bluuebunny/crossref_metadata_2025 huggingface dataset:
Seed Quality Influence on Plant Growth and Dinitrogen Fixation of Red Field Bean
Authors: Rodriguez A. , McDonald M. B.
Published: July 2010

Field bean (Phaseolus vulgaris L.) seeds represent an important nutritional component of the diets of many people in developing countries. Yet yields of this high‐protein crop are typically much less in developing compared with developed regions. Seed quality is difficult to maintain in developing countries and can influence the growth and yield of many crops. This study evaluated the seed quality effect on emergence, plant growth, yield, and N2 fixation of ‘Pompadour Checa’ field bean. Both naturally and artificially (1, 2, and 3 d at 41 °C and 100% RH) aged seeds were planted in 1984 and 1985 in a Crosby silty clay loam (fine, mixed, mesic Aerie Ochraqualf) with an organic matter content of 3 to 5%. Percent emergence and normal seedlings decreased while percent abnormal seedlings increased with increasing seed deterioration. Plant growth was evaluated at the V3, R6, and R8 growth stages. Decreasing seed quality generally culminated in less top and root growth and less seed yield. Decreased seed yield was attributed to fewer seeds produced per plant, since no significant decrease in seed weight was observed. Seeds of lower quality also produced plants with fewer nodules, less nodule weight, and less dinitrogen fixation as determined by the acetylene reduction assay. The observed differences in plant vegetative and reproductive growth from seeds differing in quality may be associated with their ability to successfully form root nodules and fix N.
Alfalfa Morphological Stage and its Relation to in Situ Digestibility of Detergent Fiber Fractions of Stems
Authors: Sanderson Matt A. , Hornstein J. S. , Wedin W. F.
Published: July 2010

A reliable index for quantifying maturity and predicting herbage quality of alfalfa (Medicago sativa L.) grown in diverse environments would be useful. An index developed at Cornell University was used to compare the in situ rate and extent of digestibility of neutral‐detergent fiber (NDF), cellulose, and hemicellulose of spring‐ and summer‐grown alfalfa stems at similar morphological stages. Stems were harvested every 10 d during spring growth and summer regrowth of 1984 and 1985. Maturity at each harvest was classified on a scale of 0 to 9, and a mean stage number was calculated. Ground (2 mm) stems were ruminally incubated in dacron bags for 0 and 48 h in 1984 and 0, 3, 6, 9, 12, 24, 48, and 72 h in 1985. Residues were extracted sequentially with neutral and acid detergent to determine residual NDF, cellulose, and hemicellulose. Rate of digestion (1985 data only) was calculated via nonlinear regression. After 48 h in the rumen, NDF, cellulose, and hemicellulose of spring‐grown stems were digested to a greater extent than summer‐grown stems of comparable chronological age. Digestibility of NDF [R2 = 0.78, root error mean square (REMS) = 64 g kg−1, cellulose (R2 = 0.78 REMS = 58 g kg−1), and hemicellulose (R2 = 0.83, REMS = 59 g kg−1) declined nonlinearly with increasing maturity stage. Digestion rate of NDF, cellulose, and hemicellulose was faster in vegetative stems (average = 0.164 h−1) compared with reproductive stems (average = 0.093 h−1). Hemicellulose was digested 80% faster than cellulose. Our data demonstrated a close association between in situ digestibility of detergent‐fiber fractions and the Cornell index and further supports its utility.
Relationships between Groat Percentage and Productivity in an Oat Head‐Row Series
Authors: Bunch R. A. , Forsberg R. A.
Published: July 2010

Selection for high groat percentage, an important quality factor in oat (Avena sativa L.), is practiced in nearly all oat improvement programs. In the Wisconsin oat breeding program, it has been noted that vigorous, productive‐looking breeding lines often have kernels with below‐average groat percentage. The purpose of this study was to determine the relationships of groat percentage with plant growth, measured as vegetative weight, and grain production of primary culms for early generation oat lines (F3 to F6) in a head‐row selection scheme. In a parent/progeny study, groat percentage of panicles evaluated in 1982 was negatively correlated with grain weight, panicle weight, vegetative weight, and biomass measured on their progeny lines grown in 1983 and on families in 1984. Similar negative correlations were found between groat percentage measured in 1983 and productivity traits measured on progeny in 1984. In a pure line study with 15 genotypes, correlations were similar to those obtained in the parent/progeny study. This negative relationship suggests that selection for high groat percentage in early generations may result in decreased vegetative and seed productivity.
Barley Yellow Dwarf Symptom Severity in Oat Affected by Plant Growth Stage at Infection and Plot Type
Authors: Goulart L. R. , Ohm H. W. , Foster J. E.
Published: July 2010

