bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the Components of Area Growth of Bean Root Systems1
Authors: Fiscus Edwin L.
Published: July 2010

Root and leaf surface areas were measured on green bean (Phaseolus vulgaris L. cv. Ouray) plants, with light intensity (photosynthetic photon flux density, PPFD) as the major growth variable, to determine how various sizes of roots are related to water transport and growth rates of whole‐root systems. Plants were grown in aerated nutrient solution for 41 days in a greenhouse. Two light intensities were used: 425 and 320 μE m−2 sec−1 Leaf area:root area ratios, distribution of root sizes, and the fraction of the total root surface area of each root class were determined. All of these parameters remained stable for plants with leaf and root areas greater than 1,000 cm2 and they were unchanged by light intensity or growth rate. On the basis of previous data the mean root system hydraulic conductance (Lp) appeared to be keyed to plant size rather than age. The conductance was very low in small plants, increased about sixfold and peaked when the root systems reached approximately 1,000 cm2 surface area. For plants larger than 1,000 cm2, when the root size distributions were stabilized, conductance gradually declined, probably because of suberization or some other growth‐related factor. Plants grown at lower light intensity showed the same pattern of relationships between root system size, root size distribution, and hydraulic conductance except that the overall Lp was consistently lower for plants of similar sizes.
14C‐Labelled Assimilate Utilization by Soybeans Grown with Three Nitrogen Sources1
Authors: Pearen J. R. , Hume D. J.
Published: July 2010

The use of a non‐destructive method of determining 14C content of soybean plants after labelling allowed the fate of this 14C, including proportions distributed to various plant parts or lost in respiration, to be studied. Plants grown in buckets in the field with Low‐N, nitrate (NO−3), or ammonium (NH+4) N sources were allowed to assimilate 14CO2 in photosynthesis at five stages in ontogeny. Plants were harvested after 1 week or at maturity and 14C in plant parts was determined. In the first week after each labeling, NO−3‐N plants lost an average of 14% of their 14C, compared to 23% in NH+4‐N plants and 34% in Low‐N plants fixing N2. Between labellings and maturity, average 14C losses were 40% in NH+4‐N plants, 45% in NO−3‐N plants, and 52% in Low‐N plants. The largest proportion of the assimilated 14C was either lost in respiration or contained in plant parts that were growing rapidly at labelling. Nodules of Low‐N plants contained more than those grown on NO−3‐N or NH+4‐N 1 week after labelling at stages R1 and R2.5. The percentages of assimilated at stages V4, R1, R2.5, R4 and R5.5 which were recovered in beans at maturity were 2.2, 3.7, 5.5, 13.8 and 36.5% respectively. Losses of 14C from vegetative parts between 1 week after early labelllngs and maturity were mainly a result of respiration rather than retranslocation to beans.
Seasonal Variation in Flowerbud Gossypol Content in Cotton1
Authors: Dilday R. H. , Shaver T. N.
Published: July 2010

Flowerbud gossypol content has been associated with a degree of host plant resistance in cotton (Gossypium hirsutum L.), but efforts to increase and stabilize genetic levels have been hindered by an apparent seasonal variation in gossypol content, A 4‐year study (1974 to 1977) of two lines having flowerbuds with high levels of gossypol and two cultivars with normal levels of gossypol revealed a significant change in gossypol contents both within and between seasons. The gossypol contents in 1975 were significantly greater than those in 1974 and 1977 for the two lines having flowerbuds with high levels of gossypol. Also, a significant withinseason variation in gossypol contents occurred among all four genotypes that were tested. The coefficient of correlation comparing gossypol contents of the two lines having flowerbuds with high gossypol levels and of the two cultivars were 0.82 and 0.79, respectively. Whereas, the coefficient of correlation comparing the gossypol contents of the cultivars with the high gossypol lines were all less than 0.55. These data show that comparisons of flowerbud gossypol levels within a season should be based on seasonal averages or should be made as close to the same date as possible. There should not be more than a 7‐day interval between dates if direct comparisons are to be made among entries within a single season.
Response to Selection for Resistance to Four Diseases in Two Corn Populations1
Authors: Miles J. W. , Dudley J. W. , White D. G. , Lambert R. J.
Published: July 2010

Index selection designed to maximize gain in resistance to a single disease and selection for resistance based on disease score, per se, were evaluated. Responses to index and per se half‐sib family selection for resistance to northern corn leaf blight (caused by Helminthosporium turcicum Pass.), Diplodia stalk rot [caused by Diplodia maydis (Berk.) Sacc.] and anthracnose leaf blight and stalk rot [caused by Colletotrichum graminicola (Ces.) Wils.] in two corn (Zea mays L.) populations (RSL and RSSSC) were measured by comparing the performance of selected bulks with base populations in artificially inoculated evaluation trials in 2 years.

Modified ear‐to‐row index selection was effective in increasing resistance to northern corn leaf blight in both populations, and to Diplodia stalk rot and to anthracnose stalk rot in one population each. Half‐sib selection on disease score per se in one population (with recombination of remnant seed) was effective in increasing resistance to northern corn leaf blight, anthracnose leaf blight and anthracnose stalk rot. No consistent correlated response in grain yield (measured in uninoculated evaluation trials) to selection for disease resistance was found.

