bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pollen Shedding and Combining Ability for High Temperature Tolerance in Rice1
Authors: Mackill D.J. , Coffman W.R. , Rutger J.N. 
Published: July 2010

High temperature‐induced sterility in rice (Oryza sativa L.) has not been an important problem in traditional cropping patterns. High temperature tolerance will become an important breeding objective as irrigation systems for dry season cropping are developed and rice production in semi‐arid countries expanded. A study was made to ascertain the prospects for breeding heat tolerant cultivars.A diallel cross experiment was conducted in the phytotron at the International Rice Research Institute to determine the combining ability of six rice lines for high temperature tolerance at anthesis. Control plants were kept under a 29/.21C temperature regime. The treated plants were subjected to 38/27 C for 10 days during anthesis. A heat tolerance index was calculated by dividing the percentage of filled grains of the treated plants by that of the control plants. General and specific combining ability effects for this index were highly significant. The tolerant lines, N22, IR2006 and IET4658, had general combining ability effects of 6.80, 4.08 and 3.02, respectively. The susceptible lines, IR28, IR1561 and IR52, had general combining ability effects of —3.40, —4.92 and —5.58, respectively.The amount of pollen shed on the stigma was studied for the six diallel parents and two F~ hybrids under the two temperature regimes (29/21 and 38/27 C). Tolerant cultivars shed more pollen grains on the stigma under both temperature regimes. In the susceptible genotypes, there was a marked reduction in the amount of pollen shed on the stigma at the high temperature. Pollen germination in the cultivar IET4658 was reduced under the 38/27 C temperature regime. Percentage fertility was positively correlated with the amount of pollen on the stigma at 38/27 C. The large amount of pollen on the stigma in tolerant genotypes appeared to compensate for reduced pollen growth under high temperature. Observations of pollen shedding under field conditions corresponded well with the phytotron results.
A New Method to Determine the Number of Genes for Resistance to Maize Dwarf Mosaic in Maize1
Authors: Scott Gene E. , Rosenkranz Eugen 
Published: July 2010

Information on the number of genes conditioning resistance to maize dwarf mosaic (MDM) will assist maize (Zea mays L.) breeders to choose the most appropriate breeding system for using these genes in their breeding program. Our objectives were (a) to devise a method for estimating the number of genes for resistance, (b) to determine the number of genes for resistance in five resistant inbreds, and (c) to ascertain if genes for resistance in different lines were in common.The proposed method for estimating number of genes utilizes data from two classes of plants (diseased and healthy) in different segregating generations to determine the number of alleles for resistance that allowed symptom expression under the conditions of the test. With these data and with the expected frequency of plants with a given number of alleles for resistance in these segregating generations, estimates of the number of genes for resistance in the resistant parent can be made.We found that inbreds GA209, Mp339, Mp412, T240, and Va35 had 2, 2, 2, 3, and 1 gene for resistance, respectively, to maize dwarf mosaic virus strain A. GA209 probably has one gene for resistance in common with Mp339. The gene for resistance in Va35 is different from both genes in Mp339.
Isoelectric Focusing of Esterases for Fine Fescue Identification1
Authors: Villamil C. B. , Duell R. W. , Fairbrothers D. E. , Sadowski J. 
Published: July 2010

There is a growing need for a technique to validate identities of commercial lots of seed, particularly at the cultivar level. A technique that would aid in identification of species and subspecies of a genus such as Festuca would also be helpful. The purpose of the present work was to develop such methods.Protein was extracted from ground and delipified seeds of cultivars or selections of known origin. Extracts were quantitatively added to polyacrylamide gel (with ampholite) in either rods or slabs and subjected to isoelectric focusing over a pH gradient of 4 to 9. After staining, up to 20 esterase bands. Isoelectric focusing on gel slabs provided a technique for simultaneous comparisons, both qualitative and quantitative, of band patterns of up to 18 entries side‐by‐side. Densitometric graphing aided in revealing consistent differences in relative density of specific bands, and made rapid identification of cultivars possible.Environmental stability of esterase band patterns characterizing cultivars was demonstrated using samples from the same seed fields for 3 years and also from different fields each year. Neither year of production nor location of production significantly altered the isozyme banding pattern that characterized each cultivar. Species and subspecies among the fine fescues were shown to encompass cultivars having similarities in esterase patterns that differed from those of other subspecies. Those illustrated include Festuca rubra subsp. rubra, F. rubra subsp. commutata, F. rubra subsp. trichophytla, F. tenuifolia F. ovina subsp. duriuscula = F. longifolia, and F. ovina subsp. glauca.We concluded that the esterase patterns developed were free from environmental influences and can be used satisfactorily for identification of fine fescue cultivars.
Response to Index Selection in Maize for Resistance to Ear Damage by the Corn Earworm1
Authors: Widstrom N. W. , Wiseman B. R. , McMillan W. W. 
Published: July 2010

