|MadSci Network: Botany|
Hi, For most of the plants, sulfate(SO4) is the absorbed form of sulfur in plants, and I think the powder you described was pure sulfur (S). It is hard to assimilate. To test the effect of sulfur on plant, it is better to use sulfide such as K2SO4. In general, the assimilated sulfur is used for synthesis of protein, so in lack of sulfur for a long time will cause problem for plants. One of the symptoms is that the veins turn yellow, maybe because the veins are active in transporting sulfur in plants. Plants mainly use roots to absorb sulfate from soil, but under some conditions, such as high H2S concentration in air, the plants will be badly harmed, because high H2S will led to formation of sulfuric acid which is easy to destroy plant tissue. This is similar to the result of industry pollution. Hope these can be helpful. Reference: Plant Physiology( 2th edition ), Taiz & Zeiger, 1999 ( textbook ) David Hershey adds the following: If you are required to use the powdered sulfur in your experiment, then you could add it to potting soil in various amounts and grow plants in the potting soil treated with different amounts of sulfur. In moist soil, sulfur is converted by sulfur bacteria, such as Thiobacillus, into sulfuric acid, which lowers the soil pH (Brady, 1984). You can measure the soil pH with a pH meter or pH paper and see how soil pH affects plant growth. Powdered sulfur is also a fungicide so you might simply sprinkle sulfur on the plant leaves and see if it is toxic or effective against fungal diseases (Wyman, 1986). Another common experiment is to grow plants in hydroponics with and without sulfur in the nutrient solution and produce sulfur deficiency symptoms (Hershey, 1995). Hydroponic experiments would not use powdered sulfur however. References: Brady, N.C. 1984. The Nature and Properties of Soils. New York: Macmillan. Hershey, D.R. 1995. Plant Biology Science Projects. New York: Wiley. Wyman, D. 1986. Wyman's Gardening Encyclopedia. New York: Macmillan. (see fungicides)
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