Potencial fitorremediador de tagetes (Tagetes patula L.) cultivado em solo contaminado por cobre

Abstract

In the cultivation of flowers and ornamental plants in pots, the leaf quality is one of the most valued commercial parameters, being the soil or substrate conditions fundamental to the success of this cultivation. Thus, the objective of this work was to evaluate the foliar development of tagetes (Tagetes patula L.) plants grown in different copper (Cu) contents and soil pH. The experiment took place in the greenhouse of the Department of Plant Science, in the year 2021, using an experimental design entirely randomized, with a 5x2 factorial design (five added levels of Cu in the soil: in the amounts of zero (without addition), 250, 500 and 750 and 1,000 mg kg 1 of copper sulfate and two conditions of soil pH: pH 5.5 without the addition of lime (according to the report of the soil analysis) and pH 6.0 with the addition of lime PRNT 76%), with five repetitions. The soil used was collected from a viticultural area in the municipality of Santa Maria, RS, at a depth of 0-20 cm. The seeds used came from the cultivation in the experimental area of the Floriculture Sector, in the 2019/2020 harvest. The seedlings were transplanted 15 days after sowing (DAS) plastic pots, filled with the aforementioned soil, with a volume of 1.3 L, 14.5 cm in diameter, 12 cm in height, with a distribution of 10 pots m-2. The numbers, widths (L) and lengths (C) of leaves were evaluated at an interval of three between days 20 and 38 days after transplanting (DAT). The leaf area was calculated by the formula [AF: (C x L) x k], where the k assumes the value of 0.44, due to the leaf clippings. It was verified, at 38 DAT, that there was a positive interaction in the soil-plant-vase system, presenting harmonic development of the aerial part by the size of the vase. It was observed that at pH 5.5 the mean leaf areas (CV 4.49%) were 13.5; 35.6; 29.3; 14.8 and 12.3 cm2 for 0, 250, 500 and 750 and 1,000 mg kg-1 of Cu, respectively, with mean leaf numbers of 14; 31; 33; 20 and 20 (CV 5.10%) in the same sequence. At pH 6.0 the mean leaf areas (CV 60.7%) were 23.3; 40.5; 34.6; 21.5 and 29.0 cm² for 0, 250, 500 and 750 and 1,000 mg kg-1 Cu, respectively, with mean leaf numbers of 16; 30; 44; 37 and 35 (CV 4.79%) in this order. Among the soil pH conditions, the leaf areas developed more at pH 6.0, evidenced by the higher leaf numbers. Among the levels of Cu in the soil, it was observed that plants over 250 mg kg-1 of Cu obtained better leaf development for both conditions of pH, in relation to the other levels. The foliar development of pot-grown tagetes plants were affected by different Cu contents and soil pH