bluuebunny/crossref_metadata_2025 huggingface dataset:
Spontaneous and Induced Interspecific Gene Transfer For Crown Rust Resistance in Avena1
Authors: Sharma D. C. , Forsberg R. A.
Published: July 2010

Crown rust resistance from Avena tetraploid CI 7232 was transferred to Avena sativa L. utilizing irradiation with thermal neutrons. The relationship between an alien chromosome from CI 7232 and its homologue in hexaploids was also studied.

CI 7232, derived from a cross between A. abyssinica Hochst. (2n=28) and A. strigosa Schreb. (2n=14), possesses resistance (Pc‐15) to crown rust (Puccinia coronata Cda. f. sp. avenae Fraser and Led.) from A. strigosa. Earlier, CI 7232 was crossed with the susceptible hexaploid ‘Clarion’, and dark kernel color (D) and resistance (R) from the tetraploid parent were linked in nearly all F8 F10 lines. Only one of 1,355 F7 plants was found to have light kernel color (L) and resistance. We previously reported that all D‐R and L‐R plants were unstable for rust resistance, and that this instability was caused by the failure of a substituted alien chromosome (1′A) to transmitted through the pollen.

In this study, seeds from two L‐R plants with 20″ 1′+1′A were irradiated with thermal neutrons (Total dose: Flux ✕ time of 8.8 ✕ 1012 / Nth / cm2). Irradiated seeds were space planted in a field nursery, inoculated with crown rust in early tillering stages, and classified prior to heading. Resistant plants were then crossed as pollen parents to Clarion as a screen for functional male gametes carrying resistance. Two of the resulting I‐Fl's were resistant, and ratios in their respective I‐F2 and I‐F3 populations confirmed monofactorial inheritance. Thus, Pc‐15 had been transferred from the alien chromosome to one in the hexaploid complement which had normal male and female transmission. Metaphase I and tetrad observations in two homozygous and two heterozygous I‐F3 plants revealed completely normal meiosis.

In the original, nonirradiated, monosomic alien substitution plants (20″+l′+l′A), L‐R or D‐R alien chromosomes were loosely associated with their hexaploid mate in about 85% of the cells, but recombination between the two marker loci occurred only rarely. The L‐R recombinant chromosomes evidently still carry a large, non. homologous segment of the alien chromosome (including Pc‐15) which completely blocks its pollen transmission.
Leaf Orientation and Yield of Maize1
Authors: Pepper G. E. , Pearce R. B. , Mock J. J.
Published: July 2010

The advantage of vertically oriented leaves in crop canopies has been studied with variable results. In many maize (Zea mays L.) populations there is a wide variation of leaf orientations. Nine maize inbreds visually selected for upright, intermediate, and horizontal leaf orientation were grown in 51‐cm rows at three plant densities at Iowa State University. Each inbred was evaluated for 2 years for leaf area index, light extinction coefficient (k), dry‐matter yield, and grain yield, and 1 year for leaf orientation and leaf display. We developed a new leaf orientation parameter, leaf orientation value (LOV), to account for the ability of leaves to maintain the same orientation for their entire length. This parameter was easier to measure than k, is a good indicator of leaf orientation, and could be used as a selection index for leaf orientation. Differences in dry matter yields and grain yields across leaf orientation groups agreed with expectations based on theories involving leaf orientation and leaf area index; i.e., yield advantages for genotypes with upright leaves were observed only at high leaf area indices.
Genetic Improvement in Yield of Soybeans1
Authors: Luedders Virgil D.
Published: July 2010

Average soybean (Glycine max (L.) Merr.) yields have increased considerably due to changes in cultivars and cultural practices. To evaluate the genetic improvement, yields, lodging, and plant height of 21 cultivars were determined in 3 years. Most of these cultivars were involved in essentially two cycles of recurrent selection. Yield increases were 26 and 16% for the first and second cycles of selection, respectively, while lodging decreased 21 and 20%. Plant height increased slightly.
Heterosis in Full‐sibs Within and Between Half‐sib Families in Open‐Pollinated Varieties of Maize1
Authors: de León Jóse Luis , Lonnquist J. H.
Published: July 2010

When the full‐sib reciprocal recurrent selection RRS(F) scheme is applied in a single open‐poliinated maize (Zea mays L.) population each random fuli‐sib (FS) family the result of a cross of plants from (a) within previous half‐sib (HS) family or (b) plants from different previous HS families. The effects of resulting differences in inbreeding on the heterosis in the two kinds of families were studied. Samples of each type were developed and evaluated in each of two maize populations. Grain yield, ear height, and moisture at harvest were considered. Results showed that FS between HS outyielded FS within HS families by 8.5 and 11.7% in the ‘Northwestern Dent’ variety and in ‘Early Flint’ composite, respectively. Assuming a 1% loss in yield for each 1% increase in inbreeding, both figures approach the 12.5% inbreeding coefficient calculated for FS within HS families.

