bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Aspartate‐derived Amino Acids and Aminoethyl Cysteine on Growth of Excised Mature Embryos of Maize1
Authors: Green C. E. , Donovan C. M.
Published: July 2010

Twenty‐one amino acids were tested individually for their effects on growth of roots from excised mature embryos of maize (Zea mays L.). Among these, tryptophan, tyrosine, threonine, and homoserine were partially inhibitory to root growth at 1 mM concentrations. Length and dry weight data showed that maize roots both from embryos and from kernels were synergistically inhibited by lysine + threonine but not other paired combinations of aspartate‐derived amino acids. Roots from embryos, however, were more sensitive to inhibition. The synergistic inhibition of embryo root length was near maximal at 1 mM lysine + 1 mM threonine. This synergism was not observed with other paired combinations of aspartatederived amino acids. Methionme and homoserine specifically relieved lysine + threonine inhibition, whereas 17 other amino acids were ineffective. These results are compatible with a model and published enzymology studies which suggest that exogenously added lysine and threonine may act as feedback inhibitors of aspartokinase and homoserine dehydrogenase, respectively, early enzymes in the aspartate biosynthetic pathway.

The lysine analog, S‐2‐aminoethyl‐L‐cysteine (AEC) was a potent inhibitor of root growth in maize seedlings. Among 21 amino acids tested, lysine was most effective in relieving AEC inhibition while arginine and methionine were partially effective.
Variability in Root System Characteristics of Kleingrass Seedlings1
Authors: Rischler C. R. , Monk R. L.
Published: July 2010

Stand establishment of kleingrass (Panicum coloratum L.) is often reduced because of an inadequate root system. Growth characteristics of the primary root and the variability in numbers of adventitious roots on the sub‐coleoptile internode were examined during preemergence and postemergence. The “terminal preemergence length” of the primary root was 1.0 cm and ranged from 0 to 3.0 cm until the coleptile reached the soil surface, at which time primary root growth resumed. The resumption of growth was not a response to photosynthate, however, as 5 min of light per day was as promotive as continuous light.

The number and length of basal adventitious roots were independent of the primary root length. The cultivar ‘Kleingrass 75’ appears to be variable for both primary root growth characteristics and for adventitious root growth. Differences in both traits could be used in a breeding program to improve seedling establishment.
Host Preferences and Reproduction of Four Cereal Aphids on 20 Avena Selections1
Authors: Kieckhefer R. W. , Jedlinski H. , Brown C. M.
Published: July 2010

Host preference and reproduction of Schizaphis graminum (Rondani), Macrosiphum avenae (F.), Rhopalosiphum padi (L.), and R. maidis (Fitch) were tested seedling and mature (dough‐stage) plants of nine cultivars and nine experimental lines (Illinois) of Avena sativa L., one of A. strigosa Schreb., and one of A. fatua (L). graminum reproduced less (P < 0.05) on two Illinois lines (IL 70‐1556, IL 70‐1490) previously identified as bring tolerant to barley, yellow dwarf disease. M. avenae, R. padi, and S. graminum reproduced on both growth stages of the range of Avena selections; there were no differences (P > 0.05) in the responses of M. avenae and R. padi to the Avena selections. R. maidis did not reproduce on mature Avena.
Cytological and Electrophoretic Investigations of the Origin of ‘Callie’ Bermudagrass1
Authors: Burson Byron L. , Tischler Charles R.
Published: July 2010

‘Callie’ bermudagrass (Cynodon dactylon var. aridus Harlan et de Wet) is a vigorous, robust form selected as an aberrant plant from a plot of PI 290814 bermudagrass (C. dactylon L. Pets.). Since Callie differed markedly from the original introduction, a cytological and electrophoretic investigation was undertaken in an attempt to determine how it originated. Callie and PI 290814 had a chromosome number of 2n=4x=36. Meiosis was regular in both plants and their chromosome pairing behavior was similar with primarily bivalent pairing. Pollen stainability in Callie was 46%. Seed set ranged from 1.0 to 3.2% in Callie and was 1.0% in PI 290814. Embryo sac development was normal and there was no evidence of ovule abortion in either plant. Thirtythree selfed progeny from Callie showed a considerable range in morphology and vigor, illustrating a high degree of heterozygosity. None were as large or vigorous as Callie, indicating an inbreeding depression after one generation of selling. Electrophoresis demonstrated qualitative differences in the water‐soluble proteins in leaf tissue of Callie and PI 290814. This eliminates mutation as a means of Caliie's origin. These findings suggest that Callie probably originated as a natural hybrid between PI 290814 and a giant, tetraploid form of C. dactylon var. aridus. Its size and vigor are probably the result of heterosis as well as characteristics from the pollen parent.
Yield Responses to Selection for Variable R‐nj Expression in Early Maize1
Authors: Cross H. Z.
Published: July 2010

A mass selection technique for variable expression of R‐nj aleurone pigmentation in an unreleased, experimental, early maize (Zea mays L.) synthetic (NDSC) was initiated to determine if selection for the degree of anthocyanin pigmentation of the R‐nj allele would produce corresponding changes in yield or yield components. Selection for high and low R‐nj color expression was accomplished by pollinating a group of NDSC plants with a mixture of pollen from agronomically selected NDSC male plants and pollen from plants homozygous for the dominant R‐nj allele and subsequently rating the few heterozygous kernels for proportion of the kernel exhibiting anthocyanin. Ears from the first cycle of selection were intercrossed and yield tested at two locations. Results indicated that selection for high anthocyanin expression produced improved yields at both locations. Selection for low color expression also increased yields in one test environment. Yield increases were not accompanied by changes in ear moisture content at harvest.
Water Stress Effects on CO2 Assimilation, Photosynthate Partitioning, Stomatal Resistance, and Nodule Activity in Soybean1
Authors: Finn Gary A. , Brun William A.
Published: July 2010