Observed response to selection agreed well with predicted response based on variance and covariance estimates obtained from previous half‐sib evaluation experiments. Selection on indexes constructed from data on several traits and designed to maximize gain in disease resistance was no more effective than selection on disease score per se.
Genetic Male Sterility in Sesame: Reproductive Characteristics and Possible Use in Hybrid Seed Production1
Authors: Osman H. Elg. , Yermanos D. M.
Published: July 2010

Male‐sterile plants, producing nonviable pollen, were recovered from a Venezuelan seed stock of sesame (Sesamum indicum L.). Grosses between these plants and male‐fertile cultivars produced a proportion of F2 segregants that were also male‐sterile. Seed set on male‐sterile plants following hand pollinations with normal pollen was high indicating that these plants were female‐fertile. Greenish anther color at pollen dehiscence distinguished male‐sterile from male‐fertile plants, the latter having whitish anthers. Microscopic examinations revealed that sterile anthers had no endothecium and that their pollen lacked exine and had no definite wall surface structure. Observations on flower morphology of F2 plants indicated that the male‐sterility trait is stable, easily maintained under greenhouse and open field conditions and positively recognizable 3 to 4 days before anthesis. The male‐sterility described here can be used for commercial hybrid seed production which could lead to major increases of sesame yield per hectare.
Diurnal Leaf Elongation of Contrasting Tall Fescue Genotypes1
Authors: Volenec J. J. , Nelson C. J.
Published: July 2010

Leaf elongation rate (LER) of tall rescue (Festuca arundinacea Schreb.) leaves is associated with tillering rate and forage yield. We performed two experiments. Objectives of Exp. I were to determine if differences in LER among genotypes were due to differential growth during the photoperiod and dark period, and of Exp. II to determine the relationship between leaf water potential and LER. Plants were grown in a controlled environment chamber with a 14‐hour photoperiod and a constant temperature of 21 or 23 C measured at the leaf intercalary meristem. Potentiometers were used to measure leaf elongation of genotypes selected for high yield per tiller (HYT, rapid LER) and low yield per tiller (LYT, slow LER). In Exp. II, stomatal diffusive resistance, leaf water potential, and LER of these genotypes were measured.

Mean LER for the HYT genotype (0.9 mm hour‐1) throughout two 48‐hour periods was greater than that for the LYT genotype (0.6 mm hour‐1). Mean LER of both genotypes was significantly higher during the dark periods than during the photoperiods, averaging respectively 1.1 and 0.7 mm hour‐1 for the HYT genotype, and 0.7 and 0.5 mm hour‐1 for the LYT genotype. The 67% increase in LER during the dark period over that during the photoperiod for the HYT genotype was significantly greater than the 33% increase for the LYT genotype. Brief, but substantial increases and decreases in LER coincided with the time the lights went off and on. This response was associated closely with times of increases and decreases in stomatal diffusive resistance, and subsequent changes in leaf water potential. Leaf water potential was higher for the HYT than for the LYT genotype and was associated with LER of both genotypes. In Exp. I, LER averaged 1.3 and 0.8 mm hour‐1 for the HYT and LYT genotypes, respectively, during a 41‐hour dark period. These rates were similar to those maintained during the normal 10‐hour dark periods, and we concluded that daily photosynthate production was not needed to maintain high LER in the dark. Thus, the difference in LER between genotypes was due, in part, to a genotype by leaf water potential interaction which allowed the HYT genotype to more effectively utilize the dark period.
Correlation of Mitochondrial DNA Restriction Endonuclease Patterns with Sterility Expression in Six Male‐Sterile Sorghum Cytoplasms1
Authors: Conde M. F. , Pring D. R. , Schertz K. F. , Ross W. M.
Published: July 2010

Six cytoplasmic male‐sterile sorghum, Sorghum bicolor (L.) Moench, lines (KS34 through KS39), which have cytoplasms from sources other than the milo group, were tested for fertility expression in F1 hybrids produced with nine lines, and their organelle DNAs were examined by restriction endonuclease fragment analysis. Three of the KS lines had cytoplasms indistinguishable from milo male‐sterile cytoplasm; the remaining three lines differed from milo both in fertility response and their mitochondrlal DNA restriction patterns. Chloroplast DNA restriction patterns of all six KS lines were indistinguishable from that characteristic of milo chloroplast DNA. The results indicate a relationship between mitochondrial DNA and genetic behavior of the male‐sterile cytoplasms. These cytoplasms may be useful in broadening the cytoplasmic base of hybrid sorghum production.
Use of Hypodermic Inoculations of Alfalfa for Identifying Host Reactions and Races of Colletotrichum trifolii1
Authors: Ostazeski S. A. , Elgin J. H.
Published: July 2010

A hypodermic inoculation technique was used to nondestructively determine the differing resistance to race 1 and race 2 of alfalfa plants in breeding and genetic studies. Stem inoculations were made with hypodermic syringes fitted with 23‐27 gauge needles. Conidial concentrations ranged from 1 to 9 million conidia/ml. Symptoms could be classified in 10 to 14 days. Susceptible stems formed large lesions at the inoculation site and wilted and collapsed. Resistant stems continued to grow normally with no lesion development. Hypodermic inoculations resulted in disease resistance reactions similar to those obtained with conventional spray inoculation techniques. We have isolated clones with the following combinations of resistant ( + ) and susceptible (−) reactions to race 1 and race 2, respectively: + +, + −, and − −.
Visual Indicators of Physiological Maturity of Hard Red Spring Wheat1
Authors: Hanft J. M. , Wych R. D.
Published: July 2010

Field experiments were conducted in 1979 and 1980 to identify visual indicators that coincide with physiological maturity (PM) and 95% maximum kernel dry weight (95% MKW) in hard red spring wheat (Triticum aestivum L.). Dates of PM and 95% MKW were calculated from polynomial regression equations fitted to dry weight accumulation data from eight genotypes differing in several agronomic traits. In 1980, kernels were divided into three groups according to their position on the spike (bottom, middle, and top) to determine the order in which kernels achieve their maximum dry weight.

