Timing Of Bud Set Research Articles

Analysis of expression patterns of candidate genes for bud set and cold tolerance in scots pine (Pinus sylvestris l.)

Conifers, like other perennial plants adapt their growth rhythm to seasonal changes in the environment. Growth cessation and bud set are among the main adaptations used by the plants to prepare for winter. These adaptive traits are mainly controlled by photoperiod, temperature and light quality and show a clinal variation in different species including Scots pine. In conifers, efforts have been made to understand the genetic basis of these traits. In Norway spruce for instance, a Flowering Locus T homolog (PaFT4) has been shown to be implicated in the control of growth rhythm. We previously evaluated genetic variation for timing of bud set and cold tolerance in a large association population of Scots pine (Pinus sylvestris L.) from Punkaharju, Southern Finland, along with five other populations used as control for clinal variation. To correlate this genetic variation with the expression pattern of some candidate genes already described in other species including conifers as involved in the control of bud set (e.g. FT4, PRR1, Gi, Myb) and cold tolerance (e.g. Aba responsive, DHN3, ERD, LEA), the Punkaharju population was used together with two others from Kolari (Northern Finland) and Poland. For photoperiod treatments, seedlings of eight families from each population were grown in a greenhouse under natural photoperiod conditions and in growth chambers under constant light for three months before transfer to three different photoperiod conditions (20 h/4 h, 17 h/7 h and 8 h/16 h light/dark). For cold treatments, the same families were grown in growth chambers under constant light for two and a half months and divided into two parts. The first part was directly submitted to the cold treatments (+4°C for one week followed by -5°C for 48 hours) while for the second part, seedlings were allowed to set buds under short day conditions (8 h light/16 h dark) before treatments. The results of this expression study will be described in relation to the phenotypic variance already observed.

Scanning the genome for gene SNPs related to climate adaptation and estimating selection at the molecular level in boreal black spruce

Outlier detection methods were used to scan the genome of the boreal conifer black spruce (Picea mariana [Mill.] B.S.P.) for gene single-nucleotide polymorphisms (SNPs) potentially involved in adaptations to temperature and precipitation variations. The scan involved 583 SNPs from 313 genes potentially playing adaptive roles. Differentiation estimates among population groups defined following variation in temperature and precipitation were moderately high for adaptive quantitative characters such as the timing of budset or tree height (Q(ST) = 0.189-0.314). Average differentiation estimates for gene SNPs were null, with F(ST) values of 0.005 and 0.006, respectively, among temperature and precipitation population groups. Using two detection approaches, a total of 26 SNPs from 25 genes distributed among 11 of the 12 linkage groups of black spruce were detected as outliers with F(ST) as high as 0.078. Nearly half of the outlier SNPs were located in exons and half of those were nonsynonymous. The functional annotations of genes carrying outlier SNPs and regression analyses between the frequencies of these SNPs and climatic variables supported their implication in adaptive processes. Several genes carrying outlier SNPs belonged to gene families previously found to harbour outlier SNPs in a reproductively isolated but largely sympatric congeneric species, suggesting differential subfunctionalization of gene duplicates. Selection coefficient estimates (S) were moderate but well above the magnitude of drift (>>1/N(e)), indicating that the signature of natural selection could be detected at the nucleotide level despite the recent establishment of these populations during the Holocene.

Gene expression changes during short day induced terminal bud formation in Norway spruce

The molecular basis for terminal bud formation in autumn is not well understood in conifers. By combining suppression subtractive hybridization and monitoring of gene expression by qRT-PCR analysis, we aimed to identify genes involved in photoperiodic control of growth cessation and bud set in Norway spruce. Close to 1400 ESTs were generated and their functional distribution differed between short day (SD-12 h photoperiod) and long day (LD-24 h photoperiod) libraries. Many genes with putative roles in protection against stress appeared differentially regulated under SD and LD, and also differed in transcript levels between 6 and 20 SDs. Of these, PaTFL1(TERMINAL FLOWER LIKE 1) showed strongly increased transcript levels at 6 SDs. PaCCCH(CCCH-TYPE ZINC FINGER) and PaCBF2&3(C-REPEAT BINDING FACTOR 2&3) showed a later response at 20 SDs, with increased and decreased transcript levels, respectively. For rhythmically expressed genes such as CBFs, such differences might represent a phase shift in peak expression, but might also suggest a putative role in response to SD. Multivariate analyses revealed strong differences in gene expression between LD, 6 SD and 20 SD. The robustness of the gene expression patterns was verified in 6 families differing in bud-set timing under natural light with gradually decreasing photoperiod.

