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Separate inheritance of mania and depression together with high rates of clinical overlap of mania with anxiety and substance use disorders provide a basis for re-examining the specificity of the prospective association of manic and depression episodes that is a hallmark of bipolar disorder. We analyzed information from 34 653 adults in Waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions, a longitudinal nationally representative survey of US adults interviewed 3 years apart. Psychiatric disorders were assessed by a structured interview. We used logistic regression analyses to estimate the strength of associations between Wave 1 manic episodes and Wave 2 depression, anxiety and substance use disorders controlling for background characteristics and lifetime Wave 1 disorders. Corresponding analyses examined associations between Wave 1 major depressive episode with manic episodes and other psychiatric disorders. In multivariable models, Wave 1 manic episodes significantly increased the odds of Wave 2 major depressive episodes (adjusted odds ratio (AOR): 1.7; 95% confidence interval: 1.3–2.2) and any anxiety disorder (AOR: 1.8; 1.4-2.2), although not of substance use disorders (AOR: 1.2; 0.9–1.5). Conversely, Wave 1 major depressive episodes significantly increased risk of Wave 2 manic episodes (AOR: 2.2; 1.7–2.9) and anxiety disorders (AOR: 1.7; 1.5–2.0), although not substance use disorders (AOR: 1.0; 0.9–1.2). Adults with manic episodes have an approximately equivalent relative risk of developing depression episodes and anxiety disorders. Greater research and clinical focus is warranted on connections between manic episodes and anxiety disorders.

Modulation Assisted Machining (MAM), based on controlled superimposition of low-frequency modulation to conventional machining, effects discrete chip formation and disrupts the severe contact condition at the tool-chip interface. The underlying theory of discrete chip formation and its implications are briefly described and illustrated. Benefits such as improved chip management and lubrication, reduction of tool wear, enhanced material removal, particulate manufacturing and surface texturing are highlighted using case studies. MAM represents a new paradigm for machining in that it deliberately employs ‘good vibrations’ to enhance machining performance and capability.

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The deformation field associated with chip formation in plane strain (2-D) machining has been simulated using the finite element method (FEM), with the objective of developing 2-D machining as an experimental technique for studying very large strain deformation phenomena. The principal machining parameters are the tool rake angle, cutting velocity and the friction at the toolchip interface while the deformation field parameters are strain, strain rate and temperature. The relation between rake angle and the shear strain in the deformation zone is studied for the low-speed cutting of lead. This correspondence is validated by comparison with measurements of the deformation parameters made by applying a Particle Image Velocimetry (PIV) technique to highspeed photographic image sequences of the deformation. It is shown that plastic strains in the range of 1-15 can be realized in a controlled manner by appropriate choice of the rake angle. The unique capabilities offered by 2-D machining for studying micro- and nano- mechanics of large strain deformation, and the creation of ultra-fine grained materials are highlighted in the context of these results.

ABSTRACTThe need to provide teams with clear, concise goals is prevalent in the team literature. Advancing this idea one step further involves the need for team members and the organization to have a shared understanding of what is required. Data collected from team leaders and members are explored to assess the direct relationship between team goals and team performance, the level of agreement between team leaders and members, and the consequences of divergent opinions.Team goals are positively related to team performance on business goal achievement, schedule performance, and internal team processes. Team leaders and members were found to disagree on the level of internal team processes used; however, this divergence had no impact on team performance. Further, team members were found to disagree only when team goals were reported to be at lower levels.

