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71.
Summary Cauliflowers representing those maturing in Britain in autumn, winter and spring were assessed for self-compatibility by self-pollen tube growth. A tendency existed for groups taking longer to mature to be more self-incompatible, but a range of incompatibilities was apparent in all groups. These results complement those of other workers.It is argued that despite demonstrable heterosis within many groups of cauliflowers, radical advances are probably best made by selecting self-compatible material from annual × biennial hybrid populations. 相似文献
72.
Genetics of grains per spike in durum wheat under normal and late planting conditions 总被引:1,自引:0,他引:1
Parental, F1, F2, BC1, BC2, BC11, BC12, BC21, BC22, BC1 self and BC2 selfed generations of three crosses involving six cultivars of durum wheat (Triticum durum Desf.) were studied for grains per spike under normal and late sown environments to analyze the nature of gene effects. A 10-parameter model did not fully account for the differences among the generation means. In two cases more complex interactions or linkage were involved in the inheritance of grains per spike in durum. Both digenic and trigenic epistatic interactions had a role in controlling the inheritance of grains per spike, however, trigenic interactions contributed more than digenic interactions. Non-fixable gene effects were many times higher than fixable ones in all three crosses and in both sowing environments indicating a major role of non-additive gene effects in the inheritance of this trait. Duplicate epistasis between sets of three genes under both environments was recorded for the cross Raj 911 × DWL 5002. Epistatic interactions, particularly the trigenic ones, contributed the maximum significant heterosis. Epistatic interactions involving dominance in the F2 generations caused significant inbreeding depression. Selective diallel mating and/or biparental mating could be used for amelioration of grains per spike in durum wheat. 相似文献
73.
The female line 1709, carrying the recessivecharacter green cotyledon, marker of the embryogenotype, was cross-pollinated by bees in the presenceof either male line HG115 or male line Dial63. In thecomparison of seeds which resulted either fromintercrossing or from selfing, a xenia effect wasobserved on volume and number of cotyledon cells andon individual seed weight which was dependent on themale line. The increase of hybrid seed weight inducedby the small-seeded male line Dial63 was larger thanthe one induced by the large-seeded male line HG115.The xenia effect on seed weight was correlated withthe level of heterosis in the F1 plant's growth. 相似文献
74.
棉花雄性不育研究和应用进展 总被引:7,自引:4,他引:7
综述了棉花雄性不育类型、不育机理和雄性不育系杂种优势利用状况,着重讨论了棉花雄性不育的细胞学、生理生化和分子生物学研究进展。并对本领域研究和应用中存在的问题及发展前景提出了看法。 相似文献
75.
Studies on "Three Line" Polima Cytoplasmic Male Sterility Developed in Brassica napus L. 总被引:1,自引:0,他引:1
Polima CMS lines can be divided into three groups according to the sensitivity of male sterility to temperature: 1) high temperature CMS lines (62.9%), 2) low temperature CMS lines (28.6 %) and 3) stable CMS lines (8.5 %). The heterosis of Pol CMS hybrids is evident and common in some of the characters tested, especially in plant seed yield and siliqua number. The cytoplasm has no deleterious effects on the FI characters tested. 相似文献
76.
Effects of cytoplasm on heterosis and combining ability for agronomic traits in rice (Oryza sativa L.) 总被引:1,自引:0,他引:1
Summary Effect of sterilizing (WA) cytoplasm on heterosis and combining ability for days to flowering, plant height and grain yield in rice was studied in 70 crosses and their reciprocals produced by 10 cytoplasmic male sterile (A), their maintainer (B) and seven restorer (R) lines following line x tester design. The materials consisting of 140 hybrids (70 A/R and their reciprocal 70 R/B) plus 17 parental lines (10 B + 7 R) were evaluated under six environments, created by growing in three fields with different fertilizer doses (0, 60, 120 kg N/ha) and 2 seasons (dry and wet) during 1986 at IRRI farm. Reciprocal cross effect (A/R vs R/B) were highly significant for all the three traits. Interaction of reciprocal cross effects with environments were also highly significant for yield and days to flowering. Cytoplasmic effect for yield, days to flowering and plant height were estimated by comparing A/R and R/B combination and testing the significance of difference with LSD value. In order to avoid confounding effect of spikelet sterility on yields, twenty crosses showing normal spikelet fertility were selected. Both positive and negative cytoplasmic effects were observed for the three traits. The effects were modified by environments, except for plant height. Heterosis for all three traits was also affected by cytoplasm, however, manifestation of cytoplasmic effects was higher for heterosis for days to flower than in heterosis for yield and plant height. Effect of cytoplasm was more pronounced on general combining ability effects of parents than specific combining ability effects of crosses. Among the parents two CMS lines A4 (IR54752A) and A8 (IR22107-113-3-3A) and two R lines: R2 (IR46) and R7 (IR9761-19-1) showed consistent positive effect of cytoplasm on general combining ability. These lines have given several good heterotic combinations. The study indicated the usefulness of evaluating diverse cytoplasmic sources in various nuclear genotypes bred for hybrid rice breeding program. 相似文献
77.