Three selection indexes, 1) derived by standard procedures (RS), 2) derived from direct and correlated responses of the index traits (RI), 3) from direct and correlated responses of the primary trait (RSI), were compared with selection for reduced corn earworm [Heliothis zea (Boddie)] injury per se (CEW) through four cycles of selection in the maize (Zea mays L.) population RFC. Responses for reduced corn earworm injury occurred for all methods of selection, but the significant rates of response of RSI and RI selection were larger than RS or CEW. CEW and RI selections resulted in tighter husks, shorter husk extension, and slightly less yield reduction than in RS and RSI selections. None of the index procedures were superior to conventional selection for resistance to corn earworm, but the RI index was judged to compare most favorably when considering all trait responses.Phenotypic correlations obtained from S1 progeny data within each cycle indicated that the interrelationships among index traits, other than days to anthesis, had changed substantially during the course of four cycles of selection. The significant relationships of corn earworm injury with husk tightness and husk extension were greatly reduced and significant reversals of the relationship between husk tightness and extension occurred among the RS and RSI selections. The RI index will be revised for further comparison with conventional selection in this maize population for reduced injury by the corn earworm.
Association of N‐acetyl Loline and N‐formyl Loline with Epichloe typhina in Tall Fescue1
Authors: Bush L. P. , Cornelius P. L. , Buckner R. C. , Varney D. R. , Chapman R. A. , Burrus P. B. , Kennedy C. W. , Jones T. A. , Saunders M. J. 
Published: July 2010

The alkaloid fraction of tall rescue (Festuca arundinacea Schreb.) has been implicated in poor forage quality but the alkaloid content of tall rescue varies greatly amongrazing seasons, pastures, and individual plants. The objective of this research was to identify the association between the presence of E. typhina (Fr.) Tul. in the plant and the N‐formyl and N‐acetyl loline alkaloids. Plants were grown in benomyl‐treated soil in the greenhouse to control the fungus and treated plants and seed from treated plants were established in the field to provide seed and plant tissue for analysis. The fungus was eliminated or its development severely inhibited by growing tillers for 6 weeks in soil treated with benomyl.Accumulation of N‐acetyl loline and N‐formyl lollne in tall fescue was positively associated with the presence of the endophytic fungus, Epichloe typhina. Leaf tissue from treated plants contained very small amounts of N‐acetyl or N‐formyl loline. Plants from which E. typhina had been eliminated and that had been established in the field remained free of the fungus for at least 3 years.
Changes in Soybean Seed Oil and Protein as Influenced by Manganese Nutrition1
Authors: Wilson D. O. , Boswell F. C. , Ohki K. , Parker M. B. , Shuman L. M. , Jellum M. D. 
Published: July 2010

Manganese deficiency is known to severely reduce growth and yield of soybean [Glycine max (L.) Merr.] plants, but little is known about the effects of Mn deficiency on soybean seed quality factors. Seed from field‐grown soybean plants containing leaf Mn concentrations ranging from 4 to 58 ppm were analyzed for oil and protein percentage. Seed oil and seed protein from selected treatments containing 4 to 44 ppm leaf Mn were analyzed for fatty acid and amino acid percentages, respectively.Severe Mn deficiency (less than 15 ppm Mn in the leaves) increased seed protein percentage and decreased seed oil percentage. Seed from plants with extremely low leaf Mn levels contained higher percentages of linoleic, palmitic, linolenic, and stearic acids and a lower percentage of oleic acid. The percentages of seed protein, seed oil, and fatty acids changed markedly at low leaf Mn levels but remained relatively constant above leaf Mn concentrations of 15 to 20 ppm. Percentages of amino acids in seed protein were relatively unaffected by Mn.The results show that several soybean seed quality factors can be markedly altered by deficient levels of Mn. These changes could have a significant influence on the quality of products derived from soybean seed.
The Effect of Rhizobium trifolii Strains and Crimson Clover Genotypes on N2 Fixation1
Authors: Smith G. R. , Knight W. E. , Peterson H. L. , Hagedorn C. 
Published: July 2010