Widespread, ecologically relevant genetic markers developed from association mapping of climate‐related traits in Sitka spruce (Picea sitchensis)

• Genecological studies in widespread tree species have revealed steep genetic clines along environmental gradients for climate-related traits. In a changing climate, the ecological and economic importance of conifers necessitates an appraisal of how molecular genetic variation shapes quantitative trait variation, and one of the most promising approaches to answer this question is association mapping. • We phenotyped a wide collection of 410 individuals of the widely distributed conifer Sitka spruce rangewide (Picea sitchensis) for budset timing and autumn cold hardiness, and genotyped these individuals for a panel of 768 single nucleotide polymorphisms (SNPs) representing > 200 expressed nuclear genes. • After correcting for population structure, associations were detected in 28 of the candidate genes, which cumulatively explained 28 and 34% of the phenotypic variance in cold hardiness and budset, respectively. Most notable among the associations were five genes putatively involved in light signal transduction, the key pathway regulating autumn growth cessation in perennials. Many SNPs with phenotypic associations were also correlated with at least one climate variable. • This study represents a significant step toward the goal of characterizing the genomic basis of adaptation to local climate in conifers, and provides an important resource for breeding and conservation genetics in a changing climate.

MicroRNAs, the epigenetic memory and climatic adaptation in Norway spruce

*Norway spruce expresses a temperature-dependent epigenetic memory from the time of embryo development, which thereafter influences the timing bud phenology. MicroRNAs (miRNAs)are endogenous small RNAs, exerting epigenetic gene regulatory impacts. We have tested for their presence and differential expression. *We prepared concatemerized small RNA libraries from seedlings of two full-sib families, originated from seeds developed in a cold and warm environment. One family expressed distinct epigenetic effects while the other not. We used available plant miRNA query sequences to search for conserved miRNAs and from the sequencing we found novel ones; the miRNAs were monitored using relative real time-PCR. *Sequencing identified 24 novel and four conserved miRNAs. Further screening of the conserved miRNAs confirmed the presence of 16 additional miRNAs. Most of the miRNAs were targeted to unknown genes. The expression of seven conserved and nine novel miRNAs showed significant differences in transcript levels in the full-sib family showing distinct epigenetic difference in bud set, but not in the nonresponding full-sib family. Putative miRNA targets were studied. *Norway spruce contains a set of conserved miRNAs as well as a large proportion of novel nonconserved miRNAs. The differentially expression of specific miRNAs indicate their putative participation in the epigenetic regulation.

Tracheid production phenology of Picea mariana and its relationship with climatic fluctuations and bud development using multivariate analysis

Research on cambium phenology in trees and its limiting factors in natural conditions is still at an early stage of development, restricting our capacity to precisely evaluate the effect of growing season length and climate fluctuations on tracheid production. The first objective of this paper was to describe cambial tracheid production phenology of black spruce (Picea mariana (Mills.) BSP). Repeated tree ring sampling was performed from 2002 to 2006 on four sites (48 degrees 13.78' N, 71 degrees 15.18' W; 48 degrees 51.92' N, 70 degrees 20.57' W; 49 degrees 43.92' N, 71 degrees 56.88' W; and 50 degrees 41.78' N, 72 degrees 11.03' W) representative of closed black spruce forest in Quebec, Canada. The timing of cambial initiation and cambial cessation in black spruce differs from year to year, the first occurring on 4 June on average, whereas the second occurs on 15 August. During a single year, these events do not vary significantly in space within the study area. The duration of cambial tracheid production does not vary significantly in either time or space. The second objective of this study was to identify the climatic factors that explain variations in initiation and cessation. Air temperature and humidity, soil temperature and water content, rain precipitations, snow cover as well as photosynthetically active radiation were monitored at each studied site. These were then used to create sets of candidate regressors to explain timing of phenological events. Timing of cambial initiation is primarily dependent on mean temperature between mid-March and initiation itself. Vapor pressure during this period is also important but in a negative way. A significant effect of the previous year's August soil and air temperature conditions suggests a link with spring bud activity resumption, an interpretation that is supported by an analysis significantly linking measured timing of bud break to cambial initiation. Cessation of cambial tracheid production is influenced by factors linked to photosynthesis during the period from mid-July to cessation. Those related to water status, namely saturation vapor pressure, soil water content and vapor pressure are particularly influential, but light intensity and soil temperature also have an effect. Also, because mid-July corresponds to the timing of bud set and because the previous late summer's soil temperature has a significant effect, a clear link is established with apical cessation.