Twelve primary hexaploid triticale (X Triticosecale Wittmack), synthesized from, three lines of tetraploid wheat (Triticum durum L., T. turgidum L.) and four inbred lines of rye (Secale cereale L.), were used to produce 18 crosses with homozygous wheat and heterozygous rye genome and 12 crosses with heterozygous wheat and homozygous rye genome. Parents and crosses of triticale, wheat, and rye were tested for two years (rye for one year only) in two-replicate block designs with 1 m2-plots. Data were assessed for plant height, grain yield and for yield-related traits. Performance of triticale crosses was considerably lower than that of the wheat and rye crosses. The amount of heterosis varied greatly between years. Positive and mainly significant heterosis was revealed in triticale generations F1 and F2. The average values were closer to those in wheat than to those in rye. For most characters a high level of heterosis was retained in tnucalt1 generation F2. Heterozygosity of the wheat and rye genome both contributed to heterosis in triticale. However, gene action of the rye genome strongly depended on the homozygous wheat background: one wheat line almost completely suppressed and another greatly stimulated the heterotic effect of the rye genome. In the later case, the amount of heterosis was related to that in rye per se. Information from hybrid rye breeding may therefore be used when establishing gene pools for hybrid breeding in triticale. 相似文献
78.
F. L. Stoddard 《Plant Breeding》1986,97(3):210-221
When the flowers are not disturbed, the yield of F1 hybrids of faba beans normally exceeds that in their inbred parents. The basis of this “heterotic autofertility” was investigated by examining flowers for pollination and fertilization throughout the flowering season and assessing the distribution of seeds and pods on mature plants. Six inbred lines and seven of their F1 hybrids were grown without protection from bee visitation, and their autofertility was estimated’ by comparing their fertilization with that of cytoplasmic male-sterile line. The first direct evidence was obtained that heterotic autofertility acts by increasing; the proportion of flowers which were pollinated and fertilized. The autofertility was not perfect, especially in a closed-flower hybrid, as many ovules remained unfertilized. Several factors contributed to the number of seeds per pod in F1 hybrids, being superior to parental means: (1) more ovules per flower, (2) greater fertilization of the basal ovules, (3) reduced abortion of the apical ovules and (4) greater overall maturation ovules. 相似文献
79.
A dwarf mutant ‘NDF‐1′, approximately 70 cm high, was derived from a 200‐cm high doubled haploid (DH) line ‘3529’ (Brassica napus), seeds of which were jointly treated with chemical inducers and bombardment of fast neutron. The leaves of the ‘NDF‐1’ mutant were wrinkled and thicker compared with the wild‐type control. The mutant had much lower values than its original parents for all agronomic traits, except for its seed weight. A genetic analysis revealed that dwarfism is under the control of a major gene (designated as ndf1) with a mainly additive effect and non‐significant dominance effect. Because of the high level of resistance to lodging, breeding programmes for double low dwarf oilseed rape and heterosis utilization were initiated. Some new dwarf strains with improved agronomic performance were developed. The hybrid of the cross between the tall parent and the dwarf line showed increased harvest index and significantly higher seed yield than the tall parent or the control variety ‘Zhongyou 821’ and presented an estimated heterosis vigour rate as high as 12.5–25.8%. The dwarf trait will be a promising marker for a simple, economic and efficient way to control the purity of F1 hybrid varieties in hybrid production of B. napus. 相似文献
80.
Weijun Xu Sant S. Virmani Jose. E. Hernandez Leocadio S. Sebastian Edilberto D. Redoña Zhikang Li 《Euphytica》2002,127(1):139-148
Genetic diversity within and between the maintainer (B) and restorer (R) lines used in hybrid breeding programs of the Philippine
was investigated with information from analysis of pedigree record, quantitative traits and SSR assays. Mean coefficients
of coancestry were calculated as 0.11 within R lines, 0.27 within B lines, and 0.04 between R and B lines, indicating greater
diversity among R lines than among B lines, and the significant divergence between B and R lines. These results are consistent
with those obtained from quantitative trait analysis and SSR marker assays. Relative gene diversity for 37 random SSR markers
averaged 0.20 within B lines,0.28 within R lines, and 0.52 between two groups of lines. There were no consistent associations
among various genetic diversity measures. Random sets of SSR marker and pedigree based diversity measures had no significant
correlation with mid-parent heterosis for grain yield and biomass, indicating that prediction of heterosis for complex traits
based on these two genetic diversity estimates is difficult.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献