bluuebunny/crossref_metadata_2025 huggingface dataset:
Manifestations of Hybrid Vigor in Grain Sorghum and the Relations Among the Components of Yield, Weight per Bushel, and Height1
Authors: Kambal A. E. , Webster O. J.
Published: July 2010

One hundred and ninety grain sorghum hybrids, produced by crossing 10 male‐sterile lines with 19 fertility restorers, were compared with their parents over 2 years at Lincoln, Nebraska. The hybrids average 20% higher in grain yield, 0.5 lb. heaver in weight per bushel, 4.5 inches taller, and 2.5 days earlier than the mean of the parents. The yield advantage of the hybrids resulted mainly from increases in nmnber of seeds per head and, to a lesser extent, from increases in seed weight. Heterosis for yield was not expressed as increased tillering.

The slight increase in weight per bushel resulted front slightly greater heterosis for seed weight than for seed volume.

The hybrids were taller than their parents because they had longer stems, peduncles, and heads. Heterosis for stem length was manifested in the length rather than the number of internodes. It seems that the factors controlling the number and length of internodes differ from those determining peduncle and head lengths.

The grain produced by the hybrids averaged lower in protein content than that produced by the parents. However, because of their higher yield, the hybrids averaged 16% higher than the parent in crude protein per acre.
Photophosphorylation in Barley1
Authors: Kleese R. A.
Published: July 2010

Extraction and assay conditions for obtaining barley chloroplasts capable of carrying on photophosphorylation are presented. Except for response to pH and concentration of ADP, these conditions are similar to those reported for other species.

Genotypic differences in rates of photophosphorylation in barley were demonstrated. In light of the limited number of varieties studied, it is anticipated that considerably more genetic variation in rate of photophosphorylation may be found in barley than was observed in this study.
Inheritance of Pericarp Types, Sterility, and Dwarfhess in Several Safflower Crosses1
Authors: Ebert W. W. , Knowles P. F.
Published: July 2010

Investigations were conducted to further elucidate information available regarding the inheritance of pericarp and anther dehiscence characteristics of safflower. Previous reports that reduced pericarp and delayed another dehiscence are controlled by the recessive gene th and that striped seed is controlled by the recessive gene stp, which is inherited independently of th, were confirmed. An intermediate expression of pericarp thickness, where the hull was thin at the upper end only, was determined to be controlled by the same major gene th. In certain genotypic backgrounds the expression of the th gene is modified considerably with regards to pericarp development without materially affecting delayed anther dehiscence. No evidence of linkage was observed between the independent genes, th and stp, and several well known genetic markers in safflower.

Since no recombination was observed between extremely thin pericarp and delayed anther dehiscence the hypothesis was proposed that these characteristics were the pleiotropic manifestations of the thin‐hull gene.

It is assumed that spontaneous single‐gene mutations were responsible for the presence of sterile and dwarfed plants found in the progenies of one cross. Although the possibility of new recombinations and not mutation was not ruled out entirely, the evidence available does suggest that hybridization between certain strains of safflower may stimulate mutations.
Effects of Vigor of S1 Lines and Seeding Rates on Yield and Final Stand of an Alfalfa Two‐Clone Combination Admixed with Different Percentages of S1 Seed1
Authors: Carnahan H. L. , Paden R. N.
Published: July 2010

An alfalfa 2‐clone F1 combination was admixed with each of 5 S1 lines at 5 dilution percentages and seeded at 3 rates. Forage yields for a 2‐year period at Reno, Nevada, indicated (a) as little as 10% selfed seed in admixtures depressed yield significantly; (b) differences in vigor of S1 lines contributed to a significant dilution ✕ Sl's interaction; and (c) seeding rates did not interact materially with dilutions.

Final stand indicated that competition generally was more operative at higher seeding rates and in admixed populations than in either the 2‐clone combination or the S1 plots. We concluded that yield of a 2‐clone combination is dependent upon (a) yield of the hybrid; (b) yield of the Sl's from the parents; (c) amount of selfing that occurs in producing the seed of a 2‐clone combination; and (d) the amount of compensation by the hybrid component of the combination. Theoretical advantages and disadvantages of hybrids vs. 2‐clone combinations were discussed.
Clonal and Progeny Evaluations in Two Populations of Tall Fescue (Festuca arundinacea Schreb.)1
Authors: Thomas J. R. , Frakes R. V.
Published: July 2010

Clonal evaluation and five progeny testing methods (S1, open‐pollinated, polycross, single‐cross, and F2) were compared for three traits in two populations of tall fescue for 3 years. The three traits were plant height, seed yield, and seed weight. The progeny tests were compared by selecting the best parental clones on the basis of each of the six tests using Duncan's multiple range test, then observing which methods led to the selection of the same parental clones.

