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1.
Summary Through recurrent selection and progeny testing, five bitter almond genotypes have indicated dominance of resistance for the root-knot nematode Meloidogyne javanica.All progenies from reciprocal crosses of resistant bitter almonds x susceptible sweet almonds were found completely resistant in four out of five bitter almond progenies. One selection showed near complete dominance of resistance. Progenies of resistant peach x susceptible almond cultivars segregate as to resistance, thus pointing to a possibly different mode of inheritance of nematode resistance in resistant peach as compared with almond. 相似文献
2.
Bitter flavour of the almond kernel is due to the cyanoglucoside amygdalin and has been the first characteristic considered
in breeding programmes. In such programmes, the seedlings from sweet-kernelled parents were used to study the transmission
of bitterness, which was shown to be a monogenic characteristic, the sweet flavour being dominant. The aim of this work was
to investigate more deeply the inheritance of bitterness in almond, by studying for 2 consecutive years the bitter flavour
in 169 seedlings of 9 families (obtained exclusively for this purpose), one or both parents being bitter-kernelled. With the
exception of the presence of slightly bitter seedlings, the results support the hypothesis of monogenic inheritance of this
trait, the bitter flavour being recessive, although other factors could have a slight influence on the expression of this
characteristic. Heterozygous individuals showed sweet, slightly bitter or year-changeable (sweet-slightly bitter) phenotypes.
Our results demonstrated the possibility of using as parents bitter-kernelled individuals with some outstanding characteristic
desirable for transmission to the progeny, always in combination with a homozygous sweet progenitor. 相似文献
3.
Summary Gene action and heritability of groat protein percentage were determined in F1, F2, and F3 generations of nine crosses between three Avena sativa L. cultivars and three A. fatua L. selections. Relationships among groat protein percentage, grain yield, and 100-seed weight also were evaluated. The three A. sativa parents were Dal (high grain yield and intermediate groat protein percentage), Goodland (low grain yield and high groat protein percentage), and Stout (high grain yield and low groat protein percentage). The three A. fatua parents were chosen for the study on the basis of vigorous plant growth and high groat protein percentage. The study was conducted at Madison, Wisconsin in 1979 and 1980.There was partial dominance towards low groat protein percentage. Narrow sense heritability estimates for groat protein percentage were low in Dal and Goodland crosses and intermediate in Stout crosses. In the F2 generation, groat protein percentage was significantly higher in shattering than in nonshattering plants in 1979, but not in 1980. There were significant, positive correlations between groat protein percentage, 100-seed weight, and grain yield in F1 and F2 generations, but they were not large numerically. Relationships among these traits were either negative or nonsignificant in the F3 generation. Although our results indicated that selection for higher groat protein percentage is possible when a low protein A. sativa cultivar is used, most of our simple cross progenies from A. sativa x A. fatua crosses had weak straw and were susceptible to crown rust (Puccinia coronata
Cda. var. avenae
Fraser and Led.). 相似文献
4.
Paul E. Hansche 《Euphytica》1990,49(3):263-271
Summary Dwarf peach trees require only 1/4th the space of standard trees and thus reduce the cost of experiments in which the tree is the experimental unit, by 75%. Or, put another way, they facilitate estimates of tree performance, in experiments of the same size, that are 50% more precise than those obtainable from standard trees. The objective of this study was to determine if the almond tree could be genetically compressed (dwarfed) to facilitate discrimination of genetic and cultural manipulation on its productivity, to facilitate genetic manipulation, and to increase its productive efficiency.The results obtained indicate the almond tree can be dwarfed (compressed), by the dw gene of peach. interspecific crosses of dwarf (dw/dw) peach, P. persica, with almond, P. amygdalus, followed by backcrosses to almond revealed: 1. Plant stature and node density vary widely among the dwarf (dw/dw) inter species hybrids. The heritabilities of these traits are high. 2. Spur density also varies widely. Its mean is high and its heritability is very high. 3. The dwarf inter species hybrids produce flowers copiously. However, at 22 months of age the flowers of most seedlings are sterile, apparently due to abnormal pistils. Consequently, average productivity is very low. However, some of these dwarf P. persica × P. amygdalus hybrids do express moderate to high productivity. Further, the heritability of productivity, among the seedlings expressing some degree of fertility, is very high. Consequently, further backcrosses to almond are expected to rapidly restore fertility and productivity. The yield potential of dw/dw dwarf almonds will remain unknown until fertility is restored. 相似文献
5.
