bluuebunny/crossref_metadata_2025 huggingface dataset:
Harvest Indexes of Backcross‐Derived Wheat Lines Differing in Culm Height1
Authors: Allan R. E.
Published: July 2010

The high grain yields of some short‐statured small grain cultivars have been ascribed to their improved harvest index (HI) values. This study determined the influence of genetic backgrounds and genes (Rht1, and Rht2) for semidwarf culm height on HI of wheat (Triticum aestivum L.). The HI was measured in four tests on progeny of seven backcross‐derived populations (six backgrounds). The progeny consisted of three culm height classes designated as two‐gene semidwarf(short), one‐gene semidwarf(medium)a, nd normal( tall). Lines with Rht1 or Rht2 genes either singly or in combination had significantly higher HI values than their normal (nonsemidwarf)sibs in 45 of 56 comparisons. Short two‐gene semidwarf lines had significantly higher HI values than their one‐gene and normal counterparts in 9 of 28 and 25 of 28 comparisons, respectively. One‐gene semidwarf lines exceeded HI values of their normal sibs for 20 of 28 comparisons. When calculated across tests and populations, the HI means of two‐gene semidwarf, one‐gene semidwarf, and normal lines were 41.4, 38.0 and 31.6, respectively. The two‐ and one‐gene semidwarf doses increased HI by 31 and 20%,r espectively. The HI values of the inherently taller backgrounds were increased proportionately more than shorter backgrounds by addition of one or two doses of semidwarf genes. The HI of the ‘Marfed’ background was increased most by addition of the Rhtl and Rht2 genes. Based on simple correlations, the use of HI as a selection criterion for grain yield appeared more feasible among inherently taller than shorter backgrounds. Because all interactions among tests, populations and height classes were significant, selection for greater HI may be tenuous.
Inheritance of a Micro Phenotype in Peanut1
Authors: Branch W. D. , Hammons R. O.
Published: July 2010

A miniature phenotype found in peanut(Arachis hypogaea L. ‘Tennesse Red’), which has significantly reduced vegetative and reproductive characteristics, was investigated to determine the mode of inheritance. Three distinct classes resulted from selfing the miniature class: micro, a form with extreme reduction in stems and leaves; miniature (mini), plants with general reduction in all organs; and normal. The F1 and F2 data from a complete diallel crossing study indicated monogenic inheritance with partial dominance for micro phenotype. The gene symbol Mi is proposed for the allele involved in the expression of the micro and mini plants.
Inheritance of Resistance to Infection by Drechslera Sorokiniana in Tall Fescue1
Authors: Linscombe S. D. , Watson C. E. , Trevathan L. E.
Published: July 2010

Drechslera sorokiniana (Sacc.) Subram. & Jain (= Helminthosporium sativum P.B.&K.) is a major pathogen of tall fescue (Festuca arundinacea Schreb.). Damage to infected plants can vary from a small number of minute spots on the leaves to extensive coalescing lesions which can eventually kill highly susceptible plants. The objectives of this study were to examine the inheritance of resistance to infection by D. sorokiniana in tall fescue and to determine the effects of selection for resistance using a greenhouse inoculation technique. In Exp. 1, a five parent (Diallel I) and a six parent diallel cross (Diallel II) were evaluated for resistance to infection by D. sorokiniana. Variation for general combining ability was significant for lesion coverage and lesion size in both diallel crosses. Specific combining ability variation was not significant. In most cases, highly resistant ✕ highly resistant crosses had high levels of resistance, highly susceptible ✕ highly susceptible crosses had low levels of resistance and highly resistant ✕ highly susceptible crosses had intermediate levels of resistance. In Exp. 2 ‘Alta’, ‘Kentucky 31’, MSF‐72‐1, and Oregon 1000 tall fescue were subjected to a single cycle of mass selection for resistance to infection by D. sorokiniana. Resistance as measured by lesion coverage and lesion size was significantly increased in all populations. Heritability values ranged from 0.62 (Alta) to 0.78 (Oregon 1000) for lesion coverage from 0.38 (Alta) to 0.69 (Oregon 1000) for lesion size. Results from both experiments suggest that additive gene action is of major importance in the control of resistance to infection by D. sorokiniana. Mass selection is an efficient means of improving the level of resistance.
Mobilization of 15N from Soybean Leaves as Influenced by Rhizobial Strains1
Authors: Morris Dolen R. , Weaver W.
Published: July 2010

Nitrogen nutrition of soybeans [Glycine max (L.) Merr.] during pod development is important in determining seed yield. Soybeans utilize leaf N to meet the N needs of developing fruit which may reduce yield potential. A field experiment was undertaken using 15N to test the hypothesis that high N2‐fixing rhizobia would delay mobilization of N from leaves to developing pods. Three strains of Rhizobium japonicum, USDA strains 110, 31, and an ineffective mutant of strain 8‐0, varying in N2‐fixation effectiveness were used as inoculum to determine their influence on the utilization and translocation of N during pod fill. Foliarly applied 15N urea was sprayed onto leaves five times prior to pod formation to label vegetative N. Total application of N was approximately 3 kg/ha. During the first 17 days of pod development approximately 25% of the incorporated 15N was mobilized to the pods regardless of the rhizobial strain. During the final stages of pod development, mobilization of labelled N continued at nearly a linear rate for all rhizobial treatments. for USDA strain 110, there was an insignificant net loss in leaf and petiole N during the first 17 days of pod development which indicated there was an exchange between N2 recently fixed and N previously incorporated into leaves. The rate of N2‐fixation by both effective strains of rhizobia increased during pod development. Even though strain 110 fixed more total N than strain 31 the final seed yield for both treatments was similar due to differential partitioning of N. Future research is needed to elucidate the partitioning of N2 fixed during pod development and to determine why the better N status of plants inoculated by strain 110 did not result in increased yields.
Variation of Cottonseed Quality With Stratified Harvests1
Authors: Kohel R. J. , Cherry J. P.
Published: July 2010

