bluuebunny/crossref_metadata_2025 huggingface dataset:
Introgression of the Glanded‐Plant and Glandless‐Seed Trait from Gossypium sturtianum Willis into Cultivated Upland Cotton Using Ovule Culture1
Authors: Altman D. W. , Stelly David M. , Kohel R. J.
Published: July 2010

Introgression of the glanded‐plant/glandless‐seed trait from Gossypium sturtianum Willis [2n = 2x = 26; C1 genome] into upland cotton, G. hirsutum L. [2n = 4x = 52; (AD)1 genomes] has not been successful using conventional hybridization techniques beyond the first backcross (BC1) pentaploid generation [2n = 5x = 65; genomic formula 2(AD)1C1]. Our main objective was to use ovule culture/embryo rescue to overcome this fertility barrier; secondary objectives were to determine if pairing would occur between the (AD)1 and C1 genomes and if the glanded‐plant/glandless‐seed trait would be expressed in other backcross generations. Pollination of BC1 plants in the field followed by ovule culture/embryo rescue produced 14 mature BC2 progeny with partial female fertility, demonstrating that tissue culture circumvented fertility barriers of the pentaploid interspecific hybrids. One BC2 had no glands while in culture, but was fully glanded after the first true leaf emerged. From this “glandless‐seed” plant, eight BC3 plants |2n = 55 or 57] and 125 BC4 plants have been derived. Five BC4 seed were completely glandless. Occurrence of trivalent chromosome associations indicated C1 chromatin was transferred in the backcross generations. The average rate of AAC and/or DDC trivalent formation was 5.16% for C1 chromosomes of BC1 to BC4 plants. Germplasm derived from this material could be important for developing cotton with higher levels of insect resistance and/or improved nutritional use.
Divergent Selecting for Ear Moisture in Early Maize1
Authors: Cross H. Z. , Chyle J. R. , Hammond J. J.
Published: July 2010

Two procedures to change ear drying rates were tested in five early maize (Zea mays L.) synthetics for their relative merits for breeding varieties adaptable to more timely harvest, which requires less grain drying and possession of acceptable agronomic characteristics. Objectives of this study were to assess the relative effectiveness of a laboratory and a field selection method for improving harvest moisture contents and to measure any correlated responses for other agronomic traits. Substrains in each synthetic, divergently selected for two or more cycles for relative rates of moisture loss from ears in the laboratory were evaluated in six environments along with substrains divergently selected for two cycles for ear moisture content at 45 days postpollination. Regression procedures were used to evaluate selection responses for ear moisture at harvest and correlated responses of other agronomic traits. Selection for slow relative moisture loss in the laboratory (SD) changed field harvest moisture by −6.73 g kg−1 cycle−1 and produced correlated reductions in ear length, kernels per ear, kernel rows per ear, ear weight, and root lodging. Selection for low ear moisture at 45 days postpollination (LM) changed harvest ear moisture in selected strains by −7.15 g kg−1 cycle−1. Correlated increases in test weight and decreases in stalk lodging also were observed. Selection for fast relative moisture loss in the laboratory (FD) or high moisture content at 45 days postpollination (HM) generally produced increased ear moisture at harvest in selected strains. Neither yield nor silking dates were changed by the selection methods. Harvest moisture responses from the SD method seemingly resulted from reduced moisture content at 45 days postpollination rather than changes in the rate of moisture loss from the ear. Whether selection has produced basic changes in endosperm composition remains to be determined. The LM method appears very feasible for practical breeding programs because of simplicity and effectiveness
Genetic Control of High Oleic Acid Content in Sunflower Oil1
Authors: Miller J. F. , Zimmerman D. C. , Vick B. A.
Published: July 2010

Sunflower (Helianthm annuus L.) oil high in oleic fatty acid composition is less susceptible to oxidative changes during refining, storage, and frying; therefore, quality is retained longer than sunflower oil high in linoleic fatty acid in both processed oil and the seed. Objectives of this study were to: (i) determine if oleic content of sunflower oil was maternally influenced, (ii) determine the genetic control of oleic acid content, and (iii) identify any modifying factors influencing high oleic acid content. High oleic lines of sunflower derived from ‘Pervenets’ were crossed with the low oleic inbred line, HA 89. The F1 seed was intermediate in oleic acid content with reciprocal crosses showing maternal effects. This maternal effect on oleic acid is important in determining isolation of both hybrid seed production and general field production of high oleic acid and high linoleic acid sunflower. Oleic acid content was controlled by a major gene with partially dominant gene action, Ol, and a second gene, designated ml. When the recessive gene, ml, is present in homozygous condition, and combined with the gene Ol, oleic levels in seed were elevated to 820 g kg−1 of oil or higher. The linear correlation coefficient between linoleic and oleic acid content for seed analyzed was −0.84, indicating that linoleic and oleic were the fatty acids primarily affected. For expression of very high oleic content in a sunflower hybrid grown in the north central states of the USA, a dominant allele of the Ol gene and the recessive alleles, mlml, of the Ml gene will be necessary.
In Vitro Digestibility of Dry Matter and Cell Wall Constituents of Smooth Bromegrass Forage1
Authors: Casler M. D.
Published: July 2010

