bluuebunny/crossref_metadata_2025 huggingface dataset:
A Growth Analysis Comparison of Corn Grown in Conventional and Equidistant Plant Spacing
Authors: Bullock D. G. , Nielsen R. L. , Nyquist W. E.
Published: July 2010

Corn (Zea mays L.) grown in an equidistant plant‐spacing pattern (EPS) often yields more grain per unit area of land than that grown in conventional plant‐spacing patterns (CPS). The objective of this study was to determine the effect of equidistant plant spacing on aboveground dry matter production in corn. Two hybrids (‘Pioneer brand 3732’ and ‘B73 ✕ LH58’) were grown in two planting patterns (EPS and CPS) in field studies on a Chalmers silty clay loam soil (Typic Haplaquoll) near West Lafayette, IN, in 1983 and 1984. Measurements of plant dry matter accumulation and leaf area development began at growth stage V4 and continued weekly through R6. Growth analysis components were estimated from growth curves fitted to the relationships between the measured plant variables (dry weight per plant and dry weight per leaf) and a temperature index measured in growing degree days (GDD). Crop growth rate was greater for EPS than for CPS early in the growing season for both hybrids. An increase in plant biomass was primarily responsible. Although relative growth rate (RGR) tended to be smaller for EPS compared to CPS, the data suggested that the increase in plant biomass caused by EPS may be related to an increased RGR prior to 400 to 500 GDD after planting. Net assimilation rate was not significantly increased by EPS early in the season. Early and mid‐season leaf area indexes, however, were greater for EPS for both hybrids.
Multiple‐Species Nematode Resistance in Soybean: Effect of Genotype and Fumigation on Yield and Nematode Numbers
Authors: Weaver D. B. , Rodriguez‐Kabana R. , Carden E. L.
Published: July 2010

Successful management of plant‐parasitic nematodes without the use of fumigant nematicides is a problem in the southeastern USA, especially when both root‐knot (RKN) (Meloidogyne spp.) and soybean cyst nematodes (SCN) (Heterodera glycines Ichinohe) occur in a mixed population in the same field. We studied the yield performance and nematode population numbers of several nematode‐resistant soybean (Glycine max L.) cultivars near Elberta, AL, for 3 yr in a Ruston fine sandy loam (sandy, siliceous, thermic, Psammentic Paleudults) heavily infested with a mixture of RKN [Meloidogyne incognita (Kofoid and White) Chitwood and M. arenaria (Neal) Chitwood] and SCN (a mixture of races 3, 4, and other unidentified races). Objectives were to evaluate performance of a group of soybean genotypes with differing combinations of resistance to RKN and SCN in terms of yield and effect on nematode populations in soil where both RKN and SCN occur together. Comparisons were made between plots that received no nematicide, and plots fumigated with a planting‐time application of 16.8 L ethylene dibromide ha−1. Four 2‐yr experiments were conducted in 1984 through 1986. Fumigation increased yield and decreased RKN numbers in all years and experiments and increased SCN numbers in all except one experiment in 1984. All cultivars sustained high RKN populations 6 wk before harvest; this was especially true for ‘Kirby’ and ‘Leflore’, two of the highest‐yielding cultivars in fumigated and nonfumigated plots. The RKN numbers and yield were not often correlated in nonfumigated plots. Cultivars significantly affected yield except for one experiment in 1985 and often significantly affected RKN numbers and always significantly affected SCN numbers. We concluded that even cultivars with multiple‐nematode resistance show differential yield response to these mixed populations, and that breeding for multiple‐nematode resistance is an effective means of reducing yield losses. If nematicide use is economical, it should be used with the most resistant cultivar available.
Combining Ability of Tannin Content and Protein Characteristics of Raw and Cooked Dry Beans
Authors: Wassimi N. N. , Hosfield G. L. , Uebersax M. A.
Published: July 2010

Tannin in dry bean (Phaseolus vulgaris L.) seeds has been associated with low protein availability and digestibility. Protein losses may occur during soaking and cooking and lessen the potential nutritional benefit from eating beans. The aim of the present study was to evaluate general combining ability (GCA) and specific combining ability (SCA) effects on tannin content and protein characteristics of dry and cooked beans. A fixed‐effect model permitted the evaluation of parents for use in breeding programs to improve bean nutritional quality. Eight parents were crossed in diallel to produce the F2 and F3 generations on which combining ability mean squares and genetic effects were calculated. Tannin was determined by the vanillin‐HCl method and protein of dry and cooked beans was measured using an infrared reflectance instrument. Protein loss during soaking and cooking was determined by subtracting the protein in cooked beans from that in dry beans. Significant differences were detected among parents and progeny for all traits, indicating the presence of genetic variability. Mean squares for both GCA and SCA were significant, indicating the presence of additive and dominance effects in the populations. Ratios of GCA:SCA mean square components were greater than unity for all traits, indicating that GCA predominated. Maternal effects influenced tannin content. The distribution of points representing the parental arrays along the regression line of the Wr, Vr graph revealed that genes with partial dominance controlled tannin content. Genes for protein content of raw and cooked beans showed partial dominance in some cases and complete dominance in other cases. Genes controlling the protein loss trait had the property of complete dominance. Seed protein contents of raw and cooked beans were correlated but raw bean protein and tannin were not. Study results suggested that it is not feasible to simultaneously breed for multiple traits, except for seed protein of raw and cooked beans. Screening for raw bean protein and tannin content should be done independently.
Soybean Cyst Nematode Effect on Soybean Grown at Controlled Soil Water Potentials
Authors: Young L. D. , Heatherly L. G.
Published: July 2010

