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1.
A total of 45 tetraploid-diploid (4x—2x) hybrid progenies were obtained by crossing each of ten diploid parents as males to each of five tetraploid parents. Means of six traits of the 45 progenies obtained from a two-year experiment were used in progeny analysis. A new mathematical model is developed for analyzing the incomplete two-way table. It is modified from the conventional model for factorial mating design. The aim of the model is to evaluate the potential of 2x parents in terms of their mean effects (μi) and sensitivity measures (Bi) to the 4x parents. The 4x parents were treated as testers in the model. They were compared by the estimates of the magnitude of tester effects (gi). The mean effects of 2x parents showed a dominant influence on variation of tuber number and mean tuber weight of the hybrid progenies. They also demonstrated a substantial influence on the variation of total and marketable yield, chipping score and specific gravity. The linear response of 2x parents to 4x parents, however, also showed a substantial influence on the variation of the latter traits. The information on μi and Bi are useful in terms of choosing superior 2x parents and, together with gj of 4x parents, 4x—2x progenies for specific traits. The μi and Bi estimates of the six traits showed a complicated interrelationship to each other. 相似文献
2.
利用能产生2n配子的二倍体杂种与四倍体普通栽培种(S.tuberosum L.)和四倍体新型栽培种(Neo—tuberosum)进行了2x-2x,4x-2x和2x-4x间的杂交,获得了18个杂交组合的4x杂种家系,将这些家系与其10个4x亲本品种(品系)及对照品种在同一地点进行了连续两年的比较试验。结果表明:4x杂种家系单株平均块茎产量比亲本两年分别高16％和19％;其中最好的6个杂种家系比较好的4个品种(品系)分别高20％和43％;杂种产量的优势主要表现在单株块茎数目的显著增多,但在块茎商品率方面则与4x亲本差异不显著,而且杂种块茎的表现还不如4x亲本及对照品种,这是由于具2n配子特性的2x亲本这些性状较差所致。试验结果还表明杂种的遗传背景愈复杂其杂种优势也愈强,进一步说明马铃薯的产量与遗传异质性(多样性)的强弱可能有明显关系,利用2n配子特性可获得较高的遗传异质性。 相似文献
3.
Summary A factorial mating design with six 4x cultivars as stylar parents mated to three groups of pollen parents (4x cultivars, 4x high protein selections, and 2x S. phureja) was used to study breeding behavior of yield, tuber set, marketable yield and hollow heart in potatoes. Mean yield for the 4x-2x hybrids was equivalent to that of their cultivar parents although yield components, tuber set and average tuber size, were greater and less, respectively, than the cultivar parents. High estimates of general combining ability were found in both pollen and stylar parents for yield, tuber set, marketable yield, number of marketable tubers and hollow heart in all three hybrid populations. Specific combining ability estimates were significant only for yield and hollow heart. Frequency of white-fleshed 4x-2x progeny of five heterozygous yellow-fleshed 2x phureja genotypes was used to confirm cytological identification of a first division restitution mechanism operative in the 2x parents. Although three of these phureja genotypes generated high-yielding progeny, two others produced 4x-2x progeny with mean yield similar to that of hybrids among 4x cultivars.Scientific journal series article 11,601 of the Minnesota Agricultural Experiment Station. 相似文献
4.
Summary High level of heterozygosity is directly related to heterosis for yield in polysomic polyploids. Modern breeding schemes in potato (2n=4×=48) involve utilization of wild or cultivated 2 x relatives that provide a source of allelic diversity, and 2n gametes that transfer diversity to the 4 x level. Different levels of allelic diversity and different modes of 2 n egg formation were considered theoretically to determine their significance for the recovery of heterotic 4 x progeny from 2××4× crosses. The support from the experimental data is provided.Decline in parental allelic diversity in 2××4× crosses or 4××4× crosses resulted in significant yield reduction. The average level of homozygosity and loss of intra-locus interactions are equally adequate to predict the trend in yield changes in 4 x potatoes derived from parents of variable allelic diversity utilizing different modes of 2 n egg formation.The differences between the modes of 2 n gamete formation increase when the genetic diversity decreases. The more genetically diverse parents the less pronounced differences between 2 n gametes. Breeding of 4 x cultivars for polygenic traits where nonadditive effects are important should be oriented towards maximizing heterozygosity in terms of allelic diversity. Utilization of 2 n gametes to generate 4 x progeny following 2×–× or 2×–2× crosses upgrades the level of heterozygosity depending on diversity present in parents. 相似文献
5.
