The diversity of head-scab resistance in Triticeae and their relation to ecological conditions
Abstract1507 accessions from 93 species of 18 genera in Triticeae were screened for resistance to initial infection and resistance to pathogen spread with multi-floret and single-floret injection inoculation methods respectively. The accessions with high resistance were mainly found in perennial genera: Roegneria, Hystrix, Agropyron, Kengyilia and Elymus. Based on differences in resistance, 18 genera screened in Triticeae could be classified into five groups. The species with high resistance were mainly distributed in humid ecological environments.
Controlling fusarium head blight of wheat (Triticum aestivum L.) with genetics
Fusarium head blight, one of the most destructive diseases of wheat (Triticum aestivum L.), results in significant economic losses from reduced grain yield and quality. In recent decades, the disease has been frequently recorded, especially under warm and wet climatic conditions. Genetic resistance has engaged plant breeders because the use of resistant cultivars is the most economical, effective, and environmentally friendly method of control. In the present paper, we summarize the research on resistance genetics of Fusarium head blight, suggest a new method for evaluating Fusarium head blight resistance, and recommend strategies for creating and developing new sources of resistance to Fusarium head blight through the use of alien genes and chromosomal segments.
Effect of Soybean Cyst Nematode (Heterodera glycines) on Yield of Resistant and Susceptible Soybean Cultivars Grown in Ohio.
Soybean (Glycine max) producers in Ohio rarely use soybean cyst nematode (Heterodera glycines, SCN)-resistant cultivars because of concerns over limited yield potential and lack of resistance to Phytophthora sojae. A two-year study was initiated to determine grain yield and nematode population increase on soybean cyst nematode-resistant cultivars in maturity groups II and III in production fields. Sites differed in soil texture, nematode densities, and P. sojae infestation at a number of locations in Ohio. Soil was assayed for nematode densities before planting and at harvest. Yields of resistant cultivars averaged 0% to 18% higher than those of susceptible cultivars in fine-textured soils with average preplant populations ranging from 463 to 14,330 SCN eggs/100 cm(3) soil. In coarse-textured soils, yields of susceptible cultivars were 21% to 56% less than the resistant cultivars with average preplant densities ranging from 1,661 to 15,558 SCN eggs/100 cm(3) soil. The reproductive index ranged from 0.1 to 5.5 for resistant cultivars and 0.4 to 112 for susceptible cultivars. In 1993, yield of P. sojae-susceptible, nematode-resistant 'Asgrow A 3431' was as high as yield of the P. sojae-resistant, nematode-susceptible cultivar 'Resnik' in a Phytophthora-infested field. The nematode-resistant cultivars Madison Experimental 131527 and Asgrow A3431 had higher yields than AgVenture AV1341 and susceptible cultivars Resnik and Kenwood when compared over five nematode-infested sites. Nematode-resistant cultivars were found to be excellent alternatives to currently grown susceptible cultivars for managing SCN where group III cultivars are used. However, better cultivar alternatives may be needed for sites with combined Phytophthora root rot and cyst nematode problems.