The effects of crimson clover (Trifolium incarnatum L.) genotype and strain of Rhizobium trifolii on dry weight yield and N2 fixation were investigated in a factorial experiment. The treatments were arranged in a randomized complete block design with eight replications. The clover‐Rhizobium combinations were grown in plastic pouches with a N‐free nutrient solution. A growth chamber was used to maintain 24/19 C diurnal temperatures and a 12 hour photoperiod.After 60 days of growth, the combinations were assayed for N2 fixation using acetylene reduction and the plant tops were harvested and dried. Plant lines, strains of Rhizobium and line ✕ strain interaction were all significant sources of variation for both acetylene reduction rate and dry weight yield. Strains had the largest effect, in terms of variance components, on dry weight yield followed by plant lines and strain ✕ line interaction, respectively. Strains also had the largest effect on acetylene reduction rate followed by strain ✕ line interaction and plant lines, respectively. Strain TA1 of R. trifolii was highly variable in its effect on the different plant lines. Response of different inbred lines with this strain ranged from efficient to inefficient.
Quantitative Inheritance of Ozone Resistance in Potato1
Authors: De Vos N. E. , Hill R. R. , Pell E. J. , Cole R. H. 
Published: July 2010

The inheritance of foliar resistance to ozone was studied in 14 cultivars of Solanum tuberosum L. using two sets of 7 × 7 diallel crosses. Resistant, intermediate, and susceptible parents were included in each diallel. In each of four runs for each diallel, parent clones, parents selfed, and reciprocal F1 hybrids were simultaneously exposed to 774(μg/m3 (0.40 ppm) ozone for 3 hours in a controlled environment chamber at 21 C and 70% relative humidity.General and specific combining ability were significant in both diallels, accounting for over 70 and 20%, respectively, of the variation among hybrids. Maternal effects were significant in one diallel, but accounted for less than 5 % of the variation among hybrids in either set of crosses. Single‐locus, autotetraploid genetic models for complete additivity, complete dominance for suceptibility, and complete dominance for resistance were tested by comparing the observed and expected relationships between parent, S1, and offspring means. Complete dominance for resistance accounted for the results better than any of the simple models tested; however, no adequate test for digenic and trigenic models could be determined, and no model with more than one locus or multiple alleles was examined.
Genotype ✕ Environment Interactions for Leaf Area Parameters and Yield Components and Their Effects on Wheat Yields1
Authors: Borojevic Slavko , Williams William A. 
Published: July 2010

Genotype × environment interactions for parameters characterizing source and sink capacity and their effects on grain yield of three divergent wheat (Triticum aestivum L.) cultivars were studied over a 10‐year period.The mean square in the number of spikes/m2 due to genotype × year interaction (g × y) was greater than the mean squares due to years or genotypes alone. The mean square for leaf area index (LAI) and leaf area duration (LAD) due to years was greater than the mean squares due to genotypes and g × y interactions. The mean squares due to genotypes were greater than the mean squares for years and g × y interactions for number of kernels/spike, 1,000‐ kernel weight, disease and lodging resistance, as well as for grain yield. Environmental factors exhibited greater effects on the parameters of source capacity than on the parameters of sink capacity.The LAD showed the highest positive relative contribution to grain yield for each cultivar over the 10‐year period. Direct effects of other variables differed among the cultivars; some exhibited positive and some negative direct effects on grain yield. Using seven variables, 83% of variation of grain yield could be “explained” for the cultivar ‘Sava,’ 75% for ‘Bezostaia,’ but only 34% for ‘Bankut,’ as shown by the coefficient of determination.For climatic variables the only significant relation was a positive association between grain yield and hours of sunshine in May and June, i.e., during gamete formation, fertilization, and the grain filling period.Bezostaia showed the greatest stability in yield performance, but Sava gave the highest grain yield in all years. Since a grain producer is interested in having high grain yields at his location, the preference in the choice of cultivars should be given to the meangrain yield rather than to the other stability parameters.
Genotype ✕ Year Interaction for Length and Rate of Grain Filling in Oats1
Authors: Wych R. D. , McGraw R. L. , Stuthman D. D. 
Published: July 2010

