Uso de radiação UV-C em plantas, ácaro-rajado e filmes plásticos agrícolas empregados na cultura do morangueiro

Abstract

Strawberry culture is very vulnerable to pest and disease attacks. One of these pests is the two-spotted spider mite (Tetranychus urticae), which is able to cause losses of up to 80% of production, and that demands many applications of defensive chemicals to be controlled, which aren’t very effective. A technology that’s being developed to control this pest, and many other diseases of strawberry and other cultures, is UV-C radiation. UV-C radiation is a form of physical control capable of causing death to invertebrates, fungi and bacteria present in the surface of leaves, while also enhancing the concentration of compounds related to defence against diseases and herbivory in plants. Despite this, it’s use can cause physiological damage to the plant and physical damage to the production structures if it’s dose is too high, which makes research necessary to know which doses are tolerated by the plant, and if these doses are efficient to control the two-spotted spider mite. In view of this, three experiments were done with the objective of establishing the safety and efficiency of this technology. The first experiment sought to evaluate the effect of different doses of accumulated radiation (1,925 kJ m-2, 1100 kJ m-2, 825 kJ m-2 and 0 kJ m-2) over the chlorophyll (SPAD) content of leaves. The second experiment sought to test the lethality of UV-C radiation over T. urticae in different doses of radiation (0kJ m-2, 0.165 kJ m-2, 0.275 kJ m-2, 0.55 kJ m-2, 1.1 kJ m-2 e 2.2 kJ m-2). The third experiment sought to evaluate the potential degradative of different doses of UV-C light in different doses of radiation (0kJ m-2, 198 kJ m-2, 594 kJ m-2 and 990 kJ m-2) over a plastic used as mulching in strawberry production. The results of the experiments showed no change in the concentration of chlorophyll in the leaves of strawberry, which establishes that there has been no damage to the photosyntetic system of the plants. The second experiment showed that exposures of 10, 20 and 40 seconds to UV-C light reduced the population of mites by 78,06%. The experiment with the degradabilty of plastics didn’t yield evidence that a degradative proccess happened due to UV-C treatments.