bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetics of Cell Size and Sucrose Concentration in Sugarbeet1
Authors: Doney Devon L. , Theurer J. Clair
Published: July 2010

Sugarbeet (Beta vulgaris L.) root cell size has been shown to be negatively correlated with sucrose concentration. This study was initiated to determine the genetics of sugarbeet root cell size and sucrose concentration and their inheritance relationships. Inheritance was studied in 1) inbred parents and hybrids of five males crossed to the same female, 2) a three‐by‐three males ✕ females crossing system, and 3) a five‐by‐five diallel cross, which included parent inbreds but not reciprocals. Sucrose concentrations were determined in replicated field trials, whereas cell diameters were measured microscopically from stained root cross sections of 21‐ and 28‐day‐old seedlings. Midparent heterosis, general and specific combining ability, and genetic variances were calculated. Cell diameter and sucrose concentration exhibited little midparent heterosis. General combining ability was significant at P = 0.01 for cell diameter and sucrose concentration. Specific combining ability was nonsignificant in one test for both cell diameter and sucrose concentration and significant at P = 0.05 for cell diameter and at P = 0.01 for sucrose concentration in the other test. Of the total genetic variance, additive genetic variance accounted for 80 and 91% for cell diameter and 72 and 90% for sucrose concentration in two respective sets of hybrid crosses. The significant negative correlation between cell diameter and sucrose concentration and their apparently similar inheritance patterns suggest that the additive genes affecting cell diameter (cell size) may be the same genes responsible for the additive genetic variance of sucrose concentration. There are, however, some notable exceptions to the above relationships, and it must be recognized that other genes not related to cell size also affect sucrose concentration.
Genetic Analysis of a Null‐Allele for Lipoxygenase‐3 in Soybean Seeds1
Authors: Kitamura K. , Davies C. S. , Kaizuma N. , Nielsen N. C.
Published: July 2010

This study describes a major gene which controls lipoxygenase‐3 (L‐3) activity in soybean [Glycine max (L.) Merr.]. Cultlvars ‘Wasenatsu’ (PI 417 458) and ‘Ichigowase’ (PI 205 085) were found to L‐3 by both immunological and electrophoretic methods. The inheritance of this trait was determined from progeny of crosses between Wasenatsu and either ‘Century’ or ‘Raiden’, two cultlvars that contain high levels of L‐3. Segregation ratios in F2 and F3 seeds from selfed plants indicated that absence of L‐3 was due to a single allele that was recessive to the one controlling the presence of the enzyme. Comparable results have been obtained using progeny from the cross Ichigowase ✕ PI 408 251. The latter parent contains L‐3 but lacks L‐1. We propose that the dominant allele be called Lx3, whereas the recessive one be designated lx3.
Inheritance of Photosensitivity in Maize1
Authors: Russell W. K. , Stuber C. W.
Published: July 2010

Sensitivity of maturity in maize (Zea mays L.) to photoperiod restricts exchange of germplasm across latitude. To investigate the inheritance of this trait, the differences in photosensitivity between B68 and Tx61M (Exp. 1) and between C3 and Tx601 (Exp. 2) were investigated using total leaf number as a measure of maturity. In Exp. 1, the expected long‐day responses were not observed in two North Carolina environments. In a phytotron environment, both B68 and Tx61M exhibited significant photosensitivity; however, Tx61M, which averaged 7.6 more leaves under the longer photoperiod, was four times more sensitive than B68. In Exp. 2, evaluations were conducted in Florida (fall planting), North Carolina (spring planting), and under short‐day and long‐day photoperiods in a phytotron. Tx601 produced 4.4 more leaves in North Carolina than in Florida, and this was thought to be a photoperiodic response. An even greater photosensitivity was exhibited by Tx601 in the phytotron. A primary objective in Exp. 2 was to determine if photosensitivity in maize is simply inherited. An evaluation of the distribution of backcross‐derived lines was unsuccessful in resolving this issue. In both experiments a generation mean analysis indicated a preponderance of additive gene action.
Seedling Characteristics and Rates of Seed Reserve Utilization of Wilman Lovegrass and Kleingrass1
Authors: Tischler C. R. , Voigt P. W.
Published: July 2010

The objective of this study was to determine why wilman lovegrass (Eragrostis superba Peyr.) has a greater shoot mass (P < 0.01) at 14 days postemergence than does kleingrass (Panicum coloratum L.). Caryopses of both species contain the same amount of starch, but wilman lovegrass caryopses contain more protein and P (P < 0.01). Wilman lovegrass had a greater shoot mass than kleingrass at 3 and 7 days postemergence. At 3 days after germination, wilman lovegrass caryopses contained less starch (P < 0.05) than kleingrass. At 6 days after planting, starch reserves were depleted in both species and protein and P contents of the caryopses residues were similar in both species, thus indicating the wilman lovegrass caryopses supplied more protein (or amino acids) and P to the growing shoot than did corresponding kleingrass caryopses. Respiration rates of caryopses of both grasses were similar after 1 day of imbibition, but respiration rates of 2‐ and 3‐day‐old wilman lovegrass seedlings were higher (P < 0.05) than rates of corresponding kleingrass seedlings. Wilman lovegrass had a greater nitrate reductase activity than kleingrass at 3 days after emergence (P < 0.05), although nitrite reductase activity and chlorophyll content were similar in both species. Selection for greater seedling vigor in kleingrass may result in genotypes with a) a faster rate of starch mobilization and utilization, and b) a higher starch, protein, and P content per caryopsis.
Genotype ✕ Environment Interaction of Cottons Varying in Insect Resistance1
Authors: McCarty J. C. , Meredith W. R. , Jenkins J. N. , Parrott W. L. , Bailey J. C.
Published: July 2010

