Physiological and Morphological Effects of High Water Tables On Giant Reed (Arundo donax), Elephant Grass (Pennisetum purpureum), Energycane and Sugarcane (Saccharum spp.).

Increasing demand for renewable energy sources has led to interest in high-biomass crops. Species that have been proposed as well-suited for biofuel production in the Everglades Agricultural Area (EAA) of Florida include Giant Reed (Arundo donax), Elephant Grass (Pennisetum purpureum), Energycane (Saccharum spp.), and Sugarcane (Saccharum spp.). Our objectives were to evaluate how high water table conditions in the EAA may affect the morphology and physiology of these 4 genotypes. The 4 candidate genotypes were grown in a greenhouse under 3 water tables, defined by distance from the soil surface. Two constant water tables (-16cm and -40cm) along with a flood cycle (2 weeks of flood followed by 2 weeks at -40cm) were utilized. The genotypes used were CP 89-2143 (Sugarcane), L 79-1002 (Energycane), Merkuron (Elephant Grass), and wild type (Arundo). The 4 genotypes were grown under each of the 3 water tables in 4 replications, in a randomized complete block design. This was carried out for 3 trials, a plant cane, a ratoon, and a successive plant cane. Reductions in dry matter yield were observed among genotypes subjected to periodic flooding.  In plant cane total dry matter yield was reduced, in the flood water table relative to the -40cm constant, by 37% in Arundo, 52% in Elephant Grass, 42% in Energycane, and 34% in Sugarcane. In the ratoon crop reductions in dry weight, in periodically flooded water tables relative to -40cm constant, were 29% for Arundo, 42% for Elephant Grass, 27% for Energycane, and 62% for Sugarcane. In plant cane, and successive plant cane, average total dry weight was greatest for Elephant Grass whereas ratoon total dry weight was greatest for Energycane. Aerenchyma presence and volume increased with higher water tables. Our results indicate variable tolerance to flood among these genotypes.