Turnip (Brassica rapa L. ssp. rapifera Metzg.) population improvement and cultivar production

Abstract

In 1977, a fodder turnip breeding programme was started from seven cultivars with the primary aim of increasing dry-matter yield. The breeding method chosen was population improvement by half-sib family selection on a biennial cycle. Seed production in polythene tunnels with blowflies as pollinators was followed by assessing the resulting progenies in replicated yield trials and observation plots from which plants were selected for the next cycle. Six generations of selection resulted in a population with a yield that was 25% higher than the mean of the initial seven cultivars. This was remarkably close to the predicted superiority of the population, despite a significant discrepancy in one generation. It is concluded that the greatest response to selection per year would be achieved by selecting eight families from 128 assessed for 1 year in trials at two or three sites with an overall total of six replicates, given a resource limit of 800 plots.

Swedes and Turnips

“…While having levels of dry rot and clubroot resistance similar to 'Tina,' 'Winton' produced over 30% higher bulb and total dry weight yield than 'Tina' and the four old cultivars in trial. The only winter hardy, Scottish-type turnip produced for many years is the cultivar 'Massif' (Bradshaw et al, 2002). Starting from seven selected cultivars, the program was based on half-sib family selection on a biennial cycle.…”

Genetic diversity based on SSR markers, heterosis and yield performance of Brassica rapa for biomass production

“…The variance of general combining ability of half-sibs is mostly small because pollen movement is not controlled and only between family variations is utilized (Aastveit and Aastveit 1990). Half-sib family selection is simple and has been used in population improvement of B. rapa (Bradshaw et al 2002) In full-sib, crosses between two plants are produced and evaluated. Based on results of progeny evaluation, the high yielding full-sibs seed are sown and used for the next generation.…”

“…Heterosis for grain yield of B. rapa has been reported to be much higher with 18 % MPH for seed yield observed in inter-varietal hybrids (Schuler et al 1992), 25% for dry matter yield in turnip B. rapa after six generations of cultivar improvement by half-sib family selection (Bradshaw et al 2002) and 25% for seed yield in B. rapa spring cultivars (Falk et al 1998).…”