Alteration of PHYA expression change circadian rhythms and timing of bud set in Populus

In many temperate woody species, dormancy is induced by short photoperiods. Earlier studies have shown that the photoreceptor phytochrome A (phyA) promotes growth. Specifically, Populus plants that over-express the oat PHYA gene (oatPHYAox) show daylength-independent growth and do not become dormant. However, we show that oatPHYAox plants could be induced to set bud and become cold hardy by exposure to a shorter, non-24 h diurnal cycle that significantly alters the relative position between endogenous rhythms and perceived light/dark cycles. Furthermore, we describe studies in which the expression of endogenous Populus tremula x P. tremuloides PHYTOCHROME A (PttPHYA) was reduced in Populus trees by antisense inhibition. The antisense plants showed altered photoperiodic requirements, resulting in earlier growth cessation and bud formation in response to daylength shortening, an effect that was explained by an altered innate period that leads to phase changes of clock-associated genes such as PttCO2. Moreover, gene expression studies following far-red light pulses show a phyA-mediated repression of PttLHY1 and an induction of PttFKF1 and PttFT. We conclude that the level of PttPHYA expression strongly influences seasonally regulated growth in Populus and is central to co-ordination between internal clock-regulated rhythms and external light/dark cycles through its dual effect on the pace of clock rhythms and in light signaling.

Local adaptation at the range peripheries of Sitka spruce

High-dispersal rates in heterogeneous environments and historical rapid range expansion can hamper local adaptation; however, we often see clinal variation in high-dispersal tree species. To understand the mechanisms of the species' distribution, we investigated local adaptation and adaptive plasticity in a range-wide context in Sitka spruce, a wind-pollinated tree species that has recently expanded its range after glaciations. Phenotypic traits were observed using growth chamber experiments that mimicked temperature and photoperiodic regimes from the limits of the species realized niche. Bud phenology exhibited parallel reaction norms among populations; however, putatively adaptive plasticity and strong divergent selection were seen in bud burst and bud set timing respectively. Natural selection appears to have favoured genotypes that maximize growth rate during available frost-free periods in each environment. We conclude that Sitka spruce has developed local adaptation and adaptive plasticity throughout its range in response to current climatic conditions despite generally high pollen flow and recent range expansion.

Rapid change in adaptive performance from one generation to the next in Picea abies—Central European trees in a Nordic environment

Seedlings of open-pollinated Picea abies families from Norwegian and Central European parent trees standing at three sites in Norway were tested for timing of bud set at the end of the first growth season together with seedlings from control provenances producing seeds at their geographical origin. The parental origins were confirmed with a maternally inherited mitochondrial marker that distinguishes trees of the Northern European range from those of the Central European range. The seedlings from the families of Central European mother trees producing seeds in Norway had on average a bud set more similar to the families of local Norwegian origin producing seeds at the same site than the provenance of the same Central European origin. It is argued that the rapid change in this adaptive trait from one generation to the next can be explained by recent research results demonstrating that day length and temperature conditions during embryo formation and maturation can influence the phenotypic performance of seedlings in Norway spruce. This effect may influence the fitness of naturally regenerated plants produced in plantations of Central European trees in Norway.

Seedling cold hardiness, bud set, and bud break in nine provenances of Pinus greggii Engelm.

Cold hardiness and timing of bud set and bud break are important processes that provide protection of nursery seedlings against low temperatures. Seedlings of 9 provenances of Pinus greggii from two different regions of Mexico were tested to determine cold hardiness, bud set, and bud break timing differences. Needle sections were exposed to freezing temperatures to determine an injury index of each provenance. In addition, bud set and bud break timing were recorded through the fall, winter and spring. There were significant differences in cold hardiness between seedlings from northern and southern provenances. At the maximum cold hardiness, the index of injury (LT 50) for northern provenances was LT 50 = −18 °C, compared to −12 °C for southern provenances. There was a considerable variation among the provenances in the proportion of seedlings that set terminal buds. Seedlings from northern provenances had greater proportions of seedlings that set a terminal bud than seedlings from southern provenances. There were also significant differences in the bud break timing in the following spring among the 9 provenances. Seedlings from northern provenances broke bud earlier than southern provenances. Cold hardiness, bud set, and bud break timing results may be useful to determine how far a specific seed source can be moved from its natural environment.