In spring oats (Avena sativa L.) the sensitivity of grain yield to environmental stresses during grain filling varies among genotypes that differ in days to heading. The main objective of this study was to evaluate the relationship between grain yield, grain‐filling rate (GFR), and grain‐filling period (GFP) of oats in two contrasting field environments. A secondary objective was to assess the validity of estimating “vegetative growth rate” (i.e., preheading crop growth rate) from straw weight at maturity and days to heading.Twenty oat genotypes selected for diversity in days to heading and percent groat protein were grown in consecutive years that differed in air temperature during the GFP and in rainfall distribution during the growing season. Average grain yield in 1980 was 8% lower than in 1979. The genotype × year (G × Y) interaction for grain yield resulted from increases from 1979 to 1980 for earlier heading genotypes but decreases from 1979 to 1980 for later heading genotypes. Compared to 1979, the 1980 GFP was shortcned for all genotypes, but was changed the most for later heading genotypes. Relative to 1979 values, GFR in 1980 increased for 12 of the earlier heading genotypes, but decreased for six of the eight later heading genotypes. Kernel weight and groat percentage were also lower in 1980 than in 1979 for all 20 genotypes, supporting the interpretation that kernel growth, and hence grain filling, were curtailed prematurely in 1980.Straw weight declined between heading and maturity for only one genotype in 1979 but for seven genotypes in 1980. Since the occurrence and magnitude of post‐heading change in straw weight are subject to G × Y interaction, vegetative growth rates estimated by dividing straw yield at maturity by days to heading may be invalid. Two alternate methods for more accurately estimating vegetative growth rate are discussed.
Genotype × Environment Interactions for Protein in Glycine max × Glycine soja crosses1
Authors: Erickson L. R. , Beversdorf W. D. , Ball S. T. 
Published: July 2010

One hundred fifteen F3 families chosen from four crosses between Glycine max (L.) Merr. and its wild relative, Glycine soja Sieb. and Zucc., were used in two studies to evaluate the effect of genotype × environment interactions on the protein content of soybean seeds. The families ranged in protein content from approximately 40 to 50%.The first study was a variance component approach composed of 15 F3 families grown at two locations in 2 years. The family variance component estimate was highly significant (p≤0.01). Estimates of the variance components for the family × year and family × location interactions were nonsignificant. The estimated variance component for the family × year × location interaction was significant (p≤.05), although approximately one‐fourth the magnitude of the family and within‐plot variance components. Broad sense estimates of heritability for protein content calculated on a single plant, plot, and entry‐mean basis were 0.45, 0.58, and 0.90, respectively.The second study was composed of 100 F3 families conducted at two locations during a single growing season. Highly significant (p≤0.01) differences among the families were observed. Despite a highly significant (p≤0.01) correlation for protein content between locations, a few families with high protein content at one location had much lower protein content at the other location.Progress from selection among the families from these four crosses for protein content should be possible. Although the lower 50% of the families could be safely discarded on the basis of data from one location, selection among the higher protein genotypes should involve at least two environments.
Genetic Resistance and its Residual Effects for Control of the Root‐Knot Nematode‐Fusarium Wilt Complex in Cotton1
Authors: Shepherd Raymond L. 
Published: July 2010