The mean number of days from anthesis to 95% MKW and PM ranged from 22.3 to 33.7 and 27.9 to 40.1, respectively, depending upon planting date and genotype. Kernels matured, in order, from the top of the spike down. The time of 95% MKW preceded PM by about 7 days. Of the 13 visual characteristics observed during the grain‐filling period, first appearance of the pigment strand in the crease most closely coincided with the calculated date of PM. Complete loss of green color from the glumes also occurred close to PM. Complete loss of green color from the flag leaf most consistently coincided with the time of 95% MKW. An abrupt drop in kernel moisture content also occurred at 95% MKW. Complete loss of green color from the flag leaf could, therefore, be used as an indicator of the commencement of rapid kernel dry‐down and the final stage of grain filling which ends when the pigment strand is first visible and the glumes have lost all green color. Kernel moisture percentage at PM and 95% MKW was too variable to be considered a reliable indicator of either PM or 95% MKW.
Effect of Soybean Mosaic Virus on Root Volume and Dry Weight of Soybean Plants1
Authors: Keeling B. L.
Published: July 2010

The effect of soybean mosaic virus (SMV) on root volume and dry weight of soybean [Glycine max (L.) Merr.] seedlings was determined in two environments (greenhouse and controlled environment chamber). Root volume of susceptible cvs. ‘Bragg’ and ‘Tracy’ was reduced up to 61% 30 days after 10‐day‐old seedlings were inoculated. The reduction in dry weight of roots and top portion of Bragg and Tracy seedlings ranged from 38 to 59%. Root volume of D73‐7725 (resistant) was reduced 18% by SMV when the plants were grown in a controlled environment chamber but was not reduced in the greenhouse environment.
Theory for Transfer of Alleles1
Authors: Dudley J. W.
Published: July 2010

The objectives of this paper are to provide a theoretical framework for developing methods for incorporation of favorable alleles governing quantitative traits from exotic germplasm into adapted populations and to present computer simulation results evaluating the theory. Theoretical considerations suggest that the results apply to either improvement of an inbred line by adding favorable alleles from another line or to addition of favorable alleles from an exotic source to an adapted synthetic.

The results suggest that 1) if one parent has more loci containing favorable alleles than the other, at least one generation of backcrossing to the recipient population prior to initiation of selection will enhance the probability of recovering a population which outperforms the better parent or a llne better than the best llne which could be isolated from the better parent, 2) selection starting in the appropriate generation will usually be necessary to either improve the population mean to the desired level or to increase to a reasonable level the probability of obtaining a superior inbred line, and 3) the more diverse the parents, the more useful one or more generations of backcrossing becomes.
Breeding for Resistance to the Sugarbeet Root Maggot1
Authors: Thuerer J. C. , Blickenstaff C. C. , Mahrt G. G. , Doney Devon L.
Published: July 2010

Thirty‐six genetically diverse sugarbeet (Beta vulgaris L.) lines were evaluated to determine their potential resistance to the sugarbeet root maggot, Tetanops myopaeformis Roder. Significant and relatively consistent differences in maggot damage were noted over 3 years. Damage ratings of F1 crosses of resistant ✕ susceptible lines tended to be intermediate between those of the parents. Selection for high‐ and low‐maggot damage showed a linear trend in increasing and decreasing maggot damage, respectively. The average decline in the low‐damage selection was approximately 5% per cycle. After five cycles of selection, there was no change in the rate of decline, indicating that further selection progress can be made. A greenhouse test confirmed field designations of resistant and susceptible genotypes. A low‐damage inbred had lower maggot survival, smaller maggot weight, lower damage ratings, and greater root weight than a susceptible line.
Developing Superior Inbreds from Exotic Germplasm of Pearl Millet1
Authors: Burton Glenn W.
Published: July 2010

This study was designed to compare two methods of developing pearl millet, Pennisetum amerlcanum (L.) Leeke., inbreds from exotic germplasm: selfing within an introduction (I) or selfing within F1 hybrids of the introduction crossed with an elite inbred (I × E). Elite inbreds Tilt (T) 8, T13, T18, T23, T26 (T18A and T23A), 71 introductions from India, and 250 introductions from Nigeria were used in this study. Bulking of selfed seed from single heads of 12 to 15 plants, used to plant each succeeding generation, exerted some selection for selfed seed production. No other selection was practiced. Forage yields of FI hybrids of I and I × E inbreds crossed on T18A and T23A (cytoplasmic male‐sterile inbreds) were used to assess 321 I and I × E inbreds developed. Results indicate that crossing exotic germplasm with elite lines before selfing may be expected to increase inbred seed yields up to 50% and materially reduce the loss of inbreds due to poor seed set. Selection for other elite traits, not practiced here, could have given added advantage to I × E inbreds. Although the greatest difference between I and I × E hybrid forage yields (1,232 kg/ha) favored I × E inbreds, I × E inbreds generally gave no higher yielding hybrids than I inbreds.
Assessment of Acetylene Reduction by Sainfoin and Alfalfa over Three Growing Seasons1
Authors: Krall J.M. , Delaney R.H.
Published: July 2010

Sainfoin (Onobrychis viciifolia Scop.) has many positive characteristics as a forage legume, but frequently exhibits poor stand persistence. Insufficient nitrogen (N2) fixation has been suspected contributing to the stand persistence problem in sainfoin. Nitrogen fixation (acetylene reduction) rates of sainfoin have been reported for seedling plants, however, there is no information on fixation rates for established stands.