The availability of forage cell walls to ruminants is dependent on the concentration and digestibility of cell wall constituents. The objectives of this study were to quantify genotypic variation for in vitro digestibility of individual cell wall constituents and relate this variation to variation in concentration of cell wall constituents of smooth bromegrass (Bromus inermis Leyss.). Eighteen clones were grown at Arlington, WI, and sampled in 1982 and 1984. Forage samples were harvested to simulate a normal first cutting. Samples were analyzed for cell wall constituents of dried forage and forage that had been previously digested by rumen microorganisms. In vitro digestibility (IVD) of cell wall constituents was computed from differences obtained between undigested and digested forage samples. Genotypic variation was significant for IVD of neutral detergent and acid detergent fiber (NDF and ADF, respectively), cellulose, and hemicellulose, but not for acid detergent lignin (ADL). In vitro digestibilities of dry matter, NDF, ADF, cellulose, and hemicellulose were mutually correlated, with r ≥ 0.87. Concentration and IVD of cell wall constituents generally were not correlated, with ‒0.52 ≤ r ≤ 0.22. Selection for divergent IVD of dry matter (IVDMD) resulted in similar changes to IVD of NDF, ADF, cellulose, and hemicellulose; differences between high and low IVDMD clone groups ranged from 37 to 42 g kg−1 for IVD of cell wall constituents. The additional information provided by determining IVD of cell wall constituents makes these selection criteria potentially valuable. Because of their close interrelationships and similar correlated selection responses, IVD of NDF, which is the easiest and least expensive to determine, would satisfactorily represent the other IVD variables in smooth bromegrass.
Modification of Methods for Identifying Inbred Lines Useful for Improving Parents of Elite Single Crosses1
Authors: Dudley J. W.
Published: July 2010

In many hybrid breeding programs, corn (Zea mays L.) programs for example, a common practice is to cross one inbred parent (e.g., I1) of an elite hybrid (I1 ✕ I2) to a donor inbred (Iw) and attempt to isolate a new line with improved performance in crosses to I2. for Iw to be useful as a donor of alleles for improving I1 ✕ I2, Iw must contain favorable alleles at loci (class G loci) for which I1 ✕ I2 is homozygous unfavorable. A previous method for identifying such lines assumed that the number of loci for which I1, I2, and Iw were all homozygous favorable (class A loci) was equal to the number for which all three lines were homozygous unfavorable (class H loci). In addition, genotypic values of μ, μ, and —μ instead of the more general z + 2μ, z + μ + aμ, and z were assigned to + +, + ‒, and ‒ ‒ genotypes, respectively, where μ is one‐half the difference between homozygotes, a is a measure of degree of dominance, and z is the value of the ‒ ‒ genotype. The previous method was modified to identify donor inbreds without the assumptions that Z = ‒μ and that μA = μH. A new set of estimation equations is presented and the effect of relaxing the assumption of complete dominance is described. Based on the new set of equations, I2 lines would not need to be evaluated if information on class B loci (those for which I1 and I2 are + + and Iw is ‒‒) is not needed. Use of the new estimators is illustrated by applying them to a set of corn data. Results from the modified method are in closer agreement with expectations based on pedigrees and experience with the lines involved than were results using the original methods.
Growth and Yield of Barley Isopopulations Differing in Solute Potential1
Authors: Grumet Rebecca , Albrechtsen Rulon S. , Hanson Andrew D.
Published: July 2010

The active accumulation of solutes by osmotically stressed plants is thought to be an adaptive response that increases the ability of drought‐ or salt‐stressed plants to maintain leaf water content, turgor, and possibly growth. In an earlier study we developed two barley (Hordeum vulgare L.) isopopulations differing in solute potential (ψs), and these isopopulations were characterized for their response to salt stress in the growth chamber. At each stress level tested, the low‐ψs population had about 0.1 MPa lower ψs. In the present study we used these isopopulations to test the effect of genetic differences in ψs on growth in well‐watered and drought‐stressed conditions in the greenhouse and field. When grown in the greenhouse, the low ψs population had a slower rate of leaf production and accumulated significantly less total aboveground dry matter by midanthesis than did the high‐ψs population. This difference (up to 35%) was greatest in optimal environmental conditions (adequate water, high irradiance, warm temperatures) and decreased in less favorable environments. The growth differences were not associated with differences in partitioning of dry matter to the leaves or differences in water use efficiency. The growth disadvantage of the low‐ψs population was also observed for grain yield (11–44%) and total aboveground biomass production (10–25%) under dryland and irrigated conditions in multisite field trials. Thus the development of a barley isopopulation with constitutively lower ψs resulted in a reduction in yield potential.
Carbon Isotope Discrimination is Positively Correlated with Grain Yield and Dry Matter Production in Field‐Grown Wheat1
Authors: Condon A. G. , Richards R. A. , Farquhar G. D.
Published: July 2010

