Chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carboxyl]benzenesulfonamide} has recently been registered for the control of several broadleaf weeds in spring wheat (Triticum aestivum L.), durum wheat (Triticum durum Desf.), and barley (Hordeum vulgare L.) in western Canada. Residue carryover of this herbicide can cause injury to subsequent sensitive crops. A bioassay technique based on growth of pregerminated corn roots was used to detect levels of chlorsulfuron as low as 0.125 ppb in three Saskatchewan soils. Confidence levels of 95% were established. These confidence bands allowed the detection of chlorsulfuron levels within a minimum and maximum variation of 3.1 and 11.5% of root development.

No abstract

FosrER, R. K. 1990 MATERIALS AND METHODSThree identical field experiments located on the same site were conducted during 1979-1981, 1980-1982 and 1981-1983

The use of winter legumes in southern Brazil is hindered by the slow growth of these species during establishment exposing soil surface to erosion. Introduction of these species along with spring wheat (Triticum aestivum L.) was studied as a means of increasing ground cover during their initial establishment period, without reducing wheat grain yield. Two experiments were conducted in nearby areas, one in each year. Birdsfoot trefoil (Lotus corniculatus L.), red clover (Trifolium pratense L.) cultivar Quiñequelli, white clover (T. repens L.), and arrowleaf clover (T. vesiculosum Savi) did not reduce cereal yield in either year. Wheat yield was reduced by intercropped red clover cultivar Kenland and by subclover (T. subterraneum L.) in the first year. No grain yield differences due to intercropping with any legume were detected in the second year, when rainfall was below normal. Intercropping with wheat showed to be a practical alternative to enhance ground cover at establishing forage legumes.Index terms: Triticum aestivum, feed crops, soil, plant cover, yield components.Efeito do consórcio entre trigo e leguminosas forrageiras na produção de trigo e na cobertura de solo A consorciação com trigo mostrou-se como uma alternativa prática para aumentar a cobertura de solo no estabelecimento de leguminosas forrageiras.Termos para indexação: Triticum aestivum, plantas forrageiras, solo, cobertura vegetal, componentes do rendimento.

A study was carried out to establish the optimum rates of N and P fertilizers, optimal ratio of basal to top dressed N and time for top dressing the balance of total N in rainfed wheat in the high rainfall zone of northern Zambia. Grain yield, number of spikes per unit area and number of kernels per spike increased with both N and P rates. Except for kernel weight, the other yield components were positively correlated with grain yield. Split application with a ratio favouring top dressing, and applied four weeks after seeding gave higher yields than ratios favouring basal dressing. Initial fertility levels and rainfall distribution influence on the effects of these factors are discussed.

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The recently introduced Canada Prairie Springs (CPS) class of wheat (Triticum aestivum L.), contains semidwarf cultivars that may require different management practices from the traditional Hard Red Spring (HRS) wheats grown in western Canada. This study was conducted to determine if ‘HY320’ CPS and HRS cultivars respond differently to seeding method and N fertilization. Seeding methods involving stubble mulch and clean tillage were applied for a minimum of 3 yr at: Swift Current, Saskatchewan (Sask.) on a Swinton silty loam (Typic Haploboroll); Saskatoon, Sask. on a Bradwell fine sandy loam (Typic Haploboroll); and at Melfort, Sask. on a Melfort silty clay loam (Vertic Haploboroll). Plots were fertilized with 0 to 150 lb N/acre at Melfort and 25 or 50 lb/acre at Saskatoon. Canada Prairie Spring wheat showed a 15 bu/acre yield advantage over HRS wheat when yields exceeded 60 bu/acre. The advantage steadily decreased to 0 bu/acre at yields of 15 bu/acre. Preseeding tillage reduced yields at two out of three sites by 1 to 3 bu/acre. Nitrogen fertilizer up to 50 lb/acre caused yield increases where yield levels were above 40 bu/acre. During dry growing seasons added N gave only modest or no benefits. Grain protein varied with year, location, N rate, and cultivar. Within every site HRS wheat had higher protein than CPS by 1 to 1.4% units. At Melfort in 1988 discer seeding without preseeding tillage had high grain protein compared to the other treatments. The response of HRS and CPS wheats to seeding method is similar and no differences in planting recommendations are justified between them.