The results indicated: (1) there was generally good agreement among years for the traits studied; (2) use of clonal evaluation with 1 year's data might result in loss of equal clones, but seldom would obviously superior clones be discarded; (3) clonal evaluation and Sj and single‐cross progeny tests generally gave similar results, while the open‐pollinated, polycross, and F2 progeny tests were generally the least useful for detecting differences among the clones; and (4) clonal evaluation would be quite useful in evaluating large numbers of clones for synthetic varieties, but single‐crosses should be made and tested to determine the best two clone combinations.
Rotenoid Content and Growth Characteristics of Tephrosia vogelii as Affected by Latitude and Within‐Row Spacing1
Authors: Barnes D. K. , Freyre R. H. , Higgins J. J. , Martin J. A.
Published: July 2010

Four varieties of the tropical legume, Tephrosia vogelii, a source of the natural insecticide rotenone, were tested for one season at three locations to investigate the effect of latitude and plant spacings on several growth characteristics and on total rotenoid accumulation in the leaves. Planting locations included Mayaguez, Puerto Rico, 18° N; Clemson, S. C., 34° N; and Glenn Dale, Md., 38° N. Planting distances included 1 m between rows and three spacing distances (15 to 23 cm, 30 to 38 cm, and 53 to 61 cm) between plants within the row.

Rotenoid (rotenone and related compounds) accumulation patterns varied among varieties, but the relative rating of varieties for percentage rotenoid content per unit of dry weight was not influenced by planting distance or latitude. Plant growth characteristics such as plant height, leaf‐stem ratio, and total yield of stems and leaves were significantly influenced by variety, within‐row spacing, and location. Since these growth characteristics are associated with total rotenoid production per hectare, within‐row plant spacing which provides 30,000 to 37,000 plants per hectare is suggested as the optimum planting pattern for T. vogelii. Maximum yields of total rotenoids obtained at Clemson, S. C., Glenn Dale, Md., and Mayaguez, P. R., were 82, 104, and 185 kg/ha, respectively.
Evaluation of a Population of Soybean Genotypes With Implications for Improving Self‐Pollinated Crops1
Authors: Hanson W. D. , Probst A. H. , Caldwell B. E.
Published: July 2010

Eight improved soybean lines constituted the base of a random intermating population from which a population of homozygous genotypes was obtained. A family structure was maintained in the selfing generations. The genetic variability found was generally larger than that reported for two parent crosses. Considerable epistatic variability was suggested for seed yield, maturity, and percent mottling. The relative proportions for genetic variability partition were not affected when levels of environmental sampling, ranging from within environments to among environments in Maryland and Indiana, were considered. Concepts for improving a base population of homozygous lines through recurrent selection and intermixing were developed. Such an intermating system provided for stepwise improvement yet minimized the coefficient of parentage among breeding lines. The expected improvement in the base population resulting from intercrossing of the superior lines was developed. Selecting the top 20 lines (5%), intermating, and selfing in this study yielded a predicted 235 kg/ha (3.5 bu/A) gain over the base population mean. With epistatic variability, as suggested for seed yield, considerations for isolating unique genetic combinations become important. The importance of creating populations where geneticrecombinations could potentially occur was discussed.
Inheritance of Relative Phosphorus Accumulation in Corn (Zea mays L.)1
Authors: Barber W. D. , Thomas W. I. , Baker D. E.
Published: July 2010

Analysis of corn leaf tissue has revealed significant differences among corn inbreds and corn hybrids for the concentrations of various chemical elements, including phosphorus. An investigation was initiated in an attempt to assess the consistency and nature of the apparent genetic control of phosphorus accumulation in corn.

Experiments designed to study the inheritance of differences in phosphorus concentration, measure accumulation differences in seedlings, and assess the effects of variations in soil phosphorus on accumulation differences were conducted in 1962 and 1963. Data from these experiments verify the existence of genetically controlled phosphorus accumulation variations and indicate that at least two genetic factors are involved with the possibility of dominance for the lower phosphorus level in at least one of these factors. There were no apparent relationships of phosphorus accumulation with the accumulation of other elements, including K, Ca, Mg, Mn, Fe, Cu, B, Al, Sr, and Zn. No noticeable effects of soil phosphorus level upon the expression of accumulation differences was revealed. This study also failed to indicate any relationship of leaf phosphorus concentration to grain yield.

Genotypes which accusnulated highly significant different amounts of phosphorus in mature leaf tissue were little or no different as seedlings when grown in pots.
Preliminary Classification of Polysaccharide Freezing Inhibitors1
Authors: Olien C. R.
Published: July 2010

Structure of ice masses which form in the vicinity of the cell walls within living plants can affect survival of hardy winter cereals. Soluble polysaccharides which affect ice structure previously were classified on a basis of equilibrium and kinetic relationships which occur as the solutions are frozen in films on cellulose. A simpler method of classifying cell wall polysaccharides on a relative basis is presented. The method is based on interaction of the polymers with an expanding ice lattice as the liquid solution slides across the ice‐liquid interface.
Breakup of Initial Linkage Blocks Through Intermating in a Cotton Breeding Population1
Authors: Miller P. A. , Rawlings J. O.
Published: July 2010

Restricted character recombination was observed in the F2 generation of a cross between two contrasting inbred lines of cotton. If initial linkage blocks were an important cause of the restricted recombination, intermating for several generations should break up such linkages and increase genetic recombination. Beginning with the F2 generation, the population was maintained for six successive generations in an isolation block where the natural mating system was mixed intermating and selfing (approximately 50% self‐pollination). The population was resampled to study the effects of intermating on genetic recombination for seven quantitative traits. Genotypic variances decreased for six traits for which coupling‐phase linkages would be expected to predominate and increased for one trait for which repulsion linkages might have been more important. Genotypic correlations between traits tended to shift toward values observed in populations assumed to be more nearly at linkage equilibrium. These observed changes conform with expectations that intermating dissipates initial linkage diseqilibrium. Changes in gene frequency which occurred during intermating for some of the traits, however, confounded the interpretation of the observed results.
Variation and Covariation in a High Oil Population of Corn (Zea mays L.) and Their Implications in Selection1
Authors: ElRouby Mohamed M. , Penny L. H.
Published: July 2010

Sixty‐four half‐sib families, each containing four full‐sib families, were grown in replicated trials in five environments. Data were collected for silking date, plant and ear heights, kernel size, lodging percentage, shelling percentage, oil percentage, yield of grain, and yield of oil. Estimates of additive and dominance variances were calculated for each trait, and these variance estimates were used to predict the genetic gain from different selection methods. Phenotypic and additive genetic correlations among traits were calculated.