Full‐sibs made at random in a maize population are most likely to be FS between plants from different HS families. Some will not be. In the initiation of RRS(F) within a population, advantages exist where HS families are identified so as to assure that all FS arise from parents of different HS. Lower yielding FS formed from within HS family crosses will be avoided and not included in performance trials. This would enhance selection of superior FS crosses and increase genetic progress when a RRS(F) program is applied in maize breeding.
Interference of Gossypol in Bioassay for Resistance to Tobacco Budworm in Cotton1
Authors: Shaver T. N. , Dilday R. H. , Garcia J. A.
Published: July 2010

The effect of gossypol on suppressing larval growth of tobacco budworms, Heliothis virescens (F.), was enhanced by diethyl ether extracts of flowerbuds of cotton (Gossypium hirsutum L.). This effect was greater with extracts of glanded than with glandless flowerbuds. The greater increase in larval growth suppression caused by these extracts is sufficient to interfere with the laboratory bioassay for detecting sources of antibiosis other than gossypol in cotton fiowerbuds. Also, results of these laboratory tests suggest that a significant and useful larval growth suppression can be obtained with less than 1.2% gossypol in the flowerbud.
Root Storage Respiration Rate in a Diallel Cross of Sugarbeet1
Authors: Theurer J. C. , Wyse R. E. , Doney D. L.
Published: July 2010

A 2‐year study of root respiration rate was conducted for eight sugarbeet (Beta vulgaris L.) inbreds and their 28 diallel crosses in 1974 and nine inbreds and their 36 diallel crosses in 1975. Objectives were to determine the potential of selection and breeding to reduce sugar losses in storage. Hybrids usually showed a lower respiration rate than either inbred parent. Heterosis for low respiration rate was observed both years. General and specific combining ability was significant, indicating that respiration rate is governed in part by both additive and non‐additive gene acton. Thus, selection to reduce storage sugar losses due to respiration can be effective in sugarbeets. Selection for low respiration rate will not adversely affect root yield or sugar content.
Genetic Variability in Acid Detergent Fiber, Crude Protein, and Their Association with Some Morphological Characters in Smooth Bromegrass1
Authors: Tan Wai‐Koon , Tan Geok‐Yong , Walton P. D.
Published: July 2010

A seven × seven half diallel of smooth bromegrass Bromus inermis Leyss., including parental clones, was evaluated for acid detergent fiber (ADF) and crude protein (CP) of whole forage at two harvests and of leafblade, leaf‐sheath, and stem sampled before the first harvest. The objectives were to assess the genetic variability for the quality components, and to examine the associations between the two quality components and some morphological characters.

The relative magnitude of the variances due to general and specific combining ability indicated that most of the genetic variance appeared to be nonadditive. Neither ADF nor CP showed significant combining ability at the second harvest. The narrow‐sense heritability estimates were quite high for ADF of the leaf‐blade (46%) but were very low for ADF and CP of whole forages at both harvests (3 to 8%) and for ADF of other plant fractions (0 to 19%). The nature of the genetic variances for ADF and CP suggested that more complicated breeding methods would be necessary for quality improvement.

Acid detergent fiber of the leaf‐sheath and stem was closely associated with whole forage ADF (r = 0.70 and 0.84). High correlations were obtained between harvests for both ADF and CP (r = 0.71 and 0.61). ADF increased while CP decreased with increasing plant height and forage yield. Vein frequency was positively correlated with ADF of whole forage (r = 0.41) and leaf‐sheath (r = 0.51). Most phenotypic characters showed little correlation with either ADF or CP at the first harvest.
Effects of Temperature and Irradiance on Seedling Growth of Smooth Bromegrass1
Authors: Tan Geok‐Yong , Tan Wai‐Koon , Walton P. D.
Published: July 2010

Smooth bromegrass (Bromus inermis Leyss.) seedlings grown in four environments were used to study effects of temperature and irradiance on seedling growth. Differences between environments, between stages of growth, and their interaction were significant for tiller number, leaf number, leaf area, specific leaf weight, shoot‐to‐root ratio, dry weight of leaf, shoot and root, and seedling dry weight. Both main effects and their interaction were highly significant for relative growth rate (RGR) and leaf area ratio (LAR), while for net assimilation rate (NAR) differences between environments were non‐significant. Seedlings grown in high light and high temperature environments produced higher dry matter than those grown in low light or low temperature. The effect of irradiance was greater than that of temperature for most characters studied. Both RGR and NAR declined gradually with advancing plant age in all environments; LAR declined only in high light environments. Simple correlation coefficients revealed that increasing RGR and LAR could be accompanied by increasing tiller number, leaf number, leaf area, seedling dry weight and shoot‐to‐root ratio. Highly significant correlations were obtained between RGR and LAR (0.69 to 0.93 at 0.001 level), whereas there was no correlation between RGR and NAR. It is apparent that variation among environments in dry matter production of bromegrass seedlings was attributed to differences in LAR rather than NAR. Specific leaf weight was negatively correlated with RGR at the 0.001 level (−0.90) and LAR (−0.97), but positively correlated with NAR at the 0.05 level (0.47).
Callus Induction and Plantlet Regeneration in Orchardgrass1
Authors: Conger B. V. , Carabia J. V.
Published: July 2010

