bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphological Identification of St. Augustinegrass Cultivars1
Authors: Busey Philip
Published: July 2010

A vegetatively propagated crop such as St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] should consist of distinctive, easily identifiable cultivars. The purpose of this study was to improve identification criteria for this species and measure the frequencies of various St. Augustinegrass cultivars in Florida. Morphological traits were recorded in 242 unknown Florida St. Augustinegrass lawn and sod samples, which had been transplanted and grown outdoors in containers with 16 known clonal cultivars and taxonomic representatives. Lawn and sod samples conformed mostly to the expected morphological distributions of ‘Floratam’, ‘Bitterblue’, and a heterogeneous ‘Roselawn’‐like complex. The latter clones were distinctive because of their intermediate‐sized (4.6 to 4.8 ram) spikelets, relatively long floral regions (measured from the base of the lowermost spikelet to the tip of the inflorescence), and long, narrow internodes. Therefore, they were named the Longicaudatus (“long‐stemmed”) Race. Clones with short (<4.5 mm) spikelets were also distinctive and were named the Breviflorus Race, however, this race was virtually absent in Florida. Spikelet length and length of the floral region separated known cultivars in 84 of 91 pairwise comparisons (P<0.05), and these two traits showed no detectable environmental variance between containers and field plots. Inclusion of floral traits in discriminant analysis increased the proportion of unknown clones that could be identified from 49% (with vegetative traits only) to 95%. Keys using vegetative field traits and replicated container measurements were 93% accurate in identification of knowns, and 86 to 96% consistent with discriminant analysis in identification of unknowns.
Leaf Photosynthesis and its Correlation with Leaf Area1
Authors: Bhagsari A. S. , Brown R. H.
Published: July 2010

Comparisons among cultivars of leaf CO2 exchange rate (CER) based on leaf area may be confounded by leaf characteristics not usually accounted for in such comparisons. One such confounding characteristic appears to be leaf size. Correlation coefficients between leaf CER and leaf area (LA) were determined for genotypes of peanut (Arachis hypogaea L.), soybean [Glycine max (L.) Merr.], and sweet potato (Ipomoea batatas L.) and were compared with correlations for other crops reported in the literature. There were negative correlations between CER and LA in all crops examined. Significant negative correlations between LA and dark respiration were observed for wheat (Triticum sp.), alfalfa, (Medicago sativa L.), and peanut. Leaf area was negatively correlated with transpiration per unit LA and with leaf conductance for soybean. The relationship between leaf size and specific leaf weight was inconsistent in most crops. Comparisons of CER for genotypes having different leaf sizes may not represent the inherent differences in photosynthetic potential. Negative correlations between LA and CER may be one of the causes for the absence of consistent relationships between CER and yield.
Cotton Resistance to the Root Knot‐Fusarium Wilt Complex. II. Relation to Root‐Knot Resistance and its Implications on Breeding for Resistance1
Authors: Shepherd Raymond L.
Published: July 2010

The fusarium wilt fungus, Fusarium oxysporum Schlect f. vasinfectum [(Atk.) Synd.& Hans.], and the root‐knot nematode (RKN) [Meloidogyne incognita (Kofoid & White) Chitwood] cause a destructive disease complex in cotton (Gossypium hirsutum L.). This study was conducted to determine the range of genetic resistance to RKN in a group of 18 cotton cultivars and breeding lines, to evaluate the relationship between genes for resistance to fusarium wilt disease (FW) and the genes for RKN resistance, and to ascertain the relative importance of the two types of resistance in controlling FW. Numbers of RKN eggs produced on the cottons ranged from <1000/plant on Auburn 623 RNR to >148 000/plant on ‘Rowden’. One‐eighth as many and 18 times more RKN eggs/plant were produced on Auburn 623 RNR and Rowden in 40 days, respectively, than were used to inoculate them. No commercial cultivar was resistance to RKN in this study. Two cotton cultivars expressed genetic resistance that provided moderate field resistance to FW independently of RKN resistance. Differences in resistance to FW in the field among cotton cultivars and breeding lines were determined more by RKN resistance than by genetic resistance to FW. Results indicate that cotton can be developed with genetic resistance to FW independently of RKN resistance and that this genetic resistance probably would provide moderate field resistance to FW. High field resistance to the RKN‐FW complex depends on high RKN resistance, and cotton cultivars with high RKN resistance probably would have adequate field resistance to this complex even if they were genetically susceptible to FW.
Effects of Recurrent Selection for Cold Tolerance on Genotype‐Environment Interactions for Cold Tolerance and Agronomic Traits in Two Maize Populations1
Authors: Hoard K. G. , Crosbie T. M.
Published: July 2010

