bluuebunny/crossref_metadata_2025 huggingface dataset:
Distance Statistics and Interpretation of Southern States Regional Soybean Tests
Authors: Hanson W. D.
Published: July 2010

The failure of genotypes to respond similarly to different environmental conditions, genotype environment (GXE) interaction, is an important aspect of genotypic stability. The objectives of this paper were to develop distances based on concepts of genotypic stability and to interpret regional soybean [Glycine max (L.) Merr.] tests based on these distances. Distances increased in relation to differential responses among sites for two genotypes or among genotypes for two sites. They were designed to evaluate the importance of region of origin in determining genotypic responses, the similarity of selections arising from different breeding programs, and the comparability of sites in regional testing. Seed yields for the Uniform Soybean Trials, Southern States, Maturity Groups V and VI, 1981–1991, were evaluated. Region of origin for genotypes did not have a major impact upon the nature of genotypic responses; however, genotypes from all regions showed less differential responses when tested at sites in the East Coast Region. The Group V selections from the North Carolina, Maryland, and Virginia breeding programs were more similar than selections from other breeding programs. Group VI selections from the Missouri program responded differently to environments than Group VI selections from other programs. The Plymouth, NC, Clemson, SC, and Athens, GA, test sites had similar relative seed yields among genotypes. A central belt of comparable sites extended from Virginia, North Carolina, South Carolina, and northeast Georgia to the mid and upper Delta Region. A northern belt of comparable sites covered Delaware, Maryland, western Virginia, Kentucky, upper Delta, and southeastern Kansas. The Tennessee sites were intermediate to these two belts. Sites in northwestern Georgia and northern Alabama and the remaining sites in the southern tier of states gave heterogeneous genotypic responses. Comparable sites that represent areas within this region were not found. Genotypes with unique local adaptations would be required.
A Shifted Multiplicative Model Fusion Method for Grouping Environments without Cultivar Rank Change
Authors: Crossa José , Cornelius Paul L. , Sayre Ken , Ortiz‐Monasterio R.J. Iván
Published: July 2010

Genotype × environment interactions of most concern to plant breeders involve cultivar rank change across environments, i.e., crossover interaction (COl). When COls are present, cluster strategies can be used to group environments without significant changes in cultivar ranks. Several methods for classifying environments without COI have recently been proposed. In this study, the shifted multiplicative model (SHMM) fusion method based on a building block principle is used for grouping environments which rank cultivars similarly. The SHMM fusion selects the best action by computing for each new cluster formed, a new set of distance measures with the other clusters and with the unclustered individuals. Experimental data were collected on 55 cultivars evaluated under five irrigation levels in each of two trials (I0 environments). Groups of environments obtained with SHMM fusion were compared with those obtained using cluster analysis based on Euclidean distances computed from unstandardized and standardized data. The SHMM fusion formed four final clusters of environments. The final clusters grouped environments with similar irrigation levels. Conventional cluster analysis based on Euclidean distances produced final clusters with much larger percentage of COls than SHMM fusion. Results show that SHMM fusion is a useful strategy for classifying environments without cultivar rank change.
Clover Management to Provide Optimum Nitrogen and Soil Water Conservation
Authors: Harper L. A. , Hendrix P. F. , Langdale G. W. , Coleman D. C.
Published: July 2010

Legumes are commonly used to provide nitrogen (N) for succeeding crops, but the net gain in N to the system is rarely measured. This study developed a N budget for a winter legume production system to estimate sources, sinks, and net system gain in N. Crimson clover (Trifolium incarnatum L.) reseeded from the preceding year and was killed with herbicide the following spring. A forage sorghum crop (Sorghum vulgare Pers.) was planted and harvested twice during the summer. Subplots were sampled at frequent intervals throughout the growing seasons for measurements of plant biomass and N content (leaves, steins, seeds, roots, and litter) and soil mineral N. During the clover growing season, soil N mineralization and leaching rates were estimated with an in situ chamber technique, and aerial ammonia (NH3) transport measurements were made biweekly by micrometeorological techniques. Nitrogen in the clover crop increased until anthesis, and then declined slightly prior to desiccation with herbicides. Total N accumulated in the clover at desiccation was 323 kg N ha−1 (28 in leaves, 81 in stems, 40 in seeds, 44 in surface‐layer roots, and 130 in dead leaves and litter). Aerial NH3 absorption by the clover was small during the growing season (0.18 kg N ha−1) but NH3 loss from the killed clover was also minimal (0.25 kg N ha−1) and occurred during the period shortly after herbicide application. The summer sorghum crop took up 454 kg N ha−1 over the course of two cuttings from the soil mineral and mineralized organic N resource plus atmospheric NHj and other atmospheric N inputs such as wet and dry deposition. Total N accumulated by the clover from N fixation, soil mineral N uptake, and NH3 absorption provided the equivalent of 70% of N removed by the sorghum crop.
Karyotype of Cuphea lanceolata Ait. and Cuphea viscosissima Jacq.
Authors: Chen Weiping , Roath W. W.
Published: July 2010

