bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship Between Weathering Deterioration and Germination, Respiratory Metabolism, and Mineral Leaching from Cottonseeds1
Authors: Woodstock L. W. , Furman K. , Leffler H. R.
Published: July 2010

Germination of cottonseeds (Gossypiura hirsutum L.) is reduced by preharvest exposure to,weather, particularly if conditions are warm and humid. To identify some of the germination processes affected by weathering deterioration, seedlots of six cultivars were harvested before and after a period of field exposure and comparative germination studies were conducted. Seedling field emergence was reduced by 11 to 33% due to weathering. During imbibition, weathered seeds of sensitive cultivars released more K+, Mn2+, Mg2+, and Ca2+, but less Na+ into the steep solution than did their unweathered counterparts. Leaching of individual minerals was a better indicator of seed quality than was the total release of electrolytes; release of K+ Ca2+ than was significantly correlated with measurementosf seed quality. Respiratory O2 uptake was reduced in deteriorated seeds, with elevated estimates of the RQ after 7.5 h of imbibition. Aeration with 100% O2 increased O2 uptake and reduced the RQ, indicating that O2 diffusion may have limited respiration during early germination. Weathering deterioration of membranes was confirmed by electron microscopy of cotyledonary lipid and protein bodies. Thesed ata indicate that the loss of membrane functional integrity is a major factor responsible for the reduction of germination potential by weathered seeds, and that the release of K+ and Ca2+ into steep water during imbibition may be a good indicator of cottonseed planting quality.
Methods for Combining Data from Gemrplasm Evaluation Trials1
Authors: Hill R. R. , Rosenberger J. L.
Published: July 2010

Seven different methods of combining total season yields from a series of alfalfa (Medicago sativa L.) germplasme valuation trials at a single location were evaluated. Our objective was to find the “best” method for estimating mean yields for the cultivars and experimental ines included in a series of trials that did not contain all entries in equal numbers. The methods of estimation included percent of checks, summation of differences between entries and checks, an unweighted two‐way analysis with trials and entries as factors, a weighted two‐way analysis, and three versions of best linear unbiased prediction (BLUP). The versions of BLUP involved different estimates of the entry and environmental variance components. The trial series included 150 different entries (cultivars ande xperimentasl ynthetics) that had been evaluated in one to 14 trials between 1975 and 1982. Eleven of these trials had data for total yield for each of three growing seasons. Each of the methods of estimation were conducted with each of the 11 complete trials omitted from the data set, and estimates were used to predict means for the omitted trial. The method with smallest prediction error was judged “best.” The smallest prediction errors were obtained with the version of BLUP in which the entry and environmental variances were estimated from an unbalanced two‐way (trials and entries) analysis of variance. The second best method was the version of BLUP in which environmental and entry variances were estimated from the pooled sums of squares over trials. The version of BLUP in which variances were estimated for each trial ranked third and was only slightly superior to the summation of differences, unweighted, and the weighted analyses. The percent of checks had the largest prediction errors of all the methods we evaluated.
Evaluation of Physical Grain Quality in the BS17 and BSI (HS)CI Synthetics of Maize1
Authors: LeFord D. R. , Russell W. A.
Published: July 2010

The objective of this study was to determine the potential for selection of maize (Zea mays L.) genotypes that produce grain resistant to physical injury and to study relationships among physical grain traits during inbreeding. Materials evaluated were S1 and S2 lines derived from BS17 and BSI(HS)C1. Eight traits (kernel shear strength, visual endosperm rating, date of anthesis, grain harvest moisture, grain‐breakage susceptibility, weight per 300 kernels, volume per 300 kernels, and kernel density) of BS 17 S1 and S2 lines were evaluated in 1979 and 1980, respectively, and of BSI(HS)CI S1 and S2 lines in 1980 and 1981, respectively. All materials were grown at two locations. The analyses of variance combined over environments revealed that significant genetic variability among genotypes existed for all traits. Genotype ✕ environment interactions were generally significant for all traits except shear strength and kernel density. Estimated genotype ✕ environment interaction variance components were 0 to 66% as large as estimated genotypic variance components. Variance component heritability estimates (entry‐mean basis) for grain breakage ranged from 0.48 to 0.73. The optimum harvest moisture range for preservation of physical grain quality was 19 to 26%. Deviations from this optfimum grain moisture range resulted in increased grain breakage susceptibility. Grain resistant to breakage tended to be smaller, denser, and higher in shear strength. Correlations between traits indicated that entry means of S1 line traits would have predictive value for the same traits of the S2 lines. The data indicated that selection of S2 lines for breakage‐resistant grain would cesult in earlier‐flowering S2 lines with smaller kernels.
Anatomy, Morphology, and Growth of Tall Fescue Rhizomes1
Authors: Jernstedt J. A. , Bouton J. H.
Published: July 2010

