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1.
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
2.
Summary True protein content among tubers within a plant of Solanum tuberosum cv. Oneida was found to be negatively correlated with tuber size. A similar study of S. phureja genotype 148-17 revealed no correlation. Tuber protein was determined for 250 genotypes in each of four hybrid potato populations in a factorial mating design with four potato cultivars as stylar parents mated to four groups of pollen parents (4x cultivars, 4x high protein selections, 2x S. phureja, 2x high protein S. phureja). The hybrid population derived from the 4x high protein selections was significantly higher in protein content than the other populations. High estimates of general combining ability for tuber protein content were found for both stylar and pollen parents. Poor photoperiodic adaptation to growing conditions in northern latitudes was a possible explanation for the variable protein phenotypes typical of S. phureja and the lack of transmission of the high protein character in phureja to 4x-2x hybrids. Although protein content was negatively correlated with total yield, high protein segregates with good yield potential were identified in all four populations.Scientific Journal Series Article 11, 616 of the Minnesota Agricultural Experiment Station. 相似文献
3.
Summary F1 hybrids between Solanum phureja and S. chacoense were studied in a new approach to enhance wild diploid potato species using adapted S. phureja clones as the female parent. S. chacoense parents had few tubers, whereas S. phureja parents had been previously selected for tuberization under long days. Twenty hybrid families were evaluated for haulm vigor, vine maturity, stolon development, frequency of tuberization, tuber set, tuber yield and average tuber weight under naturally occurring increasing or decreasing photoperiods in spring and fall growing seasons in Morocco. The hybrid plants were more vigorous, later maturing with thicker stolons in the spring season. Frequency of tuberization and tuber set did not vary with season. Tuber yield and average tuber weight were higher in fall; the maximum yield was 2.4 and 4.6 kg per hill under spring and fall conditions, respectively. Remarkable variation was found both between and within hybrid families for all traits in this first cycle of enhancement. The selection of vigorous, fertile clones incorporating the S. chacoense genome is possible by using S. phureja as an adapted germplasm source. 相似文献
4.
Twenty-one (near) pentaploid hybrids between sexually incompatible Solanum
commersonii [2x(1EBN)] and cultivated S. tuberosum [4x(4EBN)] were characterized for tuber traits and fertility. A number of genotypes resembled the S. tuberosum type in terms of stolon length and eye depth and produced tubers under long day conditions. Tuber yields were not as high
as expected, probably due to lack of adaptation of the S. commersonii genome to the environmental conditions in southern Italy (on average 325 g·pt−1 and 285 g·pt−1 in 2003 and in 2004, respectively). Compared to 2004, in the summer of 2003, characterized by extremely high temperatures,
hybrids gave a higher tuber yield than the S. tuberosum control, suggesting that in our environmental conditions the wild S. commersonii genome, rather than resulting in heterosis for tuber yield, provides better adaptation to harsh environments. Although aneuploidy
has often been associated with reduced fertility, several hybrids were fertile in crosses with S. tuberosum when used as female parents. In particular, the average berry set and number of seeds per berry were 38.2% and 31.8%, respectively.
Based on significant relationships between ploidy levels and all yield and fertility data measured, the presence of extra
chromosome affected the parameters considered: tuber yield in 2003 and 2004, percentage of fruit set, number of seeds per
berry and number of seeds per pollinated flower. Regression analysis also indicated that “Residuals” were significant for
all parameters measured. Therefore, additional factors (e.g. the genetic makeup of hybrids) may be key to fertility and yield. 相似文献
5.