Cuphea lanceolata Alton and C. viscosissima Jacq. are potential germplasm sources of medium‐chain fatty acids. The fertile hybrid between these two species is being used to develop unproved cultivars as a domestic source of these important oils. A total of 1401 Giemsa C‐banded chromosomes from 145 root‐tip cells of these two species are karyotyped with the assistance of computer imaging techniques. Karyotype was defined by measuring individual chromosomes, computing the relative chromosome length and arm ratios, and identifying specific heterochromatic and euchromatic regions of individual chromosomes. The karyotype of these two species (2n = 12) consists of one pair of satellited chromosomes, two pairs of metacentric chromosomes, and two pairs of submetacentric chromosomes. Chromosome 2 is submetacentric in C. viscosissima but metacentric in C. lanceolata. The differences in relative chromosome length between homologous chromosomes of C. viscosissima and C. lanceolata were not significant. Karyotype asymmetry indices are the numerical expression for the general morphology of plant karyotypes. The intrachromosomal asymmetry index is 0.43 and 0.47 and the interchromosomal asymmetry index is 0.25 and 0.26 for C. lanceolata and C. viscosissima, respectively. The similarity of homologous chromosomes and C‐banding patterns indicate a close phylogenetic relationship between C. viscosissima and C. lanceolata.
Introduction of Quarantined Seed for Crop Science Registration
Authors: White G. A.
Published: July 2010

Registration of germplasms cultivars, parental lines, and genetic stocks in Crop Science provides recognition to scientists that develop and document these plant materials. During 1987 through 1993, 8.5% of Crop Science registrations were of foreign origin. Among the ese, 26% were quarantine‐restricted. The purpose of this report is to provide guidelines to foreign contributors of quarantined plant germplasm for Crop Science registration. Seeds of several crop genera from other countries that might be registered are in the prohibited quarantine category and can be introduced only under permit. Examples include the crop genera Arachis, Gossypium, Oryza, Pennisetura, Sorghum, Triticum, and Zea. Send samples of clean, untreated seeds and associated information to the USDAP lant GermplasmI nspection Station, Bldg. 580, BARC‐East, Beltsville, MD 20705. The number of seeds needed for quarantined‐growouts will vary depending on the class of registration. Procedures described herein generally apply to quarantined introductions for purposes other than Crop Science registration.
Additional Sources of Stem Canker Resistance in Soybean Plant Introductions
Authors: Tyler Jeff M.
Published: July 2010

Stem canker caused by Diaporthe phaseolorum (Cooke & Ellis) Sacc. f. sp. meridionalis Morgan‐Jones can cause significant yield losses in soybean [Glycine max (L.) Merr.] in the southern USA. Many genotypes are known to be resistant to the disease; however, little is known about the inheritance of resistance and allelic relationships of genes conferring resistance. The objective of this study was to determine the inheritance of resistance in two germplasm accessions, PI 230976 and PI 398469, and define allelic relationships with the four described genes. Each PI was crossed with a susceptible genotype, J77‐339, and the four fines carrying Rdcl, Rdc2, Rdc3, or Rdc4. Crosses were made in the field at Stoneville, MS, in 1992, and F1 backcrosses to J77‐339 were made in 1993. Plants of parents and 10 F2 populations were toothpick inoculated in the field in 1993. The F2:3 and backcross populations were later evaluated in a greenhouse. The F2 populations derived from J77‐339 × PI 230976 and J77‐339 × PI 398469 approached a 3 resistant/1 susceptible ratio indicating that a single dominant gene for resistance is carried by each plant introduction. The F3 data confirmed this result. Backcross data substantiated complete dominance. Response of all F2 populations derived from crosses with genotypes carrying known genes suggested a 15:1 ratio indicating nonallelism. It is not known if both plant introductions carry the same gene. These sources of resistance may lessen genetic vulnerability should new virulent isolates overcome sources now used by breeders
Powdery Mildew Resistance in Winter Wheat: I. Gene Number and Mode of Inheritance
Authors: Chung Y. S. , Griffey C. A.
Published: July 2010

Few widely effective sources of resistance to powdery mildew, caused by Blumeria graminis (DC.) E. O. Speer f. sp. tritici Em. Marchal, have been identified in wheat (Triticum aestivum L.), and the identity of resistance genes in many cultivars is unknown. Ten winter wheat lines selected from the 1982 International Winter Wheat Mildew and Rust Nurseries were studied to characterize gene number and mode of inheritance of resistance to powdery mildew. Each of the lines were crossed to the susceptible cultivar Chancellor. Seedlings of the parental lines, F1, F2, BC1 (Chancellor × F1), and F3 populations were inoculated with isolate 127 of B. graminis in the greenhouse and evaluated for powdery mildew reaction. All parents were resistant, except for ST1‐25, which had an intermediate reaction type. Genetic analyses revealed that resistance in C39 and SI5 is conferred by three dominant genes, and resistance in A55‐2, R107, GO4779, OK75R3645, and Bulk PV63‐6 is governed by single partially dominant genes. Data from F2, F3, and BC1 populations, derived from crosses between ‘Armada’ and Chancellor, were inconsistent but indicated that Armada has at least one dominant gene for resistance, which likely is Pm4b us previously postulated. Resistance in VPM1 and ST1‐25 is governed by one recessive gene in each fine. Three to 11 different resistance genes are represented among the 10 parents.
Agronomic Performance of Soybean Recombinant Inbreds in Northern USA and Chile
Authors: Mansur L. M. , Orf J. H.
Published: July 2010

