Guayule prefers areas with annual precipitation between 280 and 640 mm, but for
maximum rubber yields, moderate to heavy applications of irrigation are necessary.
Dry matter production and resin and rubber yields have been shown to increase
proportionally with increased water availability (Nakayama et al., 1991).
Salt tolerance of the established crop is higher than that of alfalfa and is almost as
tolerant as upland cotton (salinity levels up to 4.5 dS m-1 are acceptable). Higher
concentrations of soluble salts in irrigation water will limit water availability to the
plant and reduce plant growth.
Irrigation will affect both scrub yields and also rubber accumulation. So far, no direct
correlations between water supply, dry matter yield and rubber yield have been
established. Although sufficient water is required to allow crop growth, guayule is
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quite resistant to drought conditions. The plants will interrupt rubber accumulation,
but they survive extended periods of limited water availability.
Guayule is a low user of nutrients. Fertilisation requirements are highly dependent
on soil fertility. In general, application of nitrogen (18 - 210 kg ha-1) in combination
with irrigation increased plant biomass yield. Pests are not a major issue for
guayule.
A method to improve production of high molecular weight rubber by adding a growth
regulator has been described (Bauman, 1979). This method is also used to improve
latex production by Hevea, and needs further study.