Insect resistance and glandless traits were introgressed, usually by the backcross method, into agronomically acceptable genetic backgrounds of cotton, Gossypium hirsutum L. The yield potential and adaptability of nine nectariless‐nectaried pairs of cottons were evaluated for 1 to 3 years, 1978 to 1980, at six locations with and without early season insect control. Five of these pairs were in conventional Coker, Deltapine, Stoneville, or DES genetic backgrounds. The others were backcross‐derived strains that combined nectaried or nectariless with the frego bract, Okra leaf, Smooth leaf, high gossypol, or glandless traits. Significant strain ✕ location interactions were detected for first harvest (earliness) and total lint yields. Nectariless cottons had significantly higher first harvest yields than nectaried ones in 1978 and 1979. Over 3 years, nectariless cottons averaged 5.7% higher total yields than nectaried cottons, 887 vs. 827 kg/ha, respectively when grown without early season insect control. However, no differences in total yield were detected between the nectaried/nectariless cottons when grown with early season insect control. The environmental index used for the 18 environments studied was determined by the average performance of two nectaried cottons, ‘Stoneville 213’ and ‘Deltapine 61’, and two nectariless ones, ‘Stoneville 825’ and Deltapine 7146N. The average regression coefficient for the nectariless cottons was not different from the nectaried ones (b = 0.81 vs. b = 0.79, respectively) when grown with early season insect control. However, when grown without early season control the average regression coefficient for nectariless was significantly higher than nectaried ones (b = 0.86 vs. b = 0.76, respectively). The average regression coefficient, with and without early season insect control, for the glandless, high gossypol, Okra leaf, and frego bract traits were 0.64, 0.70, 0.76, and 0.43, respectively. This study suggests that the nectariless cottons used had high adaptability potentials, but the other traits investigated did not.
Differential Nucleo‐Cytoplasmic Interactions Involving Aegilops longissima Cytoplasm and Nuclei of Emmer and Common Wheat1
Authors: Maan S. S.
Published: July 2010

Previous attempts to substitute euploid nuclei of Triticum durum Desf. and T. aestivum L. into the cytoplasm of Aegilops longissima S. & M. failed because one alien chromosome always remained fixed in the wheat nucleus. However, the alien chromosome was absent or the action of the gene(s) on this chromosome was modified in an exceptional progeny after eight backcrosses (BC8) to T. durum which contained four exceptional 29‐chromosome male‐sterile plants with 14”+1’. In BC9 and BC10 generations, these plants produced a small number of viable seeds, and 29‐chromosome plants of material constitution were obtained. In this study, these plants were used as the cytoplasmic source to develop alloplasmic euploid T. aestivum with Ae. longissima cytoplasm. However, euploid T. durum with Ae. longissima cytoplasm was not obtained either from the use of these alloplasmic T. aestivum plants or from F1 hybrids of 29‐chromosome plants ✕ euploid T. aestivum. Both sets of progenies from backcrosses with T. durum as the recurrent male parent, contained all 29‐chromosome plants, where the Ae. longissima chromosome was replaced by one D‐genome chromosome from T. aestivum. Like the Ae. longissima chromosome, this D‐genome was also maternally transmitted to all viable progeny. Thus, one chromosome of Ae. longissima or a D‐genome chromosome from T. aestivum was essential to have viable T. durum plants with Ae. longissima cytoplasm, even though euploid T. aestivum with Ae. longissima cytoplasm had normal fertility and plant vigor. These results show that euploid nuclei of T. durum and T. aestivum have differential interactions with the cytoplasm Ae. longissima. Therefore, Ae. longissima is cytoplasmically different from the emmer and common wheats, and Ae. longissima may not be the diploid B‐genome progenitor of emmer wheats.
Morphological Stage of Development as a Predictor of Alfalfa Herbage Quality1
Authors: Kalu Bernard A. , Fick Gary W.
Published: July 2010

Variations in the nutritive value of herbage are related to the environmental and physiological history of the crop. Previous work indicated that a precise and quantitative method for specifying morphological stage of development in alfalfa (Medicago sativa L.) is a good basis for predicting alfalfa herbage quality. The purpose of this study was to test the consistency of the stage rating system as a predictor of crude protein (CP), in vitro true digestibility (IVTD), neutral detergent fiber (NDF), acid detergent fiber (ADF), and lignin in alfalfa herbage. The field study was conducted over 3 years and with three stand ages and two soil types (Typic Fragiochrept and Aqueptic Fragiudalf). Sequential harvesting was used to establish plots varying in herbage age and stage at common points in time. The 10‐stage classification system that was used included three vegetative, two bud, two flowering, and three seed‐pod stages. The system was tested by relating individual stages to herbage quality. There was a consistent pattern of quality change among stages, but absolute values differed for each year and age. The mean stage of an herbage sample (MSW) was calculated as the average of the stages of the individual shoots present weighted for the dry weight contributed by each stage. In all cases, MSW consistently provided highly significant linear or quadratic relationships for predicting herbage quality: CP (R2 = 0.883), IVTD (r2 = 0.957), NDF (R2 = 0.946), ADF (r2 = 0.899), lignin (r2 = 0.841). These relationships verified the practical applicability of the MSW procedure for predicting alfalfa herbage quality.
Significance of Accelerated Leaf Senescence at Low Water Potentials for Water Loss and Grain Yield in Maize1
Authors: Aparicio‐Tejo Pedro , Boyer John. S.
Published: July 2010

