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1.
J. Atlagi&#; 《Plant Breeding》1996,115(4):257-260
Hexaploid sunflower species provide potential sources of desirable genes in breeding for resistance to pathogens as well as high protein and oleic acid content. The possibility of using them in sunflower breeding was studied by testing the crossability of hexaploid species to cultivated sunflower, by the analysis of meiosis and pollen viability in the F1 interspecific hybrids. The hybrids were obtained from 16 combinations, with 1–18 F1 plants per combination. The F1 hybrids in general exhibited the dominant phenotype of the wild species. Sterility ranged from 0 to 87.5% per F1 combination, while pollen viability ranged from 43.0 to 70.2%. Meiosis was almost normal in the species analysed but irregular in the F1 hybrids. Most of the meiocytes showed predominantly bivalents (86.79–90.22%), but univalents (0.00–4.99%) and the multivalents (8.23–10.09%) occurred as well. At anaphase I, chromosome bridges were detected in 6.88–8.48% of meiocytes. Fast chromosomes in meta-phase I and lagging chromosomes in anaphase I and telophase II were observed in many meiocytes. 相似文献
2.
Meiosis and Pollen Viability in Helianthus tuberosus L. and its Hybrids with Cultivated Sunflower 总被引：1，自引：0，他引：1
The hexaploid species of Helianthus tuberosus is a potential source of resistance to several sunflower pathogens. But crossed with cultivated sunflower, it produces F, hybrids which have low values of fertility or even full sterility. Pollen viability and meiotic features were studied in 17 populations of the species H. tuberosus and in F1 hybrids. Significant differences in pollen viability existed between populations (47.1–98.8%). In the 15 FI hybrids, plant fertility ranged from 0 to 100 per combination, while pollen viability ranged from 12.4 to 57.1. Meiosis was almost normal in the analyzed species, and irregular in the F, hybrids. The highest percentage of meiocytes was with bivalents (85.9), but univalents (0.3) and multivalents (13.8) occurred as well. In metaphase and anaphase, the percentage of meiocytes with fast and lagging chromosomes was high. In anaphase, chromosome bridges were detected in 9.9 of the meiocytes. 相似文献
3.
Summary Three non-tuberous Solanum species of series Etuberosa-S. brevidens (brd), S. etuberosum (etb) and S. fernandezianum (frn)-upon selfing displayed compatible berry set but seed set varied and on an average was below normal. Also in crosses between species berry set was unhampered (apart from the crosses with short-styled frn as pollen plant), but the interspecific hybrid plants showed various degrees of sterility and a low average seed set upon selfing. Cytological investigations revealed that in pure species-plants semi-sterility regularly occurred and was invariably associated with multivalent associations (up to decavalents). This may account for the decreased seed set found after selfing and intercrossing. Meiosis in F1-hybrids was even more irregular, 75% of the pmc's showing multivalents involving from 4 to as many as 22 chromosomes in various complicated configurations in which even numbers of chromosomes were predominant. However, anaphase I separation was numerically balanced in more than 75% of the cells. Pollen stainability was very low in the hybrids.It is concluded that heterozygous translocations occur within each species and that the genomes of the species are differentiated by means of gross structural changes. In view of this and of the high chromosome pairing affinity the genome symbols E
1, E
2 and E
3 are proposed for etb, brd and frn, respectively.Crossability of the Etuberosa species with tuberous S. pinnatisectum (pnt) was slightly more successful (average 2.7 seeds/berry) than that of Etuberosa species hybrids with S. pinnatisectum (average 1.7 seed/berry). In the hybrids studied-etb × pnt, frn × pnt and (brd × etb) × pnt-a high frequency of univalents was the rule (range 6–16 per cell). In addition rod bivalents (4–8 per cell) and a low frequency of trivalents occurred (0–3 in the biparental hybrids and 1–4 in the trispecific hybrid).Utilization of the valuable characters of Etuberosa for potato breeding is dependent on the degree of gene exchange between Etuberosa chromosomes and chromosomes of tuberous species. In the diploid hybrids such exchange, though limited, may take place through bivalents and trivalents. As shown in this article such diploid hybrids are non-crossable because of complete male and female sterility. Only after doubling the number of chromosomes the hybrids are fertile and can be used for further crosses. 相似文献
4.
