Growing Magazine - November, 2008

COLUMNS

Seed Research: New Broccoli Varieties Show Versatility

By Dorothy Noble

Increasingly more popular, partially due to its health attributes, broccoli ranks among the top five vegetable crops produced in the United States in terms of both acreage and value. California produces about 90 percent, much of it in the coastal region.

Breeders strive for high domes on elongated stems, which facilitate both mechanical and manual harvesting. Ideal heads are tight and dome-shaped. Segmented heads appeal to the bunching market, and small beads please processors. Dark green or blue-green color appears healthier to consumers. Both processors and fresh market produce dealers prefer mild, fairly sweet flavor. Of course, growers favor disease resistance, particularly to downy mildew.

Broccoli generally grows best with moderate day temperatures and cool nights. Consequently, much of the production occurs in spring and fall. Several current breeding programs promise more versatility.

Oregon State’s vegetable breeding program, led by Professor Jim Myers, focuses on breeding for disease and insect resistance and for improving nutritional quality. In broccoli hybrids, his work includes developing exserted heads for easier harvest and enhanced nutritive value. His selection efforts in organic systems have been reducing the variability in open-pollinated varieties. In addition, his trials have shown increasing insect resistance and high-temperature tolerance.

The researchers at the Agricultural Research Service (ARS) at the U.S. Department of Agriculture have noticed that broccoli varieties differ in their potential anti-carcinogenic activity.

Dr. Mark Farnham of the ARS U.S. Vegetable Laboratory (USVL) in Charleston, S.C., and colleagues at Johns Hopkins University in Baltimore, Md., have found that concentrations in broccoli of glucoraphanin—a compound associated with the vegetable’s cancer-inhibiting abilities—is influenced more by genetics than by environment.

Farnham reports that it is possible to classify the anti-cancer potential of different varieties according to how their glucoraphanin spurs detoxifying enzyme activity in mammalian cells. USVL has produced higher-glucoraphanin broccoli.

The USVL breeding program has also been selecting the breeding lines for adaptation to summer conditions in the Southeast—hot days and hot nights. This contrasts with many western broccoli lines, which perform well under hot days and cool nights.

R & D Ag, Inc. in Gilroy, Calif., received a patent for a new heat-tolerant broccoli. In September, Syngenta finalized an agreement with R & D Ag to support the development of heat-tolerant broccoli varieties.

Syngenta indicated that these new varieties should allow the expansion of broccoli acreage, increasing options for growers. Syngenta anticipates the first sales of these new heat-tolerant varieties in May 2011.

The following new and relatively new varieties were made available to us by press time. Broccolini, broccoflower, broccoli raab and seeds developed for sprouting will appear in a later issue.

Bejo Seeds’ Batavia demonstrates good performance in cold weather for very early spring production and late fall. Maturing in 70 days, its dome-shaped heads with medium beads are ideal for the crown-cut market.

Late-maturing at 90 days and very uniform, Beaumont features dome-shaped heads on thin stems. This Bejo Seeds variety is good for the bunching market.

Early-maturing Castle Dome (PS 1536) has excellent holding ability. This versatile hybrid offers heat tolerance as well as cold vigor. The compact, open plant produces uniform heads that are deep and domed with tight, small beads. This Seminis variety has resistance to hollow stem and brown bead. It is suitable for crown-cut packs, bunching or florets.

Also by Seminis, Contributor (PX 05121366) is a mid-maturing variety that has demonstrated adaptability for the warm season. Heads have a high dome with a medium-fine bead size and a shiny blue-green color. It shows increased tolerance to hollow stem. In California, Contributor has performed well for spring harvest in the San Joaquin Valley and in the warmer summer slots in the Santa Maria area.

Sakata’s Emerald Isle (SBC 8410) is a mid-maturing-type broccoli with a short branching habit, smooth dome shape and medium-small beads. It shows excellent uniformity and yield per acre.

An excellent performer, Expo (SBC 3520) by Sakata excels for both crown-cut and processing. A late-maturing variety, Expo has a tight, heavy dome, short bract and small, uniform, green beads. It performs well in conditions from warm to cool, overwinter and low light.

Seminis’ vigorous hybrid, Heritage, produces uniform crowns suitable for domestic fresh market or export use, and is versatile enough for bunching or florets. Its smooth, high-domed heads feature tightlybeaded dark green florets. With cool-season vigor, it shows intermediate resistance to downy mildew and has demonstrated outstanding holding ability.

Late-maturing Imperial (SBC 2519) performs best during long day conditions with moderate heat. This Sakata variety has a tight dome with small dark green beads. Imperial can be used for bunching, crown-cut or processing. It shows excellent postharvest shelf life.

For cool-season production, Ironman’s heads are deep, domed and firm. This Seminis hybrid variety suits both fresh market and processing. It has relative tolerance to hollow stem and cat-eye. Its uniform plant and narrow petioles render Ironman easy to work, harvest and clean.

Rijk Zwaan’s Tahoe RZ has high yield potential. It performs best under cool to warm conditions when mildew is not a problem. Drip or furrow irrigation produces the best heads. Its smooth, dense, high dome-shaped heads excel for both crowns and florets. A dark green, its small to medium beads are uniform.

The author is a writer-researcher specializing in agriculture. She currently resides in central Pennsylvania.