Variability and inheritance of flowering time and duration in Actinidia chinensis (kiwifruit)

We investigated the variability and inheritance of flowering in a seedling population of diploid Actinidia chinensis Planch. We found considerable variation in time to reach 50% flowering (D50) and flowering duration (FD). D50 was highly heritable (h ² > 0.85) suggesting that this trait would respond well to selection in this population, whereas FD was greatly affected by the environment (h ² < 0.20). The results also showed that the flowering times of male vines were more sensitive to the environment than those of female vines. However, significant specific combining ability (SCA) effects could be achieved by targeting specific bi-parental combinations for breeding and selection of flowering time. The diversity in flowering traits among males will facilitate the selection of male pollinizers that coincide in flowering time with present or future female cultivars. The possibility of breeding female cultivars with a short flowering period to improve the consistency of fruit maturity at harvest is discussed.     

Selection for early flowering in progenies of interspecific crosses of ten species in the genus Dianthus

Summary Twenty-seven progenies of interspecific crosses, involving ten Dianthus spieces (D. caryophyllus, D. chinensis, D. superbus, D. barbatus, D. japonicus, D. brachyzonus, D. versicolor, D. trifasciculatus, D. serotinus and D. knappii) and some complex interspecific hybrids (Diantini genotypes and D. Allwoodii selections) were grown from seed under 8 hr days at two light intensities: 12 W/m² and 22 W/m². Observations on individual plants were made on vegetative development and date of flowering. After six months, 178 plants were selected from 23 seedling progenies and the resulting clones were compared under 22 W/m² and two photoperiods: 8 hrs and 24 hrs per day for a period of nearly six months. In the seedling stage, large differences were observed between progenies, e.g. in percentage generative plants (0–100%), plant length (3–78 cm) and plant fresh weight (0.5–68 g). Effects of light intensity were most pronounced in plant fresh weight (0.2–18 g in 12 W/m² and 0.5–68 g in 22 W/m²). Progenies of D. chinensis were the earliest to flower. Most progenies of crosses between D. superbus and D. barbatus segregated into flowering and non-flowering (rosetting) plants. In the clonal stage, most clones originating from non-flowering seedlings remained vegetative (rosetting), while all clones from flowering seedlings were either in flower or in bud within six months. Average dates of flowering of seedling progenies and of their clones were highly correlated, suggesting that selection on flowering date at the seedling stage is effective. High correlations were also found between the average flowering date of seedling progenies and the number and total weight of flowers harvested per plant in their clones within six months from planting. Overall effects of LD in the clonal stage were much less spectacular than the effects of light intensity in the seedling stage.     

Breeding for improvement of flowering attributes of winterhardy Rosa rugosa hybrids

Summary The purpose of this study was to determine at what stage of seedling development the flowering attributes in winterhardy R. rugosa hybrids could be assessed and if these attributes could be improved through breeding. The analysis of flowering was based on the duration of the flowering period and on amount of flowers produced.Most seedlings from rugosa hybrids could be assessed at an age of 3 years. The duration of the flowering period and flower productivity were not correlated. Several seedlings were improved in both attributes over the longer flowering and more floriferous parent.     

Comparative study on growth and development of some accessions of local Germplasm of Bambara groundnut (<Emphasis Type="Italic">Vigna subterrenea</Emphasis> L. Verdc.) of Nigeria in two cropping seasons