Callus was initiated from whole caryopses of orchardgrass (Dactylis glomerata L. ‘Boone’) on a modified Schenk‐Hildebrandt (SH) medium containing 15 mg/liter of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2.15 mg/liter of kinetin. Calli were transferred twice at 3‐week intervals and maintained on a modified medium containing 5 mg/liter of 2,4‐D. Organogenesis was observed on the third subculture when the 2,4‐D concentration was reduced to 1 mg/liter. Callus was produced from nearly every caryopsis and roots or root hairs could be induced on most calli. Shoot regeneration was, however, less frequent. In one experiment, 11 of 119 calli generated shoots on the third subculture. Weak root growth on calli with shoots could be stimulated by transfer to an SH medium without hormones and in which the inorganic constituents had been diluted by one‐half. After sufficient root and shoot growth, seedlings could easily be transferred to pots, and actively growing plants established.
Phenotype, Fiber Composition, and in vitro Dry Matter Disappearance of Chemically Induced Brown Midrib (bmr) Mutants of Sorghum1
Authors: Porter K. S. , Axtell J. D. , Lechtenberg V. L. , Colenbrander V. F.
Published: July 2010

Chemically induced brown midrib (bmr) mutants sorghum (Sorghum bicolor (L.) Moench) were characterized with regard to phenotype, fiber composition, and in vitro dry matter disappearance (IVDMD). The recessive bmr genes produced brown pigmentation in the leaf midrib and stem of mature plants. Pigmentation varied among mutants in intensity, time of appearance, and degree of fading as plants matured.

Stem and leaf samples of mutant and normal plants were analyzed in the laboratory to determine percent cell wall constituents (CWC), acid detergent fiber, (ADF), cellulose, hemicellulose, permanganate lignin (PL), vitro dry matter, and in vitro cell wall constituent disappearance (IVDMD and IVCWCD). Ten of the 13 mutants had significantly less stem lignin than the normal counterparts. Reductions in lignin ranged from 5 to 51% in stems and from 5 to 25% in leaves. In the case of other fiber components, only occasional differences were observed between normal and mutant plants. Increases in IVDMD and IVCWCD of as much as 33 and 43%, respectively, were associated with the presence of bmr genes.

Variation among mutants in lignin concentration probably indicates that several different bmr genes were involved. Similarities between the bmr genes of sorghum and the bm genes of maize (Zea mays L.) suggest the possible existence of similar genes in other grasses, although their identification may be more complicated because of polyploidy.
Photosynthetic Rate and Diffusion Conductance as a Function of Age in Leaves of Bean Plants1
Authors: Davis S. D. , McCree K. J.
Published: July 2010

Bush beans (Phaseolus vulgaris L.) were grown and tested under constant environmental conditions. Simultaneous measurements of CO2 exchange rates and H2O diffusion conductances were made on individual leaves, throughout all stages of leaf and plant development. Both exchange rate and leaf conductance (reciprocal of resistance) declined with leaf age. In both cases the data for all leaves fell on a single straight line, when plotted against time expressed as a percentage of the time from maturity to death. The decline in conductance was not sufficient to explain the decline in the exchange rate. There was a proportionate decline in the internal photosynthetic capacities of the leaves. Since the CO2 concentration in the substomatal cavity was found to remain almost constant, and the external conditions (light, temperature, water status) were kept constant, the decline in conductance was either due to a real decrease in the abilities of the stomates to stay open or a compensating adjustment of stomates by a CO2 feedback process.
Cross Pollination Studies of Male‐Sterile Genotypes in Cowpeas1
Authors: Rawal Kanti M. , Bryant Peter , Rachie K. O. , Porter W. M.
Published: July 2010

The purpose of this investigation was to determine if flower color preference of honey bees (Apis meilifera L.) influenced the cross pollination of male sterile (ms2ms2) cowpeas (Vigna unguiculata (L.) Walp.). Since growth habits of cowpeas, ranging from acute erect and determinate to prostrate or climbing and indeterminate, result in different numbers of flowers produced per plant, growth habits were taken into consideration when computing bee preference for different flower colors. Plants with prostrate indeterminate growth habit and completely pigmented flowers produced significantly more pods than any other combination. For recurrent selection programs using male‐sterile cowpeas, natural cross‐pollination by bees may lead to marked shifts in gene frequencies for dark seed coat colors because flower pigmentation and seed colors are pleiotropically associated.
Effects of Temperature and Competition on the Establishment and Growth of Redroot Pigweed and Common Lambsquarters1
Authors: Chu Chang‐chi , Ludford Pamela M. , Ozbun Jim L. , Sweet Robert D.
Published: July 2010

A comparison was made of the germination, growth, and leaf CO2‐exchange rates of redroot pigweed (Amranthus retroflexus L.) and common lambsquarters (Chenopodium album L.) under varied temperature regimes. It was found that redroot pigweed had greater rates of germination, growth, and CO2‐exchange rates at high temperatures, whereas common lambsquarters performed better at low temperatures. The implications of such characteristics for competition between these species of weeds and their effect on crops are discussed.
Polymorphism for Vernalization Requirement in a Winter Oat Cultivar1
Authors: Qualset C. O. , Peterson M. L.
Published: July 2010

‘Blount’ oats (Avena sativa L.) is a winter cultivar that showed about 35% spring‐type plants when spring‐planted in Tennessee. The spring‐type plants were as winter‐hardy as the winter‐type plants and nonresponsive to vernalization. Blount was variable for heading time after fall planting, but the variation was not related to the vernalization response. The polymorphism for vernalization requirement apparently had no adverse or beneficial effects on the population when fall‐planted, except for possible benefits in population stability over seasons. However, with spring planting the original cultivar was more productive than the homogeneous winter‐type populations, but much less productive than the spring‐type population. Winter‐hardy cultivars not requiring vernalization may be useful in areas where high levels of winter‐hardiness are not needed and where both spring and fall planting may be desirable.
Second‐brood Damage by Southwestern Corn Borer in a Corn Diallel Cross1
Authors: Scott Gene E. , Davis Frank M.
Published: July 2010

Plants from reciprocal diallel crosses among nine (seven resistant and two susceptible) genotypes of corn (Zea mays L.) were evaluated for damage by second‐brood southwestern corn borer (Diatraea grandlosella Dyar). All plants were infested with southwestern corn borer eggs at silking time, and the extent of damage to the plant was determined 35 days later.