Selected constituents of mature cottonseed harvested at weekly intervals (up to 6 weeks) from opened bolls of seven entries were measured during 2 crop years (1976, 1979). The seed were analyzed for weight, oil, protein, gossypol, and selected fatty acids and amino acids. Major weather differences between years during the periods of flowering and seed maturity caused variations in seed composition. Part of these variations was probably due to weather conditions that affected cottonseed development and differentiation, and energy demands within the cotton plants as the growing seasons progressed. Seed weights decreased, oil and free gossypol percentages declined and proteins increased with progressively later harvest dates during the 2 crop years. In oil, palmitic acid percentages decreased with later harvest dates during both crop years, and oleic and linoleic acid values were variable between seasons and over harvest dates, but these fatty acids followed a consistent reciprocal relationship. The percentages of amino acids in proteins including lysine, threonine, isoleucine, methionine, and half‐cystine increased during later harvest dates in 1976. Positive correlations for all amino acids and harvest dates were noted, but these values were significant only for total amino acids (similar to total protein), lysine, and methionine. The amount of oil and protein in seed decreased with harvest date, but the greatest change was in the amount of oil. These data provide information on the variation of the composition within and between crop years, and they indicate the need for additional research on factors contributing to variation in cottonseed composition.
Accumulation of Pyrrolizidine Alkaloids in Benomyl‐Treated Tall Fescue Parents and their Untreated Progenies1
Authors: Jones T. A. , Buckner R. C. , Burrus P. B. , Bush L. P.
Published: July 2010

Both pyrrolizidine alkaloids (N‐formyl loline and N‐acetyl loline) and the seed‐transmitted endophytic fungus tentatively identified as Sphacelia typhina (Pers.) Sacc. (=Acremonium coenophialum Morgan‐Jones and W. Gams), the imperfect stage of Epichloe typhina (Fr.) Tul., have been suspected as etiological agents of summer syndrome. Summer syndrome is a toxicological disorder exhibited by cattle grazing tall fescue (Festuca arundinacea Schreb.) under high ambient temperatures. The primary objective of this study was to investigate the relationship between content of N‐formyl and N‐acetyl loline alkaloids (FALA) and the presence of the endophyte, summer forage yield, moisture content, and acid‐detergent fiber in the field. The presence of the endophyte was determined cytologically and FALA were quantified by gas‐liquid chromatography. The endophyte was controlled by soil treatment of parent plants in the greenhouse with the systemic fungicide benomyl. Polycross progeny seed were collected and grown out for comparison with parents. Though the endophyte was not eradicated by benomyl, in many parents benomyl impeded infection of the seed, thus reducing transmission of the endophyte to its progenies. In progenies with a lesser degree of endophyte infection than their parents, FALA content of summer forage and seed was likewise lower. These data indicate an association between the endophyte and accumulation of FALA. Correlation coefficients between FALA and summer forage yield, moisture content, and acid‐detergent fiber were low, suggesting that selection for FALA would not likely result in correlated responses for these traits. In a follow‐up greenhouse experiment, the endophyte and FALA were lost in several plants from one progeny line, indicating that the endophyte and FALA accumulation capacity can be inhibited or eliminated in established plants. Since only one progeny line was involved, this effect may be genotype dependent.
Differences in the Embryo‐Specific Globulins among Maize Inbred Lines and Their Hybrids1
Authors: Cross John W. , Adams Whitney R.
Published: July 2010

The subunit composition of the major seed embryo globulins of corn (Zea mays L.) was studied in a series of inbred lines and their hybrids. Polypeptides of molecular weight (in kilodaltons kD) of 65, 50, 30, 29, and 21 kD were common to all inbred: and hybrids examined. Certain genotypes contained additional polypeptides. For instance, embryos of Mo17 contained a 58 kD polypeptide not found in B73, and embryos of B73 contained a 42 kD polypeptide not found in Mo17. The hybrid B73 ✕ Mo17 contained both of these polypeptides. These results suggest the pattern of embryo globulin peptides is distinctive in a particular inbred line and could be employed as part of a test for identity.
Relationship Between Genetic Distance and Heterosis for Yield and Morphological Traits in Dry Edible Bean and Faba Bean1
Authors: Ghaderi A. , Adams M. W. , Nassib A. M.
Published: July 2010

The association of genetic distance and heterosis was investigated in dry edible bean (Phaseolus vulgaris L.) and faba bean (Viciafaba L.). Dry bean materials consisted of 28 F2 populations of an 8 × 8 diallel, and their respective parents, grown in eight replications in the field at East Lansing, Mich. in 1981. Faba bean materials comprised the 64 F1's and parents of an 8 × 8 diallel grown in 1975, and 120 populations grown in 1976 como prised of F1's, F2's, and parents of the same diallel, grown in four replications at the Agricultural Research Center at Giza, Egypt. Mahalanobis' D2 was used to estimate genetic distance between parents. Heterosis was measured as deviation from midparent. Correlations in dry beans between heterotic effects and parental distances were positive and highly significant for yield at harvest and for two of the three yield components, namely, number pods/plant and number seeds/pod. No relationship was found for 100‐seed weight. A highly significant positive correlation was obtained for leaf weight. Both significantly positive and negative correlations were found in faba beans for an array of “number” traits related to yield, but heterosis for yield of seed per se in faba beans was not associated with the Mahalanobis D2's
An Adaptive Response of Rye to Freezing1
Authors: Olien C. R.
Published: July 2010

