bluuebunny/crossref_metadata_2025 huggingface dataset:
Anther Lewngth in Wheat: Optimum Sample Size1
Authors: Atashi‐Rang G. , Lucken K. A.
Published: July 2010

Sampling procedures for determining anther length in wheat (Triticum aestivum L. em Thell.) were evaluated using variance components to calculate the relative efficiency of different anther sampling combinations of anthers/ floret, florets/spikelet, spikelets/spike, spikes/replication, and number of replications for two cultivars.

Anther length is a useful indicator of anther size and is correlated with pollen grains per anther, a possible index of pollen available for cross‐pollination in hybrid wheat seed production.

Variation for anther length among anthers within florets, florets within spikelets, and spikelets within spikes was small relative to variation among spikes and replications. Relative efficiency calculations indicated that a cultivar's anther length could be determined satisfactorily by measuring as few as one to three anthers/spike —with sufficient replication and sampling of spikes/plot. The relationship between relative efficiency and number of spikes sampled/plot was curvilinear; relative efficiency was improved only slightly by sampling more than 10 spikes/plot. Relative efficiency increased linearily with each additional replication for all sampling combinations.
Growth and Maintenance Requirements of White Clover as a Function of Daylength1
Authors: McCree K. J. , Kresovich S.
Published: July 2010

Carbon dioxide exchange rates of white clover (Trifolium repens L.) stands were monitored for several days at 30 C, a high light level (2.0 mE.s−1.m−2), and different day/night lengths in the range 6/18 to 18/6 hours. The plants were then kept in continuous darkness for 2 days. Thornley's growth and maintenance coefficients were calculated from the 24 hour CO2 exchange rates. The yield of new biomass carbon (C) per unit of C input into growth (Yg) was found to be independent of daylength, the average value being 0.74 ± 0.01. The maintenance loss rate of C per unit of biomass C present (m), increased from 36 to 53 mg.g−1 24hour−1 as the daylength increased from 6 to 18 hours. This was shown to be an indirect effect of the seven‐fold increase in the growth rate (24 hour net gain) from 12 to 90 g Co2.m−3.24hour−1. No direct effect of daylength on either growth or maintenance requirements was found.
Increased Female Fertility Associated with the ms1 Locus in Soybeans1
Authors: Boerma H. R. , Cooper R. L.
Published: July 2010

Segregation for male sterility was observed in an F3 line of the soybean, Glycine max (L.) Merr., cross L67‐533 ✕ ‘SRF 300’ and designated as the Urbana Male Sterile (UMS). Segregation in this line and between‐ and within family segregation the following generation indicated UMS was controlled by a single recessive gene pair. Crosses made with the North Carolina Male Sterile (NCMS), ms1ms2, suggested that UMS and NCMS were controlled by the same gene or a different allele at the same locus. Male‐sterile plants of UMS had higher levels of female fertility than did male‐sterile plants of NCMS in various genetic backgrounds and in two diverse environments. The increased female fertility of the UMS male‐sterile plants was expressed as a higher frequency of plants with at least one 3‐seeded pod and a lower frequency of plants with no seed.
Genetic Variability for Yield and Plant Height in Crownvetch1
Authors: Baluch S. J. , Risius M. L. , Hill R. R. , Cleveland R. W.
Published: July 2010

Fifty randomly selected crownvetch plants (Coronilla varia L. ‘Chemung’) were mated in a nested sib‐mating design, and the parents and their progenies were analyzed to obtain information on the nature of genetic variability of forage yield and plant height. Forage yield at each of two harvests per season, total forage yield, and plant height at each harvest time were evaluated in each of two growing seasons.

Significant variability among the parents and crosses indicated that genetic variance was present for each character. Most of the genetic variance was additive for each character studied. Heritability estimates (in decimal fraction) for yield ranged from 0.05 to 0.28 while those for plant height ranged from 0.10 to 0.22. Mass or individual plant selection should be effective in changing plant height, but family or progeny test selection should be practiced for yield in crownvetch.
Physiology of Oil Seeds. VII. Growing Season and Location Effects on Seedling Vigor and Ethylene Production by Seeds of Three Peanut Cultivars1,2
Authors: Ketring D. L. , Simpson C. E. , Smith O. D.
Published: July 2010

Seeds of three peanut (Arachis hypogaea L.) cultivars from two growing seasons, 1974 and 1975, and four locations in Texas were tested for germinability and ethylene production. Because ethylene is an important regulator of peanut seed germination, we attempted to correlate its production with differences in early seedling growth. We found three growth distributions and ethylene production patterns. 1) When the majority of the seeds in the population had a high degree of vigor (78±8% of the seedlings had a hypocotyl‐radicle length >20 mm at 70 hours of germination), they also had a characteristic ethylene production maximum at 21 hours of germination. 2) When the majority of the seeds in the population had a low degree of vigor (only 30% of the seedlings had a hypocotyl‐radicle length >20 ram), ethylene production was reduced at 21 hours and the maximum occurred at 45 hours of germination. 3) When a majority of the seeds were in intermediate growth between 1) and 2), ethylene production was reduced by about 50% at 21 hours for the high ethylene‐producing cultivars ‘Starr’ and ‘Tamnut 74’, but was not significantly changed for ‘Florunner’, a comparatively low ethylene‐producing cultivar. Reduced seedling vigor was significantly correlated with decreased ethylene production at 21 hours for Start and Tamnut 74, but not for Florunner. Both seedling growth and ethylene production were altered by growing season and location. The majority of the seeds in the population, however, showed vigorous growth when the ethylene production rates exceeded a critical minimum level.
Effects of a Phosphate Defoliant on Cotton Leaves: Water Relations and Free Amino Acids1
Authors: Elmore C. D. , McMichael B. L. , Cathey G. W.
Published: July 2010

