Author
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Glaz, Barry |
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Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/1/2005 Publication Date: 9/12/2006 Citation: Glaz, B.S. 2006. Sugarcane growth, morphological, and photosynthetic responses to water-table depths. Journal of Sustainable Agriculture 28(3):77-97. Interpretive Summary: Sugarcane, the primary crop on the organic soils of the Everglades Agricultural Area in Florida, intermittently is exposed to undesirably high water tables and short-duration floods. Two experiments, each about 13 weeks in duration, studied young sugarcane growth, morphological and photosynthetic responses to water-table depths. Eight equally spaced water-table depths from 5 to 33 cm were maintained in large pots. Leaf and stalk dry weights declined linearly as the water-table approached the soil surface. During its growth, sugarcane usually has several large and small tillers sprouted from the same bud. The weight of the large tillers in this study was about 20 times more than that of the smaller tillers. More importantly, large tiller number was the morphological character that best explained leaf and stalk weight changes due to water-table depth. At the lower water-table depths (5-23 cm), increases in stalk diameter also corresponded to increases in leaf and stalk weights. Results of this study suggest that to analyze high-water tolerance of sugarcane genotypes and agronomic practices while sugarcane is young, large tiller number and secondly, stalk diameter, would be two important characteristics to examine. Identification of practices and genotypes tolerant to high water tables will help sustain sugarcane production in Florida and enable farmers in the Everglades Agricultural Area to reduce drainage to public canals. Improved soil conservation and less export of phosphorus to the Everglades would result from the ability to sustain yields at higher water tables. Technical Abstract: Sugarcane (Saccharum spp.) is the primary crop on the Histosols of the Everglades Agricultural Area (EAA), where undesirably high water tables are increasing in occurrence and duration. Improved understanding of sugarcane responses to these conditions could help develop cultivars and agronomic strategies to sustain high yields. The purpose of this study was to evaluate the effects of water-table depths of 5 through 33 cm on growth, morphological characters, and single-leaf net photosynthetic rate of young sugarcane. In the spring and late summer of 2002, pots were filled with organic soil from the EAA and maintained at water-table depths of 5, 9, 13, 17, 21, 25, 29, and 33 cm. Plant height and Ps were measured outdoors, usually weekly, on sugarcane cultivar CP 80-1743, previously identified as having the most yield reduction among nine cultivars exposed to a summer water-table depth of 15 cm. Each experiment was harvested about 13 wk after planting. In grams per square meter, leaf and stalk weights increased by 9.1 and 12.2, respectively (spring experiment), and by 5.3 and 4.6, respectively (late-summer experiment), for each cm increase in water-table depth. In both experiments, large-tiller number increased by 0.2 for each cm increase of water-table depth, over the range of water tables, and stalk diameter increased as water-table depth increased from 5 through 23 cm. Quantifying tiller number and stalk diameter in young plants should facilitate identification of sugarcane genotypes and agronomic practices with improved tolerance to non-flooded, high water-table depths if responses of CP 80-1743 are representative. |
