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I hear a lot of reports from fellow gardeners about spontaneous crosses showing up within various inbreeding crop species. Many common crops, such as tomatoes, peas, and beans typically self pollinate, and when different varieties are grown adjacent to each other, there is often no crossing between them...but sometimes there is. If your goal is to maintain a stable variety, you may find inbreeding crops particularly easy to work with, but if you are a plant breeder looking for diversity, spontaneous crosses can be very exciting.
Well, I wanted to breed plants and discover new diversity, but none of the self pollinating plants I was growing seemed to be interested in doing any out-breeding. Then, finally, my peppers gave me the gift of a surprise F1 hybrid. I was thrilled at the opportunity to finally do some breeding with a typically inbreeding species.
Pasilla Bajio x Hungarian Yellow Wax F1
For several years, I have been growing a mix of medium heat pepper varieties in a dense block planting and saving the seeds hoping for some crosses. After just a couple of seasons, I noticed the first F1 hybrid phenotypes show up. Interestingly, it seems that some varieties show a greater tendency to cross through natural methods. This is probably due to differences in the flower structure, and could certainly vary depending on the insects present in a particular garden. The first crosses I discovered showed up in Pasilla Bajio plants descended from seeds I purchased from Botanical Interests. I'm not sure if this variety always has a higher rate of out crossing, or just the particular strain that is sold by this company. Oftentimes, the majority large seed companies purchase their seeds from the same wholesale seed grower, so there is a high likelihood that this variety will tend to cross wherever you purchase it.
In 2017, the year I found the crosses, I planted my Pasilla Bajio plants in a block with several of my other favorite varieties -- just like always -- and I kept the plants labeled. I only grew 3 plants of this variety, and all of them turned out to be crossed. Two of them had immature fruits that were yellow and pointed upward, so I assume they were crossed with Hungarian Yellow Wax. The other one looked like it had crossed with Mulato Isleno. These crosses occurred in 2016. In 2018 I grew out a small amount of the F2 seeds that I had collected from the crossed plants the previous year. To be honest, those F2 plants weren't particularly thrilling, but they weren't bad either. Many of the plants were leggy, or only moderately productive, but they were all good for throwing in a pot of beans or a stir fry. Some were also fairly thin-fleshed pods that were good for drying.
The cross I am more excited about was between Hungarian Black and Hungarian Yellow Wax. These were two of my favorite peppers to begin with. They both have unique flavors; HB is somewhat smokey; HY is kind of fruity. They also both have visually unique phenotypes. These peppers probably crossed in my garden in 2016. I sent seed from Hungarian black to a friend in the upper midwest, who discovered the F1 cross with Hungarian Yellow in 2017 and sent the F2 seeds back to me. I grew the F2 plants in 2018. The photos below show the diversity that came out of just a small number of F2 plants.
My plan with this cross is to select for some anthocyanin pigmentation and yellow immature pods. I don't necessarily need to stabilize this combination. I would be happy with a diverse genepool where combinations of these traits show up reliably. I am also interested in a chile pepper landrace mix which contains many segregating hybrids of peppers with a similar heat level. The descendants of both of these crosses (as well as others) have contributed to this landrace. I have seeds for sale of both of these breeding populations.
In the process of researching pepper breeding, I have found a few other useful tidbits of info in scientific literature.
Odland and Porter reported 7.6 to 36.8% crossing in the field with a mean of 16.5%. Cultivars differ significantly in the amount of crossing, due to different flower structure (such as proximity of anthers to stigma) and kind and number of insect in the field.
Small oblate fruit crossed to large elongate yields F2 segregates of: 3 oblate : 1 elongate. The F1 is intermediate in size and shape and the F2 displays a continuous range of size and shape. These phenotypes are controlled by polygenes, with small being dominant. Because about 30 genes control fruit size, large fruits cannot be recovered in the F2. Four or more back-crosses are required to recover the fruit size of the larger parent. (Khambanonda 1950)
Hot fruits are dominant over non-hot. In crosses between hot and sweet varieties this trait segregated for 74-83% hot plants in the F2. (Deshpane 1935) (Webber 1912)
So, don't be dismayed if you find off-type fruits showing up in your in your pepper patch. It may be a good opportunity to embark on a new breeding project.
I am also selling seeds of my breeding populations derived from both accidental and intentional crosses