Productivity is lost when plants are subjected to dry soil conditions and this loss is often accompanied by the senescence of leaf tissue. The role of leaf senescence in water conservation and grain production was therefore evaluated in maize (Zea mays L.) subjected to low water potentials for most of the grain filling period. The plants were grown in soil in controlled environment chambers and water was withheld from the soil after pollination had occurred. Low leaf water potentials were maintained for 30 days (until the grain matured) by daily addition of small amounts of water to the soil. The low water potentials (−1.8 to −2.0 MPa) inhibited dry matter accumulation and transpiration by the plants. However, in addition to the initial inhibition of transpiration by stomatal closure, there was a further inhibition (about 11% of the control rate) associated with accelerated senescence of the leaves. Excision of senesced leaf tissue showed that, despite this inhibition of water loss attributable to senescence, the dead tissue itself continued to lose a small amount of water while attached to the plants. Although the low water potentials were of long enough duration to allow significant acclimation of the plants, the senescing tissue contributed only a small amount of dry matter to the grain by mobilizing leaf constituents. Since the amount of water conserved by the senescing tissue was also small, it is likely that accelerated leaf senescence contributes little to grain production at low water potentials and has the disadvantage that it sacrifices potential photosynthetic surface. Therefore, selection against accelerated senescence of leaves at low water potentials may be desirable for crops.
Response to Selection for Leaf Area Expansion Rate of Tall Fescue1
Authors: Reeder L. R. , Sleper D. A. , Nelson C. J.
Published: July 2010

Development of effective selection criteria for the improvement of dry matter yield is a desirable goal in forage grass breeding. Leaf area expansion rate (LAER) has been suggested as acceptable selection criterion for improving post‐flowering yield of tall fescue (Festuca arundinacea Schreb.). Our objectives were to evaluate the responses of LAER, and its components leaf elongation rate (LER) and leaf width (WID) to five cycles recurrent phenotypic selection for both high and low LAER. In August 1980, a representative Co population, parents and offspring of the third and fifth cycles of selection for high and low LAER, and the check cultivars Missouri 96 and Kentucky 31 were transplanted into a field experiment. One tiller on 40 plants of each entry was evaluated in the fall of 1980 and 1981 for LER, WID, and LAER. Linear regression of performance on cycle of selection predicted an increase in LER of 0.87 and 0.48 mm/day/cycle of selection for high LAER in 1980 and 1981, respectively, while selection for low LAER resulted in a predicted decrease in LER of 0.77 and 0.84 mm/day/cycle of selection in 1980 and 1981, respectively. Predicted increase of WID was 0.45 and 0.33 mm/cycle in 1980 and 1981, respectively. Response of LAER to selection for high LAER in 1980 and 1981 was an increase of 15.7 and 10.8 mm2/day/cycle of selection, respectively, while selection for low LAER caused LAER to decrease by 11.6 mm2/day/cycle of selection in 1980 and 10.5 mm2/day/cycle in 1981. In both years, the responses of LER, WlD, and LAER to divergent selection for LAER were largely linear and symmetric. Thus, gene action for LAER and its components is additive in large part, and it is likely that continued response to selection would be realized in additional cycles.
Effects of Brown Midrib‐3 on Yields and Yield Components of Maize1
Authors: Lee Myoung Hoon , Brewbaker J. L.
Published: July 2010

The brown midrib‐3 (bm3) gene associated with low lignin in corn (Zea mays L.) was evaluated for its effects on yield and yield components in Hawaii. Fifteen bm3 hybrids representing a sixparent diallel and their 15 isogenic normal counterpart hybrids were planted as paired rows in two trials. Yields of the bm3 hybrids were significantly lower than normals in both trials, with average reductions of 20% (range 7 to 29%) for grain and 17% (range 8 to 25%) for stover. Traits also affected negatively by bm3 included kernel number per row (−;12%), filled ear length (−10%), ear height (−7%), plant height (−5%), and five other measured traits. Correlation matrices of yields and all measured traits revealed few consistent differences among normal and bm3 hybrids. Grain yields correlated highly with leaf area index for normal hybrids, but not for the isogenic bm3 hybrids. Mean square values for general and specific combining ability (GCA, SCA) were significant for grain and stover yields and plant height, and GCA effects were significant for kernel number per row and ear length. The GCA/SCA ratios were higher for bm3 hybrids than for normals for grain and stover yield. The gains in stover digestibility of bm3 through lowered lignin content did not offset yield losses enough to justify separate breeding programs with bm3. Linkage of the bm3 gene with yield‐reducing genes was virtually excluded in this study as a cause for the yield reduction, and a role of colored lignins in reducing photosynthates is postulated.
Partitioning the Genetic Variability for Seedling Growth in Sand Bluestem into Its Seed Size and Seedling Vigor Components1
Authors: Glewen K. L. , Vogel K. P.
Published: July 2010