Two field experiments were conducted in April (early cropping) and August, (late cropping) 2007 at the Department of Crop Science Research Farm, University of Nigeria, Nsukka, to evaluate the agronomic and yield attributes of 13 cultivars of bambara groundnut. The results obtained showed that planting dates had significant effects (P < 0.05) on all traits measured. Significant cultivar and cultivar x planting date interaction effects were observed for days to 50% flowering. The principal component analysis showed that the first three components accounted for 85.18 and 86.81% of the total variation in the early and late planting, respectively. The traits representing the cultivars along the first principal axis were number of pods per plant and seed weight per plant for the early planting and number of leaves per plant and seed weight per plant in the late planting. Cultivars were differentiated on the basis of number of flowers per plant and plant height for the early planting and days to emergence for the late planting along the second principal axis. The cluster plot revealed that the 13 bambara groundnut cultivars were grouped into three clusters at both the early and late planting dates. In the early planting, the cultivars in cluster I are associated with high number of flowers, number of pods, and plant height, while cluster II cultivars flowered earlier and had good pod and seed yield. However, cluster III cultivars performed poorly in all the traits evaluated. During the late planting, the cluster I comprised early flowering cultivars while cluster II comprised cultivars with good vegetative growth, high number of pods per plant and seed weight per plant. Cluster III cultivars are early emerging and early flowering but have poor seed yield. The correlation coefficient for seed weight per plant was highly significant and positive with number of leaves per plant, plant height, number of flowers per plant and number of pods per plant indicating that increase in these traits will ultimately increase seed weight per plant. Thus, these traits could be considered as major seed yield contributing traits that could be given significant recognition during selection.     

Quantitative trait loci for fruit size and flowering time-related traits under domestication and diversifying selection in cucumber (Cucumis sativus)

In cucumber, the genetic basis of traits under domestication and/or diversifying selection is not well understood. Here, we reported QTL mapping for flowering time and fruit size-related traits with segregating populations derived from a cultivated × wild cross. Phenotypic data of flowering time (FT), fruit size (FS), fruit number (FN) and fruit weight per plant (FW) were collected in multiple environments. QTL analysis identified 19 QTL for these traits. We found that the major-effect QTL FT1.1 played an important role in regulating flowering time in cultivated cucumber, whereas the minor-effect QTL FT6.3 contributed to photoperiod sensitive flowering time during domestication. Two novel consensus FS QTL, FS1.4 and FS2.3, seem to be the targets of selection during breeding for the US processing cucumber. All other FS QTL were co-localized with previously detected QTL using populations derived from cultivated cucumbers, suggesting that they were under selection during both initial domestication and subsequent improvement. Results from this study also suggested that the wild cucumber is a useful resource for capturing positive transgressive segregation and novel alleles that could be explored in cucumber breeding.     

Inheritance of duration from sowing to first flowering in pigeonpea

Duration from sowing to flowering is the most important trait influencing adaptation in pigeon pea (Cajanus cajan), but the inheritance of this trait has not been elucidated clearly. Crosses were made between two early (60 to 70d) and one late (160 to 170d) flowering pigeonpea genotype and F₁, F₂ and BC₁ populations produced. These populations, comprising 60 to 100 parents, 30 F₁, 400F₂ and 40 to 50 BC₁ plants, were grown under natural (mean13.4 hd^-1) and artificially extended (to 15 hd^-1) daylength and duration from sowing to first flowering recorded. Genetic analysis of the segregation ratios, supported by Chi-square tests, indicated that the duration from sowing to flowering in each of the crosses was controlled by two genes assorting independently and with predominantly additive quantitative effects. The segregation patterns were most clearly defined in the 15 hd^-1 daylength. This revised version was published online in July 2006 with corrections to the Cover Date.     

Heritability of oil content and the onset of flowering in a population of Dimorphotheca pluvialis

To develop efficient breeding strategies for the improvement of oil content and onset of flowering in Dimorphotheca pluvialis, narrow-sense heritabilities of these characters were estimated. Forty plant progenies were tested in 2 years and heritabilities were estimated from parent-offspring regression as well as from half-sib family variance components analyses. For oil content, the heritabilities estimated by means of parent-offspring regression were 0.36 and 0.33 for 1993 and 1994, respectively. The heritabilities obtained from the variance components analyses were 0.41 and 0.23 for the two years. Heritability estimates for onset of flowering showed more variation. From parent-offspring regression, the heritabilities were 0.72 and 0.37, and from variance component analysis the estimates were 0.53 and 0.19 for 1993 and 1994, respectively. The obtained heritability values and realized responses suggest that particularly in early selection generations, even with mass selection, considerable progress can be expected. Since correlation studies revealed neither phenotypic nor genotypic correlation between oil content and onset of flowering, selection for both characters can be undertaken independently.     

