Growing Seeds of Forages Outside Their Regions of Use

CARLTON S. GARRISON AND RAYMOND J. BULA.

REGARDLESS of how superior a new variety of grass or legume may be, it is of no value until seed of it is available and planted.

Limited supplies of seeds of new varieties retarded their use for many years or, American farms. Because of difficulties associated with increasing the seed, some superior varieties of forage fell by the way because adequate supplies of seeds were never made available. As recently as 1948, less than 2 percent of all the grass and legume seeds planted in this country were of improved varieties.

The largest acreages of alfalfa, red clover, timothy, orchardgrass, bromegrass, alsike clover, hairy vetch, crimson clover, and other crops are in the Central, Eastern, and Southern States, but they are used primarily for forage or soil improvement. Their yields of seeds there often are low and of poor quality, and seed production tends to be an incidental farm enterprise. In sections where a crop is grown extensively for forage, moreover, it is not easy to locate fields eligible to produce certified seed because of the problem of isolation from contaminating sources and volunteer plants.

The production of seeds of the improved varieties therefore has shifted more and more to the specialized seed-producing areas in the Western States, where a dry, sunny climate and controlled irrigation make conditions ideal for growing and harvesting the seeds and yields are dependable.

To utilize these new seed-growing regions, plant breeders, seed-production specialists, and State seed-certifying agencies had to develop procedures for growing seeds of forage varieties outside the area where they were bred and where they are used what is referred to as the variety's region of adaptation.

These procedures have made it possible to increase rapidly the seeds of forage varieties in the West and to maintain at the same time their superior characteristics. For instance, the special procedures have been included in the certification standards for several crops alfalfa, birdsfoot trefoil, clovers, and some grasses.

PROCEDURES developed for the production of certified alfalfa seed are typical of the limitations for growing certified seed of an improved variety outside its region of adaptation.

Three requirements must be met.

Seed fields must be planted with foundation or registered seed that is produced in the variety's region of adaptation. Seed from these fields is labeled "certified" regardless of whether foundation or registered seed was planted.

Only one generation of seed increase is permitted outside a variety's region of adaptation.

Certified seed production is limited to stands not more than 6 years old. In practice, the seed is harvested from stands usually not more than 3 or 4 years old.

The same limitations set up for alfalfa apply to varieties of birdsfoot trefoil when seed is grown outside their regions of origin.

The certification requirements for red clover differ slightly from those for alfalfa and birdsfoot trefoil. Changes in varietal characteristics are more pronounced in red clover than in alfalfa. Specific requirements in the certification standards consequently must minimize any changes that may result from the effect of daylength, temperature, management practices, age of stand, and diseases during the process of seed multiplication.

Kenland red clover, for example, has resistance to southern anthracnose (Colletotrichum trifolii), a disease of major importance in Kentucky, Indiana, Illinois, Ohio, Virginia, Tennessee, Maryland, and Delaware. It has not been found in the West. When Ken-land red clover is grown there, the nonresistant types usually are heavy seeders. Thus there is a shift toward plants that are poorly adapted to eastern and central conditions. The requirement that only two generations of increase be grown from breeder seed insures that Kenland does not lose its resistance to southern anthracnose.

Three requirements pertain to growing seed of red clover varieties outside their regions: Only two generations of increase are permitted from breeder seed one each of foundation and certified seed. Only two seed crops can be harvested from a planting in the same or consecutive years. Foundation seed cannot be produced on seeding-year stands for varieties, such as Dollard and Lakeland, that are adapted to the Northern States.

UP-TO-DATE methods and technology have made it possible to increase rapidly the supplies of seeds of an improved variety. Planters can have more of the seeds sooner.

The success of these procedures is illustrated by the production of seeds of six varieties of alfalfa within and outside the regions of adaptation. Four: DuPuits, Narragansett, Ranger, and Vernal are recommended in the North Central and the Northeastern States. Atlantic and Buffalo are used widely in the Central, Eastern, and Southern States.

The total production of certified seed of the six varieties has amounted to more than 470 million pounds, 85 percent of it outside the regions of adaptation. California alone produced more than 375 million pounds.

More than 65 percent of our alfalfa acreage was planted with the six varieties in 1958; the acreage would have been smaller had not large amounts of seed been grown outside the region of adaptation. Farmers thus got dividends from varieties that have greater persistence, give better yields, and are more resistant to bacterial wilt.