The phosphate defoliant DEF (S,S,S‐Tributylphosphorothrithioate) was sprayed on presquaring greenhousegrown cotton (Gossypium hirsutum L.) plants. Plant water status and leaf area data were taken at 3‐hour intervals during the 1st day and daily thereafter. Stomatal diffusion resistance was measured during the 1st day only. Leaves were analyzed for total N, soluble N, and distribution of free amino acids. Little change in any of the parameters measured was noted the 1st day. On subsequent days the DEF‐treated leaves had lower leaf water potential recovery values (predawn measurement) and lower specific weights (fresh weight basis). DEFtreated leaves, however, had a higher specific leaf weight on a dry weight basis. Leaf N percent did not change as a result of the DEF treatment. Soluble N increased up to twice that of the controls by the 3rd day. The distribution of free amino acids in DEF treated leaves was altered. The concentrations of all amino acids except aspartic acid, glutamic acid + glutamine, proline and valine were significantly increased in the DEF treated leaves. The exceptions remained stable or tended to decrease. The results indicated that DEF‐treated leaves may be mobilizing the leaf protein prior to abscission, but that transport out of the leaf is impeded. Further experiments are needed to substantiate this notion.
Inheritance of an Induced Mutation for Bacterial Blight Resistance in Cotton1
Authors: Brinkerhoff L. A. , Verhalen Laval M. , Mamaghani Reza , Johnson William M.
Published: July 2010

An induced mutation for an intermediate level of resistance to bacterial blight [Xanthomonas malvacearum (E. F. Sm.) Dows.] in cotton (Gossypium hirsutum L.) was obtained after irradiating seed of a blight‐susceptible cultivar, ‘Westburn 70’, with fission neutrons. Inheritance studies indicated that the resistance was due to a single dominant gene. The mutant was not identical to B3, B4, B5, B7, or BN. Tests of homology with 12 other known bacterial blight resistance genes have not yet been conducted.
Relative Responses of Four Flax‐Rust Differential Lines to FeEDDHA1
Authors: Moraghan J. T. , Ralowicz P.
Published: July 2010

Flax (Linum usitatissimum L.) accumulates Mn and develops Mn toxicity symptoms when grown on certain soils low in available Fe. Application of FeEDDHA decreases Mn accumulation and eliminates Mn toxicity symptoms in such cases. This greenhouse study compares the susceptibility of four closely related flax lines (Differentials 1, 3, 16, and 17) used in rust (Melampsora lini) studies, to Mn toxicity and the response to soil‐applied FeEDDHA. Differential 3 showed the most response to the added chelate. A preplant soil application of 2 ppm FeEDDHA‐Fe eliminated the lower leaf scorch presumably associated with Mn toxicity, increased total dry matter yield and Fe accumulation, and decreased Mn accumulation in above‐ground parts of all four lines. However, dry matter yield of Differential 3 was increased 81% after 64 days as compared to 27, 18, and 33% for Differentials 1, 16, and 17, respectively. Genotype, either in the presence or absence of FeEDDHA, had little effect on Mn and Fe concentration, indicating factors besides uptake and concentration of these ions are responsible for the poor growth of Differential 3 in certain soils low in available Fe. Phosphorus and Zn concentrations were not apparently related to the greater susceptibility of Differential 3 to Mn toxicity.
Genotypic Differences for Reduction in Carbon Exchange Rates as Associated with Assimilate Accumulation in Soybean Leaves1
Authors: Hanson W. D. , Yeh R. Y.
Published: July 2010

Six soybean [Glycine max (L.) Merrill] genotypes which differed in growth characteristics were selected to test the hypothesis that genotypes differed in their capacity to maintain carbon exchange rates (CER) at original levels as assimilate accumulated. Chilling (4 C) a 3 cm section of the leaf petiole for 3 hours created a 5.3‐fold increase for sucrose and 1.4‐fold increase for starch in the leaf relative to the control leaves with nonchilled petioles. Levels of sucrose and starch continued to increase with an additional 4 hours of chilling the petiole. Sucrose and starch levels increased in the leaf blade primarily as compared with the petiole and leaf veins. Transpiration rates and stomatal diffusive resistances were similar for chilled and nonchilled petiole treatments. All genotypes had similar decreases in stomatal diffusive resistances during 3 hours of chilled petiole treatment. Differences in reduction of carbon exchange rates (CER) were found among genotypes when petioles were chilled for 3 hours. Those genotypes whose CER were unaltered by chilling did not accumulate more sucrose and starch in the leaves than genotypes whose CER declined. In a 7‐hour chilled petiole study, the change in CER was inversely proportional to level of sucrose in the leaf blade. Genotypic differences for maintaining CER with assimilate accumulation in the leaf were not found.
Relation of Morphological Characters and Shoot Yield in Wheat1
Authors: Ledent J. F. , Moss Dale M.
Published: July 2010

