Effect of environmental conditions on growth and rubber production of guayule (Parthenium argentatum)

Abstract

Nine lines of guayule were grown in the field near Narrabri and Canberra. Rubber percentage and dry matter production were estimated after four years' growth. Although dry matter yield per plant was comparable in the two locations, the rubber content was higher at Narrabri. Rubber percentage was greater after winter than after summer, indicating that cool conditions were favourable for rubber accumulation. This was supported in phytotron studies where rubber percentage was much higher at 15/10 than 24/19�C day/night temperatures. In contrast, elongation of shoots was promoted by high temperature, high radiation conditions. In a phytotron study guayule transpired substantially less than wheat per unit leaf area. The agronomic consequences of these findings are discussed.