All estimates of additive genetic variance were significantly greater than zero. None of the estimates of dominance variance was significant except for yield of grain in one environment. Mass selection appeared to be the most effective method of selection for higher oil percentage in this population, but recurrent selection for general combining ability would be the most effective method for yield of grain and yield of oil. The only traits significantly correlated with oil percentage were silking date and yield of oil. A selection index for improving yield of oil appeared to have little advantage over selection for yield of oil alone.
Nuclear Magnetic Resonance Analysis for Oil in Soybeans, Glycine max ( L.) Merrill, with Implications in Selection.1
Authors: Brim C. A. , Schutz W. M. , Collins F. I.
Published: July 2010

Nuclear magnetic resonance spectrometry was used to characterize intragenotypic between‐ and within‐plant variability for percent oil in soybeans. Differences among pods and among plants were the largest source of withinline variability in field and greenhouse tests, respectively. Oil content was found to be inconsistent for different positions on the plant. For the environmental conditions of this study, the error variance of a line mean was minimized by sampling at the intermediate flowering node in the field and either the intermediate or basal node in the greenhouse. Two pods (two seeds/pod) these positions were sufficient to classify high and low oil plants with 94 and 86% accuracy in the field and greenhouse, respectively. Sampling additional plants or pods per plant should increase the accuracy of classification for selection purposes.
Allelism for Awn Length, lk2, in Barley (Hordeum species)1
Authors: Eslick R. F. , Hockett E. A.
Published: July 2010

Short‐awned gene, from seven sources are drown to be allellic and are properly designated as lk2 Ik3 on chromosome I.
Photosynthesis in Sugarcane Varieties Under Field Conditions
Authors: Irvine J. E.
Published: July 2010

Rates of photosynthesis per unit of leaf area (P) differed among 10 varieties of sugarcane in a replicated field test. The variety ‘F. 36‐819’ was significantly higher in P than all others and the hybrids of Saccharum officinarum were lower than the interspecific hybrids. A correlation between P and leaf thickness (0.77) and between P and porosity (0.57) was found. Leaf thickness and porosity are more readily determined than P and may prove useful in the search for sugarcane varieties of higher photosynthetic potential. No correlation was found between P and stomatal number, stomatal length or leaf density thickness.
Interspecific Hybridization in Trifolium1
Authors: Katznelson J.
Published: July 2010

The interspecific relationships among several Trifolium spp. in the section Calycomorphum were studied. Crosses involving T. israeliticum, T. globosum, and T. pauciflorum failed to produce hybrid seed. Crosses among T. subterraneum, T. eriosphaerum, and T. pilulare gave varying results. Complete interspecific sterility was most common; however, 3 F1 plants (1 plant from the T. eriosphaerum ✕ T. subterraneum cross and 2 plants from the T. pilulare ✕ T. subterraneum cross) survived till after flowering. The F1 plants had morphological characteristics of both parents. F2 seeds were formed, probably through backcrossing, in two male sterile interspecific hybrids, T. subterraneum ✕ T. eriosphaerum and T. pilulare ✕ T. subterraneum. Fertility was partially restored in the F3 and F4 lines, although several fertile F3 plants produced sterile progenies. The results suggest that this group is young and shares common morphogenetical and physiological systems because interspecific hybrids can be obtained by conventional methods. Morphological specialization is more advanced than the reproduction barriers because the taxa involved are self‐fertilized annuals and are isolated spatially.
Barley Yellow Dwarf Studies in Wheat (Triticum aestivum L.). I. Yield and Quality of Hard Red Winter Wheat Infected With Barley Yellow Dwarf Virus1
Authors: Fitzgerald Paul J. , Stoner Warren N.
Published: July 2010

Barley yellow dwarf virus infection caused highly significant yield losses in three varieties of hard red winter wheat. Yield reductions resulted from a reduced number of heads per foot of row, fewer kernels per head, and reduced kernel weight.

Fall‐infection resulted in greater yield losses than spring‐infection. Differential winterkill due to fall‐infection did not appear to account for yield differences.

Height of the plants and number of heads per foot of row also showed highly significant reductions caused by the disease, but differences due to time of infection were not significant.

