Cross pollination affects next years gourds: Create your own designer gourds of different varieties grown in the same area without disciplined hand pollination will cross pollinate. Cross pollination will not alter the size or shape of the gourd you have planted. In other words, if you plant a Sennari, and the female Sennari receives pollen from an African Zulu, the Sennari that grows on the vine will not be altered in size and shape, however, the seeds inside the Sennari will grow a new shaped gourd, and possibly a variety of shapes. Leaving this process to the random acts of nature, a variety of gourds would produce seeds that would grow an undefinable variety of shapes and sizes. What do you do if you want something specific?
There is no set of rules that will allow you to create the perfect gourd of your desires, however there are some rules of thumb that you can use to apply so you can direct your cross pollination with a goal in mind. Rather than shaping and sizing your next years gourds, you can influence the size and shape of next years gourds.
SHAPE: While the male plant will not absolutely replicate itself through the seeds of the female, however the male plant will bear a very strong influence on the shape of the next generation gourd. The female will also have some influence on the shape, so if there is a particular size and shape you are trying to accomplish, you should select your female with this in mind and pick a female gourd that is similar, or at least not totally opposing the desired shape you are trying to achieve. We did successfully create a kettle gourd about 1 pound in size by cross pollinating a male kettle with a mid sized Sennari. We also got an African Zulu gourd to have a pointed crown cao by cross pollinating a male Hyakunari flower with a female African Zulu.
SIZE: The female to be pollinated will have its strongest influence on the size of the gourds that will be grown in the next generation. The easiest way to think of this, and remember which one influences size, and which influences shape is to look at the female. If you are talking a small female like a Sennari, the gourd is small, and therefore the seeds are small. Small seeds will grow small gourds, large seeds will grow large gourds, therefore, the female will have it’s greatest influence on the size of your new designer gourd and the male will have it’s influence on the shape
We do not have the time nor the area at this point to attempt this, but if someone is interested we would love to see the outcome of the following cross pollination, this is a designer gourd I'd like to see:
If you are pushing for a specific shape like a very large bottle gourd, it may take a few years and a carefully controlled pollination process. If you want a huge Mexican Bottle, you may want to hand pollinate a male mexican bottle gourd flower with a female 50 pound kettle. Protect the pollination process, (see our hand pollination tutorial) and next year grow Mexican bottle gourds again, as you may need to cross pollinate with the male again to further influence the desired shape.
Once you have the desired shape gourds, protect those seeds, and hand pollinate them generation after generation. During this process simply use selective breeding, and pick the gourds that are closest to your desired final gourd. I have been told that once you have isolated a variety of gourd for 5-7 generations you then have a new successful variety.