bluuebunny/crossref_metadata_2025 huggingface dataset:
Two‐Dimensional Electrophoretic Analysis of Wheat Seed Proteins1
Authors: Anderson Norman G. , Tollaksen Sandra L. , Pascoe Frank H. , Anderson Leigh
Published: July 2010

High resolution two‐dimenslonal (2‐D) electrophoresis with isoelectric focusing in the first dimension and electrophoresis in sodium dodecyl sulfate in acrylamide gradient gels in the second dimension has been used to produce maps of proteins, including glutenins and gliadins, extracted from wheat seeds. Amino acid substitutions producing single or multiple charge changes, and additions or deletions altering protein mass by approximately 2% are visible on these gels; the former produce horizontal displacements in gel patterns, the latter vertical displacements. The thesis that mutations in storage proteins produce grid patterns of variants on 2‐D gels has been examined experimentally, and confirmatory results have been obtained using 14 varieties of wheat. The results suggest that 2‐D analysis will be useful for varietal identification, for classification of storage proteins of wheat, and for studies un the geneology of wheats.
Inheritance of Gliadin Proteins Associated with Quality in Durum Wheat1
Authors: du Cros D. L. , Hare R. A.
Published: July 2010

The inheritance of gliadin protein differences was investigated because prior electrophoretic studies revealed a close relationship between certain endosperm proteins and gluten strength in durum wheat (Triticum turgidum L. var. durum). Particular attention was focused on gliadin band 45, as it is closely associated with dough strength, and on gliadin band 42, which is associated with poor viscoelastic properties. These inheritance studies were conducted on crosses between the two main biotypes of the Australian cv. Duramba. Results from F1, F2, and BC1F1, populations were consistent with the hypothesis that the syntheses of gliadin bands 45 and 42 are controlled by alleles at a single locus. Dosage effects were exhibited by both alleles; however, band 42 displayed a greater degree of dominance than did band 45. These results should prove useful in breeding durum wheat for improved pasta quality.
Phenotypic Recurrent Selection for Resistance to Phytophthora Root Rot in Two Diploid Alfalfa Populations1
Authors: Heisey R. F. , Murphy R. P.
Published: July 2010

The object of this study was to search for resistance to Phytophthora root rot (caused by Phytophthora megasperma Drechs. f. sp. medicaginis) among 10 sources of two wild diploid species of alfalfa, Medicago caerulea Less. and M. falcata L. Phenotypic recurrent selection using a greenhouse screening technique was effective in increasing the levels of resistance in 2 of the 10 sources investigated, M. caerulea (PI 388629) and M. falcata (PI 410970). Resistant plants were not found in the other eight sources. These new sources of resistance may be genetically different from the sources currently available in cultivated autotetrapioid alfalfa (M. sativa L.) L.
Carbon Dioxide Exchange Rate of Tall Fescue—Leaf Area vs. Leaf Weight Basis1
Authors: Wilhelm W. W. , Nelson C. J.
Published: July 2010

The basis used for expression of carbon dioxide exchange rate (CER) of single leaves may alter the relative ranking of genotypes being selected for a breeding program. Therefore, field and growth chamber experiments were conducted on 16 genotypes of tall fescue (Festuca arundinacea Schreb.) to determine the relative merit of expressing CER data on a leaf area or leaf weight basis. Genotypes were grown in plots in the field and in pots in the growth chamber. The CER was measured using an infrared gas analyzer. Herbage yield was determined. Significant genotypic variation within experiments was found for CER when expressed on either a leaf area or leaf weight basis. The correlation coefficient between CER on a leaf area and leaf weight basis ranged from 0.82 to 0.94 for the field experiments and was 0.76 for the growth chamber experiment. Comparision of coefficients of variation (CV's) associated with the two methods of expressing CER indicated slightly higher variation in data based on leaf weight. The CV's for the field experiments were between 11.5 and 16.5%, suggesting that either method of expression of CER for tall fescue could be satisfactorily used to detect genotypic differences. Leaf area is suggested as the preferred base because of its association with radiation interception. Further, genetic control of CER per unit leaf area appears to be independent from specific leaf weight.
Relations Among Relative Leaf Water Content, Growth, and Rubber Accumulation in Guayule1
Authors: Ehrler W. L. , Bucks D. A. , Nakayama F. S.
Published: July 2010

The relative leaf water content (RLWC) was determined guayule (Parthenium argentatum A. Gray) to quantify the effect of soil water deficits on growth and rubber yield. The RLWC was measured from June to November of 1982 in guayule cultivars 593, N565‐II, and 11591 that had been planted in April 1981 at Mesa, AR. The RLWC measurements were made 1 h after solar noon on treatments I1 and I6, where the criterion for irrigation was 75 and 90% depletion of the available water in the 0‐ to 180‐cm soil profile, respectively. This resulted in eight irrigations for I1 (1330 mm) and two for I6 (330 mm). The RLWC averaged 80% for It and ranged from 70% to minima of 30 to 40% for I6. Treatment I6 resulted in statistically significant decreases in height (26%), dry weight (51%), rubber yield (39%), and resin yield (55%). These same components increased significantly from the first to the second harvest: height by 16%, dry weight by 57%, rubber yield by 63%, and resin yield by 79%. There were no significant differences among the three cultivars in any of the foregoing items.
Effect of Water Stress on Canopy Senescence and Carbon Exchange Rates in Cotton1
Authors: Marani A. , Baker D. N. , Reddy V. R. , McKinion J. M.
Published: July 2010