Milling and baking quality were somewhat adversely affected by the BYD disease, but differences between healthy and diseased samples were generally small and inconsistent among the varieties. Samples from diseased plants in all varieties were poorer or just equal to the samples from healthy plants for test weight, 1000‐kernel weight, and kernel size. Flour protein percentage was slightly higher in grain samples from diseased plants in all varieties.
Further Evidence of Epistasis in Single and Three‐Way Cross Yields of Maize (Zea mays L.)1
Authors: Sprague G. F. , Thomas W. I.
Published: July 2010

Six unselected lines from the variety ‘Midland’ (Zea mays) were compared in single‐ and three‐way crosses to provide estimates of the influence of epistasis on grain yield. Significant estimates of epistasis were obtained involving five of the six lines. In spite of the significance of the estimates, epistatic effects are not considered to be of major importance.
Relation of Intra‐Population Genetic Effects to Performance of S1 Lines of Maize1
Authors: Lonnquist J. H. , Castro G. M.
Published: July 2010

Intra‐population genetic variances were obtained using design I matings in high and low selected S1 lines (F2 populations) representing extremes from a total of 169 KrugIII synthetic lines on the basis of evaluation as a) S1 per se, b) testcrosses with the parental population and c) testcrosses with an unrelated population. The experiments were grown over a 2‐year period. There appeared to be more additive than non‐additive genetic variance for yield within lines selected as high yielding in testcross performance whereas the reverse was true in those selected as high yielding on the basis of line per se performance. Low selected S1 lines exhibited generally, more nonadditive than additive genetic variance. Standard errors were of such magnitude as to preclude establishment of clear cut differences among variance components. Performance trials of the derived synthetics failed to show superiority for any of the three line evaluation procedures.
Influence of Pericarp on Differential Drying Rate in “Mature” Corn (Zea mays L.)1
Authors: Purdy J. L. , Crane P. L.
Published: July 2010

Removing the pericarp from kernels of “fast” and “slow” drying corn (Zea mays L.) hybrids resulted in almost identical rates of moisture uptake or loss. Intact kernels of the same hybrids demonstrated differing rates of moisture uptake or loss. Treatment of kernels with a potassium cyanide “killing” solution resulted in no change relative to “faster” or “slower” rates of water loss. This suggests that the differential rates of water loss were due to the physical structure of the pericarp and not to metabolic processes within the kernel. The faster drying rates were associated with thinner pericarps and greater permeability.
Effects of Temperature and Photoperiod on Metabolic Changes in Alfalfa in Relation to Cold Hardiness1
Authors: Shih S. C. , Jung G. A. , Shelton D. C.
Published: July 2010

Investigations were conducted to evaluate the effects of temperature and photoperiod on metabolic changes during development and maintenance of cold hardiness of two alfalfa (Medicago sativa L.) varieties varying widely in inherent cold hardiness. Cold temperatures appeared to be of primary importance for development and maintenance of cold hardiness, whereas both temperature and pbotoperiod played important roles in the metabolic processes.

The content of protein, RNA, or DNA was positively associated with development and maintenance of cold hardiness. The content of protein or RNA located in microsomes was more closely associated with cold hardiness than was the content of these constituents located in other subcellular fractions. Tissue pH was higher at the peaks of cold hardiness than at other times. The hardy ‘Vernal’ variety contained more protein, RNA, or DNA than the nonhardy ‘Arizona Common’ variety during development and maintenance of cold hardiness.
Recurrent Selection for European Corn Borer Resistance in Maize1
Authors: Penny L. H. , Scott Gene E. , Guthrie W. D.
Published: July 2010

Three cycles of recurrent selection for leaf‐feeding resistance to the European corn borer [Ostrinia nubilalis (Hübner)] were evaluated in five synthetic varieties of maize. A group of S1 lines fom the original population and from the populations derived from each cycle of selection in each variety were grown in field trials. Each line was manually infested with corn borer eggs and rated for borer leaf feeding. Two cycles of selection were sufficient to shift the frequencies of resistance genes to a high leval in all varietties. Three cycles produced essentially borer‐resistant varieties.
Relation of Coleoptile Structure to Coleoptile Strength and Seedling Emergence Under Compacted Soil Conditions in Six Varieties of Winter Wheat1
Authors: Kolp B. J. , Miller D. G. , Pratt G. A. , Hwang Shou‐jen
Published: July 2010

Coleoptile length under soil compaction as a percent of length under no compaction was used to measure coleoptile strength. Varieties that produced long coleoptiles under no compaction produced the longest coleoptiles under compaction. Correlations were found between cell diameter and several morphologic structures of the coleoptile. As soil compaction increased, coleoptile length was reduced; total plants emerged and rate of emergence also decreased.
Induction of Polyploidy in Linum Species1
Authors: Yermanos D. M. , Gill K. S.
Published: July 2010

Colchicine was evaluated at six concentrations (0.0125, 0.025, 0.05, 0.1, 0.2, and 0.4% in water) for the induction of polyploidy. Three Linum species, L. usitatissimum (var. ‘Imperial’ and ‘Abyssinian yellow’), L. angustiSolium, and L. narbonense, were treated at different stages of development. The most effective treatment was 0.1% colchicine for 6 hours on germinating seedlings. Effectiveness of the treatments depended on species, concentration, duration of application, and duration Χ concentration interaction. Polyploids could be identified 3 weeks after treatment by their increased stomata size and later by their larger flower, seed, and pollen grain size.

