Fresh‐frozen leaf sections, 30 µm thick, were cut serially between veins and assayed for sucrose. Plastic embedded leaf tissue was sectioned in an ultramicrotome for anatomical study of tissue analogous to that assayed for sucrose. Air space was estimated to comprise about 9% of the tissue crosssection in the vein region, 23% midway between veins, and 38% of the mesophyll adjacent to the vein. The volume of tissue, minus air space, and tissue dry weight were nearly constant between veins. The absolute amount of sucrose per 30 µm section was higher in the vein than in the interveinal regions. Since vein sections were nearly twice as heavy as interveinal sections, sucrose per unit of dry weight was higher in the interveinal regions, except for leaves with no light pretreatment. There was also a tendency for sucrose expressed on a molar basis to be higher in the interveinal regions. Sucrose concentration increased in the mesophyll from the region nearest the veins to the mid‐interveinal region, especially after onehalf and three hours in the light. Sucrose concentrations increased for the first 3 hours in the light, but there was little further increase up to 24 hours. Using a sucrose concentration gradient in the mesophyll of 2.03 M cm‐1 after 3 hours of light, a potential sucrose flux rate of 3,533 p mole cm‐2 sec‐1 was calculated. This rate assumes the whole leaf cross‐section, minus air space, serves as a pathway of sucrose movement. A flux rate calculated from an assumed apparent photosynthesis of 1.26 n mole CO2 cm‐2sec‐1 (20 mg dm‐2hour‐1) and the accumulation of sucrose in 3 hours of light is 14.16 p mole cm‐2sec‐1 suggesting that the pathway for sucrose transport is only about 0.4% of the leaf cross‐section.
A Low‐Cost System For Circulating Nutrient Solutions In Pot Studies1
Authors: Guevarra A. B. , Kitamura Y. , Whitney A. S. , Cassman K. G.
Published: July 2010

A simple, inexpensive nutrient solution circulation system was developed which could be duplicated in developing countries. The airlift perfusion principle was employed to continuously recirculate nutrient solution within individual pots containing porous medium. The system has proven to be very satisfactory for N studies including an 15N experiment and an evaluation of the transfer of legume‐fixed N to a grass growing in a separate pot.
Aluminum Tolerance of Spring Rye Inbred Lines1
Authors: Aniol Andrzej , Hill R. D. , Larter E. N.
Published: July 2010

Three hundred seventeen spring rye (Secale cereale L.) inbred lines, 15 cultivars of wheat (Triticum aestivum L.), and three lines of triticale (✕ trlticosecale Wittmack) were tested for Al tolerance. The seedlings were grown in solution‐paper medium and the roots were exposed for 48 hours to Al at different concentrations. The ability of roots to regrow after Al treatment was assessed. Approximately 75% of the rye lines tested showed root regrowth after exposure to Al concentrations of at least 30 ppm. The irreversible inhibition of root growth at a particular level of Al concentration in nutrient solution was associated with a significant increase in Al concentration in roots. The more tolerant rye lines were able to tolerate a significantly higher concentration of Al in their roots than those less tolerant. Variability in the reaction to Al was found within some inbred rye lines even though thye were S5 to S8 inbreds. No rye lines showed a greater tolerance to Al than the most tolerant wheat cultivars. Alumininm concentration in roots of tolerant wheat cultivars was lower than in rye lines. Two of the three triticale lines tested were highly tolerant to Al. The screening method is suitable for selecting homozygous tolerant lines.
Recurrent Selection for Improved Rate of Germination in Annual Ryegrass1
Authors: Nelson L. R.
Published: July 2010

Rapid germination of annual ryegrass (Lolium multiflorum Lam.) is desirable for stand establishment and early grazing. The primary objective of this study was to improve germination rate of ryegrass by using recurrent selection from a widely diverse bulk population. We were also interested in determining whether rate of germination in ryegrass is a heritable trait that can be manipulated by breeding efforts. No progress was made for increased rate of germination in two cycles of recurrent selection. Selection for delayed germination was successful and heritability values for that variable were quite high.
Changes in Photosynthesis, Ribulose Bisphosphate Carboxylase, Proteolytic Activity, and Ultrastructure of Soybean Leaves during Senescence1
Authors: Wittenbach V. A. , Ackerson R. C. , Giaquinta R. T. , Hebert R. R.
Published: July 2010

