Agronomic evaluation of prospective new crop species IV.Dimorphotheca andOsteospermum — sources of dimorphecolic acid

Abstract

Five species ofDimorphotheca, seventeen species ofOsteospermum, and one species each ofCastalis andChrysanthemoides were evaluated at Chico, California for crop potential as a source of dimorphecolic acid. Several species includingD. sinuata were highly susceptible to a number of diseases. Date of planting strongly influenced flowering period ofD. sinuata andD. pluvialis. D. cuneata showed the most promise for crop development. It had limited disease, relatively good seed retention and cold-tolerance, and considerable variability. With improved disease resistance,D. cuneata could be handled as a perennial seed crop. Its lightweight seed, an important disadvantage, is associated with a high proportion of winged to unwinged seeds.Osteospermum caulescens, O. ecklonis, andO. muricatum also have characteristics that favor crop development.O. ecklonis probably could be handled effectively as a winter annual. Seed of these three species had bushel weights of 30 to 41 pounds, compared with four to five pounds forD. cuneata andD. sinuata. Some preliminary germination work showed seed dormancy, which is probably associated with an after-ripening requirement. Overall, the agronomic characteristics that need improvement were disease resistance, seed retention, and seed form. Prospects for agronomic improvement of the most promising species should be good, because variability was evident even in small test populations.