Carbon isotope discrimination (Δ) is a measure of the ratio of the intercellular and atmospheric partial pressures of CO2. Variation in Δ within some C3 species, including wheat (Triticum aestivum L.), has recently been correlated with variation in water use efficiency of droughted plants grown in the glasshouse. The objectives of this study were to assess genotypic variation in a larger group of wheat genotypes grown at three locations, and to determine the relationship between yield of field‐grown plants and Δ when water was not a limitation to growth. Twenty‐four bread wheat genotypes, one durum (Triticum turgidum L. durum), and two triticale genotypes (x Triticosecale rimpaui Wittm.) were grown in replicated plots at two locations in southern New South Wales, Australia, in 1984. The growing season had above average rainfall, especially in the period preceding antbesis. Carbon isotope discrimination was measured on stem material for each plot. Final aboveground biological yield and grain yield were also measured. There was substantial genotypic variation in Δ. Genotypic ranking for Δ was consistent across field sites and between field‐grown plants and plants grown in pots at another location. A potential source of variation in Δ is variation in stomatal conductance. For pot‐grown plants, the relationship between Δ and total leaf conductance was poor. However, Δ and conductance of the abaxial leaf surface were positively correlated. Under field conditions of nonlimiting water, biological yield and grain yield were both positively correlated with Δ. This latter result indicates that carbon isotope discrimination may be used to select for increased yield in wheat.
Stability in Yield and Fiber Quality of California Cotton1
Authors: Geng Shu , Zhang Qifa , Bassett D. M.
Published: July 2010

Stable performances in crop yield and quality traits over a wide range of growing conditions are desiralbe from a standpoint of management and marketing. In this paper, we have studied the stability of yield and quality of 43 cotton (Gossypium hirsutum L.) cultivars tested in California cotton breeding programs over 18 yr (1966–1983). There is a positive correlation between mean yield and the stability coefficient for yield. This association suggests that cotton cultivars producing higher yields are, in general, lower in stability. Exceptions, however, are observed in a few cultivars, suggesting that selection for specific adaptation does not automatically lead to reduction in general adaptability. Quality scores are less responsive to environmental changes than yields. Still, a negative correlation between mean quality scores and stability coefficients of fiber qualities is observed. Thus, changes brought about by plant breeding have resulted in progressive changes in the direction of higher quality and greater stability of quality. Our analysis shows that plant breeding in the last 18 yr has simultaneously improved yield and quality in California cotton, and that future selections for new cultivars with emphasis on quality may result in greater economic returns.
Injury and Yield Response of Soybean to Chronic Doses of Ozone and Soil Moisture Deficit1
Authors: Heagle Allen S. , Flagler Richard B. , Patterson Robert P. , Lesser Virginia M. , Shafer Steven R. , Heck Walter W.
Published: July 2010

A 2‐yr field study was performed near Raleigh, NC, to determine injury and yield response of soybean [Glycine max (L.) Merr. ‘Davis’] to long‐term O3 exposure and soil moisture deficit. Two levels of soil moisture [well‐watered (WW) and water‐stressed (WS)] were tained by differential irrigating during periods of low precipitation. Open‐top field chambers were used to expose plants to different levels of O3 for 109 days. The 1983 season was drier and hotter than the 1984 season. In 1983, plants in the WS plots were under moderate to severe moisture stress from shortly after planting (V2) until midway through flowering (R3) and they yielded approximately half as much as those in the WW plots. In 1984, plants in the WS plots were under moderate moisture stress during flowering and pod‐fill stages and they yielded 20% less than those in the WW plots. In 1983, there was a significant relationship between O3 concentration and yield in the WW plots, but not in the WS plots. In 1984, similar linear responses to O3 occurred at both levels of soil moisture. Compared to yield in the charcoal‐filtered‐air (control) treatment (2‐yr 7 h day−1 mean O3 concentration of 0.027 μL L−1), predicted yield loss for WW plots at ambient O3 levels (2‐yr 7 h day−1 mean of 0.054 μL L−1) was 12% in 1983 and 14% in 1984. The predicted loss value for the WS plants in 1984 was 12%.
Effects of Soybean Seed Size, Vigor, and Maturity on Crop Performance in Row and Hill Plots1
Authors: Tekrony D. M. , Bustamam T. , Egli D. B. , Pfeiffer T. W.
Published: July 2010

Soybean [Glycine max [L.] Merr.] seed size (mg seed−1) has been shown to vary considerably within and among seed lots. This investigation was conducted to determine the effect of seed size and vigor on crop performance when planted in hill and row plots. Seed lots of mature and immature seed (‘DeSoto’) were selected to have a range in seed size (68‐212 mg seed−1) and seed vigor (low to high) but acceptable standard germination (> 82%). These seed lots were evaluated for crop performance in two field experiments: bordered row plots (1983–1985) and unbordered hill plots (1984,1985). Near ideal soil conditions at planting resulted in excellent field emergence, and adequate plant populations occurred for all seed lots in both field experiments. Field emergence was significantly correlated with seed vigor, but showed little relationship to seed size. Both seed size and vigor positively influenced plant height at growth stages R2 and R7. Seed yield (kg ha>) of row plots was not significantly related to seed size or vigor in the 3 yr evaluated. Yields in row plots were similar across a wide range in seed size and vigor even for immature seed lots harvested prior to physiological maturity (growth stage R7). In hill plots, the seed yield (g plot 1) was significantly related to both seed size and vigor with lower yields occurring for seed lots with low vigor and with smaller size (< 100 mg seed−1). This yield response in hill plots was especially evident for immature seed lots; therefore, precautions should be taken to evaluate seed lots for seed size and vigor before testing in unbordered hill plots.
Plant Traits Related to Productivity of Maize. I. Genetic Variability, Environmental Variation, and Correlation with Grain Yield and Stalk Lodging1
Authors: Willman M. R. , Below F. E. , Lambert R. J. , Howey A. E. , Mies D. W.
Published: July 2010

