COLD HARDENING AND COLD HARDINESS OF YOUNG WINTER RYE SEEDLINGS AS AFFECTED BY STAGE OF DEVELOPMENT AND TEMPERATURE

1960 ◽  
Vol 38 (3) ◽  
pp. 353-363 ◽  
Author(s):  
J. E. Andrews
Keyword(s):  
Winter Wheat ◽  
Cold Hardiness ◽  
Rapid Decrease ◽  
Genetic Differences ◽  
Cold Hardening ◽  
Winter Rye ◽  
Stages Of Development ◽  
Stage Of Development ◽  
High Level ◽  
Two Stages

Young winter rye seedlings, grown and hardened at 1° or 1.5 °C in the dark, developed a high level of cold hardiness at two stages prior to emergence of the first leaf. The first maximum occurred when coleoptiles were less than about 1 mm in length and was followed by a decrease in hardiness. A second and higher maximum occurred when coleoptiles were about 15–30 mm in length (5 weeks at 1.5 °C; 7 weeks at 1 °C) and it was followed by a rapid decrease in hardiness beginning at about the time the leaf broke through the coleoptile. Genetic differences corresponding with those obtained in the field were established by hardening seedlings for 7 weeks at 1 °C and exposure to −15 °C for 16 hours or by hardening for 5 weeks at 1.5 °C and exposure to −14 °C for 16 hours. The use of a lower (−4 °C) hardening temperature resulted in a large increase in cold hardiness at the younger stages of development but little or no increase where seedlings had already reached a maximum of hardiness from exposure to 1.5 °C for 5 weeks. Satisfactory genetic differences were not determined by exposure to −14 °C for 16 hours after hardening at −4 °C. In general the response to hardening of young winter rye seedlings was similar to that found with winter wheat.

COLD HARDINESS OF SPROUTING WHEAT AS AFFECTED BY DURATION OF HARDENING AND HARDENING TEMPERATURE

1960 ◽  
Vol 40 (1) ◽  
pp. 94-103 ◽  
Author(s):  
J. E. Andrews
Keyword(s):  
Winter Wheat ◽  
Cold Hardiness ◽  
Freezing Temperature ◽  
Rapid Decrease ◽  
Stage Of Development ◽  
Wheat Seeds

The cold hardiness of sprouting winter wheat seeds, as measured by exposure to −15 °C. for 16 hours, increased rapidly during the first 5 weeks of hardening and decreased rapidly between the seventh and eleventh week of hardening at 1.5 °C. in the dark. With a slightly higher hardening temperature (3.5 °C.) in the dark, a lower level of cold hardiness resulted; cold hardiness reached a maximum with 4 weeks of hardening and then decreased. Material grown at 5 °C. did not develop sufficient cold hardiness to withstand the freezing temperature. The application of supplementary light during hardening at 3.5 °C. resulted in a slight increase in average hardiness but did not prevent the rapid decrease in hardiness after the fourth week of growth.Sprouting winter wheat will harden to cold in the dark. The ultimate level of cold hardiness attained depends on the hardening temperature, the duration of hardening, and the stage of development of the seedling. Small changes in these factors can result in large differences in cold hardiness.

Duration of hardening and cold hardiness in winter wheat

1979 ◽  
Vol 57 (14) ◽  
pp. 1511-1517 ◽  
Author(s):  
D. W. A. Roberts
Keyword(s):  
Winter Wheat ◽  
Cold Hardiness ◽  
Cold Resistance ◽  
Maximum Level ◽  
Late Winter ◽  
Carbohydrate Reserves ◽  
Stage Of Development ◽  
Temperature Regimes ◽  
Number Of Leaves ◽  
Additional Reason