Lack of a standard method for evaluation of barley yellow dwarf (BYD) symptoms may result in inconsistency for genetic evaluation. The BYD symptoms were determined in oat, Avena sativa L., subsequent to virus infection at three plant growth stages and with two types of field plots. Five treatments: noninoculated; and inoculated at the two‐ to three‐leaf (transplanted), three‐leaf, four‐ to five‐leaf, and stem elongation stages (direct seeded) were whole plots. Five oat cultivars were subplots. Two types of plots, hill and space planted, were whole units across the five cultivars. Seven traits were measured: BYD symptoms, plant height, heading date, grain yield and yield components. The plot types were not significantly different and there was a high correlation between the types of plot for these characters. Cultivar rank was similar at all growth stages, indicating that sensitive cultivars may be severely damaged by BYDV infection at any stage of development. Small differences among cultivars for tolerance to BYDV were detected, subsequent to infection at the stem elongation stage under conditions of moderate temperatures and well distributed rainfall during the growing season. The plants that were transplanted after inoculation at the two‐ to three‐leaf stage were more severely affected by BYDV than plants that were seeded in the field and inoculated at the three‐leaf stage. Differences among cultivars were most distinct for BYD symptom, kernel weight, grain yield, number of kernels per panicle and plant height. Inoculation at the three‐leaf stage resulted in maximum differences among cultivars and hill plots involved minimal effort for BYDV evaluation.
Corn Seed Vigor Effect on No‐Tillage Field Performance. I. Field Emergence
Authors: TeKrony D. M. , Egli D. B. , Wickham D. A.
Published: July 2010

Delayed seed germination and slow seedling growth commonly occur following no‐till planting of corn (Zea mays L.) seed. This investigation was conducted to evaluate the effect of seed vigor on seedling emergence under a wide range of no‐tillage soil environments. Four seed lots of B73 ✕ Mol7, which had good germination (88‐98%) but a range in seed vigor, were no‐till planted into soft red winter wheat (Triticum aestivum L.), tall fescue (Festuca arundinacea L.) sod, and corn residue at three planting dates in 1982 to 1984. Stress (low soil temperature and high soil moisture) occurred at the early planting date (mid‐April) in 2 of 3 yr, while near‐ideal soil conditions occurred at the other planting dates. Maximum soil temperatures at the early planting date following no‐tillage into wheat stubble and corn stalks were similar to conventional tillage, but much greater than no‐tillage into tall fescue sod. The low‐ and medium‐vigor seed lots had consistently lower emergence than high‐vigor seed lots in all tillage systems and planting dates. Emergence following conventional tillage was consistently greater than emergence following all no‐tillage treatments; however, this difference was significant only at the early planting date in 1982 and 1983. Under the stress conditions that occurred in the early planting date in 1982 and 1983 following no‐tillage, the high‐vigor seed lots had significantly greater emergence than low‐vigor seed lots. Thus, selecting seed lots with high germination and vigor would be beneficial for early plantings in no‐tillage systems.
Corn Seed Vigor Effect on No‐Tillage Field Performance. II. Plant Growth and Grain Yield
Authors: TeKrony D. M. , Egli D. B. , Wickham D. A.
Published: July 2010

No‐till planting of corn (Zea mays L.) seed may result in delayed germination and slower seedling growth. The objective of this research was to evaluate the effect of seed vigor on plant growth and yield of corn planted in various surface residues without tillage. Four seed lots of B73 ✕ Mol7, which had good germination (88‐98%) but a range in seed vigor, were no‐till planted into soft red winter wheat (Triticum aestivum L.), tall fescue (Festuca arundinacea L.) sod, and corn residue at early, midseason, and late planting dates in 1982 and 1984. Vegetative plant weight, plant height, and leaf area were measured at the four‐collar leaf stage and at 50% silking. Grain yield was measured at maturity. The weight, leaf area, and height of plants from the low‐vigor seed lots were consistently less than plants from the high‐vigor seed lots in all treatments at the four‐collar stage. Similar trends were seen at silking; however, the differences were much smaller and usually not significant. In most cases, seed vigor had no effect on grain yield. The few treatment combinations with reduced yields for the low‐vigor seed lots also had reduced seedling emergence. Thus, there was no direct effect of seed vigor on yield; however, the effect of seed vigor on seedling emergence can affect yield if less‐than‐optimum plant populations are obtained.
Partial Dominance of Susceptibility in Soybean to Soybean Cyst Nematode Races 3, 4, and 5
Authors: Rao‐Arelli A. P. , Anand S. C. , Myers G. O.
Published: July 2010

Five soybean [Glycine max (L.) Merr] genotypes, each with an unrelated source of cytoplasm, were crossed to produce eight F1 hybrids including reciprocals. These were evaluated for reaction to three races of soybean cyst nematode (SCN), Heterodera glycines Ichinohe in a greenhouse. Our objectives were to: (i) evaluate soybean F1 hybrids for partial dominance of susceptibility over resistance in susceptible parents and (ii) determine the role of cytoplasm for reaction to the selected populations of SCN Races 3, 4, and 5. Single seedlings were inoculated with approximately 1000 eggs and larvae of either of the three races of SCN. Plant roots were washed after 30 d and white females counted. Occurrence of significantly (P ≤0.05) fewer number of white females on reciprocal F1s compared to the susceptible parents in six of the eight crosses studied indicated partial dominance of susceptibility. Soybean PI 88788 nuclear genes for resistance to SCN Race 4 appeared to express a significantly (P ≤0.05) different reaction in two crosses with two different susceptible parents. No significant (P ≤ 0.05) differences were observed between reciprocal crosses for SCN reaction, indicating lack of maternal/ cytoplasmic influences in the parents. These results provide additional useful information on genetics of resistance to SCN reaction.
Diversity Among Pearl Millet Landraces Collected in Central Burkina Faso
Authors: Wilson J. P. , Burton G. W. , Zongo J. D. , Dicko I. O.
Published: July 2010