Changes in photosynthesis, rlbulose bisphosphate carboxylase (RuBPCase), and proteolytic activity were followed in the leaves of field‐grown soybeans [Glycine max (L.) Merr. cv. Kent] from flowering through senescence. These parameters were followed in relation to changes in leaf resistance, chlorophyll, protein, starch, total N levels, and seed development. In addition, changes in leaf ultrastructure were observed. The initial symptoms of senescence (evident 3 to 4 weeks after flowering) were a decline in photosynthesis, chlorophyll, and total leaf N and an increase in proteolytic activity. Preceding these changes there was a swelling of the chloroplasts and a disorientation of the chloroplast lamellae, possibly resulting from the apparent increase in starch deposition. Also, large numbers of osmiophilic granules appeared within the chloroplasts. These changes were evident prior to the time the seed entered its most rapid period of growth which was 4 to 7 weeks after flowering, The initial decline in photosynthesis did not appear to be due to an increase in leaf resistance or a decline in RuBPCase activity or level. The decline in protein levels began between 5 and 6 weeks after flowering and was paralleled by the decline in carboxylase activity and level. Associated with these changes were an increase in the size of the osmiophilic granules within the chloroplasts, a decrease in the number of chloroplasts with a corresponding increase in the apparent cellular breakdown products, and a dissolution of the vacuoles. No large increase in leaf resistance or change in specific activity of carboxylase was observed until late in senescence.
Improving Corn Population for Grain Yield and Resistance to Leaf Blight and Stalk Rot1
Authors: Miles J. W. , Dudley J. W. , White D. G. , Lambert R. J.
Published: July 2010

Estimates of among and within half‐sib family varl. ance components for disease scores in each of two corn (Zea mays L.) populations were obtained from artificially inoculated experiments in 1, 2, or 3 years. These estimates were used to predict response to mass, half‐sib, and S1 selection for resistance to northern corn leaf blight (caused by Helminthosporium turcicum Pass.), Diplodia stalk rot [caused by Diplodia maydis (Berk.) Sacc.], and anthracnose leaf blight and stalk rot [caused by Colletotrichum graminicola (Ces.) Wils.]. In addition, among half‐sib family variance component estimates for yield were obtained from unlnoculated experiments for the same families. Genetic correlations among yield and reactions to the four diseases were estimated.

Per‐year predicted gains in ieaf blight resistance for mass selection with pollen control were greater than for either S1 or half‐sib family selection (with 20 plants per family). Per‐year predicted gain for mass selection‐for stalk rot resistance was greater than that for half‐sib family selection (20 plants per family), For a given selection intensity and effective population size, predicted gain in stalk rot resistance for mass selection with pollen control is about equal to that for S1 selection at a great reduction in the number of plants rated for disease reaction and at no increase in the required number of hand pollinations.

Genetic correlations between grain yield in the absence of disease and disease reactions were all near zero and nonsignificant. All significant genetic correlations among disease reactions were positive. These results suggest that mass selection would be the most efficient method of improving disease resistance in corn populations and that such improvement would not affect yield potential of the populations if adequate effective population size is maintained.
Significance of Incompatibility Reactions of Rhizobium japonicum Strains with Soybean Host Genotypes1
Authors: Devine T. E. , Breithaupt B. H.
Published: July 2010