Winter nurseries are widely used by soybean [Glycine max (L.) Merr.] breeders for generation advancement. Limited research has shown that off‐season facilities can also be used to select for agronomic traits. Our objective was to determine the relationship in performance between soybeans grown in northern USA and those in central Chile for days to maturity (RS), plant height, lodging, seed protein and oil concentration, and seed weight and yield. For this purpose, 284 recombinant inbred lines of soybean (RIL) ranging from Maturity Group 00 to I, their parents, ‘Minsoy’ and ‘Noir 1’, and 10 check cultivars were evaluated in Minnesota, USA, and central Chile during 2 yr using a randomized complete‐block design with three replications. There were highly significant differences among RILs for all traits. Estimates of heritability (h2) on an entry mean in the USA ranged from 0.65 for protein concentration to 0.89 for R8 and plant height, whereas in Chile they ranged from 0.74 for oil concentration to 0.93 for plant height. Across countries, h2 ranged from 0.69 for oil concentration to 0.93 for plant height. Moreover, the phenotypic (and rank) correlations for performance between central Chile and northern USA were high, positive, and highly significant (P < 0.01): 0.89 (0.90), 0.89 (0.90), 0.79 (0.85), 0.68 (0.62), 0.67 (0.62), 0.78 (0.80), (0.70) for R8, plant height, lodging, seed protein and oil concentration, and seed weight and yield, respectively. The same correlations for the 10 check cultivars confirmed these results. We concluded that selection for these traits in off‐season winter nurseries in central Chile should also be effective in identifying genotypes that perform similarly in the northern USA.
Phenotypic Recurrent Selection for Increased Endosperm Hardness in Two High‐Lysine Maize Synthetics
Authors: Lambert R. J. , Chung Ling‐chen
Published: July 2010

The agronomic problems associated with high lysine opaque‐2 maize (Zea mays L.) could be eliminated with the development of opaque‐2 genotypes with harder endosperm texture. Two opaque‐2 maize synthetics Illinois Disease Oil Opaque‐2 and Illinois Elite Single Cross Opaque‐2 were selected for increased endosperm modification or kernel hardness. Phenotypic recurrent selection was used to select for increased endosperm modification for five cycles. Seed from 200 individual selfed plants in each synthetic was evaluated for endosperm modification each cycle, and seed from 40 plants with the highest endosperm modification were intermated to produce the next cycle of selection. Progeny representing each of the five cycles of each synthetic were evaluated for 2 yr (1991–1992) in replicated field experiments at Urbana, IL. A split plot experiment, using a randomized complete block design, with synthetics as main plots and cycles as sub‐plots, was used to evaluate selection response. Traits evaluated were endosperm modification, grain yield and moisture, 100‐kernel‐weight, plant height, oil, protein, starch, lysine content, and lysine/protein ratio. Five cycles of selection showed a significant increase in endosperm modification, Disease Oil Opaque‐2 showing a 42% increase and Elite Single Cross Opaque‐2 a 31% increase. Significant cycle effects were observed for protein and starch content. Significant years × cycles and years × synthetics × cycles interactions were observed for several traits but were all of the non‐crossover type. No changes in the nutritional characteristics of both synthetics were observed as a result of selection for increased endosperm modification. The results were obtained without monitoring lysine or tryptophan during selection. Results indicate Corn Belt adapted opaque‐2 synthetics with a high degree of endosperm modification can be developed with appropriate selection procedures
Root Cytokinin Level in Relation to Heat Tolerance of Phaseolus acutifolius and Phaseolus vulgaris
Authors: Udomprasert Nawarat , Li Paul H. , Davis David W. , Markhart Albert H.
Published: July 2010

Heat stress influences plant growth and crop production. This research was conducted to determine the importance of root cytokinin level in plant heat tolerance. Tepary bean (Phaseolus acutifolius Gray) and heat tolerant (GNUI 59) and heat sensitive (BBL 47) genotypes of common bean (P. vulgaris L.) were used to determine root and leaf cytokinin levels under 45°C air temperature and either 45 or 25°C root temperature. The concentrations of root zeatin riboside (ZR) were about two‐ to three‐fold higher in tepary bean and GNUI 59 than in BBL 47 under all conditions. Root isopentenyl adenosine ([9R]iP) was much lower than root ZR. High shoot/root temperature (45/45°C) for 5 reduced the root ZR and [gR]iP concentrations in all three genotypes. Heat treatments did not alter leaf ZR and [9R]iP. Pretreatment with exogenous ZR (1 μM) did not show any alleviation from heat injury in terms of photosynthetic activity, even though endogenous ZR levels increased, compared with those without ZR pretreatment. Reciprocal grafting of BBL 47 shoots on tepary roots increased leaf ZR level at high temperature but did not increase photosynthetic activity. Results suggest that root ZR level is not important in determining plant heat tolerance.
Isozyme Variation in Avena sterilis L. Collected in Turkey
Authors: Hunter D. E. , Murphy J. P. , Phillips T. D.
Published: July 2010

The National Small Grains (NSG) collection of Avena sterilis L. is an important germplasm resource for cultivated oat (A. sativa L. and A. byzantina C. Koch) improvement. Complete evaluation and utilization of the almost 7000 accessions will be protracted. In the interim, new accessions will be acquired. Previous studies showed that Turkish accessions of A. sterilis exhibited a broad array of isozyme phenotypes found in the wild collection and in over 400 cultivated accessions. The objectives of this research were (i) to determine if recent Turkish acquisitions of A. sterilis (Forsberg‐Simons collections of 1986) have contributed additional isozyme variation to that already in storage and (ii) to illustrate relationships among Turkish A. sterilis and cultivated germplasm. Zymogram phenotypes of 341 A. sterilis and 405 cultivated samples were recorded for 13 enzyme systems. The ll5‐plant sample from the Forsberg‐Simons collection included six phenotypes not previously observed in Turkish accessions in the NSG collection. Cluster analysis suggested that approximately 40% of the Forsberg‐Simons acquisitions differed from much of the existing NSG Turkish accessions. Both local and regional diversity occurred within A. sterilis germplasm. Isozyme patterns in cultivated germplasm were most similar to collections of A. sterilis with a wide geographical distribution.
Characteristics of the Elite Population Selected on Ratio Criterion: II. Traits with Unequal Genetic Variances
Authors: Rowe D. E.
Published: July 2010

