Fall Cold Research Articles

Stratification Breakdown by Fall Cold Front Winds over the Louisiana Shelf in the Northern Gulf of Mexico: A Numerical Experiment

Cold fronts are meteorological phenomena that impact the northern Gulf of Mexico, mostly between the fall and spring seasons. On average, they pass the region every 3–7 days, with a duration ranging between 24 and 74 h. In the present study, a high-resolution FVCOM model with an unstructured mesh was used to simulate the effect of the fall cold front winds on water column mixing over the Louisiana shelf, which is often stratified in the summer, leading to hypoxia. Numerical experiments were conducted for October 2009, a period with five consecutive cold front events. Winds from an offshore station forced the model, while climatological temperature/salinity profiles prepared by NOAA for September were used for model initialization. The model performance was evaluated by comparing it with the surface current measurements at two offshore stations, and the results showed a good agreement between the model results and observations. Shelf mixing and stratification were investigated through examining the simulated sea surface temperature as well as the longitudinal and cross-shelf vertical sections. Simulation results showed a significant effect on shelf mixing, with the mixed layer depth increasing from the initial values of 5 m to 25 m at the end of simulation at different parts of the shelf, with maximum mixed layer depths corresponding to the peak of cold fronts. The buoyancy frequency, Richardson number, and the average potential energy demand (APED) for mixing the water column were used to quantify the stratification at two selected locations over the shelf. Results showed that all these parameters almost continuously decreased due to mixing induced by cold front wind events during this time. At the station off the Terrebonne Bay with a water depth of 20 m, the water column became fully mixed after three of the cold front events, with Richardson numbers smaller than 0.25 and approaching zero. This continued mixing trend was also proven by obtaining a decreasing trend of APED from 100 to 5 kg/m.s2 with several close to zero energy demand values.

How fall dormancy benefits alfalfa winter-survival? Physiologic and transcriptomic analyses of dormancy process

BackgroundFall dormancy and freezing tolerance characterized as two important phenotypic traits, have great effects on productivity and persistence of alfalfa (Medicago sativa L.). Despite the fact that one of the most limiting traits for alfalfa freezing tolerance in winter is fall dormancy, the interplay between fall dormancy and cold acclimation processes of alfalfa remains largely unknown. We compared the plant regrowth, winter survival, raffinose and amino acids accumulation, and genome-wide differentially expressed genes of fall-dormant cultivar with non-dormant cultivar under cold acclimation.ResultsAveraged over both years, the non-dormant alfalfa exhibited largely rapid regrowth compared with fall dormant alfalfa after last cutting in autumn, but the winter survival rate of fall dormant alfalfa was about 34-fold higher than that of non-dormant alfalfa. The accumulation of raffinose and amino acids were significantly increased in fall dormant alfalfa, whereas were decreased in non-dormant alfalfa under cold acclimation. Expressions of candidate genes encoding raffinose biosynthesis genes were highly up-regulated in fall dormant alfalfa, but down-regulated in non-dormant alfalfa under cold acclimation. In fall dormant alfalfa, there was a significantly down-regulated expression of candidate genes encoding the glutamine synthase, which is indirectly involved in the proline metabolism. A total of eight significantly differentially expressed transcription factors (TFs) related to CBF and ABRE-BFs were identified. The most up-regulated TFs in fall dormant alfalfa cultivar were ABF4 and DREB1C.ConclusionsFall dormant alfalfa drastically increased raffinose and amino acids accumulation under cold acclimation. Raffinose-associated and amino acid-associated genes involved in metabolic pathways were more highly expressed in fall dormant alfalfa than non-dormant alfalfa under cold acclimation. This global survey of transcriptome profiles provides new insights into the interplay between fall dormancy and cold acclimation in alfalfa.