An increase in intercellular solute of crown tissue was induced by keeping hardened plants frozen at −3°C for 24 h. This environmental condition commonly occurs because of temperature stabilization from latent heat released as soil water freezes. The amount of intercellular solute in crown tissues was estimated from the concentration of liquid that, when perfused through the plant crown at 1°C, was found, by successive approximations, to be isotonic with the intercellular liquid. The intercellular content of ‘Rosen’ rye (Secale cereale L.) increased by factor of 3.0 to 3.5 when frozen 24 h at −3°C; then at 1°C, the concentration gradually decreased to that of nonfrozen plants. Recovery occurred in less than 1 h at 25°C. The increase of intercellular solute content occurred as a function of time at −3°C. ‘Hudson’ barley (Hordeum vulgare L.) which contains less intercellular solute than Rosen rye after freezing at −3°C, and Rosen rye in which the intercellular solute was reduced by flushing, were less hardy than Rosen rye tested with the normal 24‐h prefreeze at −3°C.
Water Stress Status in Guayule as Measured by Relative Leaf Water Content1
Authors: Ehrler W. L. , Nakayama F. S.
Published: July 2010

The relative leaf water content (RLWC), defined as the ratio of leaf water content at sampling to that at full turgor, was observed to be a sensitive indicator of soil water deficits for two cultivars of guayule (Parthenium argentatum Gray) in an experiment at Phoenix, Ariz. A year's measurements showed highly significant correlation coefficient values for the linear regression of RLWC on the amount of water in the soil (ram water/170‐cm depth of soil). The r values ranged from 0.93 in the dry treatmento 0.78 in the wet treatment of cv. 593, which consistently depleted the soil moisture to lower values than 11591. The RLWC decreased to extremely low values, 30 to 40%, but irrigation restored them to about 75% overnight, accompanied by a gain in leaf area of as much as 30%. The RLWC technique does not require elaborate instrumentation or procedure and may be useful as a guide to irrigation scheduling of guayule.
Transmission of Nematode Resistance in the Pedigree of Homozygous Resistant Sugarbeet1
Authors: Yu M. H.
Published: July 2010

Transmission of resistance to the cyst nematode (Heterodera schachtii Schmidt) in the pedigree of a homozygous resistant sugarbeet (Beta vulgaris L.) was studied with the aid of test parents containing either a red hypocotyl marker or male‐sterility. The results indicated that virtually all megaspores and microspores produced from the resistant homozygotes carried resistance to their resultant progeny. However, resistance transmission was less than complete in succeeding generations, being 97.5% through eggs and 95.7% through pollen of the S2 plants of sugarbeet line 3584. These results indicate that nematode resistance may be lost from a homozygous resistant sugarbeet line, although only at a low rate. Therefore, future sugarbeet hybrid cultivars should be developed from an early generation of a resistant homozygote to maintain the highest level of nematode resistance. No close linkage between the loci for hypocotyl color and nematode resistance was detected.
Breeding Apomictic Lovegrasses: Forage Potential of Boer ✕ Weeping Hybrids1
Authors: Voigt P. W.
Published: July 2010

Breeding schemes have been developed for several apomictic species. However, few assessments of the potential of hybrids developed through manipulation of apomixis have been published. Apomictic lovegrass Eragrostis curvula (Schrad.) Nees, hybrids were developed from crosses of sexual boer ✕ apomictic weeping lovegrass. The objectives of this research were to determine the forage potential of boer ✕ weeping hybrids, assess the genetic potential of the parent genotypes, and begin to evaluate the usefulness of the apomictic breeding scheme. Significant differences in forage vigor and quality were found among the hybrids. ‘Morpa’ weeping lovegrass produced hybrids that were higher in in vitro dry matter disappearance (IVDMD) than common weeping lovegrass hybrids. Boer lovegrass genotype 40‐9‐69FQ (40‐9) was inferior as a female parent because its hybrids tended to be lower in vigor than those from other boer lovegrass genotypes. Several hybrids from the cross 40‐9 ✕ Morpa were significantly higher in IVDMD than Morpa or ‘Ermelo’, the most digestible cultivars. However, IVDMD and vigor were negatively related in that cross (r = ‐0.31 to ‐0.72**, significant at the 0.01 level of probability). Two hybrids with superior IVDMD and average vigor were identified. Diplosporic apomixis can be successfully manipulated to develop higher quality lovegrass cultivars if the negative relationship between IVDMD and vigor can be broken or is found to be less important in other crosses.
Quantification of Infection Levels in Wheat Genotypes Varying in Stem Rust Resistance1
Authors: Eaton D. L. , McVey D. V. , Busch R. H.
Published: July 2010

