Bud Cold Hardiness Research Articles

COLD HARDINESS RESPONSE OF CABERNET SAUVIGNON AND CHARDONNAY GRAPEVINES TO WINTER PRUNING

At approximately two week intervals starting in mid-December, sets of four vines were pruned either 24, 48, or 72 hours prior to sampling for low temperature exotherm (LTE) analysis of buds. Prepruned samples were compared with unpruned samples. Buds for cold hardiness were taken from the fourth to the sixth node positions from each of the four vines. A total of 30 buds from each of the treatments were used for LTE analysis. In addition to these samples, analysis of bud cold hardiness was also made of these prepruned vines after approximately 3, 6, and 9 weeks and compared to unpruned vines.Despite the popular view that prepruning or pruning of grapevines during the winter reduces cold hardiness of the remaining buds, no differences were found between treatments during December, January, and February. Additional data on winter injury and budbreak will be presented.

Nitrogen Fertilization of White Riesling Grapes in Washington: Nitrogen Seasonal Effects on Bud Cold Hardiness and Carbohydrate Reserves

A commercial vineyard of White Riesling was used to study the influence of 0, 56, 112, and 224 kg N/ha on bud cold hardiness and carbohydrate reserves of bud and cane tissues over a three-year period. High N had significant effects on cold hardiness of buds, levels of soluble sugars and starches extracted from one-year-old bud or cane samples, only on a limited number of dates during the three years of the study. There was a positive relationship between bud hardiness and soluble sugars from bud or cane samples that was highly significant. Regression analysis of yearly data indicated there was no relationship between nitrogen level and either soluble sugars or starch in buds or canes. There was a positive relationship between air temperature and bud low temperature exotherms during the sampling period of each year, and an inverse relationship between air temperature and soluble sugar levels in both buds and canes. These data show the predominant role of air temperature on bud and presumably vine cold hardiness and the attendant changes in carbohydrate reserves. This study further demonstrates that under otherwise good management practices of pruning, cropload, irrigation, and rootstock selection, there should be little concern regarding a detrimental influence of nitrogen applied before harvest on cold hardiness or carbohydrate reserves of grapevines.

RESPONSE OF REPEATED 2,4-D SPRAYS ON THE NODE DIAMETER, INTERNODE LENGTH AND CARBOHYDRATES IN THE CANES AND COLD HARDINESS OF CONCORD GRAPE BUDS

Field grown high and low vigor Vitis labruscana cv, Concord grapevines were sprayed with 2,4-D amine in concentrations of 0, 2.5, 10 and 25 ppmw at 1st leaf; 1st and 3rd leaf; 1st, 3rd and 5th leaf and 1st, 3rd, 5th and 7th leaf stages of vine growth for two consecutive years. Cane and bud samples were collected for determining node diameter, internode length, carbohydrates in the canes, and T50 of buds. Data on yield and vegetable growth were also collected. There were significant differences among treatments in the node diameter and cold hardiness of buds (T50) both in high and low vigor vines. Repeated applications of 2,4-D reduced the cane diameter significantly but the carbohydrates in the canes were not affected. When 2,4-D symptoms were severe in July, yields were reduced by as much as 85%, but there was slight or no reduction in yield when symptoms were not severe.

Evaluation of Cold Hardiness of Blackberry Seedling Populations

Twelve seedling blackberry (Rubus spp.) populations were tested over 2 years for cold hardiness of stem and bud tissues. Seedling populations resulted from a partial diallele of crosses made among nine parents representative of three categories of cold hardiness. Viability testing of xylem, phloem, and bud tissues was conducted following exposure to a temperature lethal to 50% of tested tissue. Significant population effects (P < 0.05) occurred for xylem and bud cold hardiness in 1988 and for xylem, phloem, and bud cold hardiness in 1989. Results were similar for the 2 years, although there was a greater discrimination between populations for xylem and phloem cold hardiness in the 2nd year. Seedling populations having `Darrow' as a parent showed less tissue damage than the other eight populations. The populations having `Brison' as one parent showed consistently poor hardiness with the exception of one resulting from a cross of `Brison' × `Darrow'. This population showed consistently good hardiness, indicating that dominance effects may play a role in cold hardiness of blackberries.