Although the wild sunflower species Helianthus laevigatus has not been extensively studied it may be considered for sunflower breeding as a potential source of desirable genes for Sclerotinia stalk rot resistance and high contents of proteins and linoleic acid in the seed. A set of six H. laevigatus populations was crossed to cultivated sun~ower lines and produced nine F1 (2-14 plants) and 66 BC1F1 hybrid combinations (1-13 plants). Male sterility occurred in F1 and BC1F1 hybrid combinations and pollen viability was lower in the progenies than in the parents (51.6-77.2%in F1 and in F1 and 4.8-34.0% in BC1F1). Meiosis was normal in the H. laevigatus populations It was found that this tetraploid species also occurred in a hexaploid form Numerous irregularities were observed in the meiosis of the F1 interspecific hybrids During diakinesis, quadrivalents and hexavalents were recorded in addition to bivalents Dislocated chromosomes and chromosome bridges were present in the other phases The chromosome number in F1 was 68 (tetraploid). Irregularities in chromosome pairing were observed in the interspecific hybrids at BC1F1. There were many univalents, and trivalents quadrivalents and hexavalents were also present The chromosome number in the BC1F1 generation ranged from 34 to 60. The occurrence of meiotic irregularities in the F1 and BC1F1 interspecific hybrids indicates that H. laevigatus and the cultivated sunflower differ in genome constitution. 相似文献
5.
The first success at interspecific hybridization between cultivated sunflower(H. annuus) and a diploid perennial species, H. simulans is reported. The F1s from both direct and reciprocal directions exhibited dominance of the wild species phenotype and were pollen sterile. Meiosis
was irregular in the F1 hybrids and both univalents and multivalents were observed. Multiplication of the interspecific hybrids was achieved through
in vitro culture of nodal sections on Murashige & Skoog medium supplemented with 0.5 mg l-1 benzyladenine. Fertility of the interspecific hybrids was improved by subjecting the in vitro proliferating shoots to 0.001% colchicine incorporated in the shoot multiplication medium. The amphiploids serve as fertile
bridges and facilitate interspecific gene transfer through conventional breeding.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Summary Meiosis was studied in some triploid, tetraploid and hexaploid F1-hybrids from Solanum acaule x S. bulbocastanum and in a triploid F1-hybrid from S. acaule x S. tuberosum-haploid.The only anomaly found was stickiness at metaphase I, the degree of which appeared to be related to the proportion of the S. bulbocastanum chromosomes in the hybrids. No stickiness occurred at pre- and post-metaphase stages.A clear allosyndetic pairing between chromosomes of the two S. acaule genomes was observed in all triploid and tetraploid hybrids. These genomes apparently are closely related and little differentiated. The triploids S. acaule x S. bulbocastanum had 0–1 trivalent per cell, whereas 2–5 trivalents per cell were observed in the triploid S. acaule x S. tuberosum-haploid. Therefore S. acaule is more closely related to S. tuberosum L. than to S. bulbocastanum. A small amount of pairing between S. acaule and S. bulbocastanum is apparent from the occurrence of multivalents in all hybrids.Hexaploid F1's (2n=72) showed a nearly complete homologous pairing of chromosomes (35.2 bivalents per cell) and generally a normal separation of chromosomes at anaphase: 36-36. This offers an explanation for their high fertility. Triploid F1's from S. acaule x S. bulbocastanum have a high frequency of univalents leading to irregular separation of chromosomes at anaphase and consequently to unbalanced gametes and extreme sterility. In the tetraploid F1's (2n=48) nearly complete bivalent pairing was observed, 50% expectedly being homologous and 50% homoeologous pairing. Separation of chromosomes at anaphase was generally normal 24-24. In spite of this normal behaviour and allowing for tight stickiness at metaphase the tetraploids are very sterile. A satisfactory explanation cannot yet be given.Selfing and intercrossing hexaploid F1's gives normal berry set and many seeds per berry. However crosses with S. tuberosum and even those with the fertile hexaploid hybrid from 8x-S. acaule x 4x-S. tuberosum are little successful: berry set is far below normal and the berries are either parthenocarpic or contain only one or two seeds. These rather unexpected results warrant further investigation. Large-scale selfings and intercrosses of triploid and tetraploid hybrids have not been successful as yet. Among the female gametes of tetraploid hybrids a few appeared to be functional in crosses with hexaploid hybrids and in those with S. bulbocastanum. 相似文献
7.
