As our long duration pigeon peas here at NARIC set flowers at last, I’m reminded of a conversation I’ve had with a few network members about saving seeds of this crop.
Pigeon peas, Cajanus cajan, are members of the family Fabaceae and have perfect flowers, meaning they can self-pollinate. However, ECHO North America has always adopted an isolation distance of 800m for pigeon pea to prevent cross-pollination, meaning we can only grow one variety on the farm at a time. Given that pigeon peas are one of the most popular items on our catalog and we maintain many varieties, this restriction makes it difficult for us to both maintain sufficient seed stock and trial new varieties.
There is not much published research on isolation distances for many crops, especially ones we would consider “underutilized.” However, a few network members have shared anecdotal experience that smaller isolation distances for pigeon pea - closer to just 200m - are indeed sufficient for variety maintenance. And while pigeon peas have captured our curiosity in this area, this conversation is not unique to them - we wonder this same thing about many other crops such as lima beans, winged beans, scarlet runner beans, eggplants…
Do you have experience with variety maintenance, or even breeding? What observations have you made about rates of cross-pollination between varieties of self-pollinating crops? What resources do you use to plan for proper isolation?