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

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.

1977 ◽  
Vol 57 (3) ◽  
pp. 751-755 ◽  
Author(s):  
D. B. FOWLER ◽  
L. V. GUSTA

Changes in number of coleoptile tillers, plant height, leaves per plant, degree of vernalization, cold tolerance (LT50) and several measurements made on the plant crown were determined for winter rye (Secale cereale L.) and winter wheat (Triticum aestivum L.) cultivars grown under field conditions in the fall of 1972 and 1973 at Saskatoon. Measurements made on the crown included fresh weight, dry weight, water content, depth, root number, root length and number of tillers. Years, dates of seeding and time of sampling had a significant influence on most variables. Correlations based on developmental differences for the acclimation period were significant for all variables measured. Dry weight was most closely related to LT50, and regression analyses indicated that the remaining variables did not explain any additional variability in LT50. Cultivar differences were apparent for most variables studied; however, these differences often did not reflect differences in field survival potential.


1983 ◽  
Vol 63 (4) ◽  
pp. 879-888 ◽  
Author(s):  
W. G. LEGGE ◽  
D. B. FOWLER ◽  
L. V. GUSTA

The cold hardiness of tillers separated from the plant immediately before freezing (CTM) or left intact on the crown (ICM) was determined by artificial freeze tests on two sampling dates for four winter wheat (Triticum aestivum L.) cultivars acclimated in the field. Plants with 9 and 13 tillers excluding coleoptile tillers were selected in mid-October and at the end of October, respectively. No differences in lethal dose temperature (LT50) were detected among CTM or ICM tillers sampled in mid-October. The three youngest CTM tillers sampled at the end of October were less cold hardy than older tillers. However, younger CTM tillers did not survive the unfrozen control treatment as well as older tillers. ICM tillers sampled at the end of October had the same LT50 except for one of the older tillers. No correlation was found between either the moisture content or dry weight and the LT50 of tillers. Winter survival of tillers was evaluated for two cultivars in the spring. Tillers of intermediate age and two of the youngest tillers had the highest survival rates. Tiller regeneration from axillary buds rather than the apical meristem occurred following cold stress and was negatively correlated to tiller emergence date. It was concluded that differences in cold hardiness among tillers must be taken into consideration if tillers are utilized to estimate the LT50 of a plant.Key words: Cold hardiness, tillers, winter wheat, Triticum aestivum L., developmental stage, moisture content


1976 ◽  
Vol 56 (4) ◽  
pp. 775-779 ◽  
Author(s):  
L. V. GUSTA ◽  
D. B. FOWLER

Crowns of winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) collected early in the spring readily dehardened upon exposure to 15 C. After 6 days at 15 C, the crowns of both species were completely dehardened. Partially dehardened crowns were unable to reharden upon exposure to cold-acclimating conditions and continued to lose hardiness when stored at − 2.5 C. There was a positive correlation between level of dehardening and crown moisture content. However, this relationship began to break down when attempts were made to reharden partially dehardened plants.


1978 ◽  
Vol 58 (4) ◽  
pp. 917-921 ◽  
Author(s):  
S. FREYMAN

Two winter wheat (Triticum aestivum L.) cultivars, Kharkov 22 MC and Winalta, were grown for 14 or 28 days under controlled environment from large or small seed or from seed with about half the endosperm removed. The kernels were seeded either 1 or 5 cm deep. After a 14-day cold hardening period followed by a freezing test, plants that had grown actively for 28 days were hardier than those that had grown actively for only 14 days. Plants from large kernels were hardier than those from small kernels, which in turn were slightly hardier than those from kernels with half the endosperm removed. Deep seeding reduced cold hardiness. The treatments had a marked effect on the dry weight of crowns and a smaller effect on crown total available carbohydrate content, both of which were positively correlated with cold hardiness, whereas water content was negatively correlated with cold hardiness.


1976 ◽  
Vol 56 (3) ◽  
pp. 673-678 ◽  
Author(s):  
L. V. GUSTA ◽  
D. B. FOWLER

Cold-hardened crowns of winter wheat (Triticum aestivum L.) and a winter rye (Secale cereale L.) readily dehardened upon exposure to warm temperatures. Crowns dehardened at a faster rate at 20 C than at 10 and 15 C. Dehardened plants were capable of rehardening in a short period of time upon exposure to cold-acclimating conditions. In all the dehardening studies, there was a high positive correlation between cold survival and water content of the crowns. Plants collected in the fall and stored at −2.5 C maintained the same level of hardiness for 17 wk.