Individuals of a population can be selected simultaneously for two positively valued metric traits X and Y based on their ratio (X/Y) the ratio criterion (RC). The ratio calculation is simple and sometimes has an intrinsic biological or economic significance. In this simulation study, the traits X and Y have normal distributions, genetic variances summing to 2, 3, or 5, and ratios of genetic variances of numerator to denominator traits that are 4:1, 2:1, 1:1, 1:2, and 1:4. As in an earlier study, responses to RC selection were simulated for genetic correlations between traits X and Y of − 0.75, −0.50, −0.25, 0.0, 0.25, 0.50, and 0.75. For genetic correlations of −0.75, −0.50, −0.25, 0.0, and 0.25, the RC selection caused one trait to increase in value while the second decreased for each ratio of variances. for highly positive genetic correlations of 0.50 and 0.75, the ratios of genetic variances had differential qualitative effects on the responses. Depending on the ratios and whether selection was for an increase or decrease in the ratio, the means of traits X and Y may both increase or both decrease or one may change while the second is unchanged. With RC selection, the effects on component traits X and Y may be undesirable. It is suggested that in the presence of any positive genetic correlation, RC selection should be executed with care.
Correcting for Inbreeding in Parent‐Offspring Regression Estimates of Heritability with Non‐Additive and Genotype × Environment Effects Present
Authors: Gibson P. T.
Published: July 2010

Inbreeding, non‐additive genetic effects, and genotype × environment interactions (G×E) cause parent‐offspring (PO) regression estimates (b) of heritability obtained from one pair of PO generations differ from those obtained from another pair of generations. If no non‐additive genetic effects and no G×E are present, the influence of inbreeding is removed by the correction of Nyquist, h2 = b = b/[1 + Ft(1 − b)], where Ft is the inbreeding coefficient in the generation line derivation (t). When b is near unity, the correction is small even with complete inbreeding. However, h2 is only slightly more than 0.5 b when b is small and Ft ≥ 0.5 (any generation greater than F2 or S0 in a selling series). This paper assesses the biases from use of Nyquist's correction with G×E, and with non‐additive genetic effects with and without G×E. When considering individual‐plant heritabilities, values of b′ were compared with b001, defined as the parent‐offspring regression coefficient of S1 on S0 (or F3 on F2). In the absence of G×E, gene frequencies of 0.5 result in b′ values within 0.1 absolute unit of b001, regardless of non‐additive effects or degree of inbreeding. Gene frequencies in the range of 0.1 to 0.9 combined with additive epistasis, but with no dominance, produce no severe biases, arbitrarily defined as |b′ − b001| ≥ 0.1 and (|b′ − b001|/b001) ≥ 0.2 occurring jointly. Dominance, with or without additive epistasis, occasionally produces severely biased values of b′, which generally overestimate b001 more strongly as inbreeding increases. Non‐additive effects combined with G×E produce b′ values that sometimes severely underestimate b001, especially as inbreeding increases. Overall conclusions were the same for family‐mean heritabilities in which b′ was compared to b012, defined as S2 on S1 family mean (or F4 on F3) regression. Despite some cases of severe bias, b′ is generally superior to b per se as an estimator of b001 or b012.
A PCR‐Based Screening Assay of Ph1, the Chromosome Pairing Regulator Gene of Wheat
Authors: Gill Kulvinder S. , Gill Bikram S.
Published: July 2010

Ph1 is the principle gene regulating chromosome pairing of wheat (Triticum aestivum L. em Theli.). Ph1 dictates that only the homologous (not homoeologous) chromosomes can pair at MI of meiosis. In the absence of the gene, homoeologous chromosomes may also pair, however. Homoeologous chromosome pairing can be activated by temporarily replacing the normal copy of the gene with its null allele, which is present in the ph1b mutant. One of the main difficulties during these manipulations is the scoring plants for the presence or absence of the Ph1 gene. We developed a polymerase chain reaction (PCR) based screening assay for the Ph1 gene. The probe pHvksu8, which maps in the interstitial deletion of the ph1b mutant encompassing the Ph1 gene, was sequenced and forward and a reverse primers, 20 bp each, were generated. These primers amplified a fragment each for chromosomes 5A, 5B, and 5D. The 5B specific fragment was not amplified in the ph1b mutant, and can be used as a diagnostic fragment to score plants for the presence of Ph1 gene. The reliability of the primers for the Ph1 gene scoring was tested on an F2 population of 40 plants, segregating for the Ph1 gene. No discrepancy was observed between the PCR‐based assay and gel blot DNA hybridization for detection of the fragment associated with the Ph1 gene.
Soybean Response to Sudden Death Syndrome: Inheritance Influenced by Cyst Nematode Resistance in Pyramid × Douglas Progenies
Authors: Njiti V. N. , Shenaut M. A. , Suttner R. J. , Schmidt M. E. , Gibson P. T.
Published: July 2010