Heterosis in yield, endotoxin expression and some physiological parameters in Bt transgenic cotton 总被引：4，自引：0，他引：4
Although heterosis in cotton has been studied for many decades, very little is known about the performance of hybrids derived from Bt transgenic cotton parents. In order to known better the heterosis performance, yield and endotoxin expression in 20 hybrids (F1) and their Bt transgenic parents were examined from 2002 to 2003 (Experiment 1), and the dynamics of source, sink and their ratios in a well‐performing hybrid H01 were investigated in 2004 and 2005 (Experiment 2). Results in Experiment 1 showed an average mid‐parent heterosis of 21.3% and an over check heterosis of 7.6% in lint yield. Considerable heterosis was also detected in boll numbers, boll size and Bt protein content. Of the 20 hybrids, H01 (K0215 × K643) exhibited the greatest heterosis in yield and Bt protein content in 2002 and 2003, while lint yields of H01 were increased 12.6% and 9.1% in 2004, and 11.7% and 8.9% in 2005, compared with K0215 and K643 in Experiment 2, respectively. Significant heterosis for dry matter accumulation and dry matter allocation to reproductive organs and ratio of fruiting forms/total plant (w/w) were also detected in H01. Sources (leaf area, leaf area index, leaf dry weight per plant and diurnal performance of photosynthesis), sinks (number of fruiting nodes, fruiting forms and dry weight of fruiting forms per plant) and the flow from source to sink were significantly enhanced in H01 relative to its parents. Both total N and Bt protein in H01 were higher than those in its parents. Significant correlation was also found between total N and Bt protein in the main‐stem leaves (R2 = 0.877**). It is concluded that there existed considerable heterosis in yield, yield components and endotoxin expression in some Bt transgenic hybrids. Yield advantage of hybrid cotton (F1) over parents can be attributed to improved source, sink and flow, while the enforced expression of Bt genes in hybrid cotton appeared to be due to the enhanced nitrogen level in plants. 相似文献
6.
This is the first report on the production of numerically unreduced (2n) gametes in Actinidia species. Their occurrence was
apparent from direct observations of microporogenesis in 2x, 3x, 4x and 6x plants and was inferred from ploidy analysis of
progenies from 4x-2x and 2x-4x crosses. Both male and female plants were found to produce 2n gametes. 2n gamete producers
were detected only in interploidy crosses. The observed frequency of 2n gametes was either similar to or towards the lower
end of the ranges reported for other genera. The role of sexual polyploidization in the evolution of the genus is discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Genetic analysis of rapeseed self-incompatibility lines reveals significant heterosis of different patterns for yield and oil content traits 总被引：7，自引：0，他引：7
Self‐incompatibility is one of the most effective approaches to utilizing heterosis in oilseed rape around the world. To evaluate the heterosis of double low self‐incompatibility, the possibility of combining seed yield and oil content, and the genetic effects of parents on their hybrid progenies, a 2‐year field trial using a 3 × 22 NC II mating design was conducted during the 1999‐2001 growing seasons in Wuhan, China. Significant differences in seed yield per plant and seed oil content were observed among the F1 hybrids and between F1 progenies and their parents. However, the heterosis for seed yield per plant was much greater than that for seed oil content. Mid‐parent heterosis and high‐parent heterosis of seed yield per plant ranged from 5.50 to 64.11% and from –2.81 to 46.02%, while those of seed oil content ranged from –1.55 to 7.44% and –3.61 to 6.55%, respectively. Non‐additive genetic effects were a major mechanism that accounted for the yield heterosis in addition to additive effects. In contrast, seed oil content heterosis was mainly dependent on an additive genetic effect. General combining ability (GCA) determined the stability of hybrid cultivars. In hybrid breeding, parental materials might be selected by the sum of GCAs and variances of special combining abilities (SCAs) of female and male parents for traits affected by both additive and non‐additive effects, and by the sum of GCAs of two parents for traits controlled mainly by additive effects. Primary branches and their siliques were the most important yield traits. 相似文献
8.