14CO2 assimilation, photosynthate distribution, stomatal resistance, and acetylene reduction activity of vegetative soybean plants [Glycine max (L.) Merr., var. ‘Clay’] were examined 3 hours after pulse labeling the leaves with 14CO2. The plants had previously been water stressed for 20 hours by polyethylene glycol additions to the culture solution. Photosynthetic CO2 exchange rate (CER) and acytelene reduction activity of control and water stressed soybean plants were also monitored for 6 hours following polyethylene glycol induced water stress.

14CO2 assimilation and specific nodule activity (SNA) decreased and stomatal resistance (r8) increased with increasing water stress in the 14CO2 labeling experiment. There was a significant negative correlation (r=−0.71) between SNA and r8• Dry weights of leaves, of stems plus petioles, and of nodules were significantly decreased in the water stress treatments, while root dry weights increased. Water stress resulted in a redistribution of 14C with a greater proportion of the 14C being translocated to the roots and nodules at the expense of the leaves.

In the time course study, CER decreased after the imposition of an abrupt water stress (−12 bar), but total nodule activity was not affected. It is suggested that in. hibition of nodule activity under long term water stress was not caused solely by the decreased CER, but also by changes in photosynthate pool sizes.
Effect of Reducing Plant Population on Yield and Kernel Characteristics of Sugary‐2 and Normal Maize1
Authors: Baenziger P. S. , Glover D. V.
Published: July 2010

The maize (Zea mays L.) endosperm mutant sugary‐2 (su2) has been proposed to modify the soft endosperm of opaque‐2 (o2) maize to a harder, more vitreous texture, but su2 o2 has smaller, lighter kernels and often yields less than o2. Sugary‐2 also yields less than normal maize. Little information is available concerning how su2 responds to different plant population densities or to competition during its vegetative or reproductive growth. This research studied the effect of reducing plant population by thinning at different times on yield, ear, and kernel characteristics of su2 and normal maize in the single cross maize hybrid Oh43 su2 × B37 su2 and its normal counterpart. The genotypes were planted at 74,775 plants/ ha and thinned to medium (49,850 plants/ha) and low (24,925 plants/ha) populations at seedling emergence, 30 days after emergence (DAE), 50 DAE, ad l0 days after midsilk (DAMS) and 20 DAMS.

Sugary‐2 had significantly less grain weight per ear, plot yield, kernels per ear, kernel volume and kernel weight, and significantly higher kernel density than the normal counterpart. The genotypes × plant population treatment interaction was nonsignificant indicating both genotypes responded similarly to the reduced plant population treatments. The higher populations had lower grain weight per ear, greater plot yields, and fewer kernels per ear than did the low populations. Reducing population density after pollination had a greater affect on yield and ear characteristics than reducing population density before pollination. Kernel density was unaffected by the reduced plant population treatments. The low 20 DAMS treatment had the largest kernel weight and volume. For this treatment su2 had smaller kernels weights and volumes than did normal. The lower plot yields of su2 were caused by fewer kernels per ear and lower kernel weight than normal.
Inheritance of Resistance to Septoria nodorum in Wheat1
Authors: Nelson L. R.
Published: July 2010

Six wheat (Triticum aestivum Lem. Thell) parents and all possible F1 crosses (reciprocals included) making up a diallel series were grown under greenhouse conditions and tested for glume blotch [caused by Septoria nodorum (Berk.) Berk.] reaction during the heading stage. Significant (P≥0.01) effects were found for general combining ability (GCA) and specific (SCA) combining ability. The wheat cultivars ‘Oasis’ and ‘Blueboy II’ had the largest GCA effects for resistance while ‘McNair 1813’ and ‘IAS‐20’ had GCA effects for susceptibility. The cross ‘Holley’ × Ga H69‐56A‐1 had the largest SCA effect for resistance while the crosses Holley × Blueboy II and Oasis × Blueboy II had the lowest mean disease rating in the study.
Field Emergence Comparisons of Opaque‐2 and Surgary‐2 Opaque‐2 Segregates in Two Maize Synthetics1
Authors: Loesch P. J. , Bailey T. B.
Published: July 2010

The improved protein quality associated with opaque‐2 (o2) maize (Zea mays L.) has not been widely used because grain yield, grain quality, and field stands generally are reduced relative to normal maize. This study was conducted to determine if the superior grain quality of sugary‐2 opaque‐2 (su2 02) would be expressed also in seedling emergence percentage, rate of emergence, and seedling weight by comparing 02 and su2 o2 segregates of S1 and S2 ears from two maize synthetics.

Very similar emergence responses were obtained [or the two endosperm classes when S1 segregates were examined. The means for emergence percentage, rate of emergence, and seedling weight favored the o2 phenotype over the su2 o2 phenotype; however, significant differences were obtained only [or rate of emergence and seedling weight.

