Rutabaga × Turnip (Brassica napus × B. rapa)

[Klaus Brugger]

These are F₁ hybrids between rutabagas/swedes (Brassica napus) and turnips (B. rapa). I used yellow-fleshed rutabagas ('Brora' and 'Invitation') as the maternal parents and high-anthocyanin turnips from my breeding population as the pollen donors. The resulting hybrids have either yellow or white flesh and oftentimes some anthocyanin inside – something I haven't seen in pure rutabagas. The flavour is sweet and pleasant and more similar to rutabagas than turnips, but with a less dense texture than rutabagas.







Brassica napus as a species originated from a spontaneous hybridization between B. rapa and B. oleracea. Crosses between B. rapa and B. napus are said to be quite easily achievable, particularly when the amphidiploid B. napus is used as the mother.
 
Tim Peters reportedly combined the two species in his wonderful leafy green populations 'Bear Necessities' and 'Gulag Stars', Vermont's beloved 'Gilfeather Turnip' is said to have both rutabaga and turnip genetics, and in 1917, Kajanus [1] published an extremely detailed report on his experiments hybridizing rutabagas and turnips and growing out the offspring. Rutabaga 'Invitation' itself has a turnip in its pedigree [2].
 
I was still surprised last spring by how successful the bud pollinations with turnip pollen on the rutabagas were – success rates like rapa × rapa crosses. The seeds then germinated well, the plants grew vigorously and fast, leaves looking more like rutabaga than turnip.
 
One thing apparently common to the roots of rutabaga-turnip hybrids is the formation of gall-like structures. Even proliferations carrying adventitious shoot buds have been reported [1, 3]. I did observe some gall-like structures, but not as extreme as the ones pictured in [1]. It's probably advisable to use a turnip cultivar that produces hypocotyl tubers with a thin taproot rather than one where the root makes up a large part of the crop when doing such hybridizations. Kajanus [1] speculated that the galls may be the result of an increased susceptibility to Agrobacterium. That wouldn't be great, of course, and definitely something you'd have to work against.



Sources:

[1] Kajanus, B. (1917). Über Bastardisierungen zwischen Brassica Napus L. und Brassica Rapa L. Zeitschrift Für Pflanzenzüchtung, 4(3), 265–322. https://www.biodiversitylibrary.org/page/4225403

[2] Bradshaw, J. E., Gemmell, D. J., & Wilson, R. N. (1997). Transfer of resistance to clubroot (Plasmodiophora brassicae) to swedes (Brassica napus L. var. napobrassica Peterm) from B. rapa. Annals of Applied Biology, 130(2), 337–348. https://doi.org/10.1111/j.1744-7348.1997.tb06837.x

[3] Beijerinck, M. W. (1886). Beobachtungen und Betrachtungen über Wurzelknospen und Nebenwurzeln. Johannes Müller.

[A. Pel]

Good work, very cool.

Please do post more results as you get them.