Evaluation of genetic diversity within germplasm collections is important to plant breeders who desire sources of genes for particular traits. The S1 bulks of 103 landraces of pearl millet [Pennisetum glaucum (L) R. Br.] collected in central Burkina Faso, West Africa were evaluated for morphologic characteristics in an attempt to differentiate among the landraces. Seed shape, seed color, and 100 seed weight were evaluated. Maturity and height of field‐grown plants were assessed in 1987 and 1988, and panicle length and diameter were measured in 1988. Frequencies of chlorophyll‐deficient seedlings were determined. These descriptors, in addition to previously reported data of their resistance to Pyricularia grisea (Cke.) Sacc., Puccinia substriata Ell. & Barth vat. indica Rach. & Cumin., and Moesziomyces penicillariae (Bref.) Vanky, and seed set after inoculation with M. penicillariae were analyzed by Ward's cluster analysis. The landraces could be grouped into ten dusters of phenotypic diversity. There was some correspondence between the geographic collection sites of landraces and their inclusion in particular clusters. Analysis of morphologic and disease resistance descriptors was useful for identifying likely duplicates within the collection, and will facilitate identification of potentially different sources of desired traits.
Genetic Effects on the Timing of Ledav2 Induced Necrosis of Cotton
Authors: Rooney William L. , Stelly David M.
Published: July 2010

Cotton (Gossypium spp.) embryos carrying the Ledav2 allele in combination with the Le1 allele at the Le1 locus and/or the Le2 allele at the Le2 locus undergo a hybrid lethality reaction, which causes progressive necrosis and death between germination up to 21 d postgermination. Timing of the necrosis is thought to be controlled by the cumulative dosage of alleles Le1 and Le2 interacting with Ledav2, but there have been no studies to identify the exact genetic relationship between the alleles Le1, Le2, and Ledav2 in terms of timing of necrosis induced by the Ledav2 complementary lethality system. The objectives of this study were to determine: (i) if the timing of necrosis is under genetic control of the loci Lel and Le2, and (ii) if the mechanism of timing or mode of gene action is consistent across genotypes. Five cultivars (Le1Le1Le2Le2) were used as sources of Le1 and Le2 alleles. Seedlings from reciprocal crosses of (cultivar ✕ le1le1le2le2) F1 plants and an le1le1Ledav2Ledav2 tester were scored for the presence and timing of the lethal reaction. Frequency histograms were used to phenotypicaily group seedlings according to the time of death. Observed frequencies of the phenotypic groups were tested against frequencies expected for digenic segregation. Results indicated that increased dosage of alleles Le1 and Le2 with Ledav2 hastens necrosis, but variation among cultivars indicated that Le1‐Ledav2 and Le2‐Ledav2 interactions may not always be distinctly different. Three possible explanations for these differences are: (i) that additional loci are involved, (ii) that allelic action is modified by background genotypic differences, and/or (iii) that the Le1 and Le2 loci are polymorphic.
Apomixis and Sexuality in Eastern Gamagrass
Authors: Burson B. L. , Voigt P. W. , Sherman R. A. , Dewald C. L.
Published: July 2010

Apomixis has been reported in eastern gamagrass [Tripsacum dactyloides (L.) L.I, but considerable uncertainty exists concerning the mechanism of apomixis involved. Because of this and the recent interest in improving the grass by breeding, this study was undertaken to characterize apomixis in eastern gamagrass. Megasporogenesis and embryo sac development were observed in ovules of eight eastern gamagrass genotypes: five diploid pistillate plants (2n = 2x = 36), two triploid (2n = 3x = 54) accessions, and one tetraploid (2n = 4x = 72) accession. The triploid and tetraploid accessions were apomictic. In these three, the megaspore mother cell enlarged; but rather than undergoing meiosis, the cell remained meiotically inactive. The only apparent changes were continued cell elongation and vacuolation. Eventually, the nucleus of the elongated megaspore mother cell divided mitotically and subsequently produced an 8‐nucleate embryo sac, which appeared similar to a Polygonum type sac. The embryo developed parthenogenetically. Pollination or fertilization was necessary for endosperm development, which indicates pseudogamy. The diploid plants reproduced by normal sexual means. After the first mitotic division, there was no difference in the appearance between the apomictic and sexual embryo sacs. These findings confirm that the apomictic mechanism in eastern gamagrass is diplospory of the Antennaria type followed by pseudogamy.
Prediction of Botanical Composition Using NIRS Calibrations Developed from Botanically Pure Samples
Authors: Coleman S. W. , Christiansen S. , Shenk J. S.
Published: July 2010

Point quadrat, hand separation, and histological methods for determining botanical composition are tedious, time consuming, and expensive. Near‐infrared reflectance spectroscopy (NIRS) was used as a rapid method to predict botanical composition of grass‐legume mixtures clipped from field plots. Our objective was to determine if a group of samples, each consisting of one of three botanical components, could be used for calibration in lieu of samples containing mixtures of the components. Calibration equations were developed for NIRS prediction of a number of legumes, Caucasian bluestem [(Bothriochloa caucasica (Trin.) C.E. Hubb.], and cheatgrass (Bromus tectorum L.). Hand separations of clipped mixtures were used to validate the calibration equations. All forage samples were grown in silty soils of the Dale series. Some evidence existed for an interaction between light scatter and mixing of two pure species, but it was eliminated effectively by second derivative transformation of the spectra. Biases existed for all components (36‐61 g/kg) but were smaller than standard errors of performance (52‐104 g/kg), except for legumes. Linearity was excellent for prediction for percentage legume, and validation was more precise for legume than for Caucasian bluestem or cheatgrass. This method of calibration for a closed population is recommended. Care must be taken to validate equations using mixed samples to insure linearity of unknowns between the extremes. Further, unknowns should be scanned along with calibration samples so that the same day to day instrument variation is associated with both sample sets.
Field Evaluation of Soybean for Mexican Bean Beetle Resistance. II. Maturity Groups III, IV, and V
Authors: Kraemer M. E. , Rangappa M. , Mebrahtu T. , Benepal P. S.
Published: July 2010

