George A. White

Agronomic evaluation of prospective new crop species

Preliminary field evaluations for 162 species are reported. This work represents a portion of a team-oriented effort to develop new crops for American agriculture. These species are potential new oilseed sources of epoxy, crepenynic, erucic, and other fatty acids, and sources of seed gum, steroids, and pulp. Euphorbia lagascae andCephalaria setosa show the most promise for crop development as epoxy acid sources, but both require substantial improvement through breeding.Crepis alpina, a small-seeded species with excellent seed retention, is the best prospect for providing an oil rich in crepenynic acid. A selection and breeding program is under way. None of the species tested as erucic acid sources equalled the crop potential of crambe and selected Brassicas.Briza spicata, a small, moderately productive grass, is the richest known source of glycolipids.B. spicata has been grown successfully as a winter annual at several locations. Earlier maturity and better seedling vigor is needed inSatureja hortensis, a source of oil similar to linseed oil.Xeranthemum annuum, an attractive, winter annual and everlasting, is very good agronomically, but the use of the oil with its mixture of several fatty acids is not economically favorable.Solanum khasianum shows agronomic promise as a source of the steroid, solasodine.Cassia occidentalis, C. bonariensis, Crotalaria leioloba, andC. stipularia are productive potential seed gum sources. These species, especiallyCassia occidentalis, seem to be sufficiently good agronomically to justify intensive breeding. Of the various sources of pulp, emphasis is on kenaf because highyielding, well-adapted varieties are available.Crotalaria juncea merits breeding effort, and other species show sufficient promise for further evaluation.

Preliminary assessment of Crambe germplasm resources

SummaryCrambe abyssinica is a prospective crop as a source of erucic acid-rich seedoil. Studies on oil use, seed processing, culture, cultivar improvement, and disease resistance are in progress. Other species in the Section Leptocrambe also have high levels of erucic acid in their seedoils. Research on their oil composition and botanical agronomic characteristics is being initiated.World distribution of wild species and their association with specialized pests and pathogens point to southwestern Eurasia as the possible home of the genus Crambe. C. hispanica and certain other species are distributed in the mild Mediterranean area and C. abyssinica in northeast Africa and Turkey.

Agronomic evaluation of prospective mnew crop species II. The AmericanLimnanthes

Limnanthes is a potential seed oil source of long chain fatty acids. Agronomic evaluations in Alaska, California, Maryland, and Oregon indicate that theL.alba group has the best crop potential because of superior seed retention and erect growth habit. Experimental seed yields of 1700 kg/ha or more indicate that economically feasible yields on a commercial scale will be attainable, as continued study reveals optimum cultural practices and utilizes variability present in the various accessions. For the best seed yields,Limnanthes must be handled as a winter annual in California, Maryland, and Oregon but as a spring-seeded annual in Alaska.Limnanthes plants mature rapidly during hot weather; thus the timing of harvest is critical for maximization of seed yields. Further studies on seeding rates, weed control, and harvest methods are suggested.

Yield trials of steroid-producingDioscorea on Florida’s Everglades peat soils

Four steroid-bearing clones of Dioscorea tested in a replicated varietal trial on Everglades peat soil near Belle Glade, Florida, included three introductions of D. spiculiflora Hemsl. and one selection of D. composita Hemsl.On an acre basis, D. composita, P. I. 201783, produced over 21 tons of dry tubers and 1,049 lbs of crude sapogenins. Tuber and sapogenin yields front the highest producing D. spiculiflora, P. I. 252887, were approximately 1/3 and 1/2 respectively, of these amounts.Yield differences were not significant between plots harvested 2 1/2 and 3 1/2 years after planting. The failure of tubers to increase in size in the last growing season was attributed to the restriction on growth imposed by the high water table at the test site.

Plant germplasm acquisition and exchange

Plant germplasm is an essential element in crop production and improvement programs worldwide. In the U.S., this fact quickly became a stark reality for the first settlers to the east coast from Europe. Subsequently, government officials, recognizing a dearth of native crops, initiated modest efforts to introduce and test seeds and plants from abroad. In 1898, the U.S. Department of Agriculture established the Seed and Plant Introduction Section to provide for the worldwide acquisition of plant materials [1]. In the same year, new introductions were assigned Plant Introduction (PI) numbers and distributed to research stations and universities for testing. Data compilation for USDA Plant Inventories also started in 1898 and continues to the present. During the past 90 years, more than 518,000 PI numbers have been assigned and data have been compiled for 196 published inventories.

Agronomic evaluation of prospective new crop species. VI.Briza humilis—Source of galactolipids

Briza humilis Bieb., a low seed-yielding member of the family Gramineae, showed agronomic promise as a commercial source of galactolipids. The seed lipid contains about 80% galactolipids, compared to little, if any, in other evaluated species ofBriza. An obligate winter annual,B. humilis is a small, noncompetitive grass with good seed retention. Seed (caryopsis) yields ranged from 280 to 1,475 kg/ha. Clean threshing of the light-weight seed (0.5 g/1,000) proved difficult. Because yield and plant size varied, agronomic improvement should be possible.

Agronomic evaluation of prospective new crop species III.Crepis alpina — source of crepenynic acid

A single accession ofCrepis alpina, P.I. 326551 from Turkey, showed good agronomic potential for crop development. The seed oil contains more than 70 percent crepenynic acid. Seed retention and plant habit are excellent. Seed yields ranged from 11 7 to 1,800 kg/ha. Spring and fall plantings were successful at several locations. Fall plantings may be preferred because of earlier maturity. Since early seedling development is slow, weed competition may be severe. Direct combining should be feasible, but threshing problems might arise because of the small, long-beaked seed. Improvements in yield and other agronomic characteristics should be possible through breeding. More germ plasm would provide a broader base of plant variability.