To determine the inheritance of soybean [Glycine max (L.) Merr.J response to sudden death syndrome (SDS), 90 F6‐derived lines from the cross of ‘Pyramid’ × ‘Douglas’ were tested in field conditions in two replications of each of six southern Illinois environments naturally infested with the SDS pathogen Fusarium solani (Mart.) Appel & Wollenw. emend. Snyd. & Hans. Lines were rated for disease incidence (DI, 0–100%), disease severity (DS, 1–9), and the reproductive growth stage (R). The DI and DS were standardized to the full pod (R6) growth stage. Disease index was calculated as DI × DS/9, with a possible range of 0 (no disease) to 100 (all plants dead). Lines were also characterized in the greenhouse as resistant or susceptible to soybean cyst nematode (SCN; Heterodera glycines Ichinohe) Races 3 and 14. The group of SCN resistant lines was significantly less susceptible to SDS than the SCN susceptible group in three of the six environments. In Pulaski 1991, lines with SCN Race 3 and 14 resistance were significantly more susceptible to SDS on average than the SCN susceptible lines and than the lines with SCN Race 3 resistance only. Multigenic inheritance was implicated because the frequency distributions of SDS response were continuous with a large range (8–12 times the standard error of a line mean) in all environments and were unimodal in all but one environment. On the basis of line means, heritability estimates within environment ranged from 0.68 to 0.83 and across environments were 0.75, indicating that soybean response to SDS is highly heritable. There was a significant genotype × environment interaction in these lines emphasizing the need for multiple‐environment testing for effective selection of stable resistance to SDS.
Genetic Gain in Soybean Populations with Different Percentages of Plant Introduction Parentage
Authors: Ininda Jane , Fehr Walter R. , Cianzio Silvia R. , Schnebly Steven R.
Published: July 2010

Plant introductions (PIs) can be used to increase the genetic diversity of soybean [Glycine max (L.) Merr.] populations. A recurrent selection program was initiated to determine if populations with PI parentage would exhibit greater genetic gain for seed yield than a population with no PI parentage. The objective of our study was to evaluate the genetic gain for seed yield and correlated responses in maturity and lodging from three cycles of recurrent selection in five soybean populations, AP10 to AP14, formed with different percentages of PI parentage. The percentages of PI parentage were 100% in AP10, 75% in AP11, 50% in AP12, 25% in AP13, and 0% in AP14. In each cycle, 200 F4‐derived lines for each population were evaluated and the 20 highest yielding lines were chosen as parents for the next cycle. For our study, the 20 parents of Cycles 1, 2, and 3 were grown in a randomized complete‐block design at three Iowa locations. There was a significant (P < 0.01) linear increase in seed yield for all populations across the three cycles. The gain from selection for seed yield was 153 kg ha−1 (5.4%) cycle−1 for AP14, 80 (2.8%) for AP13, 85 (3.1%) for AP12, 54 (2.0%) for AP11, and 66 (2.5%) for AP10. AP14 had the highest mean yield of the parents of each cycle and the highest yielding parent of each cycle. A significant linear increase in mean days to maturity was observed in all populations, except AP13. Lodging scores exhibited a significant linear decrease in AP10 and AP13, but no significant response was observed in the other three populations. The results indicated that after three cycles of selection, Pis used to form AP10 to AP13 did not increase genetic gain for seed yield compared with AP14 that was developed from only adapted cultivars and experimental lines.
Inheritance of Resistance to the Soybean Looper in Soybean
Authors: Kenty Michael M. , Hinson Kuell , Quesenberry Kenneth H. , Wofford David S.
Published: July 2010

Phytophagous insects cause significant economic damage to soybean [Glycine max (L.) Merr.] throughout the southern USA, but soybean plant breeders have the option of utilizing insect resistant germplasm. This study was conducted to determine the inheritance of resistance to the soybean looper [Pseudoplusia includens Walker] in soybean. The insect‐resistant breeding line D86‐3429 and the more susceptible cultivar Braxton were used to produce the F1, F2, BC, and BCS populations necessary to conduct the genetic studies. Defoliation occurring in 0.068‐ha field cages in 1990 and 1991 from insect releases was estimated by the whole plant visual rating method in 1990 and the partitioned plant average visual method in 1991. The data from the preliminary study in 1990 showed a trend towards quantitative inheritance, therefore the 1991 data were analyzed quantitatively. Mather's scaling test was applied to the data generated from each of two cages, and the results indicated that generation means depend only on additive gene effects. Utilizing Hayman's methodology in the generation means analysis, an epistatic effect was suggested but the primary effect is assumed to be additive as was indicated in the scaling test. Estimates of gene numbers indicate that the two parents differed by two genes for resistance to soybean looper. Heritability for resistance was estimated to be 63%; therefore, a breeder should be able to make progress by selecting in the F2 or F3 generations.
Evaluation of Populations for Their Potential to Improve Three Maize Hybrids
Authors: Dudley J. W. , Lamkey K. R. , Geadelmann J. L.
Published: July 2010