Nucleotide polymorphism and phenotypic associations within and around the phytochrome B2 Locus in European aspen (Populus tremula, Salicaceae).

We investigated the utility of association mapping to dissect the genetic basis of naturally occurring variation in bud phenology in European aspen (Populus tremula). With this aim, we surveyed nucleotide polymorphism in 13 fragments spanning an 80-kb region surrounding the phytochrome B2 (phyB2) locus. Although polymorphism varies substantially across the phyB2 region, we detected no signs for deviations from neutral expectations. We also identified a total of 41 single nucleotide polymorphisms (SNPs) that were subsequently scored in a mapping population consisting of 120 trees. We identified two nonsynonymous SNPs in the phytochrome B2 gene that were independently associated with variation in the timing of bud set and that explained between 1.5 and 5% of the observed phenotypic variation in bud set. Earlier studies have shown that the frequencies of both these SNPs vary clinally with latitude. Linkage disequilibrium across the region was low, suggesting that the SNPs we identified are strong candidates for being causally linked to variation in bud set in our mapping populations. One of the SNPs (T608N) is located in the "hinge region," close to the chromophore binding site of the phyB2 protein. The other SNP (L1078P) is located in a region supposed to mediate downstream signaling from the phyB2 locus. The lack of population structure, combined with low levels of linkage disequilibrium, suggests that association mapping is a fruitful method for dissecting naturally occurring variation in Populus tremula.

Timing of bud set in Picea abies is regulated by a memory of temperature during zygotic and somatic embryogenesis

It has been shown previously that height growth and bud phenology are influenced by the temperature during zygotic embryogenesis in Picea abies. To test whether this phenomenon operates within individual plants, clones produced through somatic embryogenesis were used. Seeds were from a full-sib family produced in both a cold (outdoor) and a warm (inside a glasshouse) environment. Embryogenic clones derived from mature zygotic embryos from both crossing environments were cultured at 18, 23 and 28 degrees C during the proliferation and embryo maturation steps. After the second growing season in a glasshouse, plants from the warm seed production environment were taller and had significantly later bud set. For the first time, it is also shown that plants are influenced by the in vitro temperature during somatic embryo development. The warmer the temperature, the later the plants formed terminal buds. The differences were similar to those produced by a provenance separation of 4-6 degrees of latitude. The results indicate that there exists a mechanism in P. abies that operates during embryo development and adjusts the timing of bud set in accordance with the temperature conditions in which the mother tree lives. This in turn counteracts negative effects of gene flow among populations located along altitudinal and latitudinal gradients.

Genetic variation of growth rhythm traits in the limits of a latitudinal cline in Scots pine

Scots pine ( Pinus sylvestris L.) has the widest distribution of pine species and the populations are locally adapted to very different environmental conditions. Adaptive traits such as those related to growth are optimal for understanding adaptation of populations to local conditions in widely distributed forest species. A study of the timing of growth during the first growing period of families in four populations from the latitudinal limits of the distribution range was conducted. Individual growth curves were fitted, and a set of variables related to growth rhythm and timing of budset was obtained for genetic analyses. Pooled heritabilities across populations were very high for most of the traits (0.43–1.09), and population differentiation for growth variables showed high values as well (QST= 0.19–0.71). Phenotypic correlations were higher than genetic ones, and most of them were positives. Even no general patterns of additive variances were found, the high additive genetic variance obtained (14% ± 8%, mean ± SE) suggests that additive genetic variance is not the limiting factor for adaptation to a new optimum within much of the range for these traits. Changes in means, additive genetic variances, and additive genetic coefficient of variation by population are also discussed.

