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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. A relatively low degree of determination (R2) of both 4x and 2x parents on the performance of their 4x—2x hybrid progenies was found for all six traits studied. This implies that test crossing and subsequent progeny analysis is necessary before such parents can be used in a breeding program. Since marketable yield was found to have a higher predictability than total yield, it is the preferred yield trait to be measured. Diploids which produce 2n gametes via FDR usually give rise to 4x progenies with a greater amount of heterosis than similar progenies derived from diploids which produce 2n gametes via SDR, although such heterosis is not necessarily expressed in terms of marketable yield. 相似文献
2.
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
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.
A. Elgersma 《Euphytica》1990,51(2):163-171
Summary Seed yield in perennial ryegrass is low and unpredictable. Spaced-plant traits suitable for indirect selection for total seed yield in drilled plots would be very useful. The objectives of this investigation were to evaluate genetic variation for seed yield components and other traits among clones from three perennial ryegrass cultivars differing in seed yield and their open-pollinated progenies. Per cultivar, a random set of 50 genotypes was cloned and on each genotype seed was generated by open pollination. Clonal ramets of the parents were observed for 17 traits in 1986 at two locations. In 1987 and 1988, parents and progenies were observed as single plants in a randomized complete block design with two replications. There was little cultivar-environment interaction for most traits. The parents differed significantly for almost all traits. Half-sib (HS) families differed for only three to five traits. Broad-sense heritabilities (h2
b), based on variance components of the parents, were moderate to high; earliness had the highest hb
2. Narrow-sense heritabilities (h2
n), based on variance components among HS-families, were low to moderate and mostly not significant; for most traits h2
n estimates varied between years and cultivars. Flag leaf width and date of first anthesis showed the highest h2
n. Narrow-sense heritability estimates from parent-offspring regressions (h2
nPO) ranged from non-significant to high, depending on year and cultivar; they were generally higher than the corresponding h2
n estimates. Generally, h2
nPO was highest for earliness, flag leaf width, ear length and the number of spikelets per ear. Breeding methods that capitalize on additive genetic variance, such as mass selection, should result in improvement for these traits. 相似文献
5.
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
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.
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
8.
Nine polycross (PX) and nine different self (S1) progenies were randomly chosen from 43 selected tall fescue genotypes and evaluated for in vitro digestible organic matter (IVDOM), crude protein, neutral detergent fibre, acid detergent fibre and acid detergent lignin of whole plants, leaf blades and stems (stem plus leaf sheath) at each of four harvest dates in 1991 and 1992. Significant variation for all whole‐plant and leaf quality traits occurred among the PX progenies at the May harvest. Variation among S1 progenies was significant for almost all of the stem traits. Genetic variance components for both progeny groups were significant for almost all of the traits, confirming the presence of additive genetic variation. Heritability estimates on a progeny‐mean basis ranged from medium to high for almost all the traits of the whole‐plant and the leaf and stem fractions. The results suggest that spring would be the time at which direct selection for high IVDOM or low fibre content would be successful and that selection for leaf or stem quality traits improves whole‐plant quality. Selection for quality traits in the summer or in the autumn would be difficult since no significant genetic variability was found. 相似文献
9.
Combining ability analysis for harvest index in winter wheat 总被引：1，自引：0，他引：1
Summary Cereal breeders have used harvest index (HI) as a selection criterion in segregating generations to identify physiologically superior lines with improved partitioning of total assimilate into grain. Information on combining ability for HI of the hard red winter wheat (Triticum aestivum L.) cultivars of the Southern Great Plains is not available. A study was undertaken to examine HI of seven genetically diverse winter wheat parents, evaluate their general combining ability (GCA) and specific combining ability (SCA) effects, and study correlations of HI with several agronomic traits. The seven parents were crossed in a half-diallel mating design to produce 21 crosses. The F1's, their F2 progenies, and the parents were evaluated in replicated field tests at Stillwater and at Lahoma, OK. The combining ability analysis was performed using Griffing's Method 4, Model 1. The results showed significant variation among parents for HI. The GCA and the SCA effects were mostly inconsistent between generations and between environments. However, parents with consistently high HI and positive GCA estimates were identified. The progeny with high HI mostly resulted from parents with high GCA estimates. The correlations between HI and agronomic traits indicated that improvement in HI should also result in high grain yield, early maturity, and short plant height. 相似文献
10.
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
11.
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
12.
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
13.
Joseph Akwasi Manu-Aduening Bright Boakye Peprah Adelaide Agyeman 《Journal of Crop Science and Biotechnology》2013,16(1):23-28
Availability of genetic diversity is important in selecting suitable cultivars for crop improvement. Progenies of crosses between 19 farmer-preferred cassava landraces and Cassava Mosaic Disease (CMD)-resistant cultivar TME 11 were evaluated and compared with their maternal parents to assess their genetic variability and genetic gains based on CMD tolerance, some growth variables and root yield. The combined analysis of variance for the traits showed significant genotypic differences amongst the progenies and the parents. Apart from a few instances, the differences in replications and years were also significant. Genetic variability components showed high heritability ranging from 92.3 to 99.6% and moderately high genetic gains of 54.1 to 99.6% for the parental cultivars. Apart from canopy spread and plant height, heritability and genetic gains of the progenies were slightly lower than the parents indicating high variability within families of the progenies. The phenotypic coefficient of variation was slightly greater than genotypic coefficient of variation indicating minimal influence of environment on the genotypes. For most of the characters evaluated, the mean performance of the progenies was higher than their corresponding parental lines. Although the genotypes differed significantly (P < 0.001) for all traits evaluated, cultivars such as Afebankye, Bosome nsia, Cedi bankye, 262 Debor, Kwadaso 25, Nkaakom 57 and Sisipe were found to constitute a pool of germplasm with adequate variability. The negative correlation between CMD incidence and other traits evaluated showed significant progress made in the breeding program. 相似文献
14.