The work reported here was done as part of an effort to develop a physiological process level data base for the simulation of cotton (Gossypium hirsutum L.) growth and yield. The effects of water stress on vegetative growth and on carbon exchange rate (CER) in cotton canopies were investigated in naturally illuminated, controlled environment cabinets (SPAR units). The control treatment was irrigated daily. In the other treatments, irrigation was stopped just before the appearance of the first blooms. An extra low water treatment was allowed to dry much faster than the low water treatment. Water stress had a strong effect on vegetative growth. Rate of increase in plant height and leaf area declined when midday leaf water potential was lower than −1.4 MPa, and they were almost zero at −2.0 to −2.5 MPa. Water stress had a similar effect on the CER over a wide range of radiation intensities. CER started to decline < 2 weeks after irrigation was stopped, and it was about 50% of the control when midday leaf water potential reached −2.0 to −2.5 MPa. Two different mechanisms are suggested for the effect of water stress on canopy photosynthesis. A direct effect on single leaves may have closed stomata, increased mesophyll resistance, or decreased Hill reaction activity. Additionally, there was the long‐term effect of reduced leaf growth, which produced a canopy consisting mainly of old, less photosynthetically efficient leaves.
Cold‐Hardiness Response of Sequential Winter Wheat Tissue Segments to Differing Temperature Regimes1
Authors: Limin A. E. , Fowler D. B.
Published: July 2010

This experiment was initiated to determine if low‐temperature acclimation in one part of a winter wheat plant (Triticum aestivum L.) can influence cold tolerance levels in other plant parts not exposed to cold‐acclimating temperatures. Whole plants and sequential plant segments were exposed to differing temperature regimes in a controlled environment chamber. The level of cold hardiness was determined in whole plant crowns by the regrowth method and in each tissue segment by the leachate conductivity method. Cold hardening of plant parts occurred in dependent of hardiness levels in other parts of the plant. The results indicated that plant response to temperature was the ultimate factor inducing cold hardiness. Reduced tissue moisture content enhanced the cold‐hardening ability of plant tissues, although it also was a plant response to cold acclimating temperatures. The moisture content of upper plant parts was controlled largely by root temperature rather than leaf or crown temperature, although low leaf temperature had some effect on water conductance through the leaves. Tissue segments with low moisture content were more cold hardy than comparable segments with higher moisture content under similar acclimation temperatures. However, tissue segments subjected to cold‐acclimating temperatures achieved greater levels of cold hardiness than comparable tissues of similar moisture content subjected to nonhardening conditions. Exposure temperature was most highly correlated with cold hardiness. Regression analysis indicated that acclimation temperature and tissue moisture content explained a large part of the variation in LT50 (temperature at which 50% of the plants were killed). There was little evidence of any translocatable substance in cold acclimated segments that was able to induce cold hardiness in nonacclimated segments of the plant.
Rhizosheaths on Mesophytic Grasses1
Authors: Duell R. W. , Peacock G. R.
Published: July 2010

Rhizosheaths, soil cylinders on nonbranching roots, have been described on desert grasses. The objectives of this investigation were to determine the frequency of rhizosheaths on mesophytic grasses, assess their ontogenetic development, and evaluates oil conditions, management, and seasonal effects on rhizosheath formation. Rhizosheaths were found on many species of mesophytic grasses growing in diverse soils and moisture conditions. Ontogenetic differences were found. Seedlings attained a critical size before rhizosheaths were discernible on nodal roots. Rhizosheaths were never found on seminal roots. Rhizosheaths persisted through seed development of cereal rye (Secale cereale L.), but deteriorated with heading of perennial ryegrass (Lolium perenne L.). Rhizosheaths were found on both cool and warm‐season perennial grasses occurring as either crop or weedy species. Rhizosheaths occurred in both high and low fertility conditions.
Seasonal Changes and Genetic Variability for DNA Concentration, and Cellular Contents of Soluble Protein, Chlorophyll, Ribulose Bisphosphate Carboxylase, and Pyruvate,Pi Dikinase Activity in Maize Leaves1
Authors: Baer G. R. , Schrader L. E.
Published: July 2010

Photosynthetic enzymes and resistances to CO2 diffusion are likely to limit photosynthetic rates. In order to improve these traits, by classical breeding or genetic engineering, usable genetic variability must be demonstrated, and the effects of the environment should be evaluated. Seasonal changes and genetic variability were determined for pyruvate,Pi dikinase (PPDK) activity, soluble protein, chlorophyll, and DNA for several inbreds of maize (Zea mays L.) grown for 2 years in the field. Ribulose‐l,5‐bisphosphate carboxylase (RuBPCase) activity and quantity (determined immunologically) were measured in 1982. Whereas flow cytometric determinations of the amount of DNA per nucleus revealed less than 15% variability among these inbreds, the DNA concentration in the leaf blades varied up to 50%. These findings suggest that cellular volume of these inbreds varied as much as 50%. It was therefore reasoned that these traits should be expressed on a relative per‐cell basis (i.e., per mg DNA basis) to make meaningful comparisons of the inbreds.DNA concentration in the youngest fully expanded leaf increased at a slow, but relatively constant rate during both seasons. The PPDK activity and RuBPCase concentration were highest around silking, and declined thereafter, about 3 weeks before concentrations of soluble protein and chlorophyll began decreasing. Significant line ✕ time interactions were ascribed to differences in maturity of the inbreds. Significant genetic variability was observed for PPDK activity. From 15 to 18% of the soluble protein was comprised of RuBPCase. The amount of RuBPCase per cell varied up to 50% among inbreds. Inbreds with larger cells (e.g. Mo17 and B73) were generally higher in soluble protein and chlorophyll as compared to inbreds with smaller cells. This conclusion would not have been revealed if the data had been expressed on a basis other than DNA. The significant genetic variability observed for PPDK, RuBPCase, and cell volume provides a basis for further investigations on limitations to photosynthetic rates by these three traits.
Polymers as Moisture Barriers to Maintain Seed Quality1
Authors: West S. H. , Loftin S. K. , Wahl M. , Batich C. D. , Beatty C. L.
Published: July 2010

