I've done research in the past involving ethylene. While ethylene is involved in the sex determination, I never heard the seed thing. Ethylene can be ordered from your local welding shop, as can propylene gas, which is much less effective.
Of note, in the late 60s there was a scientific publication demonstrating the changing of male to female plants using ethylene. The diecious examples were cannabis and cucurbits. While in black and white, the publication does have pics.
I think you are talking about the following one (I'll paste the abstract)? But again, it's showing that female gynoecious plants can be made to produce flowers (which will then produce pollen) using ethylene gas (the same result can be made using a colloidal silver spray without jumping through the hoops of using a gas like ethylene). But this is completely different from altering the genetic information of a seed. I'm having to assume this is the experiment you are referring too as I've seen it referenced along this topic before - people were also confusing the C. sativus plants used (which is a cucumber) and not C. sativa. I apologize if this is not the one you are thinking of.
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Ethylene: A Natural Regulator of Sex Expression of Cucumis melo L.
(cucumbers/gynoecious/monoecious/perfect flowers/muskmelon)
R. E. BYERS*, L. R. BAKER, H. M. SELL, R. C. HERNER, AND D. R. DILLEY
Departments of Biochemistry and Horticulture, Michigan State University, East Lansing, Mich. 48823
Communicated by Anton Lang, January 11, 1972
ABSTRACT Sex expression in cucumber (Cucumis
sativus L.) and muskmelon (C. melo L.) was correlated
with endogenous ethylene production. Plants of gynoecious
(all female) sex types of the two species produced
more ethylene than monoecius (male-female) plants.
C. melo plants of a gynoecious sex type that normally
produce only pistillate (female) flowers, when grown with
hypobaric ventilation to facilitate removal of endogenous
gases by diffusion, produced perfect (hermaphroditic)
flowers. When either the plant was returned to atmospheric
pressure or when the reduced-pressure ventilating stream
was supplemented with ethylene, the same plants produced
pistillate flowers. Enrichment of the atmosphere
at either normal or reduced pressure with C02, a competitive
inhibitor of ethylene action, also resulted in development
of perfect flowers. Foliar application of a benzothiadiazole,
a postulated inhibitor of ethylene action, resulted
in formation of perfect flowers on gynoecious plants of C.
melo and of staminate (male) flowers on gynoecious C.
sativus. Based on these findings, it is proposed that ethylene
is an endogenous regulator of sex expression in C.
sativus and C. melo.
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