Levels Of Cold Tolerance Research Articles

Relationship between guard cell length and cold hardiness in wheat

Identification of plant characters associated with cold tolerance is useful for the development of plant-breeding selection procedures and understanding the underlying mechanisms of cold hardiness. This research investigates the association of guard cell length with cold tolerance and examines the relationship between cell size, as estimated from guard cell length, and other characters previously found to be highly correlated with cold tolerance in wheat (Triticum aestivum L. em. Thell.). Guard cell length was compared with field survival, LT50, tissue water content, and plant erectness of cultivars representing a wide range of cold tolerance levels. The three most cold-tolerant cultivars had the smallest cells, while the cultivar with the largest cell size was a spring type. There were significant (P ≤ 0.05) correlations between guard cell length and all cold-tolerance-related characters considered. Differences in guard cell length were most closely related to field survival as measured by Field Survival Index (FSI). Stepwise regression analysis indicated that cell size explained 45% of the variability in FSI. Cell size combined with plant erectness and tissue water content explained 88% of the variability in FSI. LT50 and cell size together explained 96% of the variability in FSI. The effects of cell size on cold hardiness may relate to its influence on cell water content and cellular mechanical stress during intercellular ice-crystal formation and freezing-induced dehydration. Guard cell size should be a useful selection tool in cultivar development programs that have increased cold hardiness as the breeding objective. Key words:Triticum aestivum, winter wheat, cold hardiness, guard-cell length, cell size

Seasonal Change in Cold Tolerance of the House Spider, Achaearanea tepidariorum (Araneae: Theridiidae).

Field-collected nymphs of Achaearanea tepidariorum displayed significant seasonal variation in the level of cold tolerance. The whole body supercooling point (SCP), the absolute limit of freeze avoidance, was ranged from -8.1°C in August to -20.1°C in January, and the median lower lethal temperature (LLT 50), and indicator of chilling tolerance, from -2.1°C in August to -13.7°C in January. Seasonal depression of LLT 50 began to occur one month earlier than that of the SCP, suggesting that these two changes are induced by separate processes. The cold tolerance strategy in term of the seasonal patterns of SCP and LLT 50 was discussed.

Effect of rapid cold hardening on reproduction and survival of offspring in the housefly Musca domestica

Pupae (pharate adults) of the housefly Musca domestica show a rapid cold-hardening response in which transfer from 27 to −7°C for 2 h is lethal whereas prior acclimation at 0°C for only 3 h is sufficient to confer a high level of cold tolerance against subsequent exposure to −7°C for 2 h. When pupae were acclimated at 0°C for 3 h (=acclimated) or acclimated at 0°C for 3 h and then transferred to −7°C for 2 h (=cold shocked), the mean longevity of emerging females in both groups was 5 days less than in a control population. The mean daily oviposition of the cold-shocked females was also reduced by five eggs per day compared to the acclimated and control groups. The combined effects of a shorter life span and lower daily oviposition produced a significant reduction in mean total fecundity from 623 ± 73.6 (control) to 345 ± 54.9 (cold shocked) eggs per female. Additionally, the mean daily emergence of flies from eggs laid by the cold-shocked group was 14.2% lower than in the control. In all treatment groups egg viability decreased during the reproductive life of the female parent. These results suggest that rapid cold hardening and cold-shock exposure can reduce adult longevity. However, the acclimation response ensures survival in brief exposures to moderately low temperatures in a high proportion of the population that would otherwise die, providing an adequate base for population increase on return to more favourable conditions.