Mean squares for maternal, reciprocal, and specific combining ability were small and generally not significant. Selections from populations 44# and 45# contributed a higher level of resistance to their crosses than did the other three resistant parents. The resistant ✕ resistant crosses had 36% fewer tunneled plants than the susceptible ✕ susceptible cross, and these tunneled plants had only 56% as much damage.
Competition between Two Soybean Isolines in Hill Plots1
Authors: Wilcox J. R. , Schapaugh W. T.
Published: July 2010

Intergenotypic competition was assessed between two soybean (Glycine max (L.) Merr.) isolines, ‘Clark’ and Clark‐e2, the latter maturing 14 days earlier than Clark, in hill plots at 15 spacings ranging from 0.093 to 2323 m2/hill. When Clark was bordered with Clark‐e2 on two or four sides at spacings of 0.121 through 1.162 m2/hill, its yield was significantly greater than when it was selfbordered at the same spacings. Conversely, when Clark‐e2 was bordered by Clark at spacings of 0.093 through 1.162 m2/hill, yields were significantly depressed below those of self‐bordered Clark‐e2
Evaluation of Potassium 3,4‐Dichloroisothiazole‐5‐Carboxylate as a Harvest‐Aid Chemical on Cotton1
Authors: Cathey George W.
Published: July 2010

Chemical defoliants usually cause varying amounts of leaf abscission when applied to cotton (Gossypium hirsutum L.). This variation is due mainly to environmental factors, but may also be influenced by plant characteristics. The objective of this research was to evaluate the effect of potassium 3,4‐dichloroisothiazole‐5‐carboxylate (TD‐1123) in altering leaf abscission response of cotton to conventional defoliant chemicals. Field and greenhouse studies employed rates of TD‐1123 that varied from 0 to 1.12 kg/ha, and timing of application that ranged from 0 to 4 weeks before defoliant chemical treatments. Measurements were made to determine effects of rate and time of application of this chemical on leaf abscission, regrowth development, yield of seed cotton, and various boll and seed properties.

TD‐1123 failed to alter leaf abscission response of greenhouse plants when applied as a mixture with DEF (S,S,S‐tributylphosphorotrithioate), but caused a significant increase in abscission rate and total defoliation when applied 1, 2, or 4 weeks prior to DEF. The 1 and 2‐week pretreatments, however, were the most effective in this respect. Regrowth development was also reduced in the 1 and 2‐week pretreatments of greenhouse plots, but was increased when applied 4 weeks before DEF. The rates of TD‐1123 that gave the greatest abscission response were 0.28 and 0.56 kg/ha. Seed germination, however, was reduced when these rates were applied 4 weeks prior to DEF.

Regrowth, yield, and boll components of field cotton were not affected by TD‐1123 at rates of 0.28, 0.56, or 1.12 kg/ha. These rates, however, were equally effective in increasing leaf abscission response to DEF. A 10‐day pretreatment of 0.336 kg TD‐1123/ha also increased leaf abscission with sodium chlorate and with DEF + endothall [7‐oxabicyclo(2.2.1)heptane‐2,3‐dicarboxylic acid] mixtures. This research indicates that TD‐1123 can be an effective harvest‐aid chemical on cotton.
Inheritance of Stem Rust Resistance in ‘Webster’ Wheat1
Authors: Knott D. R. , McIntosh R. A.
Published: July 2010

Inheritance of seedling resistance to stem rust (Puccinia graminis f. sp. tritici Eriks. & E. Henri.) in ‘Webster’ wheat (Triticum aestivum L.) was studied in testcrosses and in crosses with the ‘Chinese Spring’ monosomics. Studies in Canada and Australia showed that its resistance to several North American and Australian races of stem rust is controlled by the same nearly recessive gene, which is designated Sr30. Analysis of the monosomic crosses indicated that Sr30 is on chromosome 5D.

The cultivar ‘Festiguay’, which also carries Sr30, was crossed with a Chinese Spring 5DL ditelocentric line, a 5DL ditelocentric line in which the telesomes carried Lrl, and a euploid marker stock homozygous for Lrl and Pm2. The results of these crosses indicated that Sr30 is on the long arm of chromosome 5D and is probably independent of the centromere, Lrl and Pm2. Pm is presumed to be on the short arm, with the order being Pm2 — the centromere — Lrl — Sr30.
Effects of Two Yield Component Selection Procedures on Maize1
Authors: Geadelmann J. L. , Peterson R. H.
Published: July 2010

Breeders of maize (Zea mays L.) have been concerned with relationships between yield and yield components and the effects of plant density on these relationships. We used three inbred lines (A251, A556, and A619) and backcross‐selection procedures for kernel depth, ear length, and ears per plant to develop six modified versions of each inbred: deep kernel (D), long ear (L), multiple ear (M), deep kernel and long ear (DL), deep kernel and multiple ear (DM), and long ear and multiple ear (LM). A normal (N) inbred plus its six modified versions were crossed with their counterparts in each of the two other inbred backgrounds to produce seven types of single‐cross hybrids: N, D, L, M, DL, DM, and LM. The 21 hybrids were evaluated at plant densities of 24,700, 49,400, and 74,100 plants/ha in 2 years at two locations per year. The objectives of this study were to compare the effects of backcross‐selection for one vs. two of the yield components and to estimate the relative effects of such backcross‐selection on response of hybrids to plant density.

