Biomass Production, Nutritional and Mineral Content of Desiccation-Sensitive and Desiccation-Tolerant Species of Sporobolus under Multiple Irrigation Regimes

The development of low‐water‐input forages would be useful for improving the water‐use efficiency of livestock production in semi‐arid and arid regions. The desiccation‐tolerant (DT) species Sporobolus stapfianus Gandoger and two desiccation‐sensitive (DS) species, Sporobolus pyramidalis and Sporobolus fimbriatus (Trin.) Nees. (Poaceae), were evaluated for aerial biomass production and seed productivity under three different irrigation regimes. Sporobolus stapfianus displayed the least biomass production, whereas S. pyramidalis and S. fimbriatus produced up to 3.8‐ and 11.2‐fold greater dry biomass, respectively, at the highest irrigation rate of 12 334 l (0.01 acre‐feet). Sporobolus fimbriatus and to a lesser extent S. pyramidalis showed significant increases in biomass production in response to increased irrigation rates, whereas S. stapfianus did not. Sporobolus pyramidalis and S. fimbriatus exhibited 3.2‐ and 6.0‐fold greater seed production, respectively, in response to increased irrigation rates, whereas S. stapfianus showed only a 1.4‐fold increase. All Sporobolus species possessed forage quality traits (e.g. crude protein, fibre content) comparable to those of timothy, a forage grass grown widely in the Great Basin in the western United States. Micronutrient content exceeded the minimum requirements of beef cattle, without surpassing tolerable limits, with the exception of zinc, which appeared low in all three Sporobolus species. The low water requirements displayed by these species, combined with their acceptable forage qualities, indicate that these grasses have the potential to serve farmers and ranchers in semi‐arid and arid regions of the western United States where irrigation resources are limited.