Heterosis in hybrid wheat varieties produced using a chemical hybridising agent was assessed in field experiments. Hyno Esta and its parents were compared in factorial combinations of four-seed rates (25–300 seeds m–2) and two nitrogen fertilizer rates (0 and 200 kg N ha–1) in 2001/02 and again in 2002/03. Hyno Rista and Hyno Renta and their parents were compared at two-seed rates in 2001/02. Hyno Rista and its parents were added factorially to the Hyno Esta experiment in 2002/03, while Hyno Renta and Hybred and their parents were compared at two seed rates in 2002/03. Mid parent heterosis for grain yield was found in three hybrids and two of these showed high parent heterosis. High parent heterosis in Hyno Esta over a range of sowing densities was mostly exhibited in total biomass but also, in one of two years, in harvest index. High parent heterosis in Hyno Renta was associated more with harvest index than with biomass. The heterosis for biomass in Hyno Esta resulted from greater interception of photosynthetically active radiation (PAR) than the male parent, with better radiation use efficiency than the female parent. In both seasons Hyno Esta achieved grain numbers per ear at least as high as the high parent for this trait (Audace), and combined this with mean grain weights at least as heavy as the high parent for mean grain weight (Estica). Much of the increased biomass and grain yield in the hybrid came late in the season as high parent heterosis was expressed for both maximum grain filling rate and grain filling duration. Heterosis was higher when nitrogen was applied than when withheld; only greater at lower seed rates when expressed in proportionate terms (e.g. as a percentage of the parents), rather than in absolute terms (e.g. t ha–1); and greater in the year with the cooler and wetter summer. 相似文献
9.
The relative value of haploid Tuberosum-Solanum chacoense (TCH) vs. Solanum phureja-haploid Tuberosum (PTH) hybrids as male parents in 4x–2x crosses was estimated under two distinct crop management systems.
The first experiment (E#1) was carried out with supplementary irrigation (three times a week) at Hancock-Wisconsin (WI) with
27 families derived from a sub-set of crosses involving 11 tetraploid (4x) cultivars and 10 diploid (2x) clones (3 TCH; 6
PTH; and one TCH-PTH hybrid clone). A second experiment (E#2) was conducted at Rhinelander-WI with the same group of families
but it was only rainfed with no supplementary irrigation being provided during the entire course of the assay. For comparison,
a complete set of 4x and 2x clones (used as parents) was also planted in each location. Three traits were evaluated in both
locations: total tuber yield (TTY), haulm maturity (HM), and plant vigor (PV). Altogether, 18 out of 27 and 10 out of 27 families
outyielded the corresponding 4x parents at E#1 and E#2, respectively. Significant differences among all 4x–2x families and
among families of the TCH group were observed for TTY at both locations. No difference was found for TTY among families of
PTH and [TCH–PTH] groups at each location. A total of 75% and 50% of the TCH families outyielded their 4x parents at E#1 and
E#2, respectively. The percentage of families from the PTH group that outyielded their 4x parents at E#1 and E#2 was 83.3%
and 25%, respectively. The TCH group had on average lower HM scores than PTH (at both locations) indicating some segregation
for earliness. However, the HM values of the 4x–2x families were, in general, higher than those observed for the 4x parents.
For PV, the PTH group mean was significantly higher than TCH group only in E#1. The PV values of the 4x–2x families were higher
than the 4x-parent group at both locations. Our results indicated that TCH hybrids might be as good parents as PTH to increase
the TTY of 4x–2x progenies. In addition, the TCH families displayed a slight higher level of performance under more stressful
growing conditions than PTH hybrids as indicated by the assay at Rhinelander. Therefore, selection of genetic materials with
potential broad range of adaptation seems to be feasible with both hybrids via the 4x–2x breeding scheme.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Summary The effect of self-pollination of cucumber (Cucumis sativus L.) for 6 generations in lines developed from the North Carolina Medium Base Pickle population was determined by regression of trait expression for each generation on Wright's coefficient of inbreeding. Two yield traits (total and marketable), earliness and 3 fruit quality traits (shape, color and seedcell size) were evaluated in 2 environments (spring and summer, 1983). The regression did not result in significant negative slopes, indicating that inbreeding depression was not important in the population for the traits studied. Midparent heterosis was found for most traits in many hybrids obtained from crossing S6 lines with the gynoecious inbred line, Gy 14A. 相似文献
11.
Agronomic and qualitative characteristics of ten bread wheat hybrids produced using a chemical hybridizing agent 总被引：5，自引：0，他引：5
Summary Ten experimental hybrids derived from the crossing of representative Italian pure-line varieties were grown at three locations in 1984–85. The amount of F1 seed produced from the crossings ranged from 1.5 up to 4 kg per plot of 20 m2. Hybrid purity was on average 88% when estimated through the growout test and 82% when estimated through acid polyacrylamide gel electrophoresis (A-PAGE) of gliadin.All the hybrids showed high-parent heterosis for plant height. Grain yield was higher in the hybrids (71.1 q/ha) than in the female parents (66.5 q/ha); the range of mid-parent heterosis being-10% to +17%. Four hybrids showed standard heterosis (yield advantage). The highest value (+6%) was obtained with the combinations Chiarano x Leopardo and Claudia x Leopardo. Among yield components, the number of spikelets/spike proved to be an important trait and may explain the superiority of the hybrids over the traditional varieties.The bread-making quality appeared intermediate to that of the parents or closer to that of the poorest parental variety. 相似文献
12.