The effects of recurrent selection in maize (Zea mays L.) for cold tolerance on genotypic ✕ environmental (G ✕ E) interactions for cold tolerance and other agronomic traits were studied using stability analyses. Selection altered G ✕ E interactions of traits subjected to direct selection (seedling dry weight and percentage emergence), but did not cause indirect selection effects in G ✕ E for seedling vigor score, grain yield, root lodging resistance, or grain moisture. Selected cycles had significantly higher and lower regression coefficients determined by the 1966 Eberhart‐Russell stability analyses for seedling dry weight and percentage emergence, respectively, than did the original populations. Use of the 1978 stability analysis by Moll and coworkers indicated that selected cycles had greater responsiveness in seedling dry weight to environmental variation and lower responsiveness in percentage emergence. Direct gain from selection was greatest in warmer environments for seedling dry weight and was greatest in cooler environments for percentage emergence. A stability analysis utilizing accumulated heat units as a physical assessment of environments was not an accurate measurement of environmental factors affecting these cold tolerance traits. Using the Eberhart‐Russell stability‐analyses, we found that regression coefficients of the selected cycles and original populations were not significantly different for seedling vigor score, grain yield, or root lodging resistance. Selected cycles had significantly lower regression coefficients than did the original populations for grain moisture. However, this change in G ✕ E by selection could not be simply interpreted in terms of responsiveness or correlations of entries in different environments. The data suggest that G ✕ E interactions may be altered for traits under direct recurrent selection, but not necessarily for correlated traits.
Primary Trisomics in Sugarbeet. I. Isolation and Morphological Characterization1
Authors: Romagosa I. , Hecker R. J. , Tsuchiya T. , Lasa J. M.
Published: July 2010

All nines sugarbeet (Beta vulgaris L.) primary trisomic types were established from a total of 48 trisomic plants isolated in the progeny of autotriploids of two closely related sugarbeet lines, one homozygous annual and one inbred biennial. Based on morphology, 42 of these trisomic plants were classified into eight morphologically distinct groups. Cytological identification of the extra chromosome of these eight group as and of the ninth type was accomplished by karyotype analysis in somatic cells. Ten leaf and petiole measurements were taken on 3‐ to 4‐month‐old plants grown in two different environments. Although significant differences existed between diploid and trisomic types, and any two trisomic types differed by at least three variables, no single trait could distinguish more than four groups of trisomic types. Discriminant analysis was performed on leaf measurements for seven trisomic types and their diploid sibs. For these closely related lines it was found that the discriminant functions classified most plants (97%) correctly within a given environment. However, the value of the measurements depended on the specific environment where the trisomics were grown, and only 44% of the leaves of diploid and trisomic plants grown in a second environment were correctly classified using the discriminant functions of the first environment. This fact precludes the use of the same discriminant functions for classification purposes over a series of different environments, although these functions might be useful in a standard controlled environment.
Physiological Effects of the Form of Nitrogen on Corn Root Tips: A 31P Nuclear Magnetic Resonance Study1
Authors: Andrade Fernando H. , Anderson I. C.
Published: July 2010

Physiological effects of different N forms(NO−3, NH+4, or a combination of both) on corn (Zea mays L.) root tips and leaves were studied by following 31P signals with a nuclear magnetic resonance spectrometer. With root tips, both cytoplasmic and vacuolar pH could be measured, whereas with leaves, only vacuolar pH could be determined. The N treatments did not affect the cytoplasmic pH of corn root tips in contrast to proposals of previous workers. Leaf vacuolar pH was higher and root tip vacuolar pH lower with NO−3 than with NH+4. Under anaerobic conditions, cytoplasmic pH was reduced because of lactic acid fermentation. Nitrate, an electron acceptor, delayed the acidification of the cytoplasm compartment because it represents an alternative way to reoxidize NADH. In conclusion, for the conditions of these experiments, the pH of the cytoplasm of corn root tips was not modified by the form of N absorbed; however, the pH of this compartment was affected by the form of N presented during development anaerobiosi.
Inheritance of Partial Hull in Safflower1
Authors: Urie A. L.
Published: July 2010

The pericarp (hull) of safflower (Carthamus tinctorius L.) seed is high in fiber, whereas the embryo portion of the seed is high in oil and protein. Reducing the hull portion of the seed would increase product value. A new hull character in safflower has been identified as partial hull. A field nursery grown partial‐hull plant produces 94% partially dark seeds and 6% white seeds with small dark blotches, which indicates a reduced hull portion. Seeds from partial‐hull plants produced in a greenhouse or under selfing bags exhibit more whitehull expression. The objectives of the present study were: i) to quantify the level of expression of the dark areas of the pericarp of partial hull when compared to other hull types, and ii) to determine the inheritance of partial hull when crossed with white hull (thick normal hull), reduced hull, striped hull, and thin hull. Segregation of partial hull was determined by observing the frequency of plants that produced seeds with predominantly dark or blotched hulls vs. plants that produced seeds with white hulls. Analysis of F1, F2, and F3 progenies showed that partial hull is recessive to white hull and reduced hull, but is inherited independently of striped hull and thin hull. The pericarp thickness of parents used in crosses with partial hull can influence level of expression of partial hull in filial generations. It is suggested that the recessive gene controlling partial‐hull pericarp expression be designated par. The partial‐hull gene may be useful in safflower breeding programs as a means to increase both oil and protein percentage of the seed. The presence of the partial‐hull gene can be visually identified in filial generations.
Mass Selection for Increased Seed Protein Concentration of Wheat Based on Seed Density1
Authors: Peterson C. J. , Liu G. T. , Mattern P. J. , Johnson V. A. , Kuhr S. L.
Published: July 2010

