Processed-kaolin particle film on papaya leaves: a study related to gas exchange, leaf temperature and light distribution in canopy.

摘要

Environmental factors such as light, temperature, water and mineral nutrients can affect physiological processes in papaya plants. A deeper understanding about the effects of such environmental factors over the physiological processes is of extreme importance, since it will allow us to trace strategies for managing them and will optimize the effects of these factors in relation to the growth and development of Carica papaya L. Processed-kaolin particle films are used in horticultural crops to repel insects, suppress disease incidence and reduce heat stress and solar injury. Effects of foliar sprays of a processed-kaolin particle film (Surround WP) on gas exchange, leaf temperature of sun-exposed leaves and light distribution/reflection in canopy on field-grown papaya plants (Carica papaya L.) were studied on September 25 and 26, 2003 in Linhares/ES/Brazil. Papaya plants were sprayed with two applications, using ~13 L (10% processed-kaolin). The 10% foliar processed-kaolin particle film application did not affect net CO₂ assimilation rates, stomatal conductance and transpiration in papaya leaves; although the light reflection was higher and the temperature on the leaves was lower during the period from 12 pm and 2 pm in the plants that received the particles on the leaves.