Breeding for improvement of flowering attributes of winterhardy rosa kordesii Wulff hybrids

Summary The results from tetraploid hybrids of R. kordesii showed that flowering attributes can be improved by a suitable combination of modifying factors as was shown previously by investigations with diploid hybrids from R. rugosa. A longer flowering period than 7 weeks indicated always the ability for recurrent bloom in these investigations but a shorter flowering period did not always indicate non-recurrent bloom.The offspring from the cross of the recurrent R. kordesii with the non-recurrent seedling G12 segregated into non-recurrent and recurrent types in a ratio of 3:1 for a tetrasomic inheritance, assuming a duplex segregation and complete dominance.The flowering attributes could be improved without loss of a high level of winterhardiness.     

Reconstructing Fragaria × ananassa utilizing wild F. virginiana and F. chiloensis: inheritance of winter injury, photoperiod sensitivity, fruit size, female fertility and disease resistance in hybrid progenies

The genetics of disease resistance, winter hardiness, spring bloom date, fruit set, ovule set, fruit size, and photoperiod sensitivity was investigated in crosses between sets of elite selections of F. virginiana and F. chiloensis in Minnesota and Ontario. In Minnesota, family means varied considerably for all traits except ovule set. For all other traits, general combining ability was significant for at least one species, while specific combining ability was significant for only spring bloom date. In Ontario, general combining ability was significant for all traits in at least one species except flower number. Just as they were in previous crosses with F.  × ananassa cultivars, the F. virginiana parents High Falls 22 and Montreal River 10 were notable for producing offspring with large fruit and high fertility. Fragaria chiloensis parents exhibited strong combining ability effects for short day-induced flowering and suppressed the expression of day-neutral flowering in these progeny compared to progeny of these F. virginiana in previous crosses with F. × ananassa. These results indicate that substantial breeding progress can be made by reconstructing F. × ananassa if care is taken to select elite, complementary genotypes of F. virginiana and F. chiloensis.     

QTL identification of yield-related traits and their association with flowering and maturity in soybean

Two soybean recombinant inbred line populations, Jinpumkong 2 × SS2-2 (J × S) and Iksannamulkong × SS2-2 (I x S) showed population-specific quantitative trait loci (QTLs) for days to flowering (DF) and days to maturity (DM) and these were closely correlated within population. In the present study, we identified QTLs for six yield-related traits with simple sequence repeat markers, and biological correlations between flowering traits and yield-related traits. The yield-related traits included plant height (PH), node numbers of main stem (NNMS), pod numbers per plant (PNPP), seed numbers per pod (SNPP), 100-seed weight (SW), and seed yield per plant (SYPP). Eighteen QTLs for six yield-related traits were detected on nine chromosomes (Chrs), containing four QTLs for PH, two for NNMS, two for PNPP, three for SNPP, five for SW, and two for SYPP. Two highly significant QTLs for PH and NNMS were identified on Chr 6 (LG C2) in both populations where the major flowering gene, E1, and two DF and DM QTLs were located. One other PNPP QTL was also located on this region, explaining 12.9% of phenotypic variation. Other QTLs for yield-related traits showed population-specificity. Two significant SYPP QTLs potentially related with QTLs for SNPP and PNPP were found on the same loci of Chrs 8 (Satt390) and 10 (Sat_108). Also, highly significant positive phenotypic correlations (P < 0.01) were found between DF with PH, NNMS, PNPP, and SYPP in both populations, while flowering was negatively correlated with SNPP and SW in the J × S (P < 0.05) and I × S (P < 0.01) populations. Similar results were also shown between DM and yield-related traits, except for one SW. These QTLs identified may be useful for marker-assisted selection by soybean breeders.     