Tall fescue (Festuca arundinacea Schreb.) reportedly produces rhizomes, but the anatomy, morphology, and growth of rhizomes have not been adequately studied. Our objective was to determine if lateral shoots were true rhizomes and distinguishable from tillers. Rhizomatous and nonrhizomatous genotypes were selected from the field for studies and comparisons with rhizomes of Kentucky bluegrass (Poa pratensis L.). Microscopic examination showed rhizomes of both species had a spongy cortex, a large pith area, one to two rings of alternately spaced vascular bundles, and sclerified bundle sheaths which merge with a ring of sclerenchyma separating the vascular tissue from cortical parenchyma. In contrast, tillers of tall fescue had numerous and closely spaced vascular bundles, and a densely packed pith region. Based on overall structure, pattern of growth, and internal anatomy, some tall fescue genotypes spread by true rhizomes, equivalent to those of other grasses.
Fall Dormancy of Alfalfa in Transplanted vs. Direct‐Seeded Nurseries1
Authors: Viands D. R. , Teuber L. R.
Published: July 2010

Fall dormancy of alfalfa cultivars and experimental synthetics is routinely evaluated by breeders to predict winterhardiness. Some researchers establish evaluation nurseries by direct‐seeding, followed by thinning the seedlings. Other researchers start seedlings in the greenhouse and transplant them to the field at the desired spacing. Transplants usually have highly branched root systems, whereas direct‐seeded plants primarily have a taprooted system. Because of these different types of root systems, transplanted and direct‐seeded plan~s were compared for fall dormancy by two experiments, one with 17 cultivars and the other with nine cultivars. Each cultivar was established by both transplanting and direct‐seeding in the spring. Fall dormancy of individual plants was rated according to plant height about 5 weeks after the last forage harvest (harvested 7 September). Correlation coefficients between transplant methods (r = 0.99, P<0.01 and r = 0.96, P<0.01 for fire two experiments) and non significant establishment method ✕ cultivar interactions clearly demonstrated that either method provides reliable fall dormancy evaluation of synthetics.
Biotype E Greenbug Resistance in Wheat Streak Mosaic Virus‐Resistant Wheat Germplasm Lines1
Authors: Tyler J. M. , Webster J. A. , Smith E. L.
Published: July 2010

A new source of biotype E greenbug [Schizaphis graminum (Rondani) l resistance was identified in greenhouse screening tests from a group (CI 17881–17886) of wheat (Triticum aestivum L.) germplasm lines previously released as resistant to wheat streak mosaic virus (WSMV). The germplasm release statement from the South Dakota Agric. Exp. Stn. identified the pedigree of these lines as CI 15092/T. speltoides//‘Fletcher’ (CI 13985) /3/ 5*‘Centurk’ (CI 15075). Our objective was to determine the parental source of the greenbug resistance and to quantify the components of resistance. The particular T. speltoides accession used in the cross was unknown; however, it appeared to be the donor of the greenbug resistance, because the other parents of the cross were susceptible to biotype E in greenhouse tests. CI 17882 and CI 17885 exhibited the highest levels of resistance. The resistance in these lines is a new source that can be exploited in the development of greenbug‐resistant wheat germplasm. New sources of greenbug resistance are needed because of the periodic occurrence of new biotypes.
Phenotypic Correlations Between Metal Tolerance and Morphology in Festuca rubra L.1
Authors: Huff D. R. , Wu L.
Published: July 2010

Phenotypic correlations between Zn and Cu tolerance and a range of morphological characters were examined for three populations of red fescue (Festuca rubra L.) grown under noncompetitive conditions. The three populations were a commercial cultivar, Pennlawn, a Zn‐tolerant cultivar, Merlin, and a Cutolerant ecotype, Stirling. Twenty‐three morphological characters were examined for each population. Significant differences for tolerance index were found within as well as between populations for both Zn and Cu. A Spearman's rank correlation analysis for single morphological characters and a multiple regression analysis for grouped morphological characters did not reveal any substantial relationship between Zn or Cu tolerance and morphological characters in any of the three populations. Therefore, random selection for morphological characters within the Zn‐ and Cu‐tolerant ecotypes of F. rubra should not alter their tolerance.
Short‐Branch and Cluster‐Fruiting Habit Inheritance in Crosses of Eight Cotton Lines1
Authors: Coffey Brian N. , Davis Dick D.
Published: July 2010

The potential value of fruiting branches (sympodia) of intermediate length in an ideotype for a high‐yielding line of F1 hybrid cotton grown for stripper harvest led us to research for modifier genes that affect the expression of alleles at the two known major gene loci (cl1 and cl2 that exert primary control over sympodial length. Six stocks of Gossypium hirsutum L., and two G. barbadense L. stocks representing three basic branching habits, normal (Cl1 Cl1 Cl2 Cl2), cluster (cl1 cl1 cl2 cl1 Cl2), and short branch (Cl1 Cl1 cl2 cl2), were crossed in all possible one‐way combinations to assess the expression of the mutant alleles in the F1 generation in various genetic backgrounds. Lateral internode distance to the first fruiting form (square) was measured at the ninth vertical node in the parental and F1 field‐grown populations. Twenty of the 25 crosses showed full dominance of the normal allele over the mutant allele. However, five of the crosses were bimodal with a progeny class of intermediate length occurring in addition to a dominant normal length class. This was interpreted to mean that one or both of the parental lines involved harbored a gene that modified the dominance relationships between the normal and mutant genes conditioning sympodial length. Modified activity in cluster (cl1) expression was observed in four crosses, and modified short‐branch (cl2) expression was detected in one cross.
Diallel Analysis of Aluminum Tolerance in Selected Lines of Grain Sorghum1
Authors: Boye‐Goni S. R. , Marcarian V.
Published: July 2010

