By Sharpton Toussaint and Christopher Vincent
Kaolin particle film is a promising grove management technique for pest control and growth enhancement. The optimal rates to use to improve water use and growth in citrus trees remain an important area of investigation.
Citrus leaves are prone to water deficits because they transpire more water than the stems can supply. University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers recently tested different concentrations of white and red kaolin particle films to determine the effects on water use in citrus trees. The rate and color of particle film used should be chosen based on the weather.
Higher concentrations of kaolin particle films led to a significant reduction in plant water use in citrus trees. By reducing water consumption, the use of kaolin particle films can also regulate the balance between water uptake through the stem and water loss through transpiration. However, while higher concentrations of kaolin particles significantly reduce water use, they also increase stomatal closure, which negatively affects photosynthesis. In the UF/IFAS study, the lowest concentration of white and red kaolin had higher stomatal conductance, which means that the stomata were more open for photosynthesis.
The stomatal response depended on the temperatures the plants were experiencing, because of the demand for water. At lower concentrations, red-dyed kaolin particle films were more effective than white films in reducing water use, even when both films provided the same level of shading. The difference between the white and red kaolin particles is mainly due to the reflectance property of the white kaolin, which allows more light into the canopy, increasing water loss through transpiration. At high temperatures, higher rates of white-colored Surround or using a red dye-kaolin mixture increased stomatal conductance over the course of the day. However, at low temperatures, higher rates or the use of red-dyed kaolin reduced stomatal conductance.
During the summer, beginning when temperatures rise with low rainfall, red kaolin particle film, which reduces water use more and has a greater impact on psyllid population, should be employed at a concentration of 17 pounds of Surround per acre. In spring and fall, white particle films are recommended at a concentration of 12 pounds of Surround per acre. It may be best to not apply particle films in the winter.
Sharpton Toussaint is a graduate research assistant, and Christopher Vincent is an assistant professor, both at UF/IFAS.
Share this Post