Measurements were made on morphological components of the wheat (Triticum aestivum L. em Thell) shoot. The relationship of a morphological component and grain yield per shoot was determined for four winter wheat cultivars in Belgium and two sprisg wheat cultivars in Minnesota in various field planting patterns and in various controlled environments. The shoot was the measurement unit in these studies. Measurements of 37 morphological traits including such traits as shoot grain yield; kernel number; lengths, widths and dry weights of leaves, sheaths, and stem segments; dry weights of awns and spikes; flag leaf angle; and heights of insertion of leaves and spikes. The data were analyzed by calculating simple correlation coefficients and by using stepwise regression and factor analyses. All three methods indicated that the characters most closely related to grain yield per shoot were kernel number, awn dry weight, some sheath and stem dry weights, and leaf dry weights, in that order. The number of spikelets ranked between awn dry weight and the stem dry weights in the closeness ot their relationship with yield. Leaf length and width characters, height of insertion of plant organs, and leaf angle were all poorly yanked in comparison to other morphological traits in closeness of association with grain yield per shoot.
A Diversity Analysis of a World Collection of Barley1
Authors: Tolbert D. M. , Qualset C. O. , Jain S. K. , Craddock J. C.
Published: July 2010

Data on more than 17,000 accessions of the barley (Hordeum vulgare L.) world collection maintained by the USDA, SEA, were analyzed for variation of five morphological characters (growth habit, caryopsis type, awn type, kernel row number, and kernel color). Phenotypic frequencies within the accessions from each of 48 countries, grouped in 14 regions, were tabulated. Polymorphism was widespread in most countries for different sets of characters. Very weak east‐west clinal patterns were observed and this analysis only partially supported the earlier reported patterns of variation in the postulated centers of diversity. This result may be due to an inadequate sample of characters available for analysis and/or an inadequate number of geographic regions in the world collection.

The H' diversity index was computed for each country and region, for individual characters, and after pooling all five characters. Analyses indicated the between‐regions component of diversity to be relatively smaller than the variation in H' among characters and among countries within regions. This analysis shows no distinct geographical patterns in these data, but its use with additional data is warranted.
Physiological Comparisons of Isogenic Diploid‐Tetraploid, Tetraploid‐Octoploid Alfalfa Populations1
Authors: Pfeiffer Todd , Schrader L. E. , Bingham E. T.
Published: July 2010

Two isogenic paired sets of alfalfa (Medicago sativa L.), a diploid (2n = 2x = 16) and tetraploid (2n = 32) set plus a tetraploid and octoploid (2n = 8x = 64) set, were compared in two growth chamber experiments for photosynthesis, N fixation, and dry matter accumulation on a whole‐plant basis. In Experiment A, each plant was harvested when it had open flowers on two racemes. Plants were harvested on a weekly basis in Experiment B.

Within each set, the higher ploidy level reached the harvest stage approximately 9 days earlier. This maturity differential affected the comparisons of dry matter accumulation in Experiment A. Fresh and dry weights of leaves, stems, and roots did not differ in Experiment A. In Experiment B, the 4x had significantly greater herbage fresh weight than the 2x, while the 4x and 8x pair did not differ significantly. Net CO2 exchange (NCE) on a whole‐plant basis was equivalent across ploidy levels in both experiments. Acetylene reduction on both a whole‐plant and nodule‐weight basis and nodule number and nodule weight did not differ significantly at the different ploidy levels in either experiment. For measurements taken only during Experiment A, NCE was greater in the 4x compared to the 8x on a chlorophyll basis; transpiration was significantly greater in the 8x than in the 4x, and the chlorophyll a:b ratio was lower in the 8x than the 4x. Root respiration did not differ. When nonhomogeneous variances between ploidy levels were compared, in 17 out of 18 comparisons the lower ploidy level had the greater variance.

The ploidy level had little effect on physiological processes in the isogenic populations of this study. Because greater variance exists with lower ploidy levels, selection should be more easily performed at lower ploidy levels.
Individual Crown Selection for Resistance to Freezing Stress in Winter Oats1
Authors: Marshall H. G. , Kolb F. L.
Published: July 2010

In recent years, crown freezing tests have been used to classify germplasm of small grain crops for resistance to freezing stress, a major component of winter hardiness. Selection has been based, however, on large numbers of crowns, and techniques for individual plant selection have not been developed. Our objective was to develop a system for growing and hardening winter oats (Avena byzantina K. Koch and A. saliva L.) that will provide uniform expression of the freezing resistance trait and facilitate accurate individual crown selection.

A technique of growing plants in individual tubes under controlled conditions of light, temperature, and moisture was developed. Individual crowns were frozen in capped vials on rotating shelves in a freezing chamber. Crowns that survived severe freezing stress and regenerated new roots were saved as selections.

Effectiveness of the technique was tested by applying two cycles of crown selection to a four cultivar blend. After cycles 1 and 2, the mean injury scores of the population were 95.6 and 100%, respectively, of the most hardy component cultivar. In a second experiment, crowns of an F6 bulk population were frozen and only 16 out of 640 survived. In subsequent tests of these lines, nine were equal to the hardy parent and 13 were equal or superior to the population mean. Thus, our crown selection technique provided a degree of precision that should be useful in breeding for increased resistance to freezing stress and improved winter hardiness.
Cytogenetic and Taxonomic Relationships among Three Diploid Crested Wheatgrasses1
Authors: Dewey D. R. , Asay K. H.
Published: July 2010

Until recently, only one diploid (2n= 14) taxon of crested wheatgrass [Agropyron cristatum (L.) Gaertn.] was recognized. This diploid, ‘Fairway’, differs morphologically from two diploid plant introductions, PI 229574 from Iran and PI 314600 from the USSR. The purposes of this study were to: (1) define the genomic relationships among the three diploid taxa, (2) determine if restrictions to gene flow occur among the diploids, and (3) examine the taxonomic implications of the data.

