PPDL Picture of the Week
January 30, 2017
Wenjing Guan, Assistant Professor, Department of Horticulture and Landscape Architecture, Purdue University
Daikon radish is a member of Brassica family. It forms a
large white tap root like a giant carrot. The tap root (12 to 20 inches long
and 2 to 4 inches in diameter) penetrates into the soil leaving 2 to 6 inches
protruding above ground. Radishes are cool-season
crops. They are best grown with air temperatures in the range of 50 to 65°F. They grow fast,
forming a dense canopy in the fall. They
are winter killed when temperatures drop to low 20°F for a few consecutive nights.
Daikon radish is a common and popular vegetable consumed in
the southeast and Eastern Asia. The large and white roots have a favorable mild
flavor, very low calorie content and high Vitamin C content. Fresh or pickled diced
daikon roots are important ingredients in a variety of dishes and soups in Asia
cooking. Leaves are also consumed as green vegetables.
Although daikon radish is regarded as an ethnic vegetable,
and is not often present in food markets in the U.S., there is a growing interest
in planting daikon radish as a fall cover crop because of its multiple
agronomic benefits. Thanks to the strong and deep tap roots, daikon radish has
been approved as an effective tool to reduce soil compaction. Studies have shown
that it was four times more effective to help corn roots to penetrate compacted
subsoil than winter fallow, and two times more effective than a rye cover crop.
Daikon radish is also a great tool for weed suppression. A well-established
daikon radish field can eliminate weed emergence in the fall and winter. The
fast growth and heavy nitrogen feeding characteristics make Daikon radish a desirable
N scavenger. After winter kill, daikon radish decomposes rapidly. Because they
do not need to be killed or incorporated, there is no delay in spring field operations.
However, as nitrogen from decomposed daikon radish is released in a short
period of time, it is important to plant crops early to take advantage of
the flush of nitrogen and to prevent nitrogen leaching.