Summary
Helianthus petiolaris is a wild species used in genetic improvement of sunflower, as a donor of cytoplasmic male sterility and of genetic resistance to diseases. Isozyme variation for ADH, ACP, EST, GDH, LAP, PGI, PGD and SKDH in this species was studied using starch gel electrophoresis. The patterns thus obtained were compared with zymograms of inbred lines, hybrids and open pollinated varieties of H. annuus. The same alleles for EST and SKDH isozymes were found in both species, while ACP showed an allele that has not been found in sunflower. The rest of the isozyme systems showed both common alleles and characteristic ones for each species. ACP, GDH and PGD were monomorphic in H. petiolaris, while ADH and LAP were monomorphic in H. annuus. The isozyme markers obtained here could be useful in breeding programs involving interspecific crosses, and studies on introgression and on genetic variation in other populations of this wild species. 相似文献
8.
N. Inomata 《Euphytica》2003,133(1):57-64
The cytogenetic study was investigated in the intergeneric F1 hybrid, F2and backcross progenies (BC1). The plants used were Brassica juncea(2n=36) and Diplotaxis virgata(2n=18). Three intergeneric F1 hybrids between two species were produced through ovary culture. They showed 36 chromosomes. It might consist one genome
of B. juncea and two genomes of D. virgata. The morphology of the leaves resembled that of B. juncea. The color of the petals was yellow that was like in D. virgata. The size of the petal was similar to that of B. juncea. The mean pollen fertility was15.3% and the chromosome associations in the first meiotic division were(0–1)IV+(0–2)III+(8–12)II+(12–20)I. Many F2 and BC1seeds were harvested after open pollination and backcross of the F1 hybrids withB. juncea, respectively. The F2seedlings showed different chromosome constitutions and the range was from 28 to54 chromosomes. Most seedlings had 38chromosomes
followed by 36, 40 and 54. The BC1 seedlings also showed different chromosome constitutions and the range was from 29 to 62. Most seedlings had both 40and 54
chromosomes followed by 36, 46 and52. In the first meiotic division of F2 and BC1 plants, a high frequency of bivalent associations was observed in all the various kinds of somatic chromosomes. Many F3 and BC2 seeds were obtained by self-pollination and open pollination of both F2 and BC1 plants, and by backcrossing both F2 and BC1plants with B. juncea, respectively,especially, three type progeny with 36, 40or 54 chromosomes. The somatic chromosomes of the F3 and BC2 plants were further investigated. The bridge plants between B. juncea and D. virgata with 36 chromosomes may be utilized for breeding of other Brassica crops as well as B. juncea.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Spodoptera litura (Fabr.), the tobacco caterpillar, is a major defoliator on sunflower in the tropics. Genetic variability for resistance to
S. litura is limited in the cultivar germplasm of sunflower. In the present investigation, 43 accessions of 17 wild Helianthus species of the annual and perennial habit groups were evaluated along with cultivated sunflower under field and no-choice
conditions in the laboratory for resistance to this pest. Under field conditions, H. occidentalis and H. argophyllus were found to be immune with no leaf damage and few accessions of the species belonging to section Divaricati were found
to be resistant. Laboratory bioassays against neonate, two and 4-day-old larvae confirmed resistance both in terms of high
larval mortality and low larval weight gain in eight species viz., H. occidentalis, H. argophyllus, H. tuberosus, H. maximiliani, H. mollis, H. simulans, H. divaricatus and H. hirsutus. Intra-accessional variability was observed and accessions of few species showed varied reaction (resistant, partially resistant
to susceptible) to the target pest. Field evaluation of 224 backcross derived inbred lines from five cross combinations involving
diploid species under high natural pest incidence revealed low damage in plants derived from crosses involving H. argophyllus and H. petiolaris. 相似文献
10.
