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1.
Verticillium wilt (VW) of potato, caused primarily by the fungus Verticillium dahliae, results in yield loss and is therefore an important soil-borne disease. Resistance to VW exists in potato germplasm and is
used by breeders during cultivar development. Breeders could make more rapid progress toward the development of VW resistant
clones if they had an effective early generation selection strategy. The purpose of this study was to determine whether selection
for VW resistance could be carried out in the first tuber generation on single hills. One hundred and fifty-two clones from
19 families were planted as single hills on a V. dahliae-infested field. Each plant was scored for vine maturity, VW symptom expression, yield, stem colonization (colony forming
units (cfu), in dried basal stem segments) and incidence (percent infected stems). In the second clonal generation, which
consisted of replicated four-hill plots, stem colonization scores and incidence values were used to identify clones which
were more resistant than a moderately resistant cultivar and others which were more susceptible than a susceptible cultivar.
The efficiency and reliability of the single-hill selection strategy, based on symptoms and yield, was then determined by
comparison to the four-hill results. We determined that the best single-hill selection strategy was negative selection (discard
clones with the lowest performance) with low stringency, based on yield. 相似文献
2.
The pedigree method is often used for developing inbred lines in maize (Zea mays L.). This study was conducted to assess the effectiveness of pedigree selection for improving resistance to Gibberella ear rot in four maize populations. Selection was based on the severity of ear rot symptoms after inoculation with macroconidial suspensions of Fusarium graminearum (Schwabe) into the silk channel (for two populations) and into the developing kernels (for two other populations). Samples of the selfed families (S1 to S5), recovered from remnant seed from the selection programs, were evaluated for disease resistance during three years, using inoculation and evaluation protocols similar to those used during selection. Among-family selection was effective in both of the populations selected after silk inoculation and in one of the populations selected after kernel inoculation. Responses to selection were more evident in later than in earlier generations for both types of inoculation. Changes in the estimated genetic gain over generations were consistent with changes in the variances among families, which tended to increase in early generations and to decrease in later generations. Selection after kernel inoculation seemed to have been more effective than selection after silk inoculation in developing families with more stable resistance. Based on the results obtained here, it seems that responses to family selection could be accelerated without increasing operational costs by increasing selection intensity in later generations and inoculating fewer plants per family. 相似文献
3.
W. Heijbroek 《Euphytica》1977,26(2):257-262
Summary Within Beta vulgaris and B. maritima origins some partial resistance to beet cyst eelworm was found which could be raised to a very limited extent by selection. However after the second backcross to commercial sugar beet varieties and successive selection of the inbreds this resistance was lost. It was demonstrated that in the rootsystem of resistant plants as much nematodes penetrate and develop as in susceptible ones but the ratio between males and females is different. It was therefore quite probable that this resistance is polyfactorial and merely recessive. 相似文献
4.
B. Maris 《Euphytica》1988,37(3):205-224
Summary The main objective was to determine the reliability of selection in early generations of a potato breeding programme. To that end data were recorded in the seedling generation, an early and a late harvested experiment of the first clonal generation and the late harvested second clonal generation on up to 30 genotypes of 55 populations from crosses of three Solanum tuberosum ssp. tuberosum cultivars and seven selected S. tuberosum ssp. andigena clones, adapted to the northern temperate zone. Phenotypic correlations were computed per population in almost all possible combinations within and between characters between and within generations. The mean across 55 comparable correlation coefficients was considered to be the best estimate of the relationship concerned.In all four experiments data were collected on number of tubers, tuber yield and mean tuber weight; in the three experiments of the two clonal generations in addition on date of emergence, number of stems, plant height, haulm type, and general impression of the underground plant parts and in the two late harvested clonal generations on date of maturity and under water weight.The results confirmed that general impression which is largely decisive for the selection in early generations, is a little reliable measure. However, from the magnitude of the mean correlations between experiments within characters it must be concluded that selection for most of these separate characters is hardly more reliable. An exception was date of maturity for which a mean correlation was determined of r=0.78 between the two clonal generations. The second strongest mean correlations, perhaps surprisingly, were for tuber yield, viz. r=0.52 between the seedling generation and the late harvested first as well as the second clonal generation and r=0.63 between the late harvested clonal generations. From the correlations between characters it appeared that for a high tuber yield, besides its components, in particular an early emergence, a large plant height, an attractive haulm type and a late maturity are of importance.The main conclusion is that, as long as not enough seed tubers are available for the layout of statistically sound experiments, a negative instead of a positive selection should be applied to avoid the rejection of most of the valuable genotypes in an early stage. On the basis of the results directives for the application of such a negative selection are given. 相似文献
5.
