Robertson (Old Budline) (sec. NPGS/GRIN 2010)
Citrus x aurantium L., pro sp. [Sweet Orange Group] (sensu Mabberley 1997, Bayer et al. 2009); Citrus sinensis (L.) Osbeck (sensu Swingle and Reece 1967; sensu Tanaka sec. Cottin 2002)
Hodgson (1967) noted that:
"Robertson originated as a limb sport in an old Washington navel tree in an orchard near Redlands, California, where it was found by Roy Robertson in 1925. It was patented (U.S. Plant Patent No. 126) by Armstrong Nurseries of Ontario, California, and introducer to the trade in 1936. Although planted and topworked to some extent, it has not become commercially important in California or Arizona, nor apparently elsewhere. However, because of its small tree size and early and high productivity, it is popular as a dooryard or container-grown patio tree."
Crown compact or dense, not weeping. First-year twig surface glabrous; second- or third-year twig surface striate; thorns absent or not persistent; prickles absent or not persistent. Petiole glabrous, length short; wings narrow, adjoining the blade. Leaflets one, margin entire or bluntly toothed, shade leaflet blades flat or weakly conduplicate, sun leaflet blades weakly or strongly conduplicate. Scent of crushed leaflets sweetly orange-like. Fruit as broad as long or longer than broad; rind yellow (7-10), yellow-orange (11), orange (12), or red-orange (13); rind texture slightly rough (4-5) or medium rough (6-7); firmness leathery; navel present; flesh orange; taste acidic-sweet.
Hodgson (1967) provided the following additional notes on the cultivar:
"Fruit virtually indistinguishable from Washington except for medium-large size, slightly lower quality, and earlier maturity, which is usually ten days to two weeks. While maturing about the same time as Thomson, quality is better and fruit is retained much longer on tree. Because fruit is often borne in tight clusters, its shape is sometimes slightly distorted and exhibits flat contact surfaces.
Tree lacking in vigor (more so than Thomson), small (markedly dwarfed on sour orange rootstock), heat-resistant, precocious, and very prolific.
The heat resistance and associated high-yielding behavior of the Robertson navel orange appear to relate to the fact that, although it blossoms at about the same time as other varieties the young fruits develop more rapidly and pass through the fruit-setting phase earlier. The fruits thus escape the severe dropping associated with the heat and dryness normally characteristic of the later fruit-setting period of other varieties (Coit and Hodgson, 1919)."
Bayer, R.J., D.J. Mabberley, C. Morton, C.H. Miller, I.K. Sharma, B.E. Pfeil, S. Rich, R. Hitchcock, and S. Sykes. 2009. A molecular phylogeny of the orange subfamily (Rutaceae: Aurantioideae) using nine cpDNA sequences. American Journal of Botany 96: 668–685.
Coit, J.E. and R.W. Hodgson. 1919. An investigation of the abnormal shedding of young fruits of the Washington navel orange. University of California Publications in Agricultural Science 3: 283–268.
Cottin, R. 2002. Citrus of the World: A citrus directory. Version 2.0. France: SRA INRA-CIRAD.
Hodgson, R.W. 1967. Horticultural varieties of Citrus. In: Reuther, W., H.J. Webber, and L.D. Batchelor (eds.). The Citrus industry, rev. University of California Press. http://lib.ucr.edu/agnic/webber/Vol1/Chapter4.html.
Mabberley, D.J. 1997. A classification for edible Citrus (Rutaceae). Telopea 7: 167–172.
Swingle, W.T. and P.C. Reece. 1967. The botany of Citrus and its wild relatives. In: Reuther, W., H.J. Webber, and L.D. Batchelor (eds.). The Citrus industry. Ed. 2. Vol. I. University of California, Riverside. http://lib.ucr.edu/agnic/webber/Vol1/Chapter3.html.
Search for this cultivar in NCBI Entrez
Additional information on this cultivar at University of California: Riverside Citrus Variety Collection
Citrus ID Edition 2
October, 2011
idtools.org