Akshay K. Pradhan Yaspal S. Sodhi Arundhati Mukhopadhyay Deepak Pental 《Euphytica》1993,69(3):219-229
Summary Divergence of 25 accessions of Brassica juncea of Indian, CIS (Commonwealth of Independent States, former USSR) and synthetic origin was studied by D2 analysis. On the basis of divergence, ten accessions were selected and crossed in a diallel fashion without reciprocals to study the combining ability and heterosis. None of the accessions was found to be a good general combiner for all the nine quantitative characters that were studied. Significant heterosis over better parent for single plant yield was recorded in CIS x Indian and synthetic x CIS crosses (5 each) followed by Indian x synthetic types (3). The analysis of component characters showed that the mean performance of the majority of hybrids was intermediate for five out of six yield attributing traits, thus exhibiting dominance or partial dominance effect. To estimate the contribution of such yield attributing traits towards heterosis for yield, a comparison was made among three parameters viz. heterosis over mid parent (MP), better parent (BP) and better yielding parent (BYP) of the concerned hybrid. It was observed that estimation of heterosis from BYP was a more accurate method to determine the contribution of component characters towards yield heterosis than the analysis based on MP and BP. From the component character analysis, it was concluded that characters like number of primary and secondary branches, number of siliqua per plant and siliqua density contributed significantly towards heterosis in yield. Plot level yield trials of two selected hybrids (Skorospieka II x RH30 and Donskaja IV x Varuna) over two growing seasons revealed 29.4 to 91.8% heterosis over BYP. 相似文献
13.
棉花杂种优势与几种生理生化指标的相关性 总被引：12，自引：0，他引：12
对８个陆地棉杂种及其亲本的四种生理生化指标进行了测定，并研究了这些指标与杂种产量优势的相关性，结果表明：幼芽匀浆互补法对Ｆ１皮棉超亲优势、中亲优势的预测相符率分别为８７．５％和７５．０％；杂种萌动种子ＡＴＰ含量普遍高于双亲平均值。超亲优势、中亲优势与杂种ＡＴＰ含量及双亲ＡＴＰ含量的平均值均呈正相关，且中亲优势与杂种ＡＴＰ含量相关显著（ｒ＝０．７１８８，Ｐ〈０．０５）；杂种产量优势与盛蕾期、盛花期的 相似文献
14.
15.
Genetic diversity between parents is important for hybrid breeding and for maximum usefulness of a cross in pure line breeding. However, wide crosses may suffer from poor adaptation in the target environments and recombination losses owing to disruption of favourable epistatic gene combinations. In this study we investigated the importance of various gene effects for different traits in the parents and generations F1 to F5 derived from 99 intra- and inter-pool crosses among 20 lines of the Minor, Major, and Mediterranean germplasm pools of faba bean in Mediterranean and German environments. Yield performance of parental inbreds and progenies of crosses in different selfing generations was high in the region of adaptation of the respective germplasm pool. Heterosis for yield was greatest in interpool crosses of Minor × Mediterranean germplasm, amounting to 106% in Mediterranean and 72% in German environments. Interpool crosses exhibited significantly greater heterosis compared with intrapool crosses in both mega-environments. Generation means analysis revealed the importance of additive gene effects and dominance × dominance epistasis in Mediterranean and German environments. Dominance effects and additive × additive epistasis for yield were negligible in most crossing groups. Since intrapool crosses of Mediterranean germplasm in Mediterranean environments and crosses of Minor and Major germplasm in the German environments were most promising, we suggest crosses among adapted germplasm for hybrid breeding and for establishing new base material in line breeding in faba bean. 相似文献
16.
试验于1987～1989年在乌兹别克共和国实验生物研究所和塔什干农学院进行。研究结果表明,用矮秆、早熟陆地棉和海岛棉杂交,F_1的营养生长优势弱,而生殖优势强。集约化类型陆地棉和海岛棉杂交种的叶面积小,叶绿体数量少,而单叶绿体的光合作用强度和光化学活性增强,杂交种可以很经济地利用细胞资源。试验结果还显示,陆地棉、海岛棉栽培种与野生、半野生亚种的杂交后代表现出明显的核质基因互作效应。当野生、半野生棉为母本时,后代的主茎高度,果枝长度,叶面积和根系发育受到抑制。 相似文献
17.