Field screening of soybean, Glycine max (L.) Merr., germplasm for resistance to insect defoliation was undertaken because of the narrow genetic base currently available to plant breeders and the lack of a comprehensive screening for resistance in most maturity groups (MGs). This study was conducted to evaluate plant introductions (PIs) in MGs III, IV, and V for resistance to defoliation by Mexican bean beetle (MBB), Epilachna varivestis Mulsant. All available Pis were screened to 475822C, 476914, and 424553 in MGs III, IV, and V, respectively, at the Randolph Research Farm of Virginia State University, Petersburg, VA. Resistance was determined by visually estimating the percent defoliation by MBB. Soybean accessions were initially screened in 2‐m rows. Selections from these screenings were twice retested in triplicate. Maturity Group V contained most of the resistant germplasm, including PIs 423901‐1, 417235 (‘Ouu 3’), and 200450 (‘Akita Ahi’). However, two breeding lines (L76‐0132 and L76‐0049), derived from the highly resistant PI 171451 in MG VII, had the least defoliation in MG V. Three moderately resistant PIs (360847 [‘Shiromeyntaka’], 248511 [‘Hakuho No. 1’], and 407820) were found in MG IV. PI 417152 (‘Mikuri 42’) (MG III) also showed some resistance. Higher levels of insect resistance appear to be present in later maturity group soybean germplasm.
Wheat Curl Mite and Wheat Streak Mosaic in Moderate Trichome Density Wheat Cultivars
Authors: Harvey T. L. , Martin T. J. , Seifers D. L.
Published: July 2010

The landing efficiency of the wheat curl mite (WCM), Eriophyes tulipae, is increased on wheat (Triticum aestiwm L.) cultivars that have high densities of leaf trichomes. This results in a higher incidence of wheat streak mosaic (WSM), which is caused by wheat streak mosaic virus (WSMV) and vectored by the WCM. This study was conducted to determine if moderate levels of leaf trichomes, found on many commonly grown cultivars, can have a significant effect on a cultivar's susceptibility to WSMV. Cultivar trichome density was assessed on greenhouse‐grown plants. The relative ability of WCM to land on the cultivars was tested in the greenhouse by exposing the plants to airborne WCM and making WCM counts before reproduction occurred. The incidence of WSM in the field was assessed by the presence or absence of visual symptoms and numbers of WCM in spikes were measured during the 1987 and 1988 crop years, at Hays, KS. ‘Arkan’ and ‘TAM 108’ had moderate trichome densities on leaves two, four, and six (three‐leaf mean 28.4 and 22.8 mm−2, respectively) and were more heavily infested by WCM in greenhouse and field tests when compared to cultivurs (Century, TAM 107, Lurned, and Newton) that have low trichome densities (6.0, 8.6, 5.0 and 5.7 trichomes mm−2, respectively). The cultivurs with moderate levels of leaf trichomes also had more plants with WSM in both years. Cultivars (Century and TAM 107) with the rye (Secale cereale L)‐derived WCM resistance and few trichomes had the lowest incidence of WSM. Some cultivars now widely grown in Kansas may have sufficient pubescence to significantly increase their susceptibility to WSMV. New cultivars developed for areas where WSMV is a production constraint would probably benefit from having leaves with low trichome density.
Greenhouse Evaluation of Tall Fescue Genotypes for Rhizome Production
Authors: De Battista J. P. , Bouton J. H.
Published: July 2010

Increasing rhizome production in tall fescue (Festuca arundinacea Schreb.) is a desirable breeding goal because rhizomes promote persistence under conditions of stress. Evaluating rhizome production in the field is time‐consuming and difficult. This study was conducted to assess the possibility of using greenhouse evaluation to select endophyte‐free tall fescue genotypes for rhizome production. The effects of pot size and plant age on rhizome expression of tall fescue seedlings were studied. Means and ranks of 73 genotypes evaluated in the greenhouse and field were compared. Numbers of rhizomes and tillers were affected by pot size ✕ plant age interaction. Significant (P < 0.01) genotypes ✕ location (greenhouse or field) interaction and low, nonsignificant (P > 0.05) rank correlation coefficients among genotypes were obtained. At least 7 mo of growth were required before rhizome expression occurred in tall fescue seedlings under greenhouse conditions. Greenhouse evaluation might be useful for screening tall fescue genotypes for tiller production, but under the conditions of this study it does not appear to be useful in screening for rhizome production.
Leaf Orientation of Soybean Seedlings: II. Receptor Sites and Light Stimuli
Authors: Donahue Raymon , Berg Virginia Seymour
Published: July 2010