Harvest Date as a Factor in Carbohydrate Storage and Cold Hardiness of Cabernet Sauvignon Grapevines

Cold-hardiness evaluations and soluble and insoluble-nonstructural carbohydrate analysis of dormant Vitis vinifera L. cv. Cabernet Sauvignon buds and cane tissue indicate a positive relationship between soluble carbohydrates and primary bud cold hardiness. Seasonal variations in soluble and insoluble carbohydrates appear to be related to changes in air temperatures and the dormancy status of the tissues. No differences were found in bud cold hardiness and only limited differences in carbohydrate levels of buds or stem tissues collected over 3 years from early harvest, normal harvest, or unharvested vines. These findings contrast with the widely held opinion that delayed harvest or failure to remove fruit results in reduced cold hardiness as a consequence of low storage carbohydrate content of the plants.

The effect of LAB 173711 and ethephon on time of flowering and cold hardiness of peach flower buds

Peach flowers are often killed during bloom by spring frosts. LAB 173711, a compound with abscisic (ABA)-like activity, and ethephon delayed flowering in peach trees. In greenhouse experiments, LAB 173711, at concentrations of 10−3–10−2 M, was most effective in delaying bloom when applied after a 5°C cold storage period, rather than before the dormancy breaking treatment. In contrast, ethephon delayed bloom most effectively when applied before 5°C cold storage; ethephon caused flower bud abscission when treatments were made after the chilling requirement had been satisfied. In field experiments, ethephon delayed flowering by 6–7 days, which reduced bud injury after a spring frost during bloom. No flower bud injury was found on ethephon-treated trees after temperatures of −4.3°C; whereas without ethephon 25% of the flower buds were frost damaged. LAB 173711 delayed the time to 50% bloom by 2–3 days. However, this was not long enough to avoid low-temperature injury to the flower buds.

Primary Bud Hardiness of Four Genotypes of Grapes in Arkansas

Four interspecific grape hybrids (Vitis spp.) developed in Arkansas were evaluated for primary bud hardiness by differential thermal analysis. Buds from two locations were analyzed over 2 years for acclimation, midwinter hardiness, and deacclimation. In addition, effects of two training systems on cold hardiness of buds were evaluated in one location. The buds of the two genotypes with the greatest component of V. vinifera in their ancestry acclimated more slowly than did the other genotypes. Ultimate midwinter bud hardiness was greater in the genotypes possessing less V. vinifera than other parentage. No effect on cold hardiness due to training system was noted. No natural winter freeze damage was observed on any of the genotypes in the period of observation.

Relationships among cold hardiness, root growth potential and bud dormancy in three conifers.

Greenhouse-cultured, container-grown ponderosa pine (Pinus ponderosa var. scopulorum Engelm.), interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) and Engelmann spruce (Picea engelmannii (Parry) Engelm.) were cold acclimated and deacclimated in growth chambers over 19 weeks. Stem cold hardiness, total new root length at 14 days and days to bud break were measured weekly. Relationships among cold hardiness, root growth potential (RGP) and bud dormancy suggest that cold hardiness, which can be measured quickly, could provide a useful basis for estimating the two other parameters. During cold acclimation, there was a lag period in which stem cold hardiness remained at -15 degrees C and RGP was at a minimum, in all three species. Douglas-fir and Engelmann spruce buds remained fully dormant during this lag period. Ponderosa pine buds had no chilling requirement for the loss of dormancy, and reached quiescence during the lag period. Immediately following the lag period, as stem cold hardiness progressed to -22 degrees C, RGP increased to a high plateau in all three species, and Douglas-fir and Engelmann spruce buds approached quiescence. Cold deacclimation and bud development began immediately on exposure to warm, long days, but RGP remained high until stem cold hardiness returned to approximately -15 degrees C. At bud break, cold hardiness and RGP were at the minimum.

Deep Supercooling in Stem and Bud Tissues of Pecan

Abstract Seasonal changes in deep supercooling and cold-hardiness of stem tissue and apical buds of pecan [Carya illinoensis (Wang enh.) C. Koch] cultivars were studied. All the pecan cultivars showed supercooling in stem and apical buds. Supercooling in stem and apical buds was maximal in early January and least in early spring. A good correlation between killing temperatures and freezing of supercooled water was found in apical buds. Similar results were observed for stem samples collected during early spring. Apical buds appeared to be more prone to injury during spring than stem tissue in all the pecan cultivars. In early April, stem samples of pecan cultivars were killed at or below –20.1C, whereas apical buds were killed at –16C or above. Apical buds of ‘Posey’ showed greater cold-hardiness than those of other pecan cultivars in midwinter and early spring.