Genotypic Variation for Cold Tolerance in Winter and Facultative Barley

Improved winter survival of barley (Hordeum vulgare L.) may be achieved by developing genotypes that maintain an acceptable level of cold tolerance despite fluctuations in air and soil temperature. The cold tolerance of eight winter and facultative barley cultivars, a spring barley and a winter wheat (Triticum aestivum L.) was measured in controlled freeze tests of field‐grown material. The temperature lethal to 50% of each genotype population (LT50) was calculated from survival data. The LT50 values for each genotype were determined at multiple sampling dates at two locations over a 2‐yr period. Sampling dates were considered environments and these data were used to identify genotypes showing stable, or full‐season, cold tolerance. Genotypes were grouped according to patterns of comparable LT50 response across the six environments. The significant genotype group ✕ environment interaction detected in the analysis of groups and environments was due to changes in magnitude of response rather than changes of rank. Averaged across all environments. ‘Norstar’ winter wheat was significantly more cold tolerant than the barley germplasm, and there was little variation for cold tolerance among winter barley genotypes. Winter barley cultivars were more cold tolerant than facultative cultivars. Two joint regression stability parameters, the regression coefficient (b) and squared deviations from regression (S2d), revealed genotypic variation for full‐season cold tolerance.

Seasonal variation in generation time, diapause and cold hardiness in a central Ohio population of the flesh fly, Sarcophaga bullata

. 1 Generation time, diapause phenology and cold tolerance of the flesh fly, Sarcophaga bullata, were examined under confined natural conditions in central Ohio. In this locality, the fly can complete a maximum of four generations annually. 2 Very few pupae entered diapause in the first and second generations (May to July in 1988). In the third generation (August) 37% of the pupae entered an overwintering diapause, as did all pupae from the fourth generation (September). 3 The adult eclosion date in the spring and annual generation time can be predicted accurately from degree day data. 4 Cold tolerance of the field-overwintering portion of the population was high. After 30 days under field conditions, diapausing pupae readily survived a 7-day exposure to — 17°C. Glycerol appears to be the major cryoprotectant in S.bullata, and glycerol concentrations in the field population (95–142 mm) remained high throughout the winter. 5 In contrast, diapausing flies reared under laboratory conditions (20°C, 12:12 LD) were less cold tolerant, and glycerol concentrations were lower (6.9–21.2 mm). Field conditions thus promote the acquisition of high levels of cold tolerance, presumably as a consequence of the accumulation of higher concentrations of glycerol. 6 In spite of differences in the cold tolerance of laboratory and field flies, the supercooling points of the two groups of flies were nearly the same, thus implying that the supercooling point is not a good indicator of cold tolerance.

Insects at Low Temperature: A Predictable Relationship?

In the study of insect ecology it is convenient to classify the factors that determine the abundance of different species. Biotic and abiotic, (physical), density dependent and independent, and climate and competition, are examples of this descriptive terminology. While the value of such a classification is debatable, it is commonly accepted that weather is an important abiotic factor, which normally acts in a density-independent way. When considering the influence of climate on insects, a distinction should be made between effects occurring within and outside of the socalled favourable zone. Within the favourable zone, climate, particularly temperature, determines rate-based processes such as reproduction and development. Conditions outside the favourable zone prevent reproduction and development, and at the extremes, can become lethal (Dempster, 1975). For insects of the temperate region this switch from a favourable to an unfavourable climate is largely a seasonal phenomenon, peaking in summer and winter respectively. Similarly, the nature of the mortality factors acting on insects reflects this seasonal trend, with the effects of natural enemies and competition being most important from late spring to autumn, and low temperature the dominant influence in winter. The damage potential of most pest insects is a function of their abundance at the time when crops are most vulnerable to attack. It is therefore valuable to identify the factors that contribute to the annual cycle of mortality, especially those that might be used to predict patterns of future abundance. Forecasts of the likely migration dates, abundance and outbreak areas of pest species allow rational decisions to be made on the use of insecticides, particularly in years of low pest incidence. The need for predictive models of this type has been highlighted by the aphid and associated virus epidemics which have followed two successive winters with abnormally high temperatures, and the prospect of consistently higher winter temperatures as a result of global warming and climate change. Against this background, this paper outlines current ideas on the cold hardiness of temperate insects, demonstrates the importance of microclimates, and presents evidence to show that for some species, the level of winter survival is the primary determinant of their future abundance. The difficulties of predicting mortality from records of winter temperature and indices of cold hardiness are illustrated by reference to three species with differing levels of cold tolerance.