Dry matter yields and forage quality of plant components (leaf, stalk, and ear) through maturity could vary among corn (Zea maysL.) hybrids. These potential differences could affect total forage quality yield and the hybrid choice for corn silage use. To compare plant composition, total plant dry matter, and forage quality among corn hybrids from flowering to physiological maturity, we studied leaf, stalk, and ear dry matter production and forage quality of three corn hybrids with maturity. Three corn hybrids, ‘Nebr. 611’, ‘Nebr. 612’, and ‘Nebr. 712’, were grown under field conditions with optimum agronomic conditions on a Sharpsburg silty clay loam (Typic Argiudolls) soil and harvested at six kernel development stages within 9 weeks following flowering during 1973 and 1974. All forage was separated for leaf, stalk, and ear dry matter production, and analyzed for crude protein, and in vitro dry matter disappearance (IVDMD). Total plant dry matter production increased at most harvests both years for all hybrids. Hybrid 712 yielded significantly more forage than 611 and 612 for most harvests. Stalk dry matter production declined over the harvests both years while leaf production increased during 1973. Leaf production remained the same over the harvests in 1974 for hybrids 611 and 612. Ear dry matter production increased at each harvest for all hybrids both years. Leaf crude protein was twice as large as stalk crude protein and declined over all harvests for the leaf component. Percent crude protein of ears declined through the first three harvests only. No hybrid differences were detected in percent crude protein of the three yield components. Leaf IVDMD was higher than that of stalk IVDMD. Rate of IVDMD decline was greater in stalks than leaves. Leaf IVDMD was consistently higher in 712 than 611 or 612. Little change occurred in ear IVDMD over the six harvests, however, the values were significantly greater in 1974 than 1973. The greatest plant protein and IVDMD yield occurred at the last harvest, physiological maturity, both years for all hybrids. Variation was detected among hybrids for total plant dry matter and plant component yields but less variation was detected among hybrids in forage quality for each plant component.

Twenty cycles of divergent mass selection for seed size have been completed in the corn (Zea maysL.) cv. Krug yellow dent. A 2‐yr field study was conducted to evaluate direct and indirect responses to seed‐size selection and to observe whether significant changes in yield occur with selection for seed size. A third objective was to investigate the immediate effect of male gametes (pollen) on seed size and to observe whether such effects exhibit heterosis. The study was conducted in the breeding nursery in Lincoln, NE, where the soil type is Kennebec silt loam (Cumulic Hapludolls). Selection was highly effective for both large and small seed size. Selection for small seeds resulted in a decrease in kernel weight of 7.21 g/1000 kernels per cycle while selection for large seeds resulted in an increase in kernel weight of 4.68 g/1000 kernels per cycle. The effect of male gametes on seed size was found to be dependent on the source of the pollen. After 20 cycles, pollen from the large seed‐size population (L) increased seed size by 0.12 g/kernel when used to pollinate plants from the small seed‐size population (S). Pollen from the S population reduced seed size by 0.15 g/kernel when used on plants in the L population. Such large effects were not expected although some effects had been previously demonstrated in dent corn. Even though selection for small seeds resulted in a significant increase in the number of seed harvested per square meter, yield was significantly reduced. Selection for large seeds had no significant effect on yield.

Two cycles of S1per se selection have been completed in each of three corn (Zea maysL.) populations: Nebraska B Synthetic (NBS), Nebraska Stiff Stalk Synthetic (NSS), and improved Nebraska Krug variety (NKS). In addition, two cycles of reciprocal full‐sib recurrent selection (RFS) have been completed between NBS and NSS and between NBS and NKS. Each selection scheme was replicated three times. Selection was based on an index (resulting in a calculated value of yield on standing plants) and on yield trials generally grown at 51,666 plants/ha. Response at 68,888 and 17,222 plants/ha (called here indirect density response) is reported in this study. Each replicate of each selection procedure was grown as an S1, random mating (RM), or variety cross population. Index values of cycle 2 (C2.) were increased 20% or more over C0in tests of bulked S1populations selected by S1per se performance while response to RFS selection varied from an increase of 9% in C2of NKS to a negative response of −10% in NBS. Significant selection ✕ plant populaion density effects were found only in the random mating test of the NKS population. Response to S1per se selection was significantly greater than response to RFS selection in the NBS random mating population, but response to the two methods did not differ in NSS or NKS grown as random mating populations. Index means of variety crosses of C2were approximately 12% above C0variety crosses and there were no differences between selection methods. The evaluation of selection response indicated that in the early cycles of selection, response to selection at one plant density will be unchanged when selection products are grown at other plant densities. Response to S1per se selection was greater than RFS selection response in bulk S1and RM evaluations, but the RFS and S1per se methods resulted in equal improvement of variety cross performance.

