Abstract:
Gynoecious inbred lines of cucumbers (Cucumis sativus
L.) with high (HF), medium (MF) and low (LF) percentage of
gynoecious plants were used in crosses with monoecious
Chinese cultivars with high (HN), medium (MN) and low (LN)
percentage of nodes with female flowers. F₁ and F₂ progenies
from these parents crossed in all combinations were studied
to determine the effect of levels of female flowering
expression of gynoecious and monoecious parents on the
percent gynoecious plants. The effect of mating systems on
percent gynoecious plants and percent gynoecious plants with
Chinese cucumber characters, wart-spine and long fruit, was
studied in F₃ families from crosses of HF, MF, and LF
gynoecious lines with an HN monoecious parent. The effect of
planting date on percent gynoecious plants recovered was
studied in the F₂ progenies of an HF gynoecious line crossed
with Taishan, an MN monoecious cultivar. Level of female
flowering tendency, expressed by percentage of female
flowering nodes, in the monoecious parents had a much
greater effect on the percentage of gynoecious plants in the
F₁ and F₂ generation than did the degree of female flowering
in the gynoecious parents. The effect of the gynoecious
parent and the interaction of gynoecious X monoecious parent
on percent gynoecious plants in the F₁ were non significant.
In the mating system study, self pollination of selected
completely gynoecious plants, requiring male flowering
induction by chemical treatment, was significantly more
effective in obtaining highly gynoecious progeny lines than
selfing predominately gynoecious plants or sib-mating
predominately gynoecious and completely gynoecious plants.
There was no interaction between mating system and level of
female flowering in the gynoecious parents.
Planting date did not affect the percent of plants
producing male flowers during the entire growing period, but
early planting produced fewer plants with male flowers
during the first half of their respective growing period
than late plantings. By the end of the season, early and
late planting were about equal in percentage of gynoecious
plants, because a higher percentage of plants in the early
plantings reverted from gynoecious to monoecious flowering
during the last half of the growth period.