Stem rust (Puccinia graminis f. sp. tritici) development was studied in six F3‐derived F3 wheat (Triticum aestivum L.) lines selected from a cross of ‘Era’ (stem rust resistant) and ‘Morocco’ (stem rust susceptible). In previous tests for susceptiblity to stem rust race 15‐B(TLM), two of the lines had been classified as slowrusting, two as moderate‐rusting, and two as fast‐rusting. The objectives of the present study were to: 1) evaluate the relationship between field measurements of stem rust resistance and grain yield and kernel weight using infected lines vs. protected controls and 2) measure stem rust development in the greenhouse at two growth stages (boot and milk) to predict field response to stem rust from greenhouse measurements. Race 15B‐2(TLM) was used to inoculate all entries to measure stem rust development. Stem rust development curves (AUSRC) were calculated from percent rust on the flag leaf sheath in field plots and from number of pustules/top 10 cm of leaf sheath below the flag leaf in the greenhouse. Latent period was measured in the field and greenhouse as the number of days from inoculation to first appearance of pustules. Differential yield and 200 kernel weight reductions among protected and rusted treatments and the AUSRC differences were effective in distinguishing which lines were slow‐rusting in the field. Latent period, initial infection level, and rate of increase in AUSRC were the most important stem rust variables affecting final infection level. An overall ranking system composed of percent reductions in yield and kernel weight and values for the three stem rust variables indicated only two lines (one slow‐, one fast‐rusting) retained their original classifications. Of the two originally classified moderate‐rusting lines, one reacted as fast‐rusting and one as slow‐rusting. One of the slow‐ and one of the fast‐rusting lines reacted as moderate‐rusting lines. In the greenhouse, plants in both the boot and milk growth stages reacted similarly to stem rust infection. Final pustule numbers on the leaf sheath was the best measurement of stem rust severity. Prediction of field infection level using greenhouse variables was not possible.
Ultrastructure of Cell Wall Degradation in Panicum Species Differing in Digestibility1
Authors: Akin Danny E. , Rigsby Luanne L. , Brown Harold R.
Published: July 2010

The genus Panicum has been shown to have species exhibiting a range of leaf digestibility. Leaf anatomy as well as differences in degradation of specific tissues have been implicated as factors influencing the digestibility. The objective of the present report was to examine microscopically specific cell wall types in leaves of upper and lower nodes for the pattern of attack and the microorganisms involved in cell wall degradation in Panicum species having different digestibilities. Lignified tissues (i.e., sclerenchyma and vascular tissue) were the most resistant, with xylem cells essentially not degraded and sclerenchyma cells degraded at the periphery. Mesophyll cells displayed a range in digestibility; bacteria did not adhere to the cells. The mesophyll in bottom lamina tended to be more rapidly degraded than in upper lamina of P. milioides Nees ex Trin. and P. laxum Sw. whereas differences were not observed between upper and lower lamina in other species. Epidermal cells were usually degraded after adherence by bacteria, which formed clearly defined zones of erosion in cell walls and separated the intact cuticle from the blades. However, cell walls of P. tricanthum often showed zones of erosion without adhering types of bacteria. Bundle sheath cells of C4 species were degraded mostly by adhering types of bacteria, with a thin electron dense layer often resisting digestion. Sheath cells in P. milioides and P. tricanthum were totally degraded. Two distinct morphotypes of bacteria, i.e., encapsulated cocci and irregularly‐shaped bacteria, were the predominant ones that adhered to and attacked the more slowly degraded tissues. Easily degraded cells were degraded by nonadhering microorganisms. Results indicated that differences existed in the manner of attack on plant cell walls by rumen bacteria and that these differences were reflected in variation in the ease of digestion.
Tillering Dynamics of Water Barley as Influenced by Cultivar and Nitrogen Fertilizer: A Field Study1
Authors: García del Moral L. F. , Ramos J. M. , Recalde L.
Published: July 2010

A thorough knowledge of tiller development is essential in the analysis of grain production in most cultivated cereals, since the final number of ears produced by these plants is dependent on tillering. The object of this study was to investigate, under field conditions, the pattern of tillering, ear production, and survival of the component tillers in six barley cultivars: four six‐rowed (Hordeum vulgare L.) and two two‐rowed (H. distichon L.). The cultivars were grown in Granada, Spain, during 1980 and 1981 on a fine‐loamy, carbonatic, thermic, Calcixerollic Xerocrept soil, and each was subjected to two levels of N fertilizer(25 and 40 kg ha‐1), both at seeding and as a top‐dressing. From the data collected on tiller development during this study, the existence of a critical survival height for tillers is postulated: tillers less than one‐third the height of the main stem at the end of shooting would fail to produce ears. The end of shooting corresponds to stages 8 and 9 of Feekes' scale when the last leaf or the ligule of the last leaf, respectively, is just visible. Nitrogen treatments at seeding, when added at maximum dosage, increased significantly both the number of tillers at the end of shooting (maximum increase = 21%) and the final number of tillers with ears (maximum increase = 31%), while the N treatments at topdressing (midway during shooting) did not affect the number of tillers at the end of shooting or at harvest.
Technique for Crossing Proso Millet1
Authors: Nelson L. A.
Published: July 2010

Controlled crosses are needed to exploit the genetic potential of proso millet (Panicum miliaceum L.). Techniques used for other self‐pollinated crops resulted in low seed set. The small florets with tightly held lemma and palea make emasculation difficult prior to anthesis. In this technique the florets are mechanically stimulated by rubbing and warming them between 0800 and 0900 prior to their opening naturally. The anthers are either removed immediately or are kept moist by misting with water until they can be removed. Emasculated florets are then pollinated and a glassine bag placed on the panicle. Ten to 15 min are required to produce 2 to 5 F1 seeds. This technique yields about 80% cross‐pollinated seeds.
Year Effects on Partitioning of Dry Matter into Cotton Boll Components1
Authors: Kohel R. J. , Benedict C. R.
Published: July 2010