Soybean [Glycine max (L.)] seed coats readily permit entry moisture and fungi which cause seed deterioration. The seed deterioration process is enhanced by high temperature and high humidity storage conditions. Synthetic coats, which restrict water entry, may prevent deterioration. Soybean seeds were coated with several types of polymers to determine the influence of the polymer on water uptake and on maintaining seed quality. One polymer, poly(vinylidene chloride), was found to reduce water uptake from a 100% relative humidity environment but to increase water uptake from standard germination conditions. These seeds resisted the stress caused by accelerated aging and had less fungal growth than seeds without the synthetic coat. The polymer did not inhibit germination.
Agronomic Comparison of Dwarf and Conventional Height Oat Genotypes1
Authors: Meyers Kenneth B. , Simmons Steve R. , Stuthman Deon D.
Published: July 2010

Development of dwarf stature cultivars has contributed to higher grain yields in wheat (Triticum aestivum L.) and rice (Oryza sativa L.). Although dwarf stature oat (Arena sativa L.) germplasm is available, most oat breeders have not used it in the past because straw yield has traditionally been considered an important agronomic trait. Comparisons of the agronomic performance of dwarf and conventional height genotypes are needed in order to better define the potential value of incorporating dwarf stature into future oat cultivars. From 1982 to 1984 at St. Paul, MN, four experimental dwarf oat genotypes (MN 795929, MN 805928, MN 81160 and MN 82214) were compared with four conventional height genotypes (‘Moore’, ‘Goodland’, ‘Ogle’, and MN 80116) for grain and straw yields, as well as other agronomic characteristics. Plant populations for these studies ranged from 210 to 480 plants m−2. The 1984 experiment was conducted under especially high nitrogen fertilization. There were no differences in grain yield between the dwarfs and conventional height genotypes in 1982 and 1983. The highest yielding dwarf genotype in 1984 produced significantly less grain than the best conventional cultivar. Overall, straw yields of the dwarfs ranged from 73 to 125% of the conventional height lines. However, the highest grain yielding dwarfs in each year had straw yields only about 80 to 90% as high as the highest grain yielding conventional cuitivars. These proportional straw yield differences existed whether the crop was harvested at ground level or at a 15 cm stubble height. Harvest indexes for the highest yielding dwarfs were similar to the conventional height genotypes, even though the dwarfs were about 30% shorter in stature. Panicles of the dwarfs characteristically exserted only partially from the flag leaf sheaths, although this characteristic is being corrected through additional breeding. Such future dwarf lines should be well adapted to intensive management conditions because of their resistance to lodging and may ultimately provide higher grain productivities than can be achieved with conventional height cultivars.
Contributions of Pre‐Silking Assimilate to Grain Yield in Maize1
Authors: Simmons S. R. , Jones R. J.
Published: July 2010

There has been a long‐standing debate among cereal researchers regarding the importance of assimilate remobilization for grain yield. Few estimates have been made of contributions to grain yield of assimilates formed prior to flowering in maize (Zea mays L.). In field studies on a Waukegan silt loam soil (Typic Hapludoll) at St. Paul, MN in 1982 and 1983, one hybrid (A619 ✕ W64A) was grown under conditions of early and late planting and evaluated for the contribution of pre‐silking assimilates to yield. Individual plants were labelled with 14CO2 several times during the pre‐ and post‐silking periods. This treatment was coupled with measurements of changes in aboveground plant dry weight during these same periods. The relative distribution of radioactivity between grain and stover was assessed at maturity. The contribution of pre‐silking assimilates to yield could then be estimated mathematically from the 14C distribution and dry matter change information. Results showed that most assimilates contributing to grain yield were formed after silking. Less than 10% of the final grain yield for either planting date was attributable to pre‐silking assimilate. Both grain yield and absolute contribution of pre‐silking assimilate to yield tended to be lower in later sown plants. We postulate that most of the 14C detected in the grain at maturity from labelling dates before silking was translocated with nitrogen remobilized from vegetative organs. Although small quantitatively, these pre‐silking assimilates may be extremely important for optimum development of the grain.
Preharvest Sprouting of Hard Winter Wheat as Affected by Nitrogen Nutrition1
Authors: Morris Craig F. , Paulsen Gary M.
Published: July 2010

