COLD HARDINESS OF WINTER WHEAT TILLERS ACCLIMATED UNDER FIELD CONDITIONS

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

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.


1990 ◽  
Vol 70 (4) ◽  
pp. 1033-1041 ◽  
Author(s):  
J. B. THOMAS ◽  
R. A. BUTTS

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


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.


1990 ◽  
Vol 70 (2) ◽  
pp. 443-454 ◽  
Author(s):  
P. RICHARD HETHERINGTON ◽  
BRYAN D. McKERSIE ◽  
LISA C. KEELER

Two winter wheat (Triticum aestivum L.) cultivars, Fredrick and Norstar, which differ in their winterhardiness potential, were compared with regard to the effects of nitrogen (N), phosphorus (P) and potassium (K) application, during acclimation, on the expression of four traits associated with winterhardiness — freezing, ice-encasement, and low temperature flooding tolerances and crown moisture content. Modified Hoagland’s nutrient solutions containing five levels of each nutrient were applied to the seedlings during a 5-wk acclimation period at 2 °C, and subsequently the crowns were tested for their ability to survive varying intensities of the stress treatments. Increasing the level of applied N from 0, caused a reduction in the level of all stress tolerances. Increased P did not significantly alter the expression of freezing tolerance, but tended to increase tolerance of the anaerobic stresses, icing and low temperature flooding, to an optimum. Increased K had minimal effects on stress tolerance at the levels tested. Increased levels of each nutrient increased crown moisture content. The cultivar Norstar was consistently more tolerant of freezing and icing stress than Fredrick and this relative ranking was not influenced by mineral nutrition. However, the relative ranking for low temperature flooding tolerance varied depending on the nutrients provided to the seedlings. The results suggest that environmental and growth regulatory factors which influence the uptake of mineral nutrients would be expected to influence crown moisture content, and the expression of stress tolerance.Key words: Freezing, ice-encasement, flooding


1988 ◽  
Vol 68 (2) ◽  
pp. 301-309 ◽  
Author(s):  
D. J. GILLILAND ◽  
D. B. FOWLER

In the northern part of the North American Great Plains, the level of cultivar winter-hardiness required for winter wheat (Triticum aestivum L.) production is extremely high. Presently, available winter wheat cultivars with adequate winterhardiness are tall and, under favourable growing conditions, crop lodging and excessive amounts of straw can present serious production problems. Consequently, cultivars with short, stiff straw and a high harvest index would be desirable for high production areas within this region. However, semidwarf cultivars with superior winterhardiness have not yet been developed. In this study, six GA-insensitive (Rht) semidwarf parents with poor to moderate winterhardiness were crossed with three GA-sensitive (rht) tall parents possessing good winterhardiness to produce 20 different single, three-way and double crosses. These crosses were evaluated to determine if the GA-insensitive character could be combined with a high level of winterhardiness in winter wheat. Gibberellic acid (GA) sensitivity analyses of F2 seedlings established that a single GA-insensitive gene was involved in each cross. F2-derived F3 and F3-derived F4 lines were assessed for GA-sensitivity and winterhardiness levels were determined from field survival at several locations in Saskatchewan, Canada. Winter survival of homozygous GA-sensitive and GA-insensitive lines were similar in both generations. Lines with winterhardiness levels similar to those of the three tall parent cultivars were recovered in all GA-response classes. The absence of a meaningful pleiotropic effect of Rht genes on winterhardiness indicates that the reason semidwarf cultivars with superior winterhardiness levels have not been developed is due to the lack of a concentrated breeding effort to combine the two characters. A breeding strategy for the production of adapted winterhardy semidwarf winter wheat cultivars is discussed. The influence of endogenous gibberellin levels on cold hardiness in winter wheat is also considered.Key words: Cold hardiness, field survival, Triticum aestivum L, semidwarf, Gibberellic acid


