Submitted to: American Journal of Agricultural and Biological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2010
Publication Date: 11/26/2010
Citation: Zhao, D., Glaz, B.S., Comstock, J.C. 2010. Sugarcane Response to Water-Deficit Stress during Early Growth on Organic and Sand Soils. Amer. J. of Agr. and Biological Science. 5(3):403-414.
Interpretive Summary: A long-term cooperative effort of the USDA-ARS, University of Florida, and Florida Sugar Cane League, Inc. is to develop new sugarcane cultivars for Florida. During the past 33 years, this program has been more successful at developing high-yielding cultivars for the organic (muck) soils which comprise about 80% of Florida’s sugarcane than for the remaining 20% on sand soils. Researchers hypothesize that the lower water-holding capacity of the sand soils may be a major reason for the reduced success at cultivar development for these soils. A greenhouse study was conducted to compare sugarcane response to water deficit stress during a part of formative growth phase of sugarcane on each soil and to determine growth and physiological traits that may be used to identify varieties with water stress tolerance. Treatments included typical muck and sand soils (collected from sugarcane production fields) and two water regimes (well watered and water-deficit stress). Sugarcane cultivar CP 80-1743 was planted in pots which were fertilized with N, P, and K based on soil analyses. All pots were well watered before initiating the water stress. Starting at 58 days after planting, water was withheld from the water stress pots. During the stress period, relative water content, proline content, and photosynthetic components of the top visible dewlap leaves were measured along with plant growth. Final green leaf area and shoot biomass were determined 27 (in 2009) or 22 (in 2010) days after initiating the water stress treatment. Stress symptoms of sugarcane plants appeared about 7-10 days earlier on sand soil than on muck soil. Water stress reduced stomatal conductance, photosystem II photochemical efficiency, photosynthesis rate, and green leaf area, resulting in reduced shoot biomass on sand soil. There was a much greater physiological impact of water stress on sugarcane on sand than on muck soils suggesting that improving cultivar resistance to water stress while improving irrigation will help improve yields on sand soils. Leaf stomatal conductance, photosystem II photochemical efficiency, and photosynthesis rate of sugarcane may be used for early detection of water stress. Development of genotypes with more tolerance to water stress during the formative growth phase of sugarcane and better irrigation management based on plant physiological status may improve sugarcane production on sand soils.
Technical Abstract: Approximately 20% of sugarcane (Saccharum spp.) is grown on sand soils in south Florida, USA. Sugarcane yields in the region linearly increased in last 33 years on organic (muck) soils, but not on sand soils. Water deficit during the formative growth phase on sand soils probably limits sugarcane yields. A greenhouse study was conducted in 2009 and 2010 to evaluate the physiological and growth responses of sugarcane to water-deficit stress during formative growth. Treatments included organic (muck) and sand soils and two water regimes Well Watered (WW) and Water-Deficit Stress (WS). Sugarcane cultivar CP 80-1743 was planted in pots and fertilized with N, P and K based on soil analyses. All pots were well watered until 58 days after planting, when water was withheld from the WS pots. During the WS treatment, plant growth rate, leaf Relative Water Content (RWC), proline content and photosynthesis components were measured. Final tillers, Green Leaf Area (GLA) and shoot biomass were determined 27 (in 2009) or 22 (in 2010) days after initiating the WS treatment. Stress symptoms of sugarcane plants appeared 7-10 days earlier on sand soil than on muck soil. Water stress reduced stomatal conductance (gs), Photosystem II Photochemical Efficiency ('PSII), leaf Photosynthesis rate (Pn), the number of tillers and GLA, resulting in reduced shoot biomass, especially on sand soil. Neither leaf RWC nor proline content was a sensitive WS indicator. Nondestructive measurements of physiological traits of gs, 'PSII and Pn during the formative stage may be useful for early detection of water stress in sugarcane.