Experiments in which winter wheat plants were exposed to two different controlled hardening-temperature regimes (constant 3 °C, and 5.5 °C (day): 3.5 °C (night)) for long periods (up to 15 weeks) indicate that cold hardiness changes with time.The cold hardiness in plants grown from seed at 3 °C drops rapidly immediately after moistening and reaches a minimum 2–3 weeks later. Hardiness then begins to increase and reaches a maximum that lasts approximately from the 7th to the 11th week of growth after which it slowly declines.The patterns of change in cold hardiness during growth at 3 °C, and 5.5 °C:3.5 °C were almost synchronous if hardiness was plotted against duration of hardening, but were not synchronous if hardiness was plotted against stage of development as measured by the number of leaves produced. A somewhat similar result was obtained if plants grown for 3 weeks at 21 °C before hardening were compared with plants grown from dry seeds under the same hardening conditions. These experiments show that duration of hardening is more important in determining the level of cold resistance and the ability of wheat to retain its cold resistance than is stage of development, as measured by the number of leaves produced at the time cold resistance is measured.When plants seeded outdoors in mid-September were transferred at various dates (0–30 weeks after seeding) during the fall or winter to standardized hardening conditions in a growth cabinet for 0–15 weeks before freezing, their cold resistance changed in a way that suggests that plants in the field undergo the same pattern of changes in cold resistance as plants reared continuously in a growth chamber. This result suggests that the long exposure to hardening temperatures is one of the reasons why wheat in the field has less cold resistance in late winter than in autumn. Loss of carbohydrate reserves during winter may be an additional reason for this phenomenon.Under both growth cabinet and field conditions, increasing cold hardiness coincided with vernalization. Maximum cold hardiness was retained for several weeks after the completion of vernalization. These results suggest that the development of the maximum level of cold resistance may be related to the vernalization process.

DEHARDENING OF WINTER WHEAT AND RYE UNDER SPRING FIELD CONDITIONS

1977 ◽  
Vol 57 (4) ◽  
pp. 1049-1054 ◽  
Author(s):  
D. B. FOWLER ◽  
L. V. GUSTA
Keyword(s):  
Moisture Content ◽  
Winter Wheat ◽  
Cold Hardiness ◽  
Dry Weight ◽  
Test Site ◽  
Triticum Aestivum L ◽  
Winter Rye ◽  
Fresh Weight ◽  
Seeding Date ◽  
Secale Cereale L

Changes in cold hardiness (LT50), fresh weight, dry weight and moisture content were measured on crowns of winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) taken from the field at weekly intervals in the spring of 1973 and 1974 at Saskatoon, Sask. In all trials, Frontier rye came out of the winter with superior cold hardiness and maintained a higher level of hardiness during most of the dehardening period. For cultivars of both species, rapid dehardening did not occur until the ground temperature at crown depth remained above 5 C for several days. Changes in crown moisture content tended to increase during dehardening. Over this same period crown dry weight increased for winter rye but did not show a consistent pattern of change for winter wheat. Two test sites were utilized in 1974. One site was protected by trees and the other was exposed. General patterns of dehardening were similar for these two sites, but cultivar winter field survival potentials were reflected only by LT50 ratings for the exposed test site. The influence of fall seeding date on spring dehardening was also investigated. Late-seeded wheat plots did not survive the winter in all trials. However, where there was winter survival, no differences in rate of dehardening due to seeding date were observed.

An apparent relationship of soluble sugars with hardiness in winter wheat varieties

1975 ◽  
Vol 53 (19) ◽  
pp. 2198-2201 ◽  
Author(s):  
D. G. Green ◽  
C. D. Ratzlaff
Keyword(s):  
Winter Wheat ◽  
Cold Hardiness ◽  
Soluble Sugars ◽  
Cold Hardening ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
Wheat Cultivars ◽  
Wheat Varieties ◽  
Hardening Process ◽  
Winter Wheat Cultivars

Soluble carbohydrate patterns of two hardy winter wheat cultivars and two less hardy cultivars were compared during the cold-hardening process. Soluble carbohydrates increased in concentration as the seedlings developed and the cold-hardening process occurred. The largest soluble carbohydrate differentials between the hardy and less hardy winter wheat cultivars occurred in the sucrose and raffinose fractions. The accumulation of sucrose and raffinose in wheat growing at 7.2 °C–0.5 °C day–night was greater in the two less hardy winter wheat cultivars. An inverse relationship existed between soluble sugars and cold hardiness in the four cultivars studied.