Under the cold field conditions encountered when S2 segregates were examined, o2 kernels were significantly superior to su2 o2 in emergence percentage and rate of emergence. Opaque‐2 kernels were larger, heavier, and had lower specific gravity than su2 o2 kernels. Relationships among traits within endosperm classes were different than [or the pooled endosperm classes, however. Percentages of seedling emergence within the o2 and su2 o2 classes were positively correlated with specific gravity of S2 kernels and rate of emergence, but were negatively correlated with weight and size of kernels. The apparent contradiction reflects the negative relationship between seed size and specific gravity within both the 02 and su2 o2 classes. Heritability estimates for the emergence traits were large and suggest that selection for improved emergence should be effective within either of the endosperm classes. Seedling emergence of o2 was not improved by the superior kernel texture of su2 o2 contributed by the su2 gene.
Hybrids and Induced Amphiploids Involving Agropyron curvifolium, A. repens, and A. desertorum1
Authors: Dewey Douglas R.
Published: July 2010

Agropyron curvifolium Lange (2n=28) was hybridized with Agropyron repens (L.) Beauv. (2n=42). An amphiploid (2n=70) was produced by treatment of an F1 (2n=35) with colchicine. The purposes of this study were to determine the mode of pollination and nature of polyploidy in A. curvifolium; to describe the morphology, cytology, and fertility of F1 hybrids and a C0 amphiploid of A. repens × A. curvifolium; and to describe a threespecies amphiploid hybrid involving A. repens, A. curvifolium, and A. desertorum (Fisch. ex Link) Schult.

Most A. curvifolium plants were highly self‐sterile. Occasional quadrivalents in all A. curvifolium plants at metaphase I indicated that they were partial autoploids whose genome formula could be written as E1E1E2E2. Chromosome pairing in the F1 hybrids averaged 14.82I, 9.73II, 0.20III, and 0.03IV. Most, if not all, pairing was the consequence of autosyndesis. The genome formula of the F3 was designated as E1E2S1S2X.

Chromosome doubling of the F1 hybrid increased plant height 20 to 25 cm. The amphiploid was meiotically irregular, averaging 6.02 univalents at metaphase I, 1.43 laggards at anaphase I, and 2.01 micronuclei per quartet. In spite of meiotic Irregularity, the amphiploid produced 90% stainable pollen. Some C1 progeny were the result of crossing of the A. repens‐A. curvifolium C0 amphiploid (2n=70) to an A. repens‐A. desertorum C0 amphiploid (2n=70). The three‐species amphiploid hybrids averaged 71% stainable pollen. The three‐species amphiploid hybrids were the most vigorous plants in the study and they may warrant the attention of grass breeders.
Flowering Characteristics of Cicer Milkvetch Clones and Their Polycross Progenies1
Authors: Townsend C. E.
Published: July 2010

The flowering requirements of cicer milkvetch (Astragalus cicer L.) are not known. Many plants do not flower in a greenhouse environment or during the seedling year in the field. The primary objective of this study was to determine the relationship between the flowering characteristles of 34 parental clones in the greenhouse and field and the performance of their polycress progenies for similar characters in the field. All clones flowered during the first growth period in the greenhouse when brought from the field in late December. However, flowering did not occur on the regrowth of some clones in the greenhouse. Date of flowermg in the field during the year of establishment was more highly correlated to date of flowering on the regrowth(r = 0.68) than on the first growth (r = −0.12) of these clones in the greenhouse. After going through the winter in the field, all clones flowered profusely the following spring.

In the field during the seedling year the percent of nonflowering plants within polycross progenies ranged from 2 to 51. After going through the winter in the field, all plants in 13 of 34 progenies flowered the following spring; only 3.5% of the total population did not flower. On the regrowth in the second year the percent of nonflowering, plants within progenies ranged, from 4 to 40, which was similar to that in the seedling year. Percentage of nonflowering plants was significantly correlated with date of flowering during all three growth periods. In the field, date of flowering for the parental clones during the year of establishment was significantly correlated with date of flowering of their polycross progenies in the seedling year (r=0.61). Both the greenhouse and field data indicated that some genotypes did not require exposure to low temperature for flower induction whereas other genotypes did. The low temperature requirements for such genotypes remain to be determined.
Response of Soybean Populations to Inbreeding Under Two Photoperiods1
Authors: Sediyama Tuneo , Wilcox J. R.
Published: July 2010

Three soybean [Glycine max (L.) Merr.] populations were advanced four generations by single seed descent (SSD) under a 12 and 14‐hour photoperiod. The objective was to determine if the populations differed for seed yield plant maturity, height, and lodging, when advanced under these two photolperiods.

Advancing the three populatmns by single seed descent did not result in significantly different population means or variances for seed yields, maturity, plant height, or lodging under these photoperiods. However, early maturing determinate segregates in one cross did not survive under the 14‐hour photoperiod. Distribution of lines did vary in some crosses, with skewness toward early maturing and low yielding lines in two crosses and toward high lodging scores in one cross. However, these deviations from normal distributions were not consistently associated with photoperiod. The data indicated that advancing these populations four generations by SSD under these two photoperiods did not result in consistent changes in the populations for these agronomically important characteristics.
Selection for Resistance to Xanthomonas phaseoli in Dry Beans1
Authors: Webster D. M. , Temple S. R. , Schwartz H. F.
Published: July 2010

Seedling and adult resistance in dry beans (Phaseolus vulgaris L.) to Xanthomonas phaseoli (E. Smith) Dows. was evaluated on field and greenhouse plants of F4 families derived from two susceptible × resistant crosses. Over 90% of the variation among disease scores of field‐grown families was attributable to the regression on scores of greenhouse‐grown seedlings. Two greenhouse inoculation methods, leaf‐clipping and water‐soaking, accurately predicted field resistance of families. The greenhouse comparison of seedlings and flowering plants revealed that the differences among families were much greater than the interaction of families with developmental stage.