Preharvest sprouting seriously reduces milling and baking quality of hard winter wheat (Triticum aestivum L.) grain. Nitrogen fertilization is used to increase grain yield and protein content, but its effect on preharvest sprouting is unclear. To determine the effect of nitrogen nutrition on preharvest sprouting, five wheat genotypes differing in susceptibility to sprouting were grown in sand with nutrient solution. Differential N regimes were imposed by leaching nutrients from one set of plants at early boot stage (Feekes scale 9), after which complete nutrient solution or solution devoid of N was used until plants were mature. Grain dormancy was assessed 15 days after physiological maturity by treating spikes with simulated rain. Grain from control (no simulated rain) spikes had no preharvest sprouting and low a‐amylase activity in all genotypes. Simulated rain did not cause preharvest sprouting or increase a‐amylase activity in highly resistant genotypes ‘Clark's Cream’ and ‘Lancota’, but increased preharvest sprouting and a‐amylase activity in susceptible genotypes KS75216 and ‘Parker 76’. High N fertility increased absolute α‐amylase activity but not specific α‐amylase activity (activity • mg N−1). We concluded that high levels of fertilization increase rain‐induced preharvest sprouting in genotypes with moderate or low levels of resistance. Nitrogen fertilization probably would not affect preharvest sprouting of genotypes with strong resistance and all genotypes in areas where conditions are not conducive to preharvest sprouting.
Inheritance of Chlorophyll Content, Ribulose‐l,5‐bisphosphate Carboxylase Activity, and Stomatal Resistance in Peas1
Authors: Hobbs S. L. A. , Mahon J. D.
Published: July 2010

Genotypic variability for carbon dioxide exchange rate per unit leaf area (CER) in field‐grown peas (Pisum sativum L.) is positively correlated with chlorophyll content and ribulose‐1,5‐bisphosphate carboxylase (RUBPC‐ase) activity, and negatively correlated with stomatal resistance. To examine the genetic control of these latter three characters, six pea genotypes selected for high or low expression of CER were crossed in all possible combinations to produce a complete diallel. The F2 generation of the crosses and the parental types were evaluated in the field in 1983. Means ranged from 30.8 to 46.0 μg cm−2 for chlorophyll content, from 12.4 to 22.5 nmol s−1 cm−2 for RUBPC‐ase activity, and from 0.44 to 1.25 s cm−1 for stomatal resistance. General Combining Ability (GCA) was significant for all characters and Specific Combining Ability (SCA) was also significant for chlorophyll content and RUBPC‐ase activity. In no instance were reciprocal effects significant. The ratio of sum of squares for GCA to total entry sum of squares indicated that GCA was the predominant genetic component in all characters. Significant SCA effects were only associated with crosses involving certain genotypes (PI244089 and PI244197). The high proportion of additive gene action should allow selection for improvement of these characters, using as parents those genotypes with high positive (or negative in the case of stomatal resistance) GCA effects.
Alfalfa Development, Dry Matter Accumulation, and Partitioning After Surrogate Insect Defoliation of Stubble1
Authors: Buntin G. D. , Pedigo L. P.
Published: July 2010

Stubble defoliation by insects may completely suppress alfalfa, Medicago sativa L., regrowth for several days to 2 weeks. A 2‐year study was conducted to investigate the stubble defoliation for various durations after the first cutting on rates of growth, development, and dry matter partitioning of ‘Valor’ alfalfa. Stubble was defoliated by hand every second day for 0, 1, 3, 7, and 11 days following cutting, Damage was designed to mimic insect injury sufficient to cause complete delays of regrowth. Dry matter was produced slowly for the first 3 days of regrowth. Herbage production quadrupled from day 3 to day 7 and remained high after day 7. Regrowth delays of I and 3 days did not significantly delay plant development or significantly alter rates of growth and partitioning. Delays of 7 and 11 days retarded subsequent plant development and suppressed the crop growth rate (CGR) of subsequent regrowth. An l 1‐day delay reduced CGR by 18.4%, with nearly all this reduction caused by a reduction in growth of leaf‐support structures. Leaf weight and leaf area growth rates were not significantly affected by regrowth delays. Consequently, plants delayed for more than 3 days, produced more leaf area per unit of dry weight through the allocation of greater leaf weight per unit of total weight and greater leaf area per unit of leaf weight. A delay of 11 days resulted in increases of 34.5%, 16.3%, and 15.9% for leaf area ratio, leaf weight ratio, and specific leaf area, respectively. These increases resulted from the production of larger but thinner leaves, which enhanced leaf area more than leaf weight. The results support the hypothesis that leaves have priority for current photosynthesis during the partitioning of photosynthates in alfalfa resulting in the maintenance of leaf growth rates at the expense of support‐structure growth rates.
S1‐line Recurrent Selection for Cold Tolerance in Two Maize Populations1
Authors: Hoard K. G. , Crosbie T. M.
Published: July 2010

S1‐line recurrent selection for improved cold tolerance was evaluated after five cycles in two maize (Zea mays L.) populations, BSI3(SCT) and BSSS2(SCT). Changes in population means for percentage emergence, rate of emergence, seedling dry weight, and seedling vigor score were expressed in terms of changes in allelic frequency, allelic effects, and drift due to restricted population size. Selection resulted in significant genetic gains (2△pα) for percentage emergence (2.1% cycle−1), seedling dry weight (0.04 g cycle−1), and seedling vigor score (0.3 units cycle−1 when averaged over both populations). Estimates of 2△pα were not significant for rate of emergence in either population. Genetic drift (2△p2d) due to restricted population size was significant for seedling dry weight (0.01 g cycle−1) and seedling vigor score (0.1 units cycle−1), emphasizing the need for effective population sizes larger than those used in this study. Estimates of dominance effects were important for percentage emergence and seedling dry weight. Heterosis estimates indicated that BS13(SCT)CO and BSSS2(SCT)CO differed in allelic frequency. Selection increased frequencies of alleles with dominance effects controlling percentage emergence and seedling dry weight. Heterosis for percentage emergence and seedling dry weight decreased with selection. The data indicated that selection for cold tolerance would be effective with use of a selection index including percentage emergence and seedling dry weight, based on data from more than one year. Rate of emergence was not a dependable selection trait.
Genetic Relationships Among Hard Red Winter Wheat Cultivars as Evaluated by Pedigree Analysis and Gliadin Polyacrylamide Gel Electrophoretic Patterns1
Authors: Cox T. S. , Lookhart G. L. , Walker D. E. , Harrell L. G. , Albers L. D. , Rodgers D. M.
Published: July 2010