B. Maris 《Euphytica》1986,35(2):465-482
Summary Fifty-five populations from crosses of three Solanum tuberosum ssp. tuberosum cultivars and seven selected S. tuberosum ssp. andigena clones adapted to the northern temperate zone have been studied in the seedling and the first and second clonal generation. This paper only deals with the effect of seed tuber weight on various important agronomic characters which are selected for in early clonal generations, independently of the type of crosses.The results showed that a distinction has to be made between the effects of differences in seed tuber weight within and between seedlings, i.e. genotypes. The effects on the first clonal generation of differences in weight of the tubers within seedlings and those of the first heaviest tubers between seedlings were similar and comparable to seed tuber weight effects within cultivars. In contrast to the within seedlings effects the between seedlings effects proved to be heritable. This is concluded from the fact that, on average, independent of seed tuber weight seedlings with larger first heaviest tubers performed better in the second clonal generation than those with smaller ones. Notably plant height, general impression, date of maturity and particularly tuber yield and mean tuber weight in the second clonal generation were related to the weight of the first heaviest tubers of the seedlings. The potentialities of these findings for an early generation selection are discussed. 相似文献
6.
Field experiments were carried out in order to evaluate 4x‐2x families derived from crosses between elite 4x potato cultivars and 2x Tuberosum‐Solanum tarijense and 2x Tuberosum‐Solanum berthaultii clones. Three traits were assessed: total tuber yield (TTY), haulm maturity (HM) and general tuber appearance (GTA). The degree of heterosis of these hybrid families was evaluated by comparison with the respective 2x and 4x parents as well as with seven 4x cultivars. The parental haploid species hybrids derived from S. berthaultii and S. tarijense combined two or more positive horticultural characteristics. Expressed as yield percentage of the 4x parents, the TTY of the families ranged from 53% to 246%. For TTY, the best 4x‐2x hybrid family ranked better than seven out of nine elite 4x cultivars. Some families had GTA scores in the range of the highly selected 4x cultivars. The families, however, were generally later maturing than the 4x parent group. Specific combining ability for TTY and GTA were the only two significant sources of variation observed in this genetic material. Parent‐offspring correlation coefficients were low for all traits, and indicated that parental performance would not be informative at either ploidy level. These results parallel previous investigations with distinct haploid species hybrids where a 4x‐2x breeding scheme was found to be an effective strategy for increasing progeny TTY over the 4x parents. However, the high degree of heterosis for TTY along with good GTA scores observed in certain cross combinations derived from these unadapted 2x species was a somewhat surprising result. Thus far, the importance of these two South American wild potato species, from the potato‐breeding standpoint, has been limited to the fact that they are natural reservoirs of major genes controlling resistance against important diseases and insects. However, the level of performance of some 4x‐2x families in comparative assays with elite cultivars suggests the unanticipated possibility of introgressing genetic factors from S. berthaultii and S. tarijense with positive effects on quantitative traits of horticultural importance along with these major resistance genes. 相似文献
7.
Summary Selection criteria for agronomic characters in a potato breeding program at the diploid (2x) level may differ from selection criteria used when selecting breeding lines at the tetraploid (4x) level. Differences between selection criteria are expected, (1) when expression of the characters is different at both ploidy levels and/or (2) when the effect of diploid breeding lines on agronomic characters of tetraploid progenies is different from the effect of tetraploid breeding lines. In this investigation sets of diploid and tetraploid progenies, each set derived from the same 2x.2x cross, were compared as to the expression of six agronomic characters. Diploid progenies had significantly lower yields (due to smaller tubers) and significantly higher under water weights than tetraploid progenies. Vine maturity and chip colour were similarly expressed at both ploidy levels. Correlations between yield and yield components, and between under water weight and chip colour were similar at both ploidy levels. The lower yields and higher under water weights found in diploids point to the need of different selection criteria for selecting diploid and tetraploid breeding lines. 相似文献
8.