The effect of plant age and inoculum concentration on disease reactions in corn (Zea maysL.) was determined following inoculation with Corynebacterium nebraskenseSchuster, Hoff, Mandel, and Lazar, the causal organism of the leaf freckles and walt of corn. Resistant and susceptible corn materials were simultaneously inoculated at four different age groups and at four inoculum concentrations for each group. Plant age or maturity played a vital role in differentiating resistant from susceptible lines when the syringe injection technique was used. Susceptible materials were not greatly influenced by plant age. On resistant lines, however, the disease ratings were strongly influenced by plant age. In resistant materials, infection decreased with increased plant maturity, but with the susceptible genotype the greatest infection occurred in plants inoculated at tasseling. Inoculum concentration was a critical factor only in young plants. However, optimum concentration was difficult to define because the results were variable. In tasseling plants, higher concentrations were tolerated without affecting disease reaction.

Five cycles of S1per se (S1) and reciprocal full‐sib (RFS) selection were compared for the improvement of three maize (zea maysL.) populations and two population crosses. The replicated structure of the selection experiments allowed direct comparisons of selection methods together with measures of genetic drift. The selection criterion used was a multiplicative index involving yield, moisture, upright plants, and undropped ears and therefore the experiment measures the value of this type of index in selection studies. Populations and population crosses evaluated were Nebraska B. Synthetic (NBS), Nebraska Stiff Stalk Synthetic (NSS), Nebraska Krug open pollinated variety (NKS), NBS ✕ NSS, and NBS ✕ NKS. Improvement was measured in random mated, bulked inbred (S1) populations, and the population crosses. Both selection procedures were performed in three replicates. The entries for the evaluation study were derived from Cycle 0 and recombined replicate populations from Cycles 3 and 5. The evaluation trials were grown in 1985 and 1986 at Lincoln, NE. The S1selection increased index values in the bulked inbred populations by 5.8% per cycle when averaged over populations. The RFS selection increased index values of inbred populations by 3.4% per cycle. Both methods were equally effective in improving index values of the random mated populations with average responses of 2.0% for S1and 1.8% for RFS selection per cycle. The average index response in the population crosses was 3.6 and 2.9% per cycle for RFS and S1selection, respectively. Genetic drift was observed to cause significant differences among the replicate populations for index and its components.

Our objectives were to study genetic variation and realized response to selection for oil quantity and quality. Information on genetic variation in broad based corn (Zeam maysL.) population is needed for decisions about breeding methods to be used for oil enhancement in such populations. Quality measures are important for determining correlated responses to selection for high oil. Previous estimates have generally been based on generation means of narrow based populations. Genetic parameters of oil quantity and composition were estimated by analysis of 89 interpopulation full‐sib families and their S1line parents from ‘Nebraska B’ and ‘Nebraska Krugp’ populations. Percent oil was determined using Nuclear Magnetic Resonance spectroscopy. Fatty acid proportions were determined using gas‐liquid chromatographic analysis. Results revealed that significant genetic variation exists for both fatty acid composition and percent oil. Negative genetic correlation(r= −0.96) was found between oleic and linoleic acids, as expected. Percent oil was positively correlated with oleic (r= 0.51) but negatively correlated with linoleic (r= −0.48), suggesting a potential correlated response from selection of lowered quality with increased quantity of oil. A cycle of selection was completed and response to selection measured for three separate selection criteria (linoleic acid, total unsaturated fatty acids, and percent oil). Response to selection indicated that significant increases were obtained for each criterion. Both S1line per se and reciprocal full‐sib selection were effective, however linoleic acid was increased significantly more by the S1per se method. Our data indicate that oil quantity and quality can be changed by recurrent selection. It also appears that by careful monitoring of fatty acid proportions, oil quantity can be increased without lowering oil quality, at least for a few cycles.