Numerous physiological traits act and interact with each other and the environment to determine maize (Zea mays L.) grain yield and stalk lodging. Plant breeders need to know the most important traits on which to concentrate breeding efforts. Our objectives were to: (i) evaluate genotypic variation and effect of environment on 21 plant traits measured on 76 maize hybrids representing four maturity groups; and (ii) determine the relationship of these traits to grain yield and stalk lodging. The four groups were evaluated separately at several locations for grain yield and stalk lodging in 1984 and at single locations in 1984 and 1985 for plant traits. This investigation reports on an extensive evaluation and comparison of individual traits related to grain yield and stalk lodging in maize. For all groups, significant variation among hybrids was observed for most traits when analyzed over 2 yr. From six to nine traits in each group exhibited significant hybrid ✕ year interaction. However, 13 of 21 traits exhibited significant hybrid ✕ year interaction in at least one of the four groups. Evaluation of phenotypic correlations indicated none of the plant traits was significantly and consistently correlated with grain yield or stalk lodging over the four groups. The correlation between a given trait and grain yield or stalk lodging was affected by relative maturity and hybrid genotype, as well as the environment. These results indicate the relationship between plant traits and productivity is complex and that the use of a single plant trait in a breeding program would likely be ineffective in improving grain yield and/or stalk lodging resistance of maize
Effects of the Sugary‐1 Locus on Plant and Ear Traits in Corn1
Authors: Hunsperger M. H. , Davis D. W.
Published: July 2010

Attempts to use dent corn (Zea mays L.) to improve sugary‐1 (su) sweet corn have not been widely successful due to difficulty with the simultaneous recovery of traits being transferred and acceptable quality. The lack of success may be caused by linkage, pleiotropy of the su gene, inadequate recombination before initiating selection, or insufficient population size. The objective of this study was determine if the su allele affects 19 important sweet corn traits. Plants from starchy (Su) and sugary (su) So seed of a dent ✕ sugary composite were grown in four environments at 36 900, 57 400, and 73 800 plants ha−1, with ear measurements recorded at milk‐stage maturity. The Su and su S1 progenies were grown in two environments at 51 700 plants ha−1, with data taken on mature dried ears. Sugary So segregates demonstrated a greater tendency toward delayed maturity and lodging than Su segregates. Tip blanking was reduced in su So and S1 plants. Ear length was reduced in su So plants and Susu plants from Su‐‐S1 ears. Plant endosperm type had no effect on percent marketable ears or yield among So segregates, or on S1 ear diameter, taper, and curvature. The su gene effects provide some explanation for the difficulty encountered when using dent corn in sweet corn improvement, but were not so pronounced as to be insurmountable in a breeding program.
Soybean Leaf Photosynthetic Response to Changing Sink Demand1
Authors: Lauer Michael J. , Shibles Richard
Published: July 2010

To determine the extent to which photosynthesis of mature and immature soybean [Glycine max (L.) Merr.] leaves would respond to change in reproductive sink demand, plants were treated to enhance and diminish sink size. Thinning the stand at R3 induced greater pod set and an increase in pod growth rate of the remaining plants, whereas continuous partial depodding (leaving one pod to develop at each mainstem node) reduced pod growth rate by 65%. Thinning the stand resulted in maintenance of peak protein and photosynthetic rate in fully expanded (node 7) leaves of the remaining plants, whereas shortly after reaching maximum these activities declined by about 20% in controls. In expanding (node 10) leaves, thinning increased protein and photosynthetic rate about 20% compared with controls. Partial depodding had no effect on leaf photosynthetic rate, but did result in failure of protein to be mobilized to sinks. The response of fully expanded leaves as well as expanding leaves to increased sink size indicates that a source leaf can respond photosynthetically to changes in sink demand even after reaching full growth. That greater than normal sink size stimulated more rapid photosynthesis suggests that the soybean leaf possesses unrealized photosynthetic capacity. As a corollary, it may be concluded that factors determining pod retention are more limiting to yield in this species than is photosynthesis.
Frequency and Comparative Anatomy of the Extended Endothelium among Soybean Plant Introductions and Weathering Resistant Genotypes1
Authors: Baker Daniel M. , Minor Harry C.
Published: July 2010

In some genotypes of soybean [“Glycine max” (L.) Merr.], the endothelium of the testa forms a dome‐shaped extension in the region of the pit in the abaxial surface of the cotyledons. The importance and functions of this tissue are not fully understood. Using scanning electron microscopy we observed a high frequency (0.91) of the extended endothelium in experimental weathering resistant genotypes received from the International Institute of Tropical Agriculture. Similar examination of 378 random genotypes from the USDA soybean germplasm collection revealed the frequency of this trait to be 0.34. The dimensions of this tissue in these latter genotypes varied from <0.4 to >2.1 mm2 in area, and from 80 to 220 pm in thickness. The cells of the extended endothelium are generally large, vertically elongated, and have large cell wall thickenings.
Quadratic Components of Covariance of Inbred Relatives and Their Estimation in Naturally Self‐Pollinated Species
Authors: Cornelius P. L. , Van Sanford D. A.
Published: July 2010

