STP1078

    Effects of Spray Oils on Temperature, Net Gas Exchange, and Phytotoxicity of Citrus Leaves

    Published: Jan 1990


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    Abstract

    Three types of horticultural spray oils (Sunspray 7N, Sunspray 9N, and VOLCK Supreme Spray) were used to prepare spray mixtures of 1, 2, and 4% (V/V) oil plus emulsifier in water. The 50% distillation temperatures (50% DT) of the oils were 224, 235, and 247°C (435, 455, and 476°F), respectively. The mixtures were applied to the fully expanded young leaves of 2-year-old containerized ‘Valencia’ orange trees in 2 tests. In the first test, leaves on different plants were dipped in agitated oil mixtures and after one day, under sunny conditions, their leaf temperature (T1, infrared thermometer) and stomatal conductance (Gs, diffusion porometer) were measured. There was no significant effect of oil DT on T1 or Gs. However, averaged over all DTs of oil, the 4 and 2% rates significantly decreased G below that of the 1% rate. In the second test, the 1 and 4% oil mixtures and an emulsifier only solution were uniformly sprayed on both surfaces of the leaves with a hand atomizer. Three to 5 days later, stomatal conductance, CO2 assimilation (A), and dark respiration (R) of sprayed leaves were determined, using an open gas exchange system in the laboratory. Neither oil DT nor oil concentration had a significant effect on G5 or A; however, R was highest with Sunspray 7N-1% and lowest with Sunspray 9N-4% treatments. In both tests, no visible phytotoxicity was observed after 3 months under glasshouse conditions.

    Keywords:

    petroleum spray oil, citrus, phytotoxicity, stomatal conductance, CO, 2, assimilation, dark respiration


    Author Information:

    Salyani, M
    Assistant Professor of Agricultural EngineeringProfessor of Plant PhysiologyProfessor of Entomology, The University of Florida, IFAS, Citrus Research and Education Center, Lake Alfred, FL

    Syvertsen, JP
    Assistant Professor of Agricultural EngineeringProfessor of Plant PhysiologyProfessor of Entomology, The University of Florida, IFAS, Citrus Research and Education Center, Lake Alfred, FL

    Knapp, JL
    Assistant Professor of Agricultural EngineeringProfessor of Plant PhysiologyProfessor of Entomology, The University of Florida, IFAS, Citrus Research and Education Center, Lake Alfred, FL


    Paper ID: STP25373S

    Committee/Subcommittee: E35.22

    DOI: 10.1520/STP25373S


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