Sources for Tolerance to Cold in Cicer Species

Cold tolerance is an important prerequisite for successful winter sowing of chickpea (Cicer arietinum L.). In the Mediterranean region, winter sowing will increase productivity compared with the same crop sown traditionally in the spring. In the search for germplasm possessing a higher level of tolerance to cold than the cultivated species, 137 lines of eight wild annual Cicer species were evaluated during the 1987‐1988 and 1988‐1989 seasons at the International Center for Agricultural Research in the Dry Areas (ICARDA), Syria. Both seasons were effective for screening chickpea against cold, as the susceptible indicator was killed by cold spells each year. Most of the lines of C. bijugum K.H. Rech., C. echinosperum P.H. Davis, and C. reticulatum Ladiz. were tolerant to cold and had significantly higher levels of cold tolerance than the cultivated species. All lines of C. chorassanicum (Bunge) M. Popov, C. cuneatum Hochst. ex Rich., and C. yamashitae Kitamura, and all but one line of C. judaicum Boiss., were susceptible. Lines of C. pinnatifidum Jaub. & Spach showed both susceptible and tolerant reactions.

Microgeographic Adaptation to Temperature in Pitch Pine Progenies

-Localized variation in cold tolerance of pitch pine (Pinus rigida Mill.) seedlings from an area including a large frost pocket was examined over an autumn, winter and spring. Sizable differences in cold tolerance were discovered among population and individual-tree progeny samples, as measured by patterns of acclimation and maximum levels of cold tolerance achieved. Differences in cold tolerance were associated with local differences in temperature between populations separated by 8 km (over most of which the species occurs only sporadically), but not within a continuous population over a distance of 3.4 km.

Temperature-stress response in maize: a comparison of several cultivars

The protein synthetic response to a heat (28–41 °C) and a cold (28–4 °C) shock was studied in seedlings from 10 cultivars of maize with varying levels of cold tolerance. This response was compared by fluorography of one-dimensional polyacrylamide gels and immunoblot analysis. We utilized polyclonal antibodies against the 18 000 dalton (Da) heat-shock protein and the 73 000–89 000 Da heat-shock protein complex from Oh43 maize seedlings to ascertain antigenic similarity of these polypeptides. The heat-shock response varied in the numbers and relative molecular masses of the heat-shock proteins. Only three polypeptides appeared to be conserved across cultivars: a 93 000, 71 000, and 18 000 Da polypeptide. The cold-shock response varied from none to a dramatically altered pattern in a few cultivars. Thus, the heat- and cold-shock responses in these cultivars of corn differ in the types of polypeptides that are induced. All cultivars showed varying degrees of cross-reactivity when probed with the anti 18 000 Da heat-shock protein antibody. The inbred lines appeared to respond more to a cold shock than the hybrid lines but there was little relationship between the cold tolerance and the induction of a cold-shock response. Two of the cultivars demonstrated unique binding to a higher molecular weight polypeptide under control (28 °C) conditions. These data suggest that within species variation in both number and relative molecular weight of thermal stress polypeptides (heat and cold) is a function of genotype.Key words: heat shock, cold shock, cold tolerance, maize, gene expression.

INFLUENCE OF FALL APPLIED 2,4-D AMINE AND MCPA ON COLD HARDINESS AND OTHER AGRONOMIC CHARACTERS OF WINTER WHEAT AND RYE

The effects of 2,4-D and MCPA amine treatments on cold tolerance and other agronomic characters of winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) were studied in controlled environment and field trails. For both species, the level of cold tolerance achieved in controlled environments was reduced following exposure to 2,4-D and MCPA at rates up to 2.24 kg ha−1. In contrast, similar rates of fall applied 2,4-D and MCPA did not affect the cold tolerance of wheat and rye growing in the field. Treatment of plants from different seeding dates indicated that the observed field herbicide tolerance was not influenced by large differences in plant growth stage. Yield and other agronomic characters were also unaffected by fall 2,4-D and MCPA treatment. In contrast, broadleaf weed control was obtained with rates as low as 0.28 kg ha−1 for both herbicides, emphasizing the large safety margin between rates required for effective winter annual weed control and crop tolerance levels. From a practical standpoint, the influence of other management practices, such as delayed seeding, were of much greater importance in winter cereal production than the effects of commerical rates of 2,4-D or MCPA applied in the fall for broadleaf weed control.Key words: Wheat (winter), rye, 2,4-D amine, MCPA amine, cold tolerance