A half‐diallel cross involving three Al‐tolerant and three Al‐sensitive sorghum genotypes as identified through a screening test was used to study the inheritance of Al tolerance in grain sorghum [Sorghum bicolor, (L.) Moench]. Data from the Ft generation and parents were analyzed using the Grilllng and the Jinks‐Hayman methods of diallel analyses. Highly significant general combining ability (GCA) and specific combining ability (SCA) effects were observed for the Al‐tolerance trait. The GCA effects were much more important than SCA effects, the ratio being 9:1. From the Vr‐Wr graph, the Al‐tolerance trait showed predominantly additive genetic effects with some degree of dominance. The six parents fell into four groups according to the relative level of dominance: (i) highly dominant (AK 3010, 182), (ii) moderately dominant (NB 9040), (iii) moderately cessive (‘Texas Blackhull Kafir’), and (iv) highly recessive 3001 and AK 3006). The average degree of dominance was partial. Heritability of Al‐tolerance in the genotypestudied was high. Narrow‐sense and broad‐sense heritabilities were 78 and 99%, respectively. The additive gene action and the high heritability for this trait should make either pedigree breeding or recurrent selection successful for the development of Al‐tolerant grain sorghum inbreds.
Visible Indicators of Phsiological Maturity Barley1
Authors: Copeland Philip J. , Crookston R. Kent
Published: July 2010

Visible indicators of maturity have recently been identified for several agronomic crops. Both researchers and farmers have been able to make use of these indicators. We conducted field experiments to identify visible indicators of physiological maturity (PM) in barley (Hordeum vulgare L.). Two cultivars in 1981 and six cultivars in 1982 were selected to represent a diversity of morphological types and genetic backgrounds. Physiological maturity was defined as the attainment of maximum kernel dry weight and was identified by determining the apex of a cubic polynominal curve fitted to kernel dry weight data. Visible changes in the barley plant were evaluated for consistency and closeness to date of PM and to date of 95% maximum kernel dry weight (MKW).

Loss of green color from the glumes and from the peduncle coincided most closely with PM. Loss of green color from the peduncle was more readily observable in the field. First appearance of the pigment strand in the kernel crease, thought to be analogous to black layer development in corn (Zea mays L.), occurred between −1 and 4.5 days after PM. Loss of green color from the flag leaf blade occurred close to the date of 95% MKW. Average percent kernel moisture at time of 9% MKW ranged from 45 to 50% at PM from 18 to 39%.
Photoassimilate Partitioning of Main Shoot Leaves in Field‐Grown Spring Barley1
Authors: Lauer Joseph G. , Simmons Steve R.
Published: July 2010

Premature tiller mortality could conceivably limit grain yield production in barley (Hordeum vulgare L.). Knowing photoassimilate partitioning patterns during the vegetative development phase of growth is important for understanding the causes of tiller mortality. A field experiment was conducted to ascertain the 14C translocation patterns of individual main shoot leaf blades during the pre‐anthesis period for three spring barley genotypes differing in tiller production and survival. One of the top three to five leaves was labelled with 14CO2 on each date and above‐ground plant parts were harvested for determining the distribution of 14C after a 24 h translocation period. Also, for two of the leaves, labelled plants were allowed to translocate until anthesis or maturity before the distribution of radioactivity was measured. Most 14C fixed by the first developed leaves on the main shoot was translocated to newly emerging main shoot leaves or to young tillers. The leaf subtending and the leaf above a particular tiller preferentially exported carbon to that tiller. During the early tiller production phase of growth, proportionately more 14C was translocated to tillers of the higher tillering genotypes than for the lower tillering one. During the time when tiller mortality became evident, no differences in partitioning patterns were found between the high or low tiller mortality genotypes. Later formed leaves in all genotypes provided relatively large proportions of labelled photoassimilate to the main shoot stem and inflorescence. A sharp decline in the percentage of 14C translocated to all tillers occurred when the main stem began rapid growth. We conclude that the shift in main shoot photoassimilate translocation away from tillers and to the main shoot stem contributes to the premature abortion of tillers in barley.
Variation for Nitrogen Fixation Among Progenies of a Virginia ✕ Spanish Peanut Cross1
Authors: Arrenddell S. , Wynne J. C. , Elkan G. H. , Isleib T. G.
Published: July 2010