Spaced plants of ‘Goldstrike’ sand bluestem (Andropogon hallii Hack.) were used to obtain estimates of the genetic variances for caryopsis weight, seedling weight at 8 weeks which was used as a measure of seedling growth, and 1st year forage yields. Since caryopsis weight has a positive effect on seedling weight, seedling weights were adjusted for caryopsis weight using regression analyses. Adjusted seedling weights are a measure of seedling growth with the effect of seed size excluded and as such were used as an estimate of seedling vigor. Heritability estimates were calculated using variance components. The broad‐sense heritability estimate for caryopsis weight was 0.87 while the narrowsense heritability estimates for seedling weight, adjusted seedling weight (seedling vigor), and 1st year forage yield were 0.37, 0.22, and 0.63, respectively. As indicated by the heritability estimates, almost half of the genetic variability for seedling weight was due to variation for caryopsis weight while the remaining genetic variability was due to seedling vigor. The genetic correlation of caryopsis weight and seedling weight was 0.70. Selection for seedling weight by indirect selection for caryopsis weight would result in expected gains from selection almost as large as those for direct selection for seedling weight. However, the genotypes selected by the two methods would not be identical. Selection for seedling weight involves selection for both seed weight and seedling vigor and should optimize breeding gains for improved seedling vigor. The correlations of caryopsis weight and seedling weight with post‐establishment 1st year forage yield were small (r ≤ 0.15).
Locating the w1 Locus on the Satellite Chromosome in Soybean1
Authors: Sadanaga K. , Grindeland R. L.
Published: July 2010

F2 data of field‐grown plants of a cross between translocation 172‐11‐3 (purple flower, W1) and type collection line T93A (white flower, w1) of soybean [Glycine max (L.) Merr.] revealed a significant deviation from the expected ratio of 3 purple: 1 white. To determine the cause(s) of the abnormal ratio, the chromosome number and constitution of the F2 progenies of another cross involving 172‐11‐3 and T161 (white flower) were determined. Translocation 172‐11‐3 has cytologically recognizable interchange chromosomes, and the short interchange chromosome was present as a univalent in 46% of the pollen mother cells (PMCs) in interchange heterozygotes. Sixty‐five percent of the F2 progeny were disomics of the N/N, N/T, and T/T types, 18% were trisomics, 16% were 40‐chromosome plants with a duplication‐deficiency gamete, and 1% were 42‐chromosome plants. Assuming that the univalent was lost in the cytoplasm 50% of the time, the observed number of N/N and N/T plants fit the expected, but the number of T/T did not. A recombination frequency of 1.9% between w1 and the breakpoint was calculated. The F2 data of duplex trisomic hybrids indicated that the w1 locus was on the satellite chromosome. The breakpoint on the long arm of the satellite chromosome is distal to the w1 locus. Our data indicated no linkage between the breakpoint and the genes y10 (chlorophyll deficiency) and t (pubescence color).
Inheritance of Resistance to Southern Corn Rust in Maize Populations1
Authors: Scott Gene E. , King Stanley B. , Armour Joe W.
Published: July 2010

To obtain information on the type of gene action and number of genes for resistance to Puccinia polysora Underw. in a number of corn (Zea mays L.) populations, we evaluated F2 progenies from crosses between homozygous resistant selections and a common susceptible tester. In other studies with resistant selections, we conducted allele tests to determine if genes for resistance were at the Rpp9 locus. Analysis of our data indicated that either a one or two gene model would explain the F2 ratios obtained. The type of gene action involved included complete, partial, or no dominance. All five selections evaluated were found to have a gene for resistance at, or very closely linked with, the Rpp9 locus.
Effect of Number of Parents and Synthetic Generation on the Performance of Self‐Incompatible and Self‐Fertile Rye Populations1
Authors: Singh R. K. , Geiger H. H. , Diener C. , Morgenstern K.
Published: July 2010

The present study was conducted to investigate the effects of number of parents and generation of multiplication on the means of rye (Secale cereale L.) synthetics developed from self‐incompatible (SS) and self‐fertile (SF) parents, and to test efficacy of Busbice' (1970) equation for predicting yields of such synthetics. Both groups of parents were random selections from the same base population. The SF synthetics were significantly inferior to the SS synthetics for both grain yield and 1000‐grain weight. Yield reductions from Syn‐2 to Syn‐3 were observed only for the SF material. In both groups, the yield and 1000‐grain weight increased with the increase in number of parents per synthetic, but only in the SS material did synthetics approach or exceed the predicted yield of the noninbred base population. The prediction based on Busbice' equation fitted well to the observed performance data. The inbreeding minimum was estimated to fall 69% below the performance level of the noninbred population for yield and 35% for 1000‐grain weight. Highly consistent estimates of the selfing rate, 0.34 for grain yield and 0.35 for 1000‐grain weight, were obtained in the SF synthetics. On the basis of these results, it may be concluded that rye SF materials are inferior to the SS in a synthetic breeding program.
Response of a Maize Synthetic to Recurrent Selection for Stalk Quality1
Authors: Martin M. J. , Russell W. A.
Published: July 2010