POTENTIAL FOR WINTER WHEAT PRODUCTION IN SASKATCHEWAN

1976 ◽  
Vol 56 (1) ◽  
pp. 45-50 ◽  
Author(s):  
D. B. FOWLER ◽  
L. V. GUSTA ◽  
K. E. BOWREN ◽  
W. L. CROWLE ◽  
E. D. MALLOUGH ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Cold Hardiness ◽  
Winter Survival ◽  
Winter Rye ◽  
Wheat Cultivars ◽  
Winter Cereal ◽  
Brown Soil ◽  
Soil Zone ◽  
Winter Wheat Cultivars ◽  
Gray Soil

Winter cereal trials consisting of 10 cultivars representing cold hardiness potentials ranging up to the hardiness of Frontier winter rye were seeded at test sites throughout Saskatchewan for 2 yr. At most sites in the Brown soil zone only winter rye survived without extensive winter damage. At sites in the Black and Gray soil zones, winter survival was sufficient to provide agronomic data for several winter wheat cultivars. Considerable yield compensation took place in stands exhibiting partial winterkill, and as a result hardier cultivars did not always demonstrate a yield advantage.

scholarly journals A comparative study in aggression between adolescent boys and girls of tribal and non-tribal students in Chitagong Hill Tracts

1970 ◽  
Vol 2 (2) ◽  
pp. 79-84
Author(s):  
Rasel Ahmed ◽  
M Enanul Haque
Keyword(s):  
Empirical Investigation ◽  
Late Adolescents ◽  
Late Adolescent ◽  
Adolescent Boys ◽  
Chittagong Hill Tracts ◽  
Stages Of Development ◽  
Race And Gender ◽  
Stage Of Development ◽  
And Gender ◽  
Two Stages

The present study was an effort to conduct an empirical investigation behaviour on aggression in adolescent boys and girls of tribal (i.e. Chakma) and non-tribal (i.e. Bengali) students in Chittagong Hill Tracts. A sample consisting of 360 respondents was selected from tribal (N = 160) and non-tribal (N = 160) subjects. Each group was equally divided into boys and girls. Each gender was then equally divided into early and late adolescents. Thus, the study used a 2×2×2 factorial design representing two races (Chakma/Bengali), two genders (boys/girls) and two stages of development (early adolescence/late adolescence). The Measure of Aggressive Behaviour (MAB) was administered on the sample for data collection. Regardless of gender and stage of development, tribal respondents were found to express significantly higher rates of aggression than non-tribal respondents. Again, regardless of race and stage of development, boys expressed significantly higher rates of aggression than girls. Similarly, regardless of race and gender, respondents at early adolescent stage expressed significantly higher rates of aggression than the respondents at late adolescent stage. Key words: Aggression; adolescence; race; sex; stages of development DOI: 10.3329/jles.v2i2.7502 J. Life Earth Sci., Vol. 2(2) 79-84, 2007

The effect of CCC and gibberellins A3 and A7 on the cold hardiness of Kharkov 22 MC winter wheat

1971 ◽  
Vol 49 (5) ◽  
pp. 705-711 ◽  
Author(s):  
D. W. A. Roberts
Keyword(s):  
Winter Wheat ◽  
Cold Hardiness ◽  
Morphological Changes ◽  
Cold Hardening ◽  
Chlorocholine Chloride

Continuously feeding a suitable concentration (3 × 10−5 or 3 × 10−4 M) of chlorocholine chloride (CCC) through the roots of Kharkov 22 MC winter wheat grown at both hardening (4 to 6 °C) and non-hardening (21°) temperatures induced small increases in its cold hardiness. In plants grown at 21 °C supplying 3 × 10−3 M CCC reduced cold hardiness. Under hardening conditions gibberellins A3 and A7 and under non-hardening conditions gibberellin A3 reduced the cold hardiness of Kharkov 22 MC. CCC produced morphological changes in plants grown at 21 °C that partially duplicated those induced by growing the plants at 6 °C. In plants grown at 6 °C gibberellins A3 and A7 produced morphological changes that caused the plants to partially resemble those grown at 21 °C. These results are discussed in relation to the hypothesis that one of the changes accompanying cold hardening in winter wheat is a reduction of the content of endogenous gibberellins. The conclusion is reached that if a reduction in gibberellin levels occurs it can only account for a part of the change in cold hardiness produced by natural hardening temperatures.

