Effects of Field Storage on Guayule Rubber Quantity and Quality

Abstract

Abstract Irrigation treatments affected the amount of biomass produced, but not the NR percentage of the plant or the quality or quantity. Different guayule genotypes varied in their rate of rubber degradation over storage time. All lines tested in this experiment decreased in Mw by the end of the storage period, but degradation in some did not occur until the fourth week of storage. An increase in Mw of most lines was seen after the first week of storage, indicating that the enzymatic processes are still functioning beyond the first few hours of harvest, and for some lines, beyond the initial sample taken after one week of field storage. Other lines may follow this same pattern of degradation, but it was not detected by the sampling protocol in this study. Guayule lines 11605, 11619 and interspecific hybrid AZ101, when irrigated between 4 to 7 times per year (50 to 90 cm/year), harvested in early spring, and then stored in the field as whole plants for no more than 2 weeks, would yield optimum rubber quality and quantity (per acre) with little or no deterioration. Other lines in this study, 11604, N565, 593, and 11634, cannot be field stored for longer than 1 week without a loss of rubber quality and quantity based on these results. The variation seen in the different lines indicates two important points. First, the amount of time plants remain in the field following harvest is an important determinant of rubber quality and quantity. Secondly, selection for degradation characters should be possible for crop improvement.