Several expressions for the covariances of inbred relatives, under assumptions of equilibrium genotypic frequencies in the initial population, no linkage and no epistasis, have been presented in the literature. These expressions in multiple‐allelic cases involve five quadratic components that must be estimated if certain genetic variances and covariances are to be estimated. Four of the five components in one parameterization, the D‐model, are involved in a linear dependency and, therefore, nonestimable in experiments in which only selfed progenies are evaluated. If all five components are to be estimated in a self‐pollinated species, selfed progeny must be augmented with crossed progeny or with selfed progeny derived from crosses among individuals in the base population. A mating scheme that could be implemented with a minimum of crossing in a selfpollinated species is proposed, along with formulas for the covariances of relatives involved. Two alternative parameterizations, the C‐model and Q‐model, are considered. In the C‐model σ2A and σ2D are not estimable, but the total genetic variance at panmixia σ2G0 = σ2A + σ2Dis estimable. The Q‐model, derived by subdividing σ2A into three particular functions of contrasts of genotypic values, allows three subcomponents of σ2G0 to be estimated. The models reduced to four parameters are adequate if only covariances of relatives under self‐fertilization need to be estimated, but reduction to four parameters is neither adequate nor possible under some other inbreeding system, mixture of inbreeding systems, or mixture of selfing and crossing.
Combining Ability Differences between Isogenic Diploid and Tetraploid Alfalfa
Authors: Groose R. W. , Kojis W. P. , Bingham E. T.
Published: July 2010

A principal advantage of reducing polyploid crops for breeding at the diploid level (analytic breeding) is that inheritance is simpler and more intense selection might be applied for some traits at the diploid level. The polyploid would then be resynthesized from selected diploids. Analytic breeding has been used to effectively manipulate genes that condition several qualitative traits in autotetraploid alfalfa (Medicago sativa L.). This study was designed to compare the relative merit at the diploid and tetraploid levels of genes that contribute to important quantitative traits of alfalfa. Isogenic diploid and tetraploid clones of alfalfa were produced by colchicine doubling five clones of cultivated alfalfa at the diploid level (CADL). A sixth CADL clone produced n and 2n pollen and was used as both a diploid and tetraploid parent. The CADL clones varied in the number of diploid generations in their background from one to six generations. The six clones were mated in diallel at the diploid and tetraploid levels to evaluate combining ability. Single cross families were evaluated for forage yield and fertility at each ploidy level. Neither single cross family means nor general combining abilities were positively correlated between ploidy levels. A genotype that was the poorest parent at the diploid level was the best parent at the tetraploid level. In summary, a diallel analysis at the diploid level failed to predict performance at the tetraploid level. Selection of diploid genotypes for use at the tetraploid level would be undesirable in this set of materials.
Performance and Use of Seedcoat Mutants in Soybean
Authors: Wilcox J. R.
Published: July 2010

Soybean [Glycine max (L.) Merr.) mutants with solid (i) or saddleshaped (/k) seedcoat color patterns occur as the result of natural mutations at the I locus. These mutant isolines may be useful in determining effects of environmental factors, such as diseases, on resistance genes that could be backcrossed into one of the isolines. Prior to such uses, the productivity of the isolines would have to be determined. The first objective of this study was to evaluate the agronomic performance of seedcoat mutants in several cultivars in comparison with the normal (ii) isoline. A second objective was to determine the frequency of these in harvested seed from 1:1 blends with the normal isolines. Normal and mutant seedcoat isolines of six maturity Group II and III cultivars and blends of the two isolines were evaluated for 2 years in four‐replicate tests at Lafayette, IN. In a second test, performance of ii, ik, and i isolines of ‘lCentury’ were evaluated for 2 years at the same location. There were no differences in seedling emergence, maturity date, lodging, mature plant height, or seed yield among isolines of the differnet cultivars except for a 9% difference in seedling emergence for one cultivar and a 1‐ and 2‐day difference in maturity date for two cultivars in these tests. The 2‐year average frequency of normal seeds in the blends varied from 51 to 53% based on a 400‐seed count of harvested seed from each replication. Chi‐square analyses of the frequency of normal and mutant seeds harvested from the blends indicated a significantly higher reproductive rate for the ii than for the i allele. The use of seedcoat mutants to study effects of environmental factors, such as diseases, on isolines of specific cultivars was discussed.
Selection for Improved Sugarbeet Storability
Authors: Campbell L. G. , Bugbee W. M.
Published: July 2010

Previous research has indicated the feasibility of selecting for improved sugarbeet (Beta vulgaris L.) postharvest storability but has not produced parental lines suitable for hybrid production. Germplasm possessing multiple traits for improved storability would facilitate the development of commercial hybrids with improved storability characteristics. This article reports the progress after four cycles of selection for combined low storage‐respiration (low internal CO2 concentration) and resistance to three prevalent storage‐rot fungi, Phoma betae (Oud.) Frank, Botrytis cinerea Pets. ex Ft., and Penicillium claviforme Bainier. Field‐grown roots stored for 60 d at 5°C were evaluated. The fourth cycle of selection produced families with an average internal CO2 concentration 27% below the average of the check hybrids. The average rot index of the selected families was 53% of the checks. Eight of 65 families had significantly lower internal CO2 levels combined with significantly lower rot ratings than the checks for at least two of the three fungi. Three of these families had combined low internal CO2 levels and low ratings for all three storage‐rot fungi. The results indicated that desired storability traits can be combined in individual lines. Negative relationships between storability traits and root yield and quality were of minor importance, indicating that improved storability need not imply a compromise in agronomic performance.
Inheritance of Chlorimuron Ethyl Sensitivity in the Soybean Strains BSR 101 and M74‐462
Authors: Pomeranke G. J. , Nickell C. D.
Published: July 2010

