Open-pollinated, on-farm breeding offers important advantages to the farmer/breeder to adapt a crop to his or her unique environment.
Fifth Crow Farm is a certified organic produce farm located near the Pacific coast in central California, a few miles from the picturesque town of Pescadero. The region is both blessed and challenged by the maritime climate. Summer and winter temperatures are moderate, and days are often foggy.
The good folks at Fifth Crow, Teresa Kurtuk, Mike Irving, and John Vars, were gracious enough to allow us to undertake a plant improvement project on their land. Over a delicious farm-fresh lunch, we discussed strategies for integrating the seed work with their on-going vegetable farming activities.
For this location, I chose to work with two OP brassicas; a Napa-type (heading) Chinese cabbage called Nozaki Early, and an heirloom broccoli called Early Green, favored for its high-yielding production of side shoots. In the commercial trade, both of these crops are dominated by F1 hybrid varieties, which means that farmers cannot save their own seed. We feel it is necessary to offer more choices of good quality open-pollinated varieties for seed sovereignty and food security.
My goal from the outset was to develop a vigorous and reliably-heading Napa cabbage, and a broccoli with tight, well-formed heads, and extended harvest. Seedlings were placed in the field in early May. We planted about 750 transplants for each crop.
All selections were made prior to any flowering, to avoid pollination from culls. Chosen plants are flagged, and left to mature. This approach has the added benefit of allowing harvest for fresh produce of any plants not to be saved for seed.
With the Napa cabbage, I was selecting for sturdy, dense, upright heads of substantial size. The ideal form was barrel shaped, however, I allowed for some variation in the size and shape, if a plant showed outstanding vigor.
While the entire field harbored this disease, certain areas were especially hard-hit, as can be seen by the gap in the middle of the plot above. At first this seemed like a disaster, but we quickly realized that, rather, it might be an opportunity to select for club root tolerance in our crops.
The broccoli was also affected by club root, though not as seriously as the Napa cabbage.
The first Napa cabbage plants began flowering in late June, and by late July every remaining plant was flowering.
Each plant was harvested and processed individually. Seed yields per plant ranged from 1-20 grams (2/3 oz) for Napa cabbage and 6-95 grams (over 3 oz) for broccoli.
The threshing step, i.e., removing the seed from its pod and stem, was accomplished by hand-rubbing.
A small, round-holed screen allowed for all the seed (and a little chaff) to drop into the container below.
Not quite clean...yet.
With the cleaning process completed, the seed is put in individual bags. We have now begun year 2 of the project. Last year was the initial field selection. This year we will conduct the progeny testing. For both the Napa and the broccoli, we have planted 30 seeds from each of the 50 highest seed-yielding plants from last year. In a few weeks we will transplant out the most vigorous 15 plants from each of these, for a total population of 750 for each crop. In the coming year, I will evaluate each group of fifteen plants as a distinct "family". This is called progeny testing. As I discover superior families, I will eliminate the less desirable groups. I call this sheparding the good genes. More on this process in a future blog.