The distribution of dry weight in cotton boll walls, seeds, and fibers was investigated through the boll developmental period for one flowering date each year in 1979 and 1980. Previous experiments on patterns of fiber development encountered large environmental variation, so this experiment with four diverse cottons was undertaken to measure the effect of years on dry weight distribution into boll components. There was a large difference between years in temperature and moisture, with 1980 being hot and dry. Associated with differences in weather between the years was a large difference in dry weight distribution and boll development. In 1980, cotton matured in 88% of the time, individual boll dry weight was reduced 25%, boll wall dry weight per boll was reduced 17%, seed dry weight per boll was reduced 15%, and fiber dry weight per boll was reduced 41% compared to 1979. In addition, bolls developed in 1980 had fewer but larger seeds and fewer but larger fibers than in 1979. Total lint yield was reduced only 7% in 1980 vs. 1979, so more bolls were produced in 1980. At the individual boll level, the differences between years had the greatest effect on fiber dry weight. The effect on fiber dry weight per boll demonstrated the vulnerability of fiber development to environmental variation.
Screening and Characterizing Alfalfa for Persistence under Mowing and Continuous Grazing1
Authors: Counce P. A. , Bouton J. H. , Brown R. H.
Published: July 2010

Alfalfa (Medicago sativa L.) is a high quality forage species that does not persist well under frequent, intense defoliation such as continuous grazing. Experiments were performed to screen alfalfa cultivars for persistence under mowing and continuous grazing and to identify plant characters that may be associted with persistence. Twenty‐two alfalfa cultivars were grazed continuously for 100 days in each of 3 years to a height of 3 to 5 cm, and mowed infrequently in a nearby area during the same period. Cultivars did not differ significantly for persistence under mowing, but did under grazing. Persistence of cultivars under mowing and under grazing was not correlated. Persistent and nonpersistent cuitivars were subsequently examined for differences in topgrowth and carbohydrate utilization. Topgrowth and total nonstructural carbohydrates in the taproots were less for persistent cultivars than nonpersistent cultivars. Persistent cultivars appeared to depend less on taproot carbohydrates for initial topgrowth than nonpersistent cultivars. The prospects for selecting alfalfa for persistence under grazing are promising, but such selection could possibly lead to less productive alfalfa lines unless care is taken to insure productivity as well as persistence.
Effect of Temperature and Sucrose Availability on Kernel Black Layer Development in Maize1
Authors: Afuakwa J. J. , Crookston R. Kent , Jones R. J.
Published: July 2010

The objective of this study was to investigate the cause of black layer formation in maize (Zea mays L.). Four hybrids were field‐grown and defoliated at different stages of kernel maturity to determine the effect of assimilate supply reduction on black layer formation. Kernels from a fifth hybrid were cultured in vitro to determine the effect of temperature and scurose availability on black layer formation. Black layer formed in maize kernels independent of any specific environmental condition, and was not coincident with any particular physical state of the kernel. Black layer was observed in kernels ranging from 23 to 76% moisture. Kernel size at black layer ranged from 45 to 312 mg. Time from silking to black layer formation ranged from 29 to 78 days. Accumulated heat units from pollination to black layer ranged from 532 to 937. It appeared that a reduction in, or termination of, the supply of sucrose to the kernel induced black layer formation in maize. Premature formation of black layer following cold temperatures, drought or defoliation might all be explained on the basis of reduced sucrose availability.
Cessation of Leaf Emergence in Indeterminate Soybeans
Authors: Sinclair T. R.
Published: July 2010

Cessation of leaf emergence in indeterminate soybean [Glycine max (L.) Merr.] cultivars has not been characterized. Variation in ontogeny within cultivars was induced in field‐grown soybeans to study cessation of leaf emergence. Tungsten‐halogen lamps were used to extend the photoperiod to 14.5 h and to produce an illuminance gradient in field plots to induce a variation. In 1980 plant development was alteredin all 21 cultivars studied, with the greatest response occurring for ‘Peking’ with the maturity date delayed 69 days and node number increased by 16. In 1982 detailed observations of leaf emergence and plant ontogeny of 5 cultivars showed that the initiation of reproductive growth had no influence on the rate of leaf emergence on the main stem in indeterminate cultivars. The rate of leaf emergence remained constant until it ceased abruptly. The date of cessation of leaf emergence occurred from 2 to 10 days prior to stage RS. A more accurate characterization of plant ontogeny at the cessation of leaf emergence was the appearance of a pod 5mm long or greater at the node above the topmost node with a terminal leaflet 8 mm or longer.
Inheritance of Delayed Leaf Senescence in Soybean1
Authors: Pierce Robert O. , Knowles P. F. , Phillips Donald
Published: July 2010

