摘要:

AbstractThe effect of in vitro colchicine treatment of sugar beet ovules, after 7 days culture, on embryo formation, regeneration and ploidy of regenerated plants was studied with 5 concentrations of colchicine and 5 durations of treatment arranged as a 5 × 5 factorial in incomplete blocks. The best results were obtained with the shortest duration of treatment (5 hours) and the highest concentration of colchicine (0.4 %) giving 5.0 diploid plants per 100 ovules with 62.1 % of regenerated plants being diploid. Statistical analysis revealed that treatment effects could be separated into a toxic effect reducing embryo formation and a chromosome doubling effect affecting percentages of diploid regenerated plants. Toxic effects on embryo formation could be explained by simple exponential decay models, toxicity of the drug (decay constant) increasing linearly with duration of treatment. Duration of treatment had no effect on chromosome doubling percentages. The effects of colchicine concentration on chromosome doubling were explained by an exponential saturation model with spontaneous chromosome doubling of 8.1 % and saturation at 51.4 % diploid plants at 0.2 % and higher colchicine concentrations. In addition, treatments increased percentages of 4N and 6N plants from 0 % without colchicine to 10 % on average for treated ovules. A response surface model fitted to the total yield of diploid plants per ovule indicated that shorter durations of treatment and higher colchicine concentration may improve results

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00655.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractRespiration is responsible for much of the sucrose loss that occurs during sugarbeet (Beta vulgansL.) storage. Genotypes with reduced storage respiration rates would provide an efficient method for reducing sucrose losses. However, the current techniques for measuring storage respiration are not adapted easily to breeding programs. Internal CO2concentration has been recommended as an efficient method for measuring the respiration rate of individual sugar‐beet roots in storage. This study examined the effectiveness of internal CO2concentration as a selection criterion for reducing respiration rate of sugarbeet during storage. Lines resulting from four cycles of divergent selection for internal CO2concentration were evaluated along with commercial hybrids and low internal CO2germplasm lines. Selection was effective in shifting internal CO2concentration. Relative differences in internal CO2concentration were consistent throughout the 3‐year study. Neither the fourth‐cycle selections for low nor the fourth‐cycle selections for high internal CO2concentration were significantly different from the original population for evolved CO2. This lack of a close relationship between internal and evolved CO2indicated that internal CO2concentration is not an effective selection criterion in a breeding

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00656.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe economic evaluation of forage maize is complex due to its usage in different types of farms as well as the interdependencies of forage maize traits with the farm organization and the intensity of production. By means of linear programming, the economic weights of important forage maize traits were calculated for farming conditions in Germany. They were determined from the difference in the gross margins of farm models for given changes in a single trait of forage maize and were calculated for dairy and bull‐fattening farms under five levels of animal performance, three stocking rates, and different levels of forage maize traits. Individual economic weights under these settings varied little in most cases and allowed aggregation of mean economic weights. They amounted to 4.6ECUha−1for metabolizable energy yield (GJ ha−1), 207ECUha−1for metabolizable energy content (MJ kg−1), and 3.1ECUha−1for crude protein content (g kg−1). Economic weight for forage dry matter content was strongly dependent upon the maturity of the materials and varied between ‐5 and 25ECUha−1. The application of economic weights was discussed in comparison with other criteria for the assessment of experimental hybrids i

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00657.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSelection indices were calculated for simultaneous improvement of relevant forage maize traits. Beside indices based on primary traits [metabolizable energy yield (MEY) and content (MEC), crude protein content (CPC)] determined either in vitro or by near‐infrared reflectance spectroscopy (NIRS), we calculated indices based on secondary (five agronomic) traits. The required phenotypic and genotypic covanance matrices were estimated from a series with 120 maize hybrids tested at three sites. Base index, heritability index, optimum index, and restricted index showed only minor differences in the expected gain in total economic worth (ΔH) for the present agricultural conditions in Germany. CPC was the least important primary trait; selection for grain yield, the most suitable secondary trait, resulted in greater ΔH values than any other index. Harvesting the whole plant and subsequently determining MEC by NIRS was the most economic selection procedure with increased economic weighting for MEC at high animal performance levels. In the latter situation, we recommend grain yield trials as a pretest in breeding programmes and official performance trials for variety registrat

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00658.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractGenetic information is needed on maysin, a compound in maize,Zea maysL., silks that is antibiotic to corn earworm larvae,Helicoverpa(formerlyHeliothis)zea(Boddie), to assist in the process of breeding for resistance to this pest. This study was initiated to elucidate the inheritance of maysin content in the silks of a cross between two maize inbreds (GT114 and GT119) having resistance to the corn earworm. Reversed phase high performance liquid chromatography (HPLC) procedures were used to quantify the maysin concentration of silks from individual plants in the parent, F1, F2, and first backcross generations of the cross GT114 × GT119. A model assuming dominance at a single locus for low maysin content which is expressed only when a dominant modifier is present was proposed to explain the segregation ratios obtained in the F2and first back‐crosses of GT114 × GT119. This model also provided a fit for maysin data previously generated from a cross between inbreds F6 and F44. Observations of selfed families in the backcross of GT114 × GT119 to the low maysin parent confirmed the two‐locus model (one factor with dominance for low maysin expressed only when a modifier gene is also present) as a plausible explanation for inheritance of silk maysin in the cross. The process of selection for high maysin will be complicated somewhat by the presence of a gene which modifies the expression of dominance unless a method of easily identifying the gene, independent of maysin content, can be dev