Comparison of cold hardiness in the leaves of various grape cultivars based on photochemical reflectance index

We compared cold hardiness in the leaves of 12 grape cultivars, including two wild species, two Vitis vinifera × V. labrusca , three HPDs (interspecific crosses) and five V. vinifera L. cultivars using PRI -T curves and analysis of variance (ANOVA). The photochemical reflectance index ( PRI ) of most grape leaves decreased linearly when frozen progressively in darkness, but these patterns varied. The PRI of diploid cultivars and blanc cultivars at the standard temperature ( PRI 4°C) remained relatively steady during exposure to successively lower temperatures (0, -2, -4 and -6°C) compared with polyploid and noir cultivars, representing a boundary dividing grape cultivars into frost tolerant and vulnerable. According to this principle, which was tested by ANOVA, the cold hardiness of the four species was ranked (from high to low) as V. vinifera L. > HPD = wild species > V. vinifera × V. labrusca . The cold hardiness of the 12 cultivars was divided into three classes: Resistant: PRI increased markedly compared with the control, R PRI (( PRI - PRI control )/ PRI control ) > 0 (p < 0.05), indicating high freezing tolerance and wide temperature adaption; Tolerant: PRI changed little compared with the control (p < 0.05), R PRI trended to 0, indicating relative stability when exposed to a short period of freezing temperatures; Vulnerable: PRI decreased dramatically compared with the control, R PRI < 0 (p < 0.05), indicating that photosynthesis was inhibited or damaged due to freezing. We also observed seasonal differences in the cold hardiness of the cultivars; grape leaves were more vulnerable to cold in fall than in spring. This study provides a practical method for estimating cold hardiness in grape.

ANALYSIS OF COLD ACCLIMATIZATION IN TWO ASPARAGUS CULTIVARS WITH VARYING PATTERNS OF FALL SENESCENCE

Adequate winter hardiness is paramount for optimal performance of Asparagus officinalis L. cultivars in Southern Ontario, Canada, and may be influenced by fall senescence. Cultivar 'Guelph Millennium' (GM) turns yellow by mid-October prior to 'Jersey Giant' (JG), which will often 'freeze green'. Timely fall senescence may contribute to freezing tolerance and result in the enhanced stand longevity and yield observed for GM compared to JG. In order to understand the relationship between fall senescence and cold acclimation, a field experiment was conducted to assess phenological parameters in plant tissues through the late summer and fall. Once photoperiod and night temperature decreased below 12 h and 10°C, respectively, both cultivars showed increased storage root LT50 values as well as carbohydrate, nitrogen and proline concentrations, while fern chlorophyll and crown water concentrations decreased. Cultivar differences were found for some traits; GM initiated nitrogen and proline accumulation in the roots and chlorophyll catabolism in the fern two weeks prior to JG. Freezing tolerance of storage roots, however, was not significantly different between cultivars. LT50 values were correlated with carbohydrate concentrations and percent water, but not chlorophyll concentration or percent nitrogen. A greater percent of storage roots nitrogen in GM than JG through the fall could help explain the stand longevity of GM.

The mode of gas accretion on to star-forming galaxies

It is argued that galaxies like ours sustain their star formation by transferring gas from an extensive corona to the star-forming disc. The transfer is effected by the galactic fountain -- cool clouds that are shot up from the plane to kiloparsec heights above the plane. The Kelvin-Helmholtz instability strips gas from these clouds. If the pressure and the the metallicity of the corona are high enough, the stripped gas causes a similar mass of coronal gas to condense in the cloud's wake. Hydrodynamical simulations of cloud-corona interaction are presented. These confirm the existence of a critical ablation rate above which the corona is condensed, and imply that for the likely parameters of the Galactic corona this rate lies near the actual ablation rate of clouds. In external galaxies trails of HI behind individual clouds will not be detectable, although the integrated emission from all such trails should be significant. Parts of the trails of the clouds that make up the Galaxy's fountain should be observable and may account for features in targeted 21-cm observations of individual high-velocity clouds and surveys of Galactic HI emission. Taken in conjunction with the known decline in the availability of cold infall with increasing cosmic time and halo mass, the proposed mechanism offers a promising explanation of the division of galaxies between the blue cloud to the red sequence in the colour-luminosity plane.

Association genetics of coastal Douglas fir (Pseudotsuga menziesii var. menziesii, Pinaceae). I. Cold-hardiness related traits.