Identification of sources of favorable alleles to improve existing hybrids is one of the most important problems facing a maize (Zea mays L.) breeder. Previous work has demonstrated the effectiveness of a procedure developed by Dudley for identifying populations containing favorable alleles not present in an elite hybrid. However, previously reported work involved at most two elite hybrids. The objective of this study was to evaluate the potential of 20 improved populations to improve the three hybrids made from three inbreds in commercial use. Each of the populations was crossed to LH195, LH212, and LH216. The population × inbred crosses, the three hybrids among the inbreds, and the three inbreds were evaluated in seven U.S. midwestern environments in 1993 and four in 1994. Traits measured were grain yield, grain moisture, plant height, ear height, and concentration of protein, oil, and starch in the grain. For grain yield, 15 of the 20 populations had significant estimates of dominant favorable alleles not present in the highest yielding target hybrid (LH195 × LH212). None of the populations showed potential for reducing ear height. However, seven populations had more favorable recessive alleles than unfavorable dominants for plant height when LH195 × LH212 was the target hybrid. None of the populations tested appeared to have potential for increasing starch concentration in any of the target hybrids. Eight populations showed potential for increasing protein concentration in all three target hybrids. Assumptions required to identify parents were not met for grain moisture, oil concentration, and stalk and root lodging.
Correlated Responses in Ear and Plant Traits in Maize Synthetics Selected for R‐nj Color Expression
Authors: Nguetta A. S. P. , Cross H. Z.
Published: July 2010

Maize (Zea mays L.) cobs contain vascular tissue that supports grain yield. We wanted to learn if rate of grain filling or carbohydrate source (leaf area) are related to early ear and cob development. studied substrains (known to differ in grain‐filling rates) derived from two early‐ (NDSF, NDSM), two intermediate‐ (NDSC, NDSD), one late‐maturing (NDSE) synthetics. These five synthetics were each mass selected for four cycles for high (HC), random (RC), and (LC) R‐nj color expression. Plants of each of the 15 substrains were grown in the field at 58 000 plants ha−1 in Fargo and Casselton, ND, in 1993 and 1994. We measured leaf lengths, widths, and numbers to estimate leaf areas per plant. We monitored early ear development for two maturity groups within each substrain by measuring ear lengths, widths, and wet weights at 7 and 14 d after silking. Maturity differences among synthetics explained more than 80% of the variation in leaf length and width, leaf area per plant, and ear length at 7 d. The HC, compared with LC, selections produced 3% longer and 6% heavier ears at 7 d, had 5% more and 3% wider leaves, and had 4% larger leaf areas per plant. The earlier ear development of HC strains may contribute to higher kernel growth rates. Due to larger leaf areas per plant, HC strains also may produce more photosynthate for translocation into the developing kernels. Selecting for improved vascular systems may be useful.
Softening and Loss of Subterranean Clover Hard Seed under Sod and Bare Ground Environments
Authors: Fairbrother T. E.
Published: July 2010

Natural reseeding of subterranean clover (Trifolium subterraneum L.) grown with a warm‐season grass in the southern USA depends on the proper softening rate of hard seed. Three experiments were each conducted over 2 yr to determine (i) the rate of seed softening, (ii) the cause of reduction in seed softening over time, and (iii) the effect of clipping management on seed softening. In all experiments, subterranean clover hard seed were placed in dacron bags and buried 1 cm deep in field plots. In Exp. 1, bags were placed in bermudagrass [(Cynodon dactylon (L.) Pers.] sod and in bare ground in July and sampled over the summer and fall. In Exp. 2, bags were placed in soil and bare ground and replaced with separate samples at intervals of 28 d throughout the summer and fall. In Exp. 3, bags were buried in bare ground or sod that was clipped monthly to 7.5 cm or biweekly to 2 cm starting in August, September, or October. Hard seed softened more rapidly in bare ground than in sod, reaching a minimum of 15.6 and 49.0%, respectively. The softening of hard seed over 28‐d intervals decreased from 75.5 and 67.1% in July to 92.6 and 93.2% in November for sod and bare ground, respectively. Fall clipping management had no effect on hard seed softening rate of subterranean clover, reaching a minimum of 64.0% hard seed averaged over all sod clipping treatments compared to 47.0% hard seed for bare ground. Results indicated that subterranean clover reseeding ability should be evaluated under the same environment as the clover is used.
Variation in Mineral Concentration and Grass Tetany Potential among Russian Wildrye Accessions
Authors: Jefferson P.G. , Mayland H.F. , Asay K.H. , Berdahl J.D.
Published: July 2010

Grass tetany or hypomagnesemic tetany in cattle (Bos taurus) is caused by an imbalance of K, Ca, and Mg in the diet. Indications of grass tetany range from reduced milk yield or weight gain to severe convulsions and death. The risk of grass tetany dramatically increases when the K/(Mg + Ca) ratio of forage exceeds 2.2, especially for dams during early lactation. Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], a valuable forage species, has ratios well above this level. Our objectives were to determine the mineral concentration and ratio values for 65 accessions of Russian wildrye to select germplasm sources with low tetany ratio and to determine the effects of year, location, and their interactions with accessions. Seedlings of each accession and two checks, Syn A and Mankota, were established in replicated space‐plant nurseries at Logan, UT, Mandan, ND, and Swift Current, Saskatchewan, Canada. Years‐within‐location effects generally produced the largest variance component, while the accession variance was larger than location × accession and location × accession × year interaction variances for K, Ca, Mg, K/(Mg + Ca) ratio, and Reduced Tetany Potential (RTP) index. Selection for these traits in Russian wildrye germplasm will require multiple years to characterize adequately accessions, breeding lines, or synthetics. The K/(Ca + Mg) ratio of the accessions tested ranged from 2.2 to 3.0 when averaged across sites and years for V4 growth stage. A similar range of ratio values and ranking of the accessions was observed at the E2 growth stage. The three tetraploid accessions evaluated were among the five accessions with the highest tetany ratios. Previously reported forage yield and seed yield means were significantly correlated with K, Mg, and N concentrations and K/(Ca + Mg) ratio. The RTP index was not correlated with forage yield, seed yield, or N concentration. Therefore, selection in Russian wildrye should be based on increased RTP index rather than K concentration or K/(Ca + Mg) ratio to avoid concomitant unintentional selection of reduced forage yield and seed yield.
Multipurpose Cryogenic Surface Apparatus: A Liquid Nitrogen‐Chilled Sample Tray
Authors: Adam N.R. , Wall G.W.
Published: July 2010

