Cultivation of C 3 and C 4 crops in semi-arid regions will be severely constrained as global temperatures rise. Consequently, alternative crops need to be sought out that adapt well to heat and drought and are productive despite limited access to water. Traits, such as crassulacean acid metabolism (CAM), enable economically important species such as those in the Agave genus adapt to drought and high temperatures. The succulence and high efficiency of agaves, which enables them to produce biomass with little water, underscores their feasibility as an alternative crop for semi-arid regions, such as the Sonoran Desert in the southwestern U.S. In this paper, we offer a review of the suitability for cultivation of agaves via dryland farming, particularly by rock mulching techniques used by pre-Columbian, Sonoran Desert farmers. This analysis dovetails with information also provided on the biological traits of Agave and its historical and present utilization. Pre-Columbian, Hohokam dryland farmers used rock mulching in the form of rock piles to cultivate agaves. Rock piles acted as a type of mulch to harvest rainfall and to retain soil moisture, which allowed the Hohokam to intensively cultivate agaves during multi-year droughts. Remains of Hohokam rock mulching for agave production can be found at archaeological sites in central Arizona, which provides evidence of the utility of dryland farming and ancient agricultural innovation to reconcile water scarcity in the region. Moreover, the use of rock piles likely bolstered Agave productivity in marginal lands. Although little is known of historic rock mulching to cultivate agaves and its biological implications on plant productivity we suggest its application as a dryland farming model could be a sustainable strategy in the U.S. Southwest.

Background and Scope Crassulacean acid metabolism (CAM) is an intriguing physiological adaptation in plants that are widespread throughout many ecosystems. Despite the relatively recent mechanistic understanding of CAM in plant physiology, evidence from historical records suggest that ancient cultures in the Americas also recognized the value of CAM plants. Agave species in particular have a rich cultural legacy that provides a foundation for commercially valued products. Here, we review that legacy and potential relationships between ancient values and the needs of modern-day climate adaptation strategies. Conclusions There are many products that can be produced from Agave spp., including food, sugar, fiber, and medicines. Traditional knowledge about agricultural management and preparation of plant products can be combined with new ecophysiological knowledge and agronomic techniques to develop these resources in the borderland region of the southwest US and Mexico. Historical records of pre-Columbian practices in the Sonoran desert and remnants of centuries-old agriculture in Baja California and Sonora demonstrate the climate resilience of Agave agriculture. Commercial growth of both tequila and bacanora indicates the potential for large-scale production today, but also underscores the importance of adopting regenerative agricultural practice in order to accomplish environmentally sustainable production. Recent international recognition of the Appellation of Origin for several Agave spp. produced for spirits in Mexico may provide opportunities for agricultural diversification. In contrast, fiber is currently produced from several Agave species on many continents. Projections of growth with future climate change suggest that Agave spp. will be viable alternatives for commodity crops that suffer declines during drought and increased temperatures. Historic cultivation of Agave affirms that these CAM plants can supply sugar, soft and hard fibers, medicines, and food supplements.