Adaptation to cold is one of the greatest challenges to forest trees. This process is highly synchronized with environmental cues relating to photoperiod and temperature. Here, we use a candidate gene-based approach to search for genetic associations between 384 single-nucleotide polymorphism (SNP) markers from 117 candidate genes and 21 cold-hardiness related traits. A general linear model approach, including population structure estimates as covariates, was implemented for each marker-trait pair. We discovered 30 highly significant genetic associations [false discovery rate (FDR) Q < 0.10] across 12 candidate genes and 10 of the 21 traits. We also detected a set of 7 markers that had elevated levels of differentiation between sampling sites situated across the Cascade crest in northeastern Washington. Marker effects were small (r(2) < 0.05) and within the range of those published previously for forest trees. The derived SNP allele, as measured by a comparison to a recently diverged sister species, typically affected the phenotype in a way consistent with cold hardiness. The majority of markers were characterized as having largely nonadditive modes of gene action, especially underdominance in the case of cold-tolerance related phenotypes. We place these results in the context of trade-offs between the abilities to grow longer and to avoid fall cold damage, as well as putative epigenetic effects. These associations provide insight into the genetic components of complex traits in coastal Douglas fir, as well as highlight the need for landscape genetic approaches to the detection of adaptive genetic diversity.

Profiling the repertoire of phenotypes influenced by environmental cues that occur during asexual reproduction

The aphid Acyrthosiphon pisum population is composed of different morphs, such as winged and wingless parthenogens, males, and sexual females. The combined effect of reduced photoperiodicity and cold in fall triggers the apparition of sexual morphs. In contrast they reproduce asexually in spring and summer. In our current study, we provide evidence that clonal individuals display phenotypic variability within asexual morph categories. We describe that clones sharing the same morphological features, which arose from the same founder mother, constitute a repertoire of variants with distinct behavioral and physiological traits. Our results suggest that the prevailing environmental conditions influence the recruitment of adaptive phenotypes from a cohort of clonal individuals exhibiting considerable molecular diversity. However, we observed that the variability might be reduced or enhanced by external factors, but is never abolished in accordance with a model of stochastically produced phenotypes. This overall mechanism allows the renewal of colonies from a few adapted individuals that survive drastic episodic changes in a fluctuating environment.

How Cold Can You Go? Frost and Winter Protection for Grape

Although the inland Pacific Northwest has a warm climate during the growing season, grapes grown in this region may be exposed to colder than optimal temperatures at several times during the year. In addition to damage from spring and fall frosts, intermittent winters with little to no snow cover and subzero temperatures can cause vine dieback and death. Temperature patterns in the recent past indicate that both fall and midwinter are times when risk of bud damage from cold events is probable, making proper site selection and cultivar choice critical. Water is not used for frost protection in this climate, but wind machines have proven to be useful. In frost-prone sites, annual sucker growth with cane burying is practiced as an insurance strategy. Modifying pruning strategies has not been shown to be advantageous after fall cold events. If rootstocks are used, research has shown greater scion survival with higher graft positions.

Adaptive variation in fall cold hardiness of aspen from northwestern Ontario

We investigated adaptive variation in fall cold hardiness development based on the electrical conductivity of tissue diffusates (EC) among 20 aspen provenances from northwestern Ontario. Provenance accounted for over 40% of the total variation in cold injury for seven dates from September through November in three provenance trials. Principal component analysis was performed to summarize the combinations of results for all sampling sites, dates and temperatures (traits). Principal component (PC)-1 represented fully developed cold hardiness differences among provenances; PC-2 represented differences in the timing of the onset of cold hardiness development; and PC-3 represented a site-related difference in cold hardiness development. Heat sum in early summer and late summer precipitation together were the best predictors of absolute degree of cold hardiness (PC-1), whereas temperatures for mid- to late summer were best for predicting onset of cold hardiness development (PC-2). In a second study, we assessed the efficacy of chlorophyll fluorescence (CF) as a simpler technique for determining the cold hardiness of aspen stem samples. Fall cold hardiness of stem samples of 12 of the original 20 provenances was estimated by CF, and the results were evaluated by a visual scoring (VS) method. Correlations between EC and CF measurements from the two studies were moderately strong based on the extent of cold hardiness in October of each year, but were negative for September dates because of a later onset of cold hardiness in the EC study year. Although the EC and CF methods gave similar cold hardiness values for stem samples from 12 provenances, the CF method may be preferred to the EC or VS method for species with chlorophyllous stems because of its greater ease of use.