Inheritance studies of the delayed leaf senescence phenotype (DLS) in soybean, Glycine max (L.) Merr. were conducted in field environments over a 4‐year period. Studies of F2 and F3 generations from the ‘Lee 68’ ✕ ‘L63‐1097’ cross indicated that two major genes, probably Dt1,dt1, affecting growth habit, and E1,e1, affecting flowering date, were involved, with the genotype dt1dt1e1e1 having the DLS phenotype. Selected lines in the F6 generation that showed uniform DLS traits were crossed to ‘Amsoy 71’, ‘Elf’, ‘Evans’, ‘Harosoy L2’, and ‘Williams’. Segregation ratios in the F2 and F3 generations from crosses involving Amsoy 71, Harosoy L2, and Williams indicated that a single major gene, assumed to be Dt1,dt1, was involved in DLS expression. Studies with Harosoy L2 and ‘Clark LI’ isolines of known genotype at the Dt1,dt1, Dt2,dt2, E1,e1, and E2,e2 loci showed that the DLS phenotype was expressed fully only when the dt1dt1dt2dt2e1e1e2e2 genotype was present. Observations of F2 populations and F3 lines of crosses involving DLS lines and Elf, both of which have the dt1dt1e1e1 genotype, indicated that differences between the parents were due to an undetermined number of modifier genes with small effects. Results from crosses involving DLS lines and Evans were inconclusive.
Delayed Leaf Senescence in Soybean1
Authors: Phillips Donald A. , Pierce Robert O. , Edie Scott A. , Foster Ken A. , Knowles Paulden F.
Published: July 2010

Leaves of commercial soybeans [Glycine max (L.) Merr.] typically senesce and abscise during seed development, but certain genetic lines produce mature seeds and show a delayed leaf senescence (DLS) phenotype in which leaves remain green until killed by frost. Field studies with such DLS lines provide information on the physiological and agronomic traits associated with such plants. Acetylene reduction and carbon exchange rates of DLS plants declined greatly after seeds matured, but positive values were measured until frost. Leaves formed before flowering which remained on DLS plants at the R8 stage had significantly (P ≤ 0.01) higher concentrations of reduced N and starch than those measured in leaves of normal plants just prior to abscission. In addition, a new population of axillary leaves containing substantial N and starch often developed during pod filling in DLS lines. The highest seed yield measured in DLS materials was 2370 kg/ha, which was 75 and 86% of the yields recorded in plots of ‘Elf’ and ‘Clark’, respectively. The highest yielding DLS lines accumulated as much N as Elf under conditions where both entries obtained about 75% of their N from N2. Progeny row studies of the DLS trait in two different genetic backgrounds showed significant (P ≤ 0.001) negative correlations between seed yield and the DLS phenotype. Reciprocal shoot/root grafts between Clark and DLS plants established that the DLS trait was controlled by the shoot genotype. It is concluded that expression of the DLS trait does not require severe inhibitions of reproductive development, such as is associated with male sterility. However, in the materials used in this study, the DLS phenotype was associated with a decrease in seed yield.
Isolation of Genetic Male Sterile Mutants in a Semidwarf Japonica Rice Cultivar1
Authors: Mese M. D. , Azzini L. E. , Rutger J. N.
Published: July 2010

Genetic male sterility was induced in the semidwarfjaponica rice (Oryza sativa L.) cultivar M‐101 by treatment of seeds with 30 kR of gamma rays. In the X2 generation, 251 partially sterile plants which presumably were true steriles that were setting seed due to outcrossing, were selected and designated as Group I lines. Fertile progenies of these X2 plants were considered to beputative Fl's from natural crosses. By a series of progeny tests, which eventually involved confirmed crosses, eight lines which carried single recessive genes for male sterility were derived from these putative F1's. In the X2 generation 18 completely sterile plants, designated Group II lines, also were selected. One single‐gene, recessively‐inherited genetic male sterile was derived from these 18 lines. Seed set on the male steriles from open pollination by sib plants ranged from 12 to 40% on the eight final Group I lines in 1980, and was less than 1% on the single Group II line. In 1981 open pollination seed set was lower, ranging from 1 to 18%, but evidence of crossing was confirmed by the use of pollinators with a marker gene.
Production and Performance of Hybrid Soybeans1
Authors: Nelson Randall L. , Bernard Richard L.
Published: July 2010

The quest for hybrid cultivars in self‐pollinated crops has been encouraged by the great success achieved in hybrid corn (Zea mays L.). However, because past research has relied on hand pollinations to produce hybrid seeds in soybeans [Glycine max (L.) Merr.] very little is known about the performance of hybrid soybeans. The objectives of this study were to look for heterosis in seed yield of soybean hybrids and to compare other characteristics in the hybrids with those of the parents. All hybrid seeds in this study were produced using genetic male sterility and insect pollination. The experiments were grown at Urbana, III. in a Flanagan silt loam (Aquicarguidoll) and Belleville, 111. in an Ebert silt loam (Argiaquicargialdoll), in 1977 and 1978. Agronomic data were collected from 27 hybrid combinations grown in replicated, bordered plots. Five hybrids yielded significantly more (13 to 19%) than their better parent in at least one season. Only one hybrid exceeded the yield of the best pure‐line cultivar in the test. The yield performance of the hybrids could not be predicted from their pedigrees. Several hybrids significantly exceeded the height of the taller parent, but, with few exceptions, no high‐parent heterosis was observed for maturity date, lodging score, harvest index, seed quality, seed weight, oil percentage, or protein percentage. Significant heterosis was observed even though relatively few hybrids were tested and the parents were unselected for combining ability. The inability to produce large quantities of hybrid seeds economically is the major barrier to the use of commercial hybrid soybean cultivars.
Phenotypic Recurrent Selection for Stem Length in ‘Kenstar’ Red Clover1
Authors: Bowley S. R. , Taylor N. L. , Cornelius P. L.
Published: July 2010

