THE RESPONSE OF FALL-SOWN CEREALS TO WINTER STRESSES IN EASTERN ONTARIO

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Abstract
A study was made from 1979 to 1982 of the overwintering capacity of winter cereals at six sites in eastern Ontario outside the traditional winter wheat growing area. Cultivars of soft white, soft and hard red wheats, a rye and a triticale were compared for winter survival in the field, cold hardiness and ice tolerance of plants removed from the field in winter, and grain yield. Overall mean grain yield of four wheats was the equivalent of 3980 kg/ha with a high mean yield of Houser in 1982 of 5035 kg/ha. In 3 yr good survival and yields were obtained with a range of cultivars, while in the fourth year only the hardiest cultivars survived well at most sites. Survival was reduced at one site in all 4 yr by snow mold. There were significant cultivar × site interactions in winter survival in 3 of the 4 yr. Fall-developed cold hardiness showed significant differences between sites and between cultivars with site means ranging from LD50 values of −20.6 °C to −10.2 °C. There were major differences in cold hardiness and ice tolerance of field-grown plants of 23 cultivars at Ottawa in 1981, but correlations between the two parameters were not significant. Ice tolerance in winter 1982 showed significant differences between sites and between cultivars. Winter survival and cold hardiness were significantly correlated at two of the five sites in 1982 — the most stressful winter season. Overall, Norstar, the highest winter survivor of the wheats, was frequently the lowest yielder. The red wheats Lennox and Valor showed consistenty high cold hardiness and winter survival accompanied by good yields, while of the soft white wheats, Houser showed frequent superiority in cold hardiness, and inconsistent advantages in winter survival and yield.Key words: Wheat (winter), winter injury, survival, cold hardiness, ice