M. Maris 《Euphytica》1989,41(1-2):163-182
Summary The main aim of the experiment was to study the behaviour of seven long-day adapted clones of Solanum tuberosum ssp. andigena (A) and three varieties of S. tuberosum ssp. tuberosum (T) in an incomplete diallel cross. The four groups of crosses, TxT, TxA, AxT and AxA, held 2, 12, 20 and 21 populations, respectively. Eleven of the intersubspecific crosses were exact reciprocals. Thirty random clones per population were grown as second clonal generation in an incomplete block design with four replications in plots of two plants per clone in 1980, the parents included in many plots. Data were recorded on ten characters.The results showed that group TxA gave the highest tuber yield and AxT the second highest. The F-values indicated highly significant genotypic effects for all characters in all populations. The mean genotypic coefficients of variation (GCV), were the highest for group AxA for all characters. The ANOVA, based on population means showed significant mean squares for general combining abilities (GCA) and for differences of reciprocalls for all characters; the specific combining ability (SCA) mean squares were significant only for date of emergence, plant height and haulm type. Almost all GCA effects of the parents were significant positive or negative. Several populations showed also significant SCA effects. The correlations between the GCA effects and the parental values were of about the same magnitude as the heritabilities; those between the population means and the midparental values were slightly lower.Compared to the midparental values, most populations showed significant positive heterosis for date of emergence, haulm type, number of tubers and under water weight; all populations had significant negative heterosis for mean tuber weight and nearly all for plant height and general impression. All populations from groups TxT and AxA had significant negative heterosis for tuber yield and so had 13 out of the 20 populations from group AxT, while seven of the 12 from group TxA showed significant positive and four significant negative heterosis. The average heterosis for tuber yield of group TxT was –11%, of TxA 3.4%, of AxT–9% and of AxA–18%. The highest mean tuber yields were obtained from crosses with a very high yielding A-parent as female, while the heterosis was negative. Though significant differences between the 11 reciprocals occurred for all characters, consistent differences occurred only for tuber yield. Averaged over the 11 crosses the TxA populations outyielded their exact reciprocals by 10.7%. For the highest tuber yields in A-T crosses, therefore, the tuberosum cytoplasm seems to be preferable. By contrast for a high male fertility the andigena cytoplasm is preferable. 相似文献
9.
Summary The objectives of this research were to evaluate the response to day length and the yield stability of environments of 4x families from 4x×2x crosses in potato. Twenty families from crosses between 4x female parents with different genetic backgrounds and 2x parents, which formed 2n pollen by first division restitution and were selected under short days, were evaluated in four locations in Peru (short days) and during two years at Rhinelander, USA (long days). Results from the USA indicate that the 4x progeny from 4x×2x crosses were very late maturing and poor yielding.Further, vine maturity, tuber size and tuber number are highly correlated with the percentage of Tuberosum germplasm in the parentage. Results from Peru indicate that most 4x×2x families had high tuber yield, stability for yield and high dry matter content. The lack of correlation between rank order of the parental value, based on progeny testing, of the male and female parents among short day locations and between short and long day environments indicates that selection of parents must be done in each location in which the final product, either a family or a clone, will be used.International Potato Center (CIP) 相似文献
10.
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
11.
A. E. F. Neele 《Euphytica》1990,48(2):159-166
Summary The inheritance of potato tuber yield was studied considering the seasonal course of harvest index. Harvests of several progenies and their parents were performed at intervals and fresh weight of foliage, underground stems, tubers and stolons was assessed.Tuber yield depends on the time of tuber initiation and the proportion of the assimilates allocated to the tubers, as reflected in the increase rate of harvest index. The time of tuber initiation of the progenies was associated with the time of tuber initiation of the earliest tuberizing parent. The mean increase rate of the harvest index of the progenies was in most cases equal to the mean values of parents, however in crosses combining early with late maturing parents the rate equaled the value of the maternal parent. Using these relations, differences in harvest index between progenies can be predicted with a high degree of precision by using the harvest index parameters of the parents. This estimated harvest index showed a fairly good correlation to tuber yield at mid-September and can be used in the prediction of the yield of the progeny. The use of the mid-parent value for this purpose is not suitable. 相似文献
12.