Seed density selection to increase the seed protein concentration of wheat (Triticum aestivum L.) has not been effective due to the small difference in the dry densities of starch (1.60 Mg m‐3) and protein (1.40 to 1.45 Mg m‐3). In this study, water imbibition wheat seeds for 9 to 10 days at 0 to 3°C was shown to enhance the differential densities of protein and starch. Linear relationships between protein concentration and imbibedensity, and protein concentration and water absorption of wheat seed were demonstrated in samples of three bulk populations and ‘Bennett’ separated in CCl4‐ hexane solvents ranging in density from 1.16 to 1.28 Mg m‐3. An inexpensive and nontoxic solution of sucrose and NaCI was shown to be an effective medium for density separations of seed. Less dense seeds were separated from 52 early generation bulk wheat populations after low temperature seed imbibition using sucrose‐NaCl solutions. The seeds were rinsed, dried, and planted alongside samples of the original populations at Lincoln, NE and Vernon, TX. Analyses of seed after harvest showed that protein concentrations of I0 of the 52 populations were increased by low seed density selection. Increases in protein concentration ranged from 6 to 11 g kg‐1 and seed weights of the populations were unaffected by selection. A large amount of nongenetic variation in protein concentration of individual seeds appears to limit the effectiveness of seed density selection for increasing protein concentrations of wheat seed.
Covariance between Line per se and Testcross Performance1
Authors: Smith O. S.
Published: July 2010

The relationship between line per se and testcross performance was evaluated theoretically to examine possible reasons for the low values, reported in the literature, for this correlation. An expression for the correlation between line per se and testcross performance was developed. This expression was evaluated using restrictive assumptions for allellic frequencies and effects. Computer simulation was used to estimate the correlations in the more general case. These results indicated that, for traits conditioned by a large number of loci showing complete dominance, the correlations between line perse and testcross performance are expected to be less than 0.5. This is due to the masking effects of favorable dominant alleles in the tester. The computer simulation results agree with previous empirical results which showed that use of a high performance (good) tester will reduce the genetic variance among testcrosses. Additionally, the use of a good tester reduced the correlation between line per se and testcross performance. Correlations between line per se and testcross performance to a related (tester from the same population) and unrelated (tester from a different heterotic group) tester also were examined in the simulation study. Correlations were generally low, although higher for testcrosses to a good unrelated tester than for testcrosses to a good related tester.
Effects of Temperature, Moisture Stress, and Seed Size on Germination of Nine Spring Wheat Cultivars1
Authors: Lafond G. P. , Baker R. J.
Published: July 2010

To determine if spring wheat (Triticum aestivum L.) cultivars show differential germination responses to varying levels of temperature and moisture stress, various seed‐size lots of nine cultivars were germinated in water at 5, 8, 12, 20, and 30°C, and in polyethylene glycol (PEG 8000) solutions with osmotic potentials of 0.0, ‐0.4, and ‐0.8 MPa at 10 and 20°C. Numbers of germinated seeds were recorded at intervals of 4 to 12 h depending upon temperature and stage of germination. Germination was expressed as a cumulative percentage of the number of seeds germinated by the final recording and, because of the unequal intervals between successive recordings, germination‐time curves were described as logistic functions of time. Each curve was characterized by final germination percentage, median germination time, and maximum rate of germination. Final germination exceeded 90% in all instances. At 20°C, cultivars differed by as much as 7 h in median germination time. Cultivar differences were consistent, though decreasing in magnitude, as temperature increased from 5 to 30°C. Differences in median germination time could not be attributed to differences in rate of water uptake. The reciprocal of median germination time, a measure of rate of germination, was linearly related to temperature. Small seeds germinated faster than large seeds in all cases. Increasing osmotic moisture stress from 0.0 to −0.8 MPa caused median germination time to increase from 90 to 156 h at 10°C and from 36 to 64 h at 20°C. Relative germination times of the cultivars were consistent over the different levels of osmotic moisture stress.
Characteristics of Reproductive Abortion in Soybean1
Authors: Heitholt James J. , Egli D. B. , Leggett J. E.
Published: July 2010

The abortion of reproductive plant parts is an important, but not well understood, part of the yield production process in many crop plants. The objective of this research was to characterize the effects of growth stage and timing on the abortion process of soybean [Glycine max (L.) Merr.] flowers exhibiting variation in abortion. Soybean plants were grown in a greenhouse (cv. McCall) and for 3 yrs in the field (cv. Kent). The soil types were a Donerail silt loam (Typic Arguidofl), Maury silt loam (Typic Paleudalf), and a Lanton silt loam (Cumulic Haplaquolls). Fully‐opened flowers located on nodes from the middle of the main stem were marked during early (R1) and late (R3) flowering and then observed for 2 or 3 weeks to determine the extent and timing of flower abortion. Defoliation and three different depodding treatments were used to alter abortion. Nineteen percent of the early flowers aborted (failed to produce seed bearing pod) in the greenhouse, but 31 to 48% aborted over yrs in the field. Abortion of late flowers varied from 76 to 92% in two greenhouse experiments and from 69 to 90% in the three field experiments. The abortion process occurred more rapidly in the greenhouse where much of the abortion was apparent by 6 days after flower opening (DAFO), compared with the field where less than 50% of the abortion was apparent by 10 DAFO. The three depodding treatments decreased and defoliation increased flower abortion. Removing all pods from a plant except those at one node, reduced late flower abortion at that node from 69 to 54%. However, removing all pods from only one node of the plant reduced abortion at that node from 69 to 36%. The results of these experiments suggest that the processes controlling abortion operate at the individual node level and that the whole plant source‐sink ratio is of secondary importance.
Techniques for Identifying Tolerance of Soybean to Phytotoxic Substances in Wheat Straw1
Authors: Herrin L. L. , Collins F. C. , Caviness C. E.
Published: July 2010