Heritability of disease severity in greenhouse tests, estimated by parent‐offspring regression (F2/F3) was comparable for both inoculation methods. Correlation estimates of 0.27 for leaf‐clipping and 0.28 for water‐soaking were obtained when P.I. 207262 was the resistant parent. A gression estimate of 0.62 was obtained for the heritability of disease severity after leaf‐clipping inoculation when ‘Jules’ was the resistant parent, indicating plant selection from crosses with Jules would be effective for identification of resistant lines.
Genetic Variability and Association of Maturity, Yield, and Quality Characteristics of Female Hops1
Authors: Roberts D. D. , Kronstad W. E. , Haunold A.
Published: July 2010

Twenty‐nine female hop, Humulus lupulus L., cultlvars were evaluated for genetic variability and associations among traits affecting maturity, yield, and quality. The following traits were measured: vigor, yield, lateral branch length, node and cone number per lateral, cones per vine, cone weight, flowering and harvest date, alpha and beta‐acid content, alpha:beta ratio, and lupulin content of the cones.

Highly significant differences among cultivars were found for all characters measured. The genetic coefficients of variation, broad sense heritability, and expected gains from selection indicated considerable genetic potential for improvement.

All agronomic characteristics except cone weight were positively correlated with yield. All phenotypic correlations of harvest date, lateral length, nodes per lateral, cones per vine, and cone yield were significantly positive.

Except for vigor, phenotypic correlations between agronomic characters, and alpha and beta‐acid content were either significantly positive or not diflerent from zero. Selection could be practiced on either group of characters without adversely affecting the other.

Path coefficient analysis of phenotypic correlation coefficients showed that lateral branch length and cones per vine have a more direct as well as an indirect effect on yield than vigor, flowering date, harvest date, nodes, per lateral, or cone weight. Early maturing, and high yielding hop cultivars are best obtained by selecting for increased lateral length and/or number of cones per vine.
Regrowth of Genotypes of Tall Fescue Differing in Yield per Tiller1
Authors: Zarrough Khames M. , Nelson C. J.
Published: July 2010

Tall rescue (Festuca arundinaeea Schreb.) genotypes that have a high yield per tiller also have a low number of tillers/plant arid low residual leaf area after cutting. Our objective was to evaluate the role of stored energy relative to residual leaf area during regrowth of genotypes that differed in yield per tiller. Regrowth following cutting was followed for 6 weeks using genotypes selected for low (LYT), medium (MYT), and high (HYT) per tiller. The pot experiment was conducted outside during late summer and fail 1977, and was repeated in the greenhouse during early spring 1978. Data for the two experiments were similar and so were combined.

When herbage was removed to leave a 5‐cm stubble to begin the experiment, number of tillers per pot was double and residual leaf area was nearly six times larger for the LYT genotype than for the HYT genotype. Concentration of water.soluble carbohydrates (WSC) in the stem bases was about 16% of dry weight for the HYT genotype and 10% for the LYT genotype. During the first 2 weeks of regrowth the HYT genotype utilized 235% more WSC per tiller than did the LYT genotype to support a rapid leaf growth rate, which in turn contributed to a greater CO2 exchange rate per pot. Mean crop growth rate (), mean net assimilation rate (), and mean relative growth rate () for the 6‐week regrowth period were also greater for the HYT genotype than for the LYT genotype. Relative leaf area growth rate (RLaGR) was initially high for the HYT genotype, then decreased by week 6 to a rate lower than that for the LYT genotype. Ratio of RGR/RLaGR exceeded 1.0 between week 4 and week 5 for the HYT genotype while the other genotypes did not reach the ratio of 1.0 by week 6. In contrast with the LYT and MYT genotypes, the HYT genotype had recovered its original concentration of WSC by week 6.
Use of Glandless Breeding Stocks to Evaluate Unknown Heliothis Growth Inhibitors (X‐Factors) in Cotton1
Authors: Shaver T. N. , Dilday R. H. , Wilson F. D.
Published: July 2010

A significant linear relationship (r = 0.86 to 0.90) was found between reduction in larval weight of tobacco budworm, Heliothis virescens (F•), and flowerbud gossypol content of 1) F3 progenies of Upland stocks crossed with three Texas race stocks (Texas 216, Texas 490, and Texas 1134) of cotton, Gossypium hirsutum L., and 2) 221 entries from the race stock collection. Most of the suppression of growth of larvae which fed on diets containing extracts of progenies from the three race stocks could be attributed to gossypol or to other compounds that occur in pigment glands and can be measured by the colorimetric method for gossypol involving reaction with aniline. Subsequently, 317 glandless progenies from glandless strains crossed with derivatives of Texas 27, Texas 194 and Texas 254 were assayed for their effect on larval growth. None of the glandless selections tested caused a reduction in larval growth compared with insects feeding on a casein‐wheat germ diet, which suggest that the X‐factor effect results from one of the following: 1) gossypol; 2) synergist or additive effects of gossypol and other toxic compounds in flowerbuds; 3) gossypol‐related compound that gives the same colorimetric test as gossypol but is more toxic than gossypol. Some of the glanded sister lines from the crosses suppressed larval weight by more than 50%, but generally this reduction was within the confidence limits of the reduction expected fxom gossypol content.
Parent‐Progeny Regression in Indiangrass: Inflation of Heritability Estimates by Environmental Covariances1
Authors: Vogel K. P. , Haskins F. A. , Gorz H. J.
Published: July 2010