Interspecific hybrids and backcross generations between the wild perennial species Helianthus resinosus, Helianthus paucifiorus, Helianthus laevigatus, Helianthus nuttallii ssp. nuttallii T. & G. and Helianthus giganteus, resistant to broomrape (Orobanche cernua) and susceptible inbred lines were obtained to study crossability to cultivated sunflower and the transmission and expression of resistance to this parasitic weed. Conventional crosses with all the species tested were successful except for the crosses with diploid H. giganteus, for which embryo rescue techniques were needed to overcome hybrid incompatibility. Pollen viability and seed set were highest for F1 hybrids with hexaploid species and lowest for those with the diploid H. giganteus. We evaluated F1, BC1F1, some BC2F1 plants and the wild and cultivated parents. The wild species and interspecific hybrids were resistant to broomrape infection except for H. nuttallii, which showed segregation, indicating that the resistance is dominant. The crossability and resistance of F1, and back-cross generations of species with different ploidy levels indicate that the transfer of broomrape resistance to cultivated sunflower is feasible. 相似文献
11.
Successful selection of interspecific hybrid progenies with superior ability to regenerate shoots from apical meristems was
performed in sunflower which now allows for the development of lines for improved biotechnological applications. Early generations
of interspecific hybrids originating from crosses between the two H. annuus CMS lines ‘HA89’ and ‘Baso’, and 9 wild species were screened for their ability to regenerate in vitro. Evaluation of 36 progenies allowed to identify seven progenies from crosses involving H. mollis, H. giganteus, H. strumosus, and H. decapetalus which showed a significantly higher regeneration potential than the commercial hybrid ‘Albena’ regarding the number of shoots
per explant. Among these progenies, 47.2 to 62.4% of explants produced shoots with an average of 2.3 to 3.5 shoots per cultured
explant. Regeneration in vitro was significantly determined by the genotype. More than half of the investigated interspecific hybrids performed better than
the inbred ‘HA89’ demonstrating that the high regeneration potential available in the wild species can be efficiently transferred
to cultivated sunflower. The seven progenies with high regeneration potential in vitro were characterised by agronomic performance in the field. Two of the interspecific hybrids derived from H. strumosus and H. decapetalus not only showed a superior regeneration potential but also proved to be competitive to commercial hybrids with regard to
important agronomic traits, e.g. fat content and TGW.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
Sunflower downy mildew caused by Plasmopara halstedii is an important disease of sunflower capable of causing losses of more than 80% of production. Races 100, 300, 310, 330,
710, 703, 730 and770 of the fungus have been identified in Spain. Race 703, of high virulence, has been identified frequently
in the northeast, while race 310 seems to occur over the south, the main sunflower growing region of the country. Oil sunflower
lines RHA-274 and DM4 were studied for their resistance to races 310(RHA-274 and DM4) and 703 (DM4). In each cross, only one
plant of the resistant parent was crossed to the inbred susceptible line HA-89 (or cmsHA-89).Plants from F2 and backcross(BC1F1 to susceptible parent)generations were evaluated for fungal sporulation on true leaves and/or cotyledons. The resistant-to-susceptible
ratios obtained in the F2 and BC1F1 progenies from the crosses cmsHA-89 × RHA-274 and HA-89 × DM4suggested that one major gene in each line is responsible for
resistance to race 703.The segregations of the progenies of the cross HA-89 × DM4 inoculated with race 703also fitted the
ratios 1:1 and 3:1 (for BC1F1 and F2, respectively)corresponding to control of resistance by a single dominant gene. In RHA-274, the gene for resistance to race
310 was designated Pl
9, whereas Pl
v is tentatively proposed to designate the gene in DM4 responsible for resistance to races310 and 703.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
Ernest D. P. Whelan 《Euphytica》1979,28(2):297-308
Summary Interspecific substitutions of the nucleus of Helianthus annuus (2n=34) into the cytoplasm of H. petiolaris (2n=34) were obtained by successive backcrossing using cultivated sunflower, H. annuus, as the recurrent pollen parent.Meiosis in the F1 was characterized by multivalents, suggesting that 10 of the 34 chromosomes were heterozygous for chromosomal interchanges. An additional pair of chromosomes also contained a paracentric inversion. Continued backcrossing resulted in rapid elimination of the meiotic aberrations evident in the F1. In the BC1, 1 of 11 plants had normal meiosis and by the BC2, only 13 of 54 plants had meiotic aberrations similar to those of the F1. However, trisomic progeny (2n=35) were found in 3 of the 11 BC1 plants and 20 of the 54 BC2 plants. No meiotic aberrations were observed in BC3 or BC4 plants. Plants with indehiscent anthers, and considered to be male sterile (M.S.), first occurred in the BC1 and, by the BC2, 51 of 54 plants were M.S. All 19 BC3 and 16 BC4 plants were M.S. Preliminary investigations suggest that the pollen from such plants is sterile and that the sterility is cytoplasmic rather than genetic.Disc-flower measurements were a useful technique for selecting samples at the correct stage of microsporogenesis, but could not be used to distinguish between successive backcrosses. 相似文献
14.