Expression of the selected yield component in single component types of hybrids usually exceeded that of their normal counterparts. Increase in expression of selected yield components in double component types occurred only for ears per plant at low plant density and ear length at higher plant densities. Yields of D, L, M, DL, DM, and LM hybrids were −4.2, +3.6, +6.6, −8.0, +0.4, and −2.2%, respectively, of yields of N hybrids when averaged over plant densities and genetic backgrounds. Modified hybrids, particularly double‐component types, did not respond well to medium and high densities. Within the highest yielding hybrid background (A619 ✕ A251), no modified hybrid significantly exceeded the yield of the normal hybrid at any density. Within the limits of our evaluation, backcross‐selection for yield components does not seem to be a useful procedure for improving high yielding hybrids grown at plant densities common in much of the Corn Belt. It might be a useful breeding procedure to improve yield in specific circumstances, e.g., in relatively low yielding hybrid backgrounds, especially at lower plant densities.
Floral Initiation and Development in Cultivars of Oats1
Authors: Cisar G. , Shands H. L.
Published: July 2010

Five cultivars of spring oats (Avena sativa L.), ranging in maturity from early to late, were planted on several dates in 1972 and 1973. Plant samples were collected from each cultivar starting at the four‐leaf stage and continuing at 3‐day intervals until anthesis was observed in apical florets. These samples were dissected to expose the reproductive axis in order to follow its seasonal development and to differentiate floral development patterns that influence panicle expansion in different cultivars to determine the effect of planting date on floral development and to compare floral development in the first and second tillers of the plant.

Cultivar maturation was influenced by the length of time of the vegetative stage, the length of the reproductive phase as affected by rate and amount of primordia addition, and rate and amount of panicle elongation.

Later planting dates hastened sexual maturity of all cultivars by shortening the vegetative stage, hastening primordium addition, and decreasing total panicle length. Panicle development in the second tiller paralleled that of the first tiller, hut was delayed 2 to 4 days.
Seed Damage by Pink Bollworm to Race Stocks, Cultivars, and Hybrids of Cotton1
Authors: Wilson F. D. , Wilson R. L.
Published: July 2010

Noncultivated race stocks of cotton (Gossypium hirsutum L.) previously selected via diet bioassays for antibiosis to pink bollworm (Pectinophora gossypiella Saunders), were field‐tested for resistance along with cultivars and race stock ✕ cultivar F1 hybrids. No race stock or hybrid was consistently more resistant than the cultivars in 1975. In 1976, one race stock, Texas 40, and two hybrids showed some resistance. The general lack of resistance in the field among race stocks previously selected for antibiosis in diets was disturbing but not necessarily unexpected because the two types of tests might have measured different facets of resistance. Results showed the need for a more direct measure of antibiosis in diet‐selected stocks, such as placing larvae on bolls of live plants. Genetic differences in hybrids were attributed to differences among their race‐stock parents. Race stock ✕ harvest‐date interactions in both years, and cultivar ✕ harvest‐date interactions in 1975 were caused by hybrid combinations in which seed damage by pink bollworm increased at different rates. Gene action was presumably primarily additive because cultivar ✕ racestock interactions were nonsignificant and because most hybrid/harvest‐date combinations did not differ from the midparent (MP). One hybrid array deviated consistently from MP in the direction of increased seed damage and one deviated in the opposite direction. Correlations between seed damage and six agronomic characters showed no consistent pattern.
Cold Hardiness Potential of Triticale and Teraploid Rye1
Authors: Dvorak J. , Fowler D. B.
Published: July 2010

Cold hardiness is the primary factor restricting the area of winter wheat (Triticum aestivum L. em Thell.) production in North America. Related species are potential sources of genetic variability that could be used in the improvement of winter wheat cold hardiness. Among these relatives, rye (Secale cereale L.) has shown the greatest ability to tolerate cold. However, exploitation of this source would be feasible only if the genes for cold hardiness in rye were expressed when in association with the wheat genomes. To determine the level of this expression seven octaploid triticales were produced. These triticales and their parental winter wheat and rye cultivars were then assessed for cold hardiness in artificial freeze tests. In all instances the triticales achieved only the cold hardiness of their parental wheat cultivars. The effect of increasing ploidy level on the expression of cold hardiness in rye was also investigated. The cold hardiness of seven autotetraploid rye populations was compared with the cold hardiness of their parental diploid populations. All autotetraploid populations were not as cold hardy as the corresponding diploid populations, indicating that polyploidy has an adverse effect on the expression of genetic systems controlling cold hardiness in rye. Based on these observations, it appears that rye is an unsuitable source of genes for the improvement of cold hardiness in polyploids such as common wheat.
Influence of Harvest Date and Freezing on Sunflower Seed Germination1
Authors: Zimmerman D. C. , Zimmer D. E.
Published: July 2010