Experiments have shown that substances in wheat (Triticum aestivum L.) straw are phytotoxic to soybean [Glycine max (L.) Merr.]. We evaluated techniques for screening soybean germplasm to these growth‐reducing substances and studied factors affecting this trait. Techniques used were: i) pots in a greenhouse, ii) large wooden flats in a greenhouse, and iii) field evaluations. The soil mixture in the greenhouse contained 20 g straw/kg soil. Results from the flat technique were highly correlated with the pot method, the technique commonly used. Field evaluations were not highly correlated with greenhouse results. Seed age and seed source affected the tolerant response, whereas seed size was not an important factor.
Cluster Analysis of Red Winter Wheat Cultivars Based upon Coefficients of Parentage1
Authors: Murphy J. P. , Cox T. S. , Rodgers D. M.
Published: July 2010

Cluster analysis was conducted using the coefficients of parentage (r) between all pairwise combinations of 110 recently released or historically important red winter wheat (Triticum aestivum L.) cultivars. The objectives were to determine the overall pattern of relationships and to search for genetic clusters within the soft red winter (SRW) and hard red winter (HRW) wheat gene pools. The two classes contained overlapping germplasm (r̄ between the two classes = 0.05). Thirty‐eight SRW cultivars formed six clusters based on predominant parents (‘Arthur’, ‘Benhur’, ‘Coker 68‐15’, ‘Lucas’, ‘Knox’, and ‘Blueboy’), whereas 49 HRW cultivars formed seven clusters (based on ‘Triumph’, ‘Sturdy’, ‘Scout’, ‘Blackhull’‐ ‘Tenmarq’, ‘Turkey’, ‘Parker’‐‘Centurk’, and ‘Warrior’). Principal coordinate analysis separated these 13 clusters primarily by class (HRW vs. SRW), but also by geographical origin of predominant parents within classes. These results may have application in parental selection for conventional cultivar, hybrid cultivar, and population development in winter wheat.
Variation in Epicuticular Wax Content of Alfalfa Cultivars and Clones1
Authors: Galeano R. , Rumbaugh M. D. , Johnson D. A. , Bushnell J. L.
Published: July 2010

Increased epicuticular wax per unit leaf area has been suggested as a potential mechanism for decreasing cuticular transpiration of plants and for reducing the incidence of bloat when ruminants graze legumes. The objectives of this study were to quantify the epicuticular wax content of some alfalfa (Medicago sativa L.) cultivars and clones and to estimate the heritability of the trait. Epicuticular wax amounts were measured by extraction with carbon tetrachloride and gravimetric procedures in 28 cultivars and 100 clones of alfalfa during two harvest periods. The effects of cultivars, clones, sampling periods, test sites, and most of their interactions were statistically significant. Seasonal averages of epicuticular wax ranged from 4.62 to 8.82 g kg−1 among the cultivars and from 2.94 to 10.38 g kg−1 among the clones. Cultivar and clone rankings were quite consistent in the different environments. Broad sense heritability (H) of wax amount for the clones was 0.99, indicating that epicuticular wax of alfalfa could be increased by breeding and selection.
Storage Protein Accumulation in ‘Scio’ Barley Seed as Affected by late Foliar Applications of Nitrogen1
Authors: Turley Robert H. , Ching Te May
Published: July 2010

Late foliar applied N (LFAN) can improve seed protein content but the mechanisms involved are not well known. This study was conducted to determine how LFAN is accumulated in small grains so that cultural or biotechnological procedures can be developed to increase cereal proteins for food. ‘Scio‘ barley (Hordeum vulgare L.) was foliar sprayed with urea‐ammonium nitrate (UAN, 1:1 by weight) at 9 days before anthesis and 18 days after anthesis (DAA) at 72 and 87 kg (N) ha ', respectively, in 1983. In 1984, 28 kg (N) ha−1 of urea was applied on soil 8 weeks before anthesis and two foliar UAN at 50 kg (N) ha−1 were sprayed at 4 and 18 DAA. No yield increase or change in harvest index was observed either year by N, but seed protein concentration increased from 89 to 119 g kg−1 seed weight in 1983 and from 78 to 113 g kg−1 seed weight in 1984. In 1984, rates of hordein synthesis in seeds from N treated plots were 93, 38, and 40% higher than the control at 16, 22, and 35 DAA, respectively. Seeds from N treated plots contained 13 and 37% higher amino acids and 26 and 31% lower sugars than the control at 16 and 22 DAA, respectively. The elevated amino acids apparently favored the synthesis of seed protein that increased 27, 67, and 40% in the globulin and albumin, hordein, and glntelin fractions, respectively with LFAN. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) of hordeins revealed that hordein subunits were 33, 35.5, 38, 40.5, 42, 44, 50, 52, 54, 57, 61, 72, and 79 kD, and all increased by LFAN.
Relationship of Morphological Characteristics to Forage Quality in Quackgrass1
Authors: Greub L. J. , Collins M. , Carlson S. K. , Casler M. D.
Published: July 2010