The diploid taxa were hybridized with relative ease and produced F1 hybrids that were morphologically intermediate to their parents. Mean chromosome pairing at Metaphase I in the three hybrid combinations ranged from 1.38 to 2.25I, 5.05 to 5.83II, 0.03 to 0.52III, and 0.005 to 0.18IV. The pairing data demonstrate that the diploids contain the same basic genome, but their genomes differ by structural rearrangements of some chromosomes. Stainable pollen averaged 19.3 to 24.6% and seed set averaged 0.25 to 0.58 seeds per spike in the three hybrid combinations. The moderately high sterility in the hybrids serves as a genetic barrier but does not preclude gene flow among the diploids.

The three diploid taxa are correctly identified as A. cristatum, but they should be separated at the subspecies level. We think that PI 229574 belongs to A. cristatum subsp. cristatum. However, subspecies designations for Fairway and PI 314600 must be deferred until more information is accumulated.
Gas Exchange and Leaf Area Characteristics of Four Tall Fescue Selections Differing in Forage Yield1
Authors: Cohen C. J. , Chilcote D. O. , Frakes R. V.
Published: July 2010

Gas exchange and leaf area characteristics of four tall fescue (Festuca arundinacea Schreb.) selections differing in forage yield were examined under greenhouse and laboratory conditions to determine if these characteristics might be related to yield differences. Carbon dioxide exchange rates (CER) and specific leaf weight of leaf blades of ten genotypes per selection were measured in December 1978 and April 1979. In April 1979, dark respiration and transpiration rates of leaf blades were also evaluated. Leaf elongation rate, leaf width, and leaf area expansion rate were assessed during three measurement periods.

In December 1978, the lowest‐yielding selection, TFM 16, had 20% greater CER than the high‐yield selections, TFM 26 and TFK 4, and 8% greater CER than TFK 12. Differences in CER were not statistically significant in April. No significant differences among selections for transpiration, dark respiration, or specific leaf weight were found.

High yielding TFM 26 had significantly greater leaf elongation and leaf area expansion rates in one measurement period (by 28 to 48% and 24 to 43%, respectively), but differences among selections were not significant in two other periods. Low‐yielding TFM 16 had leaves that were more than 20% narrower than those of the other selections. Leaf width was a relatively more stable morphological character than leaf elongation or leaf area expansion rate.
Inheritance and Anatomy of Root Bark Area in Alfalfa1
Authors: Brick M.A. , Barnes D.K.
Published: July 2010

The root bark of alfalfa (Medicago sativa L.) has several important physiological functions, including the storage of carbohydrate reserves. The objectives of this research were to determine the inheritance of alfalfa root bark area and compare the anatomical features of plants with a large and small proportion of root bark. Two sets of six clone diallel mating schemes were made to evaluate general combining ability (GCA) and specific combining ability (SCA) effects for root bark area. S2, F1, and F2 families were produced from selected plants to study qualitative inheritance of root bark area. Two plants with contrasting root bark area were studied histologically to investigate their anatomical features.

General combining ability effects were highly significant and SCA effects were non‐significant for root bark area in both diallel sets. Qualitative analyses indicated that two tetrasomically inherited non‐dominant duplicate genes (RB1 and RB2) controlled bark area. Root cross‐sections taken 63 cm from the root tip of the two plants used for anatomical studies revealed that 33 and 83% of the sectioned area was root bark. Plants with contrasting root bark area could be distinguished shortly after secondary growth was initiated. Alfalfa populations with contrasting root bark composition are being developed for use in physiological and plant breeding studies.
Effect of Defoliation and Depodding on 14CO2 Assimilation and Photosynthate Distribution in Y‐Shaped Soybean Plants1
Authors: Gent Martin P.N.
Published: July 2010

To determine the importance of long distance translocation to the yield of soybeans (Glycine max L. Merrill), field‐grown plants were modified by selective pruning to create an imbalance in the number of leaves and the number of pods on opposing branches of a Y‐shaped plant. The Y‐shaped plants were created early in vegetative growth by pinching off the growing apex when the first trifoliolate leaf appeared. After flowering, one group of these Y‐shaped plants was pruned by removing one‐third of the leaflets and one‐third of the pods from both branches (the even treatment), another group was pruned by removing two‐thirds of the leaflets from one branch and two‐thirds of the pods from the opposite branch (the uneven treatment). Plants given the even and uneven treatment were labelled with 14CO2 on three occasions corresponding to days early, middle, and late in pod‐filling. After 24 h, labelled plants were harvested, dried, and the specific radioactivity in each part and the distribution of radioactivity in the various parts of the plant were determined. Some of the labelled plants were allowed to mature before harvest and analysis.