The use of cryogenic techniques allows collection and storage of large numbers of samples for later processing for biochemical assays. In large field studies it is very difficult to obtain an accurate measure of leaf area as the samples are collected while preserving biological activity. Measurement of leaf area at the time of processing is also difficult because thawing of leaf tissue can cause degradation of leaf biochemical components and processes. The objective of this study was to design a liquid N2–chilled tray that allows cryogenically preserved samples to be sorted and measured without the risk of sample thawing. A stainless steel lid (working surface) was brazed to a stainless steel pan, creating a reservoir that could be filled with liquid N2 The working surface could then be maintained at approximately the temperature of liquid N2 Enzyme activities and polyacrylamide gel separations of ribulose‐1,5‐bisphosphate carboxylase (Rubisco) and phosphoenol pyruvate carboxylas (PEPCase) of sorghum [Sorghum bicolor (L.) Moench] were used to assess the performance of the tray. Enzyme activity assays and gel separations of Rubisco and PEPCase confirm that biological activity is maintained through use of the multipurpose cryogenic surface (MCS) tray.
Estimation of Fall Dormancy in Alfalfa by Near Infrared Reflectance Spectroscopy
Authors: Kallenbach R.L. , Roberts C.A. , Teuber L.R. , Bishop‐Hurley G.J. , Benedict H.R.
Published: July 2010

Estimating fall dormancy (FD) in alfalfa (Medicago sativa L.) is time‐consuming and expensive. The objective of this study was to estimate the FD class of alfalfa using near infrared reflectance (NIR) spectroscopy. Eleven alfalfa cultivars ranging in FD from 1 to 11 were grown as spaced plants at four diverse locations. In early autumn, 55 to 65 plants were randomly selected at each location and FD determined for each plant. For each sample, NIR spectra were collected and FD values regressed against first and second derivative transformations of spectra by modified partial least squares regression. The optimum equation had a calibration R2 of 0.90 and a mean and standard error of 7.93 ± 1.14. Blind validation samples showed that this equation could accurately predict the FD class of individual plants (r2 = 0.85) as well as entire cultivars (r2 = 0.94). We concluded NIR spectroscopy has the potential to estimate FD classes of alfalfa.
Improved Rotary Sieve for Measuring State and Stability of Dry Soil Structure
Authors: Chepil W. S.
Published: July 2010

An improved rotary sieve designed to overcome the limitations of the original sieve (1) was constructed and thoroughly tested.

The improved apparatus is capable of separating dry soil in one operation into any number of dry soil fractions up to 14. The operation requires little technical skill. The results of sieving are independent of personal judgment.

The apparatus was found useful for determining the relative mechanical stability as well as the state of aggregation of soil in a dry condition. Mechanical stability, as determined from the relative resistance of soil aggregates to breakdown by repeated sieving, varied directly with the resistance of the soil aggregates to abrasion by wind‐blown soil materials. Abrasion is one of the serious aspects of erosion of soil by wind.

The rate of breakdown of soil aggregates varied exponentially with the number of sievings. Assuming this type of relationship to extend beyond the experimental range, the amounts of some particular size of aggregates present in soils before sieving were estimated.
Zonal Soils in the Transition Region between the Podzol and Gray‐Brown Podzolic Regions in Michigan
Authors: Gardner D. R. , Whiteside E. P.
Published: July 2010

Studies were made of soil profiles from an area in central Michigan lying along the Podzol‐Gray‐Brown Podzolic transition region. The profiles are grouped in a lithosequence of seven textures from sand to silty clay loam and reproduced photographically. Selected physical and chemical analyses from three of the seven textures are presented tabularly.

Through the range of textures studied, these profiles possess a common sequence of horizons. While the surface horizons are clearly those of a Podzol, they are underlain by what appear to be the A2 and B2 of a Gray‐Brown Podzolic profile. The influence of the texture of parent material is such that, in the sandier types, the upper Podzol is much more strongly developed than is the lower Gray‐Brown Podzolic profile while in the heavier textures, the reverse is true.

The authors conclude that these double profiles represent the zonal soil for this area and are correlatives of the double profiles described by other workers in New York and in Ontario. These soils are neither true Podzols nor true Gray‐Brown Podzolic soils but exhibit the characteristics of both groups, the affinity for one or the other being related to the texture of the parent materials.
Depth to Plow Pan as a Factor in Sugar Cane Production
Authors: Scarsbrook C. E. , DeMent Jack D. , Sturgis M. B.
Published: July 2010

Results from fertilizer studies in the sugar cane growing areas of Louisiana have shown no consistent relationship between native soil fertility as determined by soil tests and yields of sugar cane. In many cases there have been very low responses to the fertilizers. This investigation was made to determine what soil factors were related to yields. Measurements of depth to plow pan, aggregation, organic matter, soluble phosphorus, and exchangeable cations were made on check plots and plots receiving the highest rates of fertilizer.