Soybean [Glycine max (L.) Merr.] grown in fields infested with soybean cyst nematodes (SCN), Heterodera glycines Ichinohe, produces lower yields when soil moisture is deficient than when soil moisture is adequate. The relative contribution of moisture and nematode stress to decreased yields has not been determined. The objective of this study was to determine the effect of SCN on soybean grown at controlled soil water potentials (SWP) in the upper profile. Upper‐profile (0 to 0.30 m) SWP in a Vicksburg sandy loam soil (coarse‐silty, mixed, acid, thermic, Typic Udifluvents) was maintained at wet (−20 to −40 J kg−1) and dry (−60 to −80 J kg−1) levels in outdoorain‐sheltered microplots and in greenhouse pots that were either infested or noninfested with SCN. Wet plots yielded more seed than dry plots and noninfested plots had greater seed yield than infested plots. Soil water potential and SCN effects on seed yield appeared independent. Number of pods and leaflet area at R5 were reduced by both lower SWP and presence of SCN. Soil water potential effects on SCN numbers at harvest were inconsistent. Lower soybean yields in SCN‐infested fields during years of deficient rainfall are apparently due to both drought and nematode stress.
An Electronic Meter for Determining Ease of Tripping of Alfalfa Florets
Authors: Teuber L. R. , Knapp E. E. , Chaney D. E. , Paige D. F.
Published: July 2010

Numerous methods of assessing ease of tripping of alfalfa (Medicago saliva L.) florets have been reported. The objective of this research was to develop a device that would accurately measure ease of tripping. Four florets from each of 72 greenhouse‐grown alfalfa plants chosen randomly from ‘CUF‐101’ were tested with the electronic tripping meter on two dates. Concurrently, tripping measurements were also obtained on 68 of the same 72 plants using ethanol. Ease of tripping values measured by the ethanol and electronic tripping meter techniques were correlated (r = 0.32*, significant at the 0.05 probability level; 66 df), but ease of tripping values were more repeatable with the electronic tripping meter than with the ethanol method. Spearman's coefficient of rank correlation between sampling times was greater for values obtained using the electronic tripping meter (r = 0.61**, significant at the 0.01 probability level; 70 df) than for values obtained using ethanol (r = 0.18, 66 df). The electronic tripping meter was a more accurate, more repeatable, and a less time‐consuming method.
Resource Allocation in Experiments Measuring Soybean Tolerance to Soybean Cyst Nematode
Authors: Reese P. F. , Boerma H. R. , Hussey R. S.
Published: July 2010

Genotypic variability in soybean, Glycine max (L.) Merr., for tolerance to soybean cyst nematode (SCN), Heterodera glycines Ichinohe, has recently been reported. The measurement of soybean tolerance to SCN requires twice the land area and is more expensive compared with yield testing. The objectives of this research were to estimate the coefficients of variation (CV) and error variances (σ2) for different plot designs from two experiments measuring tolerance to SCN and to determine efficient resource allocation for future experiments. The CV for tolerance index [(yield in untreated plot ÷ yield in nematicide treated plot) ✕ 100] ranged from 0.15 to 0.48 for various hill‐plot designs (one to eight hills/plot) and ranged from 0.18 to 0.33 for various row‐plot designs (1.78 to 7.10 2 harvested). The error variances ranged from 108 to 1131 for the hill‐plot designs and ranged from 106 to 579 for the row‐plot designs. Unbordered hill and row plots had similar CV compared with bordered plots. Assuming no genotype ✕ environment interaction (σ2GE), six and two replications would be required to detect a 50% difference in the experimental mean between two geneotypes using one and eight hills/ plot without borders, respectively. Unbordered row plots of 1.8 m and 7.32 m length (row width = 0.97 m) would require four and two replications, respectively, to detect the same level of difference. The σ2GE expressed as a fraction of σ2 was below 0.10 for all plot designs except one. Assuming σ2GE = 0.1 σ2, a 30% difference in the experimental mean between two genotypes can be detected with three replications in each of two environments with the 7.32‐m row plot design. These results are discussed in regard to efficient allocation of resources for measuring tolerance to SCN.
Variability in a Collection of Alfalfa Germplasm from Morocco
Authors: Rumbaugh M. D. , Graves W. L. , Caddel J. L. , Mohammad R. M.
Published: July 2010

It is expensive to incorporate extensive collections of exotic plant germplasm into breeding programs directed toward the improvement of quantitatively inherited agronomic traits. A pooling of accessions based on similarity of geographic origin or on a high degree of phenotypic resemblance in early screening trials would reduce these expenses. Our objective was to determine whether or not such a procedure was possible with a recent alfalfa (Medicago sativa L.) germplasm collection from Morocco. A collection of 146 accessions of alfalfa from Morocco was evaluated for 28 traits measured in greenhouse and field experiments. Each accession was assigned to one of five landraces defined by the geographic regions in which the accessions were collected. Seventy‐eight percent of the assignments were valid as judged by discriminant analysis. Accessions from two of the regions were. distinctly different from each other and from those of the other three regions which were quite similar. Spotted alfalfa aphid [Therioaphis maculata (Buckton)] resistance and germination in 1.2 S m−1 NaCl solution were the two most important discriminating variables. Accessions with high levels of insect resistance were obtained only in the Atlanticoastal region and are believed to be recently introduced cultivars. Alfalfa breeders selecting for quantitatively inherited adaptive traits could pool the accessions to form five or fewer populations with little risk of significantly decreasing the variability.
Pathotoxin‐Induced Alteration in Protein Synthesis Associated with Susceptibility of Sorghum to Milo Disease
Authors: Traylor Elbert A. , Dunkle Larry D. , Schertz Keith F.
Published: July 2010