Iron deficiency chlorosis (FeDC) in various degrees affects nearly 500,000 ha of corn (Zea mays L.) in Nebraska, primarily in the river valleys, but also on eroded uplands. Corn hybrids produced from 27 public released and 45 experimental inbreds were grown on a Cozad silt loam, saline-sodic (Typic Haplustolls). This soil is slightly calcareous with average pH of 8.3, organic matter 1.8%, DTPA-iron 2.59 ppm, SAR 1.75, and electrical conductivity (EC) of 1.97 in the top 28 cm. Salinity and sodium increase in the next 28 cm with pH at 8.6, SAR 3.44, and EC 2.12. Under these conditions, corn grain yields ranged from 0 to nearly 7600 kg/ha. Yields of the most tolerant hybrids were still only 60-65% of those hybrids grown on a Cozad silt loam with lower salinity and sodium. Susceptibility to FeDC is very genotype specific with the most extreme case being MO17 by N192 yielding 6400 kg/ha, while MO17 by N195 gave 0 yield. Average yield of the six hybrids made with N139 as a parent was 398 kg/ha. Several other inbreds gave low yield in all hybrids tested. Three hybrids with A634 as a parent averaged 5985 and three with N193 averaged 6110 kg/ha. The cross A634 by N193 produced 7345 kg/ha. The highest yielding hybrid resulted from a cross of two experimental inbreds selected for tolerance to the saline-sodic conditions. The data from several parent line combinations suggest that at least two major genes are involved in these levels of tolerance. Results show the genetic relationship of tolerance in corn to saline-sodic soils. Enough inbred line differences have now been identified to permit more definitive inheritance studies.

A maize inbred line (Purple 3036-1) with tolerance to nigh-pH soils was crossed with susceptible homozygous translocation stocks that marked all chromosome arms, except the short arms of 3 and 7 and the long arm or 10. F2's and test crosses to the appropriate translocation stocks were used in the analysis.A randomized complete block design with eight replications was used to evaluate the height difference between paired rows grown from normal and mutant seeds. Six replications were grown on land that had formerly been a creek bed and ranged in pH from 8.2 to 9.1 at 0 to 20 cm. Two replications were grown in a nearby field with a pH of 7.9 at 0 to 20 cm as a control. The treatment design was a split-split-plot with the translocation being the whole plot, the F2 and test cross involving the same translocation as the subplot, and the normal and mutant (sugary or waxy) rows as the sub-subplot.The results were evaluated using a t-test that combined data from both the F2 and the test cross of a particular translocation. Genes for tolerance to lime-induced stunting were located on the short arms of chromosomes 2, 4, and 10 and on the long arms of 3, 6, and 8. The largest differences were demonstrated by progenies testing the long arms of chromosomes 3 and 8.

The use of several S1 individuals to represent an S0 individual permits the use of a Design II mating scheme for plants with only one pistillate flower per plant. Estimates of additive (VA) and dominance (VD) variance from this mating scheme will be biased upwards, when a small number (10) of individuals of each S1 line are used. This bias can be computed, and the additive and dominance estimates can be corrected. Of particular interest is the observation that the additive genetic variance contributes to bias in estimates of VD. When S0 plants are non inbred and their selfedprogeny (S1 lines) are used to represent them in developing families for use in the Design II, $$\hat VA = \hat VA\left( {1 + 1/2m_1 } \right){\text{ and V}}_{\text{D}} {\text{ = V}}_{\text{D}} \left( {{\text{1 + }}\frac{{\text{5}}}{{{\text{4m}}_{\text{2}} }}} \right) + \left( {\frac{1}{{m_2 }} - \frac{1}{{m_1 }}} \right)V_A $$ where m1 is the number of individuals used to represent an S1 line in developing half sib-families and m2 is the number of individuals used to represent the S1 line in making up full sib-families. For example, in a 3×3 Design II, with about 10 individuals used to represent each S1 line in each cross, m2 = 10 and m1 = 30. When m1 = m2 = 1, $$\hat V_A = \left( {1 + 1/2} \right)V_A = \left( {1 + F} \right)V_A $$ and $$\hat V_D = V_D + \frac{5}{4}V_D = \left( {1 + F} \right)^2 V_D $$

Four experimental single-cross hybrids were evaluated for intergenotypic competition in a split-plot design with 7 replicates and a stand density of 51,700 plants/hectar in 1970, 1971 and 1972 at Lincoln, Nebraska. The arrangement of rows used in this study allowed the measurement of effects of different levels of competition on the traits grain yield, plant height and a selection index. There were some definite inter-genotypic competitive effects for all three traits among the pairs of hybrids studied. Variation in types of intergenotypic interaction was found.