The excellent adaptation of quackgrass [Elytrigia repens (L.) Nevski] in the North Central region of the USA suggests that this species may have potential as a cultivated forage. The objectives of this experiment were to characterize variation among quackgrass genotypes for in vitro dry matter disappearance (IVDMD), neutral detergent fiber (NDF), N, and several morphological characters and to determine whether quality and morphological characters were correlated. Thirty‐four genotypes of quackgrass, randomly collected in Wisconsin, were planted in four replicates on a Pillot silt loam soil (Typic Argiudoll). Vegetative growth was sampled from each genotype at the early heading stage of development in 1980, 1981, and 1982 and analyzed for IVDMD, NDF, and N. Genotypic variation averaged over years was significant for leafiness, leaf angle, leaf width, culm diameter, rhizome spreading vigor, growth habit, and all quality measurements except NDF. Genotype ✕ year interactions were significant for all characters except culm diameter and spreading vigor. Genotypic variation within years was significant for all characters in all years except for spreading vigor in 1980 and 1982, and IVDMD in 1982. Three‐year genotype means ranged from 645 to 731 g kg 1 for IVDMD, 555 to 609 g kg−1 for NDF, and 24.6 to 33.5 g kg−1 for N, and were significant except for NDF. Only growth habit was correlated with any quality character. The more prostrate plants were higher in N and IVDMD. It appears that sufficient genotypic variation exists within this population to improve IVDMD and N, and perhaps NDF. Morphology was not correlated well enough with quality in this study to be used in selection. Genotypes should be evaluated for quality for a minimum of 2 yr. Total N would be the best selection criterion among those investigated, due to its larger repeatability and lower genotype ✕ year interaction.
Recurrent Selection for Resistance to European Corn Borer in a Corn Synthetic and Correlated Effects on Agronomic Traits1
Authors: Klenke J. R. , Russell W. A. , Guthrie W. D.
Published: July 2010

The European corn borer (ECB) [Ostrinia nubilalis (Hübner)] is the most damaging corn (Zea mays L.) insect pest in the USA. Utilization of corn hybrids with reduced susceptibility to ECB is the most economical method of control. Iowa normally has two generations of ECB each season that coincide with two growth stages of the plant. Sources of resistance to both generations in one genotype are rare and additional sources are needed. Resistance to ECB is conditioned by several genes and is primarily additive in gene action. For these reasons, a 10‐line synthetic, designated BS9, was developed specifically to be used in a recurrent selection program. Four cycles of S1 recurrent selection were conducted for resistance to both first and second generation ECB, and these cycles were then evaluated to determine the extent to which resistance for the whole life of the plant could be improved. The four cycles of selection decreased ratings in BS9 from 3.6 to 2.7 for first generation ECB damage and from 6.4 to 4.4 for second generation ECB damage on a 1 to 9 scale, and cavity counts (one cavity = 2.5 cm) decreased from 8.9 to 3.1. High artificial infestations of first, second, and both generations of ECB resulted in average grain yield reductions of 5.7, 22.0, and 21.1%, respectively. An increase in resistance in advanced cycles of BS9 decreased yield reductions caused by artificial infestations of ECB. Yielding ability also decreased, however, resulting in no yield advantage of the more resistant material under high infestation levels. Yield reductions were not different between testcrosses of testers that varied in ECB resistance, which resulted in nonsignificant correlations between ECB damage ratings and yield. Tolerance may be the key factor in this response.
Reproduction at Low and Pollen Water Potentials in Maize1
Authors: Westgate Mark E. , Boyer John S.
Published: July 2010

Losses in grain yield are particularly severe when low water potentials (low ψW) occur at anthesis in maize (Zea mays L.). The losses can result from delays in floral development and from a failure in grain development when flowering appears normal. The causes of the latter problem are unknown, but could involve either the male or the female flower. Therefore, we made reciprocal crosses at various stigma (silk) and pollen ψW to determine which flower part failed at low ψW. The plants grew in soil in a controlled environment where silk ψW was between −0.3 and −0.5 MPa and pollen ψW between −1.5 and −12.5 MPa during the day. Water was withheld for a few days at anthesis after which water was resupplied and grain production was evaluated. At high pollen and silk ψW plants produced about 550 grains ear−1. At low pollen ψW (to −12.5 MPa), plants also produced grain at a similar high rate. However, at low silk ψW (−1.2 MPa), grain did not develop. The failure of the grain to grow could not be attributed to insufficient water on the silk surfaces because pollen germinated and the pollen tube grew within the silks. The egg sac invariably was fertilized but the embryo, endosperm, and seedcoat did not develop beyond 2 or 3 days. Therefore, the failure to produce grain at low ψW was attributed to factors in the female flower that allowed fertilization to occur but prevented embryo development. Because both embryonic and maternal tissues were involved, the effect suggests a general starvation for substrate, which could have been caused either by a lack of photosynthate or by a blockage of translocation. Earlier work from our laboratory showed that photosynthesis was inhibited at these ψW, and that carbohydrate reserves were low at this time. However, reserves accumulated at later stages of grain fill and could support grain growth when low ψW occurred. Therefore, a lack of photosynthate rather than a blockage of translocation may have caused the failure in grain development when low ψW were present at anthesis.
A Rapid Method for Evaluating Freezing Injury to Leaves of Cyanogenic Plants1
Authors: Stout Darryl G. , Brooke Barbara , van Ryswyk A. L.
Published: July 2010