Symptoms of milo disease of sorghum, Sorghum bicolor (L.) Moench, caused by the fungus, Periconia circinata (Mangin) Sacc., can be elicited selectively in susceptible genotypes by treatment with the host‐specific toxin produced by the fungus. Sorghum lines with diverse genetic backgrounds were examined to determine whether disease susceptibility is correlated with an enhanced rate of synthesis of 16‐kilo dalton proteins induced by the toxin. Test materials included near‐isogenic susceptible and resistant lines of grain sorghum ‘Colby’, susceptible and resistant selections of shattercane, toxin‐sensitive selections from China and Nigeria, and spontaneous resistant mutants of Colby. Protein synthesized in root tips after treatment with the toxin were labeled in vivo with [3H]‐leucine, separated by polyacrylamide gel electrophoresis, and detected by fluorography. Toxin treatment enhanced the rate of synthesis of the 16 kD proteins in all susceptible selections but not in any of the resistant selections. These results establish a correlation between susceptibility of sorghum to P. circinata and an increased rate of synthesis of 16 kD proteins induced by the host‐specific toxin from P. circinata.
Chromosomal Locations of Genes for Traits Associated with Lodging in Winter Wheat
Authors: Al‐Qaudhy W. , Morris R. , Mumm R. F. , Hanna M. A.
Published: July 2010

Lodging in wheat (Triticum aestivum L.) is a complex character which is influenced by morphological traits as well as environmental conditions. Wheat breeding programs would benefit from cytogenetic information on lodging and associated traits. Reciprocal substitutions between the hard red winter wheats, ‘Wichita’ and ‘Cheyenne’, for all chromosomes except Cheyenne 2B in Wichita were used to investigate additive and interactive effects of individual chromosomes on nine traits previously reported to be associated with lodging. Duplicate lines for each chromosome except Cheyenne 3B in Wichita were included to check background homogeneity. Straw strengths were measured by using an Instron universal testing machine (Instron Ltd., Canton, Ma) to break basal internodes of main tillers from plants grown in a field on a Sharpsburg silty‐clay loam soil (fine, montmorillonitic, mesic Typic Argiudolls) at Lincoln, NE, with a randomized complete block design. Data on the other eight traits (height, length and diameter of basal internodes, number and width of inner vascular bundles, width of culm wall, diameter of culm cavity, and width of tissue from epidermis through sclerenchyma layer) were collected from main tillers of a greenhouse planting with an augmented randomized complete block design. Wichita and Cheyenne differed significantly only in plant height and basal‐internode length among the nine traits. Substitutions of Cheyenne chromosomes into Wichita produced almost three times as many significant phenotypic changes as substitutions of Wichita chromosomes into Cheyenne. Reciprocal effects were obtained for chromosomes 3B (number of vascular bundles and culm‐wail width) and 3D (basal‐internode diameter). Each of the three Cheyenne homoeologous Group 4 chromosome pairs increased the number of vascular bundles in Wichita. Cheyenne chromosomes 3B and 6A each produced favorable effects in Wichita on several traits related to lodging resistance. Other Cheyenne chromosomes with major effects on single traits in Wichita were 5D for straw strength, 7A for plant height, and 2A for number of vascular bundles. The use of reciprocal substitution lines revealed reciprocal effects of homologues as well as interactions between substituted chromosomes and specific genetic backgrounds.
Crossing and Morphological Relationships among Trifolium Species Closely Related to Strawberry and Persian Clover
Authors: Taylor N. L. , Gillett J. M.
Published: July 2010

The genus Trifolium consists of eight sections including Vesicaria, which might be termed the bladder clovers. Two centers of diversity within the section are the north Mediterranean region and the eastern part of Irano‐Taranian region. The two species of agricultural importance in the USA are the perennial strawberry clover (T. fragiferum L.) and the annual persian clover (T. resupinatum L.). The overall objectives of these investigations were to determine the evolutionary relationships among Vesicaria taxa, and to provide data for future possible interspecific hybridizations leading to improvement of the cultivated species of the USA as well as to authenticate the validity of nomenclature for taxa existing in the USDA world seed collection maintained at the University of Kentucky. To accomplish these objectives, breeding system, crossing and morphological relationships among eight taxa were examined in greenhouse investigations. Close similarities were indicated for two annual allogamous species, T. resupinatim and T. clusii. These species were considerably different from two other annual species, T. tomentosum L., and T. bullatum Boiss, both of which are autogamous. Among the perennial group, T. fragiferum appeared quite closely related to T. neglectum C.A.M. The other two perennial species, T. physodes Stev. ex M.B. and T. tumens Stev. ex M.B. are genetically isolated and morphologically different from each other and other species of the section. Shriveled seeds were produced from crosses of some species indicating the possiblity of producing interspecific hybrids via embryo rescue and tissue culture. Gene transfer among the species indicated as closely related by crossing investigations should be rather easy.
Tillage Effect on Seasonal Accumulation of Labeled Fertilizer Nitrogen in Sorghum
Authors: Locke M. A. , Hons F. M.
Published: July 2010

