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The Effect Of Selenium On Sulfur Uptake By Barley And Rice, Robert Mikkelsen, Hongfu Wan
The Effect Of Selenium On Sulfur Uptake By Barley And Rice, Robert Mikkelsen, Hongfu Wan
Robert Mikkelsen
Because of their chemical and physical similarities, plant uptake of sulfur and selenium are closely related. Barley and rice were grown in greenhouse solution culture to examine the synergistic interactions between sulfate and selenate in plant uptake. In the presence of low concentrations of solution sulfate, shoot and root yields were decreased with additions of selenate. However, when sulfate was present in elevated concentrations, no selenium-induced yield reductions occurred. A synergistic interaction between sulfate and selenate caused an increase in the shoot sulfur concentrations with increasing concentrations of selenate at low sulfate solution concentrations. At elevated sulfate concentrations, no synergism …
Biuret In Urea Fertilizer, Robert Mikkelsen
Biuret In Urea Fertilizer, Robert Mikkelsen
Robert Mikkelsen
Urea has become the leading form of N fertilizer worldwide. Historically there has been concern about biuret formed during the manufacturing of urea fertilizer and the potential adverse effect of biuret on plant growth. In this paper, the fate of biuret in soils and its phytotoxicity is reviewed. Biuret is mineralized by many soil micoorganisms, but the process is much slower than for urea. Excessively high biuret concentrations can damage seedlings and, like urea, should not be placed in close proximity to germinating seeds. Crop tolerance to biuret varies according to the plant species, soil conditions, fertilizer placement, and method …
Stratification Not Required For Tree-Of-Heaven Seed Germination, William R. Graves
Stratification Not Required For Tree-Of-Heaven Seed Germination, William R. Graves
William R Graves
Tree-of-heaven (Ailanthus altissima (Mill.) Swingle) seed germination and shoot dry weight were determined after stratifying samaras at 5 and 25 °C for up to 28 days. Seeds of samaras stratified at 5 °C for 0, 4, and 12 days showed 70, 77, and 96% germination, respectively, 7 days after sowing. Fourteen days after sowing, 90% of nonstratified seeds had germinated, but shoot weight of nonstratified seedlings was 16% less than that of seedlings from fruit stratified at 5 °C for 12 days. Germination 7 days after sowing was greater after stratification at 5 °C than at 25 °C, but the …