Summary The genetics of partial resistance of lettuce to Myzus persicae was studied using F1 and F2 generations of two crosses between a susceptible and partially resistant accession (Norden x Batacer and Liba x Norden) and three crosses in which both parents were partially resistant (Batavia la Brillante x Batacer, Batacer x Liba and CGN4741 x Batacer). Partial resistance to M. persicae inherited quantitatively, without important dominance effects. Only in the cross Batacer x Liba were significant departures of the F1 and F2 from the midparent found, which were probably caused by epistatic effects. Reciprocal F1s had similar resistance levels, indicating the absence of cytoplasmic or other maternal effects. Estimates of broad-sense heritability ranged from 0.34 to 0.61. The results indicated that lines with an improved resistance level can be obtained from crosses between partially resistant accessions, preferably by line selection or the application of indirect marker aided selection.Abbreviations PR
partial resistance, partially resistant
- S
susceptibility, susceptible 相似文献
6.
Summary Narrow sense heritabilities of tolerance to NaCl were estimated in seven grass species using seedling root length after three weeks growth in solution culture containing NaCl. Heritability estimates were obtained from i) female parent-progeny regression, and from ii) selection response and selection differential (realized heritability).Estimates from parent-progeny regression; and realized heritability respectively for each species were as follows Lolium perence L. 0.44, 0.39; Dactylis glomerata L. 0.32, 0.24; Agrostis stolonifera L. 0.28, 0.27; A. castellana L. 0.26; 0.31; Holcus lanatus L. 0.19, 0.23; Festuca rubra L. 0.44, 0.36; Pucinnellia distans (L.) Parl. 0.72, 0.77. These data suggest that in all species except perhaps H. lanatus, improvement in seedling NaCl tolerance could be obtained through further selection and breeding. 相似文献
7.
Elaine McElhinny Eduardo Peralta Nelson Mazón Daniel L. Danial Graham Thiele Pim Lindhout 《Euphytica》2007,153(3):373-384
Summary Field trials were carried out in Ecuador with two indigenous communities, Ninín Cachipata and La Esperanza, to determine farmers’
preferences for quinoa (Chenopodium quinoa Willd.) cultivars and to improve PPB processes. More women than men participated, reflecting that quinoa, a primarily subsistence
crop, is mainly managed by women. Farmers’ field selection criteria for quinoa in the field were mostly based on yield, earliness
and plant colour; however only breeders’ measurements of yield and panicle height significantly correlated to farmer selection
scores. Older women gave higher scores than younger women or men, apparently due to a concept of no cultivar being without
value. Working in same gender pairs improved evaluation richness. INIAP technicians were more discriminating in their evaluations
than farmers. They also used additional selection criteria of disease resistance and uniformity. At seed selection, farmers
from Ninín Cachipata, where food security is not assured, chose lines based on yield, while farmers from La Esperanza, where
resources are less limiting, also considered seed size, colour, saponin content and marketability. Field characteristics were
not taken into consideration at seed selection, signifying that farmers are less interested in those characteristics, or that
it was difficult for them to correlate field data when presented in tabular form with seed characteristics. Future trials
with small farmers should have fewer lines or replications to avoid farmer fatigue during evaluation. Farmers who grow primarily
for subsistence in semi-arid environments have more interest in growing quinoa, and more to gain from having improved cultivars;
therefore future participatory efforts should focus on them. 相似文献
8.