Comparing Bayesian estimates of genetic differentiation of molecular markers and quantitative traits: an application to Pinus sylvestris

Comparison of the level of differentiation at neutral molecular markers (estimated as F(ST) or G(ST)) with the level of differentiation at quantitative traits (estimated as Q(ST)) has become a standard tool for inferring that there is differential selection between populations. We estimated Q(ST) of timing of bud set from a latitudinal cline of Pinus sylvestris with a Bayesian hierarchical variance component method utilizing the information on the pre-estimated population structure from neutral molecular markers. Unfortunately, the between-family variances differed substantially between populations that resulted in a bimodal posterior of Q(ST) that could not be compared in any sensible way with the unimodal posterior of the microsatellite F(ST). In order to avoid publishing studies with flawed Q(ST) estimates, we recommend that future studies should present heritability estimates for each trait and population. Moreover, to detect variance heterogeneity in frequentist methods (ANOVA and REML), it is of essential importance to check also that the residuals are normally distributed and do not follow any systematically deviating trends.

CO 2 enrichment, nitrogen fertilization and development of freezing tolerance in Norway spruce

Plant growth and adaptation to cold and freezing temperatures in a CO2-enriched atmosphere have received little attention despite the predicted effects of elevated CO2 on plant distribution and productivity. Norway spruce [Picea abies (L.) Karst.] seedlings from latitudinally distinct seed sources (66°N and 60°N) were grown for one simulated growth season under controlled conditions in an atmosphere enriched in CO2 (70 Pa) and at ambient CO2 (40 Pa), combined factorially with low (3.6 mM) or high (15.7 mM) concentrations of nitrogen fertilization. There was a clear difference between the two provenances in height growth, in the timing of bud set, and in freezing tolerance. Nitrogen fertilization increased height growth in both provenances, while CO2 enrichment stimulated height growth only in the southern provenance. We found no significant effects of elevated CO2 or nitrogen fertilization on the timing of bud set. During cold acclimation, freezing tolerance increased from −10°C to −35°C, and there was a marked increase in all soluble sugars except inositol. Elevated CO2 in combination with high nitrogen led to a slight increased freezing tolerance in both provenances during the early stages of cold acclimation. However, towards the end of cold acclimation, elevated CO2 and high nitrogen led to reduced freezing tolerance in the southern provenance, while elevated CO2 and low nitrogen reduced freezing tolerance in the northern provenance. These results suggest that CO2 enrichment influences the development of freezing tolerance, and that these responses differ with available nitrogen and between provenances.

Molecular genetic analysis of dormancy-related traits in poplars

Abstract We studied the molecular genetics of dormancy-related traits in an F2 family of poplar (Populus) hybrids derived from a cross between a northern genotype of black cottonwood and a southern genotype of eastern cottonwood by mapping quantitative trait loci (QTLs) and candidate genes. Dormancy-related traits included timing of vegetative bud set, fall frost damage, chilling response, timing of vegetative bud flush, and winter survival under field conditions, as well as photoperiodic responses (timing of bud set and number of new leaves) in a warm greenhouse under either a uniform 8-h photoperiod or a naturally shortening photoperiod in the fall. QTL analyses were conducted using a linkage map consisting of AFLP, microsatellite, and candidate gene markers. The candidate genes were chosen because of their potential roles in either photoperiodic perception (PHYB1, PHYB2) or abscisic acid signal transduction (ABI1B, ABI1D, ABI3). Significant QTLs were detected for all dormancy-related traits, except for...

Genetic selection for cold hardiness in coastal Douglas-fir seedlings and saplings

Genetic control of cold hardiness in two-year-old seedlings was compared with that in 7-year-old saplings of 40 open-pollinated families in each of two breeding populations (Coast and Cascade) of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) from western Oregon. In addition, the efficacy of bud phenology traits as predictors of cold hardiness at the two stages was explored. Fall and spring cold hardiness were assessed using artificial freeze testing. Similar genetic control of cold hardiness in seedlings and saplings is suggested by strong type-B genetic correlations (rB) between the two ages for fall and spring cold injury traits (rB[Formula: see text] 0.78) and by similar trends in individual tree heritability estimates (hi2), e.g., hi2was greater in spring (h–i2= 0.73) than in fall (h–i2= 0.36) and greater in the Coast population (h–i2= 0.69) than in the Cascade population (h–i2= 0.40) at both ages. Strong responses to direct selection are expected for spring cold hardiness at both ages and for fall cold hardiness in seedlings, even under mild selection intensities. Similar heritabilities in seedlings and saplings, and strong genetic correlations between ages for cold-hardiness traits, ensure that selection at one age will produce similar gains at the other age. Type-A genetic correlations (rA) between fall and spring cold hardiness were near zero in the Cascade population (rA= 0.08 and -0.14 at ages 2 and 7, respectively) but were moderate and negative in the Coast population (rA= -0.54 and -0.36, respectively). Bud-burst timing appears to be a suitable surrogate to artificial freeze testing for assessing spring cold hardiness in both seedlings and saplings, as is bud set timing for assessing fall cold hardiness in seedlings, but bud set timing is a poor predictor of fall cold hardiness in saplings.