Summary A self-fertile trigeneric hybrid in the Triticeae involving species from the Hordeum, Triticum and Secale genera has been produced. The trigeneric hybrid was obtained by crossing octoploid triticale (x Triticosecale Wittmack) with octoploid tritordeum (H. chilense × T. aestivum amphiploid). The trigeneric hybrid presented a genome constitution AABBDDRHch and 2n=8X=56 chromosomes. The cytogenetical analyses showed no chromosome instability nor homeologous pairing between Hordeum and Secale chromosomes. In the F2 generation the chromosome number ranged from 42 to 52. Within this range, the plants with smaller numbers of chromosomes were more frequent. A preferential transmission of rye chromosomes could be inferred. 相似文献
15.
Liguleless phenotypes of wheat lack ligule and auricle structures on all leaves of the plant. Two recessive genes principally control the liguleless character in tetraploid wheat. The F2 progenies of k17769 (liguleless mutant)/Triticum dicoccoides and k17769/T. dicoccum segregated in a 15:1 ratio, whereas the F2 progenies of k17769/T. durum and k17769/T. turgidum segregated in a 3:1 ratio. A new gene, lg3, was found on chromosome 2A. Segregation of F2 progenies between k17769 and chromosome substitution lines for homoeologous group 2 chromosomes suggested that the liguleless genotype had occurred by mutation at the lg3 locus on chromosome 2A, and then by mutation at the lg1 locus on chromosome 2B, in the process of domestication of tetraploid wheat. The gene (lg1) was linked to Tc2 (11.9 cM), which determines phenol colour reaction of kernels, on the long arm of chromosome 2B. The distance of lg1 to the centromere was found to be 60.4 cM, and microsatellite mapping established the gene order, centromere – Xgwm382 – Xgwm619 – Tc2 – lg1 on the long arm of chromosome 2B. 相似文献
16.
Sunflower (Helianthus annuus L.) productions reliance on a single source of cytoplasmic male sterility, PET1, derived from H. petiolaris Nutt., makes the crop genetically vulnerable. Twenty diverse cytoplasmic substitution lines from annual and perennial wild species were compared with the inbred line HA89 over four environments. Pairwise comparisons of alloplasmic male fertile (MF) with euplasmic MF lines suggested that cytoplasm of perennial H. angustifolius increased lodging while perennial cytoplasms of H. mollis, H. grosseserratus, and H. divaricatus reduced head size and consequently reduced yield and will need to be used with caution. Lines having annual species, cytoplasms had no effects on agronomic traits. Comparisons of CMS HA 89 with 10 CMS lines suggested yield‐reducing cytoplasmic effects of perennial H. maximiliani and annual H. annuus PI 413178 and PI 413024. Cytoplasmic effects on oil percentage and fatty acid composition were minimal and should not be of concern for sunflower breeders. In general, most cytoplasms of wild annual Helianthus species accommodate cultivated nuclear genes without drastic adverse interactions, and are potential sources of cytoplasmic diversity for sunflower breeding. 相似文献
17.
Summary If M. aquatica (2n=96) having the genotype cc AA ff RR, 60–80% menthofuran, but almost no menthone, menthol, and menthyl acetate is hybridized with M. longifolia (2n=24) having the genotype cc aa FF rr, 4–5% piperitone and 66% piperitone oxide all F1 hybrids have the genotype cc Aa Ff Rr. They also differ from either parent in having about 1.2–5.5% menthone, 4–42% menthol, 2–20% menthyl acetate, and usually only 1–7% menthofuran. However a few individuals may have as much as 41% disomenthone, 6% pulegone, 45% menthofuran or 10% beta-caryophyllene. M. dumetorum, considered by taxonomists to be a natural M. aquatica-M. longifolia F1 hybrid, has the same 14 oil constituents observed in the experimentally produced hybrids. Thirteen of the oil constituents of the single M. dumetorum strain are within the quantitative range of 9 highly variable hybrids. The 17% pulegone of the natural strain was higher than the 6% observed in the hybrids. The M. aquatica-M. longifolia F1 hybrids have the same major oil constituents as M. piperita but in very different quantitative proportions. Since the sporophytic chromosome number of M. dumetorum has been reported as 72, 84, or 96, the suggestion is made that some strains are secondary hybrids from backcrossing and that others with 72 chromosomes may be F1 hybrids between M. aquatica and piperitone strains of M. spicata or M. crispa. Hybrids with polyploid M. longifolia are not greatly different in oil composition. 相似文献
18.