Influence of Cultivars, Ground Covers, and Trickle Irrigation on Early Growth, Yield, and Cold Hardiness of Peaches on Fox Sand

Abstract Three cultivars (early, midseason, late), two ground covers (clean cultivation followed by temporary cover vs. permanent sod strips), and trickle vs. no irrigation were studied in a high-density (633 trees/ha) experimental peach orchard established in 1980 on Fox sand. Growth rate in the first 5 years was similar for all three cultivars. It was retarded up to 12% by permanent sod relative to temporary cover and enhanced up to 30% by trickle irrigation vs. no irrigation. Total marketable yields and that of large-sized fruit (>6.3 cm) were significantly influenced by cultivars in the first and second, but not the third year of production. Ground cover treatments did not influence total marketable yields, but did affect the yield of large fruit in one year. Irrigation increased total marketable yields each year and also increased the yield of large fruit. Yields were up to 30.7% higher in trickle vs. non-irrigated plots. Cold hardiness of flower buds and shoot xylem in 1982 was significantly influenced by cultivar and irrigation treatments, but not by ground cover treatments; In 1984, each of these factors affected cold hardiness. Foliation in 1984 was affected by ground cover and irrigation treatments but not by cultivars. The best treatment combination across cultivars for management of the orchard floor consisted of permanent sod strips of creeping red fescue (Festuca rubra L.) in the row middles combined with trickle irrigation in the tree row.

Nitrogen Fertilization and Rootstock Effects on Wood Maturation and Dormant Bud Cold Hardiness of cv. Chardonnay Grapevines

Two rootstocks and three nitrogen fertilization rates were evaluated for their effects on wood maturation, bud survival, and bud cold hardiness of cv. Chardonnay grapevines. Nitrogen fertilizer, applied at up to 84 kg/ha/ year, had little or no effect on those responses. Vines grafted to cv. Elvira rootstock demonstrated more complete wood maturation than vines grafted to cv. Couderc-3309 rootstock. The degree of wood maturation was apparently an indirect consequence of rootstock effects on vine size and canopy density. Bud mortality due to low temperature exposure in the field was slightly greater for vines grafted to Couderc-3309 than for vines grafted to Elvira. Artificial freezing assays did not reveal consistent rootstock effects on scion bud cold hardiness when buds were collected from visually mature nodes.

Factors Affecting Exotherm Detection in the Differential Thermal Analysis of Grapevine Dormant Buds

Abstract Differential thermal analysis was evaluated as a means of determining the cold hardiness of excised dormant buds of Vitis vinifera L. cv. Chardonnay grapevines. The manner in which buds were excised and cooled affected the freezing characteristics of bud primordia. Buds excised with 1 to 2 mm of subjacent nodal tissue exhibited both high temperature exotherms (HTEs) and low temperature exotherms (LTEs). HTEs apparently resulted from freezing of supercooled moisture in bud scales and/or in the subjacent nodal tissue and occurred at inconsistent temperatures. Cooling similarly excised buds on a water-saturated substrate caused HTEs to occur at −4° to −8°C and did not affect the occurrence of LTEs, which were consistently associated with primordia death. Median LTEs associated with primary bud death were 1.5° to 2.0° warmer than LT50s derived from temperature/survival freezing tests of similar buds. Buds killed by freezing did not supercool appreciably when refrozen. Bud cold hardiness increased when single-node cuttings were exposed to a step-wise cooling cycle; however, the ability to detect exotherms decreased under these conditions. The decreased detection of exotherms was due to increased bud death and, presumably, a decrease of freezable (and thus detectable) moisture in the supercooled primordia of viable buds. DTA provides a useful and reliable means of determining grapevine bud cold hardiness when conducted in a standardized fashion.

Defoliation, Flower Bud Cold Hardiness, and Bloom Date of Peach as Influenced by Pruning Treatments

Abstract Mature ‘Sunqueen’ peach [Prunus persica (L.) Batsch] trees were dormant pruned, summer pruned, or summer topped for 4 consecutive years. Dormant-pruned trees defoliated slightly earlier than summer-pruned trees, but the onset and duration of terminal vegetative bud rest was not influenced by pruning treatment. Compared to dormant pruning, summer topping slightly reduced cold hardiness of flower buds on 2 of 4 test dates in 1982, but not in 1984. Bloom on vertical shoots in the upper canopy was advanced by summer pruning and by summer topping in both 1982 and 1983. Bloom development at other canopy positions was not influenced by pruning treatment.