Influence of Late‐Season Iron, Nitrogen, and Seaweed Extract on Fall Color Retention and Cold Tolerance of Four Bermudagrass Cultivars

Influence of Late‐Season Iron, Nitrogen, and Seaweed Extract on Fall Color Retention and Cold Tolerance of Four Bermudagrass Cultivars

Genetic variation in fall cold hardiness in coastal Douglas-fir in western Oregon and Washington

Genetic variation in fall cold damage in coastal Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. menziesii ) was measured by exposing excised branches of seedlings from 666 source locations grown in a common garden to freezing temperatures in a programmable freezer. Considerable variation was found among populations in fall cold hardiness of stems, needles, and buds compared with bud burst, bud set, and biomass growth after 2 years. Variation in fall cold hardiness was strongly correlated (r = 0.67) with cold-season temperatures of the source environment. Large population differences corresponding with environmental gradients are evidence that natural selection has been important in determining genetic variation in fall cold hardiness, much more so than in traits of bud burst (a surrogate for spring cold hardiness), bud set, and growth. Seed movement guidelines and breeding zones may be more restrictive when considering genetic variation in fall cold hardiness compared with growth, phenology, or spring cold hardiness. A regional stratification system based on ecoregions with latitudinal and elevational divisions, and roughly corresponding with breeding zones used in Oregon and Washington, appeared to be adequate for minimizing population differences within regions for growth and phenology, but perhaps not fall cold hardiness. Although cold hardiness varied among populations, within-population and within-region variation is sufficiently large that responses to natural or artificial selection may be readily achieved.

Geographic and seasonal variation in cold hardiness of whitebark pine

Artificial freeze-testing utilizing the electrolyte-leakage method was used to test the cold hardiness of 2-year-old whitebark pine (Pinus albicaulis Engelm.) seedlings growing in a common garden. Testing across all seasons was used to determine the annual pattern of cold hardiness, and more intensive sampling in the fall and spring was used to assess genetic variation in cold injury among geographic regions spanning the range of the species. Mean hardiness varied widely from –9 °C in early summer to below –70 °C in the winter. Trees from interior and northern regions were the most hardy in the fall, while trees from California were the least hardy. Geographic patterns of hardiness in the spring were reversed. Significant differences in cold injury among regions were detected on all dates except during the winter. Heritability was low to moderate for both the spring (h2 = 0.18) and the fall (h2 = 0.28), and genetic correlation was weak (rA = 0.18). Only spring cold injury was genetically correlated with date of needle flush (rA = 0.34). Mean cold injury in the fall was most closely correlated with mean temperature of the coldest month in the parental environment (r = 0.81). Whitebark pine is well adapted to the low temperatures of the harsh environments where it is found; however, regional variation indicates that moving seed for restoration purposes from areas with higher winter temperatures to colder environments may increase the chance of fall cold injury.

Shepherdesses Watching a Flight of Wild Geese

Sheep graze along a plain in twilight quiet, Their earthward heads cropping dark clumps of grass, And near them, by a hedge where yellow leaves Grow golden in the evening’s mellowed air, Bent over yarn and needles knitting wool From these same sheep for mittens -- two young girls. Then suddenly one rises, shades her eyes And gestures to the other not to move, One arm crooked and one stretched out like the V’s Of geese intent on their archaic way Beyond the late fall cold toward Galilee. The...