One method of increasing symbiotic N2 fixation is to improve the N2‐fixing potential of the host plant. Peanut (Arachis hypogaea L.) cultivars of the Virginia (ssp. hypogaea var. hypogaea) and Spanish (ssp. fastigiata Waldron var. vulgaris Harz.) types differ in their ability to fix N2. This study's objective was to determine the variation and relationship of traits indicative of N2 fixed for late generation progenies from the cross of a Virginia and Spanish cultivar. The variability for traits indicative of N2 fixation activity was investigated for 30 F2 families in the F5 and F6 generation from the cross of the Virginia cv., NC 6, and the Spanish breeding line, 922. Nodule number, nodule weight, nitrogenase activity measured by acetylene reduction, specific nitrogenase activity, and shoot weight were measured at three sampling dates at two locations for 2 yrs for the parental lines and F2 families. Fruit weight was determined on the final sampling date for all entries. Cultivar NC 6 was superior to 922 for all measured traits except specific nitrogenase activity. Significant variation was observed among families for most traits. Broad sense heritability estimates for nodule number, nodule weight, nitrogenase activity, shoot weight and fruit weight were moderate to high, indicating that superior genotypes within this population could be readily identified. Nodule number and weight were positively correlated with each other and with nitrogenase activity, suggesting that only nitrogenase activity was required to identify superior families. Phenotypic and genotypic correlations of nitrogenase activity with shoot weight were significant with genotypic correlations ranging from 0.66 to 0.89 over sampling dates and environments. However, correlations of nitrogenase activity and yield were lower (0.36 for F5, 0.57 for F6 and 0.47 over generations) suggesting that nitrogenase activity has less effect on fruit weight than on shoot weight. Selection for families with greater N2‐fixing activity should be possible and should result in indirect selection for yield.
Barley, Wheat, and Triticale Grain Yield in Relation to Solar Radiation and Heat Units1
Authors: Puri Y. P. , Qualset C. O. , Miller M. F. , Baghott K. G. , Jan C. C. , De Pace C.
Published: July 2010

High grain yields (6 to 10 t/ha) of spring habit small grain cultivars are typically obtained in the Tulelake Basin of northern California (41°58′N, 121°28′W, 1230 m elevation) in the April to September growing season. In an attempt to identify environmental factors important in attaining high grain yields, a 3‐year study with four dates of planting (17 April to 7 May) and four seeding densities (100 to 400 seeds/m2) were used to modify the crop growth cycles of seven cultivars or populations of barley (Hordeum vulgare L.), wheat (Triticum aestivura L.) and triticale (X Triticosecale Wittmack). Solar radiation and heat units (maximum air temperature −5°C) were computed for each of three growth periods: early vegetative (EVP), early reproductive ERP), and late reproductive (LRP). Grain yields declined later planting dates; wheat and triticale were more strongly affected than barley. There was little effect of seeding densities on grain yields. Path coefficient analysis revealed the following relationships: Solar radiation, while strongly and positively cor. related with the length of early vegetative period (EVP) in all three crops, was negatively related to grain yield per day, while heat units positively affected the rate of grain yield formation during EVP. Both solar radiation and heat units were positively related to the length of the late reproductive period (LRP) all three crops. For barley there was a strong negative effect of solar radiation and heat units during the LRP on grain yield per day, in contrast to the strong positive effect of these parameters on wheat and triticale. These results suggest that barley required less solar and heat unit energy than wheat and triticale to produce maximum grain yield. Higher temperature and lower solar radiation during the early vegetative period appeared to be beneficial for all three crops.
Temperature Effects on Dark Respiration Among Diverse Sorghum Genotypes1
Authors: Gerik Thomas J. , Eastin Jerry D.
Published: July 2010

Dark respiration is a key physiological process of plant growth and maintenance, but information is limited regarding its genetic variability in grain sorghum. The objectives of this study were i) to determine the range of variability for genetically diverse grain sorghum [Sorghum bicolor (L.) moench] lines and hybrids over a range of temperatures, and ii) to characterize the relationship between dark respiration of a plant during vegetative development and a panicle during grain filling. Dark respiration rates of shoots were determined under controlled conditions at temperatures ranging from 13 to 40°C. At 23°C, the mean rate of dark respiration was 27 μmol CO2 kg−1 s−1 with a range of 32 μmol CO2 kg−1 s−1. Plant growth at near optimum temperatures (30/25°C; day/night) was correlated with dark respiration rates (measured at 29°C) when the rates were expressed on a per shoot basis, but not when expressed on a dry weight basis. Genotypes differed in their sensitivity to temperature. for the genotypes studied, the linear regression coefficients of dark respiration on temperature ranged from 1.1 to 2.5 μmol CO2 kg−1 s−1 °C−1 over the 13 to 40°C range. Within the limits of this experiment, there appears to be sufficient variability to select high and low respiring grain sorghum genotypes and to distinguish those which possess high or low sensitivity to temperature. Panicle dark respiration rates were 50% lower than those of the vegetative portion of the plant. Both panicle and vegetative shoot dark respiration responded in a linear manner to temperature from 13 to 40°C. The panicle dark respiration increased at a rate of 0.75 μmol CO2 kg−1 s−1 °C−1 compared with 1.5 for the vegetative shoot indicating that panicle dark respiration was less sensitive to temperature than was shoot dark respiration. This may be related to the linear nature of dry matter accumulation in grain sorghum panicles grown under divergent temperature environments.
Comparison of Cotton Germplasm Collections for Seed‐Protein Content1
Authors: Kohel R. J. , Glueck J. , Rooney L. W.
Published: July 2010

Gossypium hirsutum L. germplasm from the cultivated and center‐of‐origin collections were evaluated for seed‐protein content (N ✕ 6.25) to provide information for potential selection and genetic modification of cottonseed quality. Whole, acid‐delinted, dried cottonseed were digested for nitrogen determinations by automated microkjeldahl procedures. These data were combined with previous evaluations of physical characteristics and seedoil content, and this information provided the basis to compare collections of cultivated Upland germplasm with exotic centerof‐origin germplasm. Differences in seed constituents between collections and the size of correlations between seed constituents suggests that the potential exists to modify cottonseed quality.
Polyacrylamide Gel Electrophoresis for Cultivar Identification in Tobacco1
Authors: Wilkinson C. A. , Mulchi C. L. , Aycock M. K.
Published: July 2010