Limited information is available regarding tillage effects on seasonal N accumulation in sorghum [Sorghum bicolor (L.) Moench], especially where labeled N was used. Tillage effects on fertilizer N accumulation in 1985 and 1986 were evaluated in a field study on a Weswood silt loam (Fine‐silty, mixed, thermic Fluventic Ustochrept) near College Station, TX. Nitrogen‐15 depleted NH4NO3 (150 kg N ha−1) was surface broadcast or subsurface banded under no‐tillage or conventional tillage management to monitor fertilizer N accumulation in sorghum at boot, anthesis, soft dough, and harvest. Both years, most tillage effects on fertilizer N accumulation were manifested early in the season. The tillage‐by‐placement interaction was not significant for N uptake parameters, indicating a similar N accumulation response to placement for both tillage systems. Most fertilizer N uptake occurred by anthesis (84% averaged across years). Fertilizer N accumulation in no‐tillage sorghum was generally higher throughout the 1985 season, resulting in significantly greater fertilizer N recovery by harvest. This effect occurred even though yields and total N accumulations for both tillage systems were similar. No tillage difference in whole plant fertilizer N accumulation at harvest was observed in 1986. No‐tillage delayed early development of sorghum approximately 2 wk in 1986. Fertilizer N accumulation in leaves was less with conventional tillage than no‐tillage early in the 1986 season. Leaf fertilizer N did not differ between tillage treatments after anthesis when vegetative demand declined. Conventional tillage culms contained more fertilizer N thoughout the season. Tillage effects on panicle fertilizer N accumulation coincided with periods of high N requirement, such as at soft dough, when no‐tillage was higher. The plant growth delay for no‐tillage sorghum in 1986 may have subjected the crop to additional moisture or temperature stress resulting in a tillage by fertilizer placement interaction, whereby banded treatments produced more grain than broadcast in no‐tillage plots. Yields for banded no‐tillage sorghum did not differ from those for either placement treatment in conventional tillage plots.
Genetic Improvement in Agronomic Traits of Hard Red Winter Wheat Cultivars 1919 to 1987
Authors: Cox T. S. , Shroyer J. P. , Ben‐Hui Liu , Sears R. G. , Martin T. J.
Published: July 2010

Periodic evaluation of genetic improvement of crop cultivars is useful, both as a demonstration of the importance of plant breeding to the public and as a way of identifying traits or target environments that may require increased efforts by breeders. Evaluation of cultivars from different eras in a common environment is the most direct of the several methods that have been used to estimate breeding progress. Thirty‐five hard red winter wheat (Triticum aestivum L. em. Thell.) cultivars introduced or released between ca. 1874 and 1987 were evaluated in experiments at three locations in Kansas during 1986 and 1987 (three other cultivars were evaluated only in 1987) to estimate genetic progress achieved by hard red winter wheat breeding programs. Linear regression of cultivar means on years of release showed increases of 16.2 kg ha−1 yr−1 in grain yield, 0.4 kg m−3 yr−1 in volume weight, and 0.04 g yr−1 in thousand‐kernel weight. Days to heading and plant height decreased at rates of −0.1 d yr−1 and −0.5 cm yr−1, respectively. There were also significant increases over time in lodging resistance. There was no significant change in biomass yield over time. Rates of genetic improvement varied significantly across evaluation environments, with the greatest gain in grain yield (1.4% of the experiment mean per year) estimated in an epidemic of stem and leaf rust (caused by Puccinia graminis Pers. f. sp. tritici Eriks. & Henn., and P. recondita Rob. ex. Desm. f. sp. tritici, respectively). Moderate gain per year (0.6%) was estimated in the most highly productive environment, lower gain (0.4%) was found under drought stress, and there was no gain when evaluation was conducted under an epidemic of tan spot (caused by Helminthosporium tritici‐ repentis Died.), a foliar disease. High levels of resistance to H. tritici‐repentis had not been incorporated into hard red winter wheat cultivars. No evidence of a yield plateau was found for hard red winter wheat cultivars evaluated under a range of environmental conditions in Kansas.
Mitomycin C‐ and Streptomycin‐Induced Male Sterility in Cultivated Sunflower
Authors: Jan C. C. , Rutger J. N.
Published: July 2010

Worldwide hybrid sunflower (Helianthus annuus L.) production depends on a single source of cytoplasmic male sterility (CMS). Additional CMS sources would reduce the genetic vulnerability associated with the use of a single cytoplasm. The objectives of these studies were to evaluate the effectiveness of mitomycin C and streptomycin in inducing CMS in cultivated sunflower, and to evaluate fertility restoration relationships of induced CMS mutants with various restoration lines. Seeds of inbred maintainer line HA 89 were treated with mitomycin C and streptomycin. Induced male sterility was classified in M2 heads as sectorial, semisterile or complete and further verified by observing open‐pollinated M2 heads in progeny rows. Untreated HA 89 produced no CMS mutants. 5, 50, and 500 mg L‒1 mitomycin C treatments resulted in four total confirmed CMS mutants and the 5, 50, 500, and 5 000 mg L‒1 streptomycin treatments produced 18 total confirmed CMS mutants. Progeny of the 22 induced CMS mutants and CMS HA 89 crossed with fertility restorers RHA 266, RHA 274, RHA 280, and RHA 296 were all fertile. Seven nuclear gene controlled male‐sterile (NMS) mutants with monogenic recessive inheritance were also verified. Streptomycin was a more effective mutagen than mitomycin C for inducing CMS mutations in sunflower. The induced CMS mutants can be used readily for hybrid seed production without altering current fertility restoration systems, and could provide alternative male‐sterile cytoplasm for sunflower hybrid production.
Independent Inheritance of Genes for Dhurrin and Leucoanthocyanidin in a Sorghum Cross
Authors: Haskins F. A. , Gorz H. J.
Published: July 2010