Two cotton (Gossypium hirsutum L.) cultivars and a breeding stock (‘Deltapine 16’, ‘Auburn 56’, and Auburn 623 RNR, respectively), having in order low, intermediate, and high resistance to the root‐knot nematode‐fusarium wilt disease complex [caused by Meloidogyne incognita acrita (Kofoid & White) Chitwood and Fusarium oxysporum Schlecht. f. vasinfectum (Atk.) Snyd. & Hans.], were grown in nematicide, DBCP (1,2‐dibromo‐3‐chloropropane), treated vs. untreated plots for 3 years.Fumigation did not significantly increase lint yield of Auburn 623 RNR compared with 36 and 77% increases for Auburn 56 and Deltapine 16, respectively. Auburn 623 RNR without fumigation was more effective for controlling root‐knot nematodes than Auburn 56 and Deltapine 16 with fumigation and was equally effective as those cottons with fumigation for controlling fusarium wilt disease. In unfumigated plots, Auburn 623 RNR vs. Auburn 56 and Deltapine 16 also had lower root‐knot nematode numbers (83/500‐cm3 of soil vs. 717 and 1,581, respectively) and lower fusarium wilt percentages (5% vs. 47%, respectively). In the fourth year of the study, susceptible ‘Stoneville 213’ cotton was grown without fumigation in all plots where the above cottons had been grown. Stoneville 213 following unfumigated Auburn 623 RNR had 147 kg/ha (21%) and 270 kg/ha (47%) higher lint yields than following unfumigated Auburn 56 and Deltapine 16, respectively. Stoneville 213 had smaller root‐knot nematode populations following unfumigated Auburn 623 RNR than following fumigated Deltapine 16 and no greater incidence of fusarium wilt disease than when it followed fumigated Auburn 56 and Deltapine 16. If the high level of resistance exhibited by Auburn 623 RNR can be bred into cotton cultivars, it should reduce much of the present root‐knot nematode and fusarium wilt damage to cotton and to susceptible crops following resistant cotton in rotations.
Visible Indicators of Phsiological Maturity Barley1
Authors: Copeland Philip J. , Crookston R. Kent 
Published: July 2010

Visible indicators of maturity have recently been identified for several agronomic crops. Both researchers and farmers have been able to make use of these indicators. We conducted field experiments to identify visible indicators of physiological maturity (PM) in barley (Hordeum vulgare L.). Two cultivars in 1981 and six cultivars in 1982 were selected to represent a diversity of morphological types and genetic backgrounds. Physiological maturity was defined as the attainment of maximum kernel dry weight and was identified by determining the apex of a cubic polynominal curve fitted to kernel dry weight data. Visible changes in the barley plant were evaluated for consistency and closeness to date of PM and to date of 95% maximum kernel dry weight (MKW).Loss of green color from the glumes and from the peduncle coincided most closely with PM. Loss of green color from the peduncle was more readily observable in the field. First appearance of the pigment strand in the kernel crease, thought to be analogous to black layer development in corn (Zea mays L.), occurred between −1 and 4.5 days after PM. Loss of green color from the flag leaf blade occurred close to the date of 95% MKW. Average percent kernel moisture at time of 9% MKW ranged from 45 to 50% at PM from 18 to 39%.
Evaluation of S2 Maize Lines Reproduced for Several Generations by Random Mating within Lines. II. Comparisons for Testcross Performance of Original and Advanced S2 and S8 Lines
Authors: Carlone M. R. , Russell W. A. 
Published: July 2010

An alternative to the use of highly inbred lines to produce maize hybrids (Zea mays L.) would be to use lines that have been only partly inbred, selected in early generation testing for their combining, ability, and maintained by randomating within lines (sib‐mating). Our objective was to compare the testcross performance of original S2 lines with their maintained S2‐1ine counterparts and S2‐line derivatives to determine if changes have occurred in the S2 lines after several generations of sib‐mating or S8 lines after further inbreeding.We evaluated the performance of 14 original S2 lines; each S2 line maintained by using 10 and 20 plants generation −1, four lines also maintained by using mild selection for agronomically desirable traits, and their Ss line derivatives in testcrosses with two unrelated testers. Significant (P < 0.05) or highly significant (P < 0.01) differences among groups were observed for 8 of the 14 traits evaluated; grain yield differences were nonsignificant. Individual comparisons between each original S2 line and its maintained S2‐1ine counterparts showed that significant differences occurred in both the positive and negative directions for many traits, thus indicatingenetic changes. Testcrosses of S2 lines maintained by using 10 plants generation −1 generally tended to be less stable than if they were maintained by using 20 plants. For grain yield, only one maintained S2 line differed significantly from its original S2‐line counterpart, whereas three S8 lines showed a significant change. Thus, maintaining S2 lines by sibmating by using 10 or 20 plants, or mild selection, had small effects on the combining ability of the individual S2 lines.