Polyacrylamide gel electrophoresis (PAGE) has been demo onstrated as a potential tool for cultivar identification in several crop species; however, information concerning tobacco is generally lacking in the literature. Plants from 10 cultivars representing Maryland and burley air‐cured, flue‐cured, and cigar tobacco types were grown in the field and in two separate greenhouses. Leaf samples were collected and frozen in liquid N2 at three maturity dates (32, 40 and 60 days after transplanting). Isozyme separations were performed using PAGE for esterase, catalase, malate dehydrogenase, and peroxidase with the number of bands identified for each enzyme combined over cultivars and treatments being 3, 7, 9, and 11, respectively. Leaf material from the earliest maturity dates exhibited the highest number of isozymes and the greenhouse environments produced fewer bands per enzyme than the field environment. No cultivar differences were observed for esterase; however, cultivar groupings were observed for the three other enzymes investigated. Peroxidase and catalase exhibited the greatest potential for use in cultivar identification. Identification of the 10 cultivars using a single enzyme at a given maturity date was not accomplished; however, it was possible to separate the cultivars using one or more enzymes over environments and maturity dates. The technique does have potential for practical application; however, some additional refinements in procedures appear in order to reduce the time requirements during extraction.
A Field Technique for Screening for Genotypic Differences in Root Growth1
Authors: Robertson B. M. , Hall A. E. , Foster K. W.
Published: July 2010

There is an interest in breeding for deep, extensive root systems to increase crop yields in semiarid environments. Our objective was to develop a field technique with which large numbers of genotypes could be tested for this trait. The experiments were conducted with cowpea (Vigna unguiculata [L.] Walp.) grown on stored soil moisture in the field (coarse‐loamy, mixed, thermic Haplic Durixeralf). The herbicide, metribuzin, was banded into the root zone at sowing at specific depths and lateral distances from the seed rows. In the main field trial, lateral distances of 46, 61, and 76 cm were tested in combination with vertical herbicide bands of 30 and 15 cm at average vertical depths of 53 and 60 cm, respectively, and with herbicide rates of 4.5 and 9.0 kg active ingredient ha−1 in the band. Plant leaves were observed for herbicide symptoms. With this technique, we succeeded in detecting the progress of root growth in the field. Herbicide symptoms consistently developed soonest in plants which were closest to the herbicide band, in either the horizontal or vertical direction. We also succeeded in detecting significant genotypic differences in mean numbers of days to first herbicide symptoms among five cowpea genotypes; California Blackeye #5 and Grant developed symptoms the earliest, 8006 and PI302457 developed symptoms the latest, and PI293579 was intermediate. With four replicates of two‐row plots, mean genotypic differences of 2 to 3 days were usually significant at the 5% level. The ranking of genotypes obtained with this herbicide‐band technique was consistent with estimates of relative depth of effective rooting obtained from soil moisture extraction measurements. Prior to using this technique in different environments, or to screen other crop species, tests should be conducted to determine the most appropriate herbicide, rate of application, and band location in the soil profile. This technique requires fairly uniform soil throughout the root zone, and relatively uniform genetic material. We conclude that this herbicide‐band technique can be used to screen large numbers of genotypes in the field for the presence of rapid root growth. For short season crops, rate of root growth in the first 2 months in the field should be a good predictor of final extensiveness and depth of rooting.
Comparison of ‘Maris Kabul’ with ‘Vertus’ Alfalfa for Resistance to Verticillium Wilt1
Authors: Viands D. R.
Published: July 2010

With the recent introduction of Verticillium wilt (VW), caused by Verticillium albo‐atrum Reinke & Berth., on alfalfa (Medicago sativa L.), many North American alfalfa breeders have been using European cultivars as sources of resistance. The objective of this research was to compare the inheritance of VW resistance in plants selected from the European cultivars ‘Vertus’ and ‘Maris Kabul,’ each deriving at least some of its resistance from different origins. Qualitative genetic analyses complemented by quantitative genetic analyses were done on four sets of complete diallels (S1's, F1's, and reciprocals) within each cultivar and two sets of Design II matings between Vertus and Maris Kabul for valid comparisons, parents were chosen so that each set was represented by one parent for each of five disease severity classes based on topgrowth symptoms. Disease evaluations were done on about 12‐week old seedlings in growth chambers, 6 weeks after inoculation. Many of the Maris Kabul S1's and moderately to highly resistant ✕ susceptible crosses had definite bimodal distributions, suggestive of a dominant gene conditioning moderate to high resistance. However, inheritance apparently was more complex than any single gene model according to qualitative analyses. Although inheritance in Vertus progenies also appeared to he complex, the absence of definite bimodal distributions suggested that the inheritance differed from that in the Maris Kabul progenies. The hypothesis of different inheritance in these plants from the two cultivars was supported by progeny distributions in Vertus ✕ Maris Kabul crosses. Furthermore, quantitative genetic analyses indicated thai nonadditive genetic effects were about four‐fold larger in these Maris Kabul progenies than in these Vertus progenies. Both sources of resistance appear useful for developing highly resistant cultivars. More stable resistance might be possible from the combination of genes from the two cultivars.
Heritabilities and Associations of Nodule Mass and Recovery of Bradyrhizobium japonicum Serogroup USDA 110 in Soybean1
Authors: Greder R. R. , Orf J. H. , Lambert J. W.
Published: July 2010