Flag leaves of KS8 sorghum [Sorghum bicolor (L.) Moench] are low in dhurrin [p‐hydroxy‐(S)‐mandelonitrile‐β‐D‐glucoside] content and thus in hydrocyanic acid potential (HCN‐p), and they contain little (if any) leucoanthocyanidin (LAC). Comparable leaves ‘Colman’ sorghum are intermediate in HCN‐p and high in LAC. This study was conducted to investigate the inheritance of HCN‐p and LAC in crosses of KS8 ✕ Colman. Flag leaves from field‐grown plants of both parents; the F1, KS8 ✕ Colman; the backcross, KS8 ✕ (KS8 ✕ Colman); and the F2, (KS8 ✕ Colman) selfed, were assayed for both HCN‐p and LAC. Assays for HCN‐p indicated that the backcross values provided a good fit to 1 intermediate:1 low (X2 = 0.05, P = 0.82) and F2 results to 3 intermediate:1 low (X2 = 0.96, P = 0.33). For LAC, backcross results were 1 LAC+:1 LAC− (X2 = 0.20, P = 0.65) and F2 values were 3 LAC+:1 LAC− (exact fit). Classification for both traits yielded good fits to 1:1:1:1 for the backcross (X2 = 0.30, P = 0.96) and 9:3:3:1 for the F2 (X2 = 3.24, P = 0.36). These results indicated that the difference in HCN‐p between Colman and KS8 depended primarily on a single gene, the difference in LAC depended largely on a separate single gene, and the HCN‐p gene and the LAC gene were not linked.
Contribution of the Long Arm of Chromosome 10 to the Total Haterosis Observed in Five Maize Hybrids
Authors: Lamkey K. R. , Hallauer A. R. , Robertson D. S.
Published: July 2010

Knowledge of the contributions of different chromosome segments to the expression of quantitative traits is limited. Information on the relative importance of loci on different chromosome arms could be used to identify blocks of genes that might be useful for improving inbreds and their hybrid progeny. One suggested technique to evaluate the relative importance of different chromosome arms of maize (Zea mays L.) for trait expression has been the use of B‐A translocations. The objective of our study was to measure the contributions of the 1OL segments from the inbreds B55, CI187‐2, Oh43, M14, and N25 to the total heterotic effect observed in the hybrid of W22 and the respective inbreds. Field studies were conducted that included three strains of W22, their crosses to B55, CI187‐2,Oh43, N25, and M14; and their crosses to five W22 lines that carried a substitution from each of the five non‐W22 lines for the distal 67% of the long arm of chromosome 10 (1OL). Data were collected for 11 plant and ear traits. Significant differences (P ≤ 5 0.05) were detected among the three strains of W22 and their crosses. The differences, however, did not show a consistent pattern among strains for the 11 traits. Significant midparent heterosis was detected for most traits in the hybrids of the normal and 10L segment lines for grain yield and components of yield. The percentage of midparent heterosis accounted for by the 1OL segment ranged from 9.4 to 20.8% for yield. There were differences among traits for the effects of segment 1OL on trait expression, with the greatest effect for tasselbranch number and the least for kernel weight. These studies suggest that the use of B‐A translocations to analyze more chromosome segments may be informative and may make possible the combining of different segments for creating superior lines and hybrids.
Development of Short and Coarse‐Fibered American Pima Cotton for Use as Parents of Interspecific Hybrids
Authors: Percy R. G. , Turcotte E. L.
Published: July 2010

Short, coarse‐fibered Pima (Gossypium barbadense L.) cotton strains may be desirable as parents of interspecific F1 hybrid cottons. This study was conducted to determine if selective advance toward short, coarse‐fiber types could be accomplished within a subset of Pima strains while maintaining adequate fiber strength, uniformity, and lint percentage. The fiber selection criteria of extralong length and fineness used for American Pima cotton were reversed within the subset. Two diallel tests were conducted at Maricopa and Marana, AZ in 1985. Significant (0.01 level) genotype mean squares and general combining ability (GCA) estimates indicated useful variability for shorter, coarser fiber. Comparisons of GCA and specific combining ability (SCA) sums of squares (SS) with the total sums of squares indicated that greater additive genetic variability was available for fiber micronaire (x̄GCA SS/total SS = 0.70) than for fiber length (x̄ GCA SS/total SS = 0.34). A single best parent could not be identified based upon GCA effects due to the necessity of simultaneous selection for several traits. Population variances and ranges, estimated from individual plant data from F1 and F2 generations grown in 1985 and 1986, were consistent with genetic segregation in the F2 generation for fiber length and micronaire. Broadsense heritability estimates ranged from 0.20 to 0.52 for 2.5% span length and from 0.51 to 0.69 for micronaire in the F2 populations. Transgressive segregation was observed in F2 populations for shorter and coarser fiber. Selective advance toward Pima cotton with short, coarse fiber appears possible, but progress is expected to be slow.
Heritability of Seed‐Filling Period Estimates in Soybean
Authors: Pfeiffer T. W. , Egli D. B.
Published: July 2010

