Sugarcane Growth and Physiological Responses to Water Deficit Stress On Organic and Sand Soils.

Sugarcane (Saccharum spp.) genotype selection has been more successful for organic (muck) than sand soils in Florida, perhaps due to differences in water availability. A greenhouse study was conducted at Canal Point, Florida to compare sugarcane physiological responses to water deficit stress during early growth on each soil type.  Sugarcane cultivar CP80-1743 was planted in pots which were fertilized with N, P, and K based on soil analyses. Treatments included two soils (muck and sand) and two water regimes [well watered (WW) and water deficit stress (WS)] planted in a randomized complete block design with seven replications. All pots were well watered before WS was initiated. Starting at 58 d after planting, water was withheld from the WS pots. During the stress period, plant growth, leaf relative water content (LRWC), leaf proline content, stomatal conductance, and photosynthesis were measured every 3 or 4 d. Soil type significantly affected plant response to water stress. Neither leaf proline nor LRWC was a sensitive indicator of sugarcane water stress. Water stress reduced the number of large tillers, green leaf area (GLA), stomatal conductance, and photosynthesis, resulting in reduced shoot biomass. At 24 d after the stress treatment, the number of large tillers, GLA, stomatal conductance, and photosynthesis of the WS plants were reduced 33, 50, 51, and 48%, respectively, on muck soil and 83, 82, 72, and 84%, respectively, on sand soil compared with the WW treatments. There was a greater physiological impact of WS on sugarcane on sand than on muck soils.