bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interrelationships Among Yield Stability and Yield Components in Early Maize1
Authors: Cross H. Z. 
Published: July 2010

A very early and an early set of made (Zea mays L.) hybrids were grown in nine and 11 environments, respectively, to evaluate the relationships between yield stability, as estimated by regression analysis, and various agronomic traits. Results indicated that general stability, as estimated by the regression coefficient, was associated with yield, kernel depth, and number of kernel rows per ear. Specific stability, estimated by the mean squares of deviations from regression, was associated with ears per plant. Within the later maturing diallel set, hybrids with more ears per plant had lower deviation mean squares, while the opposite was found within the earlier diallel set.Correlations among general combining ability (GCA) effects for various traits were computed to evaluate their associations within each of the two populations. Correlations among GCA effects were in general agreement with the phenotypic correlations. Generally, inbreds with high GCA effects for kernel depth and kernel rows per ear had high GCA effects for yield. Correlations between GCA effects for kernel depth and kernel rows per ear were 0.62 and 0.64 for the late and early maturing diallels, respectively.The absence of environmental interactions with GCA or specific combining ability (SCA) effects for kernel depth indicated selection for this trait may be important for development of high yielding hybrids from these inbreds or populations derived from these inbreds. The failure to detect SCA effects or interaction with environment for ears per plant indicates a selection scheme such as mass selection should be effective in changing this trait within derived populations, but the results indicate prolificacy may be undesirable within the earlier hybrids.
Spatial Orientation of Wheat Leaves1
Authors: Ledent J. F. , Moss Dale N. 
Published: July 2010

A model is presented for characterizing and summarizing leaf spatial orientation in wheat (Triticum aestivum L. em Thell) canopies. The model assumes a random azimuth we found to be valid for wheat. The inputs to the model are based on measurements of the angle to the horizontal of the basal and distal segments of each leaf midrib and a visual classification of the leaf into twist categories based on the number of twists along the leaf. Each leaf is considered to be made up of small, sequential, planar segments, and the relative distribution of area along the length of the midrib must be determined on a few leaves to fit the model to a particular genotype. With these relatively few and simple measurements to “calibrate” each genotype and two measurements of angle on each leaf, the spatial orientation of the entire leaf surface can be determined.The spatial orientation can be expressed in various ways. The customary cumulative angle distribution for all the leaf tissue can be obtained from the model. Other statistics have proven useful in our studies. The mean basal angle, MBA, (the mean for all leaves of the angle between the plane of the base of the midrib and the horizon) is useful for following changes in time of the angular display of individual leaves or of leaves at a particular insertion level. The planar equivalent angle, PEA, (the angle equivalent to that which all leaves would have if they were rigid planes and set at an angle which would give the same horizontal projection as that found in the canopy) is useful to express the leaf angle of a canopy as a single number.In addition to the measurements listed above, the relative distribution of area among leaf insertion levels and the leaf area index are required to utilize the orientation model in photosynthetic simulation.The orientation of leaves of the wheat cultivar ‘Era’ and an upright‐leaved mutant of Era were compared in controlled environments and in field plantings. Canopies became increasingly more planophile with time because leaves drooped as they aged. Leaf drooping was characterized by a change in the angle of the base of the leaf blade with the leaf sheath.
Basis of Heterosis in the Differentiating Sorghum Panicle1
Authors: Blum A. 
Published: July 2010

Heterosis in grain sorghum (Sorghum bicolor L. (Moench)) yield has been previously traced to heterosis in the number of grains per basal branch in the panicle. A comparative quantitative morphogenetical study of the differentiating panicle was performed to explore the origin of this heterotic effect. Field grown plants of RS 610 hybrid and its two parental lines (B‐Combine Kafir 60 and Tx 7078) were dissected and studied microscopically.Heterosis (advantage of the hybrid over both parental lines) was identified in faster formation of primary and secondary panicle branches; faster panicle growth rate and larger primary basal branch primordia. The hybrid did not differ from the parental lines in the number of branch whorls per panicle, growth rate of basal primary branches, and the length of time period between spikelet and floret initiation.Heterosis in the number of grains per basal primary branch was traced to two major factors: (1) a larger reproductive apex that allowed development of larger basal branch primordia, and (2) a 4‐day time‐lapse between termination of the acropetal formation of branches and the onset of the basipetal formation of spikelets. This time‐lapse was utilized in the hybrid for the increase in basal branch size prior to spikelet initiation.
Inbreeding Depression in Maize by Selfing and Full‐sibbing1
Authors: Good R.L. , Hallauer Arnel R. 
Published: July 2010