Summary For 10 years the method developed by Van der Meer et al, (1970) to test neck rot resistance in onions has been applied in a breeding programme. From experiments with market varieties, inbred lines and half-sib families it is concluded that neck rot resistance as determined by this method is a quantitative character, which shows continuous variation and is in part fixable by selection. The practical importance of this type of neck rot resistance is not yet clear.Report no. 68 相似文献
9.
Summary Scab caused by Gibberella zeae Petch., in common wheat, is one of the most severe diseases in China. A source population C0, bred for scab resistance, was developed through three cycles of multiple-parent crossing and intercrossing by means of the dominant male-sterile gene Ta1 (Ms2), according to Wu's scheme. Phenotypic recurrent selection methods for increasing the resistance to scab-infection of spikelets and seeds with the male-sterile plants were carried out simultaneously in Nanjing and Shanghai and at Jianyang, Fujian Province, for three cycles. The generations from C0 to C3 and two check cultivars were evaluated, using a randomized block design, under conditions of an artificially induced epidemic of scab during 1988–1990. The results indicate that there were significant differences in the resistance to scab between these generations. On average, the percentages of diseased spikelets and seeds of the male-fertile plants were reduced by 9% and 10%, respectively. The frequency of resistant plants was distinctly enhanced by recurrent selection. Analysis of variance showed that no significant differences existed between cycles of recurrent selection in agronomic characters such as plant height, spikes per plant, spike length, numbers of spikelets and seeds per spike, weight of seeds per spike and 100-kernel weight, days to heading and to maturity. Except for plant height, most of these traits tended to be slightly improved with improvement of resistance in the gene pool. The variance for resistance in the generations was decreased under selection. Recurrent selection for scab resistance using the dominant male-sterile gene Ta1 (Ms2) was both an effective and feasible breeding method for producing this character in wheat. 相似文献
10.
Summary The efficiency of indirect selection for seed yield was compared with direct selection for yield per se in chickpea. A total of 2500 single F2 plants, derived from 50 crosses with 50 plants from each cross, were divided into five sub-populations (SP1 to SP5) of 500 plants each by including 10 plants from each of the 50 crosses. The five sub-populations were advanced upto F6 by exercising 10% selection intensity for four successive generations for number of pods per plant in SP1, number of seeds per pod in SP2, seed weight in SP3, seed yield in SP4 and random selection in SP5. The efficiency of direct and indirect selection for yield was evaluated by comparing groups of 50 F6 lines from each sub-population. SP1 and SP3 F6 lines showed higher mean grain yield than the other three methods. SP1 and SP3 were found to be almost equally efficient in developing F6 lines which were significantly superior to the check. This suggests that indirect selection for yield via pod number and seed weight is more efficient than direct selection for yield. 相似文献
11.
Bernard Tivoli Alain Baranger Carmen M. Avila Sabine Banniza Martin Barbetti Weidong Chen Jenny Davidson Kurt Lindeck Mohammed Kharrat Diego Rubiales Mohamed Sadiki Josefina C. Sillero Mark Sweetingham Fred J. Muehlbauer 《Euphytica》2006,147(1-2):223-253
Summary Necrotrophic pathogens of the cool season food legumes (pea, lentil, chickpea, faba bean and lupin) cause wide spread disease
and severe crop losses throughout the world. Environmental conditions play an important role in the development and spread
of these diseases. Form of inoculum, inoculum concentration and physiological plant growth stage all affect the degree of
infection and the amount of crop loss. Measures to control these diseases have relied on identification of resistant germplasm
and development of resistant varieties through screening in the field and in controlled environments. Procedures for screening
and scoring germplasm and breeding lines for resistance have lacked uniformity among the various programs worldwide. However,
this review highlights the most consistent screening and scoring procedures that are simple to use and provide reliable results.