Genetic analysis and associated SRAP markers for flowering traits of chrysanthemum (<Emphasis Type="Italic">Chrysanthemum morifolium</Emphasis>)

The inheritance of two flowering traits of chrysanthemum, initial blooming time and the duration of flowering, was investigated using segregation within an F ₁ population derived from a cross between the autumn-flowering ‘Yuhualuoying’ and the summer-flowering ‘Aoyunhanxiao’ cultivars. The analysis, based on a single segregating generation and the major gene plus polygene mixed inheritance model, showed that the inheritance of both traits was compatible with the presence of two pairs of major genes displaying additivity–dominance–epistasis, with additivity predominating. As the heritability of both pairs of major genes was high (initial blooming time ~65%, duration of flowering ~72%), it should be possible to select for both traits in early breeding generations. A marker-trait association analysis based on sequence-related amplified polymorphism (SRAP) genotyping uncovered 10 (initial blooming time) and 12 (duration of flowering) markers significantly associated with phenotype, cumulatively explaining, respectively, 46 and 54% of the variation. Some potentially useful markers were identified.     

Possibilities of selection for keeping quality in tulip breeding

Summary The vase-life in tulip (Tulipa L.) is an important character. Research was done on the possibilities of selecting for keeping quality. It was found that the keeping quality of undetached flowers was strongly correlated with the keeping quality of cut flowers at 17°C in a glasshouse. The period from flowering date till 50% discoloration appeared to be highly correlated with days to perianth drop. For practical reasons the latter trait has preference in selection work. The number of days to discoloration is also an effective selection criterion. Flower longevity in the field in April/May and in the glasshouse were significantly correlated; thus, already in the field a first selection on keeping quality can be carried out. The increase in height for flowering (adult) and non-flowering (juvenile) plants during forcing did not appear to be significantly correlated with flower longevity, so preselection on this character is not promising. Flower longevity was positively correlated with forcing period. This poses some problems in selection, as a long forcing period is considered an undesirable character. The daily water uptake of cut flowers was significantly correlated with flower longevity.     

Path analysis of the relationships between seed yield and some morphological and phenological traits in safflower (Carthamus tinctorius L.)

Path analysis was performed on plant characters of six safflower genotypes grown in a two year field experiment to determine for seed yield, the direct and indirect effects of the following traits: total biomass, stem yield, number of primary branches/plant, number of secondary branches/plant, number of seeds/m², number of seeds/capitulum, number of capitula/plant, capitulum diameter, 1000-seed weight, seed weight/capitulum, distance between ground level and the first fertile branch, plant height, number of days to the beginning of branching, number of days to the beginning of flowering, number of days to 50% flowering, number of days to full flowering and flowering duration. Seed yield was significantly correlated with the following traits: total biomass, stem yield, capitulum diameter, 1000-seed weight, seed weight/capitulum, distance between ground level and the first fertile branch, number of days to the beginning of branching and flowering duration. Total biomass, seed weight/capitulum, distance between ground level and the first fertile branch, 1000-seed weight and flowering duration had substantial direct effects, in that order, on enhancement of seed yield. The significant positive correlation coefficient of capitulum diameter with seed yield resulted from positive indirect effects of total biomass, seed weight/capitulum and 1000-seed weight. Conversely, the significant negative correlations between number of days to the beginning of branching and distance between ground level and the first fertile branch and seed yield resulted from negative indirect effects of the same three traits. Stepwise multiple regression analysis showed that 94% of the total variation in seed yield could be explained by variation in total biomass and by number of days to the beginning of branching (84 and 10%, respectively). Results suggest that total biomass and number of days to the beginning of branching are primary selection criteria for improving seed yield in safflower.     

