Crescimento e comportamento fisiológico de procedências de pinhão-manso (Jatropha curcas L.) em diferentes níveis de alumínio

Abstract

The toxicity of aluminum (Al) is considered one of the main factors limiting agricultural productivity in various regions of the planet. Considering the lack of information on the tolerance of physic nut to aluminum, the present study aimed to evaluate the growth and physiological behavior of provenances of physic nut (Jatropha curcas L.) at different levels of aluminum. The experiment was conducted in a greenhouse in the Faculty of Agrarian Sciences (FCA) University Federal of Grande Dourados (UFGD) during the period January to April 2012. The experimental unit consisted of vase with a capacity of 5.0 dm3 of soil, which was used as substrate soil collected at a depth of 80 to 100 cm. The treatments were arranged in a completely randomized (DIC), and for evaluations of growth, gas exchange and chlorophyll fluorescence a delineation of treatments were used in split-plot design in which the treatments in plot were four levels of aluminum (0.0, 8.2, 16.5 and 24.0 mmol dm-3), the subplots consisted of four provenances of physic nut seeds (P1 = Dourados-MS; P2 = Montes Claros-MG; P3 = Alta Floresta - MT; P4 = Petrolina-PE), and the subsubplots consisted in the 4 times (25, 50, 75 and 100 days after emergence). As for evaluations of emergency, OJIP curve of chlorophyll fluorescence a and enzyme activity treatments were arranged in a 4 x 4 factorial, referring to the four levels of aluminum in the soil and the four provenances of physic nut seeds. The different levels of aluminum were obtained from the initial soil amendment, which had an aluminum concentration of 24.0 mmol dm-3. The aluminum levels evaluated had no significant effect on seedling emergence of independent provenances. The increased levels of aluminum in the soil reduced the growth and dry matter accumulation of provenances P1-Dourados, P2-Montes Claros and P3-Alta Floresta. The gas exchange were negatively affected by aluminum and chlorophyll fluorescence a indicate the detrimental effect of aluminum, and through the curve OJIP can verify reduction photochemical efficiency. The activity of enzymes catalase, peroxidase and superoxide dismutase were higher in the presence of aluminum for the provenances P3-Alta Floresta and P4-Petrolina, in which this result added to the responses to growth and other physiological characteristics indicate less sensitive of these genotypes conditions of aluminum stress.