Initial work with the sulfonylurea herbicide chiorimuron ethyl (ethyl 2‐[[[[(4‐chloro‐6‐methoxypyrimidin‐2‐yl) amino] carbonyl] amino] sulfonyl] benzoate) indicated that certain soybean [Glycine max (L.) Merr.] strains exhibited high levels of sensitivity to recommended field application rates. Knowledge of the mode of inheritance of chiorimuron ethyl sensitivity would allow for generation of cultivars toleranto chlorimuron ethyl. In addition, cross tolerance to other members of the suifonylureas has been observed and tolerance to chlorimuron ethyl may be expressed as tolerance to other sulfonylureas. Sensitive and tolerant strains of soybean were identified and two crosses of a tolerant strain ‘Elgin’ by the sensitive strains ‘BSR 101’ and M74‐462 were evaluated in the F2 and F3 generations to determine the mode of inheritance of chlorimuron ethyl sensitivity. The F2 plants and F2‐derived families in the F3 generation from each of the crosses were evaluated in the greenhouse using a hydroponic culture. Three days after transplanting seedlings into Hoagland's solution, chlorimnron ethyl was added giving a concentration of 2 mg a.i. L−1. Ten days after treatment, the plants were rated based upon reddening of the leaves. This evaluation indicated that chlorimuron ethyl sensitivity in both BSR 101 and M74‐462 is conferred by a single recessive gene.
Combining Ability of High Lysine Sorghum Lines Derived from P‐721 Opaque
Authors: Monyo E. S. , Ejeta G. , Nyquist W. E. , Axtell J. D.
Published: July 2010

The P‐721 opaque (P‐721Q) endosperm of sorghum [Sorghum bicolor (L.) Moenchl has better protein quality (lysine/protein ratio) than normal sorghum endosperms. However, sorghum with opaque endosperm has not been readily accepted for wide cultivation due to its lower yield potential and some other problems associated with its soft endosperm. The objective of this study was to determine whether hybrids between high yielding opaque lines resulted in heterotic response for grain yield and kernel weight without loss in protein quality. Each of 10 high lysine lines derived from P‐721Q was mated with the same three cytoplasmic male‐sterile lines, also derived from P‐721Q by backcrossing to sterile cytoplasm. The F1 hybrids derived from these matings were field‐evaluated for grain yield, 100‐kernel weight, protein concentration, and lysine concentration in protein on a fine‐silty, mixed, mesic Typic Haplaquoll. Significant differences among general combining ability effects were observed for all characters except grain yield, whereas significant differences among specific combining ability effects were observed for only grain yield. Correlation between grain yield and protein in the 30 hybrids was negative and significant (r = −0.63); correlation between grain yield and lysine concentration in protein was also negative but not significant. The best male parent, R‐3 (P‐850314), also produced hybrids with the highest lysine concentration. Among the female parents, A‐3 (P‐851063) gave hybrids with the highest protein quality. The best single‐cross hybrid, A‐3 ✕ R‐3, for agronomic and protein quality, had 35% more lysine than the normal cultivar P‐721N and yielded as much as the NK‐180 check. Thus, this hybrid has the potential of substituting for other expensive protein and lyslne sources in the semiarid tropics.
Near Infrared Reflectance Spectroscopy Evaluation of Ruminal Fermentation and Cellulase Digestion of Diverse Forages
Authors: Marten G. C. , Halgerson J. L. , Sleper D. A.
Published: July 2010

Digestible dry matter determined by in vitro rumen fermentation (IVDDM) is recognized as a superior assay of digestible energy potential of forages, but fungal ceilulase digestion (NDSCS) can a less costly substitute. Our primary objective was to ascertain the relationship between the two methods and whether near infrared reflectance spectroscopy (NIRS) could be used to estimate in vitro digestibility of diverse forages by either method. We also wanted to compare wavelength selection during equation development by NIRS. We analyzed 499 samples among five diverse cultivated forage and weed groups. Digestibility determined by the two in vitro methods was highly correlated; r ranged from 0.98 to 0.83. The NDSCS method provided more complete digestion than IVDDM for all forage groups. The NIRS calibration equations for both methods had coefficients of determination (R2) of 0.86 to 0.97 for four of the five groups. The R2 values were higher and the standard errors of analysis (SEA) were lower for IVDDM (SEA of 7.2‐31.1 g kg‐1) compared with NDSCS (SEA of 11.8‐38.9 g kg‐1). Biases were negligible. Ten of 46 wavelengths used were identical for the best IVDDM and NDSCS equations, and 26 wavelengths were within 20 nm of being identical. Eleven peaks or valleys of the mean NIR spectra for the 499 samples were at or near wavelengths known to be absorbed by feed nutrients or fiber fractions. We conclude that the IVDDM and NDSCS methods usually similarly ranked cultivated forages or weeds for in vitro digestibility and that NIRS can estimate digestibility by either in vitro method. Wavelength selection during NIRS equation development appears to be based on chemical entities that are often commonly digested by rumen microorganisms and cultured cellulase.
Kentucky Bluegrass Automatic Hybridization Apparatus
Authors: Riordan T. P. , Shearman R. C. , Watkins J. E. , Behling J. P.
Published: July 2010