Soybean [Glycine max (L.) Merr.] yield has been positively associated with seed‐filling period, and soybean genotypes have been identified that exhibit significant differences in seed‐filling period. This experiment was conducted to obtain heritability estimates of the seed‐filling period duration based on effective filling period (EFP) and growth stage measurements, to determine the effect of stem termination type on the heritability estimates, and to measure the correlations between seed‐filling period length, and maturity and seed size. Data were collected on four populations in the F2, F2:3, and F2:4 generations from 1983 through 1986 at Lexington, KY on a Maury silt loam (fine, mixed, mesic Typic Paleodalfs) soil. Parent (F2:3)‐progeny (F2:4) regression gave nonsignificant heritability timates for EFP in all four populations (−0.11–0.22), highly significant estimates for duration of the R5 to R7 period in three of the four populations (0.16–0.63), and highly significant estimates all populations for duration of the R1 to R8 period (0.37–0.82). Seed size was rarely correlated with filling‐period duration. For the four populations, maturity was positively correlated with R1 to R8 in three, with R5 to R7 in two, and with EFP in none. Stem termination class did not affect heritability estimates. In populations segregating for stem termination, however, determinate genotypes were preferentially identified as having long R5 to R7 periods. The EFP was not a useful selection criterion in these segregating populations. For the duration of the R5 to R7 period to be a useable selection criterion, selection will need to be performed in separate subpopulations of the different stem termination types with attention being paid to the maturity of the genotypes selected.
Inheritance of Heat‐Induced Brown Discoloration in Seed Coats of Cowpea
Authors: Patel P. N. , Hall A. E.
Published: July 2010

Cowpea [Vigna unguiculata (L.) Walp.] accession TVu 4552 useful in breeding programs as a donor of heat tolerance during flowering. Unfortunately, seed coats of TVu 4552 and some other cowpea strains (e.g. ‘TVx 3236’) develop a pronounced brown discoloration when the plants are grown under hot air temperatures. The browning is intraceilular and confined to the seed coat. It does not influence germination, but it makes the grain less desirable to consumers. Inheritance of browning was studied in crosses of TVu 4552 with ‘California Blackeye #5’ (white seed coat, blackeye), ‘Bambey 21’ (white seed coat, no eye), and PI 204647 (kaiser brown seed coat, no eye) whose seed coat colors were not affected by high air temperatures. Segregation for seed coat browning was determined by observing the frequency of plants that produced at least some seeds with some brown discoloration, and plants for which all seeds had normal seed coat color. Analysis of F1, F2, F3, and backcross progenies showed that the seed coat browning reaction is dominant to normal seed coat color and governed by a single nuclear gene. It is suggested that this gene be designated as Hbs. No linkage was observed between Hbs‐controlled seed coat browning and the gene governing heat tolerance during floral bud development in TVu 4552. Similarly, no apparent association was observed between the development of normal brown seed coat pigmentation in PI 204647 and heat‐induced brown seed coat discoloration controlled by Hbs.
Diallel Analysis of Tolerance of Drying Injury in Seed Corn
Authors: Bdliya P. M. , Burris J. S.
Published: July 2010

Exposure to high temperatures during artificial drying of high moisture seed corn (Zea mays L.) may result in reduced seed quality and lead to poorer germination, reduced stand, and lower seedling vigor. The purpose of this research was to study the influence of the male parent on the female parent and to determine the genetic variation for tolerance of high drying temperature among hybrid seed from six inbred lines. Seed from diallel crosses, including reciprocals of the inbreds A632 (tolerant of drying injury), A641, B14A, B73, W64A (intermediate), and Mo17 (intolerant) were harvested at 500g kg−1 (high harvest moisture, HHM) and dried at 50 °C to ca. 120g kg−1 in 1984 and 1985. Hybrid seeds were evaluated in the laboratory for tolerance of drying injury in warm (standard) and cold germination tests. Greater variation in germination percentage was observed among lines when used as female parents than when the lines were used as male parents. The influence of an inbred as pollen parent was not significant. Maternal effect mean squares were 1.5 and 3.3 times greater than those of general combining ability (GCA) and specific combining ability (SCA), respectively, for warm germination tests. GCA mean squares were however 1.5 and 8 times greater than those of maternal and SCA respectively, for cold germination testing. Additive and maternal effects were more important than nonadditive and reciprocal effects in the variation for tolerance of drying injury among these six lines. This suggests that most of the variability observed among seeds for tolerance of drying injury was associated with maternal and or cytoplasmic inheritance. Environment (year), however, had a significant effect on the contribution of these genetic components.
Water Status Effects on Net Photosynthesis in Field‐Grown Alfalfa
Authors: Nicolodi Chiara , Massacci Angelo , Di Marco Giorgio
Published: July 2010