Recurrent selection, based on S1 lines in replicated experiments, was used in separate trials for three cycles to improve the maize (Zea mays L.) synthetic BS1 for resistance to artificial stalk rot (Diplodia maydis) and resistance to mechanical stalk breakage. The cycle populations (BS1 and C1 to C3 for BS1SR and BS1MS for stalk‐rot and stalk‐strength selection, respectively), populations crossed to a low‐stalk‐quality single cross, and crosses of populations between each procedure of selection were evaluated for stalk and rind strength, Diplodia stalk rot, field stalk rot, and field stalk and root lodging. Random S1 lines from BS1 and C3 populations of BS1SR and BS1MS were evaluated for Diplodia stalk rot and stalk and rind strength. Highly significant improvements were observed for all stalk‐quality traits. Changes from the CO to BS1MSC3 and BSISRC3, respectively, were as follows: stalk strength, 34.8 to 56.5 and 46.7 kg; Diplodia stalk‐rot rating, 3.5 to 1.8 and 1.7; rind strength, 3.4 to 4.2 and 4.3 kg; field stalk‐rotted plants, 25 to 5 and 8%; and field stalk‐lodged plants, 13 to 6 and 3%. Improvements in population crosses, population testcrosses, and random S1 lines closely paralleled the improvements in the populations per se, indicating that stalk quality is controlled primarily by additive type gene action. Highly significant correlations were observed among all stalk‐quality traits. Recurrent selection for rind strength and stalk‐rot resistance, simultaneously, may be the most desirable method of improving populations for development of inbred lines with superior field stalk quality.
A Method for Selecting Female Parents of Grain Sorghum Hybrids1
Authors: Schertz K. F. , Johnson J. W.
Published: July 2010

Potential female parents of sorghum, Sorghum bicolor (L.) Moench, hybrids are male sterilized before their combining abilities are determined. This procedure necessitates considerable time and effort before the lines can be tested for combining ability. It would be advantageous to identify the highest combining potential females before they are sterilized, thus reducing the number of lines to sterilize for final testing. Our study was organized to determine if the yields of three‐way‐cross hybrids could be used to predict the expected yields of single‐cross hybrids. Eighteen three‐way‐cross hybrids and 12 related singlecross hybrids were compared in each of 2 years. Single crosses were A‐lines ✕ R lines, and three way crosses were (A‐lines ✕ B‐lines) ✕ R‐lines. Analysis of variance indicated yield differences among hybrids and contrast analyses indicated lack of differences in most comparisons of single‐cross hybrids with three related three‐way‐cross hybrids. It was concluded that comparison of the performance of three‐way‐cross hybrids of the lines used would have effectively identified the best potential female parents of single‐cross hybrids.
Effect of Defoliation on Peanut Plant Growth1
Authors: Wilkerson G. G. , Jones J. W. , Poe S. L.
Published: July 2010

Defoliation experiments were performed in order to provide information for development of a pest management simulation model for peanuts (Arachis hypogaea L.). ‘Florunner’ peanut plants were defoliated uniformly and nonuniformly at 9, 12, and 16 weeks after planting and harvested 2, 4, or 6 weeks following treatment. All defoliations resulted in lower stem weight to length ratios, lower pod numbers and weights, and equal or higher leaf numbers and weights. Defoliation altered the normal partitioning of photosynthate between plant parts. The location of defoliation damage (either uniform throughout the canopy or confined to the outer portion of the canopy) affected plant response in that plants defoliated nonuniformly grew more leaves in the 2 weeks following treatment than those defoliated uniformly
Classification of Certain N Traits as Criteria for the Identification of Productive Maize Genotypes1
Authors: Messmer M. J. , Lambert R. J. , Hageman R. H.
Published: July 2010

In the past 30 years the increase in maize (Zea mays L.) yields has not been proportional to increased N use. The isolation of genotypes that are better able to utilize N fertilizer to produce higher grain yields would improve this relationship. The purpose of this study was to determine if maize genotypes with a higher concentration of reduced N in the leaves during the early grain‐fill period are more productive. A series of 20 S1 SSS lines developed from cycle 3 of a phenotypic recurrent selection program for high and low nitrate reductase activity (NRA) were crossed to the testers B73, H96, N28, and Mo17. The hybrids were evaluated in 1980 for NRA and total reduced N concentration (RN) in leaves at 10 and 20 days after anthesis. Based on the data, four classes of genotypes were developed: high NRAhigh RN, high NRAolow RN, low NRA‐high RN, and low NRAlow RN. The four classes were evaluated in 1981 and 1982 in replicated field trials. The initial classification of genotypes for high and low NRA or RN in 1980 was reproducible when the four classes were grown in different environments in 1981‐1982. The high RN genotypes had greater grain yields than the low RN genotypes. The low NRA genotypes also showed a yield advantage over the high NRA; however, the low NRA was associated with high RN. The low NRA‐high RN class had significantly greater yields in 1981 and 1982 than the other three classes. The high RN class compared with the low RN class had higher yields (10.5%), lower grain moisture at maturity, silked 2 days later, produced more kernels (6%) that were smaller (by weight 4%) and deposited dry matter in the grain at a faster rate (20%) from 35 days after anthesis to maturity.
Identification of Kentucky Bluegrass Cultivars with Esterase and Phosphoglucomutase Isoenzyme Markers1
Authors: Wu Lin , Harivandi Ali H. , Harding James A. , Davis William B.
Published: July 2010

Starch gel electrophoresis was used to further extend the identification of Kentucky bluegrass cultivars. A total of 24 cultivars were examined for isoenzyme variation in esterase (EST), phosphoglucomutase (PGM), phosphoglucoisomerase (PGI), and glutamate‐oxaloacetate transaminase (GOT) using starch gel‐electrophoresis. Esterase and phosphoglucomutase patterns were varible among the 24 cultivars. ‘Baron’, ‘Fylking’, ‘Merion’, and ‘Newport’ were examined for isoenzyme pattern differences between seed and seedling materials. Differences of esterase isoenzyme patterns were found between the two kinds of tissues. Seeds of ‘Adelphi’ and ‘Glade’ harvested from different fields and years were examined for isoenzyme consistency and within seed lot variation. Variation within seed lots differed from seed lot to seed lot. If seedlings from a seed lot were mixed, a constant pattern of both EST and PGM isoenzyme systems was obtained for different seed lots of the same cultivar. Therefore the process of mixing seedlings allows the finger‐printing characterization for Kentucky bluegrass cultivars even if there is occasional segregation from sexual reproduction.
Differential Nodulation Tolerance to Nitrate Among Legume Species
Authors: Harper J. E. , Gibson A. H.
Published: July 2010

