CONTENT AND UPTAKE OF PHOSPHORUS AND COPPER BY SPRING WHEAT - EFFECT OF ENVIRONMENT, GENOTYPE, AND MANAGEMENT

Copper (Cu) deficiency in grain crops grown on the Canadian Prairie ha s increased recently, while nearly 50% of the soils have low available phosphorus (P) levels. This study was conducted to quantify the varia tion in Cu and P uptake among some common Canadian wheat (Triticum aes tivum L.) cultivars due to the effects of nitrogen (N) fertilizer and the environment. The effects of N fertilizer application at 0, 50, and 100 kg N ha(-1) and seeding in early May or mid-May on the P and Cu c ontents of four wheat cultivars were determined in an experiment condu cted over two years at Fort Vermilion (58 degrees 24'N, 116 degrees 0' W). Cultivar and N fertilizer produced similar variances in P concentr ation. Phosphorus uptake was increased by N fertilizer, but was not af fected by the cultivars tested. Nitrogen fertilizer produced four time s as much variability in Cu concentration and uptake as did the effect of genotypes. Date of sowing within the recommended time frame had no effect on plant P and Cu contents. There was no treatment interaction effect on plant P or Cu content. Tn a second experiment, situated nea r Grande Prairie (55 degrees 10'N, 118 degrees 48'W) and conducted ove r two years, P and Cu uptake and concentrations were determined for 10 agronomically diverse spring wheat cultivars. The range was 1.2- to 1 .4-fold for P and 1.5- to 1.7-fold for Cu concentration. Plant Cu, but not plant P, was correlated with grain yield (r=0.64 to 0.86), sugges ting that either varietal differences in Cu uptake may affect yield or prior selection for yield may have resulted in the selection for Cu-e fficient plants as well. Environmental, i.e., site-year, effects on pl ant P, and particularly Cu concentrations, were larger than the variet al effects in both studies. These studies indicate that selection of C anadian wheat cultivars should be based on their yield potential rathe r than their efficiency in Cu or P uptake since crop nutrition can be more readily managed by optimal fertilization.