I've read a few interesting posts about different hybrids and crosses that members have created and I was wondering how they are developed (i.e. the techniques used)? If I wanted to cross two varieties, would I take a cutip and rub one flower and then the other or are there other methods to do this? Does it matter which flower becomes the fruit that the seeds are harvested from?

I'm not an expert here, but I can fill in a few points. Hybridization is more or less limited to varieties that require pollination (you do get some zygotic embryos that survive in polyembryonic varieties, but usually the seeds of all citrus that grow true from seed are going to be clones of the mother plant. However, that relates to the second part of your question--if for instance you wanted to hybridize a Lisbon lemon (polyembryonic), you would have to use the male part of Lisbon lemon (pollen) and cross that with a monoembryonic variety using the female part of that plant by putting the pollen from the lemon on the stamen of the variety that you want to cross.

And when you grow the "hybridized" seeds produced from fruits that you have control over its pollination, let the seeds grow side by side. Those that grow uniformly with the same vigor and leaf patterns are most likely the clones, and you can kill them off, and leave the others which are either stunted or more vigorous than the majority. That way, you can increase your chances of slecting against the clones and having more chances of getting a hybrid.

Skeeter, Close but a little off. The pollen is in the stamen, so you put the pollen on the stigma of the variety that will be the mother plant.

To make it even cleaner or preventing self-pollination, the stamens of the flower of the designated female parent (the one that will contain the hybrid seeds), are emasculated when they are still young, long before they shed. This way, all you have to do is to pluck the flower of the designated male parent when the pollens are shedding, and rub the stamens against the stigma of the female parent flower.

After the stamens are emasculated, the flowers are covered with filter paper bags or some cloth or porous materials to let air in but not the pollens and other insects, to minimize accidental pollination from undesired or unknown sources. And the cover stays there after you hand pollinate the flowers to prevent other pollen contamination.

Thanks for all of the replies. For emasculating the designated female parent, do you simply cut off the stamens once the flower has opened?

It depends upon the cultivar. Some of them could already have pollens shedding before the flowers fully open, especially those that are designed for self-pollination. But most citruses do not shed pollens the moment they are first fully open. I would start emasculating the moment I can get access to the stamens. My wife is a nurse and she has tiny scissors that can get the job done if needed, you can also use the ladies under-arm hair puller, they are narrow enough to cut the stamens easily. But I am not hybridizing, so I haven't done such. But many of my colleagues do, so I have seen it first hand several times. From rice plants, which are harder to emasculate, to orchids, citruses, and bananas.

Is there anywhere that has a list of which citrus are polyembryonic and which are monoembryonic?

Meyer Lemon,Clementine Mandarins, King Mandarin, Pommelo, Temple Mandarin, Minneola Tangelo, Yuzu and Orlando Tangelo are some of the mono embryonic varieties. There probably are others that other members of this forum could add to this list. - Millet (1,361-)