Three series of unselected lines from ‘Iowa Stiff Stalk Synthetic’ (BSSSCO) were developed by three methods inbreeding: selfing, ful‐sibbing, and full‐sibbing followed by selfing. Data were collected for 12 traits in nine environments to determine: 1) the rate of inbreeding depression by selfing, full‐sibbing, and full‐sibbing and selfing; 2) the differences among means of lines developed by the three methods of inbreeding at comparable levels of homozygosity; and 3) the phenotypic correlation between the traits with the change in homozygosity by inbreeding.Rates of inbreeding depression were significantly different among the three methods of inbreeding for plant height, cob diameter, yield, kernel weight, stand, and barrenness. In most instances the differences were small. Predicted yields by the linear regression model for F = 1.0 were 23.2, 24.6, and 23.9 q/ha for the selfed, full‐sib, and full‐sib and selfed series of lines, respectively, whereas with F = 0, yield was 69.7 q/ha. Rate of inbreeding depression for yield by selfing was b1 = ‐‐46.53 q/ha and by full‐sibbing, bL = ‐‐45.11 q/ha. At comparable levels of homozygosity, means of the lines developed by selfing and full‐sibbing were not significantly different except for yield at 99% homozygosity. All correlations of traits with percentageo f homozygosityw ere very high. Linear regression of yield on percentage of homozygosity for 22 levels of homozygosity is BSSSCO accounted for 99.1% of the total variation.
Variability, Combining Ability, and Interrelationships of Anther Length, Anther Extrusion, Glume Tenacity, and Shattering in Spring Wheat1
Authors: Atashi‐Rang G. , Lucken K. A. 
Published: July 2010

Thirty spring wheat (Triticum aestivum L., T. aestivum with T. timopheevi Zhuk. cytoplasm, and T. turgidum L. var. durum) cultivars and lines, both normal (B‐line) and restorer (R.line) genotypes, were grown at Fargo, N.Dak. in 1968 to assess variability and intercharacter associations for four floral traits: anther length, anther extrusion, glume tenacity, and shattering. In a second experiment the following year, 36 B‐line/R‐line (B/R) hybrids and their six B‐line and six R‐line parents were grown to further evaluate variability and intercharacter associations and to obtain estimates of the relative magnitude of general and specific combining ability effects for anther length, anther extrusion, and glume tenacity.Substantial variation among genotypes was found for each of the four traits in both experiments. Significant differences for both general and specific combining ability effects of parents were obtained for anther length, anther extrusion, and glume tenacity. The general combining ability to specific combining ability variance component ratio was approximately 5:1 for anther length, 1:1 for anther extrusion, and 8:1 for glume tenacity. Narrowsense heritabilities on a per spike basis were 0.61, 0.19, and 0.54 for the three respective traits. Correlations between F1's and each parent or mid‐parent were relatively high for anther length and glume tenacity but low or nonsignificant for anther extrusion. Selection to alter anther length and glume tenacity should be effective in this group of wheats. Selection in stress environments was suggested as a possible means of improving and stabilizing anther extrusion.All intercharacter associations were nonsignificant except for a low positive correlation between anther extrusion and shattering, and a low negative correlation between glume tenacity and shattering, both in the second experiment. Thus, adverse associations with glume tenacity or shattering should not seriously impede progress in improving anther length and anther extrusion.
Sterility Induced in Barley by a Synthetic Pyridone1
Authors: Hockett E. A. , Feltner K. C. 
Published: July 2010