In the same way, supplies of seeds of Dollard, Kenland, and Pennscott red clovers have been built up rapidly by producing certified seed in the specialized areas in the West. The practice started in the late 1930's for such varieties as Cumberland and Midland, but the greatest progress occurred after 1950. The National Foundation Seed Program helped greatly in the essential work of coordinating the production and distribution of the foundation seed.

More than 33 million pounds of certified seeds of Dollard, Kenland, and Pennscott red clover have been grown; 98 percent of it in the West, mostly in Washington, Idaho, and Oregon. Farmers in the Central and Eastern States, where these varieties are adapted, depend on supplies of western-grown seeds.

Certified seed of Pennlawn red fescue, Penncross and Pennlu bentgrasses, Pennlate and Potomac orchardgrass, Saratoga bromegrass, Essex timothy, Romack field pea, Dixie crimson clover, Pilgrim Ladino clover, Auburn vetch, Merion Kentucky bluegrass, and Chesapeake red clover also is produced in the West.

Without the specialized seed production in the West, commercial supplies of seeds of many grass and legume varieties would not exist. The physiological and genetic characteristics of many forages complicate their culture for seed production in those areas, however.

This is not strange when we consider the genetic variability in the cross-pollinated forage varieties and the fact that certain plant types (genotypes) may set more or fewer seeds than expected when subjected to different environments. During the multiplication of seeds, climatic conditions and farm-management practices in the western seed-growing sections can cause changes in a grass or legume variety developed in the Eastern States. Through each generation of seed increase, Nature closely screens the plant population in a variety. Some plant types may succumb to various elements of environment, like climate, or improper watering, or mowing at the wrong time. Others may produce few seeds to perpetuate themselves in the next generation. Such effects may show up strongly in varieties when seeds are grown in different places, for some regions may favor specific segments of the plant population. The results can be so pronounced as to affect the performance of the variety itself.

How, then, can one predict the reaction of a variety to varying environmental and management pressures?

The answer is simple. We cannot make such predictions, because we do not understand fully the flowering response of forage species. The growth and flowering habits of plants become highly important, however, when they are grown for seeds, particularly outside the regions of adaptation.

DIFFERENCES in daylengths from north to south affect the flowering of many forage species. Ladino clover produces an unlimited number of flowers in the Northern States but flowers sparsely south of the line running through Savannah, Ga., and Shreveport, La. That is roughly 32 latitude, where the longest day is a little more than 14 hours. Ladino clover needs more than 14 hours of daylight to flower heavily.

The flowering habit of certified seed of Ladino clover produced in four Western States was studied at the University of Illinois by J. A. Jackobs and C. N. Hittle. The seeds produced in California had fewer blooms than the seeds produced in Idaho, Oregon, and Washington.

Variations in flowering response to overwinter temperatures and day-lengths among the parental clones of Pilgrim Ladino clover have been reported by scientists at the California and Washington Agricultural Experiment Stations. When the 21 clones used in their study were established vegetatively not by seed, at Davis, Calif. (38 latitude), and Prosser, Wash. (46 latitude), flowering was more uniform and persisted longer at Prosser, where the days are longer during the growing season.

The degree and likelihood of a genetic shift in Pilgrim Ladino clover therefore would be much greater in seeds produced in California than seeds produced in Washington.

The season, of course, determines the number of hours of daylight the plants get in the field. As days get longer from December 21 to June 21 and shorter after June 21, the effect on the flowering habit of red clover is marked.

These seasonal effects on Kenland and Pennscott were studied by men in the Department of Agriculture and the Indiana Agricultural Experiment Station. Nearly all plants established as spaced plants in rows in mid-May had flowering stems and produced seed by late October. Later seedings, up to mid-July, gave a smaller percentage of flowering plants. Fewer than 1 percent of the plants from the mid-July seedings produced flower stems, and none produced mature seeds.

This flowering pattern coincides with the change in daylength from mid-May to mid-July. The May seedings are well established by the time they are exposed to the longest days after mid June. The percentage of flowering plants is high. On the other hand, the mid-July seedings are exposed to the shortening days of July and August. These daylengths are not effective in stimulating red clover to produce flowering stems.