A root box technique which allowed for the measurement of acetylene reduction on intact perennial plants for several growing seasons was used. Acetylene reduction of sainfoln and alfalfa (Medicago sativa L.) grown in soils collected from six existing sainfoin fields was measured at various stages of plant growth over three growing seasons. Sainfoin acetylene reduction rates were 36 to 75 % greater than alfalfa with the difference increasing with plant age.

Percent non‐structural carbohydrates (NSC) were 10 % higher alfalfa taproots compared to sainfoin after the third growing season. Total NSC of sainfoin and alfalfa taproots was 1.8 and 6.9 g, respectively. Visual observation indicated that root and crown diseases resulted in significant mortality of sainfoin.

Results indicated that acetylene reduction of sainfoin was superior to alfalfa while a consistent trend favoring a particular soil was not found. Carbohydrate storage and disease susceptibility may contribute more to the stand persistence problem of sainfoin than poor N2 fixation.
Effects of Recurrent Phenotypic Selection for High and Low Photosynthesis on Agronomic Traits in Two Maize Populations1
Authors: Crosbie T. M. , Pearce R. B.
Published: July 2010

Selection for high or low photosynthetic rate in plant populations may influence important agronomic traits. We studied the effects on agronomic traits of five cycles of recurrent phenotypic selection (RPS) for high CO2‐exchange rate (CER) in two maize (Zea mays L.) populations and three cycles of selection for low CER in one population.

Estimates of the weighted‐average change in allelic frequency (Δpα) showed significant reductions in plant and ear heights and significant increases for percentages of plants not root and stalk lodged after five cycles of RPS for high CER in BSULl(RPH). Estimates of Δpα after RPS for high CER in BSUL2(RPH) were significant only for percentage dropped ears, which increased slightly across five cycles of selection. Estimates of Δpα for RPS for low CER in BSUL2(RPL) indicated that days to 50% pollen shed had increased significantly across cycles. Changes in grain yield were not significant for any population, but Δpα for low CER selection in BSUL2(RPL) was significantly greater than Δpα for high CER selection in either BSULl(RPH) or BSUL2(RPH). Estimates of Δpα for grain yield of both BSULl(RPH) or BSUL2(RPH) were negative, but not statistically significant at the 5% probability level.
Evaluation of Honeycomb Selection for Single Plant Yield in Durum Wheat1
Authors: Mitchell J.W. , Baker R.J. , Knott D. R.
Published: July 2010

Fasoulas' (1973) honeycomb design was used to select for high and low yield among single F2 plants in three crosses of durum wheat, Triticum turgidum L. var. durum, each planted at interplant spacings of 30 and 60 cm. Response to selection, measured by yield of replicated F3 bulks of F4 lines, was significant for all three crosses when grown at 60 cm spacing and for two of the three crosses when grown at 30 cm. Significantly greater response in the downward than in the upward direction was observed in one cross. Correlations between 1979 single plant yields and 1980 plot yields in the one cross where progeny of all plants were tested indicated i) that selection was slightly more effective at wider spacing, ii) that Fasoulas' method was marginally superior to mass selection based on unadjusted single plant yields, and iii) that heritability of single plant yield was 13 to 17%. Average response to single plant selection for yield was 4% of the mean yield in solid seeded plots.
Three Cycles of Simple Recurrent Selection for Early Heading in Winter Wheat1
Authors: Avey D. P. , Ohm H. W. , Patterson F. L. , Nyquist W. E.
Published: July 2010

A recurrent selection program in winter wheat (Triticum aestivum L. em Thell) was initiated by intermating 12 two, three, and fourway hybrids involving 16 cultlvars and lines to determine gain from selection for early heading, to develop genotypes which are earlier heading than currently available types, and to demonstrate the feasibility of recurrent selection in wheat improvement. The hybrid population produced by intermating these 12 hybrids was the nonselected base population. Three cycles of selection and intermating of S0 plants were carried out in the greenhouse. Hybrid plants from each of the three cycles, S1 plants or the selfed progeny from S0 plants selected to intermate in each cycle, plants of the base population, and the 16 parents were planted in the field at two locations in fall of 1979.

The largest gain from selection was realized in the first selection cycle. Additional progress was made in the following two cycles, but at slower rates. Mean days to heading after 30 April for the base population were 14.2 and 23.4 at Sullivan and Lafayette, Indiana, respectively. Mean days to heading for hybrid populations from cycles 1, 2, and 3 at the 10% selection level were, respectively, 12.0, 11.7, and 11.2 at Sullivan; and 22.2, 21.6, and 21.6 at Lafayette.