Methods for simple and rapid evaluation of frost damage in plants are limited. A method to evaluate viability following freezing that is applicable to leaves of cyanogenic plants is described. The method involves the change of color of a paper disc impregnated with alkaline picrate from yellow to orange‐brown, owing to reaction with hydrogen cyanide (HCN) released from injured leaves. All leaves and leaflets of birdsfoot trefoil (Lotus corniculatus L., cv. Leo) released, HCN following freezing injury and had similar LD50 values. Leaves that will produce about the same amount of HCN can be obtained near the middle of a plant. Results obtained with this qualitative HCN test were similar to results obtained with existing tests of viability. The main advantages of this test are that it does not expose the plant material to an unnatural situation, and that it allows for more killing temperature measurements for a given labor investment.
Role of Assimilate and Carbon‐14 Photosynthate Partitioning in Soybean Reproductive Abortion1
Authors: Heitholt James J. , Egli D. B. , Leggett J. E. , MacKown C. T.
Published: July 2010

The yield production of soybean [Glycine max (L.) Merr.] is partly determined by the flower and pod abortion process. Since the causes of abortion are not well understood, field experiments were conducted over 2 yr to study the relationships of assimilate concentrations and photosynthate partitioning to flower and immature pod abortion. Soybean (cv. Kent) was grown in the field during two seasons using conventional cultural practices. Flowers that opened at R1 (early flowering) and R3 (late flowering) were marked and the abortion levels were determined. In the second year immature pods present just after early and late flowering were also marked and abortion determined. Flower and immature pad samples were taken on the day of marking for chemical analysis. Early flower abortion averaged 40%, and late flower abortion averaged 80%. Early immature pod abortion was 15Yo but late immature pod abortion was 57%. In both years the concentrations of ethanol‐soluble carbohydrates, starch, ethanol‐soluble N, ethanol‐insoluble N, NO−3, Mg2+, K+, and Ca2+ in the fully open flowers or in immature pods was not related to the abortion percentages exhibited by the flowers or pods. The ethanolsoluble carbohydrate concentration ranged from 71 to 107 g kg−1 in flowers and from 40 to 45 g kg−1 in immature pods. Starch concentration ranged from 24 to 29 g kg−1 in flowers and 18 to 30 g kg−1 in immature pods. The results did not support the hypothesis that low assimilate concentrations are the major cause of abortion in soybean. During both early and late flowering, a single leaf located in the middle of the main stem that subtended fully open flowers or immature pods was labeled with 14CO, at both 0 and 3 days after flower opening. Flowers exhibiting low abortion percentages contained a greater percentage of the total 14C recovered (0.049 to 0.095%) as well as a greater specific activity of 14C (0.018 to 0.027Yo mg−1 flower) than those exhibiting high abortion percentages (0.014 to 0.024% and 0.005 to 0.009% mg−1 flower, respectively). Immature pods exhibiting low abortion also contained greater percentages of 14C recovered (0.15 to 0.20%) than those exhibiting higher abortion (0.012%). Although it is difficult to distinguish between a cause and a symptom of abortion, abortion seems to be at least related to the lack of photosynthate partitioning to flowers and immature pods.
Barley vs. Oat Companion Crops. II. Influence on Alfalfa Persistence and Yield1
Authors: Brink G. E. , Marten G. C.
Published: July 2010

Recent evidence has indicated the superior quality of barley (Hordeum vulgare L.) forage compared to that of oats (Arena saliva L.). Evaluations of alfalfa (Medicago saliva L.) persistence following the seeding year are needed to determine the potential of barley vs. oats as a companion crop during alfalfa establishment. Our primary objective was to determine the influence of establishment with barley or oat companion crops harvested at four small grain crop maturation stages on alfalfa persistence overwinter and first crop yield the following spring. Four cultivars each of barley and oats were established with alfalfa at each of two locations during each of 2 yr and harvested initially at each of four small grain crop maturation stages. Alfalfa was also established alone (solo‐seeded) with and without herbicides and was harvested at first flower. Alfalfa persistence (proportion of complete ground cover) and subsequent yield of all treatments were determined in the spring following the seeding year. Alfalfa persistence and subsequent spring yield were usually not affected by harvest stage or small grain crop cultivar when the companion crop was harvested initially at the five leaf, flag leaf, or dough stages, even though barley cultivars frequently had greater potential for competition with the alfalfa at each stage than oat cultivars as measured by ground photography, leaf area index, and seedling alfalfa yield. Barley cultivars also lodged more frequently than oat cultivars. When the first establishment year harvest of the companion crops occurred at grain stage, alfalfa stands were often reduced more than when harvest occurred at immature stages. Persistence of alfalfa established when ‘Morex’ barley or ‘Lyon’ oats and harvested initially at flag leaf stage and then at first alfalfa flower was not different from that of solo‐seeded alfalfa established with or without herbicides and harvested twice at first flower. However, under the same management (but with a greater interval between seeding year harvests), the subsequent spring yield of solo‐seeded alfalfa was greater than that of alfalfa sown with Morex barley or Lyon oats in one year at both locations. We conclude that the barley cultivars tested in this study were as successfully utilized as oat cultivars during alfalfa establishment when the companion crop was harvested at immature stages. Although risk of alfalfa stand loss was greater following harvest of the companion crops at grain stage, the influence of barley and oat cultivars on alfalfa persistence at this stage was inconclusive and varied with the location and year.
Yield‐Maturity Relationship of Grain Sorghum in Diverse Environments1
Authors: Saeed Mohammad , Francis C. A.
Published: July 2010