Genetic relationships for all 903 pairwise combinations of 43 hard red winter wheat cultivars were evaluated using two indices: coefficient of parentage (r), computed from pedigree analysis, and a similarity coefficient (s), based on gliadin polyacrylamide gel electrophoresis (PAGE) patterns. Each index may vary from 0 for two unrelated cultivars to 1 for two identical cultivars. Mean r and s over all cultivars were 0.24 and 0.55, respectively. Cluster analyses based on the r and s matrices revealed dissimilar patterns of relationship in the hard red winter wheat gene pool. When cultivars were separated into two clusters based on the r matrix, mean r within and between clusters was 0.29 and 0.17, respectively. Separation of cultivars into two clusters based on s gave a mean s within and between clusters of 0.60 and 0.49, respectively. The rank correlation coefficient between r and s for all pairs of cultivars was 0.27 (significant at 0.01). Genetic drift and selection probably reduced the correlation between r and s. There was no relationship between ancestor‐cultivar r and s values because of the heterogeneous nature of the ancestors. Efficiency of breeding programs could be improved by computing r values and emphasizing crosses between diverse parents.
Low Temperature Eliminates Heterosis for Growth and Gibberellin Content in Maize1
Authors: Rood S. B. , Major D. J. , Jones M. D. , Pharis R. P.
Published: July 2010

Two Canadian maize (Zea mays L.) inbreds, CM7 and CM49, and their F1 single‐cross hybrid were grown in controlled‐environment conditions in which air and soil temperatures were independently regulated to simulate field conditions at planting during a warm (25/15°C (day/night) air; 17°C soil) or cool (20/10°C air; 12°C soil) spring. Heterosis (overdominance) for height, dry weight, and for concentration of gibberellin (GA)‐like substances occurs with this hybrid when grown under hot temperature conditions [25/20°C (day/night) — air and soil]. Under the decreasing temperature regimes of the present study, growth rate in all genotypes was decreased. While heterosis for increasing plant height was previously observed in the hot conditions, incomplete dominance for increasing plant height was observed in the warm or cool conditions. Potence ratios, indicating the overall degree of dominance, were decreased under the cool temperature regime for height, dry weight, and content of GA‐like substances in apical meristem shoot cylinders. Thus, lowering temperature progressively eliminated heterosis for both growth rate and level of GA‐like substances in the maize hybrid CM7 ✕ CM49. This observed elimination of heterosis at low temperature is inconsistent with one theory of the physiological basis for heterosis which indicates that the hybrid's biochemical polymorphism provides it with superior metabolic buffering of environmental stress. Thus, although the hybrid CM7 ✕ CM49 has a superior growth potential relative to its inbred parents, this potential for hybrid vigor can be suppressed under environmentally unfavorable conditions.
Gross Phloem Anatomy in the Roots of selected C4, C3, and C4‐C3 Intermediate Poaceae Species1
Authors: Rechel Eric A. , Walsh M. A.
Published: July 2010

Is the anatomy and physiology associated with the C4 carbon pathway exclusively a feature of the leaf (photosynthate source)? To assist in establishing a more inclusive knowledge of sourcesink relations, qualitative and quantitative aspects of mature root phloem anatomy were compared between related C4, C3, and C4‐C3 intermediate species, (Triticum aestivum L., Zea mays L., and five Panicum spp.). In all species each phloem bundle was contiguous with the pericycle and separated from any tracheary element by one or two rows of stelar parenchyma. The number of cells between phloem bundles was essentially constant and the spatial relationships among the bundles and the cortex and surrounding stelar tissues were similar in the species studied. One protophloem sieve‐tube element, two companion cells, and one metaphloem sieve‐tube element constituted the basic cellular composition of a bundle. The exception was Z. mays L., in which two to six metaphloem sieve‐tube elements and one or two phloem parenchyma cells were usually present. There were significant differences among these species, but these differences were best explained in terms of species specificity rather than by photosynthetic characteristics.
Inheritance of Three Stearic Acid Mutants of Soybean1
Authors: Graef G. L. , Fehr W. R. , Hammond E. G.
Published: July 2010