Realized heritability estimates from cycle 1 were 0.92 and 0.49 for the selected S0 populations, and 0.31 and 0.36 for the selfed progenies at Sullivan and Lafayette, respectively. The heritabilitles of cycles 2 and 3 were lower, 0.24 to 0.32, and were similar for the S0 and S1 generations. These data suggest that in the first cycle, selection acted largely on major genes which showed some nonadditive gene action, while selection in cycles 2 and 3 acted on minor genes governed by additive and/or additive × additive effects.Recurrent selection for early heading in winter wheat was effective in shifting the population means in the desired direction.
Comparative Glutamine Metabolism in Tobacco Callus and Leaf Tissues1
Authors: Lazar M. D. , Collins G. B.
Published: July 2010

Tobacco (Nicotiana tabacum L.) callus tissue was found to contain at least a thirty‐fold higher concentration of free glutamine than leaves from greenhouse‐grown plants of the same genotype. The most important factor contributing to the observed difference in glutamine pool size was exogenous ammonium concentration. Also, the specific activities in cell‐free extracts of the ammonium assimilating enzymes, glutamine synthetase and glutamate dehydrogenase assayed at nonlimiting substrate concentrations were maximal in both tissues at exogenous ammonium concentrations of approximately 0.1 to 0.3 mM for glutamine synthetase and 10.0 to 30.0 mM for glutamate dehydrogenase. Labeling callus tissue with 14C‐glutamate allowed the calculation of approximate rates of in vivo transfer of carbon skeletons from glutamate to glutamine which were consistent with the effects of in vivo ammonium concentration on enzyme activities observed in cell‐free extracts.

The results indicate that under conditions of ammonium limitation in either tissue, the glutamine synthetase/glutamate synthase pathway is important to ammonium assimilation. The data suggest that in vivo activities of glutamlne synthetase, glutamate synthase and glutamate dehydrogenase in both leaf and callus tissues are regulated by ammonium concentration.
Maysin Content of Silks of Nine Maize Genotypes Grown in Diverse Environments1
Authors: Widstrom N. W. , Waiss A. C. , McMillian W. W. , Wiseman B. R. , Elliger C. A. , Zuber M. S. , Straub R. W. , Brewbaker J. L. , Darrah L. L. , Henson A. R. , Arnold J. M. , Overman J. L.
Published: July 2010

Maysin is a flavone glycoside that exhibits antibiotic activity toward corn earworm [Heliothis zea (Boddie)] and can be present the silks of maize (Zea mays L.). Nine maize genotypes were grown at four locations in 1979 and five locations in 1980 and evaluated for relative content of maysin in their silks. Differences among maize genotypes for maysin content were highly, significant. ‘Golden Cross Bantam’ (corn earworm susceptible) and experimental hybrid 471‐U6 ✕ 81‐1 (corn earworm tolerant) consistently had the lowest relative maysin content whereas P39 ✕ ZC 2451, a susceptible sweet corn ✕ resistant dent corn cross, consistently had the highest relative maysin content although a significant genotype by environment interaction was present. When genotype maysin means among environments were correlated, the genotypes grown in Missouri demonstrated the least agreement with genotype maysin means from other environments. The relative maysin content of silks was highest in Georgia and lowest in Hawaii, and a significantly lower level occurred in 1980 than in 1979. At this time, no biological explanation can be offered for environmental differences in average maysin content.
Effect of Shading on Nonstructural Carbohydrates and their Turnover in Culms and Leaves during the Grain Filling Period of Spring Wheat1
Authors: Judel G. K. , Mengel K.
Published: July 2010

The effect of light intensity on the content of nonstructural carbohydrates in leaves and culms and on grain yield of spring wheat (Triticum aestivum L., ‘Kolibri’) was studied during the grain filling period. Light intensity was reduced by shading the plants with muslin after the onset of anthesis. At this time, the nonstructural carbohydrate present in highest quantity in the vegetative plant material was sucrose. Later the fructosans showed the highest concentrations in leaves and culms. In both treatments an accumulation of polysaccharides, particularly of fructosans, occurred in the culms during the first 2 to 3 weeks after anthesis, suggesting that at this stage of grain filling, net photosynthesis was higher than assimilate consumption for grain filling. The depletion of nonstructural carbohydrates at maturity was of a much higher order in the culms and leaves of the shaded plants while these parts in the control plants still contained a quantity of nonstructural carbohydrates which amounted to about 10% of the grain weight. Grain yield was about 20% lower in the shaded plants as compared with the control plants. The results conclusively show that fructosans are the most important storage carbohydrates in leaves and culms during grain filling. Mobilization of storage carbohydrates such as fructosans and starch is a major process which may limit grain production.
A Multiplicative Selection Index Applied to Four Cycles of Full‐Sib Recurrent Selection in Maize1
Authors: Compton W. A. , Lonnquist J. H.
Published: July 2010

A condensed form of full‐sib family recurrent selection in maize (Zea mays L.) 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.
Variability of Seedling Growth Characteristics among Oat Genotypes1
Authors: Murphy C. F. , Long R. C. , Nelson L. A.
Published: July 2010

The objectives of this investigation were to (i) estimate the range of variability present for the oat (Avena sativa L.) seedling characteristics, including shoot length and weight and root length, weight, and volume; and (ii) to determine how these characters vary among groups of cultivars representing different breeding eras.

Fifty‐two cultivars were chosen to represent a wide range of genetic backgrounds and breeding eras. The cultivars were classified as belonging to one, or more, of the following categories: I—spring‐sown, II—fall‐sown, III—sources of crown rust resistance, IV—earliest introductions, V—early selections, VI—early hybrid selections, VII—intermediate hybrid selections, VIII—modern hybrid selections, IX—sources of straw strength, X—diploid, XI—dwarfs, and XII—very tall. Comparisons were made between cultivar categories.