On the origin of the galaxy luminosity function

Evidence is summarized which suggests that when a protogalaxy collapses, a fraction ƒ of its gas fails to heat to the virial temperature, where ƒ is large for haloes less massive than the value M* associated with L* galaxies. Stars and galaxies form only from the cool gas fraction. Hot gas is ejected from low-mass systems as in conventional semi-analytic models of galaxy formation. In high-mass systems it is retained but does not cool and form stars. Instead it builds up as a largely inert atmosphere, in which cooling is inhibited by an episodically active galactic nucleus. Cold gas frequently falls into galactic haloes. In the absence of a dense atmosphere of virial-temperature gas it builds up on nearly circular orbits and can be observed in the 21-cm line of H i. When there is a sufficiently dense hot atmosphere, cold infalling gas tends to be ablated and absorbed by the hot atmosphere before it can form stars. The picture nicely explains away the surfeit of high-luminosity galaxies that has recently plagued semi-analytic models of galaxy formation, replacing them by systems of moderate luminosity from old stars and large X-ray luminosities from hot gas.

Quantitative genetics of spring and fall cold hardiness in seedlings from two Oregon populations of coastal Douglas-fir

Abstract Genetics of fall and spring cold hardiness were investigated in two western Oregon breeding populations (Coast and Cascade mountains) of Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco). Seedlings from 40 open-pollinated families from each population were grown in raised nursery beds and subjected to two soil-moisture regimes (well-watered and mild drought) to evaluate the influence of summer drought on ranking of families for cold hardiness. Artificial freeze testing (AFT) of detached shoots, followed by visual scoring of injury, was used to evaluate needle, stem and bud cold hardiness on three dates in the fall (September, October and November) after the second growing season, and once in the following spring (March). The Cascade population suffered significantly less cold injury than the Coast population in fall AFT. However, in spring AFT the Cascade population was less cold hardy, although population differences were seldom significant. Families within both breeding zones varied significantly in cold hardiness, with mean estimates of individual heritabilities greater in spring ( h i 2 =0.57) than fall ( h i 2 =0.37) , greater in the Coast ( h i 2 =0.52) than in the Cascade ( h i 2 =0.42) population, and greater in the wet ( h i 2 =0.54) than in the dry moisture regime ( h i 2 =0.40) (fall means based on October tests). A single test date seems adequate to assess fall cold hardiness, because estimated genetic correlations for cold injury between fall test dates were strong ( r A =0.80) . Genetic correlations between spring and fall cold injury, however, were moderately negative ( r B =−0.66 and −0.21, Coast and Cascade, respectively), indicating that cold hardiness needs to be managed as two traits (i.e. fall and spring cold hardiness). Selection for cold hardiness based on a single shoot tissue is expected to increase cold hardiness in the other tissues as well, because genetic correlations between tissues in cold injury were moderately-to-strongly positive in both fall ( r B =0.67) and spring ( r B =0.84) . Seedlings grown under summer drought incurred significantly less cold injury in the fall than those that were well-watered; nevertheless, strong genetic correlations in fall cold injury between moisture regimes ( r B =0.91) indicate that summer moisture conditions had little influence on family rankings for fall cold hardiness. Correlations of injury resulting from a natural frost event in November of the first year with injury from AFT in the fall of the second year ( r A =0.72 and 0.78 for needle and bud injury, respectively) confirmed that AFT reliably predicts cold hardiness to natural frost events.

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.

Genetics of cold hardiness in a cloned full-sib family of coastal Douglas-fir

Variation in cold-hardiness traits, and their extent of genetic control and interrelationships, were investigated among individuals (clones) within a single large full-sib family of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) from Oregon. Cold injury to needle, stem, and bud tissues was evaluated in fall 1996 and spring 1997 following artificial freeze testing of detached shoots collected from 4-year-old ramets (rooted cuttings). Variation among clones in cold-injury scores was significant (p &lt; 0.01) for all shoot tissues in both fall and spring and averaged about three times the magnitude previously observed among open-pollinated families of this species. Thus, improving cold hardiness by within-family selection appears to hold much promise. Striking similarities in relative magnitudes of heritability estimates and genetic correlations in the full-sib family, compared with breeding populations, support the following hypotheses about the quantitative genetics of cold hardiness in this species: (i) heritability of cold hardiness (both broad-and-narrow-sense) is stronger in the spring than in the fall; (ii) cold hardiness of different shoot tissues in the same season is controlled by many of the same genes; and (iii) genetic control of fall cold hardiness is largely independent of cold hardiness in the spring.