Depth to plow pan was directly related to yield on unfertilized plots. There appeared to be a trend toward greater increases in yield due to added fertilizer as the depth to the plow pan decreased. Except in extreme cases other factors measured had less effect on yields.
Further Studies on the Effect of Long‐time Organic Matter Additions on the Physical Properties of Sassafras Silt Loam
Authors: Russell M. B. , Klute A. , Jacob W. C.
Published: July 2010

The objectives of the investigation were to determine the effects of long‐time differential manure applications on physical properties, organic matter, and nitrogen content; to provide a “bench‐mark” for future studies on the permanence of the observed differences following the discontinuance of the treatments; and to study the distribution of variance among the experimental, sampling, and determination error terms as a guide for planning future studies involving the same plots and measurements.

Composited soil samples were taken at three depths from plots representing three replications of each of four treatments. Organic carbon, total nitrogen, moisture equivalent, 15‐atmosphere percentage, aggregate stability, and percent sand were determined on all samples. Proctor compaction and penetrability measurements also were made.

Twenty‐five annual applications of manure at rates of 0, 10, 20, and 40 tons per acre have resulted in highly significant differences in organic carbon and nitrogen percentages, aggregate stability, and susceptibility to compaction of Sassafras silt loam. Highly significant positive correlation coefficients were obtained between the organic matter content and the moisture equivalent, 15‐atmosphere percentage, and aggregate stability. Sampling and determination variances were in general well below the corresponding experimental variances.
Colloidal Properties of Soils from Western Equatorial South America
Authors: Miller E. V. , Coleman N. T.
Published: July 2010

Equatorial soils of Ecuador and Peru were studied by chemical, differential thermal, and X‐ray spectrographic methods of analysis with the aim of clarifying their classification and fertility properties.

A classification key permits the presentation of the soils and their properties according to major soil groups.

In the humid tropical regions kaolin clays are common, but there is also evidence of juvenile soils. Immaturity is indicated by high contents of exchangeable bases, presence of clays with high cation exchange capacities, evident lack of crystallinity of the clays, and pH values which are relatively low for the existing degree of base saturation.

Dark colored acidic Andean soils possess high phosphate retaining capacities and high exchangeable aluminum. Their C/A capacity ratios are less than 1.

Soils of the drier equatorial regions contain crystalline clay minerals of the 2:1 lattice families.
Loss of Phosphorus by Erosion
Authors: Ensminger L. E.
Published: July 2010

A study was made of the phosphorus status of soils which had received phosphate applications over a period of years to determine the loss of phosphorus by erosion. Phosphorus that could not be accounted for by analysis of the surface 16 inches of soil and by crop removal was assumed to be loss by erosion.

Where corn and cotton was used as the rotation, an average of 63% of the phosphorus applied during a 16‐year period to a Hartsells fine sandy loam soil had been lost by erosion as compared to 40% for a corn, cotton, and winter legume rotation. The results show that most of the accumulated phosphorus could be extracted by a HCl‐NH4F solution. Three plots in the corn, cotton, and winter legume rotation contained 7 to 8% of < 2 µ material in the surface 0 to 8 inches originally, but after 16 years of cropping the < 2 µ material had been reduced to 5 to 6%. The clay fraction contained 25 to 30% of the total phosphorus. These results indicate that only a small part of the phosphorus was lost along with the clay fraction. A study of 22 fields in Baldwin County that had been in potatoes from 5 to 30 years shows that the surface soil accumulated an average of 103 pounds P2O5 per acre per year in potatoes, although an estimated 200 pounds of P2O5 was added each year potatoes were grown. An inventory of the phosphorus status of soils in cement bins after 12 years of phosphate applications shows that 80% or more of the applied phosphorus could be accounted for on the basis of soil analysis and crop removal. The plots were enclosed by cement walls which prevented run‐off except during very heavy rains.
Chemical Determination of Sorbed Water and Structural Hydroxyl in Colloidal Minerals of Soils and Sediments
Authors: Evans E. J. , Jackson M. L.
Published: July 2010

A method is described for the differentiation of sorbed water from structural hydroxyl ions for colloidal minerals of soils and sediments. It is based on the extraction of the sorbed water (including external surface sorbed and interlayer water) with methanol. The structural hydoxyl is determined by heating the sample in a silica tube oven, passing a gas through the tube, and collection of the liberated water in methanol. The water contents of the methanol solutions are determined titrimetrically by utilization of the Karl Fischer reagent. This method is preferred to the less satisfactory methods based on thermal weight‐loss. Hydroxyl determinations are given some 2:1 layer silicates and other hydroxyl compounds as examples of the type of studies made possible by the technique.
Status Report on Soil Conditioning Chemicals. II.
Authors: Sherwood L. V. , Engibous J. C.
Published: July 2010

Two synthetic soil conditioning chemicals, hydrolyzed polyacrylonitrile and a modified vinyl acetate maleic acid compound, are described. The effects of conditioner treatment upon the physical, chemical, and biochemical status of the soil, as well as plant composition, yield, and quality are outlined.

Observable results of economic importance are discussed, including improved soil workability, reduced soil crusting, effective erosion control, improved crop yields and quality, and earlier planting and maturity.

Lines of further research are suggested which may ultimately lead to a better understanding of soil structural relationships and the efficient use of soil conditioner chemicals.

Factors influencing specific application recommendations are examined.