THE REACTION OF PISUM GENOTYPES TO EXTREME SHORT DAY CONDITIONS

PNL Volume 18

1986

RESEARCH REPORTS

Gottschalk, W.

Institute of Genetics, University of Bonn

Federal Republic of Germany

Three mutants and 29 recombinants of our Pisum collection were grown

together with their mother variety 'Dippes Gelbe Viktoria' (DGV) in the

phytotron under extreme short day (SD) conditions with only 6h light per

day. All the other environmental conditions were the same as in our former

trials (2 5C day, 1 5C night; 60% humidity). Ten plants of each genotype

were grown in Mitscherlich pots. Flowering behavior, plant height, number

and length of internodes were evaluated. The material may be subdivided

into two groups. All the genotypes of the first group are homozygous for

efr, a gene for earliness derived from recombinant R 46C. In addition, the

recombinants of this group contain one or several other mutant genes. The

second group of genotypes do not contain gene efr.

Only three of 20 plants of DGV reached the flowering stage; all others

died earlier in development. A similar behavior was observed for two

mutants and five recombinants, four of them containing gene ef r for

earliness. All these genotypes showed abnormal development under the

unfavorable light conditions. In another group of six recombinants, flower

buds appeared but did not develop further. Four recombinants of this group

are homozygous for efr. The fasciated mutant 489C and recombinant R 142F

were still in a purely vegetative stage when the trial was terminated 83

days after sowing.

The flowering behavior of the other recombinants tested is shown in

Fig. 1. Out of ten plants of R 46C, the donor of gene efr for earliness,

only a single plant formed some fully developed flowers whereas the others

had undeveloped flower buds or they died in earlier stages. Thus, this

recombinant showed the same negative reaction to the low amounts of light

as its mother variety DGV. A completely different behavior was observed

for the recombinants R 840, R 42 7, and R 430, likewise homozygous for efr.

Their development was relatively normal and they produced small amounts of

seed, thus demonstrating a high degree of tolerance to the unfavorable

light conditions.

The table below shows the comparison of the flowering behavior of

these genotypes under normal and under extreme SD conditions.

PNL Volume 18 1986 RESEARCH REPORTS

As expected, a considerably longer time was required to reach the flowering

stage in extreme SI) as compared to normal SD. The difference was espe

cially great in R 430. The significant point, however, is that the;

recombinants were at all able to survive and to produce seeds under these

unfavorable conditions.

The results show that the selection value of specific genotypes, in

our case the cultivar 'Dippes Gelbe Viktoria' and the early flowering

recombinant R 46C, can be considerably improved under the influence of

distinct mutant genes even under extremely unfavorable environmental

conditions.

Fig. 1. The flowering behavior of 17 Pisum recombinants under extreme

short day conditions in the phytotron. The genotypes of the

first group contain gene efr for earliness derived from R 46C.

The genotypes of the second group do hot contain this gene.

DGV ('Dippes Gelbe Viktoria') is the mother variety of our

radiation genetic experiments. Each dot gives the value for

one plant.