Meiotic behavior was studied in auto‐tetraploids of L. usitatissimum, L. angustifolium, L. africanum, L. altaicure, L. grandifiorum, L. maritimum~ L. narbonense, L. rigidum, and L. tenuifolium. A high frequency of quadrivalents was formed by all species at meiosis involving 33 to 71% of the chromosome complement. Chlasmata frequency in tetraploids was lower than in diploids. Pollen viability and number of seeds per capsule were lower in all auto‐tetraploids, but seed and capsule size were larger. Oil content and degree of unsaturation were lower in tetraploids, while moisture content of the seed was higher.
Influence of Stem Diameter on Oviposition Preference of the Alfalfa Weevil and Its Importance in Breeding for Resistance1
Authors: Norwood B. L. , Barnes D. K. , VanDenburgh R. S. , Hanson C. H. , Blickenstaff C. C.
Published: July 2010

This investigation consisted of two laboratory experiments which were designed to study the influence of stem size on oviposition preference of the alfalfa weevil, and the effect of that interrelationship on selection for resistant plants with large stems. F1, F2, and S1 progenies were studied.

Alfalfa strains and single crosses differed significantly for number of eggs per stem and stem diameter. In the two experiments the mean number of eggs per stem and stem diameter were correlated (r = .91**, 15 df and r .71**, 26 df). Plants with small stem diameters tended to have less oviposition. However, in progenies of several plants oviposition preference was not entirely dependent on stem diameter.

Available evidence suggested that a breeding program, based on selecting plants with low oviposition preference and large stem diameter, might result in significant progress in developing an agronomically acceptable variety with resistance to oviposition. HOwever, this nonpreference type of resistance would have to be evaluated under field conditions before its potential economic value could be ascertained.
Male Gametophyte of Zea mays L. I. Some Factors Influencing Fertilization1
Authors: Walden D. B.
Published: July 2010

Geneticists and breeders have standard procudures of pollen and ear shoot preparation for controlled pollination of corn, but meager data are available to quantify comparisons of techniques. Three experiments were conducted in which limited, controlled numbers of pollen grains were applied at various times to prepared and unprepared ear shoots of a single‐cross hybrid, Oh 51At ✕ B8. Genetic constitution of pollen and ovule parents permitted detection of contaminant kernel.

Cutting to a brush the silks on ear shoots resulted in significantly more seed set than using uncut or freshly cut ear shoots. Hour of pollination and the time required for pollen tube establishment in the distal 3 cm of silk were tested, Five to 10 hours were required for 3 cm of pollen tube growth; pollinations made before 2 PM required 5 to 7 hours, while pollinations made after 4 PM until 10 PM required successively longer periods. The longevity of corn pollen was estimated. Viable pollen grains were recovered after 292 hours of storage at + 2 C. Pollen may be shipped around the world in a viable condition. It was concluded that the techniques used by most corn workers provided optimal opportunity for seed set.
Response of Soybeans to a Carbon Dioxide‐Enriched Atmosphere1
Authors: Cooper R. L. , Brun W. A.
Published: July 2010

Two soybean varieties were exposed to 350 and 1350 ppm CO2 from seedling to maturity in Mylar chambers in the greenhouse. There was a marked increase in plant growth in the CO2 atmosphere at a concentration of 1350 ppm. Seed yields were increased 57% in the variety ‘Hark’ and 40% in the variety ‘Chippewa‐64’. The increase in seed yield was primarily due to an increase in the number of pods per plant. Many of the new pods were born on the longer branches in the CO2 enriched atmosphere.
Studies of the Physiological Basis for Yields Differences. III. Genetic Variation in Photosynthetic Efficiency of Phaseolus vulgaris L.1
Authors: Izhar S. , Wallace D. H.
Published: July 2010

Photosynthetic efficiency was measured by infrared analysis of net CO2 exchange (NCE), using single attached leaves of intact greenhouse grown plants. The leaves were sampled as they approached full expansion or shortly thereafter. One or two measurements of the rate of NCE by primary or trifoliate leaves from several plants were used to estimate the photosynthetic efficiency of a variety. The mean from five observations, usually five different leaves, was used to estimate the genetically controlled potential in photosynthetic efficiency of individual plants from segregating progenies.

‘Michelite‐62’ significantly exceeded the closely related variety ‘Monroe’ by about 9% and ‘Perry Marrow,’ ‘Steuben,’ and 'Red Kidney' by 22%, 35%, and 31%, respectively. Light response curves for Michelite‐62 and Red Kidney were similar, but the net CO2 uptake of Michelite‐62 exceeded that of Red Kidney by about 20% at all light intensities above the compensation point. Light saturations of about 37.7 and 70.0 kilolux, respectively, were obtained with winter and summer grown plants, but the absolute rate of net CO2 uptake was about the same for the two intensities. Below the compensation point, Michelite‐62 evolved more CO2 than Red Kidney. It was determined that the basis for the varietal difference in NCE resides in the reactions of photosynthesis that proceed in the dark rather than those that are light dependent.

The photosynthetic efficiencies of Red Kidney and Michelite‐62, their F1 and F2 progenies, and a backcross to Red Kidney suggested that the genetic mechanism controlling the varietal difference in net CO2 exchange rate is quantitative, that there may be relatively few genes involved, and that there is some dominance for the low photosynthetic efficiency of Red Kidney.
Performance of a Spring Wheat Hybrid, F2, F3, and Parent Varieties at Five Population Levels1
Authors: Briggle L. W. , Cox E. L. , Hayes R. M.
Published: July 2010

The F1 and parents involved in a spring wheat cross (‘Lemhi 53’ Χ ‘HenryΧ) were grown at five population levels under irrigation for 3 years at Aberdeen, Idaho. The F2 was grown in the same experiment for 2 years and the F3 for 1 year.