Three mutant lines of soybean [Glycine max (L.) Merrill] were identified that had three‐ to six‐fold increases in stearic acid content in the seed oil compared with their parents. Our objective was to determine the inheritance of high stearic acid in the three mutants. Reciprocal crosses were made between each mutant and its parent and among the three mutants. Fatty acid analysis of the seed oil of the parents and the F1, F2, and F3 generations indicated that high stearic acid in the mutants was controlled by a single locus. The Fas allele for low stearic acid in each parent was partially dominant to the allele for high stearic acid in the mutant derived from it. Crosses among the mutants indicated that each possessed a different allele at the same locus. The allele fasa, in the mutant A6, and fas6, in the mutant FA41545, were not dominant to each other. Both fasa and fasb were completely dominant to thefas allele in the mutant A81‐606085. None of the segregates from the mutant ✕ mutant crosses had a stearic acid content outside the range of the parents. Maternal and cytoplasmic effects were not important in the control of stearic acid content in these mutants.
Predictive Models for the Growth Response of Eight Azolla Accessions to Climatic Variables1
Authors: Lumpkin T. A. , Bartholomew D. P.
Published: July 2010

Although the freefloating aquatic fern Azolla pinnata has been grown for centuries in northern Vietnam and southeastern China as a nitrogen‐fixing green manure for rice and as a fodder for pigs, little is known of the environmental tolerance of the seven known Azolla species. In this study, the relative growth rates (RGR) of A. caroliniana, A. filiculoides, A. mexicana, A. microphylla, A. nilotica, A. pinnata var. pinnata, A. pinnata var. imbricata, and A. rubra were evaluated over a wide range of climatic conditions. The species were grown on nitrogen‐free nutrient solution under a glass roof at a site where air temperatures ranged from −7°C in the winter to 38°C in the summer.The RGR was calculated from increases in dry weight over 26 growth cycles of one week to 1 month. The RGRs of individual species were most closely related to minimum water temperature during spring and fall (R2 = 0.67 to 0.99); minimum water temperature and daylength for spring plus fall (R2 = 0.59 to 0.92); and minimum water temperature, solar radiation, and relative humidity during summer (R2 = 0.66 to 0.85). This study suggests that temperature, daylength, solar radiation and relative humidity can be used for estimating the RGR of Azolla.
Analysis of Alfalfa Root Carbohydrate Concentration by Near Infrared Reflectance Spectroscopy1
Authors: Brink G. E. , Marten G. C.
Published: July 2010

Near infrared reflectance spectroscopy (NIRS) has been used to evaluate forage plants primarily for their feeding quality. Our objective was to determine whether NIRS could also accurately measure the root total nonstructural carbohydrate (TNC) concentration of alfalfa (Medicago saliva L.) established by various methods and grown to a wide range of maturities in several environments. We assayed root TNC concentration of two alfalfa cultivars harvested by eight cutting schedules in each of 2 years after establishment and of one cultivar during the year of establishment with and without companion crops harvested at various small grain maturation stages within each of 2 years. Calibration equations for TNC concentration were obtained by multiple linear regression of conventional laboratory assay values on NIR spectra from 54 randomly selected samples using a scanning monochromator NIR spectro‐computer system. Calibration equations were verified with 18 additional samples selected from the original population. Five wavelengths were required to produce the best equation for TNC concentration analysis for each of the data treatments (log 1/R, first derivative, and second derivative). The squared coefficients of multiple determination (R2) of the three equations ranged from 0.98 to 0.99. The lowest standard error of analysis by NIRS of TNC concentration in verification samples was 1.17 dag kg−1 (%) dry weight for the log 1/R data treatment. We conclude that NIRS can analyze the TNC concentration of alfalfa roots more conveniently than, and as accurately as, conventional laboratory techniques and that accurate and precise analysis is not limited to a single mathematical treatment of the NIR data.
Tetrazolium Chloride Test for Spring Wheat Seedling Vigor at Low Temperatures1
Authors: Johnston W. J. , Yusuf H. A. , Konzak C. F. , Maguire J. D.
Published: July 2010

Low soil temperature is a major environmental factor limiting seedling establishment of early sown spring wheat [Triticum aestivum (L.)]. This laboratory study was conducted to determine if a red pigment, formazan, extracted from tetrazolium chloride (TZ)‐treated embryos could be used as a rapid quantitative test to screen spring wheat cultivars for low temperature seedling vigor. The effects of several factors were considered in developing the screening technique. These were seed size, sample size, length and temperature of the imbibition period, and the correlation of formazan optical density (OD) values with vigor. Seeds of different size categories were imbibed for various time periods at test temperatures (5, 7, or 10°C) prior to the addition of TZ. Formazan was then extracted and OD readings were obtained. Vigor was estimated by measuring shoot length after growth in the dark for 20 days at 10°C or 31 days at 5°C in a water culture medium. Seedling dry weight was also taken after 20 days growth at 10°C. Test results showed that differences among the genotypes for seedling vigor were correlated with formazan OD values. The larger the seed size class the greater the TZ reduction ability. Either five or 10 seeds per genotype were shown to give good genotype separation with low coefficients of variability. Genotypic differences in TZ reduction were apparent after 4 or 5 days imbibition at 5°C or 2 or 3 days imbibition at 10°C. At 7°C, genotypic differences in TZ reduction were apparent at 3, 4, or 5 days. A 4‐day imbibition period at 7°C appeared to. offer the greatest efficiency for genotypic screening. The test promises to be a simple, comparatively rapid, and reliable method for screening wheat genotypes for low temperature seedling vigor.
Grain Sorghum Hybrid Interactions with Tillage System and Planting Dates1
Authors: Francis C. A. , Moomaw R. S. , Rajewski J. F. , Saeed Mohammad
Published: July 2010