Flowering behaviour,male sterility and berry setting in tetraploid Solanum tuberosum germplasm

Summary Six hundred and seventy six accessions of cultivated potato (Solanum tuberosum ssp. tuberosum) from 25 countries, were studied for flowering and fruiting behaviour under long days (12–14 h). Flowering intensity ranged from dropping of floral buds just after initiation to profuse blooming. The majority (58.3%) of the accessions bloomed profusely, though 20.4% of the accessions did not bloom at all. Weeks to flowering ranged from 6 to 15 and the majority (66.5%) of the flowering accessions bloomed within 8 to 9 weeks after planting. Duration of flowering ranged from 1 to 10 weeks and the majority (68.1%) of the flowering accessions bloomed for 1 to 4 weeks only. Twentythree per cent of the flowering accessions were completely male sterile. Maximum male fertility was 90% only. No berry setting was observed in 31.8% of the flowering accessions. Only 54.3 per cent of the accessions were found to be fertile in all respects and could be used both as male and female parents. Premature bud abscission was the major cause of sterility. Peru was the best source of profuse-flowering genotypes, Poland was the best source of early flowering genotypes and Mexico was the best source of long duration flowering and good berry setting genotypes. The results suggested that flower bud formation; the growth and development of mature flowers; weeks to flowering and duration of flowering are independent characters controlled by different genes of quantitative nature. Berry setting and duration of flowering were closely associated (r=0.95). Genetic as well as environmental factors interfered with the developmental process leading to flower production and berry setting at different times in different genotypes. The practical implications of these results for true potato seed production are discussed.Publication No. 1298, CPRI, Shimla.     

5个美国山核桃优良品种开花等性状比较

为解决安徽地区美国山核桃品种少、产量低等问题,连续13年对引种的美国山核桃实生品种对比观察,筛选出‘安农1号’等5个优良适生品种。并对这5个品种的新枝及叶萌发生长节律、雌雄花开花物候、花期长短等特性进行观测分析。结果表明,5个品种新枝平均长度差异达到6.5 cm,叶平均长度差异3.3 cm;枝梢、叶、雄花序生长量最大均为温度最高日期;5个品种雄花盛花期持续时间相差不大;‘安农5号’雌花盛花期持续10天,比其他4个品种长3~5天;‘安农1号’、‘安农3号’、‘安农5号’均为同时型品种,‘安农2号’为雄先型品种,‘安农4号’为雌先型品种。     

Quantitative genetic analysis of flowering time in the Davis Population of gerbera

Summary Phenotypic and genetic correlations of flowering time (FT) with cut-flower yield (Y) were estimated from six generations of the Davis Population of gerbera (Gerbera hybrida, Compositae). The phenotypic correlation was –0.34; the genetic correlation was –0.47 when estimated from ANOVA of a NCII design and –0.72 when estimated from parent-offspring analysis. An indirect selection model was constructed to assess the efficiency of indirect selection for Y using FT as a marker. This model includes population size and generation time as variables because they differ for FT and Y. The results indicate that indirect selection will be more efficient than direct selection.Correlations of FT with flower quality traits, including scape length (SL), flower diameter (FD), scape dry weight (SDW) and flower dry weight (FDW), were also estimated. FT was phenotypically independent of these traits. However, statistically significant estimates of genetic correlation indicate that FT may be correlated with flower quality traits. Thus, indirect selection on FT to increase Y may result in undesirable correlated responses for flower quality.     

Exploitation of the late flowering species <Emphasis Type="Italic">Brassica oleracea</Emphasis> L. for the improvement of earliness in <Emphasis Type="Italic">B. napus</Emphasis> L.: an untraditional approach

The oilseed Brassica rapa flowers and matures earlier than B. oleracea, as well as their amphidiploid B. napus. Therefore, earliness of B. rapa has been investigated as a source of variation for earliness in B. napus breeding programs. Variation for days to flower exists in B. oleracea; however, its earliest flowering variant B. alboglabra flowers 2–3 weeks later than B. napus. We hypothesized that the C genome of B. alboglabra carries alleles for early flowering which are different from the C-genome alleles of B. napus; and these alleles can be used for the improvement of B. napus. To test this, we examined flowering time in pedigree and DH populations from two B. napus × B. alboglabra crosses. A B. napus line with about a week earlier flowering than the B. napus parent was achieved through reconstitution of its C genome following pedigree selection. Introgression of the B. alboglabra allele in the early flowering pedigree lines is also evident from the presence of B. alboglabra-specific SSR alleles in this line. However, application of doubled haploidy failed to generate any line that flowered earlier than the B. napus parent, which is probably due to the difficulty of obtaining large numbers of euploid B. napus DH lines from this interspecific cross. Thus, we demonstrate that a trait of the diploid species, which apparently looks undesirable, might in fact be highly valuable for the improvement of amphidiploids; and knowledge from this research can also be applied for other traits.     