Variation in recombination rate is important to plant breeders since a major objective is to obtain favorable recombinants of linked genes. The ability to increase recombination (R) in circumstances in which favorable and unvavorable genes are linked (Corn Belt x exotic populations) and to decrease recombination when many favorable genes are linked (narrow-based, elite populations) would be of immense value. However, the concept of variation in recombination frequencies between linked genes has received limited attention despite its implications in breeding and genetic linkage studies. Molecular techniques have allowed better estimations of this variation. In this study, attempts were made to characterize: (1) the R values in the Pgm1-Adh1 and Adh1-Phi1 adjacent regions of chromosome 1 and the Idh2-Mdh2 region of chromosome 6 in F2 families of three maize (Zea mays L.) populations; (2) the environmental effect on R values of F2s from two populations. One population, NSO, was a Corn Belt synthetic, and the other two populations, CBMEX3 and CBCAR5, were composites from crosses between Corn Belt and exotic germ-plams.

Design II progenies from an exotic population of corn (Zea mays L.) were evaluated in a randomized incomplete block design with two replications at two plant-population densities (17,222 plants/ha and 68,888 plants/ha) in 1970 and 1971, at Lincoln, Nebraska. Five traits were studied, i.e., grain weight, number of ears, days to flower, plant height, and ear height.

Progenies of a Design II [Comstock and Robinson (1948)] using random S1 lines from an exotic population of corn (Zea mays L.) were evaluated in a randomized incomplete block design with two replications at two plant-population densities (1 7,222 plants/ha and 68,888 plants/ha) in 1970 and 1971, at Lincoln, Nebraska. Five traits were studied i.e. grain weight, number of ears, days to flower, plant height and ear height.

The purpose of this study was to obtain information on average gene frequency in two corn (Zea maysL.) populations. A design I mating system consisting of 100 males crossed to three females was developed in each of two open pollinated cultivars, ‘Golden Jewel’ and ‘Osterland's Yellow Dent.’ In addition, the male plants of the design I in each cultivar were selfed and crossed to females of the other cultivar. The intra‐population progenies, the inter‐population progenies, and S1progenies from each cultivar were evaluated at two locations for yield, ear moisture, stalk lodging, and ear height. Days to flower was evaluated at one location only. Ratios of estimated genetic components of variance and covariance were compared with corresponding theoretical ratios computed for various gene frequencies and levels of dominance. From these comparisons, approximate ranges of the gene frequencies in the two cultivars and relative magnitudes of gene frequencies were obtained. The average frequency of favorable genes for yield appeared to be greater than 0.5 in both cultivars. There was some indication that the frequencies of favorable genes were lower for the other traits than those for yield. The ratios of variances among S1progenies and covariance of S1progenies with intra and inter‐cultivar crosses did not appear to add new information on gene frequencies, but supported the information gained from the comparison of the ratio of additive to dominance variance, the ratio of intra to inter‐cultivar variance, and the ratio of covariance of intra‐cultivar crosses with inter‐cultivar crosses. The average gene frequency for yield appeared to be higher in Osterland's Yellow Dent than in Golden Jewel.

Maize (Zea mays L.) germplasm with good tolerance to high pH soil has been noted. This tolerance was found in agronomically poor germplasm. Efforts are underway to determine the genetics involved in the tolerance and its transfer to more elite lines. The germplasm was evaluated in 1985 under pH environments ranging from 8.0 to 9.6 at the 0-20 cm depth and 8.3 to 10.0 at the 20-40 depth.

Thucydides (iv. 36) describes the last phase of the long contest which led to the surrender of the 292 surviving Spartans on Sphacteria.They had gradually retired to the summit of the hill at the north end of the island,—an altitude of something under 500 feet, and were making their last stand in the neighbourhood of the pa?a??? ?p?µamentioned by Thucydides, which had once defended this summit, and of which small fragments are yet to be seen. These fragments are still there, for since prehistoric times this practically waterless island has probably never had inhabitants except a few nomad goatherds.The ground,—working round west, north, east, south,—is as follows, and, the photographs reproduced will help to make it clear (Fig. 1, and Plan) To the S.W. is the long slope up which the Spartans had been slowly retiring from their camp on the low level in the centre of the island. To the west the hill falls, not very steeply, to a saddle; and from this and all sides except (as they thought) the east, the Spartans were exposed to attack; then comes a shoulder before the ground slopes away westward to the open sea.