Summary Yield components including total tuber yield, total tuber number, vine maturity, vine vigor and average tuber weight as well as seed germination and pollen stainability were studied in 28 exact reciprocal hybrid families, between 12 Solanum tuberosum Group Tuberosum (haploid) (TH) and 12 S. tuberosum Group Phureja (PH) clones in a NC Mating Design II in 4 sets of 3 by 3 reciprocal hybrids at three locations, one in Minnesota (USA) and two in Morocco. TH parents were insensitive to daylength whereas most PH clones required critical photoperiods equal to or less than 14 hours for tuberization. Mean reciprocal differences were significant for most traits at all 3 locations. Hybrids with TH cytoplasm were superior to those with PH cytoplasm by 18% for tuber yield, 21% for tuber number, and 9% for vine maturity, but inferior to hybrids with PH cytoplasm by 11% for vine vigor and 19% for time to reach 80% seed germination. Reciprocal differences were not detected for average tuber weight. Six reciprocal crosses revealed significant differences for pollen stainability but the overall mean difference (one location) was not significant. Possible reasons for the observed reciprocal differences included gamete selection, pseudo-self-compatibility and/or interaction of cytoplasm with both nuclear genes and environment. Differences for critical photoperiod of TH and PH parents were also demonstrated as a probable source of reciprocal differences.Scientific Journal Series Article 14896 of the Minnesota Agricultural Experiment Station supported in part by the U.S. Agency for International Development, contract no. 608-0160, IAV Morocco Project. 相似文献
13.
Summary Sixty-two 2x families were generated by intermating 16, 2x clones and evaluated for resistance to potato tuber moth (PTM), Phthorimaea operculella under natural infestation in a storage at San Ramon, Peru and in laboratory tests. The following conclusions could be drawn: (1) relatively simple inheritance was observed for resistance derived from Solanum sparsipilum (spl), (2) the high level of resistance of the original spl has been transferred, undiminished, into an advanced 2x population, (3) simple phenotypic selection was successfully applied to transfer resistance into an improved 2x population, (4) there was a strong indication of reciprocal effects, however spl cytoplasm is not essential for the expression of nuclear resistance genes, (5) antibiosis and antixenosis are the mechanism of PTM resistance in this population, and (6) 4x × 2x crosses could be used to transfer the resistance into commercial cultivars. 相似文献
14.
Summary Somatic hybrids between Solanum tuberosum L. cv. Gracia (2n=4x=48) and Solanum brevidens Phil. (2n=2x=24) were produced via fusion of mesophyll protoplasts. Selection of the protoplast derived putative hybrid calli was based on their vigorous growth. Additive isozyme patterns and chromosome numbers as well as the expression of parental morphological characters have proved the hybrid origin of the selected regenerants. Extensive chromosome loss during the regeneration process resulted in aneuploid hybrids with high frequency. Genomic instability could not be detected in these plants during the period of vegetative propagation. Regenerants from hybrid tissues exhibited wide morphological variation especially in tuber formation. The detailed morphological analysis based on the use of multivariate method (principal component analysis, PCA) enabled to identify morphological groups among the hybrid clones. The positioning of hybrid clones in the PCA space could not be correlated with chromosome numbers. The genomic ratio represented by the tetraploid and diploid parents influenced the morphology of somatic hybrid population according to the applied analytical system. Two selected hybrid clones have exhibited an intermediate degree of frost tolerance compared to the parents, based on the recovery of plants from lower buds after freezing of potted plants. 相似文献
15.
Summary Resistance toMeliodogyne chitwoodi races 1 (MC1) and 2 (MC2) andM. hapla (MH) derived fromSolanum bulbocastanum was introduced into the cultivated potato gene pool through somatic fusion. The initial F1 hybrids showed resistance to the three nematodes. Resistance to reproduction on roots by MC1 was accompanied by resistance to tuber damage in F1 clones. Tuber damage sometimes occurred, however, in hybrids of BC1 progeny resistant to reproduction on roots when MC2 and MH were the challenging nematodes. Resistance to reproduction was transferred into BC1 individuals, but a greater proportion of BC1 progeny was resistant to MC1 than to MC2 or MH. Resistance to MC1 appears to be dominant and discretely inherited. F1 and BC1 progeny were pollen sterile, but seed were produced from crosses using cultivated tetraploid pollen sources. Approximately 11 and 33 per cent of pollinations produced berries on F1 and BC1 pistillate parents, respectively. Seed yield increased fourfold overall in crosses with F1 compared to BC1 individuals.Abbreviations MC1
Meloidogyne chitwoodi race 1
- MC2
Meloidogyne chitwoodi race 2
- MH
Meloidogyne hapla
- Rf
Reproductive factor 相似文献
16.