Quantitative genetics of bud phenology, frost damage, and winter survival in an F2 family of hybrid poplars

We studied the quantitative genetics of bud phenology, fall frost damage, and winter survival in an F2 family (no. 822) of Populus hybrids derived from a cross between two full-sub F1 hybrids (P. trichocarpa (Torr. & Gray×P. deltoides Bartr.). Field traits studied included the timing of bud set (BSF) in Minnesota and Oregon, the timing of bud flush (BFF) in Oregon, as well as fall frost damage (FDF) and winter survival (WSF) in Minnesota. We conclude that Family 822 has substantial genetic variability for all field traits, BSF and BFF are under moderate to strong genetic control (H 2 i =0.48–0.80), FDF and WSF are under low to moderate genetic control (H 2 i =0.27–0.40), and late bud set is associated with increased frost damage and decreased winter survival. In a warm greenhouse, we measured the timing of bud set and the number of new leaves on trees growing under either an 8-h photoperiod (BSSD and NLSD) or a natural photoperiod (NP) from August to December (BSNP and NLNP). We found that BSSD, NLSD, and NLNP are under moderate genetic control (H 2 i =0.53–0.70), but the heritability of BSNP could not be determined because few trees set bud in the warm greenhouse under the NP. By comparing results from the greenhouse experiments with results from the field, we conclude that the genetic correlation between BSSD and BSF (0.53–0.60) is relatively modest and that NPs in the fall are relatively ineffective at promoting bud set under warm greenhouse temperatures, although bud set readily occurred in the field. Although, low levels of light pollution in the greenhouse might have affected BSNP, results from both greenhouse and field experiments suggest that genetic differences in photoperiodic responses play a modest role in explaining genetic differences in the timing of bud set under natural field conditions. Therefore, genetic differences in responses to other environmental factors, such as temperature, deserve greater attention.

An interregional validation of ECOPHYS, a growth process model of juvenile poplar clones.

Field data from poplar plantations in Michigan, Washington, and Wisconsin were used to validate ECOPHYS, a whole-tree growth process model for juvenile poplar. Five clones representing a range of morphological, phenological, and physiological characteristics were planted on the same date at the three sites. Height and diameter measurements were made monthly on 20 trees per clone, and intensive morphological measurements were made every two weeks on two trees per clone. Hourly solar radiation and temperature data were recorded at each site over the growing season. The model was run for each clone x site combination with the weather data and clonal parameters as inputs. A repeated measures ANOVA indicated that there were significant differences in height growth patterns among both clones and sites, as well as significant clone x site interactions. The model generally predicted height growth within a standard deviation of the field plantation means; three of the 15 clone x site simulations were significantly different from the plantation means. The median error between predicted and observed values was 5%. Evaluation of the clonal parameters showed that differences in photosynthetic rates, morphological attributes such as specific leaf area, and timing of budset are primary factors leading to differences in growth.

Effects of plus tree selection and seed orchard environment on progenies of Piceaabies

Open-pollinated progenies from selected plus trees of Piceaabies (L.) Karst., and from average performing trees (controls) in each of five northern (65–66°N) natural stands in Norway, were tested for growth, timing of bud set, and autumn frost hardiness during the first growing season. The plus trees had also been grafted in a southern seed orchard, Lyngdal (58°N). Crosses were performed in the orchard, using orchard pollen from the same plus trees. All progenies were grown in a common test. There were no differences between natural stand progenies from plus tree and from control stand trees, but the plus tree progenies were different from their seed orchard half-sibs. The seed orchard progenies were slightly taller, formed terminal buds later and were more damaged by frost in a freezing test than their northern half-sibs. Except for one mother, seeds were heavier when produced in the southern seed orchard, but the heavier seeds could not explain the more southern-like performance of the seed orchard progenies. The results are discussed in relation to a hypothesis that the non-native southern seed orchard environment affects the progenies, leading to a more southern phenotypic performance than expected.