What determines ratio of female to male flowers on fruiting plants?

I'm talking greenhouse plants such as peppers, cucumbers, courgettes, melons. All of mine have a preponderance of male flowers, probably in the order of 10:1. There possibly is no answer, but just curious as to what factors if any play a part.

 

Peppers are related to tomatoes and don't have separate male and female flowers. With the cucurbits it seems to be temperature plays a big role. In cooler weather they produce male flowers and warmer leads to more female flowers. Just last week my cucumbers had virtually no female flowers in sight and I was pinching off male flowers every evening. This week I have more female than male flowers and it's the same with melons as the season warms up more female flowers. There is also a factor from the number of fruit developing; my cucumbers when they have three or four cucumbers developing on a plant start to produce male flowers if I pick cucumbers females start to appear. Doesn't apply to modern all female cucumbers and no they don't count as such, it's probably due to the stress imposed by the developing fruit. This is also the case with squashes outside.

 

I'm not sure there is any thing you can put your finger on that creates Male or female flowers.
As @NigelJ has said most plants don't produce Male and female flowers, but regarding vegetables the curcurbits are probably the most important.
Male flowers are almost always produced first, but I find with melons you have to pinch out the growing points and female flowers come on the sub laterals

 

Nigel's point about temperature affecting the production of fruiting flowers seems logical given this summer's on-off weather, also it is reasonable to assume that the energy going into the production of actual fruit may inhibit the appearance of further females until harvested. I take Pete's point about nipping out the growing tips of melons, which have been my most successful crop this year. (As an aside, I've taken to hand-pollinating all of my stuff bar tomatoes and courgettes following an abysmal season last year.) Thanks for your inputs.

 

I find peppers and tomatoes pollinate without my deliberate help, courgettes, squashes and melons I have pollinated at various times if they haven't got the idea. Cucumbers, in the greenhouse don't want pollinating so the males get the snip.

 

I think with peppers and tomatoes often the flower, having male and female parts, self pollinates so they come pretty true to type from seed.

 

@TheWingco My cucumbers now have a number of fruits on them and have reverted to producing male flowers as the fruit develop. Once I harvest a few if the weather is still good I will get more female flowers appearing.

 

Complete mismatch of male/female courgette flowers this year, I've been sharing male flowers with a neighbour, without which loads of female courgettes wouldn't have been pollinated.