Plant breeding for organic and sustainable, low-input agriculture

Evidence on genetic variability among and within three runner beans local landraces (P.
coccineus) grown under organic farming conditions
Vasilios-Chatzitheodorou 1 , Athanassios-Mavromatis 1 , Athanassios-Korkovelos 1 , Ebrahim-
Khah 1 , Christos-Goulas 2
1 Laboratory of Plant Breeding and Genetics, University of Thessaly, Volos, Greece;
2 Laboratory of Vegetable Production, Aristotle University of Thessaloniki, Thessaloniki, Greece
Runner bean (Phaseolus coccineus) is mainly a cross pollinated species but seems to have high
percentage of selfing and is one of the most popular grain legumes in Mediterranean countries.
Although commercial cultivars are currently available, the majority of growers are cropping
local landraces either for self consumption or for production in both conventional and organic
farming use.
In this study farmer’s seed from three distinct areas different in their altitude were used.
Landraces were: Distrato, Zagora and Prespes grown in high, medium high and medium altitude
respectively. The three landraces entered field evaluation during 2004-05 growing seasons in the
University of Thessaly Experimental Farm in Velestino-Volos under organic farming conditions
in a nearly sea level growing environment. Sixty individual fully competitive plants were
evaluated from each landrace in a grid mass selection arrangement. Planting was in hills at a
final density of one plant per m 2 . Dry bean yield on a per plant basis along with number of pods
and 100 seed weight was recorded.
Selection for high dry bean yield was practiced. Selection intensity was 0.10 (one plant from
each grid) and the six half sib families (HS) selected were pooled to form C1 HY composites for
each landrace. Bidirectional selection (high vs low) for dry bean yield was practiced within each
of the three C1 HY composites following evaluation during 2005 season in the same manner as in
2004. Seed from the six high yielding plants and the respective low yielding ones were pooled to
form the respective high and low composites (C2 HY vs C2 LY) from each landrace. The resulted
six composites were further evaluated during 2005 season following the procedure previously
described. Furthermore five plants from Co were selfed to create S1 families (2004) and next
year 2005 formed the S2. According to agronomy performance, high significant differences were
found in yield, number and weight of pods per plant. Data indicated that Distrato and Prespes
landrace were of the same yielding potential and superior as compared to Zagora. Bidirectional
selection was effective in the organic environment giving a mean response 15% per year.
Furthermore, the heterogeneity of landraces was expressed better (in organic environment) as
was proved from the initial population of Grevena (C0) originated from highlands and expressed
the highest genetic variability among all landraces. This growing season a simultaneous
evaluation for C0, C1, C2 and S1, S2 families for each landrace was applied to estimate the
inbreeding effect, the real genetic gain and the efficiency of the selection method.
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