Cucurbit Genetics Cooperative Report 3:22-23 (article 12) 1980
Effectiveness of AVG for Inducing Staminate Flowers on
Gynoecious Cucumbers
A.P.M. den Nijs
Institute for Horticultural Plant
Breeding, Wageningen, The Netherlands
The amino-ethoxy of rhizobitoxine, amino-ethoxy-vinyl-glycine
(AVG), inhibited ethylene production in muskmelon seedlings
and improved fruit set following hand-pollination of emasculated
muskmelon flowers (1).
Staminate flowering in gynoecious cucumbers can be induced
by gibberellins, silver nitrate (AgNO3)
and silver thiosulphate (Ag(S3O3)33-),
which interfere with ethylene-production. Because of the
promising results of AVG-treatment obtained by Tolla (personal
communication), I compared its effectiveness for induction
of staminate flowers with that of standard treatments of
other silver compounds.
In a glasshouse trial six potted plants each of gynoecious
hybrid slicing cultivars Farbio and Sandra and of gynoecious
inbred pickling line were treated at the first true leaf
stage with three concentrations of AVG along with AgNO3 and Ag(S3O3)33-.
Seeding was on June 15 and treatment two weeks later. All
solutions were prepared with distilled water and sprayed
with an atomizer. Plants were transplanted two weeks after
treatment and trained vertically without pruning. Temperature
was set at 20°C night/23°C day, but it sometimes
rose to 30°C on bright days. About two months after owing,
each node of every plant was scored for sex expression (Table
1). Only mean numbers of staminate flowering nodes of the
main stem are given because this correlates rather well
with the total amount of staminate flowers produced (2,
3).
The silver treatments gave a similar number of staminate
flowering nodes. The 1,000 ppm AVG treatment gave a slightly
lower level of staminate induction than the silver compounds,
whereas the other two treatments resulted in relatively
fewer staminate flowers. The phytotoxicity of AVG is, however,
very severe at the effective concentration. The first three
to four leaves became extremely chlorotic and necrotic,
and growth was checked for about three weeks. Although the
plants eventually recovered, they remained unthrifty. The
100 ppm AVG application did only slight damage while the
silver treatments gave no noticeable side effects. The AgNO3-treated
plants of Farbio were not scored for reasons other than
phytotoxic effects. The extent of staminate flowering on
side shoots followed the same pattern as that on the main
stem, with most staminate flowers occurring on the pickle
line.
I conclude that under our conditions AVG should not be
preferred over treatments with the standard silver compounds.
The fact that staminate flowers did occur lends support
to the notion that blocking ethylene production/action is
important in staminate induction. I also should like to
mention that, in contrast with an earlier report (2), both
silver compounds were about equally effective in this and
other experiments (3).
Table 1. Mean number of staminate
nodes following treatment of three gynoecious cucumber genotypes
with various chemical compounds.z
|
|
Genotype |
Compound |
Treatment rate |
F1-Sandra |
F1-Farbio |
Gynoecious pickle inbred |
AVG |
10 ppm |
5.0 |
3.0 |
4.7 |
|
100 ppm |
5.8 |
5.3 |
6.0 |
|
1000 ppm |
14.0 |
15.0 |
14.0 |
AgNO3 |
500 ppm, 3 mM Ag+ |
17.0 |
--- |
19.0 |
Ag(S3O3)33- |
3 mM Ag+ |
17.0 |
17.0 |
19.0 |
z No other statistical analyses performed.
Literature Cited
- Natti, T.A. and J.B. Loy. 1978. Role of wound ethylene
in fruit set of hand-pollinated muskmelons. J. Amer.
Soc. Hort. Sci. 103:834-836.
- Nijs, A.P.M. den and D.L. Visser. 1979. Silver compounds
inducing male flowers in gynoecious cucumbers. Cucurbit
Genetics Coop. Rpt. 2:14-15.
- Nijs, A.P.M. den and D.L. Visser. 1980. Induction
of male flowering in gynoecious cucumbers (Cucumis
sativus L.) by silver ions. Euphytica 29
(accepted).
