Euphytica 127: 1–9, 2002.
© 2002 Kluwer Academic Publishers. Printed in the Netherlands.
1
Early generation selection for potato tuber quality in progenies of late
blight resistant parents
Dilson A. Bisognin
1,2
& David S. Douches
1,∗
1
Department of Crop and Soil Sciences, Michigan State University, East Lansing, MI 48824, U.S.A.;
2
Sponsored
by Ministry for Science and Technology – CNPq, Brazil; Permanent Address: Department of Fitotecnia, Fed-
eral University of Santa Maria, Santa Maria, RS, 97119-900, Brazil; (
∗
author for correspondence; E-mail:
douchesd@msu.edu)
Received 2 August 2000; accepted 19 November 2001
Key words: chip-processing, early generation selection, Phytophthora infestans, potato breeding, Solanum
tuberosum, specific gravity, tuber appearance
Summary
Developing disease resistant cultivars is one of the major objectives for a potato (Solanum tuberosum L.) breeding
program, but many resistant clones have not achieved commercial acceptance because of late maturity and non-
marketable tuber characteristics. Selection for tuber quality should have greater emphasis in breeding disease
resistant cultivars. The objectives of this study were 1) to evaluate the ability of late blight (Phytophthora infestans
(Mont.) de Bary) resistant parents to transmit chip-processing (tuber appearance, specific gravity, and chip-color)
or tablestock (tuber appearance) quality to the offspring and 2) to compare selecting for tuber quality in single-hill
versus eight-hill generations. We made crosses among eight unadapted potato cultivars (B0718-3, Bertita, Bzura,
Greta, Libertas, Stobrawa, Tollocan, and Zarevo) with reported late blight resistance with adapted susceptible
cultivars/breeding clones to generate 95 populations (4,750 seedlings). Approximately 10% of the progeny from
each cross were selected from single-hill plots based on tuber appearance, number, shape, and internal defects.
These selected clones (408) were evaluated for tuber appearance, specific gravity, and chip-color. The same
evaluations in the following year were made on tuber samples from eight-hill plots. Libertas and Tollocan were
the best parents for transmitting chip-color; B0718-3, Zarevo, and Tollocan for transmitting tuber appearance; and
Bzura, Libertas, and Zarevo for transmitting high specific gravity to the highest percentage of the offspring. Overall,
50% and 56% of the clones based on single- and eight-hill generation, respectively, were considered to possess
chip-processing quality; over 90% of the clones had acceptable tablestock quality. A total of 71% of the clones
possessing acceptable chip-processing and 95% of the clones possessing acceptable tablestock quality selected in
both generations were identified in single-hill plots. The evaluation of tuber quality characteristics in single-hill
generation not only permitted the identification of clones with acceptable chip-processing and tablestock, but also
increased the amount of clonal information for the following generation of selection. In crosses between late blight
resistant and susceptible clones, selection for tuber quality traits can be initiated in single-hill generation using a
moderate selection intensity and precede late blight testing.
Introduction
Breeding for disease resistance is a common objective
for many crop species. Overemphasis on improving
disease resistance can limit yield and other import-
ant traits because of genetic bottlenecks (Kelly et al.,
1998). In potato (Solanum tuberosum L.), late blight
(Phytophthora infestans (Mont.) de Bary) is the most
devastating disease worldwide (Fry & Goodwin, 1997;
Kamoun et al., 1999) and genetic host plant resistance
is one of the major objectives for breeding (Colon et
al., 1995).
Although breeding for late blight resistance has
had greater priority in the last century than for any