PLANTING DATES AND SEEDING RATES FOR SOFT WHITE WINTER-WHEAT IN EASTERN ONTARIO

A study was made to determine optimum fall planting dates and rates of seeding of soft white winter wheat (Triticum aestivum L.) in three counties in eastern Ontario. This area is considered marginal for winter survival of the crop, although yield potential is high. Plots were sown at Douglas (lat. 45-degrees-33'), Ottawa (lat. 45-degrees-23') and Kemptville (lat. 45-degrees-00'). Four planting dates were used at Douglas and Ottawa (dates 1 to 4) and five dates at Kemptville. These were: date 1, 27 August; date 2, 10 September; date 3, 24 September; date 4, 8 October; and date 5, 22 October. Split-plot designs were used, with dates as main plots and with rates and cultivars randomized as subplots. Harvest years were between 1983 and 1987. Winter survival was generally reduced below 60% in later plantings. but survival remained high from the date 4 planting in two years at Ottawa. Grain yields were increased by early plantings. Maximum yields at Douglas were obtained from dates 1 and 2; at Ottawa and Kemptville, from dates 1 to 3. A significant advantage of date 2 planting was recorded at Kemptville. Kernel weight and test weight were reduced by late planting dates. Grain yields and winter survival were highly correlated at seven of nine location-years. At Ottawa, there was a significant yield increase from the 160 kg ha-1 seeding rate, compared with 130 kg ha-1, the currently recommended rate. Yield increases from higher seeding rates were greater at later planting dates. Cultivar effects on grain yields were frequently significant, but were less so on winter survival. The cultivar Houser produced the highest yield in five of nine location-years.