The changed leaf area of the treatments remained to the end of the season, but the changed pod distribution did not. Increased abortion of pods and seeds on the deleafed branch and decreased abortion on the depodded branch of the uneven treatment equalized the reproductive load on all the pruned branches during most of the pod‐filling period. The pruning had no effect on photosynthesis per unit leaf area, as measured by assimilation of 14CO2, or on the rate of disappearance of radioactivity from leaves in the first few hours after labelling. Moreover, the movement of the radioactivity out of the leaf or into the seed was unaffected. The uneven treatment did induce a change in the amount of photosynthate retained in the stem of the two different branches; the depodded stem retained twice the radioactivity of the deleafed stem after 24 h. The difference in radioactivity in the stems of different treatments noted 24 h after labelling was also found at the end of the season, though the level of radioactivity was reduced by a factor of 2.

The resistance to translocation is sufficient to alter the distribution of concurrent photosynthate to the stem, petiole, and podwall parts but it is not sufficient to change the uptake of photosynthate into the seeds of Y‐shaped plants with an uneven distribution of sources and sinks.
Changes in Alfalfa Cultivars Grown in a Semiarid Environment1
Authors: Rumbaugh M. D. , Johnson D. A.
Published: July 2010

Eight alfalfa (Medicago falcata L. and M. sativa L.) cultivars were seeded on a semiarid dryland site in 1954. In 1979 open‐pollination seeds were harvested, plants were excavated to produce synthetics, and seeds of old stocks were obtained for use as check populations to determine if significant changes in adaptive traits had occurred over the 25 years since establishment. Flower color, emergence of seedlings with limited water and from excessively deep plantings, seedling root length, and the recovery and survival of seedlings following a laboratory drought exposure test were evaluated. No significant changes in flower color were found between the checks and the open‐pollination or synthetic populations although a slight tendency for a higher frequency of blue to purple flowers occurred. Seedling emergence with limited water, seedling emergence from excessively deep plantings, and seedling root length were all greater for open‐pollination and synthetic populations than for the check populations. Surprisingly, however, recovery and survival of seedlings following laboratory drought tests were lower for the open pollination and synthetic populations. Thus, although genetic changes have definitely occurred over the 25‐year life of this stand, it is not certain whether these changes were due to natural selection pressures or to the relative reproductive capacities of M. falcata and M. sativa.
Reduction in Number of Motes in Bolls of Interspecific Hybrid Cotton by Backcross Pollination1
Authors: Bhardwaj Harbans L. , Weaver James B.
Published: July 2010

Motes are cotton (Gossypium spp.) ovules that fail to ripen into mature seeds but develop into aborted structures. These aborted ovules represent a loss in yield and cause imperfections in yarn and cloth quality by causing neps. The number of motes (percentage of ovules that failed to develop into seeds) was studied in interspecific hybrids (ISH) of cotton, which have a higher number of motes, for 3 years (1980‐1982). A cytoplasmic male sterile ISH was hand‐pollinated with pollen from its counterpart fertile‐ISH and strains of parental species (Gossypium hirsutum and G. barbadense). The number of motes in seed‐cotton produced as a result of these hand‐pollinations was compared in 1980 and 1981. The results indicated that the number of motes was dependent upon the male parent used to pollinate the CMS‐ISH. Pollinations with strains of G. hirsutum or G. barbadense resulted in approximately a 50% reduction in number of motes as compared to pollination with counterpart fertile‐ISH. These findings provide an indirect evidence of cryptic structural differentiation in tetraploid species of cotton. During 1982, G. hirsutum backcross plants (grown from seed produced by hand‐pollination in 1981), a fertile upland hybrid, and genotypes of parental species, when grown under open‐pollination, had significantly lower number of motes than fertile‐ISH plants. Out‐crossing to parental species was observed to greatly reduce the number of motes in fertile‐ISH. This is as expected because outcrossing to parental species is similar to backcrossing, which masks the effects of cryptic structural differentiation.
Estimation of Sulfur in Grain by X‐Ray Fluorescence Spectrometry and Its Relation to Sulfur and Aniino Acids of Field Crops1
Authors: Maranville J. W. , Mattern P. J. , Clark R. B.
Published: July 2010

Energy dispersive X‐ray fluorescence spectrometry (EDXRF) is a rapid method of multielement analysis which includes S. Since most S in grain is associated with the S amino acids in protein, a measure of total S concentration might indicate, in part, grain nutritive value. A study was conducted to determine if total S measured by EDXRF was associated with concentration of cystine, cysteine, and methionine of corn (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench], wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merr.] grain. Results showed that total S when determined as a percent of dry weight was positively correlated with S amino acids in the crops investigated. The highest correlation for methionine with S was for wheat (r = 0.913) followed by sorghum (r = 0.893), corn (r = 0.854), and soybean (r = 0.796). Correlations with S were equally as high for cysteine + cystine in these crops. Total S correlated highly with protein levels in sorghum, wheat, and soybean, but not in corn. Sulfur as a percentage of protein was strongly associated with the S amino acids calculated as a percentage of protein in corn, but not in sorghum, wheat or soybean. The N/S ratio was negatively and significantly correlated with S amino acids (percentage of protein) only in corn and soybean. Total S measured by EDXRF and calculated as percent of dry wt appeared to be a reliable indicator of S amino acid content in the crops studied. Total S may be used as an index of S amino acids in grains when crops are being screened for that character in plant breeding programs.
Use of Diverse Populations in Soybean Breeding1
Authors: Khalaf Abdul Ghafour M. , Brossman Gary D. , Wilcox J. R.
Published: July 2010