Unifoliolate leaves of seedlings of soybean [Glycine max (L.) Merr. cv. Northrup King S1346] exhibit diaheliotropic movements when well watered and paraheliotropic movements when water stressed. The movements originate at the pulvinus at the base of each leaf lamina. The receptor site for the light stimulus was located by covering portions of the leaf surface with India ink and observing the effect on leaf movement; the leaf lamina, leaf veins, and pulvinus were tested. The pulvinus was the receptor site for light that stimulates both diaheliotropic and paraheliotropic leaf movement. The role of different wavelengths of light in diaheliotropism and paraheliotropism was determined using filters that remove broad bands of light wavelengths. Blue light was necessary for both diaheliotropism and paraheliotropism. Interference filters were used to expose soybean leaves to selected blue‐light wavelengths. The amount of diaheliotropic leaf movement at each wavelength was used to obtain an action spectrum. There was one peak between 410 nd 440 nm and one between 470 and 490 nm. A nonphytochrome photoreceptor located in the pulvinus used blue light, in conjunction with other factors, to determine leaf orientation and thereby regulate light interception of leaves of soybean seedlings.
Phosphorus Nutrition Influence on Plant Growth and Nonstructural Carbohydrate Accumulation in Tobacco
Authors: Crafts‐Brandner S. J. , Salvucci M. E. , Sims J. L. , Sutton T. G.
Published: July 2010

Low phosphorus nutrition generally results in increased leaf starch accumulation. The objective of this study was to determine how P nutrition, ranging from deficient to supra‐optimum, affected plant growth and development and accumulation of nonstructural carbohydrates within the plant canopy. Tobacco (Nicotiana tabacum L. cv. KY 14 and Speight G28 and N. rustica L. cv. Pumila) plants were grown in the greenhouse in pots of soil that contained six (Exp. 1) or seven (Exp. 2) levels of P (P1‐P7, ranging from 0–2150 ha‐1). Plant growth increased with P level up to P4 (269 kg P ha‐1), whereas leaf P levels remained essentially constant up to P3 (134 kg P ha‐1) or P4. Above P4, growth was constant but leaf P levels continued to increase. Increased leaf P at high fertility rates did not influence nonstructural carbohydrate accumulation. Photosynthetic capacity was depressed below P4, but the decrease was not as great as the decrease in growth. Leaf sucrose levels were unaffected by P fertility. Starch levels were differentially affected by P fertility depending on the cultivar. For both G28 and Pumilla, low P fertility led to decreased starch accumulation. For KY 14, low P fertility led to increased starch accumulation. The activity of adenosine diphosphate glucose (ADPG) pyrophosphorylase was not correlated with starch accumulation. For all genotypes, total sugar accumulation increased between P1 and P4. The results indicated that low P nutrition did not consistently lead to increased starch accumulation in tobacco; rather, the effect depended on the cultivar and/or species.
Genotypes and Plant Densities for Narrow‐Row Cotton Systems. II. Leaf Area and Dry‐Matter Partitioning
Authors: Kerby T. A. , Cassman K. G. , Keeley M.
Published: July 2010

Interest in production of narrow‐row cotton (Gossypium hirsutum L.) is increasing. Plant characteristics considered important for cultivars grown in 1‐m row spacings may not be the same for plants grown in 0.76‐m spacings. This field study was conducted to determine the influence of genotype and plant density on accumulation and allocation of dry matter in a narrow‐row production system. Five genotypes representing a wide range in size and growth habit were grown in factorial tests at 5,10, and 15 plants m‐2 at the U.S. Cotton Research Station in Shatter, CA, in 1984 and 1985. Growth measurements were made four times during each season. Increasing plant density increased mean leaf area index (LAI) and total dry matter of genotypes at all sample dates but decreased harvest index (HI) from 0.58 to 0.53 at maturity. Genotypic differences in LAI and total above‐ground dry matter became apparent only after anthesis. Mean season‐end dry matter ranged from 9.78 Mg ha‐1 for the short determinate genotype 2086 to 10.88 Mg ha‐1 for ‘Acala SJ‐2’. Final mean HI ranged from 0.66 for 2086 to 0.47 for Acala SJ‐2. Height and vegetative growth rates (HGR and VGR) per 100 heat units (HU) were closely negatively associated with fruit growth rates (FGR) between the June and August sample dates. Including leaf area growth rate (LAGR) with FGR as a FGR/LAGR ratio as the independent variable improved r2 from 0.59 to 0.81 for HGR and from 0.69 to 0.90 for VGR. Node growth rate (NCR) was only minimally sensitive to the FGR/LAGR ratio. These results show that vegetative development during early fruiting is related to size and earliness of the reproductive sink and growth rate of the source. Cultural practices that are presently used for cultivars with a low FGR/LAGR ratio may not be ideally suited for more determinate cultivars with a high ratio.
Salinity Stress and Varietal Resistance in Rice: Effects on Whitebacked Planthopper
Authors: Salim M. , Saxena R. C. , Akbar M.
Published: July 2010

Plants grown under physicochemical stresses frequently become more susceptible to insects. We determined the effects of salinity stress at 1.0 and 1.2 S/m electrical conductivity on the magnitude and expression of resistance of rice (Oryza sativa L.) cultivars to Sogatella furcifera (Horváth) under glasshouse conditions using natural daylight of 12 h, 29/21 °C (day/night), and minimum 70% relative humidity. Salinity stress increased N, decreased K, and decreased the quantity of allelochemicals extracted as steam distillates from rice plants. Intake and assimilation of food, growth, adult longevity, fecundity, and population increase of the insect were significantly greater on plants grown at salinity level of 1.2 S/m than on unstressed control plants. Regardless of the level of stress, the difference between susceptibility of ‘Taichung Native 1’ (TN1) and resistance of ‘IR2035‐117‐3’ (IR2035) cultivars remained distinct. Painting of steam‐distillate extract of resistant IR2035 plants on susceptible TN1 plants made them less attractive and decreased food intake and assimilation by S. furcifera. In contrast, intake and assimilation of food increased significantly on IR2035 plants painted with TN1 extract. Effects of Physicochemical stresses, such as salinity, must be considered when breeding insect‐resistant rice cultivars for salinity‐prone areas.
Growth and Partitioning Characteristics of Four Peanut Genotypes Differing in Resistance to Late Leafspot
Authors: Pixley K. V. , Boote K. J. , Shokes F. M. , Gorbet D. W.
Published: July 2010

