PNL Volume 16 1984
Gottschalk, W. Institute of Genetics, University of Bonn
Federal Republic of Germany
Eight pea genotypes, homozygous for genes efr for earliness, bif-1
for dichotomous stem bifurcation and for some other mutant genes, were
grown together with the late flowering mother variety 'Dippes Gelbe
Viktoria ' (DGV) under three different temperatures in the phytotron as
- 12.5°C constant
- 12.5°C night, 25.5°C day
- 25.5°C constant
Other environmental factors were identical in the three trials.
The plants were grown under long-day conditions with 18 hr light and
6 hr darkness; humidity was about 60%. The dots given in Fig. 1 repre-
sent the mean values of the trait "number of days from sowing to
beginning of flowering", based on 8 normally developed plants of each
genotype. Genes efr and bif-1 derive from recombinant R 46C. R 46C was
crossed with other genotypes of our collection and the following recom-
binants were used for the experiments:
- R 20D: efr, bif-1 with full penetrance, "long III", reduced
chlorophyll content
- R 20E: efr, bif-1 with full penetrance, "short II"
- R 427: efr, bif-1 with low penetrance, dim for reduced size of
all plant organs, "short I"
- R 831: possibly identical with R 427
- R 836: efr, bif-1 with extremely low penetrance, "wax 445" for
waxlessness, "short I"
- R 837: efr, bif-1 with reduced penetrance, "wax 423" for
waxlessness, "short I"
- R 879: efr, bif-1 with reduced penetrance, "short I"
As expected, most of the genotypes tested flowered earlier under
high temperature than low. This is exemplified by the first 6 recora-
binants shown in Fig. 1. At 12°C they flowered a month later than at
25°C. In DGV the delay was somewhat more. The difference in time to
flower between the plants grown under constant 25°C and those grown
under 12°C night/25°C day was small, demonstrating that the low night
temperature had a minimal effect on flowering time.
Plants of recombinants R 20D and R 20E showed a specific behavior
in that they formed tiny flower buds at very low nodes as does R 46C,
the donor of gene efr. Fully developed flowers, however, were produced
considerably later on higher nodes. In R 20D, grown under constant
25°C, they appeared more than 7 weeks after sowing, and in R 20C more
than 10 weeks after sowing. In both cases, only some of the plants
flowered at all, whereas the others did not produce fully developed
flowers until the trial was stopped. Therefore, the values for these
two genotypes, given in Fig. 1, are not true mean values. Under con-
stant low temperature of 12°C, plants of R 20D required more than 13
weeks to reach flowering, and those of R 20E more than 16 weeks. Some
plants of R 20E did not flower at all. Under alternating high and low
12 PNL Volume 16 1984
temperatures (i e. under approximately normal conditions), however
these two recombinants flowered earlier than at constant 25°C.