Effect of Paclobutrazol on the Vegetative Growth, Yield, Quality, and Winterhardiness of Buds of ‘Concord’ Grape

Abstract Paclobutrazol, trunk-applied at 3 stages of vine growth, reduced the shoot length of Vitis labruscana Bailey ‘Concord’ vines. Budbreak was delayed by 3-5 days in treated vines compared to controls. There was no effect of treatments on pruning weight, fruit quality, and midwinter cold hardiness of buds. Chemical names used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).

Responses of Young Chardonnay Grapevines to Shoot Tipping, Ethephon, and Basal Leaf Removal

Shoot tipping, apical ethephon application, basal leaf removal, and lateral shoot removal were evaluated for two years as means of reducing shade in the fruiting/renewal region of young Chardonnay grapevines pruned to a low head and trained to bilateral canes. Tipping shoots or apical ethephon application effectively controlled shoot elongation and caused minimal terminal or lateral shoot regrowth. These treatments did not measurably alter the light environment of the fruiting/renewal region relative to vines receiving no canopy manipulation. Intracanopy insolation was, however, significantly increased by removal of lateral shoots. Canopy treatments did not significantly affect yields, pruning weights, or bud cold hardiness in either year; however, opening the fruiting region of the canopy by lateral shoot and/or basal leaf removal generally reduced titratable acidity and malic acid and significantly reduced the incidence of botrytis bunch rot.

Deep Supercooling in Most Tissues of Wintering Sasa senanensis and Its Mechanism in Leaf Blade Tissues

Cold hardiness of leaf blades, leaf sheaths, culms, rhizomes, and leaf buds in wintering Sasa senanensis (Fr. et Sav.) Rehder, a dwarf bamboo, was studied paying special attention to the types of resistance mechanisms which were determined with differential thermal analysis. Coincidence of LT(25) (lethal temperature at which 25% of the tissues are injured) with the initiation temperature of LTE (low temperature exotherm) suggested that all of these tissues described above owe their cold hardiness mechanism mostly to deep supercooling. Deep supercooling in leaf blades was also substantiated with microscopic observations, suggesting that the units of supercooling were minute tissues compartmentalized by longitudinal and cross veins. It was also shown that cooling rates and storage of shoots at -5 degrees C for 1 to 5 days in the ice-inoculated state did not greatly affect the supercooling ability of leaf blades. Sasa senanensis seemed to exhibit a unique strategy against prolonged subzero temperature, and its leaves would be a good system for the study on mechanisms of deep undercooling in plants.

Cold Hardiness and Temperature Responses of Healthy and Mildew-Infected Terminal Buds of Apple During Dormancy

Cold Hardiness and Temperature Responses of Healthy and Mildew-Infected Terminal Buds of Apple During Dormancy

Effects of Cane Length and Dormant Season Pruning Date on Cold Hardiness and Water Content of Concord Bud and Cane Tissues

Pruning studies were conducted in Concord vineyards over a five year period to determine the effects of dormant season pruning date and cane length on cold hardiness and water content of buds and canes as assessed by field mortality and artificial freezing test. In spring, fall-pruned vines showed more field bud kill than unpruned controls, but results of artificial freezing tests were inconsistent. Although gross water content of primary buds was inversely related to cold hardiness in a general way, specific hardiness differences could not be correlated with changes in water content.

An Exotherm Sensor for Measuring the Cold Hardiness of Deep-supercooled Flower Buds by Differential Thermal Analysis1

Abstract The low temperature exotherms of deep-supercooled flower buds have been found to be associated with freezing injury of the primordia. Differential thermal analysis of small buds with copper-constantan thermocouples often results in insufficient sensitivity, making it difficult to distinguish exotherms from background interference. The signal produced by the exotherm was significantly increased by utilizing a heat flux plate made from a thermoelectric module and thermal conducting paste. Differences in exotherms between nodes with one bud and with 2 buds could be detected with the thermoelectric module. More exotherms were detected from a given number of flower buds with the thermoelectric module than with thermocouples.

Comparison of Flower Bud Cold Hardiness of Several Cultivars of Rhododendron spp.12

Abstract Five evergreen rhododendron cultivars were compared for flower bud cold hardiness in laboratory freezing studies on 6 dates. ‘Roseum Elegans’, ‘Catawbiense Boursalt’ and ‘Boule de Neige’ were more cold hardy on most sampling dates than ‘America’ and ‘Lee’s Dark Purple’. The relative cold hardiness of these 5 cultivars was consistent on several winter dates over several years. Injured florets were black and readily separated from uninjured white florets upon dissection of the inflorescence bud after freezing.