Families of two indiangrass [Sorghastrum nutans (L.) Nash] populations were used in this study with a family plot consisting of a parental clone and four half‐sib progeny. The experimental design was a randomized complete block with two replications. The regression of offspring on the parent in the same plot was used to obtain heritability estimates in which environmental covariances might be expected to inflate the parent‐offspring covariance. The regression of offspring in one replication with its parent in another replication, and vice versa, was used to obtain heritability estimates whereby environmental covariances should be minimized. Heritability estimates for heading date and plant height, which had high heritabilities, were similar for the two estimation techniques. Heritability estimates for forage yield and in vitro dry matter digestibility (IVDMD) appeared to be influenced by environmental covariances. Mean heritability estimates for forage yield and IVDMD for the three sets of data analyzed were 0.64 and 0.94 respectively, when parents and offspring in the same plot were used in the regression analyses and 0.28 and 0.42 respectively, when parents and offspring in different plots were used. Heritability estimates for forage protein content averaged 0.49 and were similar for both methods of estimation.
Long‐term Progress Made by Cotton Breeders in Developing Fusarium Wilt Resistant Germplasm1
Authors: Kappelman A. J.
Published: July 2010

Breeding for resistance in cotton, Gossypium hirsutum L, to fusarium wilt, Fusarium oxysporum Schlect. f. vasinfectum (Ark.) Synd. & Hans., began shortly after the causal agent was described in 1892 and continues. Many cultivars and advanced breeding stocks having resistance are deficient in agronomic and fiber characteristics or properties present in less resistant stocks, Breeding stocks and cultivars submitted annually hy 11 cooperators from 1969 to 1978 were evaluated for wilt resistance by growing them on a soil highly infested with both the wilt organism and root‐knot nematodes, Meloidogyne incognita acrita (Chitwood & Oteifa). The relative mean wilting percentages of all entries evaluated during the last 3 years of this test were significantly less than wilting percentages of those evaluated at the beginning of the test period. These results indicate that progress has been made in breeding for fusarium wilt resistance. The rate of progress in combining acceptable agronomic properties and fusarium wilt resistance into commercial cultivars also increased in the last 3 years of the test.
Disease Resistance and Yield Loss to Sugarcane Mosaic Virus in East African‐adapted Maize1
Authors: Louie Raymond , Darrah L. L.
Published: July 2010

Maize (Zea mays L.) inbreds, cultivars, and hybrids were tested for resistance to two Kenya isolates of sugarcane mosaic virus (SCMV‐Kit and SCMV‐Mug). Sixteen out of 4,380 plants representing 8 of 71 entries were resistant. Five S1 plants from field selections continued to demonstrate resistance to SCMV. S2 plants from Philippine DMR‐5 mechanically inoculated with SCMV‐Kit and SCMV‐Mug appeared highly resistant or tolerant. Pa405, a U.S.‐adapted inbred, was also resistant to SCMV‐Kit and SCMV‐Mug.

When mechanically inoculated with SCMV‐Kit, 10 Kenyan hybrids had yield losses that varied from 18 to 46%. Yield losses varied significantly by hybrid but not tune of inoculation. The interaction of hybrid X time of inoculation was not significant for yield. Tolerant hybrids, such as H614C, H611(R)C5, H612C, H5020, or EAH6302, are recommended in areas of East Africa where SCMV is prevalent.
Comparison of Gains Predicted by Several Selection Methods for Cold Tolerance Traits of Two Maize Populations1
Authors: Crosbie T. M. , Mock J. J. , Smith O. S.
Published: July 2010

Index selection was developed to help breeders practice simultaneous selection for several traits. Our objective was to compare selection differentials, expected gains, and relative index efficiencies of several indexes constructed to improve cold tolerance of two maize (Zea mays L.) populations. Cold tolerance traits were percentage emergence, emergence index (i.e., rate of emergence), and seedling dry weight.

Best predicted results for all traits were given by a rank summation index, a multiplicative, weight‐free index, and a base index (index weights were reciprocals of phenotypic standard deviations). These indexes were not seriously affected by unequal variances among traits and combined 1) simplicity of use, 2) freedom from need to estimate genetic parameters, and 3) good selection differentials and predicted gains in each trait and in the aggregate genotype. Our results also showed that selection for dry weight/plot identified lines with excellent percentage emergence and seedling dry weight.
Mutagenic Effects of Sodium Azide in Rice1
Authors: Awan M. Afsar , Konzak C. F. , Rutger J. N. , Nilan R. A.
Published: July 2010

Seeds of rice (Oryza sativa L. spp. japonica) cultivar ‘M5’ were presoaked in distilled water and treated for 2 or 3 hours with 0, 0.12, 0.50, 0.75, 1.0, 1.25, 1.50, and 1.75 mM sodium azide solutions prepared in 0.1 M phosphate buffer (pH 3). After treatment the seeds were rinsed for 1 hour in 15 C tap water. Seeds receiving a 2‐hour azide treatment were redried in a fume hood at room temperature for 24, 48, 72, and 96 hours prior to planting to develop treatment procedures suitable for transporting dry, treated seeds rather than growing seedlings. Although the scope of this study did not permit field evaluation of the redried treated seeds, it was found that seeds treated for 2 hours with I mM azide and redried for 96 hours had more injury than seeds treated for 3 hours with I mM azide without redrying. Thus, a 1 mM azide treatment for 2 hours with redrying may be near the maximum permissible for sufficient field viability of the M1. Seeds with a 3‐hour azide treatment were planted immediately after rinsing. The seedlings were transported by air to the California test site and transplanted for the mutation study.