Sources of resistance to the major necrotrophic fungi are summarized for each of the cool season food legumes. Marker-assisted
selection is underway for Ascochyta blight of pea, lentil and chickpea, and Phomopsis blight of lupin. Other measures such
as fungicidal control and cultural control are also reviewed. The emerging genomic information on the model legume, Medicago truncatula, which has various degrees of genetic synteny with the cool season food legumes, has promise for identification of closely
linked markers for resistance genes and possibly for eventual map-based cloning of resistance genes. Durable resistance to
the necrotrophic pathogens is a common goal of cool season food legume breeders. 相似文献
12.
H. Z. Cross 《Euphytica》1985,34(2):409-418
Summary A selection procedure to change the drying rates of maize (Zea mays L.) ears was developed and tested. Results indicated that drying rates were affected by hybrid genotype, ear maturity at harvest, number of kernels per row, ear diameter, and moisture content at harvest.Mass selection was initiated in an early synthetic, NDSG, in an attempt to produce both fast and slow drying strains. After two cycles resultant substrains were evaluated in the laboratory for direct and in the field for correlated selection responses. Laboratory results indicated that selection effectively changed moisture loss rates in NDSG, and confirmed earlier observations that an ear's moisture content at harvest affects its drying rate.Data from field experiments grown at five locations in 1980 revealed that each of two selection cycles for slow laboratory drying rate significantly reduced ear moisture content at harvest, in the field. This lower harvest moisture content appeared to result from a lower moisture content at physiological maturity rather than a faster drying rate. Other correlated selection responses included lowered yield, plant height, and ear weight due to selection for fast laboratory drying, and lowered plant height and ear weight from selection for slow drying.Data indicated that this selection procedure can be used to change moisture loss rate and ear moisture content at harvest. Results also contributed to understanding of factors involved in ear drying rates which may lead to more effective selection procedures.Journal Article No. 1385 of the North Dakota Agri. Exp. Stn., Fargo. 相似文献
13.
The potential of selection and breeding for improved salt tolerance in lucerne (Medicago sativa L.) 总被引：1，自引：0，他引：1
Summary Four cultivars of Medicago sativa L. were subjected to selection for improved salt tolerance using a salinized solution culture technique at 250 mM NaCl. Selections were made after two weeks growth, based upon seedling shoot length differences. High (shoot lengths 14–31 mm) and low (7–12 mm) selection lines were established. Unselected shoot lengths ranged from 0–11 mm. Selection intensities ranged from 0.17% to 0.22% for the high selection lines, and from 0.30% to 1.05% for the low selection lines.Eleven selected plants from cv. CUF 101, and 10 from Local Syria were grown on and polycrossed. A sample of progeny seed from each was grown at 8 NaCl concentrations in solution cultures. Selected line seedlings produced shoots at 225, 250, 260, and 275 mM NaCl, whereas unselected material failed to grow above 225 mM NaCl. A second cycle of selection at 280 mM NaCl with these two cultivars achieved selection intensities of 0.21% and 0.45% for high and low selection lines, respectively. Selected lines grew and produced shoots at 300 mM NaCl.Seedlings derived from 1st and 2nd selection cycles and unselected control material were grown for 6 weeks at 0, 150, 175, and 200 mM NaCl in a sand culture experiment. The high selection line produced significantly greater shoot fresh weight, dry weight, and % live shoot weight than the unselected control material. Clearly selection as practised here can isolate individual seedlings having enhanced genetically based tolerance to NaCl, which is manifest in mature plants derived from polycrossing those selected individuals. 相似文献
14.
Summary Eleven populations of Brassica napus L. and twelve populations of B. campestris L. were subjected to three cycles of selection for fast germination at 2°C and at 25°C. The seeds from the selected populations, and unselected control populations grown in the same environment as the selected populations, were examined for germination behaviour at 2°C and 25°C, and for growth behaviour at 10°C. The populations in both species responded differently in terms of germination behaviour to selection for fast germination. In most of the populations that did respond positively to selection, selection practised at 2°C was superior to selection at 25°C in improving percent germination at 2°C, and was as good as the selection at 25°C in improving germination rate at the higher temperature. Selection for fast germination had no effect on growth characteristics of B. napus and B. campestris populations grown at 10°C. Thus, selection for fast germination at one low temperature may lead to improvement in germination characteristics over a range of temperatures, but will not necessarily lead to improved growth performance of the selected populations. 相似文献
15.
