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No abstract

Random sets of lines from three durum wheat (Triticum turgidum L.) crosses were developed by single seed descent to study the relationship between yield and the lengths of the vegetative and grain filling periods. The parents of the three crosses, 'Pelissier'/'Hercules', 'Stewart 63'/'Anhinga', and 'Wakooma'/'Anhinga', were selected to represent different combinations of the lengths of the vegetative and filling periods. The random lines were tested in rainfed field experiments in 1982 and irrigated experiments in 1983, and eight characteristics were measured-lengths of the vegetative and filling periods, days to maturity, height, straw strength, yield, weight per I000 kernels, and protein content. The lengths of the vegetative and filling periods were negatively correlated in both years. Correlations between yield and the lengths of the two growth periods were inconsistent and generally fairly small. The data provided no indication that there was an optimum combination of the lengths of the vegetative and filling periods that gave maximum yield. Yield and protein content showed a significant negative correlation in only two of six tests.

Two cultivars of spring wheat, Triticum aestivum L., cvs. ‘Neepawa’ and ‘Pitic 62’, and one cultivar of spring barley, Hordeum vulgare L., cv. ‘Bonanza’, were compared for grain yield and its relationship to patterns of leaf area development and dry matter accumulation. Each cultivar was planted at an early and a late seeding date at Saskatoon in 1980 and in 1981. Leaf area (cm2/plant) and biological yield (g/m2) were determined at weekly intervals commencing five weeks after seeding. Grain yield, components of grain yield, and final biological yield were measured at maturity. Grain yield was found to be a curvilinear function of final biological yield in Pitic 62 and Bonanza but the relationship appeared to be linear for Neepawa. Within a cultivar, higher biological yield gave higher grain yield.Bonanza barley produced more dry matter and greater leaf area than either wheat cultivar early in the season. This advantage disappeared as the crop approached maturity. Pitic 62, although having greater maximum leaf area index and greater leaf area duration than Neepawa, tended to have a similar pattern of dry matter accumulation early in the season. Pitic 62 had greater final biological yield and grain yield by virtue of its later maturity. Yield of wheat might be increased without delaying maturity by searching for types which grow quickly under cool spring conditions.

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