Inbred line versus F_t hybrid breeding in swedes (Brassica napus L. var. napobrassica Peterm)

Abstract

In 1989 seven F, hybrid swedes were produced in polythene tunnels. The female parent was an inbred line derived from cv. Ruta Otofte, and made selfincompatible with an S-allele introduced by backcrossing. Three more hybrids were produced in 1990 in a similar way with an inbred line from cv. Criffel as female parent. In trials in Dundee over the period 1990 to 1992, better parent heterosis for dry matter yield in the hybrids ranged from 1.9% to 19.2%. There was no such heterosis for dry matter percentage nor for mildew resistance.The highest yielding hybrid was the one between the Criffel line and an inbred line from cv. Magres. It averaged 9.9% heterosis over the two years 1991 and 1992, outyielded seven commercial cultivars, but had a lower yield (12.3 t/ha) than an F6 line SS5 (13.3 t/ha) derived from the cross between the Criffel and Magres lines by pedigree inbreeding with selection.It is concluded that high yielding heterotic F,'s should be the starting point rather than the finishing point of swede breeding programmes, and that research into breeding methods should concentrate on improving the efficiency of pedigree inbreeding following hybridisations, rather than on ways of producing F, hybrids.

Combining Ability Analysis and Genetic-Effects Studies for Some Important Quality Characters in Brassica napus L.

“…Bradshaw and Wilson (1998) established significant results in inbred lines of brassica for glucosinolate concentration. On the other hand, parents vs. crosses showed non-significant variation.…”

Swedes and Turnips

“…The resources put into the production of one cultivar 'Kenmore' were (Bradshaw and Wilson, 1993): Alpha designs (Patterson et al, 1978) were used to grow and analyze the early generation trials, as this was considered the best statistical method available for the large number of plots involved.…”

“…In turn, the cultivars listed in the 1980s and early 1990s (Angus, Melfort, Angela, Airlie, and Ruby) showed a further 8% improvement on RutaǾtofte, Marian, and Magres (1993 NIAB Recommended List). Cultivar Kenmore, National Listed in 1994, is the highest yielding Scottish one to date (Bradshaw and Wilson, 1993;Bradshaw et al, 2009) (Table 8.1).…”

“…When potential swede cultivars are assessed in yield trials, multiple-row plots are used and the outside rows discarded in order to minimize competition effects between cultivars in adjacent plots (Kimber, 1977). This is common practice in yield trials of crop plants but is not always possible in the early stages of a breeding program (Bradshaw and Wilson, 1993). A uniformity trial (Gowers, 1976) showed that a plot size of 4 rows by 10 m was a good compromise between area of trial and low coefficient of variation (COV).…”

“…A range of SI lines was obtained from various sources, and the origins of 19 lines are given in Gemmell et al (1989); all types of dominance relationships were found within these lines (Gowers, 1989). As selfincompatibility (SI) is dominant to self-compatibility (SC), its backcrossing into agronomically desirable inbred lines of swedes with good combining ability was straightforward but laborious (Bradshaw and Wilson, 1993).…”