A chemical gametocide capable of inhibiting pollen production but not affecting female fertility, would be very useful in the production of hybrid barley (Hordeum vulgate L.). In this study, ‘Betzes’ and two ‘Unitan’ two and six row isogenics were sprayed with 0, 1, 2, and 4 kg/ha of sodium 1‐(p‐chlorophenyl)‐l,2‐dihydro‐4,6 dimethyl‐ 2 oxonicotinate (RH‐531) at the five and six‐leaf stages in an attempt to induce male sterility. Seed set was lowest on plants treated at the 4 kg rate and was as follows: Betzes, 18% at five‐leaf stage; Unitan two‐row 33% at six‐leaf stage; and Unitan six‐row 29% at six‐leaf stage. Four kilograms of RH‐531 caused 40% female sterility. Female sterility was greatest when plants were treated at the six‐leaf stage and Unitan six‐row had the most female sterility at that stage.As rates of RH‐531 were increased, yield, plant height, flowers per spike, lodging, kernel size, and spike length of treated plots decreased. Yield and grain protein were negatively correlated (r = —0.90**), but grain protein/ ha was less in the 4 kg/ha plots because of lower yield. Spraying at the six‐leaf stage reduced yield and plant height more than spraying at the five‐leaf stage. Treatment affected the growth characteristics of Unitan six‐row less than it did the other two cultivars. The number of flowers per spike was reduced less at the six than at the five‐leaf treatment stage in the Unitan isollnes.RH‐531 did not produce sufficient male sterility to be useful in hybrid barley production, and adverse side effects such as reduced female fertility and stunted plants were drastic.
Relationship Between Alpha Acids, Beta Acids, and Lupulin Content of Hops1
Authors: Likens S. T. , Nickerson G. B. , Haunold A. , Zimmermann C. E. 
Published: July 2010

The sum of (α+β) acids in lupulin glands of 112 female and 24 male genotypes of hop (Humulus lupulus L.) averaged 73 ± 6% by weight. Alpha‐ and beta‐acid content in glands from male or female hops was inversely correlated (r = −0.78 for females; −0.85 for males). A significant change in the a‐acid content of lupulin was associated with a similar change of β‐acid content in the opposite direction.The α‐acid content of hop cones was related to the quantity and quality of lupulin in the cones. The lupulin quantity was proportional to the sum of (α+β). Lupulin quality was related to the ratio of α‐ and β‐acids (α/β).Six test crosses were made with parents having high or low α/β values, respectively. The average α/β value for progenies from each cross was nearly identical to the parental midpoint. Data presented in this paper led to formulation of a new working hypothesis for the relationship between hop acids and lupulin content. Lupulin analysis is simple, and a modest laboratory can screen several hundred genotypes each season.
Diallel Analyses of Grain Yield, Percent Protein, and Protein Yield in Grain Sorghum1
Authors: Wilson N. D. , Weibel D. E. , McNew R. W. 
Published: July 2010

A six‐parent diallel cross, including reciprocals, of grain sorghum [Sorghum bicalor (L.) Moench] was analyzed for grain yield, percent protein, and protein yield. Highly significant differences were observed among parents and F1 hybrids for each trait. Reciprocal differences were not significant, but a partial failure of assumptions for the Jinks‐Hayman analysis was noted for all traits.Differences among the parents indicated an additive component of genetic variation for all traits. The estimates for non‐additive components suggested that dominance was important for all traits. The degree of dominance was estimated to be in the overdominance range, particularly for the yield traits. Dominance was in the direction of higher yields and lower percent protein. The positive and negative alleles were estimated to be equally frequent for yield; or percent protein, the negative alleles were estimated to be more frequent. These results suggest that improvement of percent protein requires selection for recessive alleles that have a low frequency; improvement of yield requires a method to cope with overdominance.Highly significant GCA and SCA effects were observed for all traits. A comparison of their relative magnitudes indicated SCA effects were much more important than GCA. Specified comparisons among the parents were made for GCA and among the parents and hybrids for SCA.
Evaluation of the Pure‐line Family Method for Cultivar Development1
Authors: Ivers D. R. , Fehr W. R. 
Published: July 2010