Luminescence in irradiated silicon has been used to determine the thermal stability of the defects responsible for the recombination. It was found that the defect responsible for the zero-phonon line at 0.97 eV has an annealing behavior similar to that of the divacancy and the zero-phonon line at 0.79 eV anneals in a manner similar to the G-15 or K-center. Annealing at temperatures up to 500 °C generates other defects whose luminescence is distinct from that seen previously. Addition of lithium to the material produces defects with new characteristic luminescence. Of particular importance is a defect with a level at Ev - 1.045 eV.

Luminescence in irradiated silicon consists of a spectral group between 0.80 eV and 1.0 eV which seems to be independent of impurities while a lower energy group between 0.60 eV and 0.80 eV is seen only in pulled crystals. The small halfwidth and temperature dependence of the sharp zero-phonon lines observed in these spectra indicates that the luminescence arises from a bound-to-bound transition. A model is proposed for the transition mechanism. Stress data taken on the 0.79 eV zero-phonon line in pulled crystals can be fit by either a tetragonal [100] defect symmetry or by conduction band splitting effects. It is suggested that the 0.79 eV zero-phonon line and the 0.60 eV to 0.80 eV spectral group arise from the EPR G-15 center. Stress data on a zero-phonon line at 0.97 eV associated with the 0.80 eV to 1.0 eV spectral group can be explained by a trigonal [111] defect. The divacancy is tentatively suggested as responsible for this luminescence spectra.

This is a two-part paper, which stresses the materials science approach to understanding dust erosion mechanisms. The first part is an experimental phase, studying the effects upon solid-particle erosion, of such material and environmental variables as target alloy composition and heat-treat condition; dust particle velocity, size, concentration, velocity, and kinetic energy; carrier-gas true temperature and impingement angle. All test variables and their limits were chosen to simulate the range of engineering conditions and erosive environments encountered in helicopter turbine service. Actual erosion data are compared with erosion levels predicted by existing theories on particulate erosion. The second part is a diagnostic phase, programmed to detect and study visible phenomena associated with the erosion processes, using high-magnification electron microscopy. Phenomenological evidence obtained from the erosion surfaces and erosion products are used to define probable physical models of the erosion mechanisms.

Two populations of corn (Zea maysL.) improved by nine cycles of mass selection for yield and the unselected parent variety, ‘Hays Golden,’ were evaluated in 1969 and 1970 using random S1lines and their testcrosses to related and unrelated single‐cross testers. One selected population received thermal neutron seed treatment prior to the first and third selection cycles. S1lines of the selected populations, per seand in testcrosses, demonstrated significant superiority in mean yield over lines of the parent variety in each year. Like progenies of the two selected populations produced similar yields. Selection evidently eliminated radiation‐induced deleterious mutants from the “irradiated” population while increasing frequencies of favorable yield genes common to both selected populations. This apparently produced similar germ plasm reservoirs much more suitable for the extraction of superior inbred lines than the parent variety. Indications are that selection also reduced genetic variability in yield and combining ability. Prolificacy resulting from selection for yield was evident in S1lines but not in the testcrosses. Since inbreeding did not reduce prolificacy in the selected populations, results are interpreted to mean that tester genes masked recessive genes which induce prolific potential when homozygous. All phenotypic correlations between S1and testcross yields were too low to be of much predictive value; but in general, lines of the selected populations exhibited the least correlation with their testcrosses. Genetic correlations were somewhat higher, indicating sizeable environmental fluctuations in individual experiments. We postulate that non‐prolific testers by inhibiting prolificacy in turn limit the expression of genes controlling yield in these populations. Use of a prolific tester might have provided greater yield differentiation, more precise estimates of line genotypes and higher correlations between S1and testcross progenies.