Eight legume species were grown in hydroponic culture in controlled environment (CERES phytotron) facilities to determine if the species exhibited differential nodulation tolerance to nitrate nutrition (0, 1.0, and 4.0 mM initial concentrations, allowed to deplete with plant growth). Visible nodule appearance on roots of lupin (Lupinus angustifolius L.), pea (Pisum sativum L.), subterranean clover (Trifolium subterraneum L.), chickpea (Cicer arietinum L.), and siratro [Macropilium atropurpureum (DC:) Urb.] was less sensitive to nitrate than that roots of soybean [Glycine max (L.), Merr.], lablab bean [Lablab purpureus (L.) Sweet], and barrel medic (Medicago truncatula Gaertn.). The latter species also showed marked inhibition of nitrogenase (acetylene reduction) activity with 1.0 mM nitrate treatments, compared with respective 0 mM nitrate controls. The other five species showed similar or higher nitrogenase activity with the 1.0 mM nitrate treatment than with the respective controls. Nitrogenase activity with the 4 mM nitrate treatment was severely (>90%—lupin, chickpea, siratro, soybean, barrel medic, lablab bean), moderately (69%—pea) or slightly (27%—sub clover) inhibited, relative to respective controls. Rates of nitrate depletion from solution and levels of nitrate reductase activity in leaves and roots varied appreciably among species, however no clear relationship was evident that either rate of NO‐3 uptake or site of NO‐3 metabolism was responsible for the differential delays in nodule appearance. Of the species compared, nitrogenase activity of sub clover was least affected by the 4 mM nitrate treatment, and the amount of nitrate remaining in the nutrient solution at the end of the experimental period was greatest for this treatment combination. This indicated that efforts to overcome the inhibitory effect of nitrate on legume nodulation should possibly concentrate on limiting the uptake and/or metabolism of nitrate.
Comparative Growth of Obsolete and Modern Cotton Cultivars. II. Reproductive Dry Matter Partitioning1
Authors: Wells Randy , Meredith William R.
Published: July 2010

Although cotton (Gossypium hirsutum L.) lint yield increases have been realized as a result of plant breeding efforts, there is little documentation concerning alterations induced in reproductive growth patterns by selection processes. This study was designed to give insight into those facets of reproductive dry matter partitioning which have been altered via breeding programs based on the selection for yield. Twelve cultivars, six each from both the Stoneville and Deltapine backgrounds, were planted on either 26 Apr. or 12 May 1982. Reproductive growth was monitored at various times during the season by both numbers and dry weights of squares, immature bolls, and mature bolls. In addition, flowers were counted on a row of each plot every week during July and August. There were no significant planting date interactions regarding cultivar differences. The modern cultivars produced a greater proportion of their squares and flowers earlier than the obsolete cultivars. There were significant correlation coefficients for the relationship of cultivar release year to total flowers occurring before 90 days after planting (DAP) (r = 0.61 and 0.57 for the April and May plantings respectively). The trend of greater production of early squares and flowers results in larger amounts of early bolls in the newer cultivars. The percentage of total bolls lost due to abscission between 117 and 142 DAP is similar for most cultivars. Therefore, the greater number of bolls produced by the new cultivars at 142 DAP is attributable to the quantity present prior to shedding. The modern cultivars exhibited greater reproductive to vegetative ratios with ‘STV 213’, ‘STV 825’, ‘DPL 41’, and ‘DPL 16’ having 0.95, 0.86, 0.84, and 0.71 kg reproductive dry weight/kg vegetative dry weight at 117 DAP, respectively. The modern cultivars appear to produce a larger lint yield by two major processes. The first is a greater partitioning of dry matter to reproductive organs. The second is an increased amount of reproductive development occurring when maximal leaf mass and area are present.
Ear Height and Weight as Related to Stalk Lodging in Maize1
Authors: Helms T. C. , Compton W. A.
Published: July 2010

Measurements of ear height, ear weight, and a potential torque index were made on individual plants jointly chosen from within 972 hills of maize (Zea mays L.). A stalk lodged and unbroken plant in each hill were measured. Plants were classified as stalk lodged or unbroken plants whether or not they were root lodged. The measurements on each were then compared. A paired Student's t test was used to see if stalk lodged and unbroken plants differed for the traits measured. Potential torque was calculated by multiplying ear height by ear mass. No relationships were found between ear height, ear weight, or potential torque and stalk lodging. The results are encouraging to those using stalk lodging in selection indices.
Two New Alleles at the sm1 Locus in Cotton1
Authors: Lee Joshua A.
Published: July 2010

