Polymers control timing of seed germination.

Scientists at Landec Corp. (3603 Haven Ave., Menlo Park, CA 94025) have finished planting the company's Intellicoat relay cropping of wheat and soybeans at more than 50 commercial farms and research sites in the midwestern United States. Landec's wheat-soybean relay cropping system involves coating soybean seeds with the company's proprietary Intelimer polymer. The expanded field trials involved planting more than 900 acres of wheat and soybeans in nine states. The results of these trials will be available by the middle of autumn.

The polymers regulate the water uptake of the seed, and thus control the timing of seed germination. Prior tests conducted in Indiana, Ohio and Michigan demonstrated that Intellicoat soybean coatings achieve the targeted 20- to 25-day germination delay under a range of field conditions.

Based on prior results and the anticipated outcome of these expanded trials, company management believes its coating technology should provide a way for farmers to grow and harvest two crops on the same field in one year, creating significant financial benefit.

The novel relay cropping approach entails the planting of winter wheat in the late autumn, with the coated soybeans planted into the wheat the following May, when the emerging wheat is 8 inches to 12 inches tall. The coating prevents the soybean from germinating for 20 to 25 days while the wheat continues to grow and mature. The wheat is harvested in early July when the soybeans are only 6 inches to 10 inches high and therefore not tall enough to be damaged during the wheat harvest.

Following the wheat harvest, the established soybeans have enough moisture and sunlight to produce a healthy crop, which enables the farmer to harvest two crops in the same growing season off the same field. The company also has had a successful first year of sales for its initial Intellicoat seed coating products, MD 9100 and MD 9050. The coating delays the germination of the male inbred seed, which reduces the risk of split planting and improves pollination for seed production. Corn seed companies use these coatings to substantially reduce the risk in the production of hybrid corn seed.

In addition to the relay cropping system and coated delay inbred corn, Landec scientists have initiated field testing of a hybrid corn seed coating that allows farmers to plant three weeks to four weeks earlier than normal. An early planted hybrid corn seed would open up the planting window and give farmers much greater flexibility and reduce their risk during the critical planting period. This is especially important to the growing number of larger farm operations that have to plant large acreage in a very short planting window. Trials are being conducted in seven states in the midwestern United States, with planting dates as early as late March.

Patent. 5,129,180-Temperature-sensitive seed germination control. Issued: July 14, 1992. Inventor: Ray Stewart. Assigned to Landec Labs Inc., Menlo Park, CA. Coated organisms, particularly coated seeds, are discussed in the patent. The coating is comprised of one or more polymeric materials. These form a coating with a temperature-dependent permeability with respect to water permeability. The polymeric materials are relatively impermeable to materials, such as water, at cooler temperatures (less than optimum growth or germination temperatures). They are relatively permeable at higher temperatures (at or greater than optimum growth or germination temperatures). The variable permeability of the coating prevents imbibition at lower temperatures and allows it at higher temperatures. Coated seeds can be planted early in a planting season and undergo imbibition, then germination.

Further information. Natarajan Balachander; phone: [phone]; fax: [phone]; email: [e-mail].