Plant growth duration (maturity) is an important factor in development of yield in grain sorghum [Sorghum bicolor (L.) Moench]. The effects of genotype maturity on yield may vary among environments that differ in climatic factors such as temperature and photoperiod. A study was conducted to determine the relationship of grain yield with maturity of 46 sorghum hybrids evaluated in replicated field yield trials at several locations across Nebraska and Kansas in 1978 and 1979. The locations varied in day/night temperature and rate of growing degree unit (GDU) accumulation during the growing season, and multiple trials at a location were conducted with different agronomic treatments such as planting time (early, medium, late) and plant population (low, medium, high). Simple correlation coefficients were computed between yield and the number of days from planting to flowering and the number of days from flowering to physiological maturity (grain‐fill period) in each environment. A highly significant and positive correlation between yield and days to flowering was found in environments with relatively high night temperatures and high rate of GDU accumulation. This correlation, however, was significantly negative in cool environments with low night temperature and slow accumulation of GDU. Correlation of yield with the number of days in grain‐fill showed that longer grainfill periods generally favored high yields. This relation was especially found in cool environments with delayed maturity, where the majority of high yielding hybrids appeared to have compensated the yield reductions due to delayed flowering by prolonged grain‐fill period. We suggest that in such environments hybrids with early flowering and a long grain‐fill period would be desirable.
1985 United States Farm Maize Germplasm Base and Commercial Breeding Strategies1
Authors: Darrah L. L. , Zuber M. S.
Published: July 2010

Six surveys have been conducted, beginning in 1956, to determine the breadth of the U. S. maize (Zea mays L.) germplasm being commercially utilized and whether it is changing over time. The present survey was based on seed produced in 1984 available for planting in 1985. Twenty‐one public inbred lines were used as parents in hybrids in an amount that exceeded 0.1% of the total need each. Inbred B73 was used for 11.3% of the total 1985 seed requirements followed by A632 with 1.9%, W117 with 1.5%, Mo17 with 1.5%, and CM174 with 1.3%. All other lines occurred in less than 1% of the total requirement. Substantial decreases in public line usage were found in comparison with the 1979 survey. Hybrids using only private lines accounted for 62% of the total production. One or more public lines were included in 38% of the total production and one or more private lines were in 92% of the total production. The predominant source of new inbred line development was single crosses (20%), but 53% of the effort was identified as being from sources other than those specified in the survey questionnaire. Recycling of old elite inbred line families as sources of new lines declined from 1979. Significant effort, however, involved recycling within the B73, Oh43, and A632 inbred line families. Lines from 'Reid' germplasm were included as 44% of the total production in 1984, followed by ‘Iodent’ (24%) and ‘Lancaster’ (12%). Eighty‐eight percent of the seed produced included Reid germplasm because the reporting split production by parental component. Normal cytoplasm was used in 87% of the total production. The C‐type male‐sterile cytoplasm was used in 8% and the S‐type was used in 3% of the total production.
Recurrent Selection for 2n Pollen Formation in Red Clover1
Authors: Parrott W. A. , Smith R. R.
Published: July 2010

The superior quality and yielding ability of tetraploid red clover (Trifolium pratense L.) in Europe has led to interest in developing tetraploid red clover adapted to the USA. It is possible to use 2n gametes (gametes with the chromosome number of the sporophyte) to develop tetraploid red clover, but a relatively high frequency of 2n gamete production appears to be necessary before 2n gametes can be used efficiently to obtain tetraploid plants. Three cycles of phenotypic recurrent selection for 2n pollen production were conducted on adapted diploid red clover germplasm grown in the greenhouse. Average 2n pollen production per plant increased from 0.04% in the original population to 47.38% in the third cycle. In an effort to limit inbreeding, selection was restricted by families such that only the best plant from each family was selected. This appears to have been successful, as mean dry matter production per plant did not decrease during the selection process. Realized heritability for 2n pollen formation was about 0.50. It was estimated that two to six genes control the frequency of 2n pollen formation within a plant. After one cycle of selection the frequency of 2n pollen production was sufficiently high to successfully obtain tetraploid plants, although at a low frequency. After three cycles of selection against 2n pollen formation in a control population, we were unable to change the frequency of 2n pollen‐producing plants from that in the original population.
Identification of a Fourth Major Gene Conferring Resistance to Soybean Rust1
Authors: Hartwig Edgar E.
Published: July 2010

Studies were conducted in containment facilities at Frederick, MD to determine the genetic basis of resistance to Phakopsora pachyrhizi Syd. (incitant of soybean rust) carried by the soybean [Glycine max (L.) Merr.] line PI 459025. Previous studies showed that soybean genotypes PI 200492, PI 230970, and PI 462312 each carried a single dominant gene conferring resistance to a specific soybean rust isolate. Genotype PI 200492 gave a near‐immune reaction to rust isolate India 73‐1 and a susceptible reaction to Taiwan 72‐1. Genotype PI 462312 gave a resistant reaction to the India rust isolate and a susceptible reaction to the Taiwan isolate. Genotype PI 230970 and F4 lines having PI 230970 as a parent gave resistant reactions to both rust isolates. Genotype PI 200492, PI 230970, and PI 462312 gave a susceptible reaction when inoculated with rust isolate Taiwan 80‐2. Line PI 459025 was identified as resistant to Taiwan 80‐2 as well as Taiwan 72‐1 and India 73‐1. Line PI 459025 was crossed with each of the three previously identified sources of resistance. The F1 plants, F2 populations, and selected F3 lines were inoculated with each of the three rust isolates to determine their reaction. For each plant evaluated, a leaflet of a single trifoliolate leaf was inoculated with a different rust isolate. The results showed that PI 459025 carried a single dominant gene for resistance to all three rust isolates and that this gene was at a different locus from the three previously identified genes conferring resistance to specific rust isolates. The genotype assigned for rust resistance of PI 459025 is rpp1 rpp1 rpp2 rpp2 rpp3 rpp3 Rpp4 Rpp4.
Tritordeum: A New Alloploid of Potential Importance as a Protein Source Crop1
Authors: Cubero J. I. , Martin A. , Millán T. , Gómez‐Cabrera A. , de Haro A.
Published: July 2010