Ranges in cultivar means expressed as a percentage of the grand mean for the five characters were: shoot length, 101.9 % ; root length, 81.5%; root volume, 81.8%; shoot weight, 113.3%; and root weight, 75.0%. Simple correlations were relatively high among all characters, ranging from 0.48 for shoot length and root volume to 0.84 for root volume and root weight (determined over all 52 cultivar means).

The spring‐sown genotypes gave consistently higher values for the five growth characters than did the fall‐sown genotypes. Lines that are sources of crown rust resistance were genetically inferior in their seedling growth responses. The effects of selection pressure (for other characters) during the time progression from the earliest introductions to the modern hybrid selections were pronounced. The most obvious trend was toward greater root development in the modern selections. Shoot lengths were slightly reduced over the time span.
Yield Stability of Guar Breeding Lines and Cultivars1
Authors: Stafford R. E.
Published: July 2010

Guar [Cyamopsis tetragonoloba (L.) Taub.] cultivars and breeding lines were evaluated at seven test‐sites in Texas and southwest Oklahoma for 3 years and at nine test‐sites for 5 years. Genotypes exhibited variation for maturity classes and primary growth habit. Data for 22 genotypes were analyzed to determine yield stability parameters. Based on those parameters, genotypes G‐3, G‐4, G‐5 and G‐12 were most stable in the early testing period, while G‐19 was most stable during the latter testing period. Medium maturing genotypes exhibited greater stability than either early or late maturing genotypes. Growth habit did not affect stability. Low coefficients of determination (r2) for most genotypes suggested a sizeable proportion of variability for yield could be attributed to environmental effects.
Allozymic Variability among Maize Inbred Lines and Hybrids: Applications for Cultivar Identification1
Authors: Cardy B. J. , Kannenberg L. W.
Published: July 2010

The potential use of electrophoretically detected allozymic variability for maize (Zea mays L.)cultivar identification was assessed by surveying the variability of 12 enzyme systems, involving 22 loci, among 110 public inbred lines and 153 commercial hybrids used in Canada. Summed over loci, 55 and 56 alleles were detected among the inbred lines and hybrids, respectively. All but a few alleles were common to both groups. For most loci, several alleles were observed at low frequencies among the inbred lines and the hybrids. These rare alleles, as well as unique combinations of alleles within (hybrids only) and among loci, identified 88 inbred lines (80%) and 146 hybrids (94%) with unique fingerprints. Four additional fingerprints were observed among the remaining nine hybrids. Unexpected allozymic variability was observed within 59% of the hybrids. Comparisons of the apparent hybrid type (single, threeway, double, etc.) as determined electrophoretically with the hybrid type indicated by the company showed discrepancies for 32% of the hybrids. Our results suggest that sufficient allozymic variability exists among maize cultivars to be useful for cultivar identification.
Application of a Dominant Male‐Sterile Allele to the Improvement of Self‐Pollinated Crops1
Authors: Sorrells M. E. , Fritz S. E.
Published: July 2010

Because of the difficulty of making large numbers of crosses, few breeders of autogamous crops have seriously considered recurrent selection for population improvement unless genetic male‐sterility genes are available to facilitate crossing. Procedures using recessive male‐sterility genes have been described. The purpose of this paper is to point out how dominant male‐sterility genes, which have been found in cotton and wheat, can facilitate cyclical methods. Mass selection, half‐sib selection, S1 selection, combinations of these schemes, and backcrossing can be greatly expedited by the use of the dominant male‐sterile allele. Important characteristics of the dominant male‐sterile are: 1) a generation of selfing is not required to obtain segregates that breed true for fertility; and 2) progenies of male‐sterile plants always segregate 1:1 for the dominant malesterile allele. The dominant male‐sterile allele has not been put in other cytoplasms because plants carrying it must be used as females; however, it may be possible to identify partial steriles that can be used as males to transfer the allele to another cytoplasm. Random outcrossing may be restricted in some schemes and could be promoted by alternating male rows, higher plant densities, and split planting dates. The dominant male‐sterile allele should prove to be an effective tool for long‐term population improvement and for maintaining genetic variability.
Effect of Honeybees on Crossing Percentage and Pod‐Set in Guar1
Authors: Stafford R. E.
Published: July 2010

The effect of honeybees (Apis mellifera L.) on crossing percentage and pod set in guar [Cyamopsis tetragonoloba (L.) Taub.] was studied by comparing crossing blocks caged with and without bees and open‐field crossing. Crossing was increased threefold in the block with honeybees, compared to the open‐field and absence‐of‐bees crossing blocks. Maximum detected crossing using the glabrouspubescent marker was 13.3%. Pod set in open‐field and with‐bees crossing blocks was significantly higher than where bees were excluded; however, seeds per pod was greatest where bees were excluded. Cultivars differed significantly in pods per plant, seeds per pod, and amount of cross pollination.
Partitioning Soybean Seed Yield Components1
Authors: Herbert S. J. , Litchfield G. V.
Published: July 2010