Eighty random lines from each of two sets of diverse two‐, three‐, and four‐parent soybean [Glycine max (L.) Merr.] crosses were evaluated for agronomic characteristics over a 2‐year period. The objective of the study was to evaluate the relative potential of the three types of crosses as sources of variability for soybean improvement. Progenies from three‐parent [(cultivar ✕ plant introduction) ✕ cultivar] crosses were more variable and had higher frequencies of agronomically superior lines than progenies from either two‐parent (cultivar ✕ plant introduction) or four‐parent [(cultivar ✕ plant introduction) ✕ (cultivar ✕ plant introduction)] crosses. Correlation coefficients among maturity, plant height, and lodging score were consistent with and similar in magnitude to those from crosses among adapted, indeterminate cultivars. Relationships between yield and lodging indicated that progenies from these three‐parent crosses should be good sources of lines with good yield potential and adequate lodging resistance.
Associations Among Morphological and Digestibility Characters in Reed Canarygrass1
Authors: Christensen D. W. , Stuthman D. D. , Hovin A. W.
Published: July 2010

Efficient selection of reed canarygrass (Phalaris arundinacea L.) genotypes would be aided if morphological traits that are associated with yield and digestibility could be identified. The purpose of this study was to examine the relationships among leaf rigidity score (LR), canopy height (CH), tiller number (TN), tiller weight (TW), culm diameter, leaf blade fraction (LF), yield (Y), digestible yield (DY), total forage digestibility (TD), plus sheath digestibility (SD), and leaf blade digestibility (LD) of 10 reed canarygrass clones and their topcross progeny grown in microplots. Four location‐year combinations were sampled. Correlations of Y with DY were very large and positive, while correlations of DY and TD were generally small and negative. Correlations of Y and TD tended to be small and negative. The correlations of TD with SD and LD were large and positive. Correlations of any one morphological trait with Y were generally opposite in sign to the correlations of that trait with TD. Most traits were positively correlated with Y and negatively correlated with TD; the one consistent exception was LF. Traits which were not negatively correlated with LF included LR and TN. Relationships of the traits included in this study suggest that: 1) selection for DY will probably increase only Y; 2) selection for TD while maintaining Y should be possible; 3) selection for TD may be as effective as selection for LD or SD; 4) simultaneous selection for LF, LR, and TN may be effective in identifying high yielding reed canarygrass genotypes which are also highly digestible.
Seasonal Forage Growth Rate and Solar Energy Conversion of Irrigated Vernal Alfalfa1
Authors: Evans David W. , Peaden Richard N.
Published: July 2010

Alfalfa (Medicago sativa L.) yields decrease from early to midseason harvests in all major alfalfa production areas of North America. Warm temperatures typical of midsummer accelerate alfalfa development. The resulting shorter period of growth to harvest maturity thus contributes to midseason alfalfa yield decline. It is not clear whether a reduced rate of dry matter accumulation in midseason also consistently contributes to yield decline. The present study examined successive growth periods of winter‐dormant ‘Vernal’ alfalfa under irrigation in a mid‐latitude, low‐rainfall growing region. Over 2 years, forage growth rates during active growth averaged 18.8 g m−2 day−1 for the second and third (midseason) growth periods within a year. This was higher than in the first and fourth growth periods. During active growth of the first three cuttings each year 1.5% of incident solar energy was accumulated as forage. This declined to 1.2% during the fourth growth period. Results suggest that the portion of the decreased midseason growth resulting from decreased growth rates in temperate alfalfa‐growing regions reflects moisture stress rather than a direct temperature effect.
Effect of the Reproductive Sink on 14C‐Assimilate Partitioning between Starch and Water‐Soluble Compounds in Soybean Leaves1
Authors: Carlson Dale R. , Brun William A.
Published: July 2010

The objective of this study was to determine if changes in reproductive sink demand influence the partitioning of carbon within the source leaf. Temporary (Late R2‐R4) and continuous (Late R2‐R8) light and CO2 enrichment treatments were used increase the pod number and weight on field.grown soybeans (Glycine max L. Merr. ‘Hodgson 78’). During the last week of the temporary treatment, and at 1, 2, and 4 weeks thereafter, plants were pulse‐labeled with 144CO2 at the tenth trifoliolate leaf. Leaf discs were removed at 0.5, 2, 4, 8 and 24 h after labeling and subsequently extracted for determination of 14C in the starch, water‐soluble compounds (WSC), and residual fractions. Temporary and continuous CO2 and light enrichment increased the reproductive sink load of field.grown soybeans at all sampling dates. On the average, total number of pods was increased 35% by light enrichment, and 38% by CO2 enrichment. During this same period, light enrichment res~resulted in at least a 38% increase in total pod wall and seed dry weight while CO2 enrichment resulted in a 28% increase. Light and CO2 enrichment increased plant size during the sampling period. Leaf dry weight was increased 30% by light enrichment, and 39% by CO2 enrichment. Stem plus petiole dry weight was increased 26% by light enrichment and 51% by CO2 enrichment. Hence, light enrichment had a greater effect on reproductive than on vegetative growth, while CO2 enrichment had a greater effect on vegetative than on reproductive growth. On the first sampling date, 11 August, significantly less label was incorporated and retained as starch in the light‐enriched plants. No differences were observed in the levels of 14C‐labeled WSC or starch for the light‐enriched plants on 18 and 25 August, and during the entire experiment for the CO2‐enriched plants. On 7 September, 4 weeks after removal of the temporary treatment, significantly less label was retained as WSC, starch, and residual material in the light‐enriched plants. The hypothesis that increased sink demand may influence assimilate partitioning is supported by these data.
Method for Monitoring Nitrogen Gas Exchange from Plant Foliage
Authors: Weiland R. T. , Omholt T. E.
Published: July 2010

