Inheritance of adult plant resistance to powdery mildew in swedes

Abstract

A complete diallel set of crosses, including selfs, was produced from 11 inbred lines of swedes and assessed for adult plant resistance to powdery mildew in a replicated field trial. The plants were inoculated with powdery mildew spores on 23 July 1987. Traces of mildew were visible on 3 August. By 14 September the most susceptible inbred line had 95% of its leaf area infected, whereas the three most resistant lines derived from cvs Bangholm Dima (two lines) and Bangholm Magres (one line) had only 5%. Resistance was controlled by partially recessive genes. There was no evidence of maternal effects. The implications for breeding inbred and F, hybrid swede cultivars are discussed.

Single seed descent as a breeding method for swedes (Brassica napus L. var. napobrassica Peterm)

“…Two of the hybrids involved four different sources of turnip root fly resistance, and the third hybrid had one parent which was thought to be homozygous for a major dominant gene for resistance to turnip mosaic virus (Bradshaw et al 1989b). Subsequently it was decided to concentrate selection on resistance to clubroot and powdery mildew, as these were the two major disease problems of swedes, as well as on yield and quality traits.…”

“…Parents for second SSD breeding programme Sixteen parents (13 cultivars or potential cultivars and 3 F 1 hybrids) were chosen from SCRI's germplasm collection for their yield and quality traits and as sources of resistance to clubroot, powdery mildew, turnip mosaic virus and turnip root fly (Delia floralis Fallen) (Bradshaw et al 1989b). Two of the hybrids involved four different sources of turnip root fly resistance, and the third hybrid had one parent which was thought to be homozygous for a major dominant gene for resistance to turnip mosaic virus (Bradshaw et al 1989b).…”

“…Swedes for early autumn use tend to have low DM concentrations whereas those with winter hardiness have higher contents (Davey 1946). Resistance to clubroot (Plasmodiophora brassicae Woronin) (Bradshaw et al 1997) and to powdery mildew (Erysiphe cruciferarum Opiz ex L. Junell) (Bradshaw et al 1989a) is highly desirable in all types of swede.…”

Swedes and Turnips

“…The inheritance of mildew resistance was studied by Bradshaw et al (1989) from a diallel cross of 11 inbred lines, chosen to include the most resistant and susceptible parents. The most resistant parents were from cultivars 'Bangholm Dima' and 'Bangholn Magres.'…”

Swede and turnip

“…Both turnip and swede suffer from a large number of pests and diseases, 1 many of which are common to other Brassica crops (see Chapters 3,9,10,12,17,18). For many of these, growers have to rely upon chemical methods of control; however, host resistance is available for some of the major pests and diseases.…”