The effect of six cycles of phenotypic recurrent selection for stem length in red clover (Trifolium pratense L.) was studied in spaced plantings and in drilled plots. The objectives were to evaluate the genetic and agronomic changes that occurred during selection and to determine if further increases in stem length are possible. To determine if inbreeding occurred during selection of these populations, F1 crosses between the selected populations and clones from the base population also were tested in spaced plantings. Over cycles of selection, stem length increased linearly 3.7 and 2.9 cm/cycle at first and second harvests, respectively, as evaluated in spaced plantings. Internode counts and histological examinations indicated that the lengthened stems were due to more cells per internode. No appreciable changes were detected in internode numbers or maturity. Estimates of the weighted average change in allelic frequency indicated inbreeding depression was not an important factor in the advanced cycles. A linear increase in stem length, lack of inbreeding depression, and maintenance of phenotypic variance over cycles of selection indicated that further increases in stem length would be possible if selection were continued. Selection for increased stem length was accompanied by decreases in stem number per plant and persistence. Herbage yield in spaced plantings increased over cycles at first harvest but declined over cycles in the regrowth. Redistribution of photosynthates from normal root and crown development or changes in root reserves were suggested as reasons for the initial yield increase and subsequent decline. Selection among plants after regrowth or in the 2nd year were proposed as methods of avoiding similar undesirable changes in breeding red clover.
Confirmation by Mitochondrial DNA Analysis of a Euplasmic Spring Wheat Expressing a Dominant Male‐Sterility Gene1
Authors: Altman D. W. , Storey K. K. , Gengenbach B. G.
Published: July 2010

A dominant male‐sterility gene has had limited utilization in wheat (Triticum aestivum L.) breeding partly because appropriate lines have alien (T. tauschii Schmal.) cytoplasm. The dominant allele for male‐sterility was though to have been transferred into a euplasmic (T. aestivum cytoplasm) background, but the cytoplasmic constitution of this line had not been confirmed. Electrophoretic gel patterns of mitochondrial DNA (mtDNA) a putative euplasmic line which segregates for the dominant male‐sterility allele were compared with gel patterns of mtDNA of known T. aestivum and T. tauschii cytoplasm lines following digestion with the restriction endonucleases PstI, EcoRl, BamHI, Sall, Xhol, and Hindlll. All restriction patterns of the putative euplasmic line verified that the cytoplasm was from T. aestivum. Euplasmic sources of dominant male‐sterility should have greater value than alloplasmic lines for future genetic and breeding studies using this gene.
Inheritance of Ineffective Nodulation in Crimson Clover1
Authors: Smith G. R. , Knight W. E.
Published: July 2010

A single plant of crimson clover (Trifolium incarnation L.) appearing to have ineffective nodules was identified under nil‐N conditions from a 1000‐pIant population of the cultivar Chief. The plant (designated CH‐I) had tiny, white, beaded nodules and only 2 cm of topgrowth. With the addition of N this plant was grown to maturity and self‐pollinated. S1 plants were inoculated with 11 different Rhizobium trifolii strains in replicated experiments, all resulting in an ineffective symbiosis. No segregation for effectiveness occurred in the S1 or S2 generations of the CH‐I line. Crosses were made between normal crimson clover lines and S1 lines of CH‐I. F1 populations were nodulated effectively with R. trifolii strain 162K13. The Fz generation segregated for symbiotic effectiveness when nodulated with strain 162K13. F2 populations from two crosses showed a good fit to a 3:1 ratio of normal to ineffective nodulation. Results indicate that non‐strain‐specific ineffective nodulation of crimson clover is controlled by a single recessive gene pair (rt1 rt2) with possible modifiers. Plants with this trait should be useful as non‐Nj fixing controls in 15N isotope dilution experiments and to study individual steps in N2 fixation.
Direct Measurement of Irradiance upon Phototropic Soybean Leaves throughout the Day
Authors: Woolley Joseph T. , Alfich Robert A. , Larson Eric A.
Published: July 2010

Small solar cells attached to soybean [Glycine max. (L.) Merr. ‘Corsoy’] leaflets were used to measure the irradiance upon the leaflets throughout the day. Irradiance upon five fixed plane surfaces was also measured and compared with the leaf irradiance. Under some conditions the upper leaves received more radiant energy than did any fixed plane. Phototropism increased the total radiant energy interception by leaves at the top of the crop canopy. The midday inward movement of leaflets reduced the energy interception by the top leaves and allowed more light to reach the lower leaves.
Yield, Fiber and Spinning Performance of Interspecific Cotton Hybrids Having a Common Parent1
Authors: Weaver J. B. , El‐Marakby A. M. , Esmail A. M.
Published: July 2010