Current techniques used to monitor nonelemental N forms evolving from plant tissue have sampling limitations. This research was undertaken to measure NH3 and NOx (NO and/or NO2) gas exchange from plant foliage in the field which allowed for multiple samplings and used solid trapping materials. Ambient air was passed over a maize (Zea mays L.) leaf and then through two N gas traps connected in parallel. Ammonia was absorbed in a H+ ‐ saturated cation exchange resin. Any trapped NH3 was then eluted with acid and colorimetrically quantified. In the first section of the second trap any NO was oxidized to NO2 when passed through K2Cr2O7/H2SO4 coated glass beads. Triethanolamine impregnated molecular sieve removed NO2 in the second section. The absorbed N was extracted with triethanolamine and colorimetrically quantified as NO−2. A corresponding system omitting the leaf was operated simultaneously to determine ambient NH3 and NOx air concentrations and to correct for net losses of gaseous N compounds evolved from the leaf. Measurements with this system made with field‐grown maize plants over the 1983 growing sea.son indicated that the total foliar N loss did not exceed 2 kg/ha season.
Loss of Half‐Sib Families in Mass Selection1
Authors: Burton Glenn W.
Published: July 2010

To study the loss of half‐sib families in mass selection, progenies of seven populations of Pensacola bahiagrass (Paspalum notatum var. saure Parodi) being improved by recurrent restricted phenotypic selection (RRPS) were studied in detail. Accession numbers assigned to progenies of selected plants recorded in spaced‐plant field plans of randomized populations of 990 to 1200 plants per cycle permitted a determination of half‐sib families lost with each cycle of grid selection. Loss of half‐sib families averaged 31.2% per cycle for five populations when the top yielding five plants in 25‐plant blocks were selected in a planting with six randomly placed plants of each family in a population. With only five randomly placed plants of each family, the loss of half‐sib families increased to 38%. Loss of these low yielding half‐sib families permitted more rapid progress than a plant‐to‐row breeding system that would have retained them. In 35 computer‐generated populations with six randomly placed offspring from each of 42 selections, reducing the percent of plants selected from 25.0 to 8.3, increased the percent of half‐sib families lost from 20.3 to 61.2. In four populations that lost 31% of their half‐sib families, 51% of the remaining families were recovered only once whereas 3.3 and 0.8% were recovered four and five times, respectively. Because half‐sib families recovered most frequently were the most productive, mass selection as practiced here permitted more rapid advance than a breeding system requiring equal representation from each family in the polycross for the next cycle.
A Comparison of Intermating and Selfing Following Selection for Heading Date in Two Diverse Winter Wheat Crosses1
Authors: Frederickson L. J. , Kronstad W. E.
Published: July 2010

Response to two cycles of mass selection for heading date involving selfing or intermating was studied in two diverse winter wheat (Triticum aestivum L. em Thell.) crosses (I and II). Selection was bidirectional resulting in early and late‐heading populations for each mating system, cycle and cross. Generation means and variances within crosses were used in a genetic analysis of heading date. Additive effects of genes were an important source of variation in Cross I. Predicted response to selection for heading date was 7.1 and 9.1 days/cycle for 1981 and 1982, respectively. Heading date in Cross II was affected primarily by non‐additive genetic effects. For this cross, progress from selection for heading date was predicted to be 6.9 days/cycle in 1981, and 1.4 days/cycle in 1982. Observed response to bidirectional selection for heading date in Cross I showed gains of −4.8 and 5.5 days/cycle with selfing and −4.2 and 5.1 days/cycle with intermating in 1982. Response to selection for heading date with intermating in Cross II was superior to selfing for earlier heading date (6.0 vs. 5.0 days/cycle) and inferior to selfing for later heading date (0.9 vs. 1.9 days/cycle) in 1982. The latter results were ascribed to an accumulation of minor genes by intermating and rapid fixation of recessive genes due to selfing, for early and late selection, respectively. Recurrent selection with intermating was not more efficient in changing the heading dates of the two populations than selection followed by selfing. The effect of bidirectional selection for heading date under two systems of mating on seven other traits was also studied. Selection for early heading date under both systems of mating in Crosses I and II resulted in shorter plant stature, fewer spikes/plant, and lower biological yield (P = 0.05) at two locations in 1982. Bidirectional selection for heading date under both mating systems had no significant effect on grain yield, 100‐kernel weight, kernels/spike, and harvest index in Crosses I and II.
Location of the Benzoxazinless (bx) Locus in Maize by Monosomic and B‐A Translocational Analyses1
Authors: Simcox K. D. , Weber D. F.
Published: July 2010