J. B. O. Owuor 《Euphytica》1985,34(2):355-360
Summary Melosis was studied in Coffea arabica, in induced tetraploid C. canephora, in their F1 hybrid (arabusta hybrid) and in backcross generations of the hybrid with C. arabica as recurrent parent. Irregularities were observed, consisting of univalents (especially in the arabusta hybrid), multivalents (especially in tetraploid C. canephora) and uneven distribution of chromosomes at first anaphase. Chromosome distribution was improved by backcrossing. Meiotic irregularities wer negatively correlated with pollen fertility. 相似文献
19.
2n Gamete formation in the genus Brachiaria (Poaceae: Paniceae) 总被引：1，自引：0，他引：1
Patrícia Helena Gallo Pamela Lonardoni Micheletti Kellen Regina Boldrini Claudicéia Risso-Pascotto Maria Suely Pagliarini Cacilda Borges do Valle 《Euphytica》2007,154(1-2):255-260
Microsporogenesis of several Brachiaria species of the Brazilian collection at Embrapa Beef Cattle has been analyzed in detail. This paper reports abnormal cytokinesis
in three accessions of three different species (Brachiaria humidicola, 2n = 4x = 36, Brachiaria decumbens, 2n = 4x = 36, and Brachiaria dura, 2n = 6x = 54). Chromosomes paired in bi-, tri-, and quadrivalents in these accessions, whereas chromosome segregation at meiosis
I was characterized by exclusion of laggards as micronuclei. In a high number of meiocytes, the first sign of cytokinesis
appeared only in metaphase II and did not divide the meiocyte into a dyad. Total absence of cytokinesis was also detected
among meiocytes in the second division. Since in both cases the two metaphase plates were very close, they favored the rejoining
of chromosome sets after anaphase II and formed a restitutional nucleus in telophase II. Second cytokinesis occurred after
telophase II in most meiocytes. Monads, dyads, and triads with n or 2n nuclei were observed among meiotic products. The 2n gametes observed correspond to the first division restitution (FDR). The number of affected cells in each accession was variable,
but the number of microspores with restitutional nucleus, including those scored in tetrads and the released ones, did not
exceed 9%. Although polyploidy is common in the genus Brachiaria, its origin is still unclear. Current results suggest that 2n gametes may have contributed to the evolutionary history of the genus. 相似文献
20.
Summary Five parents from each of four race groups of common bean (Phaseolus vulgaris L.) were hybridized to produce five crosses within each group. Also, five crosses were made for each of the six possible combinations among four groups. Parents, F1 and F2, and parents, F2 and F3 were evaluated for seed yield in 1990 and 1991, respecitively, at two locations in Colombia.Yield of parents belonging to Middle American races and crosses among them was higher than that of races of Andean origin. Positive correlations were found among the mid-parent value, F1, F2 and F3. Also, the mid-parent value predicted the mean seed yield of all possible lines that could be derived from the F-generation in 42 out of 47 crosses. Four crosses, all between common bean races of Andean and Middle American origin, indicated a possible loss of favorable epistatic parental alleles. On average, mean yield of interracial F1 hybrids was higher than that of intraracial ones.Positive heteroris (26.4%–123.8%) over the mid-parent in 31 crosses, and F1s yielding higher (23.7%–91.8%) than the high parent in 20 crosses and yielding higher (22.1%–53.2%) than the highest control among all parents (MAM 13) in 12 crosses, were found. Heritability, estimated by the parent-offspring regression, ranged from 0.42± 0.07 to 0.49±0.04. Expected and realized gains from selection (at 20% selection pressure) ranged from 10.3% to 21.0% over the mean of F1 hybrids and F2 and F3 population bulks. 相似文献