Factors Affecting the Accumulation of Rubber in Seedling Guayule Plants

Abstract

1. Guayule seedlings of strains 593 and 4265 were grown to an age of about 6 months in two levels of light intensity, soil moisture, temperature, and available nitrogen and various combinations of these conditions. The dry weights, sugars, levulins, inulin, pentosan, resins, and rubber content of the plants were determined. 2. Dry weight of plants and percentages of determined constituents were generally higher on the high than on the low level of light intensity. 3. At high light intensity, plants grown at the high levels of temperature, soil moisture, and available nitrogen always showed a greater dry weight and, with one notable exception, a lower percentage of levulin, resins, and rubber than those grown at the low levels of these factors. The exception was the higher rubber percentage of the plants grown at high temperature in sand culture than of those grown at the low level. 4. Plants grown in sand culture at the high levels of available nitrogen, temperature, and light had the greatest dry weight ...