Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 5/10/2010
Publication Date: 6/18/2010
Citation: Zhao, D., Glaz, B.S., Comstock, J.C. 2010. Identification of Physiological Traits for Early Detecting Water Deficit Stress in Sugarcane. American Society of Sugar Cane Technologists.
Technical Abstract: Sugarcane (Saccharum spp.) genotype selection has been more successful for organic (muck) than sand soils in Florida. Water deficit stress during its formative growth phase may limit sugarcane growth and yields on Florida sand soils. Therefore, identifying proper physiological traits will help scientists select genotypes with water stress tolerance and improve variety selection efficiency for sand soils. A greenhouse study was conducted to determine some physiological traits that may be used to select water deficit tolerant sugarcane genotypes. Treatments included muck and sand soils, two water regimes [well watered (WW) and water deficit stress (WS)], and two genotypes (CP 80-1743 and CP 01-2390). CP 80-1743 is a commercial cultivar for Florida muck soils and CP 01-2390 is an experimental line with superior agronomic performance on Florida sand soils but was not released due to susceptible to smut disease. These two genotypes were used to consider their performance on Florida muck and sand soils. The experiment was a split plot design with seven replications. Soil type and water regime were main plots and genotype was sub-plot. Single-bud stalk sections of sugarcane were planted in pots and fertilized with N, P, and K based on soil analyses. To ensure consistent conditions of soil water content and nutrients, the two genotypes were planted in each pot and labeled to indicate the genotypes. Thus, there were two plants per pot (one was CP 01-2390 and the other was CP 80-1743). All pots were well watered until 58 days after planting, when water was withheld from the WS pots. During the stress treatment, leaf relative water content (RWC) and proline content were measured weekly and leaf stomatal conductance (gs), photosystem II photochemical efficiency ('PSII), and leaf net photosynthesis rate (Pn) were determined every 3 or 4 days. Water stress significantly reduced leaf gs, 'PSII, and Pn. In contrast, leaf RWC and proline content were not sensitive WS indicators in this study. Photosystem II photochemical efficiency did, but either gs or leaf Pn did not differ significantly between the two genotypes. The effects of water stress on sugarcane plants were much greater on sand than on muck soils. These results suggest that physiological traits of leaf gs, 'PSII, and Pn can be used for early detecting sugarcane plant water stress and for stress tolerant genotype screening. Improving genotypic resistance to water stress, in addition to improving irrigation management, will increase sugarcane yields on sand soils.