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.

COLD HARDENING AND DEHARDENING RESPONSES IN WINTER WHEAT AND WINTER BARLEY

1975 ◽  
Vol 55 (2) ◽  
pp. 529-535 ◽  
Author(s):  
M. K. POMEROY ◽  
C. J. ANDREWS ◽  
G. FEDAK
Keyword(s):  
Winter Wheat ◽  
Cold Hardiness ◽  
Maximum Level ◽  
Freezing Temperature ◽  
Triticum Aestivum L ◽  
Winter Barley ◽  
Lethal Temperature ◽  
Hordeum Vulgare L ◽  
Wheat Seedlings ◽  
Time Required

Increasing the duration of freezing of Kharkov winter wheat (Triticum aestivum L.) demonstrated that severe injury does not occur to plants at a freezing temperature (−6 C) well above the lethal temperature for at least 5 days, but progressively more damage occurs as the temperature approaches the killing point (−20 C). High levels of cold hardiness can be induced rapidly in Kharkov winter wheat if seedlings are grown for 4–6 days at 15 C day/10 C night, prior to being exposed to hardening conditions including diurnal freezing to −2 C. The cold hardiness of Kharkov and Rideau winter wheat seedlings grown from 1-yr-old seed was greater than that from 5-yr-old seed. Cold-acclimated Kharkov winter wheat and Dover winter barley (Hordeum vulgare L.) demonstrated the capacity to reharden after varying periods under dehardening conditions. The time required to reharden and the maximum level of hardiness attained by the plants was dependent on the amount of dehardening. Considerable rehardening was observed even when both dehardening and rehardening were carried out in the dark.

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.

CHANGES IN COLD HARDINESS ACCOMPANYING DEVELOPMENT IN WINTER WHEAT

1968 ◽  
Vol 48 (4) ◽  
pp. 369-376 ◽  
Author(s):  
D. W. A. Roberts ◽  
M. N. Grant
Keyword(s):  
Low Temperature ◽  
Winter Wheat ◽  
Cold Hardiness ◽  
Cold Resistance ◽  
Winter Survival ◽  
Growth Chamber ◽  
Temperature Resistance ◽  
Varietal Differences ◽  
Low Temperature Resistance ◽  
Exact Timing

The cold resistance of 18 varieties of winter wheat hardened in a growth chamber was studied at various stages of development and the results were compared with the field survival of these varieties.In the growth chamber two maxima of cold resistance were found, the first for the dry or freshly moistened seed and the second when plants had approximately 4 to 6 leaves. Varietal differences were found in the exact timing of this second maximum and in its duration. As a result, some varieties changed their rank for cold resistance as they developed.Partial agreement was observed between the field survival of varieties sown at different dates and the changes in cold resistance of these varieties as they developed in the growth chamber.From these tests, a procedure has been developed that should enable fairly reliable predictions to be made of field survival of winter wheat in any area where low-temperature resistance is the major factor in winter survival.

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.

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.

Effects of Molybdenum and Phosphorus Fertilizers on Cold Resistance in Winter Wheat

2015 ◽  
Vol 38 (5) ◽  
pp. 808-820 ◽  
Author(s):  
Zhaojun Nie ◽  
Shuying Li ◽  
Chengxiao Hu ◽  
Xuecheng Sun ◽  
Qiling Tan ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Cold Resistance ◽  
Phosphorus Fertilizers

Cytokinins and abscisic acid in hardening winter wheat

1990 ◽  
Vol 68 (7) ◽  
pp. 1597-1601 ◽  
Author(s):  
John S. Taylor ◽  
Munjeet K. Bhalla ◽  
J. Mason Robertson ◽  
Lu J. Piening
Keyword(s):  
Triticum Aestivum ◽  
Abscisic Acid ◽  
Winter Wheat ◽  
Leaf Tissue ◽  
Triticum Aestivum L ◽  
Early Spring ◽  
Growth Chamber ◽  
Late Winter ◽  
Sequence Of Events ◽  
Freeze Dried

During overwintering in a northern climate, winter wheat goes through a hardening process, followed by dehardening in late winter – early spring. This sequence of events may be partially controlled by changes in endogenous hormone levels. Crowns and leaf tissue from field grown winter wheat (Triticum aestivum L. cv. Norstar) seeded at the beginning of September were collected and freeze-dried at monthly intervals during the winters of 1985–1986 and 1986–1987. Material was also sampled and freeze-dried from seedlings grown in a growth chamber under hardening conditions (21 °C for 2 weeks plus 3 °C for 6 weeks) or nonhardening conditions (3 weeks at 21 °C). The tissues were analysed for cytokinins and abscisic acid. Cytokinin levels, measured with the soybean hypocotyl section assay, declined from October onwards and then rose to a peak in late winter (January and February, winter 1986–1987; February and March, winter 1985–1986), subsequently declining again. Abscisic acid, quantitated as the methyl ester by gas chromatography with an electron capture detector, increased in level from October to December, then decreased to a relatively low level between January and March. Hardened seedlings from the growth chamber contained significantly higher abscisic acid levels and significantly lower cytokinin levels than did the nonhardened seedlings. Key words: abscisic acid, cytokinins, hardening, Triticum aestivum, winter wheat.

Early spring and late autumn response to applied nitrogen in four grasses

1980 ◽  
Vol 94 (2) ◽  
pp. 443-453 ◽  
Author(s):  
D. Wilman ◽  
A. A. Mohamed
Keyword(s):  
Perennial Ryegrass ◽  
Leaf Blade ◽  
Unit Area ◽  
Total Yield ◽  
Early Spring ◽  
Late Winter ◽  
Number Of Leaves ◽  
Four Levels ◽  
Leaf Extension ◽  
Applied Nitrogen

SummaryThe regrowth of Aberystwyth S. 23 perennial ryegrass, S. 24 perennial ryegrass, S. 59 red fescue and S. 170 tall fescue was studied in field swards, comparing four levels of applied nitrogen, for 8 weeks following a clearing cut. The clearing cuts were in mid-October, mid-February and mid-March in each of 3 years, different plots being used on each occasion.The application of N increased the number of leaf primordia, the number of un-emerged leaves, the rate of leaf emergence and death, leaf blade length, width and weight, sheath length, number of leaves per unit area of ground and proportion of green tissue in total yield. The application of N had little effect on the number of leaves per tiller and tended to reduce weight per unit area of leaf blade. The increase in size, weight and number of leaf blades appeared to be major reasons for the positive effect of applied N on yield, previously reported; and the increase in sheath length contributed to the increase in proportion of yield above 4 cm. Rate of leaf extension was not closely related to yield and was more sensitive to temperature than was yield. Changes during regrowth in blade and sheath length helped to explain changes in weight per tiller, previously reported. The effects of improving weather conditions in late winter/early spring were similar to the effects of applied N: larger, heavier leaf blades, longer sheaths, a taller canopy, a lower proportion of dead material, younger leaves. The length of shoot apex per leaf primordium was relatively constant. Leaves continued to emerge, at a slow rate, in the period December–February. S. 170 had the biggest leaves, particularly in May, and the slowest rate of leaf turnover. Rate of leaf extension was increased by applied N more, on average, in the ryegrasses than in the fescues.

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