Summary Cultivated almonds (Prunus dulcis (Miller) D.A. Webb) in Morocco are still propagated from seeds by farmers to overcome transplant failure of grafted trees. Almond collections in southern Morocco conducted since 1975 have resulted in the selection of clones planted at 3 experimental stations. Principal component analysis (PCA) was used to compare kernel, nut, leaf, and growth habit characteristics among 67 selected Moroccan clones and 14 introduced cultivars. Clustering of clones from similar countries and collection areas would suggest the existence of different almond populations. The Moroccan clones did not cluster separately from the foreign cultivars. Three Moroccan clones had exceptionally large nuts and kernels while 7 selections had high yield potential due to high spur density. Moroccan selections tended to be characterized by small leaves in comparison to foreign cultivars. No evidence was found to suggest the existence of separate populations within the Moroccan almond germplasm. 相似文献
6.
Summary Pollen grains from selected cutivars of almond [Prunus dulcis (Mill.) D. A. Webb] and peach (Prunus persica
Batsch L.) were exposed to a range of temperatures between 1°C and 34°C on a thermogradient plate. Pollen germination at temperatures below 9°C was conspicuously greater in almond than peach. Miximal germination percentages were attained at about 16°C (almond) and 23°C (peach). The two species did not differ in their capacity for pollen tube elongation over a broad range of temperatures. Maximal pollen tube elongation occurred at temperatures 5°C to 8°C higher than maximal pollen germination. Species affiliation appeared to be of much greater consequence than chilling requirement or bloom date of the sporophyte in predicting gametophytic response to temperature. 相似文献
7.
Summary It was attempted to overcome crossing barriers between the cucumber (Cucumis sativus L.), the melon (C. melo L.) and two wild Cucumis spp. (C. metuliferus
Naud. and C. zeyheri 2x Sond.) by application of aminoethoxyvinylglycine (AVG) and by limiting the amount of rooting substrate. The reciprocal crosses between both wild species were used as a model system.Crosses between C. metuliferus and C. zeyheri 2x succeeded well if the maternal plants were grown in containers of 10 or 25 1 instead of in open soil. This treatment also improved crossability in the cross C. metuliferus x C. melo. It strongly enhanced the number of female flowers per plant in C. metuliferus. Application of AVG to pollinated flowers initially seemed also to improve crossability in these cross combinations, but later on this effect was not found again.Significant genetic variation for crossability was found in C. zeyheri 2x. Rare plants yielded numerous fruits with embryos after crosses with C. metuliferus and also with C. sativus. Clones from these plants gave similar results.Excessive temperature and radiation decreased crossability especially in crosses with C. metuliferus and C. sativus as maternal parent. 相似文献
8.
Summary The origin and nature of the diploid cultivated potato species S. ajanhuiri Juz. et Buk. was studied. Several lines of evidence indicate that S. ajanhuiri might be derived from natural crosses between primitive cultivars of the diploid species S. stenotomum and the wild species S. megistacrolobum. Morphological comparisons were made between S. stenotomum x S. megistacrolobum F1 hybrids and naturally occurring S. ajanhuiri to investigate this hypothesis. Comparisons were also made between S. ajanhuiri x S. stenotomum crosses and the F2 generation of the first-mentioned cross.Crosses between the two major groups of S. ajanhuiri cultivars, Ajawiri and Yari, showed not only genetic breakdown but also a wide range of phenotypic variation similar to those of artificial F2 families of S. stenotomum x S. megistacrolobum. Furthermore, there was strong evidence showing that the Yari group of S. ajanhuiri could almost certainly be an F1
S. stenotomum x S. megistacrolobum hybrid, whereas the Ajawiri group could be a backcross of an F1 hybrid to S. stenotomum. These results added further support to the hypothesis of a hybrid origin of S. ajanhuiri, as well as indicating its putative parents. It is suggested that this hybridogenic taxon be retained at the species level under the name Solanum x ajanhuiri. 相似文献
9.