Summary Calli of resistant, intermediary and susceptible wheat (Triticum aestivum L.) varieties were selected using culture filtrates of Fusarium graminearum and F. culmorum and the regenerants were evaluated for resistance up to R3. Czapek-Dox broth medium was inoculated with mycelia of Fusarium isolates and incubated for 2–6 weeks. Filtrates were added to MS callus growing medium, then 5 weeks-old calli were transferred onto this medium (MST) for 4–5 weeks. MST containing 30% filtrate was found to be suitable for selection. Resistant calli were transferred again to fresh MST for further two selection cycles. The surviving calli produced less fertile regenerated lines (R0) than the non-selected ones. Among 18 R1 lines tested for Fusarium-resistance in the seedling stage by artificial inoculation in the greenhouse, two (11.1%) were significantly more resistant, one (5.6%) was more susceptible than the original cultivar and the rest (83.3%) behaved similarly to the donor plants. Among unselected R3 lines of three varieties, practically the same number of resistant plants were found as among the related selected ones. When the R3 selfed generations obtained through double-layer and culture filtrate selection techniques were tested for Fusarium-resistance, 35.7% of the lines were found to be more resistant than the original cultivars, none was more susceptible and 64.3% had a reaction similar to that of the source materials. Thus, inheritance of the disease reaction was not stable in all cases. Success of in vitro selection for Fusarium-resistance depended also on the genotype, and toxin analysis showed that although being effective, the selective media contained deoxynivalenol only exceptionally. In selecting wheat for Fusarium-resistance in vitro, the culture filtrate technique proved better than the double-layer procedure. 相似文献
16.
Haploid selection for traits related to pollen cold tolerance in tomato was performed in segregating populations derived from a Lycopersicon esculentum × L. pennellii hybrid. BC1 populations were obtained by combining normal and low temperature treatments on two stages of pollen development: pollen formation, and germination and pollen tube growth. F1 hybrids were cultivated under low and normal temperatures and their pollen was used to pollinate L. esculentum plants at low and normal temperatures. The four BC1 populations obtained were tested for the quality and quantity of pollen produced at low temperatures. The population obtained by cold treatment at both stages had a significantly improved pollen germination ability at low temperatures. The two other coldselected BC1 populations showed no differences compared with the unselected BC population. A second cycle of pollen selection, corresponding to BC2, was applied in order to test its persistence in the subsequent generations and the possibility to further improve the character. This second cycle showed no improvement although some plants retained the high pollen germination ability at low temperatures that was observed in the first cycle. Hence, gametophytic selection of some characters related with tomato pollen performance may be feasible, at least for the first cycle of selection. 相似文献
17.
Screening techniques and sources of resistance against parasitic weeds in grain legumes 总被引：1，自引：0，他引：1
Diego Rubiales Alejandro Pérez-de-Luque Mónica Fernández-Aparico Josefina C. Sillero Belén Román Mohamed Kharrat Shaban Khalil Daniel M. Joel Charlie Riches 《Euphytica》2006,147(1-2):187-199
Summary A number of parasitic plants have become weeds, posing severe constraints to major crops including grain legumes. Breeding
for resistance is acknowledged as the major component of an integrated control strategy. However, resistance against most
parasitic weeds is difficult to access, scarce, of complex nature and of low heritability, making breeding for resistance
a difficult task. As an exception, resistance against Striga gesnerioides based on a single gene has been identified in cowpea and widely exploited in breeding. In other crops, only moderate to low
levels of incomplete resistance of complex inheritance against Orobanche species has been identified. This has made selection more difficult and has slowed down the breeding process, but the quantitative
resistance resulting from tedious selection procedures has resulted in the release of cultivars with useful levels of incomplete
resistance. Resistance is a multicomponent event, being the result of a battery of escape factors or resistance mechanisms
acting at different levels of the infection process. Understanding these will help to detect existing genetic diversity for
mechanisms that hamper infection. The combination of different resistance mechanisms into a single cultivar will provide durable
resistance in the field. This can be facilitated by the use of in vitro screening methods that allow highly heritable resistance components to be identified, together with adoption of marker-assisted
selection techniques. 相似文献
18.
