Hesperaloe water requirement and management for biomass production

Abstract Hesperaloe ( Hesperaloe funifera (Koch) Trel.) has potential as a new source of fibers for specialty papers. Agronomic research on Hesperaloe has been in progress since the 1980s, however, limited information is available on its water use requirement and yield response to irrigation. A study to assess the influence of water management on leaf yield and seasonal water use of Hesperaloe grown as a perennial crop was conducted during 1995–1999 in a flood-irrigated planting established from transplants in November 1994. Irrigation treatments evaluated were: (T1) irrigate when available soil water was 25–35% depleted in the top 0.6 cm of soil; (T2) irrigate at 40–50% depletion; (T3) irrigate at 50–60% depletion; and (T4) irrigate at 70–80% depletion. Treatments T1 and T2 resulted in the highest leaf yields, 93–94 Mg/ha fresh leaf weight, at the end of 5 years. Comparable yields for T3 and T4 were T1=77 and T2=46 Mg/ha. In 1999, the fifth year of production, T1 and T2 produced leaf yields of 34–36 Mg/ha. Average evapotranspiration (ET) for 1996–1999 was 753 mm/year for T1 and 676 mm/year for T2. Total ET in 1999 for T1–T4 was T1=830, T2=786, T3=727 and T4=517 mm. The peak ET rate was 4.34 mm/day and occurred in T1 during July 1999. Hesperaloe was observed to have a shallow, horizontal root system. The highest water use efficiency (WUE) achieved was 1.49 kg leaf dry weight per m 3 of water for T2 in 1997. Average WUE for T2 for 1996–1999 was 1.10 kg leaf dry weight per m 3 of water. In this study, managing water to maintain available soil water at 40–50% depletion resulted in maximum leaf yield and high WUE.