Sunflowers (Helianthus annuus L.) grown in North Dakota and Minnesota are frequently exposed to freezing temperatures before the plants mature, and the seed they produce will often fail to germinate. This study was conducted to determine the influence of artificial freeze treatments at progressive maturity stages. Sunflower heads (capitula) were harvested at weekly intervals from 28 to 68 days after flowering (DAF) 1973 and 1974. Germination percentages, measured 7 days after harvest (DAH), increased from 6 to 84% in 1973 and from 0 to 48% in 1974 with increased time between flowering and harvest. Freezing prior to 42 DAF blocked or altered some physiological process necessary for germination and resulted in seeds with lower germination. Seed harvested later in the growing season had a shorter dormant period than that harvested earlier. Growing degree days from flowering to harvest were significantly correlated with percent germination at 21 DAH in 1973 (r = 0.95, significant at 0.01 level) and 35 DAH in 1974 (r = 0.99, significant at 0.01 level).
Esterase Isoenzyme Differences in Seed Extracts among Soybean Cultivars1
Authors: Payne R. C. , Koszykowski T. J.
Published: July 2010

Seed extracts of 44 soybean [Glycine max (L.) Merr.] cultivars were analyzed by polyacrylamide disc electrophoresis for esterase activity. Five esterase isoenzymes were consistently detected in all of the cultivars. There were quantitative differences among cultivars in the activity of the two isoesterases having higher Rf values. These differences should serve as aids in identifying soybean cultivars.
Nitrate Reductase as a Factor Affecting N Assimilation During the Grain Filling Period in Spring Wheat1
Authors: Simmons Steve R. , Moss Dale N.
Published: July 2010

In 1976 we investigated whether or not nitrate reductase (NR) enzyme activity in shoots of two spring wheat (Triticum aestivum L. em Thell) cultivars limits N assimilation during the grain filling (post anthesis) period. Twice weekly after anthesis NR activities in the flag leaf blade, flag leaf sheath, and first leaf blade below the flag leaf were estimated on field‐grown plants with an in vivo assay. Activity declined during the period in apparent association with senescence of the tissues. In contrast, when NR estimates were made by a modified assay in which no exogenous nitrate was supplied, activity was consistently low. This suggests that relatively little nitrate was available for reduction in these tissues although NR enzyme appeared to be there.

The cultivars accumulated approximately 90% of their total reduced N before anthesis, as estimated by sequential sampling of shoots from the same plot area from which the NR samples were taken. Nitrogen accumulation after anthesis was predicted from the enzyme activities measured by both assay methods. Nitrogen accumulation predicted from the NR activities measured when nitrate was included was substantially greater than the accumulation actually observed. Our results suggest that the minimal accumulation of reduced N after anthesis by the cultivars in this study should not be attributed to the level of NR enzyme. It may be more a function of a limitation in a process responsible for supplying nitrate to the enzyme.
Protein and Amino Acid Profiles of Normal and Yellow‐Berry Bread Wheat1
Authors: Waines J. G. , Labanauskas C. K. , Handy M. F. , Gill B. S. , Lehman W. F.
Published: July 2010

Values for nitrogen concentrations in yellow‐berry kernels of bread wheat (Triticum aestivum L. em Thell.) varied from 91.6 to 72.9% of those for normal kernels of the same cultivar. Values for total amino acid concentrations in whole‐wheat flour of yellow‐berry kernels were less than those of whole‐wheat flour of normal kernels. When the values were expressed as concentrations of amino acid per gram protein, those for lysine and threonine were higher in yellow‐berry kernels than in normal kernels, and the differences were significant and highly significant, respectively: that for glutamic acid was significantly lower in yellow‐berry kernels than in normal kernels. Isoelectric focusing patterns of albumins and gliadins from the two kinds of kernels showed no differences. Additional index
Inheritance of Resistance to Pea Seed‐borne Mosaic Virus in Lentils1
Authors: Haddad N. I. , Muehlbauer, F. J. , Hampton R. O.
Published: July 2010

The USDA collection of lentils (Lens culinaris Medic.) was screened for resistance to pea seed‐borne mosaic virus (PSbMV); PI lines 212610, 251786, 297745, and 368648 were found to be immune. After inoculation and an incubation period the virus was not recoverable by local lesion assay from the resistant lines, nor did the resistant lines develop symptoms or transmit the virus through seeds from inoculated plants. Two immune lines were used to study the inheritance of resistance. The F2 progenies of crosses between PI 368648 and the susceptible cultivars ‘Tekoa’ and ‘Precoz’ segregated in a 3:1 ratio of susceptible to resistant plants, indicating that resistance was conferred by a single recessive gene. All F2 progenies of a cross between PI 368648 and PI 212610 were 100% resistant, which indicated that the same recessive gene was present in the two sources. We propose that the gene symbol sbv be used to designate resistance to PSbMV in lentils. The PSbMV‐infected plants could be identified under a range of temperatures. However, symptom expression was more severe at 24 and 30 C than at 18 C. Symptoms at all temperatures included stunting, leaf curling, and leaf size reduction. Vein clearing, tip bending, and tip necrosis occurred at 24 and 30 C, whereas, premature plant death only occurred at 30 C.
Haploid and Diploid Callus from Cotton Anthers1
Authors: Barrow Jerry , Katterman Frank , Williams Dale
Published: July 2010