The pure‐line family method (PLF) has been proposed as a means of developing high yielding cultivars. The method consists of harvesting individual F2 plants from a population and selling the bulk progeny of each plant (family) to a desired level of homozygosity. individual plant (pure line) is harvested from each family, and yield tested in replicated trials. If a line has superior performance, additional plants from the F2 family are evaluated as potential cultivars.Two soybean [Glycine max (L.) Merr.] populations were used to compare the PLF method with three alternative methods used by soybean breeders, early‐generation testing of bulk progeny from F2 plants (BF), pedigree selection (PS), and single‐seed descent (SSD). derived lines developed by each method were compared for yield during 2 years. The BF method was superior to PLF for identifying the top F2 families, but the number of superior F5 lines selected was similar. The PLF method produced a greater number of superior pure lines than did PS or SSD. Yield of the top line was not different for the four methods.The choice between PLF and BF would depend on the resources available and the breeding objective. The PLF method generally would be a faster method for cultivar development than BF, but BF would be preferred when recurrent selection by early‐generatlon testing was feasible for improving a character. Cultivar development with PLF would be faster than with PS when winter facilities were available for generation advance. The PLF method may provide a larger number of superior F5 lines than SSD; however, it would sample less genetic variability and require more years, land, labor, and record keeping than SSD.
Photoperiod and Critical Duration for Flower Induction in Soybean1
Authors: Shanmugasundaran S. , Tsou Samson C. S. 
Published: July 2010

A photoperiod sensitive (sensitive) soybean [Glycine max (L.) Merr.] line and photoperiod in sensitive (insensitive) line were used to determine the critical seedling stage before possible floral induction and the length of photoinduction required for anthesis. Seedlings of each entry were grown in pots and subjected to either a 10‐ hour or 16‐hour photoperiod. Beginning 3 days after emergence, two pots per entry in the 10‐hour room were exchanged daily with two pots from the 16‐hour photoperiod. No detectable differences between treatments were observed in the flowering time of the insensitive fine. However, the sensitive line exhibited the following: (i) The number of days to first flowering was not affected by the transfer from a 16‐hour to a 10‐hour photoperiod up to 9 days after emergence; (ii) Plants moved from a 10‐hour to a 16‐hour photoperiod before 36 days after emergence did not flower, indicating that induction was completed at 36 days after emergence; (iii) The earliest anthesis occurred 46 days after emergence.Therefore, we concluded that the induction period was 27 short days (10 hours) and that anthesis occurred 10 days after the completion of induction. The critical time to begin induction was 9 days after emergence for the sensitive line.
Identifying Turgor Responses of Water‐Stressed Cotton to Rapid Changes in Net Radiation Using Spectral Analysis1
Authors: Davis Jerry M. , Huck Morris G. 
Published: July 2010

The kinetics of stem shrinkage and swelling in response to changes in the radiation loading of field‐grown cotton (Gossyplum hirsutum L.) plants were examined by time series spectral analysis. This technique involves determination in the frequency domain of the relationship between two time series events. The type and degree of relationship a.re assessed by computing the squared coherency, phase, and gain spectra relating events in the measured net radiation and stem diameter data sets. The squared coherency spectrum shows the statistical strength of the relationship between events in the two time series, while the grain spectrum indicates the amount of response, or the mm of change in stem diam. eter resulting from a unit change in radiation intensity at each frequency. The phase spectra show the relative positions between maximum points in the two time seriesPlants growing under conditions of water stress respond to changes in radiation much more rapidly than those growing on well‐watered, deep soils. Although low frequency (slow) shrinkage response may be caused factors affecting both evapotranspiration from the leaves and root water uptake, high frequency (rapid) shrinkage or swelling responses are probably controlled exclusively by alterations in the rate of water loss because of the water storage capacity of the plant itself.
Nitrate‐Reductase Activity and Grain Yield of Maize Cultivar Hybrids1
Authors: Fakorede M. A. B. , Mock J. J. 
Published: July 2010