Information is needed on the feasibility of breeding to increase the contribution of fixed N2 to the seed yield and protein content of soybean [Glycine max (L.) Merr.]. The objectives this study were to: i) determine the heritabilities of nodule mass as formed by indigenous bradyrhizobia and of percent recovery of Bradyrhizobium japonicum (Kirchner) Buchanan serogroup USDA 110, ii) examine the relationship betweenodulation ability with indigenous bradyrhizobia and the ability to selectively form nodules with an inoculant strain of B. japonicum, and iii) determine the influence of nodule mass and percent recovery of serogroup USDA 110 on seed yield and other agronomic traits. Four selected plant introductions were crossed to form three populations. Random F3‐derived, F5 and F6 lines (F3:5, F3:6) from these populations were grown in the field at three locations in Minnesota during 1982. Heritability estimates for indigenous nodule mass, on an entry mean basis over locations, ranged from 54 to 67% for the three populations. This result suggests progress in selecting for increased nodule mass with native bradyrhizobia should be possible. A positive relationship of nodule mass to seed yield was observed indicating that further selection for increased nodulation with the native bradyrhizobia may be warranted. Heritability estimates over locations for percent recovery of serogroup USDA 110 ranged from 26 to 52% for the three populations. Inoculation with strain USDA 110 increased seed yield at two locations and nodule mass at one location. The percentage recovery of serogroup USDA 110 was significantly increased (P = 0.05) from a background level of 1.6% to average of 9.9% in the inoculated rows. However, percent recovery of serogroup 110 was not correlated with seed yield or seed protein. Ability of a line to nodulate preferentially with serogroup USDA 110 was not dependent on the line's relative ability to nodulate with the indigenous strains.
Use of Allozymes as Genetic Markers for Predicting Performance in Maize Single Cross Hybrids1
Authors: Frei O. M. , Stuber C. W. , Goodman M. M.
Published: July 2010

The possible use of allozymes in inbreds of maize (Zea mays L.) for predicting single cross performance has been proposed by many maize breeders. This potential use was evaluated in an experiment involving a large group of publicly available inbreds. The six testers, B73 and B14A (Stiff Stalk type), Mol7 and Oh43 (Lancaster type), K55 (from ‘Pride of Saline’), and T8 (from ‘Jarvis’) were chosen, each representing different germplasm sources (populations). Based on allozyme genotypes at 21 enzymeloci, a genetic relatedness measure of 406 inbreds with the six tester lines was generated and line pairs were classified into similar (SA) or dissimilar (DA) allozyme groups. A second genetic relatedness measure was based on pedigrees. Lines derived from the same population were considered to have similar pedigrees (SP); lines derived from different populations were classified as having dissimilar pedigrees (DP). Each tester was crossed to a set of lines (usually five) from each of the four allozymepedigree combinations. Different sets of lines were used for the single crosses with each of the testers. These single crosses were field tested in seven environments. Significantly higher yield (10%) was observed in the DA class than in the SA class. The DP class outyielded the SP class by 37%. In spite of the highly significant main effects of allozymes and pedigrees, allozyme dissimilarity was associated with higher yield only when the pedigree background was similar (SP‐class). In hybrids of lines from different populations (DP‐class) the allozymes showed no association with yield. Neither allozymes nor pedigrees were associated with yield in crosses to B73, indicating that exceptions from the general associations occur, depending on the tester.
Comparisons Between P‐Fertilized and Mycorrhizal Plants1
Authors: Pacovsky R. S. , Bethlenfalvay G. J. , Paul E. A.
Published: July 2010

In experimentation with vesicular‐arbuscular mycorrhizal (VAM) fungi, the availability of non‐VAM control plants of equal size to VAM plants is a fundamental requirement. The purpose of this work was to determine nutrient regimes needed to achieve growth equivalence between VAM and non‐VAM plants. Soybean [Glycine max (L.)Merr.] cv. Amsoy 71 and sorghum [Sorghum bicolor (L.) Moench] cv. Bok 8 plants were grown under controlled conditions in a soil (Josephine silty clay loam, mesic Typic Haploxerult) low in plant‐available P. Soybeans were inoculated with one of four species and sorghum with one of two species of VAM fungi. Non‐inoculated control plants received nutrient solutions that contained 0.0, 0.2, 0.4, or 1.0 mM P. while the growth of P‐supplemented controls may be equivalent to VAM plants, an important question remains: Are these plants also equivalent in terms of such functional parameters as leaf development, dry matter partitioning, and nutrient assimilation? The objective of this experiment was to answer these questions. The response to VAM colonization was similar in both hosts, although less extensive colonization was observed in sorghum. Dry weight, leaf area, and P content increased exponentially with nutrient solution P level. Plants colonized with VAM fungi grew 3 to 6 times larger than the P‐free controls but attained only 35 to 65% of maximum growth possible with high fertilizer P input. Host response to VAM colonization was equivalent to that of plants receiving between 0.12 and 0.22 mM P for phytomass, leaf area, and N content. Mycorrhizal plants contained less P, Mn, and root Fe but more Zn and Cu than comparable plants fertilized with P. It was concluded that P‐treated, non‐VAM plants differed physiologically and anatomically from VAM plants of equivalent size grown under P stress. It may therefore be necessary to establish the comparability of VAM plants and of “VAM‐equivalent controls” separately for each plant parameter of interest. Even then, differential growth responses in VAM‐host associations may prevent complete comparability between VAM and P‐fertilized plants.
Identification of Cultivars of Perennial Ryegrass by SDS‐PAGE of Seed Proteins1
Authors: Ferguson J. M. , Grabe D. F.
Published: July 2010