Little heterosis was evident in plant height.

Heterosis was expressed by the hybrid in grain yield. Performance of the F1 compared to the higher parent was remarkably consistent. The F1 produced 19.5% more grain (over all population levels) than the higher yielding parent in 1963; 19.2% more in 1964; and 16.5% more in 1965. In general, performance of the F2 was lower than that of the F1, and performance of the F3 was slightly lower than that of the F2.

The hybrid produced more spikes per plant than either parent, but no heterosis was expressed in number of kernels per spike. Limited heterosis was evident in kernel size.

F1 and parent plants were slightly taller when grown at the higher plant densities.

Population level had a pronounced effect on yield of grain. An apparent maximum yield was reached by hybrid plants when spaced 1.27 cm (½ inch) apart within rows which were spaced 30.5 cm (1 ft) apart. This represents a seeding rate of approximately 1.9 hectoliters/ha (6‐½ pecks per acre). Yield was not significantly reduced, however, in 2 of the 3 years, when plants were spaced 2.54 cm (1 inch) apart. This is equivalent to a seeding rate of approximately .9 hectoliter/ha (3 ¼ pecks per acre). Cost of hybrid seed could force a producer to reduce his seeding rate to near the latter level. More yield trials of a similar nature are needed before a positive recommendation can be made. Yield of parents was likewise influenced by plant density but was more erratic from year to year than yield of the F1.

Plants grown at low population levels produced more spikes and more kernels per spike than those grown at high levels. Seed size was influenced little by plant density, although there was a trend toward smaller seed at the high population levels.
Basis of Yield Component Compensation in Crop Plants With Special Reference to the Field Bean, Phaseolus vulgaris1
Authors: Adams M. W.
Published: July 2010

Negative correlations among yield components are wide spread among the major crop plants, particularly under various kinds of environmental stress. The correlations are believed to be developmental rather than genetic per se, and are postulated to be caused by genetically independent components, developing in a sequential pattern, that are free to vary in response to either 1) a limited constant input of metabolites, or 2) an oscillatory input of these substances such that input is limiting at critical stages in the developmental sequence.
Influence of Seed Size and Depth of Sowing on the Establishment and Growth of Varieties of Fiber and Oil Seed Flax
Authors: Harper John L. , Obeid M.
Published: July 2010

Small, medium, and large seeds were selected from commercial samples of three oil‐seed and three fiber flaxes (Linum usitatissimum). The varieties were themselves chosen to represent a wide range of seed sizes. In early seedling development both leaf area and dry weight were closely related to seed size, and varietal differences were later imposed on this relationship. Varietal differences in hypocotyl length appeared particularly early. Seedlings from small seeds emerged fastest from shallow (1 cm) and those from large seed from deep sowing (6 cm) irrespective of variety. Seed samples of some varieties contained a sufficient range of seed for some to find their optimum at shallow and others at deep sowing. Advantages of seed size were not generally maintained when plants were grown under the normal density stress of a crop — though significantly taller plants were obtained from the large seeds.
Approach Crossing of Oats (Avena SPP.)1
Authors: McDaniel M. E. , Kim H. B. , Hathcock B. R.
Published: July 2010

The approach crossing technique has been used successfully in making oat crosses at Texas A&M University since 1962. Seed set above 60% has been obtained consistently with this method. Approach crosses between field‐grown and greenhouse‐grown plants were made by cutting the stems of the field‐grown male parent and placing the panicles in water. The detached panicles shed pollen normally for 8 to 10 days, and 74% and 71% seed set were obtained on the female parents in 1966 and 1967, respectively. In 1966, some florets were deliberately damaged to determine the effect of mutilation on seed set. Removing the palea or glumes did not appreciably reduce seed set, but seed set was reduced when the pistil was completely exposed by removing the glumes, lemma, and palea.
Effect of Night Temperature on Photosynthesis of Phaseolus vulgaris L.1
Authors: Izhar S. , Wallace D. H.
Published: July 2010

Net CO2 uptake by 2‐weeks‐old plants of Phaseolus vulgaris L. was found to be reduced by low night temperatures. Plants kept overnight at 10 C exhibited low rates of CO2 uptake for several hours with a gradual return to normal.
Fatty Acid Composition of Corn (Zea mays L.) Oil as Influenced by Kernel Position on Ear1
Authors: Jellum M. D.
Published: July 2010

Five oil samples from each of 3 kernel positions (base, middle, and tip of ear) of 5 ears each of 12 inbred lines were analyzed by gas‐liquid chromatography to determine the effect of kernel position on oil composition. Kernel position had little effect on stearic and linolenic acids. In general, the proportion of palmitic and linoleic acids increased and the proportion of oleic acid decreased in the oil from kernels sampled linearly from the base to the tip of the ear. Kernel position exhibited more consistent and greater influence on oleic and linoleic acids than on palmitic acid. Mp428 and R196 showed no effect of kernel position on oil composition, whereas T202 and Tx39‐16 showed marked effects of kernel position on oil composition. Since random sampling of kernels of certain inbreds can produce considerable variation in o11 composition due to the effect of kernel position, it was concluded that in studies in which single kernels are analyzed, sampling should be restricted to the middle portion of the ear. Correlation coefficients showed that the analyses of small oil samples (single kernels) were comparable to large oil samples (oil from six kernels).
Effect of Potassium on the Content of Amino Acids in Alfalfa and Orchardgrass Grown With NO−3 and NH+4 Nitrogen in Nutrient Solution Culture1
Authors: Macleod L. B. , Suzuki Michio
Published: July 2010

Alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) were grown on nutrient solutions with N at 50 and 250 ppm having 25 or 75% of the N at each concentration supplied as NH+4 and with K at 10, 50, and 250 ppm. Tissue was harvested at the late bud and pre‐boot stages respectively, immediately frozen, and later analyzed for free and conjugated amino acids using a Beckman/Spinco amino acid analyzer.