We have initiated and subcultured large quantities of callus tissue from the anthers of two species of cotton, Gossypium barbadense L. and G. hirsutum L. A liquid medium was developed and cell suspension cultures were generated from anther‐derived callus from G. hirsutum. Cytological examination was made only on anther callus from G. hirsutum and the preponderance of the tissue was diploid (2n=4x=52). Liquid suspension cultures from anther callus were also found to be primarily diploid. However, 13 cultures that grew more than four times faster than 527 diploid cultures had 83% haploid cells. Therefore, haploid tissue was produced in 2 to 3% of the anthers, and it grew obscurely within the diploid callus. The haploid tissue was identified and selected by its rapid growth rate in liquid culture.
Alfalfa Yield, Specific Leaf Weight, CO2 Exchange Rate, and Morphology1
Authors: Hart R. H. , Pearce R. B. , Chatterton N. J. , Carlson G. E. , Barnes D. K. , Hanson C. H.
Published: July 2010

Alfalfa (Medicago sativa L.) clones differ widely in CO2 exchange rates (CER) and in specific leaf weights (SLW); CER is correlated with SLW. If high forage yield could be shown to be associated with high CER, selection for high CER or SLW should result in improved forage yield.

We selected plants with extremely high or extremely low SLW from several alfalfa populations and measured forage yields of clones propagated from these plants in the greenhouse and the field. Stems/plant, length and weight of the longest stem, the percentage of leaves on the longest stem, and SLW were determined at some harvests.

The 116 clones studied in four experiments exhibited a wide range of CER, SLW, morphological characteristics, and yield. Correlations between yield and CER or SLW were small and in some cases negative. Yield per dm2 of leaf area was more closely correlated with CER (r = 0.26 to 0.28) than was total yield. SLW and CER were positively correlated in all experiments (r = 0.50 to 0.92). Yield was much more closely correlated with stem number, stem weight, and estimated leaf area (r = 0.60 to 0.91) than with CER or SLW. Neither CER nor SLW is an effective selection index for forage yield in alfalfa.
Photoperiodic Alteration of Dry Matter Partitioning and Seed Yield in Soybeans1
Authors: Raper C. David , Thomas Judith F.
Published: July 2010

Soybeans [Glycine max (L) Merr. ‘Ramsom’] were grown in controlled environment rooms to evaluate the effects of photoperiod during the seed‐fill period on dry motter partitioning and seed yield at maturity. Plants were grown in sand culture with a complete trient solution and at day/night temperatures of 22/18, 26/22, and 30/26 C. Initially, plants were grown under non‐inductive long‐day photoperiods. At the sixth node stage of development, the plants were moved to inductive short‐day photoperiods for 25 days until the beginning of podfill. Four plants at each temperature were then returned to the long‐day photoperiod until full pod maturity and four were retained under the short‐day period until maturity. At all temperatures, the ratio of vegetative to reproductive weight at full pod maturity was increased under the long‐day photoperiod. Pod weight was unaffected by photoperiod but seed weight and total seed yield were restricted by the long‐day photoperiod at the two higher temperatures. However, seed size and yield were greater for the long‐day photoperiod at the 22/18 C temperatures.
Apparent Growth Inhibitor in Hulls of Peanut1
Authors: Robinson E. L. , Burdick D.
Published: July 2010

Because peanut [Arachis hypogea (L.)] hulls have been suggested as a substitute for sphagum moss in starter cubes for seedling growth, we tested extracts from variously treated hulls for their effects on germination and seedling growth. In these preliminary studies, we found a water‐soluble, inhibitory substance that was inactivated by heat. The substance appeared to be an inherent part of the hull of some peanut types. Inhibitory activity was not detected in all lots of peanut hulls tested, but use of untreated hulls in starter cubes would not be advisable until a means to consistently remove the inhibitory substance has been found.
Yield Stability of Soybean Mixtures and Multiple Pure Stands1
Authors: Walker A. K. , Fehr W. R.
Published: July 2010

The objective of our study was to determine the number of high‐yielding soybean [Glycine max (L.) Merr.] cultivars that should be grown in mixtures or in pure stands to obtain high yield and stability of production across environments. Eighty entries prepared from 28 high yielding pure lines with a 10‐day range in time of maturity were evaluated during 1975 and 1976 at six locations in Iowa. Yields in the 12 environments ranged from 11.1 to 39.2 q/ha. The entries, which included 14 of the 28 pure lines and six mixtures each for 2 to 10, 12, and 14 components, represented 12 levels of heterogeneity.

There were no significant differences in yield between the mixtures and the mean of their components grown in pure stands (multiple pure stands). Regression of entry yields on an environmental index indicated that none of the pure lines, mixtures, or multiple pure stands had regression coefficients significantly different from each other or from unity. Average mean squares for deviations from regression were slightly smaller for mixtures than multiple pure stands and tended to decrease until mixtures had eight or more components. It was not possible, however, to define precisely the number of pure lines needed for stable production because mean squares for deviations from regression were more variable within than among levels of heterogeneity. Stable production depends on the particular cultivars or mixtures chosen as much as on the number involved. The choice between mixtures and multiple pure stands would depend on the yield of cultivars resistant to sporadic pest and soil problems, length of harvesting period desired, and the need to save pure seed.
Cotton Cultivar and Boll Maturity Effects on Aflatoxin Production1
Authors: Sun Stella , Jividen G. M. , Wessling W. H. , Ervin Mary Lou
Published: July 2010