The number of cultivars of perennial ryegrass (Lolium perenne L.) continues to grow. Accurate and rapid laboratory techniques to differentiate between cultivars has become increasingly important for both consumer protection and plant variety protection. The purpose of our work was to develop an electorphoretic procedure for ryegrass seed which would differentiate cultivars of perennial ryegrass. Proteins were extracted from ground seeds of 28 perennial ryegrass cultivars. Extracts were analyzed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDSPAGE) procedures. A total of 27 bands were present with many of the bands common for the 28 cultivars. Cultivars were characterized by presence or absence of specific bands and by band intensity ratios calculated from densitometer scans. The cultivars Pennant and Premier were not successfully differentiated from each other nor was ‘Omega’ found to be different from the cultivar Birdie. All other cultivars were differentiated by unique banding patterns. Banding patterns from SDS‐PAGE of proteins were not affected by year and location of production, class of certified seed, or viability and vigor of the seed.
Cell‐Wall Concentration and Components in Stratified Canopies of Alfalfa, Birdsfoot Trefoil, and Red Clover1
Authors: Buxton D. R. , Hornstein J. S.
Published: July 2010

Much of the Variability in digestibility and voluntary intake of herbage is closely associated with variation in cell‐wall (CW) concentration and components. This study was conducted to compare CW characteristics of total herbage and plant parts of alfalfa (Medicago sativa L.) birdsfoot trefoil (Lotus corniculatus L.), red clover (Trifolium pratense L.), and white clover (Trifolium repens L.), and to evaluate relationships between CW characteristics and in vitro digestible dry‐matter (IVDMD) concentration. Plants were sampled four times during spring growth and three times during summer regrowth. With the exception of white clover, subsamples were divided into leaves (leaf blades) and stems (remaining plant) and grouped by stem‐node segment. The CW concentration in total herbage generally was least in white clover and greatest in alfalfa. Within species, CW concentration was least for leaves and greatest for stem segments from plant bases. Stems of red clover had a lower CW concentration than stems of alfalfa or birdsfoot trefoil. Cell‐wall lignin concentration was greatest in birdsfoot trefoil and least in the two clover species. Within species, CW‐lignin concentrations of leaves and stems were similar. Both CW and CW‐lignin concentrations were inversely related to IVDMD concentration in stem segments and total herbage with correlation coefficients ranging from –0.40 to –0.98. The relationships was inconsistent in leaves. Inclusion both CW and CW‐lignin concentrations in linear multiple‐regression equations acounted for 95 and 84% of the observed variation in IVDMD concentration in stems and total herbage, respectively.
Normal vs. Okra Leaf Yield Interactions in Cotton. II. Analysis of Vegetative and Reproductive Growth1
Authors: Wells Randy , Meredith William R.
Published: July 2010

Past studies on differences in growth between Okra(L2°,L2°) and normal (broad‐leaved l2l2) cottons (Gossypium hirsutum L.) have routinely used Okra lines derived from backcrossing the Okra leaf trait into established cultivars. In the current study, we compared plant growth and fiber yield among near‐isogenic lines of Okra and normal selected from bulked heterozygous populations derived from two sets of contrasting crosses. Four paired near‐isogenic Okra leaf and normal leaf lines were planted in replicated trials on two planting dates in 1983 at Stoneville, MS Two strains had superior lint yield by the normal leaf sib while two others had superior lint yield by the Okras sib. ‘Stoneville 213’( STV 213), the Okra leaf cultivar produced by conventional backcrossing, served as the control wherein the normal leaf has been superior in yield compared to the Okra leaf. Except for plant height, the parameters of vegetative and reproductive growth showed no significant leaf type ✕ strain, or leaf type ✕ strain ✕ harvest date interactions. The Okra leaf entries produced maximal leaf area indices that were 26 and 49% smaller than those produced by the normal leaf entries for the April and May plantings, respectively. This disparity was partially offset by the production of more leaves by the Okra entries in the early planting, but not in the late planting. the number of squares and flowers produced by the Okra leaf entries indicates a greater fruiting potential than was realized. The percentage of bolls that was shed was closely associated with the maximal number of immature bolls produced. We concluded that the Okra leaf cottons can produce plant canopies competitive in yield with those of broad‐leaved cottons. The maximum potential of cottons with Okra leaves remains unclear, because of the large leaf type ✕ environment interactions.
Barley Composite Cross CC XXXV‐A as a Source for both Specific and Slow Rusting Resistance Against Leaf Rust1
Authors: Andres M. W. , Wilcoxson Roy D.
Published: July 2010