Summary Somatic hybrids of diploid amylose-free (amf) Solanum tuberosum and diploid S. brevidens were made by Poly-Ethylene-Glycol (PEG) or electrofusion methods. For the isolation of interspecific hybrids the use of selection markers (kanamycin and hygromycin resistance) was useful but not essential. In this 2x+2x interspecific combination 4x and 6x somatic hybrids were obtained. Seed set was the best in 4x×4x (S. tuberosum) backcrosses, but seed germination was the best in 6x×4x combinations, using in vitro germination of unripe seeds harvested 25 days after pollination. A high degree of pollen stainability (30–40%) was observed in 7 tetraploid hybrids and very low in all hexaploids. After iodine staining, the recessive amf marker was expressed by a red colour instead of blue, visible in starch-containing cells like columella cells of root tips, (micro)tubers or microspores. As expected, complementation was observed in starch-containing cells of the fusion hybrids. Segregation of the amf marker was clearly observed in microspores of 4x and 6x hybrids. Segregation ratios in the 4x hybrids showed variable recombination frequencies. In the backcross progeny of hexaploid F12-5 with a tetraploid amf mutant one amylose-free recombinant among 67 plants was found, indicating the occurrence of meiotic recombination in the megaspore mother cells. 相似文献
17.
The degree of heterosis for total tuber yield (TTY) and total solids (TS) in 4x‐2x crosses was estimated by comparing the performance of 12 families with their respective parents in two locations in Wisconsin (USA). The parental 2x clones were Phureja‐haploid Tuberosum hybrids with 2n‐pollen production by first‐division restitution. The general combining ability (GCA) and specific combining ability (SCA) were estimated for TTY, TS, vine maturity (VM), length of tuber sprout dormancy (LD), and tuber eye depth (ED). Family performance for TTY ranged from 74 to 146% at Hancock (E#1) and from 77 to 287 at Rhinelander (E#2) when compared with that of the 4x parent group. For VM, the families were late maturing, but a few precocious ones were identified. For TS, the families had heterosis of 5.1% over the 4x parent group. The families had slightly higher ED values than the 4x parents, but families with values within the commercial range were identified. The family average for LD (54 days) was closer to the 2x group (51 days) than to the 4x group (88 days). The direction and magnitude of the parent‐family relationships were variable. The 4x parent TTY was correlated with progeny in E#1 but not E#2. The 2x parent VM had correlation with the offspring at E#2 but not at E#1. The type of gene action had a trait‐specific expression. Significant SCA and GCA variances were observed, suggesting that additive as well as non‐additive genetic effects were operating. The 4x‐2x crosses were able to generate heterotic families for TTY and TS in combination with other useful traits. However, no promising results were found for LD because of the apparent dominance of the short‐dormancy phenotype. This result indicates the need of additional selection and breeding efforts for some specific traits when using S. phureja‐derived germplasm. 相似文献
18.