Genetic resistance in peanut (Arachis Hypogaea L.) to foliar diseases caused by Cercospora arachidicola Hori (CA) and Cercosporidium personatum (Berk. & Curt.) Deighton (CP) has usually been associated with low yields and late maturity. Some recently developed genotypes have partial resistance to CP and good yield potential. This study was conducted to understand growth and partitioning characteristics that contribute to yield potential of three leafspotresistant genotypes relative to the widely grown but susceptible cultivar Florunner. Crop growth, vegetative growth, reproductive growth, and partitioning intensity of Florunner, ‘Southern Runner’, F81206, and MA72x94‐12 were measured in field studies during two seasons in the presence or absence of fungicidal control of leafspots. In fungicide‐treated plots, the genotypes had similar crop growth rates, but differed in assimilate partitioning to pod growth (92, 80, 77, and 53% for Florunner, Southern Runner, F81206, and MA72x94‐12, respectively). In treated plots, high partitioning of assimilate to pods and early onset of pod fill enabled Florunner to achieve high yield in 127 d. In untreated plots, this high intensity of partitioning to pods limited Florunner's leaf production during pod fill and precluded replacement of diseased leaves. By contrast, Southern Runner, F81206, and MA72x94‐12 compensated partially for leafspot‐induced defoliation; later onset of pod fill (6 to 16 d) and lower partitioning to pods allowed greater leaf area growth during pod fill. A combination of leafspot resistance, lower partitioning to pods (allowing leaf growth), and slightly longer pod fill resulted in satisfactory yields from Southern Runner and F81206 without fungicidal control of leafspot.
Pollen Fertility of Some Simple and Compound Translocations of Cotton
Authors: Stelly David M. , Kautz Kenneth C. , Rooney William L.
Published: July 2010

Pollen semisterility can serve as a useful criterion for detecting cytogenetic deficiencies and heterozygosity of cytogenetic aberrations in many diploid crops. A modified form of the fluorescein diacetate‐based fluorochrome reaction method was recently developed and found to allow reliable detection of cytogenetically induced pollen semisterility of cotton (Gossypium hirsutum L., 2n = 4x = 52) simple reciprocal translocation heterozygotes. We report the pollen fertility levels of plants either homozygous (TT) or heterozygous (NT) for 20 translocations, including 16 two‐chromosome, three three‐chromosome, and one four‐chromosome translocations. Fertility ranged from 90 to nearly 100% for TT and from 52 to 81% for NT plants, indicating that TT and NT cytogenetic types in testcross populations that are segregating for a single translocation should be distinguishable on the basis of pollen fertility. Thus, all 45 breakpoints of the screened translocations are of potential use as genetic markers. These and previously published results demonstrate collectively that all identified translocations of G. hirsutum are amenable to pollen analysis by fluorescence microscopy, even though the species is a disomic tetraploid.
Lignin Concentration and Composition of Divergent Smooth Bromegrass Genotypes
Authors: Jung H. G. , Casler M. D.
Published: July 2010

Esterified phenolics of noncore lignin and core lignin concentration and composition are correlated with forage digestibility. In this study, divergent smooth bromegrass (Bromus inermis Leyss.) genotypes selected for high or low in vitro dry matter disappearance (IVDMD) were evaluated for genotypic variation of lignin concentration and composition. Primary growth of nine genotypes from each IVDMD selection group was harvested during 2 yrs and separated in to leaf blade and stem plus sheath fractions. Detergent fiber components, core lignin concentration and composition, and esterifled noncore lignin content were determined. Differences were observed between the IVDMD genotype groups for neutral detergent fiber (NDF), hemicellulose and cellulose concentration in leaf blade tissue, and NDF and hemicellulose concentration of stems. Core lignin concentration was greater in stem of the low IVDMD group but not leaves. Yield of core lignin products was greater for the low IVDMD group leaf blades but not stem plus sheath tissue. Genotypic variation existed between and/or within IVDMD genotype groups for molar proportions of vanillin, syringaldehyde, p‐coumaric acid, and ferulic acid from core lignin nitrobenzene oxidation products. Esterified ferulic acid concentration of noncore lignin was consistently greater in the high IVDMD group, but esterified p‐coumaric acid was only greater in stem tissue of the low IVDMD group. Differences observed between the IVDMD groups were generally consistent with previous reports of correlations between lignin fractions and IVDMD. Differential phenotypic correlation coefficients between lignin concentration and composition for the high and low IVDMD groups suggested some value to attempting divergent, independent selection for lignin concentration and composition. Resultant genetic materials would be valuable tools for addressing mechanistic questions about the role of specific lignin fractions as inhibitors of fiber fermentability.
Soybean Flower Abortion: Genetics and Impact of Selection on Seed Yield
Authors: Sharma Krishna P. , Dybing C. Dean , Lay C.
Published: July 2010