1986 ◽  
Vol 66 (3) ◽  
pp. 553-557 ◽  
Author(s):  
D. B. FOWLER

Winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) were seeded into stubble the first week of September and October on four different years at a total of 11 sites in the central, eastern and northern part of the agricultural region of Saskatchewan. The average response to delayed seeding was a reduction in yield and hectolitre weight for both species. In contrast, date of seeding did not have a large influence on kernel size. A significant environmental effect was observed for all characters measured. Productivity of both wheat and rye was high when moisture conditions were adequate. Average yield of rye was higher and 1000-kernel and hectolitre weight lower than for wheat. Significant first and second order interactions demonstrated that the effects of seeding date, species and environment were not independent. These interactions were of sufficient magnitude to introduce a risk factor which should be taken into consideration when conclusions are drawn on the influence of seeding date on yield and other agronomic characters of stubble-seeded winter cereals.Key words: Triticum aestivum L., Secale cereale L., yield, hectolitre weight, kernel size, seeding date


1991 ◽  
Vol 71 (2) ◽  
pp. 565-569 ◽  
Author(s):  
B. J. O'Connor ◽  
L. V. Gusta ◽  
S. P. Paquette

The freezing tolerance of downy (Bromus tectorum L.) and Japanese (Bromus japonicus) brome were compared to Norstar winter wheat (Triticum aestivum L.) collected from similar sites. From December to April of 1987 downy brome was either equal to or superior in freezing tolerance to the winter wheat. Of the three species, Japanese brome was slightly less hardy in December but was of equal freezing tolerance in March and April. There was no correlation between freezing tolerance and tissue water content or tissue dry weight in the three species. These two bromes may become a serious weed in winter wheat because their cold hardiness is either equal or superior to our hardiest winter wheat cultivars. Key words: Downy brome, Japanese brome, winter wheat, freezing tolerance


1981 ◽  
Vol 59 (9) ◽  
pp. 1717-1721 ◽  
Author(s):  
N. J. Tyler ◽  
L. V. Gusta ◽  
D. B. Fowler

Crowns of winter wheat plants water stressed with polyethylene glycol (PEG) (molecular weight 20 000) prior to hardening were more cold hardy than tender crowns or crowns hardened for 2 days (p ≤ 0.05). After 16 days of hardening, plants from all treatments reached the same level of hardiness. Winter wheat crowns water stressed with PEG (210 g/L) for either 0,5, or 21 days reached the same level of hardiness after 2 days of acclimation. In both short- and long-term stress studies, the crown moisture content of the stressed plants was lower (p ≤ 0.05) than that of the controls prior to acclimation. With increasing hardiness both leaf osmotic potential and crown moisture content decreased (p ≤ 0.05). Short-term water stress also resulted in an increase in sugars, specifically sucrose (p ≤ 0.05) prior to cold hardening. However the total sugar content did not parallel the increase in hardiness.Changes in several metabolic parameters were also considered. Significant correlations were found in both studies between the LT50 and osmotic potential, moisture content, and dry weight. Most of the variability in LT50 could be explained by changes in leaf osmotic potential and crown moisture content.


1987 ◽  
Vol 67 (4) ◽  
pp. 1111-1115 ◽  
Author(s):  
A. E. LIMIN ◽  
D. B. FOWLER

Cold hardiness ratings of 18 forage grass species, and cold hardy reference cultivars of winter wheat (Triticum aestivum L. ’Norstar’) and rye (Secale cereale L. ’Puma’), were compared to provide estimates of the winterkill risk for forage grasses established in the spring and fall on the Canadian prairies.Key words: Forage grasses, cold hardiness, seeding date, winter survival


1979 ◽  
Vol 59 (3) ◽  
pp. 853-855 ◽  
Author(s):  
S. FREYMAN ◽  
M. S. KALDY

In two controlled-environment experiments, N fertilizer applied to a Dark Brown prairie soil decreased cold hardiness of winter wheat (Triticum aestivum L.), while P applied in the absence of N had little effect. When applied together, P counteracted the effect of N and produced plants as hardy as those that had received no fertilizer. The soil was rich in K; consequently application of additional amounts of this element had no effect on cold hardiness. The correlation coefficient between dry weight of crowns and cold hardiness (LT50) was not sigificant, but that between water content and LT50 was highly significant.


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