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Current western Canadian hard red spring wheat cultivars and their progenitors, inoculated with a composite of Tilletia tritici and T. laevis races, were grown at Lethbridge from 1989 to 1991 and the percentage infection was determined. This study also examined cultivar × environment interaction effects. Ancestral cultivars, such as Red Calcutta 33, Marquis, Thatcher, and their descendants, Canthatch, Park, Neepawa, Manitou, and Cadet, exhibited intermediate levels of bunt resistance. Cultivars including the cultivar Hope in their ancestry, such as Redman, Chris, Katepwa, Columbus, Reward, and Lancer, were highly resistant. Analysis of the environment × cultivar interaction indicated that bunt infection levels in Hope, Redman, and Columbus were stable over environments, but infection which varied according to environment was observed for Katepwa and Reward. The reduction of a number of cultivars including Neepawa, Thatcher, Kenya Farmer, Fortuna, Cadet, and Chris, was unstable across environment. Mexican semi-dwarf cultivars, such as Tobari 66, Potem 70, Cajeme 71, Ciano 67, Sonora 64, Inia 66, and the Canadian cultivars HY320, BW 90, and Laura, were highly susceptible. In general, the level of infection in these cultivars was uniform across environments. The nature of resistance in Canadian cultivars, the high infection levels of some Canadian cultivars and their Mexican semi-dwarf ancestors, and the variation in stability of infection levels of some cultivars across environments are discussed. Key words: Triticum aestivum, semi-dwarf, stability analysis, genotype × environment interactions

No abstract

The RAPD procedure was used to establish genetic diversity of 28 potato genotypes including siblings and genotypes with no immediate relationship. In addition amplified DNA from three parents and Solanum chacoense were compared with that from six progeny to determine the genetic relationships. Amplification of genomic DNA from the 28 genotypes using PCR and 12 decamer primers yielded 158 amplified DNA fragments, ranging in size from 490 to 3200 bp. A total of 128 unique RAPD fragments were observed among the 28 potato genotypes. Similarity measures and principal coordinate analysis generally reflected the expected trends in relationships of the full and half-sib potato genotypes. However there were important exceptions to this general trend and it appears that related varieties can be as genetically different as varieties with no immediate relationship. The data suggest that RAPD analysis used in conjunction with pedigree information can provide a superior measure of genetic divergence than analysis based solely on pedigree information.

The putative yield advantage associated with growing upright beans (Phaseohs vulgaris L.) at high planting densities in narrow (0.23-m) rows might he compromised by a higher risk of white mold [Sclerotinia sclerotiorum (Lib.) de Bary] because of reduced air flow through the crop canopy. This four-yeai-study was undertaken to compare the white-mold avoidance and agronomic attributes of upright bean lines and to determine whether their yields can he increased by raising planting density. Four upright lines and a viny line as a control were established in narrow rows at planting densities ranging from 25 to 60 plants/m* in a field artificially infested with sclerotia of S. sclerotiorum. On average, the four upright lines had lower incidence of white mold and smaller disease severity indices than the control, `UI36', indicating that the development of white mold is reduced in dense, erect canopies. There were differences in disease response among the upright lines, with `ISB82865' and `UI906' being the least and most susceptible entries, respectively. Increases in planting densities resulted in higher yields and influenced the development of white mold hut had no effect on vine length, lodging, and maturity. However, the planting density effect on the disease response was not consistent among entries in 2 of the 4 years. The results of this study indicate that upright beans can he grown at high planting densities without greatly increasing the risk of a white-mold outbreak. The choice of the most appropriate planting density for upright beans depends largely on the cost of seed.