Biomass production of 14 accessions of cactus pear (Opuntia spp.) under semi-arid land conditions

Increased food, feed, and biofuel demands of the future will require a greater reliance upon crop production systems in arid and semi-arid regions around the world. Diminishing freshwater resources and hotter and drier climatic conditions will also necessitate the use of highly drought tolerant and water-use efficient crops. Cactus pear (Opuntia ficus-indica) is a low-water input, climate-resilient crop capable of high biomass production due to its use of crassulacean acid metabolism (CAM). Cactus pear produces both food and forage/fodder, a wide variety of high-value byproducts, and serves as a bioenergy feedstock for biogas or bioethanol production. Here, we evaluated the biomass productivity of 14 Opuntia spp. accessions from the National Arid Land Plant Genetic Resources Unit (NALPGRU) in Parlier, CA under semi-arid conditions with a planting density of 6667 plants ha⁻¹ over a 3-year period to identify high-yielding biomass producers. Mean annual cladode fresh weight (CFW) (73.7 Mg ha⁻¹ year⁻¹), cladode dry weight (CDW) (5.2 Mg ha⁻¹ year⁻¹), and cladode count (CC) (10.5 cladodes plant⁻¹) increased by 2.9-, 2.8-, and 2.8-fold in year 3 compared with year 1. PARL 845, hybrid no. 46 (O. ficus-indica × O. lindheimerii), showed the highest annual mean CFW (152.8 Mg ha⁻¹ year⁻¹), CDW (13.3 Mg ha⁻¹ year⁻¹), CC (22.1 cladodes plant⁻¹), and dry matter content (DMC, 11.2%) among all accessions tested. Non-hybrid accessions PARL 242 (O. cochenillifera), PARL 582 (Opuntia sp.), and PARL 584 (Opuntia sp.) showed 100% cladode establishment rates and CDW productivity of >6 Mg ha⁻¹ year⁻¹. Such biomass productivity results indicate that cactus pear displays great potential as a crop with many uses with lower water inputs than conventional crops for arid and semi-arid environments.