Net photosynthesis (Pn) typically declines with drought. Partitioning of this decline into stomatal and nonstomatal factors determines the seasonal performance and stress adaptation of the leaves. Here stomatal and nonstomatal limitations to Pn in alfalfa (Mediago sutiva L.) are evaluated to determine their relative importance during drought. Photosynthesis of the upper leaves of irrigated and nonirrigated alfalfa (cv. Sabina) was determined in 1985 and 1986 during spring regrowth. In both years, Pn was inhibited more than 35% in nonimgated compared with irrigated plants, which had higher leaf water potential. Internal CO2 partial pressure (pi) indicated that stomatal limitation was not the only reason for reduced Pn, stomatal and nonstomatal effects were about equally important in the inhibition of Pn in leaves of nonirrigated plants in 1986. In vitro ribulose‐ 1,s‐bisphosphate carboxylase activity (RuBPCO) per unit leaf area was higher in the nonirrigated treatment, suggesting that the enzyme was not responsible for the nonstomatal component of inhibition of Pn. In 1986, O2 evolution, measured in detached leaves with saturating CO2, was lower in the nonirrigated treatment compared to the irrigated one, implying that limitations to ribulose‐1,Sbisphosphate (RuBP) regeneration may play a significant role. The carbon isotope composition of total leaves of plants collected at the end of the experiment in 1985 and 1986 showed a lower discrimination against 13C in nonirrigated compared with the irrigated leaves, indicating a reduced conductance to C02 transfer. It is concluded that both stomatal and nonstomatal mechanisms contributed to reduced Pn in droughted alfalfa.
Tetrazolium Test for Predicting the Seedling Vigor of Rice at Optimal and Low Temperatures
Authors: Sung F. J. M. , Chen J. J.
Published: July 2010

The amount of formazan extracted from tetrazolium salt‐treated embryos has been used to predict seedling vigor in some cereal crops. Our objective was to determine whether this technique could be used to evaluate the seedling vigor of rice (Oryza sativa L.) cultivars grow at different temperatures. In this study, the genetic differences in formazan production capability of the embryo and its relationship to seedling vigor, as indicated by seedling dry weight accumulation within a 7‐d growing period, were examined in 21 cultivars. The results indicated that temperature treatments could play a crucial role in regulating the seedling growth response and formazan production capability in the embryo portion of the seed. Considerable variation in growth and formazan production level also existed in the rice cultivars. Seedling vigor was positively related to formazan production capability of the embryo, suggesting that the formazan extraction technique would be a simple and reliable method for screening rice cultivars for optimal and suboptimal temperature seedling vigor.
Effects of Insect Pollination and Season on Seedling Emergence in Guayule
Authors: Mamood A. N. , Ray D. T. , Waller G. D.
Published: July 2010

Stand establishment in guayule (Purthenium argentatum A. Gray) by direct seeding has not been successful due mainly to low seedling emergence. This field study was conducted in 1984 and 1985 in Tucson, AZ to evaluate the effect of honey bee (Apis melfiferu L.) pollination and different times of seed production within a season on guayule seedling emergence. The experiments involved four cultivars with four pollination treatments: plants caged with bees; plants caged without bees; plants open‐pollinated (uncovered); and plants individually covered with bags. Seeds were collected monthly from July through September in 1984, and from May through September in 1985. All cultivars responded positively to honey bee pollination with increased seedling emergence. The mean percentage of seedling emergence of seed produced in plots visited by bees (56%) was significantly greater than in those from plots without bees (15%). Seeds collected in May and September had the highest emergence percentages. These results demonstrated that (i) insect pollination can increase emergence of resulting seed in guayule, and (ii) seeds produced during the warmest months have lower emergence percentages.
Improvement of Resistance to Ear and Stalk Rots and Agronomic Traits in Tropical Maize Gene Pools
Authors: De León Carlos , Pandey Shivaji
Published: July 2010

Ear and stalk rots of maize (Zea mays L.) caused by Fusarium moniliforme (Sheldon) limit maize production in the lowland tropics. A modified ear‐to‐row (MER) selection scheme was used, with minor changes, to improve resistance to these diseases and five agronomic traits in eight tropical maize gene pools. Six pools were selected for stalk‐rot resistance (SRR) and two for ear‐rot resistance (ERR). Each pool included approximately 500 half‐sib (HS) families, and the selection intensity among and within families was adjusted so as to maintain this population size during each cycle of selection. Family selection was based on single‐row plots of 16 to 21 plants in one or two environments. Data on grain yield, plant and ear height, days to 50% silking (DS), lodging, disease and insect reaction, and plant and ear uniformity were recorded at appropriate stages of plant development. One cycle of selection was completed season−1. Selection for disease resistance was practiced under artificial inoculation. Averaged over pools, progress from selection (linear response) was 2.50** (significant at the 0.01 probability level), −0.15**, −0.35**, −1.66**, and −0.90% cycle−1** for yield, DS, plant height, SRR, and ERR, respectively. Yield improvement (linear response) averaged higher in pools selected for SRR (3.02% cycle−1**) than in those selected for ERR (1.38% cycle−1**). In the reduction of DS and plant height, however, greater progress was made in pools selected for ERR (−0.50** and −0.75% cycle−1**, respectively) than in those selected for SRR (−0.04** and −0.25% cycle−1**, respectively). Results indicate that the MER selection scheme employed by the International Maize and Wheat Improvement Center (CIMMYT) was effective in increasing grain yield, SRR, and ERR; and in reducing DS and plant height in maize.
The Loci Fr1 and Ep Define Soybean Linkage Group 12
Authors: Griffin J. D. , Broich S. L. , Delannay X. , Palmer R. G.
Published: July 2010