Commercial cotton cultivars (Gossypium hirsutum L.) were evaluated for aflatoxin production in 1974, 1975, and 1976 crop seasons. Bolls were inoculated at different levels of maturity with Aspergillus flavus Link. In 1974, the fungus produced aflatoxin in bolls of all 11 cultivars infected, but ‘Acala SJ‐1’ and ‘Acala 1517’ were better subtrates for the production of aflatoxin than ‘Delcott 277’, ‘Stoneville 213’, ‘Coker 711’, ‘Stoneville 751‐N’, or ‘Deltapine SR‐1’. In each of the 3 years, the fungus produced the greatest amount of aflatoxin in bolls of most cultivars inoculated at 30 days post‐anthesis, but less in 20‐day inoculated bolls and the least in 40‐day inoculated bolls. ‘Stripper 31’ was a notable exception in 1975 became A. flavus produced most aflatoxin in bolls of this cultivar inoculated 40 days post‐anthesis. In 1976, 20‐day and 30‐day post‐anthesis‐inoculated bolls were harvested 10, 15, 20, 25, and 30 days after inoculation. Aflatoxin was found in closed bolls 10 to 20 days after inoculation. The amount of aflatoxin increased with each subsequent time interval. The presence of aflatoxin in closed bolls demonstrated that bolls do not have to open to have toxin formation. A single pink bollworm [Pectinophora gossypiella (Saunders)] exit hole, which serves as the entrance hole for the fungus, allows enough oxygen penetration into the boll for aflatoxin formation.
Dry Matter Accumulation Patterns in Indeterminate Phaseolus vulgaris L. Cultivars1
Authors: Robitaille Henry A.
Published: July 2010

It has not been determined how extent of continued vegetative growth after flowering in dry bean (Phaseolus vulgaris L.) affects yield potential. Since indeterminate dry bean cultivars range in stature from short and erect to tall vines, it is important to determine to what extent continued shoot elongation after flowering influences dry matter partitioning into developing pods. ‘Monteigao Fosco’ (MF), ‘Rico 23’ (R23), and ‘Ricopardo’ (RP) are erect, semi‐erect, and vining indeterminate cultivars, respectively, with approximately equal maturity dates. Central leader length, total shoot length, numbers of lateral shoots, nodes, flowers, pods, and leaves, and dry wt of shoots, leaves, and pods were determined for each cultivar at biweekly sampling dates beginning at the second trifoliate leaf stage and continuing until maturity. At initial flowering, MF, R23, and RP had reached 88, 46, and 57% of central leader length, 53, 53, and 31% of total shoot growth, and subsequently developed two, six, and seven additional nodes, respectively. MF developed more lateral shoots than both R23 and RP. Despite these variations in growth habit, dry matter accumulation patterns were similar for the three cultivars, suggesting that plant type may not be an important factor in determining yield potential.
Selection for Yield and Yield Components in Wheat1
Authors: McNeal F. H. , Qualset C. O. , Baldridge D. E. , Stewart V. R.
Published: July 2010

From an F2 population of about 700 plants from across of two spring wheats (Triticum aestivum L.) CI 13242 and ‘Thatcher,’ 10 plants were selected for maximum expression of grain yield per plant, spike number/plant, kernel number/spike, spikelet number/spike, and kernel weight. In each subsequent generation through the F8, selection lines for each of the five characters were advanced by selecting the 10 plants with the highest value from a population of about 400 plants. A performance trial was conducted at three locations in 1 year with five generations (F4 to F8) of each of the five selection lines and the two parents. Yield and yield components were evaluated and compared with midparent values and as linear regressions on generation number. Selection for kernel weight and kernels/spike at the F8 generation gave 11 and 16% increases in yield over the midparent, whereas direct effects of selection for these two characteristics were 13 and 10%, respectively. Direct effects of selection for grain yield and spikes/m2 at the F8 generation were significantly lower than the midparent (—13 and —7%). Nonsymmetrical correlated responses for increased kernel weight with selection for high kernel number and for decreased kernel number with selection for high kernel weight were large and unexpected. Spike number per plant was not an effective selection criterion for increasing spike number per m2 or grain yield. Only 3 of 20 regression coefficients for response in the F4 through F8 generations were significant, compared with 15 of 20 significant differences from the midparent at F8. Apparently selection was effective in the F2 and F3 generations (13 of 20 midparent differences were significant at F4), with little subsequent response. In this population, kernel weight and kernel number per spike were good characters for indirect selection for yield improvement.
Lysine and Protein Characterization of Spontaneous Shrunken Endosperm Mutants of Barley1
Authors: Ullrich S. E. , Eslick R. F.
Published: July 2010

Compana sex1, seg3 and seg4, Betzes seg1 and seg2, Ingrid seg6 and seg7, Glacier seg5, High Amylose Glacier amol and Hiproly lysl, spontaneous shrunken endosperm or low kernel weight mutants of barley (Hordeum vulgare L.), were compared to their normal isotypes for kernel weight, protein, and lysine contents. All mutants were lower in kernel weight and most were higher in protein and lysine contents than respective normal isotypes indicating that at least seven new mutants should be added to the list of known “high lysine” mutants of barley, and confirming the observation in barley that low seed weight and high lysine are closely associated. Mutants sex1, seg4, amol and perhaps Hiproly show the most promise of overcoming the detrimental high lysine‐low kernel weight association in a breeding program.