Nitrate‐reductase activity (NRA) has been suggested as an indirect selection criterion for grain yield in maize (Zea mays L.). This assumes that because of linkage or pleiotropism selection for higher levels of one of these traits would result in a correlated positive response in the other. We tested this hypothesis with maize cultivar hybrids obtained from two recurrent selection programs for improved grain yield.Five maize cultivar hybrids [BSSS(R)CO ✕ BSCB1 (R)CO, BSSS(R)C5 ✕ BSCB1(R)C5, and BSSS(R)C7 ✕ BSCB1(R)C7 from a reciprocal recurrent selection program involving Iowa Stiff Stalk Synthetic (BSSS) and Iowa Corn Borer Synthetic #1 (BSCB1), and BS12CO ✕ B14A and BS12C6 ✕( B14A from a half‐sib family selection program with the open‐pollinated cultivar ‘Alph’ (BS12)] were grown in 1975 and 1976 at four levels of fertilizer N (0, 90, 180, and 270 kg N/ha) and two plant densities (39,500 and 98,800 plants/ha) in Experiment I. Also, CO )✕ CO and C7 ✕ C7 from the reciprocal recurrent selection program and the hybrids from the half‐sib program were grown in 1975 and 1976 at 59,300 and 98,800 plants/ha with 178 kg N/ha (Experiment II). We assayed NRA by the in vivo technique during the vegetative, anthesis, and grain‐filling stages of development.Our results showed that average NRA did not change with selection for increased grain yield in the reciprocal recurrent selection program, but selection for improved grain yield in BS12 (half‐sib selection program) was associated with decreased NRA.
Effects of Bean Association on Yields and Yield Components of Maize1
Authors: Francis C. A. , Flor C. A. , Prager M. 
Published: July 2010

Maize (Zea mays L.) in monoculture and in association with bush and climbing beans (Phaseolus vulgaris L.) was evaluated at CIAT in the Cauca Valley, Colombia (1,000 m elevation, 4° N lat). Since small farmers in the Andean zone plant maize at low densities in association with beans, the objectives were to measure the effects of the associated legume crop on maize yields and net returns.Maize yields did not differ significantly between monoculture and associated cropping at harvest densities from 3 to 4 ✕ 104 plants/ha, in trials with different bean cultivars, bean plant densities, planting systems, and relative dates of planting of the two crops. There were no significant differences between systems in the following maize components: ear length, ear and cob diameter, row number, shelling percent, weight per 100 seeds, harvest index, prolificacy index, total biological yield, or plant height. Lodging was less severe in an associated culture of maize, wiht an average of 16.4% in association compared to 28.7% in monocrop over six trials. Less fall armyworm (Spodoptera frugiperda Smith) attack was observed in associated crop maize than in monoculture. Efficiency of land use increased with addition of beans to the system, and highest net income was achieved with associated cropping systems. These results may help to explain why small farmers continue to utilize associated cropping systems in the tropics of Latin America.
A Model for Evaluating Progress from Recurrent Selection1
Authors: Smith O. S. 
Published: July 2010

A model was developed to study the relationship between the change in the mean and changes of allelic frequencies in improved populations arising from recurrent selection. The change in the mean in the improved populations is a function of Δp, the weighted average change in allelic frequency, α, the average effect of a gene substitution in the base population, and R, the change in inbreeding depression in the improved populatious.The model is illustrated by use of data from two studies designed to evaluate recurrent selection methods in corn (Zea mays L.). The analysis indicated significant changes in the weighted average change in allelic frequency and in the amount of inbreeding depression in these populations. Direct and indirect effects of selection were not significantly different in most of the populations studied.
The Ideal Cassava Plant for Maximum Yield1
Authors: Cock J. H. , Franklin D. , Sandoval G. , Juri P. 
Published: July 2010

A series of trials were carried out using cassava (Manihot esculenta Crantz). Crop growth rate increased with leaf area (LAI) up to LAI 4; root growth rate increased up to LAI 3 to 3.5, then declined. Leaf area index is determined by leaf size, leaf formation rate, and individual leaf life. Leaf size reached a maximum 4 months after planting and then decreased; the maximumw as a varietal character. Leaf life was reduced by shading but in full daylight was determined by a variety. Leaf formation rate per shoot apex showed little genetic variation and declined with time; large differences in leaf formation rate per plant were determined by differences in branching pattern. Top growth had preference over root growth, and root sink was not limiting when root number per plant was nine or more.A computer program was written to implement a dynamic growth model which suggests that high‐yielding plants will branch late in life and possess large leaves and long leaf life. Potential yields of more than 25 metric tons/ha per year of dry roots are obtainable at 400 to 450 g cal cm−2 day radiation.