EFFECT OF RUSSIAN WHEAT APHID ON COLD HARDINESS AND WINTERKILL OF OVERWINTERING WINTER WHEAT

1990 ◽  
Vol 70 (4) ◽  
pp. 1033-1041 ◽  
Author(s):  
J. B. THOMAS ◽  
R. A. BUTTS
Keyword(s):  
Triticum Aestivum ◽  
Winter Wheat ◽  
Cold Hardiness ◽  
Triticum Aestivum L ◽  
Russian Wheat Aphid ◽  
Cold Hardening ◽  
Winter Survival ◽  
Crop Damage ◽  
Risk Of Fall ◽  
Cold Hardy

Russian wheat aphid (RWA) (Diruaphis noxia (Mordvilko)) is a new and cold-hardy pest of temperate cereals in western Canada. In view of the risk of fall infestation of winter wheat (Triticum aestivum L. em. Thell.), this study was made to establish whether feeding by RWA can interfere with cold hardening and plant survival of overwintering winter wheat. Feeding by RWA significantly increased the LT50 of field-hardened Norstar winter wheat by + 2 to + 4 °C. Application of 400 g (a.i.) ha−1 of the insecticide chlorpyrifos in mid-October to control severe RWA infestations in two different fields of Norstar winter wheat significantly improved winter survival of the crop. The pattern of winterkill within the two fields suggested that this protective effect of chlorpyrifos was greatest in areas where microtopography resulted in the least accumulations of snow and cold stress was most intense. It was concluded that heavy RWA infestation in the fall significantly reduced freezing tolerance of winter wheat and increased the likelihood of winterkilling of the crop by severe cold.Key words: Winter survival, cold hardening, Diuraphis noxia, insecticide, chlorpyrifos, Triticum aestivum, crop damage

ASSOCIATION BETWEEN ASCORBIC ACID CONCENTRATION AND COLD HARDENING IN YOUNG WINTER WHEAT SEEDLINGS

1961 ◽  
Vol 39 (3) ◽  
pp. 503-512 ◽  
Author(s):  
J. E. Andrews ◽  
D. W. A. Roberts
Keyword(s):  
Ascorbic Acid ◽  
Winter Wheat ◽  
Acid Content ◽  
Cold Hardiness ◽  
Ascorbic Acid Content ◽  
Wheat Varieties ◽  
Wheat Seedlings ◽  
Stage Of Development ◽  
Cold Hardy ◽  
Winter Wheat Varieties

The ascorbic acid content of winter wheat varieties, germinated in the dark at various temperatures on the surface of moist vermiculite, was much higher at a hardening temperature of 1.5 °C than at higher temperatures of 5°, 10°, or 20 °C. There were no differences between the ascorbic acid contents of wheat grown at the three higher temperatures. Ascorbic acid content was dependent on the stage of development at all temperatures. At 1.5 °C, the ascorbic acid content increased during the first 6 weeks of growth (shoots about 15 mm) and then decreased rapidly. This variation in ascorbic acid content was closely associated with the increase and decrease in cold hardiness of wheat grown under similar conditions.Ascorbic acid content was highest in shoots, intermediate in roots, and lowest in the endosperm of wheat grown for 6 weeks at 1.5 °C.At hardening temperatures (1.5° and 3 °C) the more cold hardy winter wheat varieties had higher contents of ascorbic acid. At higher temperatures the differences between varieties were small. The ranking of varieties by ascorbic acid content could be influenced by relative stages of growth.Artificial cold hardiness was imparted to winter wheat seedlings by feeding them aqueous ascorbic acid solutions of adequate concentration. The ascorbic acid content of leaves required for artificial hardening appeared to be similar to that accumulated in sprouts hardened fully by growth at low temperature.

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

1986 ◽  
Vol 66 (4) ◽  
pp. 837-843
Author(s):  
D. B. FOWLER ◽  
M. L. GRAHAM ◽  
R. ASHFORD
Keyword(s):  
Winter Wheat ◽  
Cold Tolerance ◽  
Weed Control ◽  
Cold Hardiness ◽  
Management Practices ◽  
Safety Margin ◽  
Herbicide Tolerance ◽  
Winter Rye ◽  
Agronomic Characters ◽  
Winter Cereal

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

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