Kentucky bluegrass (Poa pratensis L.) is a major turfgrass species of the cool, humid region of the USA. Breeding improvement has been hampered because of its high percentage of apomictic seed production and an anthesis time that occurs during the middle of the night. In an effort to produce larger number of hybrids, an automatic hybridization apparatus was developed to facilitate Kentucky bluegrass hybridization. The apparatus was built from easily obtained materials and was designed to allow (i) suspension of one plant above another, (ii) environmental modification of the lower plant, (iii) control of pollen dispersal, (iv) a moderately large number of different crosses to be attempted, and (v) easy set‐up and dependability. When compared with hand pollination this automatic hybridization apparatus gave a lower percentage of hybrids, but was more efficient in total number of hybrid plants produced.
Comparative Turfgrass Evapotranspiration Rates and Associated Plant Morphological Characteristics
Authors: Kim K. S. , Beard J. B.
Published: July 2010

Since water costs are projected to increase substantially, and water availability for turfgrass culture will become more limiting, there is a need for a detailed characterization of water use rates among turfgrass species. The evapotranspiration (ET) rates of 11 C‐4 warm‐season turfgrasses and one C‐3 cool‐season turfgrass were evaluated in minilysimeters with fritted clay as the rooting medium utilizing the water balance method. Turf plots of 1.5 × 1.5 m were constructed to ensure a natural environment surrounding each lysimeter. Evapotranspiration rates plus six morphological characteristics of each species were measured under nonlimiting soil moisture. Significant differences in ET rates were observed both among and within genera. ‘Texas Common’ buffalograss [Buchloe dactyloides (Nutt.) Engelm], ‘Georgia Common’ centipedegrass [Eremochloa ophiuroides (Munro.) Hack], ‘Arizona Common’ bermudagrass [Cynodon dactylon (L.) Pers.], ‘Tifgreen’ and ‘Tifway’ bermudagrasses [C. dactylon (L.) Pers. × C. transvaalensis Davy], and ‘Adalayd’ seashore paspalum (Paspalum vaginatum Sw.) had low ET rates; while ‘Emerald’ zoysiagrass (Zoysia japonica Steud. × Z. tenuifolia Willd. ex Trin.) was characterized as having a medium ET rate. ‘Texas Common’ St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] and ‘Meyer’ zoysiagrass (Z. japonica Steud.) possessed medium low ET rates. However, a 1‐yr study showed that ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.) and ‘Argentine’ bahiagrass (Paspalum notatum Flugg.) had medium ET rates, and ‘Common’ blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] possessed a medium low ET rate. Those grasses with comparatively lower ET rates were generally characterized by (i) a high canopy resistance, including a high shoot density and relatively horizontal leaf orientation; and (ii) a low leaf area, including a slow vertical leaf extension rate and a narrow leaf texture.
Prediction of Cell Wall Carbohydrates and Quality in Panicum Species by Near Infrared Reflectance Spectroscopy
Authors: de Ruiter J. M. , Burns J. C. , McClure W. F. , Timothy D. H.
Published: July 2010

The composition of forage plant cell walls alters the rate and extent of dry matter digestion. A rapid, nondestructive method of analysis that avoids constituent rearrangements and artifact formation would aid the ease and accuracy of determining the structural carbohydrates (SC). This study evaluated the use of near infrared reflectance spectroscopy (NIRS) for predicting the SC fractions and constituent carbohydrate monomers the cell walls of whole and separated plant parts of subtropical grasses. Two accessions representing a high and low in vitro dry matter disappearance (IVDMD) were selected from within three Panicum taxa [Panicum amarum Elliot var. amarum, P. amarum var. amarulum (Hitch. and Chase) P.G. Palmer, and P. virgatum L.] that had been classified morphologically into tall (hay), intermediate, and short (grazing) categories. Variation occurred in SC duet o morphology, maturity, plant part (leaf blade, leaf sheath, and stem) and in IVDMD. Cell wall xylose from trifluoroacetic acid hydrolysis was predicted by NIRS with relative accuracy (R2 = 0.91 for calibration, r = 0.88 for prediction) and with standard errors for calibration and analysis of 10.2 and 15.9 g kg−1, respectively. Predicted values for cell wall xylose concentrations of equivalent samples (n = 30) from two successive years compared very closely, with only small changes in relative ranking between years (r = 0.92). Similar results were noted for arabinose (r = 0.78), galactose (r = 0.80), glucose (r = 0.79), and quality variables such as IVDMD, neutral detergent fiber, and acid detergent fiber (r = 0.91). Composition of cell walls using NIRS technology may provide a physiological base for the genetic improvement of low quality forage grasses, especially the xylose concentration, which is known to be inversely related to IVDMD.
Prediction of Percentage Leaf in Stratified Canopies of Alfalfa with Near Infrared Reflectance Spectroscopy
Authors: Hill N. S. , Petersen J. C. , Stuedemann J. A. , Barton F. E.
Published: July 2010