H. G. Nass 《Euphytica》1979,28(1):161-167
Summary Three methods were evaluated as potential aids in identifying superior crosses early in the breeding program: (1) F1 yield, (2) F2 yield, and (3) midparental yield. Two sets of spring wheat (Triticum aestivum L. em. Thell.) crosses and parents were evaluated in replicated single row plots in F1 and in replicated multi-row plots in F2 over a period of five years. On the basis of F1 yields, two of the highest yielding and two of the lowest yielding crosses in each set were chosen for a more detailed selection study in subsequent generations.In Set 1, random F2 head selections for each of the selected four crosses were evaluated in 3-row yield plots in F4. In Set 2, F2 plant selections were made on the basis of head weight and the highest yielding 10% evaluated for yield in F4.Lines of crosses identified as high yielding in F1 had significantly greater mean yields in F4 than those of crosses that were low yielding in F1. The high yielding crosses had three to four times as many lines yielding in the top 10% in F4 than did the low yielding crosses.Correlations for yield were obtained between F1 and F2 in different years, F2 and midparents in the same year, lower or no correlations between F1 and midparents in the same year, and no correlations between F1 and midparent and F2 and midparent in different years. It is suggested that larger plot sizes rather than single rows be used to evaluate parents.Midparental yield, F1 yield and F2 yield tests are recommended as a progressive set of screening tests for a given set of crosses to effectively maintain the superior crosses in the breeding program. 相似文献
10.
Summary Reciprocal crosses between 13 cultivars of Zinnia elegans Jacq. and one source of Z. angustifolia HBK resulted in interspecific hybrids. Florets examined 14 days after pollination showed that all 13 cross combinations of Z. angustifolia x Z. elegans yielded embryos in 47.2% of the florets pollinated. Six cross combinations of Z. elegans x Z. angustifolia produced embryos in 4.6% of the total Z. elegans florets pollinated. Interspecific crosses resulted in seed-propagated hybrids when Z. angustifolia was the maternal parent. Hybrids were obtained from reciprocal crosses between the two species when embryos were excised and cultured. Morphologically, most hybrids resembled Z. angustifolia but were sterile. Colchicine treatments of selected sterile hybrids resulted in shoots producing fertile inflorescences. Preliminary tests showed that hybrids were resistant to powdery mildew (Erysiphe cichoracearum DC ex Mecat).Scientific Article No. A 3108, Contribution No. 6173 of the Maryland Agricultural Experiment Station, Department of Horticulture. 相似文献
11.
Summary Interspecific hybrids were generated from crosses between 4 Zinnia angustifolia clones (maternal parents) and an inbred line of Z. elegans Orange King (paternal parent) to investigate the influence of Z. angustifolia genotype on morphology and flowering of hybrids. Leaf length, leaf width, flower diameter, number of ray petals, and days to flowering of interspecific hybrids were significantly influenced by Z. angustifolia clonal genotype. Genetic analysis of hybrid morphology and development was performed using 2 parental Z. angustifolia clones and 18 F1 (9 seedlings from each of 2 populations generated from reciprocal crosses between parental clones) as maternal parents in crosses with Z. elegans Orange King. Genotype of Z. angustifolia significantly affected plant height, fresh weight, number of nodes, and days to flowering of interspecific hybrids. Control of these traits was through the Z. angustifolia nuclear genome. Improvement in interspecific hybrid morphology or development, i.e., shorter stature, earlier flowering, or larger flowers, may be possible by selection of superior-performing Z. angustifolia clones as parents. 相似文献
12.