18.
Summary Seven Solanum tuberosum ssp. tuberosum and three Solanum tuberosum ssp. andigena accessions were crossed to produce 12 Tuberosum × Tuberosum (T × T) and 9 Tuberosum × Andigena (T × A) progenies. These families were evaluated for five important traits for two successive clonal generations under short day sub-tropical plains. The differences in yield, average tuber weight and tuber number between {T × T }and T × A families in an early (75 days) crop were not significant. Compared to conventional intra-Tuberosum families, T × A families had significantly higher % tuber dry matter and specific gravity. In contrast to intra-Tuberosum crosses, T × A crosses exhibited a positive heterosis for tuber yield. Compared to T × T families, T × A families showed significantly higher heterosis for yield and tuber number. Comparison of T × T and T × A families and parents using canonical analysis led to the identification of superior hybrid families and superior parents. Some T × A progenies were close to breeding goal and thus can be used for selecting high-yielding cultivars. This revealed the usefulness of Andigena genotypes as parents in developing early bulking potato cultivars with broad genetic base for short day sub-tropical plains. 相似文献
19.
Comparison of two crossing and four selection schemes for yield, yield traits, and slow rusting resistance to leaf rust in wheat 总被引：5，自引：0，他引：5
The most important breeding objectives in crop improvement are improving grain yield, grain quality, and resistances to various
biotic and abiotic stresses. The objectives of our study were to compare two crossing and four selection schemes for grain
yield, yield traits, and slow rusting resistance to leaf rust (Puccinia recondita) based on additive genes in wheat (Triticum
aestivum), and to identify the most efficient crossing and selection methodologies in terms of genetic gains and cost efficiency.
Segregating populations were derived from 18 simple crosses and the same number of top (three-way) crosses. Half of the crosses
were derived from Yecora 70 and the other half from Veery #10 as the common leaf rust susceptible parents. The four selection
schemes were: pedigree, modified bulk (F2 and F1-top as pedigree, selected lines in F3, F4, F2-top, F3-top as bulk; and pedigree in F5 and F4-top populations), selected bulk (selected plants in F2, F3, F4, F1-top, F2-top and F3-top as bulk; and pedigree in F5 and F4-top populations), and nonselected bulk (bulk in F2, F3, F4, F1-top, F2-top and F3-top; and pedigree in F5 and F4-top populations). A total of 320 progeny lines, parents and checks were tested for grain yield, other agronomic traits and
leaf rust resistance during the 1992/93 and 1993/94 seasons in Ciudad Obregon (Sonora State, Mexico) which represents a typical
high yielding irrigated site. The influence of the type of cross and the selection scheme on the mean grain yield and other
traits of the progenies was minimal. The selection of parents was the most important feature in imparting yield potential
and other favourable agronomic traits. Moreover, the highest yielding lines were distributed equally. Progeny lines derived
from Veery #10 crosses had significantly higher mean grain yield compared to those derived from the Yecora 70 crosses. Furthermore,
a large proportion of the highest yielding lines also originated from Veery #10 crosses. Mean leaf rust severity of the top
cross progenies was lower than that of the simple cross progenies possibly because two parents contributed resistance to top
cross progenies. Mean leaf rust severity of the nonselected bulk derivatives was twice that of lines derived from the other
three schemes. Selected bulk appears to be the most attractive selection scheme in terms of genetic gains and cost efficiency.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
Transmission of resistance to common scab from the diploid to the tetraploid level via 4x-2x crosses in potatoes 总被引：1，自引：0，他引：1
Summary Diploid potato clones selected for their reaction to common scab and their ability to produce 2n male gametes were used in a series of crosses to a susceptible tetraploid female parent (cv. Shepody). In addition, two tetraploid clones were also selected for their reaction to common scab and crossed with Shepody as a female parent. Results indicated that resistance to common scab can be effectively transmitted from the diploid to the tetraploid level via 4x-2x crosses. Diploid parents producing 2n pollen via either first division or second division restitution can be used to transmit scab resistance. A relatively small proportion of resistant individuals could be recovered from susceptible x susceptible crosses in both 4x-2x and 4x-4x combinations. The data support a previously developed hypothesis that scab resistance is relatively simply inherited. 相似文献