Genetics of cold hardiness in a cloned full-sib family of coastal Douglas-fir

Variation in cold-hardiness traits, and their extent of genetic control and interrelationships, were investigated among individuals (clones) within a single large full-sib family of coastal Douglas-fir ( Pseudotsuga menziesii var. menziesii (Mirb.) Franco) from Oregon. Cold injury to needle, stem, and bud tissues was evaluated in fall 1996 and spring 1997 following artificial freeze testing of detached shoots collected from 4-year-old ramets (rooted cuttings). Variation among clones in cold-injury scores was significant (p < 0.01) for all shoot tissues in both fall and spring and averaged about three times the magnitude previously observed among open-pollinated families of this species. Thus, improving cold hardiness by within-family selection appears to hold much promise. Striking similarities in relative magnitudes of heritability estimates and genetic correlations in the full-sib family, compared with breeding populations, support the following hypotheses about the quantitative genetics of cold hardiness in this species: ( i) heritability of cold hardiness (both broad-and-narrow-sense) is stronger in the spring than in the fall; ( ii) cold hardiness of different shoot tissues in the same season is controlled by many of the same genes; and (iii) genetic control of fall cold hardi- ness is largely independent of cold hardiness in the spring.

Influence of second flushing on genetic assessment of cold hardiness in coastal Douglas-fir ( Pseudotsuga menziesii var. menziesii (Mirb.) Franco)

The consequences of second flushing for fall cold hardiness in coastal Douglas-fir ( Pseudotsuga menziesii var. menziesii (Mirb.) Franco) was investigated in 4-year-old trees from two genetic tests: 42 polycross families in British Columbia and 8 full-sib families in the state of Washington. Cold injury to needle and stem tissues was assessed in October and November in samples of both second-flushed and non-second-flushed shoots from the same trees following artificial freezing. Freeze damage to needles and stems in the second-flushed portion of shoots was 50–60% greater than in non-second-flushed shoots. Great care, therefore, should be taken to consistently sample the same shoot type when comparing cold hardiness of genotypes (or families) using artificial freeze testing. However, because the estimated genetic correlations in freeze injury between second-flushed and non-second-flushed shoots were moderately positive, scoring all trees for hardiness of one shoot type should provide fairly accurate rankings of genotypes for cold hardiness of both shoot types. We recommend scoring non-second-flushed shoots because the frequency of second flushing decreases relatively rapidly with increasing age in coastal Douglas-fir. Hardening of both second-flushed and non-second-flushed shoots was delayed in trees with higher proportions of second-flushed shoots in their crown. Thus, foresters should avoid planting families with high propensity to second flush on high fertility sites (i.e. sites that promote second flushing) susceptible to fall frost events.

Genetics of fall and winter cold hardiness of coastal Douglas-fir in Oregon

Genetic variation in fall cold hardiness was studied in two western Oregon breeding populations of coastal Douglas-fir (Pseudotsugamenziesii var. menziesii (Mirb.) Franco), one on the west slope of the Cascade Mountains and the other in the Coast Range. On six sampling dates (September, October, and November of 1992 and January, September, and October of 1993), shoot cuttings from 40 open-pollinated families in each of two progeny test sites for each breeding zone were subjected to artificial freezing at two test temperatures. Damage on each shoot was recorded as visible injury to needle, stem, and bud tissues separately. Considerable family variation was found for cold injury scores in all tissues in early fall to midfall, but differences were often smaller or nonsignificant in late fall and midwinter. Individual heritability estimates for needle cold injury were low (&lt;0.40) and generally decreased in late fall and midwinter. Family rankings for fall cold hardiness, however, are expected to be relatively consistent over sites and years, although needles appear to display more family-by-site interaction than stems or buds. Genetic correlations between tissues in cold injury varied considerably and were sometimes weak, indicating that the evaluation of a single tissue is probably not adequate for assessing overall cold hardiness of genotypes. Fall and winter cold hardiness seem to be largely under separate genetic control since genetic correlations between hardiness at these two stages were weak. This study confirms earlier results in Washington breeding populations and shows that coastal Douglas-fir families can be effectively ranked for fall cold hardiness by conducting artificial freeze tests on cut shoots in midfall (October) and scoring damage to stems and at least one other tissue.