Cold‐Hardiness Response of Sequential Winter Wheat Tissue Segments to Differing Temperature Regimes1

This experiment was initiated to determine if low‐temperature acclimation in one part of a winter wheat plant (Triticum aestivum L.) can influence cold tolerance levels in other plant parts not exposed to cold‐acclimating temperatures. Whole plants and sequential plant segments were exposed to differing temperature regimes in a controlled environment chamber. The level of cold hardiness was determined in whole plant crowns by the regrowth method and in each tissue segment by the leachate conductivity method. Cold hardening of plant parts occurred in dependent of hardiness levels in other parts of the plant. The results indicated that plant response to temperature was the ultimate factor inducing cold hardiness. Reduced tissue moisture content enhanced the cold‐hardening ability of plant tissues, although it also was a plant response to cold acclimating temperatures. The moisture content of upper plant parts was controlled largely by root temperature rather than leaf or crown temperature, although low leaf temperature had some effect on water conductance through the leaves. Tissue segments with low moisture content were more cold hardy than comparable segments with higher moisture content under similar acclimation temperatures. However, tissue segments subjected to cold‐acclimating temperatures achieved greater levels of cold hardiness than comparable tissues of similar moisture content subjected to nonhardening conditions. Exposure temperature was most highly correlated with cold hardiness. Regression analysis indicated that acclimation temperature and tissue moisture content explained a large part of the variation in LT50 (temperature at which 50% of the plants were killed). There was little evidence of any translocatable substance in cold acclimated segments that was able to induce cold hardiness in nonacclimated segments of the plant.

SOURCES OF COLD TOLERANCE IN GRAIN SORGHUM

The term "cold tolerance" refers to the ability of sorghum (Sorghum bicolor (L.) Moench) genotypes to germinate, grow and produce satisfactory grain yields under conditions of relatively cold (but above-freezing) air and soil temperatures. Sources of cold tolerance and their usefulness in grain sorghum were investigated. Of 380 excessively tall, photoperiod-sensitive, and late-maturing accessions obtained from China, Ethiopia, and Uganda, 39 were cold-tolerant, 157 partially tolerant, and the remainder were susceptible when rated at physiological maturity. Highest levels of cold tolerance were found among accessions from Ethiopia (e.g. Alemaya 70, Jejewegere 935, and Muyra) and Uganda (Mabere, Magune, and Nyundo). Cold tolerance appeared to be a dominant trait. However, in cold-susceptible × cold-tolerant crosses there was a wide range of variation among cold-tolerant genotypes, and the frequency of highly tolerant segregates was less than 10% in the F2, suggesting that several genes controlled the inheritance of the character and that their effects were largely cumulative. A relatively large number of dwarf, photoperiod-insensitive, early-maturing, and cold-tolerant experimental lines were developed. Some of these were very well adapted to the highlands of Honduras, Kenya, and Mexico. In general, they were poorly adapted to high-latitude sites in the northwestern USA, southern Canada and West Germany.Key words: Cold-tolerant sorghum, adaptation, international testing, Sorghum bicolor

Planting Date and Cultivar Effect on Winter Rape Production1

AbstractThe optimum planting date of six cultivars of winter rape (Brassica napusL.) was determined at Moscow, Idaho on a Palouse silt loam (fine‐silty, mixed, mesic pachic, Ultic Haploxeroll). The cultivars were seeded in early August, mid‐August, late August, and mid‐September of 1978, 1979, and 1980. Data were taken on winter survival, seed yield, oil content, nodes to fist flower, reproductive nodes, and plant height. Optimum planting dates for winter rape were early to mid‐August. Both winter survival and seed yield declined when the cultivars were established in mid‐September. A significant cultivar ✕ planting date interaction for both seed yield and winter survival occurred only in the 1978–1979 trial in which plants were exposed to a minimum temperature of −30°C. Seed yield at the late planting date of this trial was closely associated to winter survival (r = 0.93**; df = 14). Oil content, nodes to first flower, reproductive nodes and plant height were not highly sensitive to planting date. The utilization of cultivars with high levels of cold tolerance could probably improve performance of late seeded rape fields. Average seed yields of 3376, 3866, and 4682 kg ha−1were observed in the 1978 to 1979,1979 to 1980, and 1980 to 1981 trials, respectively. Average oil content of individual cultivars ranged from 406 to 490 g kg−1. Based on the results of this study it appears that cultivars of winter rape recently introduced from northern Europe have excellent potential as oilseed crops in the Pacific Northwest.