Because digestibility is maintained with leaf but declines with stem age, study of the plant‐animal interface may yield information regarding grazing management options for legume based pastures. Current methods used to analyze esophageal samples for dietary components are time consuming and inherent with human error. The objectives of this study were to determine if percentage leaf could be predicted by near infrared reflectance spectroscopy (NIRS) and if predictions were affected by cultivar differences or addition of saliva to artificially mixed samples of alfalfa (Medicago sativa L.). Two genetically diverse cultivars, ‘Apollo’ and ‘Florida‐77’, were hand‐clipped from field plots at the 1/10 bloom stage throughout the 1986 growing season. Harvested plants were separated into top, middle, and bottom strata and the leaves and stems separated. Bovine (Bos taurus) saliva was added to half of each of the leaf and stem fractions, masticated with a mortar and pestle, and the samples freeze‐dried and ground. Artificial sample sets varying in percent leaf and stem were used to establish NIRS calibration equations. Coefficients of multiple determinations for calibration (R2) and coefficients of determination for prediction (r2) were 0.96 and 0.93 or better, respectively, and standard errors of calibration and prediction were 5.60 and 7.41 or lower, respectively, among successful calibration equations. Calibration of NIRS with Fla‐77 samples failed when used to predict the Apollo set. We conclude that NIRS is a rapid and accurate method to determine percentage leaf in alfalfa, and solids in saliva had no effect on light reflectance at the selected wavelengths.
Effect of Early Defoliation on Maize Growth and Yield: an Eleven‐year Perspective
Authors: Crookston R. Kent , Hicks Dale R.
Published: July 2010

We previously reported that grain yield of the maize (Zea mays L.) hybrid ‘Trojan TXS 85’ was increased following 100% defoliation at the five‐leaf stage. The objective of this study was to extend those observations and to examine the relationship between early defoliation, soil‐water use, and yield. Eight additional years of defoliation trials (plants 100% defoliated at the five‐leaf stage) were conducted in the field with Trojan TXS 85. The soils at the two experimental sites are a Webster clay loam (Typic Haplaquoll) and a Nicollet clay loam (Aquic Hapludoll). Defoliation decreased grain yield 3 of the 8 additional yr, and had a nonsignificant (negative) effect the remaining 5 yr. Positive yield response to defoliation was associated with low yields and with low end‐of‐season available soil water. It thus appears that an early reduction in vegetative growth of maize might help avoid drought stress in regions where late‐season water stress is common. Early defoliation does not appear to be a practical management approach in high‐yielding environments, such as the upper Midwest, where soil‐water deficits are infrequent and unpredictable.
Influence of Sugarcane Mosaic Virus on Segregation for Two Seedling Characteristics in Sorghum
Authors: Stokes I. E. , Mock R. G. , Gillaspie A. G.
Published: July 2010

Sorghum (Sorghum bicolor L., Moench) yields are reduced in many areas by the sugarcane mosaic virus. Losses from pathological effects of the virus have been documented; information about genetic effects could lead to improved production practices and more efficient breeding programs. Our objectives were to determine whether the sugarcane mosaic virus strain A (SCMV‐A) in one of the parent plants of a sorghum cross could influence segregation for seedling color and ligule expression in later generations, and whether segregation of this type could be detected and evaluated by phenotypic observations. In tests under greenhouse conditions, deviations in segregation of four phenotypes in F2 populations of reciprocal control crosses were not significant. Segregation of F2 plants into four phenotypes in control and treated (T) (one virus‐infected parent) populations was significantly different from expected ratios in the cross ‘Planter’ (T) × ‘MN4611’, at the 5% level, and at the 1% level in Planter × MN 4611 (T). Deviations in distribution of nine F2 genotypes within treated populations, observed in F3 seedlings, of the cross Planter × MN 4611, were significant at the 5% level and in MN 4611 × Planter at the 1% level. Also, deviations in distribution of F2 genotypes from expected ratios in populations from control and treated crosses, were significant at the 1% level in MN 4611 × Planter. Although SCMV‐A in one of the parent plants did not produce recognizable virus symptoms in F1, F2, or F3 populations; it was associated with deviations of F2 genotypes from expected ratios.
Evaluation of Maize Populations as Sources of Favorable Alleles
Authors: Dudley J. W.
Published: July 2010

Choice of populations to use in improving elite maize (Zea mays L.) hybrids is a critical decision in maize breeding programs. Nineteen maize populations were evaluated for their potential as sources of alleles to improve the hybrid FRB73 × FRMo17 for grain yield, ear height, flowering date, stalk lodging, and root lodging. The populations BS11(FR)C7, BSCB1(R)C10, RBS10(R)C2, JF10 × BS13(S1)C2, Caribbean flint‐dean, BSTL(S2)C4, IF10, and RSSSC had a significant number of dominant favorite alleles for grain yield not present in FRB73 × FRMo17. Because dominance was for unfavorable alleles for root and stalk lodging, frequencies of favorable recessives not present in one of the parents were used to measure the value of populations as sources to improve the hybrid. Of the eight populations with significant numbers of favorabe alleles for grain yield, only IF10 had a significant frequency of unfavorable dominant alleles for root lodging and all eight had a significant frequency of favorable recessives. None of the populations had a significant number of favorable alleles for stalk lodging resistance. The classification of relationships of populations to FRB73 or FRMo17 based on grain yield data agreed with pedigree information. Populations also were evaluated for their value as direct sources of new inbreds to use in combination with FRB73 or FRMo17. Of the populations tested, BS11(FR)C7 and BSCB1(R)C10 were most valuable either for improving parents of a hybrid or as direct sources of lines. Both populations had previously undergone recurrent selection for combining ability for grain yield in the central Corn Belt.