Whereas barley (Hordeum vulgare L.) cultivars grown in the northern Great Plains of the USA are susceptible to leaf rust, they could be improved by the use of either race specific or slow rusting types of resistance. The composite cross CC XXXV‐A was shown to be a source of both types of resistance. Plants from the composite cross were evaluated in the greenhouse and in the field for specific resistance (as indicated by infection types) and slow rusting resistance (as indicated by the area under the disease progress curve, AUDPC) to race 4 of the Puccinia hordei. Among 349 seedlings tested in the greenhouse, 73% exhibited specific resistance. Among 50 barley entries tested during 2 yrs in the field, entries with a high level of slow rusting resistance (small AUDPC 1) were found. Single plant evaluation for slow rusting resistance appeared to be a viable approach to rapid selection of desirable genotypes. The composite cross CC XXXV‐A contained many outstanding sources for both types of resistance and may be useful for breeding programs.
Direct and Correlated Response to Recurrent Full‐sib Selection for Prolificacy in Maize1
Authors: Singh Malkit , Khehra A. S. , Dhillon B. S.
Published: July 2010

Four cycles of full‐sib selection were conducted in ‘Partap’, an open‐pollinated cultivar of maize (Zea mays L.), for prolificacy separately under low and high plant density environments. The four cycles were completed in 2 yrs by staggered sowing of evaluation experiments and breeding nurseries. Selected populations, one each from low‐ and high‐density experiments, were developed after each selection cycle resulting in eight populations. These, along with the original Partap were evaluated in three environments with two N levels and four plant population densities. Linear response per cycle for number of ears per plant was significant and was greater in the low‐density selection environment (0.06 ears = 5.5%) than in the high‐density environment (0.04 ears = 3.6%). There was a significant correlated increase of 4.5% per cycle for grain yield. Significant correlated responses were observed for several other traits also. In general, ear girth of both series of populations and number of kernel rows of the populations developed in the low‐density environment increased, whereas plant height and days to silk in both series of populations, and ear length and height in populations developed in the high‐density environment decreased as a result of selection. Selection for prolificacy, therefore, may be useful in developing high yielding, early maturing, and short statured genotypes.
Heritability and Relationship to Yield of Excised‐Leaf Water Retention in Durum Wheat1
Authors: Clarke John M. , Townley‐Smith T. Fred
Published: July 2010

Previous research indicated that excised‐leaf water retention capability was related to drought resistance in Triticum spp., but no information is available on the heritability of the trait or its relationship to yield under drought conditions. The heritability and relationship to yield of excised‐leaf water retention capability was studied in eight durum wheat(T. turgidum L. var. durum)crosses involving the high retention parent ‘Pelissier’. Fifty random lines from each cross were studied under field conditions in the F4,F8 and F8 generations. Standard‐unit heritabilities of initial and initial minus wilted leaf water concentration were calculated by regressing F4 on F6, and F6 on F8 values. Heritability of initial leaf water concentration ranged from 0.08 to 0.61 in the F4/F6, and from 0.15 to 0.41 in the F6/F8 comparisons. Heritability of initial minus wilted water concentration ranged from 0.11 to 0.49 in the F4/F6 comparisons, and from 0.10 to 0.38 in the F6/F8. Simple correlations between yield and initial minus wilted leaf water concentration tended to be low and nonsignificant. Comparisons of the yields of the 10 fastest and 10 slowest water losers within crosses and years, however, showed significant differences in all but three of 20 cases. In two of the crosses, water retention was yield‐negative in low drought stress environments, but yield‐positive in a high‐stress environment. Retention capability tended to be yield‐positive or yield‐neutral in the other crosses regardless of environment. Further studies, using a broader range of genetics sources of high water retention, are required in order to develop suitable selection strategies for the retention trait.
Yield Component Analysis in Grain Sorghum1
Authors: Saeed Mohammad , Francis C. A. , Clegg M. D.
Published: July 2010

Environmental factors such as temperature and available moisture significantly affect the development of yield components in grain sorghum [Sorghum bicolor (L.) Moench]. However, effect of these factors may vary among plant growth stages. This study was conducted in the field to determine the relative importance of yield components and the effects of environmental factors in two growth periods, planting to bloom (Period 1) and bloom to physiological maturity (Period 2), on yield and its components in 46 sorghum hybrids tested in contrasting field environments. Number of seed was the major contributing component of yield, but the relative importance of seed weight to yield compared to number of seed increased from lownight‐temperature to high‐night‐temperature environments. Number of seeds head−1 was more important than number of heads in affecting variation in number of seed and yield among sorghum hybrids. Rate of grainfill day−1 accounted for more variation in seed weight than rate of fill per growing degree unit (GDU), but both were more important than the length of grainfill period. The relationship between the mean yield and the total GDU of environments was quadratic (R2=0.70), and GDU in the range of 1250 to 1350 favored development of high yields. Slow rate of GDU accumulation in Period 1 coupled with a relatively high rate in Period 2 was associated with high sorghum yields in high‐night‐temperature environments. In low‐night‐temperature environments, high GDU accumulation rate in both Period 1 and Period 2 favored high yields. Within an environment, the GDU accumulation rate was important to yield through its effects on seed weight. Although rain accounted for a significant proportion of variability in yield and its components in most environments, its effects generally were less important than those of GDU and GDU accumulation rate. The results indicate the importance of GDU and rate of GDU accumulation to yield and yield component development across diverse environments, and they demonstrate the need to exploit genetic variation of metabolic efficiency in grainfill in breeding programs designed for stress environments.