Two new alleles were sited at the sm1 locus of tetraploid Gossypium hirsutum L., upland cotton. One allele, derived from the wild Hawaiian tetraploid species, G.tomentosum Nutt. ex Seem., removed all trichomes from stems and most of the trichomes from mature leaves. The allele is dominant to “normally pubescent”, the phenotype of most cultivars of upland cotton. The second allele steins from the Peruvian diploid species, G. raimondii Ulbr. The allele greatly enhanced density of tomentum of the upland cultivar ‘Empire,’ is dominant to “normally pubescent,” and masks the expression of Sm2 (A subgenome glabrousness allele). The finding of an allele at the sm1 locus that enhances the density of pubescence, taken along with three other alleles at the locus that remove varying amounts of pubescence from the cotton plant, suggests that the sm1, locus of the D subgenome is the homoeologue of the sm2, or h1, locus of the A subgenome which bears an assortment of alleles that produce similar effects.
Partitioning of Symbiotically Fixed Nitrogen in Soybeans and Alfalfa1
Authors: Henson R. A. , Heichel G. H.
Published: July 2010

A growing body of evidence suggests a differential partitioning of soil N and symbolically fixed N2 among organs during ontogeny of some legumes. This partitioning is poorly understood for soybeans [Glycine max (L.) Merr.] and only meager evidence of this phenomenon is available for perennial forage legumes such as alfalfa (Medicago saliva L.). Therefore, we compared the partitioning of fixed N, among organs of soybean and alfalfa grown on a silt loam (Typic Hapludoll) by periodically sampling throughout one growing season. Dinitrogen fixation and partitioning of fixed N2 were measured with the 15N isotope dilution technique. Evidence of differential N partitioning was obtained for both species. The roots of alfalfa contained a higher proportion of fixed N2 throughout the growing season compared with the stems, leaves, and the whole plant. The roots, stems, and young seeds of soybeans contained a lower proportion of fixed N2 throughout the season compared with the whole plant. In comparison with the N composition of the whole plant, the N in pod walls contained a higher proportion of fixed N2 and that in green leaflets was unchanged. Senesced leaflets and petioles exhibited a reduced proportion of fixed N2 coincident with an increased proportion of fixed N2 in the whole plant. This suggests a preferential mobilization of fixed N2 compared with soil N. The results suggest a differential allocation of symbiotic N2 in alfalfa and soybean that is related to the availability of soil N and the composition of the mobile N reserves at specific developmental stages. The accumulation of symbiotic N2 in pod walls of soybean might reflect a limitation of N transport to young seeds, and deserves further investigation.
Linkage Analysis of the Male‐Fertility Restorer Gene, Rf, in Cotton1
Authors: Kohel R. J. , Quisenberry J. E. , Dilbeck R. E.
Published: July 2010

The gene Rfpartially restores male fertility to upland cottons, Gossypium hirsutum L., that have the cytoplasm of the wild diploid species G. harknessii Brandg. The Rf gene is linked with the deleterious Cracked root gene, Rc. The chromosomal location and additional linkage associations of Rf have not been identified. Knowledge of such associations could be useful in the transference and manipulation of the Rf/gene. In this study we tested 13 genetic marker loci distributed on at least nine chromosomes, for possible linkage with Rf. No such associations were detected.
Differences in Mycorrhizal Colonization of Maize Selections for High and Low Ear Leaf Phosphorus
Authors: Toth Ronald , Page Teresa , Castleberry Ron
Published: July 2010

Mycorrhizal colonization may contribute to the uptake of P in crop plants, particularly under nutrient limited conditions. This study was done to evaluate the hypothesis that inbreds of maize (Zea mays L.) previously selected for differences in ear leaf P at silking, may differ in degree of mycorrhizal colonization. Roots of up to six inbreds (three high P and three low P) were assayed for mycorrhizae after 10 weeks growth under field conditions. A positive rank correlation was observed between ear leaf P content of the inbreds and their percent mycorrhizal colonization. The high P inbreds were more mycorrhizal (18% mean colonization) than the low P inbreds (10% mean colonization). The same six maize inbreds were also grown in the greenhouse under nonmycorrhizal conditions in 1983. Neither tops or roots showed growth or P content characteristics under nonmycorrhizal conditions which would explain the differences observed in the field in ear leaf P content or mycorrhizal colonization. These data suggest mycorrhizal colonization may be a significant component of the genetic differences expressed as ear leaf P content in these maize lines.
Polar‐Glycerolipid Metabolism in Soybean Seed with Genetically Altered Unsaturated Fatty Acid Composition1
Authors: Carver Brett F. , Wilson Richard F.
Published: July 2010

Recurrent selection methodology has been utilized in the development of a soybean [Glycine max (L.) Merr.] genotype, designated as N78‐2245, that contains a high concentration of oleic acid (18:1) and lower concentrations of linoleic (18:2) and linolenic (18:3) acids compared to seed from typical soybean cultivars. Ontogenetic changes in total polar‐glycerolipid (TPL) composition were characterized for the first time in N78‐2245 and in ‘Dare’, a typical soybean cultivar. The objective of this work was to determine whether the overall rate of 18:l‐desaturation changed with increased seed for a given genotype and to assess the level of 18:l‐desaturase activity in genotypes that differed in 18:1 content. Phosphatidylcholine (PC) was found to be more active metabolically than any other polar‐glycerolipid. Genotypic differences in the concentration of PC species enriched in 18:1 were expressed throughout seed growth. At 45 days after flowering the 18:1‐PC concentration in the high‐18:l genotype, N78‐2245, was 4.2‐times greater than that in the standard cultivar, Dare. As these genotypes matured the concentration of 18:1‐PC declined, and the concentration of species enriched with linoleic acid (18:2) increased. The overall rate of 18:1‐PC desaturation activity did not change with increased seed age in either genotype. Hence developmental changes in 18:1‐PC species concentration were not the result of changes in acyldesaturase activity. A reduced rate of overall desaturation activity in N78‐2245 as compared with Dare, however, may have contributed to the higher levels of 18:1 in glycerolipids from N78‐2245 seed.
Comparison of F1's and Inbreds as Female Parents for Sorghum‐Sudangrass Seed Production1
Authors: Gorz H. J. , Toy J. J. , Haskins F. A. , Ross W. M.
Published: July 2010