‘Pima S‐5’ (Gossyplum barbadense L.) was crossed as a common male parent onto 13 upland cotton (G. hirsutum L.) genotypes. The F1's, along with ‘Coker 310’ and Pima S‐5 as checks, were grown in 1976 and 1977 to evaluate their yield, fiber, and spinning performance. The lint yield mean over 1976 and 1977 for the hybrids as a group was significantly higher than that of Pima S‐5. In 1977, 10 hybrids produced essentially the same yield as Coker 310; three produced less. Boll size for all hybrids was intermediate between that of Coker 310 and Pima S‐5 while lint percentage was lower than both. Fiber lengths (2.5 and 50% span lengths) of the hybrids were the same as or longer than Pima S‐5. All hybrids had stronger fiber than Coker 310, and some produced fiber as strong as Pima S‐5. Fiber elongation and uniformity index differences were not detected. Spinning tests of yarn and thread from lint of the hybrid ms5ms6 ✕ Pima S‐5 showed a slight advantage for percent elongation, percent uniformity, and number of thin places/1000 m as compared to Pima. However, this hybrid was slightly lower in yarn and thread tenacity. Number of thick places and nep count/1000 m were higher in the yarn from the hybrid, but they were lower in the thread from the hybrid as compared to Pima. Thread color and appearance, following a dyeing test, were similar in both types of cotton. The higher number of neps in the yarn from the hybrid might be partially attributed to saw ginning of its seed cotton and to the low fiber maturity characteristic of this hybrid. Nine hybrids possessed fibers with narrow diameters coupled with fiber maturity comparable to Pima and would be expected to give similar spinning performance for neppiness.
Presence of Dhurrin in Sorghum Root Tissue and the Effect of Pathogenesis on Hydrogen Cyanide Potential1
Authors: Starr J. L. , Newton R. J. , Miller F. R.
Published: July 2010

The presence of dhurrin and cyanogenic activity in roots of sorghum was tested utilizing gas liquid chromatography and color reagents. Of 15 Sorghum bicolor (L.) Moench accessions tested, all gave a positive response for cyanogenic activity in the seminal root system based on a qualitative assay. Dhurrin concentrations of 18 to 25 g/kg were detected in freeze‐dried, primary roots of NK262 and ATx399 ✕ RTx430. The lateral roots of ATx399 ✕ RTx430 contained less dhurrin (3 to 5 g/kg dry weight) than did the primary root (25 g/kg dry weight) of the seminal root system. Pathogenesis of the primary root by the lesion nematode Pratylenchus zeae Graham or the root‐rot fungus Pythium arrhenomanes Dresch. decreased the hydrogen cyanide potential of lesion tissue by ca. 50% 48 h after inoculation relative to healthy roots. Dhurrin concentrations in lateral roots of the seminal root system were too low to measure the effect of pathogenesis on hydrogen cyanide potential. The possible significance of the effect of pathogenesis on hydrogen cyanide potential of root tissues is discussed.
Prospects for Genetic Improvement in the Quackgrass ✕ Bluebunch Wheatgrass Hybrid1
Authors: Asay K. H. , Hansen W. T.
Published: July 2010

A promising F7 breeding population has been derived from the quackgrass [Elytrigia repens (L.) Nevski] ✕ bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Löve] hybrid after 20 years of selection. Field studies were conducted to determine the potential of making additional genetic advances in subsequent generations. Significant differences were found among 172 hybrid clonal lines and their open pollinated progenies for seed and forage yield and extent of rhizome development. Broad‐sense heritabilities were 94, 40, and 87% for seed and forage yield and rhizome development, respectively. Phenotypicorrelations (r, 170 df) among parental and progeny means were 0.30 for seed yield and ranged from 0.38 to 0.50 for rhizome development. Positive responses to selection pressure to alter the degree of rhizome development in the hybrid population add credence to the relatively high heritability estimates obtained. True‐breeding caespitose or rhizomatous strains have been developed after two cycles of selection. A hybridization program to broaden the genetic base of the breeding population has been initiated.
Screening Methodology for Resistance to Field Weathering of Soybean Seed1
Authors: Dassou S. , Kueneman E. A.
Published: July 2010

Soybean [Glycine max (L.) Merr.] seeds may lose vigor prior to harvest, especially when grown in humid, tropical environments. This study compared three seed weathering treatments to identify soybean genotypes with resistance to field weathering of seed. Thirty‐five genotypes were planted in replicated trials on three dates and subjected to 1) field weathering (seeds were harvested 3 weeks after physiological maturity), 2) incubator weathering (pods at physiological maturity were detached from the plant and kept at 30°C and 90 to 95% relative humidity for 10 days), and 3) wet‐bag weathering (plants at physiological maturity were placed in wet burlap bags for 10 days). Under the wet‐bag treatment, extreme seed deterioration of nearly all genotypes tended to mask their differences in resistance. Incubator weathering was more consistent across experiments than field weathering. Mean seedling emergence scores varied less among experiments for incubator weathering (30, 28, and 22%) than for field weathering (78, 46, and 54%). The genotype ✕ planting date interaction accounted for 7 and 29% of the total sums of squares for incubator and field‐weathering, respectively, indicating that incubator weathering minimized environmental effects that would confound comparisons among genotypes of different maturity. The percentage of hard seed after 1 h of soaking ranged from 0 to 64% and was correlated (r = 0.73, P < 0.01) with seedling emergence following incubator weathering. Large‐seeded genotypes were generally susceptible to seed weathering and deterioration in storage. Some small‐seeded genotypes were resistant; others were susceptible. Black‐seeded genotypes were more resistant to incubator weathering than yellow‐seeded genotypes. Genotypes with a high percentage of seedling emergence following incubator weathering also had high seedling emergence after ambient storage. Genotypes identified as having resistance to weathering of seed and to deterioration in storage were: INDO 153, INDO 131, INDO 243, INDO 226, INDO 255, ‘Fort Lamy’, ‘Lee A’, INDO 173A, and ‘Biloxi 3’.