NH+4 nitrogen was more readily incorporated into the free amino acid pool than the NO‐3 form. Aspartic acid plus asparagine was the predominant amino acid in both plant species, and the ratio of this fraction to glutamic acid plus glutamine reflected the effect of nutrition on nitrogen metabolism. In general this ratio decreased with an increasing K/N ratio in the nutrient solution, and the minimum ratio was found when the K/N ratio was 5/1. At this K/N ratio the alcohol‐insoluble N fraction of total N was maximum. The highest amino acid content was found when the K/N ratio was 1/5.
Isogenic Analysis of Strontium‐89 Accumulation in Barley1
Authors: Rasmusson D. C. , Kleese R. A.
Published: July 2010

The effect of short segments of chromosomes on Sr‐89 accumulation in barley, Hordeum vulgate L., was studied by comparing Sr‐89 accumulation in pairs of isogenic lines. The members of each isogenic pair differed by segments of chromosome estimated to be less than 6 recombination units in length.

Six of the 11 chremosome segments studied influenced Sr‐89 accumulation in grain, stems, or leaves of mature plants or in shoots of seedling plants. In three of the segments the marker gene that served to identify the segment appeared to effect the differential accumulation of Sr‐89. The three genes were those that control hoods vs. awns, long vs. short awn, and naked vs. covered caryopsis. In addition, the chromosome segments identified by the genes controlling two vs. six rows of kernels, black vs. white lemma and pericarp, and purple vs. nonpurple lemma and pericarp had a significant effect on Sr‐89 accumulation.

The study leads to the conclusion that the genetic basis for differences in Sr‐89 accumulation involves a number of genes and is highly dependent on the genetic stocks involved.
Inheritance of Two Female‐Sterile Characters in Dwarf‐Internode Castor (Ricinus communis L.)1
Authors: Brigham Raymond D.
Published: July 2010

Two female‐sterile characters in dwarf‐internode castor were investigated and the inheritance of each appeared to be controlled hy a single recessive gene. The symbols fs1 and fs2 are proposed. In fs1, all pistillate flowers failed to open, and pollen‐fertile staminate flowers tended to remain closed or only partially opened. Perianth segments in pistillate flowers were tightly fused. The epidermal cells of the perianth of flowers of both sexes were abnormally enlarged, resulting in a rough, pebble‐like surface. Normal‐monoecious plants had smooth epidermal layers. The perianths of the pistillate and staminate flowers were 25 and 40% thicker, respectively, in fs1 than in the variety ‘Hale.’

In fs2, pistillate and staminate flowers appeared normal, but capsules failed to enlarge after stigmas were fully exserted. The stigmas dried within a few days, followed by gradual drying of the capsules. Pollen was fertile and stained easily. Cause of the fs2 type female sterility was not apparent in this study.
Resistance of Alfalfa Varieties to the Potato Leafhopper: Seedling Survival and Field Damage After Infestation1
Authors: Webster James A. , Sorensen E. L. , Painter Reginald H.
Published: July 2010

Twenty‐eight varieties and four experimental populations of Medicago sativa L., were tested in the seedling stage for resistance to the potato leafhopper, Empoasca fabae (Harris). The extremely winter‐hardy varieties, ‘Rhizoma,’ ‘Rambler,’ ‘Teton,’ exhibited high seedling survival. In contrast, the nonhardy varieties, ‘African,’ ‘Hairy Peruvian,’ ‘Indian,’ ‘Moapa,’ and ‘Sonora,’ were highly susceptible. The reaction of the Flemish types, ‘Alfa,’ ‘DuPuits,’ and ‘Glacier,’ was similar and intermediate among varieties tested. The Turkistan‐derived variety, ‘Lahontan,’ was highly susceptible. ‘Cherokee’ and the populations MSA‐11 and MSB‐11, which were developed for resistance to yellowing in the field from susceptible source material by recurrent selection, were resistant in greenhouse seedling tests. Experimental synthetics, KS 13 and N. S. 16, rated high for resistance in field and seedling tests.

Field yellowing scores were negatively correlated with seedlings survival in growth chamber tests (r= −0.607*). Repeatability of seedling resistance as determined by survival was demonstrated by a highly significant interannual correlation coefficient (+0.702***) for the unifoliolate growth stage.
Growth of Birdsfoot and Alfalfa. III Changes in Carbohydrates Reserves and Growth Analysis Under Field Conditions1
Authors: Nelson C. J. , Smith Dale
Published: July 2010

The amount of total available carbohydrates (TAC) in the roots of 'Empire' birdsfoot trefoil were lower and the changes were less pronounced than in the roots of 'Vernal' alfalfa at similar growth stages. The difference on a weight basis was much greater than by percentage. Starch, sucrose, glucose, and fructose were the components of the TAC of both species. Relationships among the fractions of the TAC were similar for both species throughout the growing season.