A study was conducted to verify linkage between the loci Fr1 (root fluorescence) and Ep (seed coat peroxidase activity level) in the soybean, Glycine max (L.) Merr., as well as to test for linkage between the two loci and various other markers. Crosses were made between a standard cultivar (Minsoy) and a diverse selection of lines; the crosses included reciprocals and both linkage phases. The F1 plants were grown in five different location/year combinations. Segregation data for F2 confirm that Fr1 and Ep are linked. The combined estimate of linkage, based on 6734 F2 individuals, indicates that Fr1 and Ep are separated by a distance of 41.4 ± 0.8 cM. Genes Fr1 and Ep were tested for linkage with several cytological and genetic markers in segregating F2 populations. Linkage Group 12 is not physically linked to the trisomic chromosomes A, B, C, or D or to those chromosomes involved in a chromosome interchange from G. soja (Sieb. et Zucc.) PI 101404B. Linkage Group 12 also is independent of the loci Aco4, Dia1, Idh1, Pb, Sod1, Sp1, T, W1, Y9, and probably Ap.
Comparison of Logistic and Weibull Functions: The Effect of Temperature on Cumulative Germination of Alfalfa
Authors: Bahler C. , Hill R. R. , Byers R. A.
Published: July 2010

The logistic and Weibull functions are mathematical equations that have been used to describe the characteristic curve of cumulative germination of plant seeds. The three objectives of this study were to determine (i) if either the logistic or Weibull function described the efffect of temperature on cumulative germination of alfalfa (Medicago sativa L.) seed; (ii) if the parameters of the equations could distinguish differences in germination among seed sources; (iii) and if either equation was predictive. ‘Saranac AR’ alfalfa seed was germinated at 5, 15, 25, or 35 °C over a period of 14 d in petri dishes containing filter paper saturated with distilled water. The logistic and Weibull functions both fit the curves generated by the four temperatures. Validation was accomplished by repeating the germination procedure described above at 10 and 20 °C with a germination period of 10 d and seed lots of six alfalfa cultivars. Parameters were estimated for the validation data set and prediction of the validation data set occurred using parameters estimated from the original data set. Both the Weibull and logistic functions gave satisfactory fits to the validation data set, but more accurate predictions of the validation data set were obtained with the Weibull than with the logistic equation derived from the original data set. The shape and scale Weibull parameters indicated that temperature and cultivar affected the rate of germination or vigor of the cultivars. However, the rate parameter of the logistic equation did not indicate any difference between the varieties. Therefore, use of the Weibull parameters increased the amount of information available for selecting for vigorous germination.
Chickpea Evaluation for Cold Tolerance under Field Conditions
Authors: Singh K. B. , Malhotra R. S. , Saxena M. C.
Published: July 2010

Chickpea (Cicer arietinum L.) yields are higher when plantings are made in early winter in the Mediterranean region instead of during the traditional spring season, but winter killing is often a problem. Cold tolerant chickpea cultivars are needed to successfully utilize a winter sowing approach. A study was conducted at the International Center for Agricultural Research in the Dry Areas (ICARDA), Tel Hadya, Syria during 1982 to 1983 with the objective of developing a field screening technique for cold tolerance in chickpea, and to identify sources of tolerance. A set of previously identified tolerant, intermediate, and susceptible lines was sown from mid‐fall to early spring. All susceptible lines sown during October were killed from cold injury, showing that the crop was more susceptible at the late vegetative stage than at the seedling stage. Consequently, a field screening technique was proposed, with an October sowing date to allow the crop to grow to the late vegetative stage before the onset of severe winter. Susceptible checks are grown at frequent intervals and evaluation takes place after the death of the susceptible check. This is followed by confirmation of tolerance. A 1 to 9 visual score was used to evaluate germplasm for cold tolerance. A total of 3276 germplasm accessions and breeding lines were evaluated from 1981 to 1987. Twenty‐one lines were identified as tolerant. Cold tolerance was not associated with the phenotypic traits of leaflet area, seed size, time to maturity, plant height, or growth habit.
Additional Locus with a Recessive Allele for Red Testa Color in Peanut
Authors: Holbrook Corley C. , Branch William D.
Published: July 2010

Seed with red testa color in peanut (Arachis hypogaea L.) are sold as oil stock at reduced price when mixed with tan or pink seed. Although two loci (R1 with a dominant allele for red testa and r2 with a recessive allele for red testa) have been identified, they do not explain all observations for inheritance of red testa. This study was conducted to better define the inheritance of red testa color in peanut and present evidence for a third locus controlling red testa inheritance. Three cross combinations involving five parents having pink or tan testa color were examined. The cross combinations were GA‐T2465 ✕ Tifton‐8, Tifton‐8 ✕ ‘Early Brunch’, and ‘Southern Runner’ ✕ ‘Sunbelt Runner.’ The F2 populations were field grown and examined for testa color. Data for each population fit a 15 tan or pink to 1 red testa segregation ratio. Examination of F3 lines also indicated that segregation for red testa color in these crosses was controlled by complementary recessive alleles at two loci. Because only one locus with a recessive red testa color allele has previously been identified, these results indicated the existence of at least one additional locus with a recessive allele for red testa color. It is proposed that the genotypes for the nonred parents GA‐T2465 and Tifton‐8 be designated r2r2R3R3, and R2R2r3r3, respectively.