Summary The almond of commerce (Prunus dulcis (Mill.) D.A. Webb) is self-incompatible (SI) and requires honey-bees to effect the transfer of pollen among cultivars that flower simultaneously. Four year old trees from the F2 generation of several peach x almond hybrids were studied to determine whether self-compatibility (SC) and the potentiality for natural, i.e., abiotic, self pollination (NSP) are genetically related or are inherited independently. Both SC and the high potentiality for NSP are characteristic of peach (Prunus persica (L.) Batsch) but not almond. Forty percent of SC genotypes exhibited adequate NSP (SC, +NSP) for good fertility i.e., without insect-mediated pollination. The remaining 60% of SC genotypes (SC,-NSP) exhibited an average 61% reduction in fruit set on limbs bagged to exclude honeybees during anthesis relative to fruit set on open pollinated limbs. Our data are consistent with the concept that fertility is dependent upon the load of compatible pollen deposited on the stigma. Fruit set reduction on bagged limbs, compared with bagged and self-pollinated limbs, was presumably due to a) lack of/insufficient pollination for fertilization and/or b) post-zygotic abortion of genetically inferior recombinants. Selection following manual self-pollination may result in SC genotypes with or without the capacity for NSP. In contrast, significant fruit set on limbs enclosed during pistil receptivity necessitates that the genotype selected express both SC and the potentiality for NSP. 相似文献
13.
Summary Certain parent-progeny crosses were studied to determine whether several S loci acted independently or epistatically to produce incompatibility in garden chrysanthemums, Chrysanthemum morifolium
Ramat. The ratios of compatible: incompatible crosses with the original parent, as the pollen parent, were nearly 1:3, 1:1, and 1:1 for the I1, backcross (BC), and BCF2 generations, respectively. In particular, crosses between each progeny and the original parent showed that the number of compatible crosses was much higher than expected if each S locus acted independently. Therefore, interaction must have existed among pollen S alleles from different S loci. This information was used to demonstrate a method by which garden chrysanthemums could be inbred by sib mating in successive generations.Scientific Journal Series Paper Number 13,001 of the Minnesota Agricultural Experiment Station. 相似文献
14.
The use of an 8x Vaccinium produced through doubling a tetraploid hybrid with colchicine was studied as a means of facilitating gene exchange between V. corymbosum L. and V. ashei
Reade. Analysis included meiotic observations and crossability studies of the 8x plant, as well as attempting to develop 6x breeding lines. Meiotic analysis revealed the presence of micronuclei in Telphase II products and polyspory in sporads. In the crossability studies five 4x highbush plants were pollinated with 8x o2 4x pollen. Data gathered included: % fruit set, average weight/fruit, average number of seeds/fruit, average number of seedlings/pollination, and number of 6x seedlings. Octoploid pollinations were significantly lower than 4x pollinations in all parameters. One 6x plant was produced from the 4x-8x crosses but was found to be mitotically unstable, having somatic cells with chromosome numbers ranging from 48 to 168. 相似文献
15.
Summary The effectiveness of the honeycomb selection method for yield in spring wheat (Triticum aestivum L.) was evaluated using progenies from two wheat crosses, Glenlea x NB131 and Glenlea x Era. Honeycomb selection was carried out in the F2 and F3 generations, grown at the University of Manitoba in the summers of 1980 and 1981, respectively. In both generations, divergent selection was made for both high and low yield. Plants selected in the F3 generation were entered in an F4 yield test in the summer of 1982. Results of the experiment showed that honeycomb selection for yield in the F2 and F3 generations was effective in identifying parents of high- and low-yielding lines. F3 plants from highyielding F2 selections gave higher yields than those from low-yielding F2 selections by 11.5% and 13.0% for Glenlea x NB131 and Glenlea x Era crosses, respectively. The F4 yield test showed that high yielding selections from both crosses significantly outyielded by 8.9% low yielding selections and by 14.4% the unselected composite lines. It is concluded that the honeycomb selection method can be used for early generation selection in spring wheat. 相似文献
16.