Alfalfa had a higher crop growth rate (CGR) than trefoil except at late stages of maturity when growth of trefoil continued by active upper axillary branching. CGR of alfalfa was higher than trefoil because there was a greater leaf area and it developed faster. Alfalfa was more efficient in the conversion of radiant energy into dry matter because it had a higher leaf area index than trefoil at comparable net assimilation rates. This advantage over trefoil was attributed to a higher photosynthetic rate for alfalfa leaves and to a better light distribution in the taller alfalfa canopy.
Effect of a Generation of Inbreeding on Genetic Variation in Corn (Zea mays L.) as Related to Recurrent Selection Procedures1
Authors: Horner E.S.
Published: July 2010

Response from selection for combining ability is proportional to the genetic variance among test crosses in each cycle. Theoretically, this variance can be increased appreciably by a generation of inbreeding in the population under selection prior to initiation of a new cycle. for a single locus with two alleles, crossing S1 rather than S0 plants with a tester is expected to increase variance among test crosses within intercross progenies (of selected S1 lines from the previous cycle) by 100%, and over the entire population by 50%. Sib‐pollination within intercross progenies would be only one‐half as effective as selfing in this respect. Random mating of the population for one generation would have no effect on test cross variance so far as individual loci are concerned.

Experimental data for grain yield were in good agreement with the expected results based on genetic theory. In populations produced by intercrossing S1 lines, a generation of sib‐pollination within intercross progenies increased the esimate of test cross variance from 0.046 to 0.141 where an increase of 50% was expected. Where S2 lines had been intercrossed, a generation of inbreeding increased test cross variance from zero to 0.172. It was concluded that a generation of inbreeding prior to initiation of a new cycle would be a worthwhile step in recurrent selection programs.
Inter‐Genotypic Competition in Plant Populations I. Feedback Systems with Stable Equilibria in Populations of Autogamous Homozygous Lines1
Authors: Schutz W. M. , Brim C. A. , Usanis S. A.
Published: July 2010

A linear model was developed to describe the competitive effects that may be encountered in populations of soybeans and other autogamous plant species. The model was used to investigate the properties of feedback systems that might develop in populations of autogamous homozygous lines as a result of certain inter‐genotypic interactions. Examples were cited which indicated that competitive feedback mechanisms may be a powerful force in the eventual establishment of stable equilibria in evolving populations. Such populations would have reproductive capabilities greater than the mean of the component genotypes in pure stand. An essential ingredient of the feedback mechanism is the occurrence of overcompensation which results when a genotype's reproductive ability is enhanced in competition with another genotype while depressing the reproductive value of its competitor by a lesser amount. Undercompensation does not lead to a stable equilibrium and appears to be a relatively rare occurrence in nature. Implications of competitive effects and feedback systems in bulk‐population breeding are discussed.
Chromosomal Control of Flour Properties in Three Substitution Sets of Common Wheat (Triticum aestvum L.)1
Authors: Welsh J. R. , Watson C. A. , Green C. W.
Published: July 2010

Three sets of hard red spring wheat substitution lines were subjected to milling and baking tests. The variety 'Chinese Spring' was used as the common genetic background and the donor varieties were 'Thatcher', 'Hope', and 'Timstein'. In the Thatcher set only chromosome 2A changed any of the properties evaluated. Eleven Hope chromosomes produced some changes with major effects in baking attributed to 2B. Sixteen Timstein chromosomes resulted in altered flour properties with 3B and 6B being the most important.
Transfer of Blue Mold Resistance into F1 Tobacco Hybrids1
Authors: Dean C. E. , Heggestad H. E. , Grosso J. J.
Published: July 2010

Seventeen F1 hybrids resulting from crosses between tobacco (Nicotiana tabacum L.) breeding lines and varieties having different levels of blue mold (Peronospora tabacina Adam) resistance were evaluated. The parental lines were also evaluated to provide a basis for rating the hybrids. The resistance of the F1 hybrids and parental lines was determined both at the seedling stage in greenhouses and at a more mature growth stage in the field.

Seventy‐two percent of the F1 hybrids were intermediate between the parental lines in terms of resistance classification. Those outside the parental limits were always slightly more susceptible rather than more resistant than the parents.

Differences in the effectiveness of lines in imparting resistance in an F1 hybrid were demonstrated. These differences were postulated to be caused by a more complementary genetic constitution containing modifiers which interact favorably with the major blue mold resistance genes. 'Dixie Shade' was a more desirable parent than was 2238.

Blue mold resistance at an effective field level can be utilized in F1 hybrids provided that careful selection of parental lines for resistance and other characteristics is practiced. Hybrids from crosses of resistant and susceptible parents should have a level of resistance sufficient for average field conditions.
Variance Components for Irrigated Seed Flax (Linum usitatissimum L.) Yields Trials1
Authors: Beard Benjamine H. , Worker George F.
Published: July 2010

The variance components for varieties with years and locations were determined for irrigated seed flax yield tests. Estimated standard errors of a varietal mean for comparative purposes were calculated for different combinations of years and replications. Testing 4 years with 6 replications, or 5 years with 3 replications gave estimated standard errors of 1.8, a magnitude considered practical for these tests.