Although soybean [Glycine max (L.) Merr.] plants shed many flowers prior to pod development, the effect of this loss on realized seed yield has not been measured. Objectives of this work were to: (i) measure genotypic variation in raceme flower abortion (FA) and related traits, (ii) determine heritability of these traits, and (iii) study the impact of selection for differing levels of FA on seed yield. Field studies were conducted from 1982 through 1986 with 10 soybean genotypes differing in raceme length, number of flowers per raceme (FPR), and level of raceme FA, and with progeny from 13 crosses among them. The FA ranged from a low of 27% for ‘Amsoy’ to a high of 78% for ‘Chusei.’ Yearly variation in FA was detected only for two genotypes, but four genotypes showed annual variation in flowers raceme−1. Exceptions to the normal association of high FA with high number of flowers raceme−1 and distal flower positions on the raceme were observed in these genotypes and their progeny. Mean heritability estimate measured in F2 for 13 crosses was 47% for FA compared to 64% for FPR. Two populations were developed from the cross IX93‐100 ✕ Amsoy by selecting families on the basis of level of FA for all flowers on two racemes per plant in the F3 generation. When seed yield of the F3 derived lines in the F6 generation was measured, the yield of the higher yielding parent (Amsoy) was exceeded by 66% of the families selected for low FA. Of the population selected for high FA, 35% exceeded the yield of Amsoy and 17% yielded significantly less. Plant growth traits like maturation date, pod type, weight seed−1, and FPR were also altered by this procedure. Selection on the basis of the fate of flowers higher than the fourth position on the raceme in long raceme segregates is suggested as a procedural improvement for future research.
Selecting for Rapid Leaf Expansion in Early‐Maturing Maize
Authors: Cross H. Z.
Published: July 2010

Assimilate supply (source) reportedly limits grain yields (sink) of early‐maturing maize (Zea mays L.) hybrids. This field research sought to determine if selecting for high average leaf expansion rates (ALER) in early maize could increase leaf area without delaying maturity. Combining abilities of S2 (second selfed generation) lines with differing ALER values were estimated for ALER, leaf area/plant, silking date, leaf number, length and width, and ear and cob dimensions. The S2 hybrids were selected to represent a 2 ✕ 2 factorial arrangement of ALER types (HER = high ALER and LER = low ALER). Two groups (GI and GII) of lines were selected from S2 lines previously rated using the formula ALER = (leaf number ✕ ear leaf length ✕ ear leaf width ✕ 0.75)/(d to pollination). Four sets of lines with differing ALER ratings were paired by source population, year evaluated, and silking date. Within each set, the four S2 lines from GI were crossed to the four S2 lines from Gil to produce 16 hybrids representing a 2 × 2 factorial arrangement of four hybrids each of HER ✕ HER, HER ✕ LER, LER ✕ HER, and LER ✕ LER classes. Field experiments arranged in simple lattice designs were grown with two replicates for each of seven environments. Averaged across environments, hybrids from HER parents in both GI and GII had significantly higher ALER, due to more leaf area/plant. The HER hybrids had more, longer, and wider leaves than LER hybrids but silked earlier. Both general (GCA) and specific (SCA) combining abilities were detected, but there was little evidence of interaction with environments for GCA or SCA for ALER and its components. Data indicated that selection for high ALER in a single environment should enable breeders of early maize to increase leaf area (source) without delaying maturity.
Isolation and Analysis of Genomic DNA from Single Seeds
Authors: Kamalay Joe C. , Tejwani Raman , Rufener G. Keith
Published: July 2010

Our objective was to adapt a plant DNA minipreparation procedure for the rapid isolation of total nucleic acid from single legume seeds. Single‐seed extractions from cultivars of soybean (Glycine max L. Merr.) and frenchbean (Phaseolus vulgaris L.) were characterized for total nucleic acid yield, DNA content, and restriction fragment length polymorphisms (RFLPs). This procedure can employed in the analysis of a large number of individual seeds by genomic blotting and molecular hybridization. while probing seed lots with the same complementary DNA (cDNA) fragment, we found that ostensibly pure soybean seed lines contained significant levels of identical RFLPs while frenchbean seed lines from plants with dramatic morphological differences had no detectable RFLPs for the same sequence. When isolated genomic DNAs were used to detect restriction fragment length polymorphisms (RFLPs), it was possible to make limited distinctions among cultivars of both soybean and frenchbean seed lots. This technique met the criteria of simplicity, rapidity, and low cost, and yielded DNA fragments of sufficient purity and length for RFLP analysis.
Photosynthetic Carbon Dioxide Exchange, Leaf Area, and Growth of Field‐Grown Pea Genotypes
Authors: Mahon John D.
Published: July 2010

Genotypic variability in photosynthesis per unit of leaf area may be useful in increasing gross productivity of crop plants, but only if it can be demonstrated to be measurable and related to growth in field stands and if it is not physiologically linked to compensating differences in leaf area production. To examine these issues, six genotypes of pea (Pisum sativum L.), selected for differences in photosynthetic CO2 exchange per unit of leaf area (CER), were planted in replicate field plots at densities of 25 and 100 seeds m−2. Mean CER, leaf area index (LAI), and relative growth rate (RGR) were determined for each genotype ✕ density combination over six weeks of growth in two years. At the higher planting density, LAI increased by 72%, but CER and RGR decreased by 22 and 24%, respectively. Genotypes differed in all three traits, but the variability in LAI was related to a twofold difference between two developmentally distinct groups that did not differ in either CER or RGR. Although CER of all genotypes decreased at high density, the magnitude of the CER response to increased LAI differed. In both years, mean RGRs of plants in the twelve genotype ✕ density treatments were significantly correlated (P < 0.01) with mean CERs, and the genotype CER and RGR means from all data were also correlated (P < 0.05). That these correlated differences were not due to differences in photosynthetic area was shown by the superiority in CER (38%) and RGR (34%) of genotype PI 269810 over genotype PI 269770, even though the two genotypes did not differ in mean LAI.
Sink Manipulation in Wheat: Compensatory Changes in Kernel Size
Authors: Ma Y.‐Z. , MacKown C. T. , Van Sanford D. A.
Published: July 2010