1985 ◽  
Vol 65 (4) ◽  
pp. 893-900 ◽  
Author(s):  
D. W. A. ROBERTS

Nine cultivars of common wheat (Triticum aestivum L.) ranging from very cold hardy to tender were sprouted in vermiculite at 0.5–1.0 °C for 7 wk in the dark and then placed at 0.5 °C, −2.5 °C, −5 °C, −7.5 °C, or −10 °C for up to 20 wk. Plants held at 0.5 °C progressively lost hardiness. Little change occurred in the hardiness of plants moved to −2.5 °C. There was apparently a small initial increase in hardiness after transfer to −5 °C or −7.5 °C followed by a decline in hardiness. Plants transferred to −10 °C lost hardiness progressively after transfer. These results suggest that part of the reason for late-winter mortality of winter wheats in northern regions of the Canadian prairies is damage from long exposures to temperatures only slightly lower than −5 °C. This damage is manifested by higher LT50 values or lower cold hardiness in late winter and early spring.Key words: Triticum aestivum L., cold hardiness, winter survival


2010 ◽  
Vol 90 (6) ◽  
pp. 919-924
Author(s):  
G.C. Wilson ◽  
N. Soltani ◽  
C.J. Swanton ◽  
F.J. Tardif ◽  
D.E. Robinson ◽  
...  

Volunteer winter wheat (Triticum aestivum L.) is a sporadic weed found in corn (Zea mays L.) fields across southern Ontario. Eight trials were conducted over a 2-yr period (2006 and 2007) at four locations to determine the competitiveness of volunteer winter wheat in corn. A soft red winter wheat cultivar (Pioneer 25R47) was seeded at each location at densities of 0 to 30 seeds m-2 late in the fall, prior to corn planting the following spring. Volunteer wheat competition in corn resulted in reduced emergence of corn leaf collars. Competition with volunteer wheat resulted in a 5% decrease in corn leaf collars present at 21 and 70 d after emergence with volunteer wheat densities of 3.0 and 5.2 plants m-2, respectively. Furthermore, volunteer wheat competition reduced total leaf area, leaf dry weight, shoot dry weight, plant and ear height and yield by 5% with densities of 5.1 to 6.0 plants m-2 compared with the weed-free control. The level of competitiveness was dependent on the density of volunteer wheat.


1984 ◽  
Vol 62 (4) ◽  
pp. 818-822 ◽  
Author(s):  
D. W. A. Roberts

Young plants of the cold-hardy winter wheat (Triticum aestivum L. emend. Thell.) Kharkov 22 MC did not develop atypical prostrate or rosette growth habit unless light supply exceeded 350 klux∙h∙day−1. Prostrate habit developed under both short (10-h) and long (16-h or 24-h) photoperiods. Under a given photoperiod, expression of this trait intensified as light intensities increased. This finding was demonstrated in both field and growth-cabinet experiments. The degree of development of the rosette growth habit may be assessed by plotting plant height against plant age. Plants that develop typical rosettes decline in height when the rosettes develop whereas plants that remain erect show a continuous increase in height.


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.


2013 ◽  
Vol 66 (2) ◽  
pp. 137-148
Author(s):  
Elżbieta Harasim ◽  
Marian Wesołowski

<p>A field study was conducted in the period 2004–2007 on grey-brown podzolic soil (sandy). This study analysed the relationship between the use of stem shortening in cereals by means of retardants with the following active substances: chlormequat chloride (Antywylegacz Płynny 675 SL), trinexapac-ethyl (Moddus 250 EC), chlormequat chloride + ethephon (Cecefon 465 SL), and weed infestation. The retardants were applied at the 1st node stage (BBCH 31 – Antywylegacz Płynny 675 SL) and the 2nd node stage of winter wheat (BBCH 32 – Moddus 250 EC and Cecefon 465 SL), together with the adjuvant Atpolan 80 EC (75% of SN 200 mineral oil) or without the adjuvant. Winter wheat, cv. 'Muza', was grown after vetch grown for seed. The whole experiment was sprayed with the herbicides Apyros 75 WG and Starane 250 EC at the full tillering stage (BBCH 29–30). Plots where no growth regulators were used were the control treatment.</p><p>Weed density and biomass showed great variation between years. In the winter wheat crop, <em>Veronica persica, Viola arvensis, Veronica arvensis, Capsella bursa-pastoris</em>,and<em> Chenopodium album </em>dominated in the dicotyledonous class, whereas <em>Apera spica-venti</em>, <em>Echinochloa crus-galli</em>,and<em> Elymus repens </em>were predominant among monocotyledonous plants<em>. </em>The level of weed infestation of the winter wheat crop, as measured by the number and air-dry weight of weeds, was significantly differentiated by years and retardants used as well as by interactions of these factors. The adjuvant Atpolan 80 EC did not have a significant effect on the above-mentioned weed infestation parameters.</p>.


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