Alternative tillage systems used with improved cultural practices are among the changes necessary to increase agricultural productivity. Farmers and the commercial seed industry are concerned whether existing hybrids will optimize yield in new systems. This research tested hybrid ✕ cultural system interactions in grain sorghum (Sorghum bicolor (L.) Moench) on a Culumic Haplaquoll soil. Nineteen hybrids were compared in eight experiments using zero vs. conservation tillage and early vs. late planting dates in 1978 and 1979 at Concord, NE. Mean grain yields ranged from 8 790 kg ha ' in early planted zero tillage plots in 1978 to 5 740 kg ha−1 in late planted conservation tillage plots in 1979. Eight superior hybrids in 1978 were also best in 1979 across cultural systems. Highest yields consistently occurred with zero tillage and early planting. Interaction of hybrid grain yield with planting date or tillage system was minimal. When 2‐yr means of hybrids were compared for the two tillage practices, there was a highly significant (P < 0.01) correlation (r = 0.87) among hybrid yields. There also was a highly significant (P < 0.01) correlation (r = 0.70 to 0.87) among hybrid grain yields between the two planting dates. Results suggest that plant breeders and farmers should find current hybrids well suited to changes in cultural practices in northeast Nebraska.
Inheritance of Leucoanthocyanidin Content in Sorghum Leaves1
Authors: Haskins F. A. , Gorz H. J.
Published: July 2010

Leucoanthocyanidins (LAC) are structurally related to condensed tannins, a class of compounds having significant effects on the nutritional value of sorghum [Sorghum bicolor (L.) Moench] grain. Little is known of LAC inheritance in sorghum. Mature leaves of ‘Coiman’ and ‘White Collier’ forage sorghum are high and low, respectively, in LAC content. The objective of the present study was to determine the inheritance of LAC content in reciprocal crosses between these two cultivars. Leaves of field‐grown plants were assayed for LAC by a procedure that involved treating methanolic leaf extracts with acid at 50°C to convert the colorless LAC to an anthocyanidin having an absorbance maximum near 540 nm. Parental, F1, and F2 plants were grown and assayed in 1983. In 1984, F3 progenies from selected F2 plants representing various LAC levels were grown and assayed a long with additional F2 and parental plants. Results from both years supported the conclusion that a single allelic pair with incomplete dominance was primarily responsible for the difference in LAC content between Colman and White Collier plants. Other genes with minor effects may also be involved, but maternal or cytoplasmic effects were not important in determining LAC level. The LAC of Colman was not identified, but based on the work of other researchers with other sorghums, it is probably apiforol.
Effect of Light Level on Dinitrogen Fixation and Carbohydrate Distribution in Virginia Peanuts1
Authors: Farnham M. W. , Gross H. D. , Cappy J. J.
Published: July 2010

The peanut (Arachis hypogaea L.) is an important grain legume world‐wide, yet the N2 fixation capabilities of this crop have received minimal attention. An experiment was conducted to study the effects of radiant flux on peanut growth, N2 fixation, and the distribution of nonstructural carbohydrates among plant parts during vegetative and early‐reproductive growth stages. Two Virginia‐type cultivars, NC4 and NC6, were grown in controlled‐environment chambers under average photon flux treatments of 230 and 650 µimol photon m−2 s−1. Plants grown under the higher irradiance accumulated three times more dry matter, fixed three times more N2, and had greater reproductive potential than plants under the low irradiance. The greater fixation in plants under high light was attributed to an increased effective nodule mass in those plants and not to a greater efficiency of nodules to fix N2. There were no significant cultivar differences for dry matter or N accumulation, although NC4 was always slightly higher than NC6. Concentrations of nonstructural carbohydrates in peanut tissues varied depending on the growth stage. The content of carbohydrates in root, stem, and leaf tissues was greater in high‐light plants, compared with plants under low light. Within the high‐light treatment, carbohydrate content was greatest in tissues of NC4 plants. Carbohydrate concentration in nodules was not significantly different between light treatments.
Spatial Distribution of Seed Yield within Plants of Bean1
Authors: De Moura R. L. , Foster K. W.
Published: July 2010

Seed yield in common bean (Phaseolus vulgaris L.) is subjected to various stresses including high plant populations. Thus, yield may depend on the spatial distribution of vegetative and reproductive structures. This study was initiated to determine the spatial and temporal distribution pattern in terms of main stem and branch node positions of seed yield in four dry bean cultivars: ‘Red Kidney’, ‘Sacramento’, ‘Sutter Pink’, and ‘T‐39’. These cultivars were planted at Davis, CA, in the summer of 1983. Each plot was two rows per bed, spaced 76 cm apart, and thinned to an intrarow spacing of 23 cm. Each plot consisted of five randomly selected plants. Beginning at first flower, each flower that opened each day was tagged daily over the next 20 days. The spatial distribution pattern (a result of pods being set at various main stem and branch nodes) of yield showed approximately 70% of the total yield to be in the lower portion of the canopy, i.e., Branches and main stem Nodes 1 to 3 in Red Kidney, Sacramento, and Sutter Pink, and Nodes 1 to 5 in T‐39. Considering the branches only, 70% of the total yield was produced on branch Nodes 1 to 3 in Red Kidney, Sacramento, and Sutter Pink, and branch Nodes 1 to 5 in T‐39. The main stem yield varied among cultivars, ranging from 7 to 23% of total yield. Distribution of pods at nodes along the main stem varied among cultivars, with those of Red Kidney and Sacramento concentrated at Node 5 or 6 while Sutter Pink and T‐39 had pods distributed over a greater portion of the stem and had maximum main stem pod production at Node 6 (Sutter Pink) or 9 to 10 (T‐39). Combining spatial and temporal data showed that the percentage of early pods set at a single location was greatest near the main stem and decreased at more distant nodes. The majority of pods produced on the main stem were set during the first 11 days of the reproductive period. Present architecture of the four cultivars tested shows that a large percentage of the yield is located on the lowest branches. Therefore, the development of new cultivars for direct combining higher planting densities will require plant types with more pods on the main stem and/or a major portion produced on the higher branches.
Effects of Cultivar and Flower Removal Treatments on the Temporal Distribution of Reproductive Structures in Bean1
Authors: De Moura R. L. , Foster K. W.
Published: July 2010