Kernel size (KS), an important yield component of wheat (Triticum aestivum L.), depends on assimilate availability and the capacity of the kernel to use assimilates. The objective of this study was to evaluate the response of wheat cultivars with different KS (20 to 43 mg kernel −1,) to sink manipulation. Twenty cultivars grown at two locations were partially degrained by removal of all spikelets from one side of only one spike per plant. Control spikes were left intact. Partial degraining decreased kernel number (KN) by 51%. Relative compensatory kernel growth tended to increase with decreasing KS. However, the KS of five cultivars was unaffected by partial degraining, and the relative growth response of one small‐ and one large‐kernel cultivar each deviated markedly from the predicted response. Partial degralning enhanced kernel N of all cultivars, with an estimated 19 to 80% of the increase in KS attributed to greater accumulation of N compounds. For selected caltivars, the KS distribution and flag‐leaf abscisic acid (ABA) were determined to evaluate the relationship of sink size to these traits. Partial degraining altered KS distributions; for all but one of seven cultivars evaluated, partially degrained cultivars had the largest 5% of kernels and the single largest kernel. Compensatory kernel growth was unrelated to flag‐leaf ABA, indicating partial degraining had no adverse effects on assimilate supply related to excessive ABA levels in the flag leaf. These results demonstrate variable cultivar response to partial degraining; apparently, kernel growth of some cultivars is source limited, while other cultivars are at their capacity to accumulate assimilates.
Infection of Grasses by Barley Yellow Dwarf Viruses in California
Authors: Griesbach J. A. , Steffenson B. J. , Brown M. P. , Falk B. W. , Webster R. K.
Published: July 2010

Barley yellow dwarf viruses (BYDVs) continue to cause losses California cereal production. In some parts of the USA, native grasses have been implicated as reservoirs of BYDVs. This study examines the potential of native and irrigated pasture grasses as sources of BYDV inoculum in California. Theffects of both natural and natural plus supplemental inoculum were examined in field trials over two growing seasons using a completely randomized design. Results were assessed by enzyme‐linked immunosorbent assay (ELISA) and verified with controlled greenhouse vector transmission trials. Thirty‐seven of 56 species of cool‐season grasses were infected by either PAV, MAV, or RPV isolates of the BYDVs. Of the BYDV‐infected grasses, only 38% displayed symptoms typically seen in infected oat (Avena sativa L.) and barley (Hordeum vulgare L.), while the others were asymptomatic. None of the plants from seven species of Leymus, nor plants from the majority of Elymus and Elytrigia species, had detectable BYDV infections, even though they supported aphid vector populations. A survey of common grasses from irrigated pastures showed that plants from 6 of 10 species were infected by either the PAV, MAV, or RPV isolates of BYDVs. The incidence of MAV, PAV, and RPV BYDVs were roughly equivalent for the cool‐season grasses, but were highly skewed toward PAV in the irrigated pasture survey. Both cool‐season and irrigated warm‐season pasture grasses have the potential to serve as BYDV reservoirs in California.
Self‐Incompatibility in Two Alfalfa Populations
Authors: Bauchan G. R. , Campbell T. A. , O'Neill N. R. , Elgin J. H.
Published: July 2010

Self‐incompatibility provides a useful mechanism for pollination control in alfalfa, Medicago sativa L. Five hundred randomly selected seedlings from each of two well‐adapted multiple pest‐resistant alfalfa populations (W10 AC3 and BMP8 AC3) were screened for self‐incompatibility. Twenty‐eight plants were selected following three evaluations in the greenhouse. Unemasculated hand pollinations of the self‐incompatible plants, using plants with the singlegene, completely dominant red‐root character as the pollen source, resulted in the production of 98.6% hybrid seed. Plants were intercrossed in the greenhouse using honey bees, Apis melifera L. Growth chamber forage‐yield trials of half‐sib progenies indicate that certain combinations of self‐incompatible plants exist that will yield significantly better than the parent populations. Twelve elite self‐incompatible plants selected after the initial screening produced (i) < 0.15 seeds floret−1 when self pollinated, (ii) =30% viable pollen, and (iii) =3 seeds floret−1 when used as the male or female in crosses with other plants. Pollen‐pistil interaction studies of the self‐incompatible plants showed that the pollen had normal viability and either failed to germinate upon self pollination or pollen tube growth was abnormal. Pollen tubes that grew near the ovules either formed bulbous structures and terminated, or formed several branches, or continued to grow past all of the ovules resulting in the failure of fertilization. However, normal fertilization and good seed set were obtained when the self‐incompatible plants were used both as male and female in crosses with other plants. The 12 elite self‐incompatible plants were shown to have the capacity to produce somatic embryos in vitro, indicating that these plants could be propagated utilizing artificial seed technology. Evidence to date indicates that the use of the self‐incompatibility system may provide a mechanism for successfully producing high‐yielding hybrid alfalfa cultivars.