Criteria used to assess the biological effects of azide on rice were germination, seedling height, and seed sterility in the M1 generation, and chlorophyll‐deficient seedlings and viable mutations in the M2 generation.

In general, an increase in azide concentration, along with an increase in the post‐treatment redrying period, resulted in a decrease in M1 germination and seedling height. Azide treatment also induced sterility, the highest concentration producing maximum (62.2%) seed sterility. The same treatment induced chlorophyll mutations in 98.5% of the M1 panicle progenies and in 14% of the M2 seedlings. The viridis type of mutation was most frequent.

The highest frequency of viable mutations scored in the adult plant stage was 4.64% on an M2 plant basis. All azide concentrations were mutagenic. Short‐culm and dwarf mutant types were more frequent than the early‐flowering mutant types in the azide‐induced mutation spectrum. Azide should prove useful as a mutagen for the genetics and practical breeding of rice.
Growth and Yield of Wheat under CO2 Enrichment and Water Stress1
Authors: Sionit Nasser , Hellmers H. , Strain B. R.
Published: July 2010

Growth and yield responses of a semi‐dwarf spring wheat (Triticum aestivum L.; cv. GWO 1809) to two CO2 concentrations and two water stress regimes were studied in controlled environment chambers of the Duke Univ. Phytotron. Groups of plants in low (350 ppm), or high (1,000 ppm) CO2 environments were subjected to water stress By withholding irrigation starting at the 10th day after the beginning of anthesis. A second drying cycle beginning 5 days after termination of the first cycle was also given to some of the plants. Water potential of the flag leaves of the main stem of the plants in each CO2 environment reached a minimum of −13 bars at the end of the first drying cycle and −17 bars at the end of the second cycle.

Under well‐watered conditions high CO2 enhanced the rate of tiller production by 43% and significantly increased grain yield, total dry matter, and number and size of the grains.

As water stress developed, the osmotic potentials of the high CO2. plants decreased at a faster rate and resulted in maintenance of higher turgor pressures at the end of each stress cycle compared to the low CO2 plants. Osmotic potentials of the leaves of both high and low 2 plants decreased faster in the second drying cycle than in the first.

Significantly fewer and smaller grains were produced on the plants grown under water stress in both CO2 concentrations compared to unstressed plants. In general, high CO2 plants under water stress conditions had a grain yield and total dry matter production equal to the unstressed, low CO2 plants. Thus, CO2 enrichment increased the yield potential of the water limited wheat plants due probably to osmotic adjustment by an increased concentration of solutes in their leaves.
Selection for Root and Crown Rot Resistance in Alfalfa1
Authors: Richard C. , Michaud R. , Frève A. , Gagnon C.
Published: July 2010

Root and orown rot cause extensive damage to alfalfa (Medicago sativa). In this study, Fusorium solani followed by F. oxysporum, F. roseum, and F. tricinctum were most frequently isolated.

Two techniques of inoculation, with one isolate of F. roseum var. acuminatum, were used for screening alfalfa for Fusarium root rot resistance. Both techniques were effective in producing a high percentage of infection. The application technique used on 3‐month‐old plants gave 5.9% resistant plants in the cultivar ‘Europa.’ Only 3.2% resistant plants were found when the bareroot‐soak technique was applied on 3‐week‐old seedlings. Resistance was evaluated by measuring the vertical discoloration in the split taproot. Plants with less than a 5mm spread of internal browning from the wound site were saved and intercrossed.

The populations developed through each technique were established in the field at three locations in the spring of 1977 and rated for root rot in the fall of 1978. The two populations selected for resistance showed consistently less root rot than the unselected one although differences were not statistically significant.

In a greenhouse study we were able to detect significant variation for root rot infection among as well as within polyerossed progenies of the selected genotypes suggesting that resistant genes for this disease are present in alfalfa. Narrow‐sense heritability was estimated at 22%. Some specific crosses were made between resistant (R) and susceptible (S) plants. The cross S ✕ S showed almost twice as much root rot infection as the cross R ✕ R. R ✕ S was better than expected based on mid value of R ✕ R and S ✕ S.

