bluuebunny/crossref_metadata_2025_split 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.
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.
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.
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.