Forcing Rhubarb

In 1971, the North Willamette Agricultural Experiment Station obtained several selections from the forcing rhubarb varieties Victoria and German Wine from Washington State University as well as the variety Crimson and several breeding lines from Oregon State University, Corvallis, for a total of 24 lines. All lines were propagated by crown division and five plants of each maintained until 1977. Based on previous observation at WSU and OSU and field observations of vigor and quality at the North Willamette Station, 18 lines were selected in January 1978 for further observation. The lines OSU 12, 21, 22, 23, 34, and 183 were discarded at that time. Three crowns of each of the 18 lines were removed to a hot house for forcing and the remaining two crowns left in the field for propagation.

Methods

All crowns for forcing were dug on January 18, 1978, and washed with high pressure water. The crowns were then moved to a greenhouse bench and held at about 55°F for forcing. The entire forcing area was covered with black plastic drapes to exclude sunlight. Each crown was sprayed with two ounces of 250 parts/million gibberellic acid. Crowns were watered daily and 1 percent Captan was applied during the second week of harvest to control diseases. The crowns were harvested approximately every fifth day starting on February 8, 1978.

Results

The lines GWR1, GWP4, OSU 19, and OSU 216 rapidly proved to be inferior to the other lines and were discarded. The remaining two crowns of the other 14 lines were divided into three starts each and were replanted on February 15. The earliest lines to produce marketable spears were Victoria Bl, Victoria B8, Victoria H 10, Victoria I4, and Victoria A5, each with more than 15 percent of the spears harvested by February 13.

The highest total yields were obtained with Victoria A5, VI4, VH10, VC6, VB1, and VB8 in descending order (Table 1). The lines with the largest mean spear weight were German Wine Sasaki (N3), GWR1, Crimson, GWP4, Victoria H10, and GWP3. Best color was obtained with Crimson, OSU 358, and Victoria B8. Considering the combination of spear size, yield potential, and quality, the best lines were Victoria H10, Victoria B8, Victoria B1, Victoria A5, Victoria C6, and Crimson.

Table 1. Cumulative Rhubarb Forcing Yields - 1978                               Variety or line    Marketable      Rank     Yield     Rank   Color   EarlinessZ                    spears/crown             lb/crown                             Crimson                92           9(tie)   9.0        7    excellent	ML  German Wine P3         72	   12	     6.6       12    poor-fair	ML  "        "  P4         46	   16	     4.2       15    poor-fair	L  "        "  R1         34          17        3.4       16    poor-fair  ML  "        "  T2         92           9(tie)   7.6       10    fair       ME  "        "  Sasaki(N3) 62          14        6.2       13    fair       L    0SU 19                 28	   18	     2.0       18    poor-fair	L  OSU 216                48	   15	     3.0       17    poor-fair	L  "   358                82	   11	     6.8       11    good	ML  Victoria A5           158	    1	    12.2        2    fair	E  "        B1           124           5(tie)  11.0        4    fair       E  "        B8           124           5(tie)  11.2        3    fair-good  E  "        C6           128           4       10.8        5    fair       ME  "        E2           104           7        8.6        8    fair       ME  "        E10           96           8        8.0        9    fair       ME  "        Ell           68          13        5.6       14    poor-fair  ME  "        H10          136           3       12.6        1    fair       E  "        I4           150           2       10.6        6    poor-fair  E       ZE, early; ME, mid-early; ML, mid-late; L, late.  

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