self-(in)compatibility almond genotypes: A review 总被引：1，自引：0，他引：1
To compile self-(in)compatibility almond genotypes, a review of 133 commercial cultivars of wide geographical origin was made. The information gathered from own and mainly published work will be useful for both grower's cultivar choice when planting and for breeder's cross design when planning. The almond S genotypes compiled were identified using five different methods: biological (pollination tests in the field and in the laboratory) and molecular (RNases, PCR and sequencing). In most cases, genotypes were assigned after combining more than one technique. Cultivars were classified into three categories: self-incompatible (99), self-compatible (16) and doubtful self-incompatible (18). The database is divided in 9 fields (name, origin, parentage, obtention year (crossing, selection or release), S genotype, technique used, reference, consensus genotype, and cross incompatibility group). A study of the 27 S alleles already identified and their geographical distribution within the cultivated almond is also presented. The study was divided into cultivars of known and unknown parentage and the distribution of S alleles frequencies was uneven among the 133 cultivars. S allele frequencies are related to geographical origin. Some alleles (S
1, S
5, S
7 and S
8) are more frequently observed than the others among cultivars of both known and unknown parentage. In the cultivated almond, the S
f allele is only found in the Puglia region, Italy. The S
f
frequency is three times higher in cultivars released from breeding programmes than in cultivars selected by growers. From the 351 resulting possible genotypes by combination of the 27 S alleles identified only 20 CIG (0-XIX) have been established, which represents a small fraction of the whole genetic diversity of this polymorphic gene in almond. 相似文献
17.
Sharka, a disease caused by Plum pox virus (PPV), mainly affects some Prunus species, including apricot, peach and plum, and to a lesser degree, sweet cherry and sour cherry. In almond, different PPV isolates have been transmitted experimentally to the ‘Aï’ cultivar. In this study, the resistance of 10 almond cultivars to a Dideron PPV isolate was evaluated in controlled conditions by grafting the cultivars on to inoculated GF305 peach rootstocks. The results demonstrated a high level of resistance to PPV in all the almond cultivars assayed. They did not show any symptoms and were ELISA and RT‐PCR negative, despite the strong symptoms observed in their GF305 rootstocks. The implications of these results for the dispersion of PPV, and the potential role of almond as a source of resistance to PPV in other Prunus species such as peach, are also discussed. 相似文献
18.
Summary Genotypes of Phaseolus vulgaris differ in their level of resistance to Empoasca kraemeri, but the speed with which these differences can be accumulated into a resistant variety will depend on whether they can be detected in single F2 plants, and on whether the genetic control of resistance is additive. Thirty-eight homozygous genotypes were therefore grown in small plots with and without insecticidal protection, and also in simulated F2 populations containing one plant of each genotype. In addition, the F2 and F3 generations of crosses were studied. Both generations of a 13 parent diallel were grown with and without insecticidal protection. Six crosses, involving some of the parents in the diallel and two additional genotypes, were studied in more detail. Protected and unprotected F2 plants from these crosses were harvested individually, and the resulting F3 families were grown with and without protection. In all the expriments, the level of damage to the unprotected plants and the vigour of the protected plants was assessed visually by means of a numerical score, and the seed yield was measured.The performance of a single homozygous plant was a reasonable predictor of the performance of the same genotype in a small plot, but in the six crosses studies in detail, the correlations between F2 and F3 performance were low. In the analysis of the diallel cross, the significant differences among crosses were due to specific combining ability and not general combining ability. These results indicate that the genetic control of resistance is largely non-additive, and that F2 selection will probably be ineffective. However, F3 selection should be effective, and transgressive segregants for resistance should be obtainable.In some of the six crosses, the F3 families differed both in general vigour and in narrow-sense resistance to E. kraemeri, as defined by Galwey & Evans (1982). The visual assessment of damage symptoms in each plot was related to the subsequent seed yield of the plot, but was more heritable than yield. The relationship between these two variables was investigated by the genetic correlation coefficient and by an alternative method, and was found to be partly genetically determined, but partly due to the influence of environmental factors on both variables. This indicates that screening for E. kraemeri resistance should be done by means of a visual damage score in a carefully chosen, uniform environment. 相似文献
19.