Dilson A. Bisognin David S. Douches Kazimierz Jastrzebski William W. Kirk 《Euphytica》2002,125(1):129-138
The objectives of this study were to evaluate the use of potato (Solanum tuberosum L.) late blight (Phytophthora infestans (Mont.) de Bary) resistant parents in cultivar development and identify superior clones possessing moderate to high late
blight resistance combined with acceptable maturity and tuber quality. Ninety-five crosses were made between eight unadapted
parents with reported late blight resistance (B0718-3, Bertita, Bzura, Greta, Libertas, Stobrawa, Tollocan and Zarevo) and
susceptible parents (cultivars or advanced breeding clones) adapted to North American growing conditions. A total of 408 field
selected clones were assessed for late blight resistance in the greenhouse and in the field using a mixture of US8 P. infestans isolates (A2 mating type, metalaxyl resistant) that overcame all known R-genes except R8 and R9. Clones with ≤ 10% infected
foliar area in the greenhouse test or ≤ 0.30 RAUDPC (relative area under the disease progress curve) value in the field in
1998 were re-tested in 1999. A total of 118 (29% of 408) putative late blight resistant clones were selected. The eight late
blight resistant parents differed in both the ability to transmit late blight resistance and in the level of resistance transmitted
to the progeny. The Tollocan and B0718-3 families (half-sib progeny) had the greatest degree of resistance and frequency of
resistant clones. Scott-Knott cluster analysis ranked 79 clones (67% of 118) in the high and moderate late blight resistant
groups. Among these 79 clones, 19 clones had vine maturity equal to or earlier than mid-season combined with acceptable tuber
quality. Further selection in 2000 resulted in eight advanced selected clones (six from Tollocan and two from B0718-3 families)
with the same level of resistance as the parent combined with vine maturity and tuber quality equivalent to Atlantic, a standard
cultivar for chip processing in North America. The results indicate that this breeding approach can be used to select parents
for late blight resistance breeding and to identify superior clones with high levels of late blight resistance and marketable
vine maturity and tuber quality.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Summary The possibility of combining anew the genomes of wild and cultivated progenitors of triploid S. x juzepczukii and pentaploid S. x curtilobum by following the known evolutionary pathway of these species was investigated.The resynthesis of S. x juzepczukii was easy, and a wide range of synthetic forms was bred. Among these were forms with higher frost resistance (-5°C) than has been found in natural S. x juzepczukii. The total tuber glycoalkaloid content of several synthetic hybrids was lower than or as low as that of natural clones. Most synthetic hybrids were more vigorous than natural S. x juzepczukii and produced about the same types of tubers as are found in the natural range of variation. The best diploid parents were found in the species S. goniocalyx.The attempt to resynthesize pentaploid S. x curtilobum has not been successful but tetraploid plants were obtained in the process. An explanation for the occurrence of tetraploids resulting from triploid x tetraploid and/or diploid crosses is offered.The newly bred tetraploids contain at least one genome from S. acaule (possibly two) and hybridize easily with ssp. andigena. They thus provide a means for the transfer of S. acaule germ plasm into the tetraploid cultivated gene pool which would profit from the frost resistance of S. acaule. 相似文献
20.
Summary A number of reports have indicated differences in reciprocal families of Solanum tuberosum when intergroup hybrids were studied. Questions have been raised concerning the potential magnitude, frequency, and genetic basis for such differences. In this study, exact reciprocal crosses were made using parents characterized by different maturities and having different cytoplasmic sources within Solanum tuberosum in order to substantiate previous claims of reciprocal differences and to clarify the nature of such differences.Field trials revealed reciprocal differences which were large and highly significant. Reciprocal yield differences of up to 115% were observed when parents of opposite maturities were used. In seven crosses, the higher-yielding reciprocal always had the higher-yielding parent as the maternal parent. Significant reciprocal differences for flowering and vine maturity were also observed between some families. The F2 populations were generated for one set of reciprocals and the reciprocal differences in the F2 generation seemed to be substantially reduced relative to the F1 generation.It is concluded that the occurrence of large reciprocal differences seems to depend more upon having parents of opposite maturity than upon the taxonomic origin of the parent's cytoplasm. This, in conjunction with the reduced F2 reciprocal differences, suggests that observed differences may be due to very persistent maternal effects or a type of dauermodification, rather than true cytoplasmic inheritance.Cooperative Investigation of U.S. Department of Agriculture, Science and Education Administration. Agricultural Research and the Wisconsin Agricultural Experiment Station. 相似文献