Direct-Seeding Techniques for Guayule Stand Establishment in West Texas

Abstract

A major limiting factor in the commercialization of guayule (Parthenium argentatum Gray) is the high cost of stand establishment. Presently, guayule stands must be established by transplanting seedlings from a greenhouse. Production costs could be lowered considerably by the development of direct seeding techniques. The objective of this study was to examine the effects of seed conditioning, planting depth, and mulch on guayule stand establishment by direct seeding in west Texas. Experiments were initiated on a Delnorte very gravelly loam (loamy-skeletal, mixed, thermic Typic Paleorthids) during July, August, September, and October of 1988 and 1989 at the Texas Agricultural Experiment Station Guayule Research Site near Ft. Stockton. Conditioned and raw seed were planted on raised beds at 25 seeds/ft, with a Gaspardo (Gaspardo, Tagiamento, Pordenone, Italy) SV255 pneumatic planter. Planting depths and methods included: (i) 0.4 in. deep followed by the planter presswheel, (ii) 0.4 in. deep followed by the presswheel and drag chain, and (iii) on the soil surface. Coarse vermiculite and bare soil comprised mulch treatments. The plots were sprinkler irrigated and kept moist during germination and emergence. The greatest amount of water (52–100%) was applied during the first 30 d after planting. Seedling density was greatest when conditioned seed was planted 0.4 in. deep. Vermiculite mulch was beneficial only with surface planting when rainfall occurred immediately after planting. Successful seeding in west Texas required planting conditioned seed at least 0.4 in. deep during late spring and summer.