MANAGEMENT EFFECTS ON YIELD AND ABOVEGROUND BIOMASS OF 3 SPRING WHEAT CULTIVARS

Although bioclimatic conditions of the Saint Lawrence Lowlands are generally good enough to grow wheat for bread, management of this wheat production is poorly known in Quebec. Yields and total above-ground dry-matter biomass of three spring wheat (Triticum aestivum L.) cultivars (Max, Columbus and Katepwa) were measured in 1991 and 1992 under three management systems on a clay loam soil of the Saint Lawrence Lowlands. Reduced (50 kg N ha(-1) and 375 plants m(-2)), conventional (100 kg N ha(-1) and 375 plants m(-2)) and intensive (150 kg N ha(-1) and 450 plants m(-2)) management systems were compared. In 1991, significant differences were observed among cultivars for four variables: stem weight, harvest index, tillers per square metre, and 1000-kernel weight. The management effect is less important than the cultivar effect. In 1992, significant differences among cultivars were observed for six of the nine variables measured, and seven of the nine variables measured differed with management. No significant cultivar x management interactions were observed in either year. Increasing input levels did not increase yield in 1991, probably because of the drier conditions. In the cooler and rainy growing season of 1992, intensive management increased wheat yield compared with that of reduced and conventional management. In both years, grain yield under reduced management was not significantly different from that under conventional management. Grain yield under intensive management was significantly higher than under reduced and conventional management in 1992 but not in 1991. The results of this study did not clearly show that intensive management was really better in the climatic conditions of the Saint Lawrence Lowlands than conventional or reduced management.