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A Comparison of Russet Burbank Seed Sources
K.A. Rykbost and J. Maxwell'
INTRODUCTION
Seed potato production in North America is in a period of transition. Meristem propagation techniques, flush through systems, postharvest testing for virus diseases and mandatory use of certified seed
are in various stages of adoption in seed growing regions. Private
companies are entering the system as producers of nuclear seed stocks in
growing numbers. Commercial growers are being offered a larger selection of options in 'strains' of a given variety, and in generation or
class of seed. Perceptions as to the quality of various sources or
'strains' are guiding seed acquisition decisions. These may or may not
be accurate.
Meristem propagation techniques allow very rapid multiplication of
large quantities of seed from one or a few tubers. If superior, or
inferior, genotypes are used as the initial source, performance of
commercial crops several generations later may be quite different. The
selection of material to be used as the source for rapid multiplication
may be very important if 'strain' differences can be documented. In the
short term, commercial growers are more concerned with the performance
of available options, including any effects that may be due to storage,
handling or shipping of seed to the commercial grower.
This experiment was conducted to compare several generations of
Russet Burbank seed, derived from several origins.
PROCEDURES
Ten seed lots were planted on May 25 in a randomized complete block
design with four replications. Plots were two rows, 30 feet long. Seed
was spaced at 12 inches in 32-inch rows. Fertilizer included 600 lbs/A
of 16-16-16 banded at planting and 80 lbs N/A applied as solution 32 on
June 5. Vines were desiccated with diquat at 1.0 pint/A on September
21. Potatoes were harvested on October 9 and approximately 120-pound
samples from each plot were graded in early November.
Seed 'strains' included two distinct lines being maintained in the
Oregon Foundation Seed Project (OFSP), the standard OFSP line, a line
from a commercial seed propagation company (COMM) and a Montana strain
from a prominent seed supplier. Seed class ranged from nuclear to
certified. The certified lot was grown in Klamath County for one year.
1/ Superintendent/Associate Professor, Biological Sciences Research
Technician, respectively, Klamath Experiment Station
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RESULTS AND DISCUSSION
Plant emergence was 93 percent or greater 26 days after planting and
98 to 100 percent in all lots 33 days after planting. There were no
visible virus diseases in plants from any of the seed lots. Crop
development was influenced to some extent by adverse soil conditions,
probably related to high salt content. Weed competition late in the
season reduced crop vigor and yields. Early dying was more extensive in
the certified and foundation lots than in early generation seed lots.
Significant differences in yields and tuber size distribution were
observed between seed lots (Table 1). Early generation seed produced
larger tubers and a greater yield of No. l's. The certified lot originating in Montana was inferior to all other lots. Clone 39 in the OFSP
was significantly higher in yield of 10-ounce tubers than seven other
lots and had an attractive tuber type. This clone was also superior to
clone 1 in a 1988 comparison. The foundation lot from Montana produced
the highest total yield but tubers were smaller. While this is desirable for seed production it is detrimental for fresh market or processing crops.
Seed costs may represent up to 30 percent of the costs of production
for potato crops. The differences in price for certified versus foundation or G IV class is generally quite small A small reduction in
yields or size due to virus diseases, blackleg, early dying or other
pathogens that tend to increase with seed generation, can easily offset
seed price advantages for lower class seed. Crop values were calculated
based on fresh market prices described on page 83. Based on a seed rate
of 20 cwt/A and a price differential of $3.00/cwt between classes, it is
very clear that higher class seed paid large dividends in this experiment. At more typical crop prices the use of high class seed would
still be economically advantageous.
SUMMARY AND CONCLUSIONS
Using current seed production technology, sufficient quantities of G
IV seed can be produced to meet the needs of commercial production for
fresh market and processing crops. Seed source studies consistently
show that high quality seed does not cost, but pays.
Differences between 'strains' of Russet Burbank are generally less
readily demonstrated than those between seed classes. In two years of
comparison the OFSP clone-39 has exhibited slightly higher yields of No.
l's than clone-1 and an equivalent generation derived from a commercial
seed propagation company. The current OFSP stock, included as a G II
source in this experiment, performed well in both years.
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If an improved line of Russet Burbank can be identified it would be
very beneficial to the industry to use it as the source for propagation
of basic seed stocks. To date no clear-cut improvement has been
identified. Seed purchasing decisions should be made on the basis of
factors other than perceived or advertized claims of superior 'strains'
of Russet Burbank, keeping in mind that higher classes of seed generally
perform better than the certified class or uncertified seed.
Table 1. Yield and crop value of ten Russet Burbank seed sources, Klamath
Experiment Station, 1989.
Seed
Source
Yield U.S. No. l's
Yield Crop
4-6oz 6-10oz >l0oz Total B's #2's Culls Total value
cwt/A
$/A
Nuclear-COMM
GI-COMM
GII-COMM
GII-OFSP
GI-OFSP-Clone 1
120
133
164
121
114
123
110
129
118
115
73
68
70
87
81
316
311
363
326
310
84
93
88
76
85
51
39
40
46
49
48
63
30
33
30
499
506
521
481
474
3867
3740
4057
3950
3810
GI-OFSP-Clone 39
GIV-OFSP
F - OFSP
F - Montana
C - Montana
107
100
112
161
81
125
101
95
115
95
112
74
46
42
58
344
275
253
318
234
56
90
111
139
51
48
42
32
39
47
44
39
50
30
53
492
446
446
526
385
4325
3471
3080
3586
3010
Average
CV (X)
LSD (.05)
121
32
56
113
24
NS
71
35
36
305
25
111
87
38
48
43
42
NS
42
60
NS
477
20
137
3690