Genetic variation for cold tolerance in selected and unselected maize populations

Abstract Inheritance of traits believed to indicate cold tolerance was studied in parent and selected populations of a Nebraska derivative of the Iowa Stiff Stalk Synthetic. A nested mating design was used in both populations, and progenies were evaluated in a growth chamber experiment. A differential temperature regime of 11.1°C for 14 h with light and 5.6°C for 10 h without light was used. The study indicated that both additive and dominance variance effects were involved in the traits studied. Non-additive genetic effects appeared to be operative in the parent population. Both additive genetic effects and dominance effects were operative in the selected population. In the selected population dominance effects were most apparent for seedling vigor. Changes in additive genetic effects might reflect accumulation of favorable cold tolerance alleles through selection. Maternal influences could not be ignored in interpretation of results. Selection to improve cold tolerance using growth chamber methods resulted in more desirable, but not significantly different levels of cold tolerance.

Hydrolytic Enzyme Differences in Cold‐Tolerant and Cold‐Sensitive Alfalfa1,2

AbstractThis investigation was part of a continuing effort to ascertain the role of soluble proteins in the development of cold tolerance of alfalfa, Medicago sativa L. The research was conducted to determine whether certain soluble proteins, known to be closely associated with the development of cold tolerance, exhibited hydrolytic enzyme activity. Cold‐tolerant ‘Vernal’ and cold‐sensitive ‘Sonora’ alfalfa plants grown for 66 days under simulated “summer” (nonhardening) and “winter” (hardening) conditions exhibited different levels of cold tolerance as indicated, by cold tolerance assays performed at three freezing temperatures. Sonora winter plants were only moderately tolerant to −6 C, whereas Vernal plants were well hardened to −8 C and were tolerant to −10 C. Soluble protein concentrations were higher in hardened than in unhardened plants, with differences in protein concentration greater for Sonora than Vernal. Localization of hydrolytic enzymes on polyacrylamide gels after disc electrophoresis and subsequent densitometric scanning of zymograms demonstrated that activities of amylases, leucine amino peptidases, and α‐esterases were greater in winter than summer samples of both cultivars; whereas ATPase activities were lower in winter than summer samples. Furthermore, differences between αaesterase levels of hardened and unhardened samples were greater than those of amylase or peptidase. New esterase forms and higher quantities of a heat‐stable amylase also were detected in hardened samples. Differences in enzyme solubility between distilled water and tris‐HCl extracts, related to environment, extractant, or cultivar influences, were evident for esterases and ATPase and for individual forms of amylase and peptidase. The large quantitative changes in amylases and esterases localized within gel column regions 7 and 8 of hardened Vernal zymograms implied a close relationship of these hydrolytic enzymes to the hardening process; whereas the decreased ATPase activities reflected an inverse relationship with cold tolerance. It is, therefore, reasonable to conclude that quantitative and qualitative differences in hydrolytic enzyme activity are evident between hardened and nonhardened plants. The differences among hydrolytic enzymes do not necessarily follow the same quantitative or qualitative pattern, and for this reason they should be studied collectively to understand the biochemistry of hardening.