The r‐X1 deficiency in maize (Zea mays L.) produces large numbers of monosomics. These monosomics are a unique and useful tool for determining the chromosome location of specific genetic loci. In this study, maize monosomics generated using the r‐X1 deficiency were used to determine the chromosome location of the benzoxazinless (bx) locus. The bx locus is deficient in the production of benzoxazin‐3‐one glucosides, which have been positively correlated with resistance to first‐brood European corn borers, corn leaf aphids, and resistance to northern corn leaf blight. F1 progeny of R/r‐X1; Bx/Bx females crossed by r/r; bx/bx males were screened for monosomic plants expressing the bx phenotype. Karyotypic analysis indicated the monosomic chromosome in such plants was chromosome 4; thus, the bx locus is on chromosome 4. B‐A translocations were then used to confirm the above observation and to determine that the bx locus is in the short arm of chromosome 4. Conventional linkage analysis placed the locus as probably being near Rp4.
A Dwarf Outcrossing Mutant in Common Bean1
Authors: Nagata R. T. , Bassett M. J.
Published: July 2010

This study was conducted to determine if a dwarf mutant in common bean (Phaseolus vulgaris L.) could be used to facilitate outcrossing. In one M2 progeny line of common bean, seven plants were discovered with a dwarf mutant phenotype. Tests of M3 progenies derived from field grown M2 plants revealed outcrossing rates of 5 to 47%. Pollen staining tests using potassium iodide or acetocarmine indicated no unusual pollen abortion rates. Pod set from plants grown in insect‐proof enclosures were comparable to unprotected dwarf plants. Open flowers of dwarf plants manually crossed between 0630 and 1430 h with either ‘Sprite’ or University of Florida breeding line ‘7‐1404’ pollen resulted in cross‐pollinated progeny at the rate of 26 to 86%. The frequency of cross‐pollination declined with time of day. Evidence is presented supporting the hypothesis that delay of anther dehiscence is responsible for the elevated levels of cross‐pollination. The exploitation of this mutant in a breeding program to increase rates of genetic recombination is discussed. The proposed name for this mutant is dwarf outcrossing (do).
Substitution of Cotton Cytoplasms from Wild Diploid Species for Cotton Germplasm Improvement1
Authors: Umbeck Paul F. , Stewart James McD.
Published: July 2010

The purpose of this investigation was to initiate a program of cytoplasm introgression from the wild diploid species into cultivated cotton (Gossypium hirsutum L.) and then use the semigametic trait of Pima cotton (G. barbadense L.) to develop homozygous cytoplasmic‐substituted lines for evaluation and commercial release. It was determined that the in situ pattern of ovule and embryo growth in the wild species is similar to the cultigens but that the wild relatives have a shortened period of boll development, show reduced seed size and weight, have fewer seeds per boll, and in some cases require specific light conditions in order to initiate flowering. Three new interspecific hybrids with wild species cytoplasms were recovered by using four different pollen parent sources, a single application of GA3, at 3.5 mmol L−1 to the flower at anthesis, and embryo rescue techniques. Results indicated that the success of fertilization and embryo development was strongly influenced by the paternal species used to make the cross, and secondly, that the degree of hybrid embryo development may be a more important factor than the age or size at the time of embryo rescue. Immature embryos rescued prior to 15 days post‐anthesis failed to show further development or undergo precocious germination. The optimum time for embryo rescue and recovery occurred between 15 and 25 days after anthesis. Cytogenetic analysis of the hybrids verified that they were true interspecies crosses. Observations of meiotic metaphase chromosomes indicated the degree of relatedness between species. As expected, chromosome pairing indicated a very close homoeology between the G. trilobum DC. ex Skov. (D8) genome and the D subgenome of G. hirsutum. The E genomes of G. stocksii Mast ex Hook. (E1) and G. somalense (Gürke) Mayer (E2) exhibited little homoeology to either the A or the D subgenome of G. hirsutum or the A genome of G. arboreum L. Cytogenetic observations by others on the reciprocal hybrids of these species closely agree with our data on chromosome associations. Thus, there does not appear to be a significant effect of cytoplasm on chromosome pairing in the primary hybrids.
Effectiveness of Stripe Rust Resistance among Lemhi 53 Spring Wheat Near‐Isogenic Lines1
Authors: Griffey C. A. , Allan R. E.
Published: July 2010

Stripe rust (caused by Puccinia striiformis West.) is a major wheat (Triticum aestivum L.) disease in the northwestern USA, and resistance offers the most economic control. This study compared the effectiveness of ‘Lemhi 53’ type near‐isogenic lines that derived stripe rust resistance from 13 diverse sources. Factors considered were grain yield capacity of triadimefon‐treated [l‐(4‐chiorophenoxy)‐3,3‐dimethyl‐l‐(IH‐1,2,4‐triazol‐1‐yl)‐2‐butanonel and untreated plots, percent yield loss, backcross number, stripe rust reaction type, and severity ratings. Pooled mean yields from treated and untreated plots across 1981 and 1982 trials were compared and used to determine percent yield loss due to stripe rust. Lines with similar stripe rust reaction types, both among and within families, varied for yield potential, with and without fungicide, percent yield loss, or both. Lines of families with resistant, moderately resistant, or intermediate stripe rust reaction types proved most useful in preventing grain yield losses. However, certain lines of all stripe rust reaction classes, excepthe susceptible class, had negligible losses. Low inherent yield potential was associated with increased backcross number and combined leaf and stripe rust resistance. In general, subjective ratings of stripe rust reaction type and severity complemented evaluation of the germplasm, but they did not always identify lines with low yield loss and high yield potential. Five lines from different families exhibited high yield potential under stripe rust attack and had yield losses of only 2 to 7%.