Richard G. Merrit 《Euphytica》1988,38(2):105-111
Summary Effective utilization of uniculm wheat (Triticum aestivum L.) germplasm in breeding programs requires an understanding of the inheritance of the uniculm character. The parents, F1, F2, and first generation backcrosses (B1 and B2) of two crosses, each utilizing a uniculm spring wheat line and a locally adapted winter wheat cultivar, were space planted in an experiment to acquire information regarding the genetic control of culm number. Significant F1 deviations from midparent values revealed the presence of substantial non-additive gene effects. The scaling tests of Mather and the joint scaling test detected the presence of epistasis. Hayman's six-parameter model revealed that a negative dominance effect provided the major contribution to variation in culm number, while additive x additive and dominance x dominance gene effects were of considerable importance. 相似文献
15.
Summary The first backcross and F2 progenies from triploid F1 and tetraploid F1 hybrids between B. napus and 2x and 4x B. oleracea ssp. capitata (cabbage) were studied for their general morphology, resistance to race 2 of the clubroot pathogen, chromosome number and meiotic chromosome behavior. No linkage was apparent between resistance and the major morphological characters. Unreduced gametes played a large part in the successful formation of seed of the B1 and F2 progeny. B1 plants with low chromosome numbers were selected for use in recurrent backcrosses. The potential use of anther culture to extract gametic progenies from resistant B1 and F2 plants with higher chromosome numbers was suggested. The presence of homoeologous pairing observed in all the plants is considered advantageous for selecting suitable progeny in later generations. 相似文献
16.
为分析桑树杂交后代桑叶品质性状的遗传特性,对种质创新和品种遗传改良提供材料、技术和理论支持,本研究以2个不同倍性桑树杂交亲本和组合后代群体为材料,通过对桑叶中水分、灰分、可溶性糖、粗蛋白、粗纤维、多酚类物质、黄酮类物质含量及体外总抗氧化能力等指标的测定,研究了桑叶品质性状的遗传倾向。研究结果表明：2个组合所有杂交后代不同性状遗传差异较大,其中桑叶中水分和灰分含量2个性状变异系数小于10%,遗传相对稳定,而可溶性糖、粗蛋白、粗纤维、多酚类、黄酮类物质含量及体外总抗氧化能力、清除.OH能力等变异系数较大,遗传多样性丰富,在群体中选择特异性状单株具有很大潜力。2个杂交组合后代群体中桑叶营养物质(水分、灰分、可溶性糖、粗蛋白和粗纤维)含量均值均小于相应亲本均值;活性物质(多酚类、黄酮类)含量及体外抗氧化能力(总抗氧化能力、清除.OH能力)均值均高于相应亲本均值,对杂交后代进行优良单株筛选可获得较高的遗传增益。综合分析杂交后代桑叶品质性状的遗传特性,可为桑树种质创新和品种遗传改良提供材料、技术和理论支持。 相似文献
17.
Summary Combining high fiber strength with high yield in upland cotton (Gossipium hirsutum L.) was been difficult. The cross combination, 69–120 × 6M-10, was chosen for this study because of the divergence of parents for fiber strength, seeds per boll and crop maturity. Forty F2 plants were selected in 1974 solely on the basis of visual yield and 20 plants were randomly chosen to serve as a bulk check. The F3 progenies, the bulk check, the parents and a commercial check were tested in 1975. From these results, five groups were established, consisting of four (10%) progenies each to represent high seed/boll, low seeds/boll, high fiber strength, low fiber strength and high yield in the 1976 test of F4 progenies. This experiment was conducted to (a) compare the contributions of yield components to lint yield among groups of early generation progenies (F3 and F4) and (b) determine the phenotypic correlations between yield and quality attributes. The yield components, bolls/m2, seeds/boll, fibers/seed, mean fiber length and micronaire, were included as well as fiber strength.No significant lint yield differences were found among the five groups. Progenies within groups did, however, differ in lint yield. The low and high seeds boll groups gave similar yield and fiber quality results. The low and high fiber strength groups gave similar yield but longer fiber was obtained with the high strength group.Stepwise regression analyses estimates show that the number of bolls produced per unit area, although the major contributor to lint yield for all groups, contributed only 66.9% of the total variation in the progeny group selected for high yield, with fibers/seed, mean fiber length, micronaire and seeds/boll accounting for 13.2%, 8.1%, 6.0%, and 5.8%, respectively. Correlations between the various yield components and fiber strength were low and mainly insignificant, indicating that minor alterations might be made in later generations without serious consequences.Potential gains from second-stage selective pressure upon yield-per-boll components following initial selection for lint yield are discussed. 相似文献
18.
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
19.
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
20.
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