Promising allohexaploids derived from macaroni wheat (Triticum turgidum conv. durum Desf. em. M.K.) ✕ a wild barley (Hordeum chilense Roem. et Schulz.), named tritordeum were produced. Primary tritordeums have small, but well filled, plump seeds. They have been field tested for 5 y (sixth and seventh generations) after chromosome doubling. Compared with advanced bread wheat (T. aestivum L. em. Thell.), tritordeums yielded 20 to 40% of the average wheat yield. Tritordeum matures later, is shorter, and has more spikelets per spike than its wheat parent. Protein content (17.6 to 25.2% on dry matter basis) is consistently higher than that of wheat and triticale (X Triticosecale Wittmack). In regard to other nutritional characteristics, such as in vitro digestibility, neutral and acid detergent fiber, lignin, cellulose, hemicellulose, ether extract, N free extract, and amino acid profile, tritordeum is similar to other cultivated cereals.
Effect of Seeding Date, Plant Density, Moisture Availability, and Soil Nitrogen Fertility on Maize Kernel Breakage Susceptibility1
Authors: Bauer P. J. , Carter P. R.
Published: July 2010

The objectives of this study were to evaluate seeding date, plant density, moisture availability, and soil N fertility effects on maize (Zea mays L.) kernel breakage susceptibility. Three hybrids within each of three relative maturity (RM) groups (90, 100, 110 days by Minnesota Relative Maturity Rating System) were grown in separate seeding date and plant density studies at Arlington, WI [Plano silt loam (fine‐silty, mixed, mesic, Typic Argiudoll)], in 1983 and 1984. Maize was seeded four times at 10‐day intervals beginning 1 May. Average densities were 1.75,3.75,5.75, and 7.75 plants m−2. Hybrids were also evaluated in separate irrigated and dryland trials at Hancock, WI [Plainfield sandy loam (mixed, mesic, Typic Udipsamment)]. In a soil N study, grain samples were collected from an experiment at Arlington in which three N rates (0,11, and 22 g m−2 were applied. Grain was combine‐harvested at 25% kernel moisture (except at Hancock where moistures ranged from 21 to 32%) and dried at 82°C in 1983 and 60°C in 1984. Kernel breakage susceptibility, test weight and kernel weight, volume, density, and grain yield were measured. Delayed planting, high plant densities, and low applied N increased kernel breakage susceptibility. At Hancock, higher kernel breakage susceptibility occurred with irrigated‐ vs. dryland‐produced maize. Kernel physical parameters measured were not closely related to kernel breakage susceptibility, except in the soil N study, where the largest range occurred for each variable. The 110‐day RM hybrids had lower kernel breakage susceptibility than 90‐ and 100‐day RM hybrids.
Transformation of Cultivated Alfalfa Using Disarmed Agrobacterium tumefaciens1
Authors: Shahin Elias A. , Spielmann Albert , Sukhapinda Kitisri , Simpson Robert B. , Yashar Mayer
Published: July 2010

This study was conducted to establish a transformation system for cultivated alfalfa (Medicago sativa L.), a highly valued forage legume. Genetic transformation of alfalfa ‘CUF101’ was carried out using Agrobacterium tumefaciens. A dominant selectable marker (Nos/ Npt) for kanamyycin resistance was introduced into alfalfa tissues via a disarmed vector (pARC8) residing in the bacterium. The Nos/ Npt gene was stably integrated into the plant genome and expressed in selected, kanamycin‐resistant calli and in regenerated plants. Transgenic alfalfa plants were also obtained using two different vectors derived from pARC8.
Mapping Three Protein Loci on a Soybean Chromosome1
Authors: Kiang Y. T.
Published: July 2010

Recombination frequencies between pairs of three protein loci on Linkage Group 9 in soybean [Glycine max (L.) Merr.] were determined so that they could be mapped. ‘Earlyana’, ‘Ebony’, ‘Hakucho’, ‘Jefferson’, ‘Kingwa’, and ‘Wilson’ were intercrossed and the F2 segregation frequencies of the markers were used to calculate map distance among the acid phosphatase (Ap), leucine aminopeptidase (Lapl), and trypsin inhibitor (Ti) loci. The recombination frequency between Ap and Lapl was estimated as 23.6 ± 1.0%. The recombination frequency between Ap and Ti was estimated at 6.6 ± 0.5%, which is significantly different from 16.2 ± 1.5% reported previously. The map distance between the Lapl and Ti loci was calculated to be 16.3 ± 1.0 map units. The three loci in Linkage Group 9 were mapped on the basis of the recombination values obtained in this study. The order of the three loci is Ap‐Ti‐Lapl.