A sample of soybean [Glycine max (L.) Merr.] plant introductions from Asia, representing maturity groups 00 through X, was tested for the presence of the Rj2 and Rj4 genes. Both of these genes condition ineffective nodulation responses: Rj2, specifically with the cl and 122 serogroups of Rhizobium japonicum; Rj4, with R. japonicum strain 61. Rj2 was present in 19 of the 851 fines tested. The 19 lines were in maturity groups III to VIII and most originated from China and Japan. Rj4 was present in 261 of the 851 lines tested, and was most prevalent in lines from southeast Asia. This gene occurred in lines from maturity groups 00 to X and was most frequent in Group X with 94% of the lines possessing it. This evidence of geographical differences in gene frequencies suggests that the combinations of host and Rhizobium ecotypes which coevolved in Asia may have been disrupted through separate introduction of the host and microsymbiont to the New World. If this is the case, N2 fixation may be improved by reassembling the host/strain combinations that evolved in Asia. Use of incompatibility responses may enable soybean breeders to control host specification of symbiosis with genetically improved Rhizobium strains. Host compatibility with indigeneous Rhizobium strains may profoundly affect performance of some plant introductions in evaluation nurseries on soils of low N fertility. Management of N fertility in such nurseries will depend on breeders' objectives.
Alteration of the Internal Water Relations of Rice in Response to Drought Hardening1
Authors: Cutler J. M. , Shahan K. W. , Steponkus P. L.
Published: July 2010

Alterations of the internal water relations due to ex. posure to conditioning drought stress were investigated in the leaves of 4 upland rice cultivars. Plants exposed to such conditioning exhibited alterations indicative of osmotic adjustment. Solute potentials of leaves of conditioned plants were 3 to 5 bars more negative than those of control plants at similar water potential or relative water content. As a result, maximal bulk turgor potentials were greater and turgot was maintained to more negative leaf water potential in conditioned plants. Concurrent analysis of the bulk volumetric modulus of elasticity indicated that tissue mechanical properties were not altered by conditioning. All cultivars examined were found to adjust osmotically and the extent of adjustment was similar for all.
Day‐degree Units and Time in Relation to Vegetative Development and Fruiting for Three Cultivars of Cotton1
Authors: Young E. F. , Taylor R. M. , Petersen H. D.
Published: July 2010

In a test of two Upland cotton (Gossypium hlrsutum L.) cultivars and one Pima (G. barbadmme L.) cultivar Planted on five dates, fewer days were required to produce first true leaf, square, and flower stages as the date of planting was advanced from 1 April to 27 May. Days from planting required to produce open bolls decreased as planting temperatures approached an optimum, then increased for the last planting date. Differences among planting dates for cumulative day‐degree units needed to produce flowers and true leaves were non‐significant, whereas those needed to produce the square and open boll stages were significant. The boll period increased with delay of the flower and harvest stages as the season progressed. The numbers of day‐degree units and heat units were negatively correlated with the length of the boll period. The number of day‐degree units gave a better estimate of boll period by harvest week than the number of heat units. Boll period was influenced more by reductions in day‐degree units in ‘Pima S‐4’ than in the two Upland cultivars.
Facultative Apomixis in Buffelgrass1
Authors: Sherwood R. T. , Young B. A. , Bashaw E. C.
Published: July 2010

We studied embryo sac morphology, chromosome number, reproductive behavior, and phenotype of buffelgrass (Cenchrus ciliaris L.) line 18‐35 to obtain further evidence regarding the occurrence of facultative apomixis in the species. Line 18‐35 is an F1 llne derived from a cross of obligately sexual TAM‐CRD B‐Is with an apomictic plant from Africa. Within line 18‐35, pistils with single sexual embryo sacs of the Polygonum type occurred at a low frequency in the same inflorescences as pistils with aposporous apomictic embryo sacs of the Oenothera type. Some pistils contained a sexual sac and one or more aposporous sacs. A sample of 2,057 pistils from three field plantings and one greenhouse planting had 85.8% apomictic pistils, 5.8% sexual pistils, and 8.4% mixed pistils. Frequency of sexual pistils differed between sampling dates of one field, indicating that environment may have influenced embryo sac type.

In a spaced planting of 1,292 open‐pollinated progeny of 18‐35, 1,252 progeny resembled the maternal parent, and 40 progeny were offtype. Line 18‐35 and 21 of the offtype progeny were tetraploid (2n = 36). Four of these offtype tetraplold progeny produced primarily or exclusively sexual pistils. The 21 offtype tetraplold progeny probably originated by fertilization of reduced eggs. Fifteen offtype progeny were hexaploid and were believed to originate by fertilization of unreduced eggs. We concluded that line 18‐35 is facultatively apomictic.