Management of winter wheat (Triticum aestivum L.) should include N fertilization, crop protection, and seeding rates that allow efficient production based on cultivar and environmental yield potential. These studies were conducted to evaluate regionally grown cultivar responses to crop management systems in northern Idaho. In three environments, four cultivars were grown using management treatments (MT) similar to current recommended practices (MT3); a treatment with conservative N fertilization (MT2); a low input treatment with lower N, lower seeding rate, and minimal herbicide (MT1); and a high input treatment with higher N with split applications, plus a fungicide and growth regulator application (MT4). Data on grain yield, protein, test weight,plant height, and lodging were collected in all studies. In the two studies in 1992, leaf tissue N and soil N were analyzed and yield components were determined. Environment x MT and enviroment x cultivar interactions were found for grain yield, test weight, and protein. In 1991 at Moscow, the hard red wheat' Weston' produced the highest grain yields across MTs and was the only cultivar to produce highest yields with MT4. Also in that environment, the three soft white cultivars produced higher yield andtest weight and lower protein in MT2 than in MT3. In 1992 at Potlatch, limited soil water restricted yield, and MT1 had lower yields than other MTs, but protein content increased with higher N fertility. At Moscow in 1992, agronomic performance appearsbetter in MT1 than in other treatments due to abundant early vegetative growth in the higher N fertility treatments that was followed by a soil water deficit throughout reproductive stages. Weston produced the lowest yield, heads per acre, and kernels per head at Moscow in 1992, but was highest in test weight, grain protein, and plant height. At both sites in 1992, yield components were positively correlated to yield, indicating treatment differences were influencing yield throughout several plant growth stages. High inputs (MT4) can be beneficial under some circumstances, but conservative N fertilization with conventional practices (MT2) gave the best overall agronomic performance across the tested environments and cultivars.
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