Summary A number of crosses were made between diploid and tetraploid Lolium perenne plants in order to determine the degree of cross compatibility between the two different ploidy levels. The range of hybridization undertaken involved diploidxdiploid, and tetraploid x tetraploid control crossings, diploid x tetraploid crosses, tetraploid x diploid crosses and mixed pollinations. The seed set, the germination capacity of resultant hybrid seeds, and the chromosome constitution of derived seedlings was determined. In addition attempts were made to culture 12 day-old hybrid embryos from the diploid x tetraploid and reciprocal crosses.The crossing results obtained indicated no barrier to fertilization between diploids and tetraploids, but the irregular and poor development of the seed accompanied by much reduced germination, indicated unsatisfactory endosperm establishment of large numbers of triploids, as confirmed by the result of culturing embryos dissected from 12-day old seeds.In preliminary studies undertaken to determine the extent to which diploid and tetraploid ryegrass varieties intercross when grown in close proximity for seed production, Griffiths and Pegler (1966) observed a very low incidence of triploids amongst the progenies of diploid plants exposed to the pollen of tetraploid plants and also amongst the progenies of tetraploid material exposed to the pollen of diploid plants.In these and subsequent studies it was noted that only a very small proportion of the so-called fully formed seeds derived from diploid x tetraploid crosses did actually germinate. When, in 1964, propagules of clones of S.24 perennial ryegrass, well separated from one another, were placed in drills of the tetraploid perennial ryegrass variety Reveille, the proportion of florets which formed caryopses, and of caryopses which germinated was as follows (Table 1).The data (Table 1) clearly indicate that a considerable proportion of the S.24 florets had been fertilized by 2n pollen and had formed caryopses, but most of these had proved to be defective. As noted in the previous studies, the frequency of triploid seedlings was low, thus suggesting incompatibility between the n and 2n gametes for the production of viable zygotes.Of the total progenies classed as tetraploids in the early seedling stage, 80% proved to be ryegrass x tall fescue F1 hybrids. These arose as a result of free crossing with 相似文献
20.
B. Maris 《Euphytica》1990,46(1):15-33
Summary To determine whether in potatoes the tetraploid level is preferable to the diploid level, especially regarding tuber yield, four diploid (2n=2×=24) Solanum phureja x dihaploid S. tuberosum hybrid parents and their vegetatively doubled, tetraploid (2n=4×=48) counterparts were intermated, which resulted in two F1 hybrid families at both levels of ploidy. The parents and clones of the F1 families and their offspring were used in crosses in such a way that in addition Sib1, Sib2, F1×Sib1, BC1 and Sib1×Sib1 families were produced. Of the first clonal generation of the 12 2 x families and their 12 counterpart 4 x families two tubers per clone were planted in three replications in a field experiment at Sturgeon Bay in 1969; of the parents six tubers were planted in each replication. Data were recorded on 16 characters, including plant height at four different times.The ANOVA's showed significant clone effects within each family for all characters. Computed from all family means as well as from the family means per ploidy level, differences due to family were also significant for all characters except one.As at the 2 x level and at the 4 x level of ploidy the mean phenotypic correlations between characters were of similar magnitude, it is concluded that they are independent of ploidy level.With the exception of eye depth, the mean coefficient of variation was greater at the 2 x than at the 4 x level of ploidy, indicating the greatest response to selection for those characters at the 2 x level. From the differences in family means between the 4 x and the 2 x level of ploidy it was apparent that the 4 x families generally had significantly taller plants, later maturity, fewer tubers, higher mean tuber weight, more tuber yield and more dry matter yield than their counterpart 2 x families. In contrast, the 4 x parents had on the average shorter plants, lower mean tuber weight, much lower tuber yield and lower dry matter yield than their 2 x counterparts.The phenotypic correlation and Spearman's rank correlation between the family means of the 2 x and the 4 x level of ploidy were positive for almost all characters and significant for nearly half of them.From the results it is concluded that 1. in potatoes the 4 x level of ploidy is preferable to the 2 x level, and 2. the performance of 4 x families is predictable from the performance of their counterpart 2 x families.Based on results mentioned in the literature and on the present results, a continued use of S. tuberosum dihaploids in potato breeding needs to be dissuaded. 相似文献