Rubber content in different plant parts and tissues of Mexican guayule shrubs

Abstract

Knowledge of the rubber distribution in different plant parts may be useful in selection and in planning more efficient breeding programs. Rubber content and its distribution in the root, stem and branch and tissues (bark and wood) of guayule ( Parthenium argentatum Gray) were determined and correlated among the different plant characteristics. A total of ten accession of guayule were used. The analysis of variance showed highly significant differences for percent rubber among the accessions, in the bark and wood tissues. Significant differences were also found in the plant and tissue biomass. The interaction between tissues and plant parts was significant for their dry weights. The accessions 4597, 4144 and 4580 produced higher biomass, whereas the three entries 4599, 4580 and 4144 had the higher rubber concentration. Roots, stems and branches constituted 9.4, 5.5 and 85.1%, respectively of the total plant dry weight. The wood to bark ratio was 1.6:1. The wood and bark contained 17.6 and 82.4% of the total plant rubber, respectively. The rubber contents of the three plant parts and two tissues were significantly and positively correlated with the total plant rubber content.