In recent years automotive engine emissions have become subject to stringent Federal legislation. The most severe of these regulations pertains to the 1976 Emission Standards as defined by the Advanced Automotive Power Systems (AAPS) Division of the Environmental Protection Agency (EPA). A unique combustor concept has been developed by Solar which has demonstrated the feasibility of meeting these emission requirements. The integrated emissions of a typical regenerative gas turbine engine employing this combustor type were each below one half of the levels specified by the Federal 1976 Standards, when tested over a simulated federal driving cycle. The success of the feasibility tests for this combustor concept has lead to more fundamental studies and the planned development of a prototype combustor for demonstration on the EPA-AAPS baseline gas turbine engine. The prototype combustor for the baseline engine is described together with its variable area port mechanisms, which has been demonstrated as necessary for emission control.

Full and half-sib reciprocal recurrent selection (RRS) were compared algebraically and with computer simulation. The relative performance of the two schemes depended on the selection intensity and the environmental variance. Full-sib RRS was favoured at less intense selection and when the environmental variance was large relative to the total genetic variation. As selection intensity increased its advantage declined. Full-sib RRS enables a breeder to combine the efficient development of new hybrids with population improvement and should be a valuable technique in plant breeding.

A condensed form of full‐sib family recurrent selection in maize (Zea maysL.) is described that requires two growing seasons per cycle. Results of four cycles of selection in the open‐pollinated variety Krug in Nebraskare reported. The selection criterion was a multiplicative selection index composed of grain yield adjusted by proportion of dry matter ✕ proportion of upright plants ✕ proportion of plants without dropped ears. Yield increased 2.9 quintals/ha/cycle (4.7%) whereas the index increased 2.8 quintals/ha/cycle (5.8%). Proportions of dry matter, upright plants, and plants without dropped ears showed non‐significant but positive changes.

Full‐sib selection is one method of intrapopulation improvement used in maize (Zea maysL.). This study was conducted to evaluate the progress from 10 cycles of full‐sib recurrent selection in the Nebraska Krug open‐pollinated maize population. A 2‐yr full‐sib selection cycle was applied to the Krug population beginning in 1966. The selection criterion was a multiplicative selection index consisting of yield (adjusted to 155 g kg−lmoisture), proportion of standing plants, and proportion of plants without dropped ears. Based on field evaluations across nine seasons, the selection index increased 0.17 Mg ha−lcycle−1(4.4% cycle−1), yield increased 0.07 Mg ha−lcycle−l(1.2% cycle−l), the proportion of standing plants increased 2.8% cycle−l, and the proportion of plants without dropped ears increased 0.1% cycle−l. Grain moisture at harvest decreased 3.0 g kg−lcycle−1(0.3% cycle−1). Changes in plant traits other than those involved in the selection index were also measured. The multiplicative selection index was successful in increasing the yield on standing plants when applied to a full‐sib breeding system. Data indicate that yield on standing plants has continued to increase through the tenth cycle of selection.

The development of basic breeding populations that are adapted to a wide area and have at least some resistance to crop hazards in a region is important to breeders. A program designed to develop such a population of maize (Zea maysL.) for the northern Cornbelt is described. Six breeders in the area contributed germplasm samples (convergence) which were intercrossed. Samples of the resulting population were sent to each collaborator (divergence) who practiced mass selection for healthy, productive plants. In subsequent years, harvested samples (balanced composites) sent to Wisconsin (the convergent phase) were subdivided and redistributed (divergence) in such a way that seed for each location did not include seed harvested from that location the previous year. Results from the first four cycles of selection were evaluated in performance trials at all locations over a 2‐year period. Significant increases in productivity (gram yield) and reduction in grain moisture at harvest were obtained. Evidence of increased stability was noted over the four cycles of selection.

A modified ear‐to‐row selection program in corn Zea mayaL.) was initiated in Nebraska by Dr. J. H. Lonnquist in 1961. This paper describes results through the 10th cycle. Grain yields have continued to increase through the 10th cycle, but there is some evidence of curvilinearity. Part of this might be the result of a change in the selection criterion after the seventh cycle. At that time we began using a selection index that included lodging and dropped ears in addition to yield. The authors feel that it is unlikely that the selection study is plateaulng and therefore feel that linear regression estimates of gain are still appropriate. Gains in yield reported here from such an estimate are at the rate of 5.26% per cycle. Correlated responses in lodging, moisture at harvest, ear height, and number of ears per plant are discussed. Yield gains, though not very large, are still larger than those from mass selection in the same cultivar.