Okra (Abelmoschus esculentus ‘Clemson Spineless’) was grown on an Orangeburg sandy loam soil in Shorter, AL. Okra was direct-seeded in single rows. Treatments consisted of five mulch colors: black, white, red, silver, and blue installed either with or without spun-bonded row cover. Soil temperatures were 4 to 7 °C lower than air temperatures in all treatments. The use of darker (black, blue, red) -colored plastic mulches increased early and total yield of okra compared with bare soil with and without row cover. Increased soil and air temperatures did not always correlate to an increase in yield. It can be concluded that the use of dark plastic mulch is advantageous to growers of okra in climates that do not have cool springs, but the added use of row covers to plastic mulch has no effect on growth and yield. The profit of marketable okra produced using a row cover was $1.37 versus $1.35 per pound without a cover in 2003 and $1.28 versus $1.29 per pound in 2004. Blue plastic mulch is ≈$0.08 per foot more expensive than black plastic. Our data do not show an economic advantage for blue over black mulch for okra, but the positive effect cited by other authors may be more pronounced with leafy vegetables.

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BREAKING SEED COAT DORMANCY WITH PHYSICAL AND CHEMICAL METHODS IN TAMARIND (TAMARINDUS INDICA L.) SEEDS

In Miami, Florida, 95% of residential and 33% commercial soils exceed the Florida Department of Environmental Protection goals for cleanup of arsenic contamination. Ornamental plants have not been fully investigated as a mechanism for phytoremediation of low level As contaminated soil. This study evaluates nutrient uptake by ornamental plants grown in a hydroponic system containing concentrations of 0, 10, 20, 30, 40, 50 or 70 uM As (0.0, 0.75, 1.5, 3.0, 3.75, 5.25 mg•L −1 As, respectively). Uptake of Ca, K, Mg and Mo was likely influenced by the toxic effect of As on root functions. Arsenic had little effect on Ca, K and Mg transportation to the shoot at any but the highest As exposure rate. Tissue P concentration was similar to or higher than that found in controls and As competition with P uptake occurred at 70 uM As only. Tissue sulfur initially increased then subsequently decreased at 70 uM As where uptake could no longer supply enough S for both detoxification and normal metabolic needs. The effect of As on plant B was likely a result of membrane leakage and overall tissue damage leading to a reduction in transpiration. Arsenic induced Fe deficiency was likely the primary cause of chlorosis; however, As induced reduction in Zn, Mn or Mg contributed to chlorosis. Copper use in cellular functions was very efficient; nevertheless, Cu deficiency was one of the initial effects of As toxicity. Differences in mineral uptake reflect the plant's attempt to detoxify As (i.e. increase in S for S-containing As chelators), mitigate damage to the cell (i.e. Ca to repair leaky menbranes) or continue cellular functions through alternative pathways (i.e. Fe superoxide dismutases to replace the function of Cu/ZnSOD).

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