Patterns of flower and pod production vary in time and in space among different cultivars and in response to environmental variables. A quantitative description of these variables will be important in studies in both stress‐management and cultivar development. Three experiments were conducted to determine the temporal distribution of flowering and the effects of flower removal on flower production and seed yield in dry bean (Phaseolus vulgaris L.). All experiments were planted at Davis, CA, on beds having 76‐cm centers. Experiments were conducted in different years, each experiment being a randomized complete block, having a minimum of four replications. In the cultivar comparison experiments, flowers of ‘Sacramento’, ‘Red Kidney’, ‘Sutter Pink’, and ‘T‐39’ were tagged over a 20‐day period beginning at first flower. By Day 12 or 13, all cultivars had reached peak flower production and had set pods, which would eventually constitute approximately 80% of their total seed yield. The rate of flower production differed among cultivars, but the earliest produced flowers had the highest pod set percentage. In the defloration experiment, flowers of Red Kidney and ‘California Red’ were removed or counted during various 10‐day intervals or combinations thereof over a 30‐day period. Removal of flowers during the first 20 days resulted in a significant increase in flower production during the last 10 days. Flower removal during Days 11 to 20 had the greatest impact on seed yield. In the partial defloration experiment whera e fixed proportion of flowers (e.g., every fourth flower) were removed over the entire season; flower production or yield was not significantly affected. A minimum of 20 days of flowering and pod set is essential for high yields. Stresses causing flower loss or pod abortion during Days 11 to 20 will have a significant impact on yield.
Sheep Grazing Effects on Subterranean Clover Development and Seed Production in Western Oregon1
Authors: Steiner J. J. , Grabe D. F.
Published: July 2010

This study was conducted to determine which sheep (Ovis aries) grazing practices could be used to increase seed yields of subterranean clover (Trifolium subterraneum L.) and to study the effects of sheep grazing on plant growth. A further objective was to describe the effects of natural moisture stress in the field on seed production. Four sheep grazing treatments were applied in 1979 and 1980 at a constant stocking rate of 5 and 7.5 ewes/ha, respectively. The location was a hill‐land site mapped as a loamy mixed non‐acid mesic shallow Typic Xerorthents, loamy mixed mesic shallow Dystic Xerochrept, fine mixed mesic Ultic Haploxeralfs, and fine‐loamy over clayey mixed mesic Ultic Haploxeralf. The duration of the grazing treatments was controlled with wire‐mesh exclosure cages. Extended grazing applied from before flowering until early bur formation increased seed yields over the ungrazed control by 51 and 27% (234 and 223 kg/ha) in 1979 and 1980, respectively. Two grazing treatments of a shorter duration during this period were not as effective in increasing seed yields. While grazing pressure was being applied, leaf area index, canopy height, and the amount of light absorbed by the canopy was reduced in the extended grazing treatment. Natural variations in soil depth within the experimental area resulted in varying amounts of moisture stress to the crop when rainfall was limited in the 1979 season. Seed yield, seed number, and seed size (g/100) showed correlations of −0.84, −0.80, and −0.84 (P = 0.001), respectively, with increasing moisture stress. Leaf area index, leaf dry weight, and total stem dry weight were reduced equally over the moisture stress levels for both the extended grazing and ungrazed treatments. However, the total amount of dry matter regenerated in the extended grazing treatment was less as moisture stress increased. This left more moisture available for reproductive development. Sheep grazing is essential if maximum seed yields are to be obtained from subterranean clover fields in western Oregon. The optimum grazing period is from just prior to the start of flowering until the time of early bur fill.
Cotton Resistance to 2,4‐Dichlorophenoxy Acetic Acid Spray Drift1
Authors: Regier Cecil , Dilbeck R. E. , Undersander D. J. , Quisenberry J. E.
Published: July 2010

Cotton (Gossypium hirsutum L.) is very sensitive to the phenoxy herbicides, in particular, 2,4‐dichlorophenoxy acetic acid (2,4‐D). This sensitivity results in damage causing significant economic loss each year. A study was conducted at the Texas Agricultural Experiment Station, Etter, TX, on a sherm silty clay loam soil (fine, mixed, mesic, Torrertic Paleustoll) in 1981 and 1982 to determine if there were genetic variability for resistance to 2,4,‐D damage. Twelve medium‐early and early cultivars of cotton were grown under limited irrigation. In mid‐June of each year, the cuitivars were exposed to 2,4‐D drift from farmer applications on neighboring fields. One cultivar, Paymaster 145, consistantly showed less 2,4‐D damage and correspondingly higher yields. Gin turnout and micronaire were also negatively correlated with 2,4‐D damage, while staple length was positively correlated.