Dehydrogenase Levels in Cold‐Tolerant and Cold‐Sensitive Alfalfa1,2

AbstractCertain soluble proteins are believed to be closely associated with cold tolerance. The objectives of this work were to determine whether the proteins exhibited dehydrogenase activity and if there were qualitative and/or quantitative differences in dehydrogenases between hardened and nonhardened plants. Cold‐tolerant ‘Vernal’ and cold‐sensitive ‘Sonora’ alfalfa (Medicago sativa L.) plants were grown for 66 days under simulated summer (non‐hardening) and winter (hardening) conditions, using growth chambers, and were assayed for the levels of cold tolerance developed at three freezing temperatures (−6, −8, and −10 C). To determine differences in dehydrogenases, soluble proteins were separated from extracts of crown and root tissues by polyacrylamide disc gel electrophoresis. Localization of dehydrogenases on gels and densitometric scanning of zymograms indicated that activities of glutamate, lactate, isocitrate, glucose‐6‐phosphate, 6‐phosphogluconate, nicotinamide adenine dinucleotide (NAD) malate and nicotinamide adenine dinucleotide phosphate (NADP) malate dehydrogenases were high in both cultivars exposed to hardening and were generally highest in Vernal. Percent increases for winter over summer levels of glutamate, lactate, glucose‐6‐phosphate, and 6‐phosphogluconate dehydrogenases were large compared with those of isocitrate, NAD‐malate, and NADP‐malate dehydrogenases. Moreover, the magnitude of change in enzyme activity between summer and winter plants also was influenced by extractant (distilled water, pH 7 or 0.10 M tris‐HCl, pH 7) and varied quantitatively according to the solubility of the dehydrogenases in the two extractants. Enzyme solubility differences related to cultivar or environmental influences and cold tolerance were also observed, especially for isocitrate dehydrogenase. Large quantitative differences in glucose‐6‐phosphate and lactate dehydrogenase activities and substantial increases in isocitrate and 6‐phosphogluconate dehydrogenases localized within gel column regions 7 and 8 of zymograms developed from winter samples implied a close relationship of these enzymes to cold tolerance. Forms of lactate, glucose‐6‐phosphate, and isocitrate dehydrogenases were present in hardened tissues that were not present in un‐hardened tissues. It is concluded that the observed differences in dehydrogenasees between hardened and non‐hardened plants are major indicators of the cold tolerant state. Based on these and past studies, the reactions analyzed by representative hydrolytic and dehydrogenase enzymes may serve as a working hypothesis for future studies concerning the mechanics of induction and the suspected catenary nature of the hardening process.

Electrophoretic studies of the relationship of peroxidases, polyphenol oxidase, and indoleacetic acid oxidase to cold tolerance of alfalfa

Two cultivars of alfalfa ( Medicago sativa L.), cold-tolerant Vernal and cold-sensitive Sonora, were grown under summer, winter, and dehardening environments to investigate the relationship of soluble proteins and enzyme activity and solubility characteristics to cold tolerance. Evaluations of cold-tolerance levels developed in crown and root samples were compared with results of soluble protein analyses and were in agreement with previously reported observations. Soluble protein content was associated with increases in cold tolerance and related to the environment from which samples were obtained; however, the degree of protein differences within samples of the same cultivar as well as between the two cultivars seemed to be influenced by the type of extractant used. Polyacrylamide disc gel electrophoresis of the extracted soluble proteins was performed on the basis of equal dry weights and equal quantities of protein. Amido black straining of gels indicated mainly quantitative changes and slight qualitative differences in component bands influenced by environment and extractant. Gels assayed for peroxidase, polyphenol oxidase, and indoleacetic acid oxidase enzymes exhibited mainly quantitative differences in constitutive isoenzyme components of both cultivars which were associated with environmental changes. Enzyme activities generally increased in winter, as cold tolerance and soluble protein content increased, and decreased during dehardening. The few qualitative differences in isoenzyme bands that were detected, appeared to be influenced by cultivar, environment, extractant, or substrate specificity differences. Variation in isoenzyme components between cultivars was maximum in summer samples, and minimum in winter samples, suggesting that overall reaction rates or activities of individual isoenzymes, preceding or during hardening, could be a limiting factor in cold-tolerance development.

Screening Sugarcane Populations for Cold Tolerance by Artificial Freezing1

Results of artificial freezing of young, potted sugarcane plants for 6 hours at —3 C were similar to field experience when plants were preconditioned in an unheated greenhouse. Precision control of freezer temperatures permitted the detection of levels of cold tolerance in the progeny of two cold tolerant parents. The method has been adapted to routine screening of seedlings for cold tolerance.