Parâmetros biométricos e índices fisiológicos de plantas de pinhão manso (Jatropha curcas l.) sob aplicação de herbicidas

Abstract

An alternative to changing the energy matrix is the use of renewable energy source, thereby producing biodiesel using oilseed plants has been gaining attention increasingly in the world. Among the crops that have an emphasis on the production of biofuel, there is the Jatropha culture. The jatropha plants are likely in its early stages the competition by weeds, so necessary mechanical or chemical control during the early stages of crop establishment. This study aims to evaluate the physiological indices of Jatropha plant (Jatropha curcas L.) submitted to different herbicide mode of action. The adopted design was a randomized block in a factorial design (9 x 5) + 1, with 9 herbicides, 5 evaluation periods and one witness. The seedlings were transplanted to plastic bags with two months of age, who received fertilization with NPK 5-25-15 formulation (40 g / plot). The treatments were studied Oxifluorfem (240 g.i.a.), Flumioxazina (25 g.i.a.), S-Metolacloro (1920 g.i.a.), Carfentrazona (32 g.i.a.), Tembotriona (100 g.i.a.), Bentazona (1200 g.i.a.), Metribuzin (480 g.i.a.), Flumioxazin + Oxifluorfem (25 + 240 g.i.a.) e Carfentrazone+ S-Metolacloro (32 + 1920 g.i.a.), 1 more witness with 5 repetitions. Treatments were applied on 20 June 2014, seven days after transplantation, using a backpack sprayer of accuracy, the pressurized CO2 and calibrated to apply spray volume of 150 L ha-1. They evaluated the visual symptoms of poisoning plants at 7, 14, 21, 28 and 35 days after treatment application. At 15, 30, 45, 60 and 75 days after application, the following variables: plant height (PH, cm), stem diameter (DC, in mm), number of leaves (NF) and root length (CR in cm), dry matter of the leaves (MSF), stem (MSC), root (MSR), total dry matter (MST), leaf area, specific leaf area, leaf area ratio, leaf weight ratio, TCA, RGR and NAR. Treatments with the oxifluorfem herbicides flumioxazin and flumioxazin + oxyfluorfem, were the main cause harmful effects on plants and influencing the total dry matter accumulation. The treatments with herbicides flumioxazin, s-metalacloro, were most likely reduced the absolute growth rate on the assessed periods.