Little is known about the nodal distribution of seed yield components in short‐seasoned soybeans [Glycine max (L.) Merr.]. This study was initiated to determine the effect of row width and plant density on the seed yield and yield components at each node of ‘Evans,’ a group O soybean cultivar. Field trials were planted in late May 1979 and 1980. The 25, 50 and (in 1980 only) 75 cm row widths were factorially arranged with plant densities of 25, 80 and 135 seeds/m2 in a fine sandy loam (Typic Udifluvents). Seed yield increased by 31% and 12 to 16% when row width was decreased from 75 and 50 cm, respectively, to 25 cm. Seed yield increased 13 to 27% when plant density was increased from the low to the medium density. Medium and high densities had similar seed yields. Final seed yields averaged 4,110 kg/ha in 1979 and 4,950 kg/ha in 1980. The number of pods per plant and per node was the yield component most affected by increasing row width or plant density. Pod number per plant increased as row width was narrowed and decreased with increasing plant density. The number of seeds per pod and seed size showed minor changes in response to changes in row width, plant density, and node position on the plant. Nodes 5 to 9 had the greatest percentage of seed yield (36 to 67%) compared to nodes 1 to 4, 10 to 14, and 15 to 20, in all treatments except forplants in the low density, 25 cm row spacing plot where branches contributed most of the yield at the lowest main axis nodes. Branches in low densities produced 30 to 40% of the seed yield in both years, while in the medium and high densities branches contributed 5 to 16% of seed yield.
Genotypic Differences in Leaf Osmotic Potential Among Grain Sorghum Cultivars Grown Under Irrigation and Drought1
Authors: Shackel K. A. , Foster K. W. , Hall A. E.
Published: July 2010

Osmotic potential of leaves may have relevance to turgor maintenance and adaptation of plants to water‐limited environments. Studies were conducted to determine whether it is possible to detect genotypic differences in leaf osmotic potential in the field and the conditions where screening for this character would be most effective.

Consistent genotypic diffences in osmotic potential of sap expressed from frozen‐thawed leaf tissue were found during a 3‐year field trial which included 10 sorghum [Sorghum bicolor] (L.) Moench genotypes in the first year. Measurements were taken during periods of minimum and maximum water stress (predawn and midafternoon, respectively) under both frequently irrigated and water‐limited conditions. Despite highly significant genotype × environment and genotype × treatment interactions, the ranking of sufficiently contrasting genotypes was similar throughout all conditions with ‘Dwarf Redlan’ maintaining the highest and ‘M35‐1’ maintaining the lowest leaf osmotic potential.

Seasonal changes in osmotic and total water potential (pressure chamber technique) indicated progressively increasing levels of predawn turgor potential for both frequently irrigated and water‐limited treatments but progressively decreasing levels of midafternoon turgor potential. Maintenance of turgor under water‐limited relative to frequently irrigated conditions was exhibited at predawn, but not midday. The low osmotic potentials of M35‐1 resulted in higher leaf turgor, compared with Dwarf Redlan, at predawn under frequent irrigation.

It is proposed that differences in leaf osmotic potential may be used to select sorghum genotypes that exhibit contrasting water relations. Selection may be more effective under frequently irrigated conditions and during grain filling than under water‐limited environments or during early stages of growth.
In Vitro Production of Haploid Plants of Corn via Anther Culture1
Authors: Genovesi A. D. , Collins G. B.
Published: July 2010

The objectives of the present study were to confirm the Chinese reports of haploid plant production from corn microspores via anther culture and to further define conditions for improved efficiency. Various genotypes (both Chinese and U.S.A.), media and cold‐shock pretreatments of tassels were evaluated. The basal Chinese medium, designated Yu‐pei, was modified to test various organic and inorganic additives. Variations in degree and duration of cold pretreatment were studied. Highly significant differences for anthers responding with calli or embryoids were found among genotypes, media, and cold treatments. Two American germplasms, inbred Tx601 and the Armstrong variety, produced plants from cultured anthers. A 14‐day cold pretreatment of tassels was found to elicit the best response. Adding activated charcoal to the basal medium further improved response. Under optimum conditions for pretreatment and medium, 18.3% of the treated anters responded. Of those anthers responding with callus or embryoid production, a maximum of 19.2% produced plantlets. Chromosome counts of both haploid and diploid plants were obtained. A total of 20 haploid and diploid plants were grown to maturity and studied in the greenhouse. One haploid/diploid mosaic was selfed while a second pollen plant which could not be selfed was pollenated with pollen from a third anther derived plant.
Inheritance of Resistance to Stem Rust in a Selection of the Wheat Cultivar ‘Waldron’1
Authors: Williams N. D. , Miller J. D.
Published: July 2010

The hard red spring wheat (Triticum aestivum L.) cultivar ‘Waldron’ is resistant to North American strains of stem rust (Puccinia graminis f. sp. tritici). The inheritance of resistance in a selection of Waldron (Wdr‐sel) was studied to determine the number of genes affecting reaction to 15 cultures of the stem rust fungus. F2 plants from Wdr‐sell/‘Little Club’ were progeny tested by inoculating families of F3 seedlings. Infection types were used to classify each F2 family into homozygous susceptible (S), segregating resistant and susceptible seedlings in a monogenic ratio (Seg), and inseparable (I). Segregation ratios were tested by chi‐square for goodness of fit to ratios of 4n‐2n‐1 (1):2n(Seg):l(S), where n is the number of segregating genes for resistance. Wdr‐sel had one gene for reaction to culture A‐14NW (race 29, HNH) and two genes for reaction to cultures 72‐14‐5 (race 11‐32‐113, RPQ), 72‐41spl (race 15B, TLM), WM‐1 (race 18, LBC), Gb121 (race 121, DCM), 370c (race 151, QFL), Or9e (race 9, JBC), Orllc (race 151, QBC), 41‐21spl (race 15, TBC), 72.00 (race 11‐32‐113, RTQ), A‐1 (race 151, QSH), A‐5 (race 156, MBC; one F1 family), and 75‐86spl (race 151, QSH; one F1 family). One F1 family gave trigenic segregations with cultures WM‐1, Or9e, Orllc, 41‐21sp1, and A‐5. Data for reactions to culture A‐15 (race 17, HNQ) were a poor fit to a digenic ratio and were inconclusive; however, the data were a better fit to a digenic ratio than to a monogenic or trigenic ratio. Wdr‐sel had four genes for resistance to culture 111‐SS2 (race 111, LCB).