A protocol to avoid precocious flowering of sunflower plantlets in vitro

Precocious flowering in in vitro plantelets of sunflower is one of the unfavourable phenomena when using tissue endure. In this sundy additional evidence is presented on precocious flowering of sunflower regenerats. Three day/night cycles (16/8h. 12/12h and 8/16h) and some modifications of media were investigated. Under standard conditions (16/8h day night. 25C) 62% of the plamlels formed flowers, while 55% formed flowers when grown in 12/12 h day. night at 20C and 31% when plantiets were grown under cultivation conditions of 8/16h day-night ai 20C. According to the results obtained, precocious flowering of sunflower plantlets in tesl tubes depends on culture conditions, nutrition medium and genotype. It was found that 20C and 8/16h diiy/nighl was the most favourable condition to reduce precocious flowering of sunflower planllels in the lest tuhe. Modified nutrition media can also help to reduce in vitro flowering.     

Genome-wide association study of differences in 14 agronomic traits under low- and high-density planting models based on the 660k SNP array for common wheat

One hundred and ninety-seven wheat accessions from Yellow and Huai Winter Wheat Region (YHW) were evaluated for differences of 14 agronomic traits under low- and high-density plantings. Compared with the high-density plantings, plant height, neck length, uppermost internode length, flag leaf angle and number of sterile spikelets under the low-density plantings reduced, while heading date, flowering date, flag leaf length and width, spike length, number of fertile spikelets, grain number per spike, thousand-kernel weight and grain weight per spike increased. A total of 1,118 markers were detected based on GWAS, and seven QTLs were confirmed. One QTL on chromosomes 5BL and two other QTLs on 5Dl were all tightly associated with flowering date difference. Bioinformatics analysis revealed that two haploblocks in 5Dl were involved, and the Vrn-D1 locus was located in this interval. A region on chromosome 5B at around 531.5 Mb was significantly associated with plant height difference. Two QTLs including AX-94840438 (7BL) and AX-94563647 (7DS) were responsible for neck length or uppermost internode length difference.     

Genetic variation in horticulturally important traits of fifteen wild lingonberry Vaccinium vitis-idaea L. populations

Plant breeding of lingonberry (Vaccinium vitis-idaea L.) is still in its infancy. In order to optimize sampling strategy to broaden the genetic base and to improve horticulturally important traits, we need more information about the genetic structure of wild populations. In a field study, seeds were collected from thirteen widely spaced lingonberry populations in Sweden, from one in Estonia and from one in Japan. The resulting seedlings were subsequently transferred into a field with a randomized design and were investigated regarding horticulturally important traits (growth, flowering, phenology and cropping performance). Common for all traits was that the amount of variation (mean for 17 traits: 21.8% ± 11.2) was smaller among populations than within populations. In spite of this low variation, the study revealed significant genetic variation (p<0.05) among populations in nearly all traits investigated. Significant correlations were found between several traits: between plant width and plant height (r=0.516, p<0.001),between plant height and total fruit yield (r=0.253, p<0.001),between number of rhizome-derived daughter plants and total fruit yield (r=–0.189, p<0.001) and between the beginning of spring flowering and the duration of repeat flowering (r=–0.354, p<0.001). Many traits were associated with the latitude of the sample location, e.g. duration of flowering (r=–0.620, p<0.05) and total fruit yield (r=–0.580, p<0.05). Populations collected from southern latitudes (56°–60°N) in general showed better values than the northern populations for horticulturally important traits. The Japanese population, which belongs to the subspecies minus, differed in many traits from all the other populations which belong to the subspecies vitis-idaea. This revised version was published online in July 2006 with corrections to the Cover Date.