Summary A assessment of in vitro characters: embryo size, differentiation stage and germination time of haploid embryos, was carried out with a view to developing a selection procedure to increase the efficiency of doubled haploid (DH) production using the Hordeum bulbosum system. The differentiation stage of haploid embryos at the time of excision was found to be the most promising character for selection. In the two spring crosses examined 55% of excised embryos were undifferentiated and 45% were differentiated, with overall success rates, in terms of the percentage of DHs produced, of 7.91% and 25.16%, respectively. 17% of excised embryos produced callus. These embryos performed poorly in terms of regeneration and subsequent growth. It is suggested that only differentiated non-callusing embryos are maintained in order to maximize the efficiency of DH production. It is also shown that the overall success rate depends not only on initial stages such as seed setting but also on genotypic differences in response to colchicine treatment at later stages. 相似文献
19.
Four cycles of recurrent selection for FHB resistance were conducted in an intermating wheat breeding population using the
dominant male-sterile gene ms
2 during 1987–1991.Five cycles of phenotypic mass selection for male-sterile plants were evaluated using the soil-surface inoculation
method in Experiment I. Experiment II evaluated changes in FHB scores during five cycles of progeny selection for fertile
plants using the single-floret inoculation method. In Experiment I, the average level of FHB response increased to MR level
in C4, compared to MS level in C0. The numbers of infected spikelets and diseased kernels decreased 0.32 and 2.68 per cycle, respectively. In Experiment II,
the average level of FHB response increased to R level in C4F1. The numbers of infected spikelets and diseased kernels decreased 0.93 and 4.58 per cycle, respectively. In both experiments,
the largest selection gains were realized in the first cycle. The frequencies of R and MR individuals were increased significantly.
The frequencies of individuals with FHB response equal and/or superior to Sumai 3 were increased to 5–8% in C4 and 25% in C4F1after the fourth cycle. Agronomic traits tended to be slightly improved in selected populations. Compared to 2% in C0, about 34% of lines superior in both FHB resistance and agronomic traits in C4F1 were selected to enter the conventional breeding program for further evaluation. Sixty three semidwarf lines superior in
both FHB resistance and yield potential were selected from the F5 generations derived from C1F1 to C4F1. From them, two resistant cultivars with high-yielding potential were developed and commercialized in the Lower Yangtze Valley.
Recurrent selection appears to be highly effective and feasible in shifting the average FHB response of the intermating population
in the desirable direction, thereby enhancing the frequency of resistant individuals.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
Tef is a staple cereal of Ethiopia in high demand by consumers. In order to cope up with this high consumer demand, productivity
per unit of land must increase through the development and use of high-yielding varieties. To this effect, the National Tef
Research Project has long been striving towards the development of high yielding varieties through direct selection from germplasm
and concentrating favourable alleles through hybridization and selection, despite the tedious crossing technique. The objective
of this study was to assess the degree of genetic variation in F2 populations of tef as a basis for improving grain yield. F2 populations from 12 crosses and their parents were grown at the Debre Zeit Agricultural Research Center, Ethiopia, and assessment
was made on eight traits on individual plant basis. Eleven of the 12 crosses showed substantial genetic variation for grain
yield and its components, indicating the potential for improvement through selection. Moreover, grain yield, plant weight
and yield related traits showed moderate to high heritability values (17–80%). In all the crosses, tiller number, panicle
weight, yield per panicle and panicle length showed significant (P ≤ 0.05) and positive association with grain yield. Considering the degree of genetic variation and heritability values, emphasis
should be given to selected crosses in an effort to developing high-yielding tef varieties. 相似文献