Paired comparisons of reactions to the different cultures were inconclusive but were consistent with the hypothesis that the gene for resistance to culture A‐14NW also conditioned resistance to the other cultures, and that the same two genes conditioned resistance to 13 of the cultures.
Phenotypic Stability Analyses of Sugarcane Cultivar Performance Tests1
Authors: Tai P.Y.P. , Rice E.R. , Chew V. , Miller J.D.
Published: July 2010

Estimation of the magnitude of cultivar‐environment interaction will provide information for developing more precise methods of selection. Cultivar trials of sugarcane (a complex interspecific hybrid of Saccharum spp.) in Florida were studied for cultivar × environment interaction and evaluated for the phenotypic stability by measuring regression coefficients (b) and mean square deviations from regression (S2d. Stalk weight, Brix, percent sucrose, percent purity, kilogram of sugar per metric ton of cane (S/T), metric tons of cane per hectare (TCH), and metric tons of sugar per hectare (TSH) were studied, with emphasis on Brix, S/T, TCH, and TSH. The variance component estimates for cultivars, cultivars × locations, cultivars × years were significantly different from zero. Linear regression analyses indicate that the current check did not have good stability for TCH and TSH and was not a stable standard for evaluating new selections. This analysis also demonstrated that some selections were superior to the check in TCH and TSH. However, for the three most important characters (S/T, TCH and TSH), none of the 10 selections ranked at the top for mean performance with good stability. This study suggests that stability analysis can provide supplementary information on the performance of new sugarcane selections prior to release for commercial cultivation and increase the efficiency of cultivar development programs.
Strain and Within‐Season Variability of Various Allelochemics Within A Diverse Group of Cottons1
Authors: White W. H. , Jenkins J. N. , Parrott W. L. , McCarty J. C. , Collum D. H. , Hedin P. A.
Published: July 2010

Several secondary plant metabolites are alleged to confer resistance of cotton, Gossypium hirsutum L., to various insects. The effects of these compounds on the insects, variability among cotton strains, and inheritance have been studied by various workers. Research on seasonal variability and on geotype × environment interactions is sparse. These findings prompted our research to determine the effects of within‐season environment and cotton strains on allelochemics alleged to be important in repelling the tobacco budworm, Heliothis virescens (F.).

Data were recorded on samples collected at 10 dates from 20 cotton strains in replicated field plots. The following allelochemics were quantified: total phenolics, gossypol and its analogs, a flavonoid‐anthocyanin mixture, and three tests for condensed tannins (tannin, El,l, and catechin). Significant differences among cotton strains, sample dates, and significant interaction between these main effects were detected. However, the interaction components were small relative to the main effects. These results suggest that differences in the levels of allelochemics are inherited and that genetic effects among cotton strains should be manageable in breeding programs.
A Comparison of Seed Quality and Seedling Vigor in Birdsfoot Trefoil
Authors: McKersie B.D. , Tomes D.T.
Published: July 2010

Seed quality, seedling vigor and field establishment were estimated in seed lots of three forage legumes, birdsfoot trefoil (Lotus corniculatus L.), alfalfa (Medicago sativa L.) and red clover (Trefolium pratense L.) in 1979 and in birdsfoot trefoil in 1980. Birdsfoot trefoil showed greater variability for germination than either red clover or alfalfa. Among 49 seed lots of birdsfoot trefoil tested in 2 years, 18 had less than 75% germination with a range of germination from 19 to 100%. Seed lots with poor germination generally had poor seedling vigor as measured by electrical conductivity, speed of germination and rate of seedling elongation. The maximal values of seedling vigor in birdsfoot trefoil were comparable to minimal values observed in alfalfa, except for electrical conductivity measurements which were similar between species. Quality measurements which were significantly correlated (p=0.01) with field establishment of birdsfoot trefoil (1980 data) were germination (r2=.66), electrical conductivity (r2=.59), speed of germination (r2=.66) and rate of seedling elongation (r2=.25). Seed weight was not significantly correlated with field establishment. Electrical conductivity had the highest correlation with establishment when measured after 24 hours soaking, compared to 1 and 6 hours soaking periods.

In seed lots of birdsfoot trefoil with over 75% germination, field establishment was still significantly different between lots. Some of this variability can be accounted for by differences among the cuitivars Leo, Empire, Maitland and Viking. For example, the cultivar Leo had superior speed of germination and field establishment compared to Empire. Seed size was not a reliable indicator of seedling vigor between seed lots of the same variety. Electrical conductivity was not reliable for comparisons among cultivars. Germination, speed of germination, seed size, electrical conductivity, and other unidentified factors contributed to successful field establishment, but the most limiting factor varied among seed lots. Thus, the prediction of a seed lot's field establishment based on only one measure of seed quality is tenuous.