Breeding a new broccoli variety

Jonathan and Jessie Spero
Lupine Knoll Farm Oregon Tilth Certified Organic
1225 Messinger Rd. Grants Pass, Oregon
Mail: P.O. Box 16 Williams OR 97544
email: pogo@mcmatters.net Ph. (541) 846-6845

Breeding a new broccoli variety – breeding for organic conditions - Selection at 0.02%

The goal: to create a vigorous open pollinated broccoli variety, developed to thrive under organic conditions, able to survive weed pressure, and able to produce with less than optimal soil fertility.

The method: This project continues work begun by Oregon State University. In 2002, seed was provided to me from O.S.U. through the Farmer’s Cooperative Genome Project (which operated under Oregon Tilth). This seed from O.S.U. is a diverse population of open pollinated broccoli varieties that had been mixed and grown together. In 2003, I grew out about 150 plants from this breeding stock provided by the University. I selected about 30 plants and saved seed, part of which was returned to O.S.U. I had 10 lbs. of seed from those selected broccoli plants left over, and this was used for this 2009 grow-out..

I planted very densely on a challenging site. This ground has a high weed seed load (mostly pigweed/wild amaranth and veronica). Last year the site was in corn, which left it fairly nutritionally deficient. The 40’ x 200’ site was disked in and roto-tilled once. The seed bed was not thoroughly prepared. 4 beds, each 6 feet wide and 200 feet long, were created. Fertilizer consisted of 100 lbs. of composted chicken manure and 1 yard of raw llama manure on each 6’ x 200’ bed.

On April 1, 2009, I broadcast – sowed 2 pounds of broccoli seed (200,000+ seeds) on each 6’ x 200’ bed. Of these 800,000 broccoli seeds, about 100 plants remain to mature seed after surviving both vigorous natural competition and human selection. (Aug. 9, 2009)

I weeded and thinned. What came up, as you might guess, is a thick carpet of broccoli seedlings and weeds. The method used for weeding and thinning I refer to as “rescue weeding”. It is a useful tool in selecting for vigor. I don’t want the plants to have too easy a time. Only enough weeding is done to keep the best plants barely ahead of the weeds. The plant needs to be able to survive while being crowded by other broccoli and weed seedlings. 2-3 weeks after germination, the healthiest broccoli seedlings were thinned to about a 1” x 1” spacing, then 2 weeks later, plants were further thinned to about a 2” x 2” spacing. Weeding consisted of rescuing the plants from being overwhelmed and giving the most vigorous an extra inch of space. I spent 20 hours per week for three months weeding and thinning. Each bed was visited one per week and weeded at a rate that allowed me to complete weeding the bed in 5 hours. Nothing was ever thoroughly weeded.

This left roughly 5000 plants per bed which were allowed to grow with at least a 2” x 2” spacing. Roughly 1000 remained vigorous enough to make a head. Selection of the heads was for a long neck for easy harvest, a tight bead and a slightly purple tinge to the beads. About 100 plants per bed were kept as seed candidates. The others were removed before they could create pollen.
High temperatures (100°F) during flowering provided an extra challenge and about 1/3 of the plants failed to produce seed. Of the remaining plants, the forming seed heads were evaluated for quality and for a blue-green rather than a yellow-green color on the maturing seed pods.

As of August 9, 2009 the 100 chosen plants are maturing seed.