Two field studies involving different groups of germplasm were conducted to compare sorghum‐sudangrass, Sorghum bicolor (L.) Moench ✕ S. sudanense (Piper) Stapf, hybrid seed production of male‐sterile F1's with their component A‐lines. The F1's yielded 45 and 82% more grain than their A‐line counterparts in Study 1 and 2, respectively, with the increase attributable to more seeds per panicle and a greater threshing percentage. Mean values of nine traits measured on nine groups of eight F1's in Study 1 and seven groups of six F1's in Study 2 were compared with their respective A‐lines. All groups of F1's significantly outyielded their A‐line counterparts in both studies except for A‐line N35 in Study 1. Phenotypic correlations of yield and seeds per panicle were high in both A‐lines and F1's in both studies, as were the correlations of yield and threshing percentagexcept for the F1's in Study 1. Application of these findings should facilitate the production of higher yields of sorghum‐sudangrass hybrid seed at reduced cost per unit of seed. The best F1's to use and the magnitude of their superiority over A‐lines will be influenced by the location in which seed is produced.
CO2‐Enrichment Effects on Soybean Physiology. II. Effects of Stage‐Specific CO2 Exposure1
Authors: Ackerson R. C. , Havelka U. D. , Boyle M. G.
Published: July 2010

Soybeans [Glycine max (L.) Merr ‘Wye’] were exposed to CO2‐enriched atmospheres during specific stages of development Carbon dioxide enrichment from early pod development until plant maturity and from emergence to maturity increased seed yield 27 and 36%, respectively, compared with plants exposed to the normal atmospheric level of CO2. Plants receiving supplemental CO2 from either emergence to anthesis or from anthesis through early pod development did not exhibit an increase in grain yield. During each period of exposure, CO2‐enriched plants had higher rates of photosynthesis and accumulated significantly more starch, sucrose, and glucose in the leaves compared with nonenriched controls. After exposure to CO2 was terminated, rates of photosynthesis declined to control values and the accumulated leaf carbohydrates were rapidly depleted. Accumulation and subsequent utilization of stored photosynthate did not appear to influence seed yield except when these stored reserves were available at the onset of the grain‐filling period. Seed yield increases attributable to CO2 enrichment were the result of more pods per plant rather than increases in seed size. From the analysis of photosynthetic data and the trends in carbon accumulation and utilization, it appears that soybeans could support a higher degree of reproductive growth.
Ear Resistance of Maize Inbreds to Field Aflatoxin Contamination1
Authors: Widstrom N. W. , Wilson D. M. , McMillian W. W.
Published: July 2010

A study was conducted to identify resistant genotypes for incorporation into a breeding population for recurrent selection. An eight‐line diallel of sweet corn (Zea mays L.) single crosses and a nine‐line diallel of dent single crosses were grown in replicated experiments for 3 years. Ears were knife inoculated at 20 days after full silk with an Aspergillus flavus Link (NRRL 3357) spore suspension, and grain was evaluated at maturity for total aflatoxin contamination. The Grilling Model I, Method 4, was used to partition genetic variation. General combining ability (GCA) was significant among inbreds in the dent and sweet corn diallels. No specific combining ability (SCA) effects were detected in either of the analyses combined over years, but an SCA ✕ years interaction occurred in the analysis of sweet corn crosses. The GCA and SCA effects were significant in two of three dent corn analyses within years. The 1981 analysis revealed significant GCA and SCA effects for the sweet corn diallel. Those analyses in years with very low aflatoxin contamination yielded nonsignificant GCA effects. Two or three inbreds within each set performed well enough as single crosses to be used as sources of resistance in breeding populations. Present methods of inoculation do not always produce enough contamination to identify resistant genotypes. Because of this and the cost of analyses, additional evaluations are often needed to efficiently identify desirable genotypes.
Environmental Physiology of Sorghum. II. Epicuticular Wax Load and Cuticular Transpiration1
Authors: Jordan W. R. , Shouse P. J. , Blum A. , Miller F. R. , Monk R. L.
Published: July 2010

The effect of epicuticular wax (EW) load on the cuticular transpiration rate (Tc of sorghum [Sorghum bicolor (L.) Moench] leaves was studied. Leaves from bloom, bloomless, and sparse bloom isogenic lines and various bloom‐type hybrids were collected from field plots after anthesis in 1976, 1977, and 1981. Epicuticular wax was extracted with chloroform and quantified using a colorimetric method. The Tc of detached leaves were measured with a humidity sensor in a closed cuvette or calculated from the mass of water lost per unit time under standardized conditions. The Tc increased as EW decreased over the range of 0.1 to 0.03 g m−2 when data from all genotypes were pooled for analysis. However, among the normal (bloom) phenotypes there was no clear association between rates of water loss and EW. These data suggest that EW greater than about 0.067 g m−2 provide an effective barrier to water loss through cuticles of sorghum leaves under most conditions. Although the two methods of measuring Tc produced the same qualitative results, Tc rates calculated from the mass of water transpired under more “realistic” controlled conditions were higher and probably more directly related to rates of water loss under field conditions. Because of its speed and technical simplicity, the water loss method appears superior when large numbers of samples must be evaluated.