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00659.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractYellow seededBrassica napuswas developed through interspecific crosses with the two mustard species,B. junceaandB. carinata.The objective of these two interspecific crosses was the introgression of genes for yellow seed colour from the A genome ofB. junceaand C genome ofB. carinatainto the A and C genomes ofB. napus, respectively. The interspecific F1generations were backcrossed toB. napusin an attempt to eliminate B genome chromosomes and to improve fertility. Backcross F2plants of the (B. napus×B. juncea) ×B. napuscross were then crossed with backcross F2plants of the (B. napus×B. carinata) ×B. napuscross. The objective of this intercrossing was to combine the A and C genome yellow seeded characteristics of the two backcross populations into one genotype. The F2generation of the backcross F2intercrosses was grown in the field, plants were individually harvested and visually rated for seed colour. Ninety‐one yellow seeded plants were identified among the 4858 plants inspected. This result indicated that the interspecific crossing scheme was successful in developing yellow seededB.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00660.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractScreening of a population ofOcimum basilicumvar.glabratumBenth., raised from seeds collected from France, West Africa and Kerala (India) was carried out for chemical composition of its essential oils. In all three collections, plants were found to be comprised of 3 chemotypes which were morphologically indistinguishable, but each chemotype was found to be capable of intercrossing freely with the other two.Selfing was carried out during 4 consecutive generations, after which three pure lines were established. Study of the selfed progeny of each collection exhibited an interesting segregation in S2and S3generations. Along with segregation in F2and F3generations of various hybrids the results can be explained by assuming a gene‘M’existing in 3 (or more) allelic forms: The alleleM0for biosynthesis of estragole (methyl chavicol) is dominant to allelcsM1, for eugenol andM2for camphor. Also, alleleM1is dominant to alleleM2. The assumption was further confirmed by testcrosses of F1hybrids of each cross with their recessive par

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00661.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract2483 almond seedlings developed from 42 crosses between 12 parents were studied for three years (1989, 1990 and 1991). General and specific combining ability was determined for six traits (all years) and eight traits (1989 only). Additive factors are largely responsible for the genetic control of all traits, non‐additive factors being of importance for the density of flowering and particularly for the density of production, time and duration of maturation and double kernels. The results permit the correct choice of parents and crosses for future breeding programmes and provide a better insight into the genetic control of the traits studie

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00662.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSchizaphis graminum(Rondani) is a serious pest of cultivated wheat (Triticum aestivumL.) and resistance is only available in other related species such asHordeum chilense.Amphiploids betweenH. chilenseandTriticumspp. have been obtained, and addition lines ofH. chilensein wheat have been developed.Thirty‐five accessions ofH. chilensewere screened to identify greenbug antixenosis, antibiosis and tolerance. Antixenosis was determined in a conventional host free choice test; antibiosis was measured by aphid life cycle and fecundity rate, and tolerance was tested in a conventional infestation test of 4 weeks. Two commercial barley cultivars were used as susceptible and resistant controls.EightH. chilenseaccessions showed higher degrees of antixenosis than the resistant check, 19 were similar and the rest were lower. All accessions were more resistant than the susceptible check. Measured by aphid life cycle, 22H. chilenseaccessions showed higher antibiosis than the resistant cv., and all exhibited a higher antibiotic effect on fecundity rates than the control. A similar degree of tolerance to that of the resistant control was observed in six accessions, the remaining entries ranged between the controls. The presence of one mechanism did not exclude the existence of other mechanisms in the same entry and therefore, independence of the different mechanisms is proposed.Most of the accessions showed higher variability than both controls for the three mechanisms, and it appears to be genetic variability within entries for the three mechanism

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00663.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractCallus induced from immature inflorescences of the partially self‐fertile hybrids (2 n = 35; ABDPP) betweenTriticum aestivum(2n = 42; AABBDD) andAgropyron desertorum(2n = 28; PPPP) led to the regeneration of 88 plants on MS medium supplemented with 2 mg/l of 2,4‐D. These regenerants were used to investigate somaclonal variation and to obtain more selfed derivatives. Immature inflorescences at the stage of developing floral primordia gave the best response in terms of callus induction and plant regeneration. The regenerants exhibited great variability for most morphological traits. Although the regenerants did not exhibit variation in chromosome number, they did show a higher degree of meiotic instability than the initial hybrid. In particular, the regenerants gave much higher selfed seed‐set (5.49 %) than the donor hybrid (0.46 %), so that a total of 484 selfed seeds were obt

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00664.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY