The influence of Some Soil and Climatic Factors on Sapogenin Yields of Dioscorea

Abstract

Plants of two sapogenin-bearing Dioscorea species propagated by two different techniques, were tested at different locations in Puerto Rico over a 3-year period. In an experiment at Mayagüez plants grew best in a loose, well-drained soil, planted on flat beds rather than ridges, and without the addition of organic material (cachaza). In plots at Isabela, Corozal, and Adjuntas sapogenin yields were higher in the Isabela loam than in the heavier clay soils at the other locations. Plants propagated from stem cuttings gave better results in D. floribunda plantings; propagations from tuber pieces gave better results with D. composita. In these trials the propagation method and the effects of climate and soil influenced plant growth and tuber yields, but had little effect on the percentage of sapogenin developed in the tubers. Location effects on total sapogenin production resulted in most cases from differences in tuber yield, rather than in percentage sapogenin. These were the largest controlled experiments conducted with sapogenin-bearing species in Puerto Rico. Although these tests indicate that they are satisfactorily adapted to a wide range of conditions, it is clear that best yields are obtained in good, well-drained soils. Sapogenin yields were sufficiently high to be commercially valuable in all locations tested.