Based on the results of this study, we believe progress is possible toward developing a crown and root rot resistant alfalfa.
Major Gene Control of Nitrate Reductase Activity in Common Wheat1
Authors: Gallagher L. W. , Soliman K. M. , Qualset C. O. , Huffaker R. C. , Rains D. W.
Published: July 2010

Two high‐yielding, short‐statured spring wheats (Triticum aestivum L.), ‘Anza’ and ‘UC 44‐111,’ differ in certain characteristics of N metabolism. Nitrate reductase activity (NRA), measured in vitro on shoots or lamina of seedling plants, was about 8 and 18 µmoles of nitriteproduced/hour/g fresh weight for Anza and UC 44‐111, respectively. The genetic basis for this difference was investigated with an in vitro NRA assay on seedling plants to determine the NRA frequency distributions of parents, F1, F2, reciprocal BCF2 and randomly derived F6 lines. All data were consistent in showing that UC 44‐111 has a single dominant gene (Nra) which accounted for most of the variability observed for NRA.
Aflatoxin in Corn before Harvest: Interaction of Hybrids and Locations1
Authors: Lilleboj E. B. , Kwolek W. F. , Zuber M. S. , Bockholt A. J. , Calvert O. H. , Findley W. R. , Guthrie W. D. , Horner E. S. , Josephson L. M. , King S. , Manwiller A. , Sauer D. B. , Thompson D. , Turner M. , Widstrom N. W.
Published: July 2010

Twelve corn (Zea mays L.) hybrids, including one reciprocal, with differences in trypsin inhibitor levels and insect resistance were grown during 1978 at 12 locations in the United States. The study examined the effect of planting date, inoculation with Aspergillus flavus Link ex Fr., and mechanical damage of developing kernels on aflatoxin accumulation in kernels before harvest. Although a broad occurrence of toxin was found in kernels of untreated ears from locations outside the Corn Belt, addition of A. flavus spores to silks markedly increased toxin accumulation. To a lesser extent, mechanical damage was also associated with elevated aflatoxin concert. trations. At specific locations, toxin levels varied among hybrids, but no consistent interlocation pattern of absolute toxin resistance was detected. Visual insect damage on mature ears was not linked quantitatively to toxin levels. More than 90% of the Georgia, Mississippi, Missouri, North Carolina, South Carolina, and Tennessee samples had detectable aflatoxin, but less than 30% of the samples from Illinois, Iowa, and Ohio were toxin positive. In general, bright greenish‐yellow (BGY) fluores. cence in kernels and high levels of toxin were observed, but a number of samples with low levels of toxin did not exhibit the fluorescence.
Effect of 2,4‐D on Cotton Yield, Floral Nectar, Seed Germination, and Honeybee Visits
Authors: Moffett Joseph O. , Stith Lee S. , Morton Howard L. , Shipman Charles W.
Published: July 2010

In Arizona honey bees, Apis mellifera L., frequently visit cotton flowers, Gossypium hirsutum L., in sufficient numbers to adequately pollinate the male sterile flowers and produce hybrid cotton seed. Yet in some other states and at times in Arizona, honey bee visits to cotton flowers are low or erratic. Since hybrid cotton seed may be in demand in the near future, this study was made to determine how spraying 2,4‐D [(2,4‐dichlorophenoxy) acetic acid] on cotton plants affected honey bee visits, seed yields, and nectar secretion.

Small concentrations of 2,4‐D were sprayed on five cotton cultivars at three locations in Arizona from 1975 to 1977. Each year, 1 ppm applied in 187 liters of water/ ha at the beginning of bloom increased the volume of floral nectar more than 30%. An application of 10 ppm was harmful to the plants. Application of 2,4‐D when plants started to flower increased the amount of nectar more than application 3 weeks earlier or application at both times. One ppm of 2,4‐D had no significant effect on cotton yields or sugar concentration of the floral nectar.This dosage also had no significant effect on honey bee visits during the only year, 1977, that visits were counted. However, this year the visits were relatively high in both the check and unsprayed plots. Results might be different when the bees are not visiting the flowers well. None of the levels of 2,4‐D applied (0.01, 0.1, 1.0, and 10.0 ppm) affected germination or weight of the seeds produced or caused damage to seedlings grown from the sprayed plants.
Population Variability in the Reaction of Alfalfa to Alfalfa Bud Mite1
Authors: Ridland P. M. , Halloran G. M.
Published: July 2010

Variability in the reaction of alfalfa (Medicago sotiva L.) seedlings to infestation with alfalfa bud mite (Eriophyes medicaginis Keifer) was studied in the Australian cultivar ‘Hunter River.’ Plants were harvested 23 days after infestation and leaf symptoms classed as severe, moderate or mild. Severity was not related to the total mite population but rather to the distribution of the mites on the plant. The seedlings least affected by mite infestation were those that had the lowest number of axillary shoots and the highest rate of growth of the primary shoot. Selection for greater seedling vigour within this cultivar could increase tolerance to the mite. However, tolerance of seedlings to mite attack may not be related directly to tolerance in older plants.
A Compendium of Information about Named Genes for Low Reaction to Puccinia recondita in Wheat1
Authors: Browder L. E.
Published: July 2010

Thirty‐five genes for low reaction to Puccinia recondita Rob. ex Desm. (Lr genes) in wheat, Triticum aestivum L., have been studied and named in a sequential number series by different authors. This paper summarizes information about these named Lr genes. Information on origin, chromosome location, characteristic low infection types, relative environmental sensitivity, synonymy, reference host lines, and reference cultures is summarized.

Five Lr genes, Lrl2, Lrl3, Lr22a, Lr22b, and Lr26 can be detected only by inoculating adult plants with an avirulent culture; the others can be detected by inoculating seedling plants with an appropriate cullture. Characteristic low infection types conditioned by Lr genes and their corresponding Lr genes range from 01C, where only very small flecks occur, to 56X to 78X where extensive sporulation occurs. Post‐infection Temperature influences the expression of all Lr genes; but some, Lr11, Lr12. Lr13, Lrl4a, and Lrl8 are especially sensitive to high temperatures. The name Lr genes have been shown to occur on 13 different chromosomes, in all 3 common wheat genomes. Lr genes and their corresponding genes for pathogenicity are the basis for storing and retrieving information about specificity in the P. recondita:Triticum system.
Host‐Pathogen Variability for Fusarium‐Caused Root Rot in Red Clover1
Authors: Pederson G. A. , Hill R. R. , Leath K. T.
Published: July 2010

Progenies from diallel crosses in red clover (Trifolium pratense L. cv. Arlington) were evaluated for reaction to four isolates of Fusarium roseum (Lk.) emend Snyd. and Hans. General combining ability effects were significant for length of rotted root after inoculation with F. roseum. Genetic effects other than general combining ability were not significant. Root rot tended to be more severe in plants with large than in those with small root diameters. Estimate of the isolate by host‐genotype interaction variances were not significant, but different ranking of the parental means with isolates was observed. The heritability estimate for root rot severity was low (0.075). Our results indicate that selection for root rot resistance should be done by evaluation of progenies in replicated designs in which two or more virulent isolates of F. roseum are used.
Effect of the Ethoxy Analog of Rhizobitoxine on Nodulation of Soybeans1
Authors: Devine T. E. , Breithaupt B. H.
Published: July 2010

A common property of Rhizobium japonicum strains that are able to nodulate the nodulation restrictive soybean [Glycine max (L.) Merr.] genotype rj1 rj1 is the ability to produce rhizobitoxine (2‐amino‐3‐hydroxypropoxyvinylglycine). The ethoxy analog of rhizobitoxine (aminoethoxyvinylglycine) was tested for potential to modify the nodulating ability of strains of Rhizobium japonicum (Kirchner) Buchanan with Clark rj1rj1 soybeans. The analog was added to broth cultures of Rhizobium at concentrations of 0, 5 ✕ lO−10, 5 ✕ 10−8, 5 ✕ 10−6, 5 ✕ 10−6 and 5 ✕ 10−4 M, 30 hours before being used to inoculate seeds planted in Leonard jars.

The analog did not enhance nodulation at any of the concentrations tested. Genetic modification of the rhizobial microsymbiont appears to be a more promising approach for obtaining Rhizobium strains capable of successfully nodulating the rj1 rj1 genotype.
Effect of Awn Length and Naked Caryopsis on Malting Quality of Betzes Barley1
Authors: McGuire Charles F. , Hockett E. A.
Published: July 2010

Plant breeders at the Montana Agruicultural Experiment Station developed four isogenic ‘Betzes’ lines from a Betzes*7/‘Sermo’ barley (Hordeum vulgare L.) cross. The four isogenes were long‐awned covered (Lk2Lk2NN), long‐awned naked (Lk2Lk2nn) short‐awned covered (lk2lk2NN), and short‐awned naked (lk2lk2nn). These lines and Betzes were grown in a total of 11 environments in the western United States in 1970 and 1973.

Of the four experimental isogenic lines, the two covered types produced the most grain and were similar to Betzes in this trait. The long‐awned naked line produced 91%, and the short‐awned naked 89%, of Betzes. Grain from each location was malted separately. Long awns produced significantly heavier kernels, higher percentage of plump kernels, lower diastatic power, and lower alpha amylase activity than short awns. Naked caryopsis conditioned significantly higher barley protein content, higher malt extract, a higher finecoarse grind extract difference, lower kernel weight, lower percentage of plump kernels, lower kernel color score, lower wort color, lower wort N:malt N, lower diastatic power, and lower alpha amylase activity than the covered caryopsis. Genotypes with the covered allele averaged about 10% greater grain yield than did the naked genotypes.
Recurrent Selection in Soybeans. III. Selection for Increased Percent Oil in Seeds1
Authors: Burton J. W. , Brim C. A.
Published: July 2010

Three cycles of recurrent selection to increase seed oil percentage were conducted in a soybean [Glycine max (L.) Merr.] population segregating for male sterility (ms1ms1). The base population was planted single plant hills to allow for natural cross pollination of male‐sterile plants by male‐fertile plants. At maturity, male‐sterile plants with the highest seed oil percentages were selected from this crossing block. The halfsib families from the selected plants w.ere grown to maturity in the greenhouse, and the individual within each half‐sib family with the highest seed oil percentage was selected. A new cycle was begun by a natural intermating of the progeny of theselected individuals in the field.

The selected progenies from each cycle of selection were evaluated in composite populations and singly as lines. The combined composite and lines tests showed cycles of selection, at an average rate of 0.35 ± 0.03/cycle. There was a nonsignificant increase in total oil from 444 to 460 kg/ha. Protein percentage decreased at a rate of −0.52 ± 0.08/cycle. Changes in yield and total protein were not statistically significant.

An investigation of variation within the selection populations showed that genotypic variation among the mass selected lines did not change through three cycles of selection. Variation among the within half‐sib family selected lines was greater than the variation among mass selected lines in cycle one and two but not three. Realized heritability estimated from the observed response to mass selection was 0.28 ± 0.03, and the heritability estimated from the within family selection response was 0.20 ± 0.04. The difference between the two was attributed, in part, to differences in phenotypic variance.

The results showed that both mass and within family selection contributed to the overall progress. The segregation of genetic male sterility in the population proved to be a convenient and inexpensive way to allow natural random mating of selected individuals and to provide half‐sib families.