Alessandra Ferreira Belo

Fitorremediação de solo adubado com composto orgânico e contaminado com trifloxysulfuron- sodium

Objetivou- se neste trabalho avaliar a capacidade remediadora das especies vegetais feijao- de- porco (Canavalia ensiformis) e mucuna- preta (Stizolobium aterrimum), em solo adubado com composto orgânico e contaminado com o herbicida trifloxysulfuron- sodium. Na primeira etapa, avaliou- se o crescimento de C. ensiformis e S. aterrimum nos diferentes substratos, contaminados ou nao com herbicida. Os tratamentos foram compostos pela combinacao entre duas doses do herbicida trifloxysulfuron- sodium (0,0 e 7,5 g ha- 1) e cinco teores de composto orgânico: 0, 25, 50, 100 e 200 m3 ha- 1 (equivalentes a 0, 1,25, 2,5, 5 e 10% do volume de solo em cada vaso, respectivamente), dispostos em esquema fatorial 2 x 5, sob delineamento inteiramente casualizado, com tres repeticoes, para cada especie remediadora. Um dia apos a aplicacao do herbicida a superficie do solo, procedeu- se a semeadura das especies remediadoras, deixando- se como testemunha vasos sem planta. Na colheita, aos 60 dias apos a emergencia, avaliou- se a altura e a massa seca da parte aerea (MSPA) dessas especies. Todo o material colhido foi triturado e incorporado ao solo dos seus respectivos vasos. Na segunda etapa, avaliou- se a capacidade remediadora de C. ensiformis e S. aterrimum. Os tratamentos foram compostos pela combinacao entre cinco teores de composto orgânico e cinco tipos de cultivo previo: cultivo de C. ensiformis e S. aterrimum na presenca e ausencia do herbicida trifloxysulfuron- sodium e um tratamento sem cultivo previo e com aplicacao de trifloxysulfuron- sodium, dispostos em esquema fatorial 5 x 5, sob delineamento inteiramente casualizado, com tres repeticoes. Amostras de 100 g de solo foram retiradas dos vasos (6 L) usados na primeira etapa e colocadas em vasos de 100 cm3. Em seguida, cultivou- se sorgo (Sorghum bicolor) para indicacao de residuo do herbicida no solo. Essas plantas foram colhidas 20 dias depois, epoca em que se avaliaram a altura, a MSPA e o grau de intoxicacao delas pelo herbicida. No solo com trifloxysulfuron- sodium e sem cultivo previo das especies remediadoras, as plantas de sorgo tiveram seu crescimento reduzido, mesmo com a adicao de composto orgânico. O cultivo previo de C. ensiformis e S. aterrimum proporcionou crescimento normal as plantas de sorgo, confirmando a capacidade remediadora dessas especies. A adicao de composto orgânico nao influenciou a capacidade remediadora das especies.

Potencial de espécies vegetais na remediação de solo contaminado com sulfentrazone

The aim of this work was to evaluate the efficiency of plant species in the remediation of a red-yellow Hapludalf contaminated with sulfentrazone. The work was conducted at two stages. At the first, the growth of Helianthus annus, Canavalia ensiformis, Dolichos lab lab and Arachis hypogaea was evaluated in soil contaminated with sulfentrazone. At the second stage, a species (sorghum) indicator of residues of this herbicide was sown in the same soil. At the first stage, pots containing 6.0 kg of substrate were used. After the pots were irrigated, the herbicide was applied on the soil surface. One day after the application, the vegetal species were sown. These species were collected 100 days later and stove-dried for determination of shoot dry matter accumulation. At the second stage, soil samples of 3.0 kg were collected from each pot where the species indicator of sulfentrazone residues was cultivated. At 20 and 50 days after emergence, the intoxication of the sorghum plants was visually determined and the shoot dry matter of these plants was determined 50 days after emergence and 50 days after the first cut. The production of shoot dry matter of H. annus, C. ensiformis, D. lab lab and A. hypogaea was not affected, indicating that all species were tolerant to sulfentrazone. However, H. annus showed greater capacity for remediation of soil contaminated with this herbicide.

Efeito da umidade do solo sobre a capacidade de Canavalia ensiformis e Stizolobium aterrimum em remediar solos contaminados com herbicidas

This paper aimed to evaluate the effect of soil humidity on Canavalia ensiformis and Stizolobium aterrimum capacity of remediating soil contaminated with tebuthiuron and trifloxysulfuron-sodium. The experiment was divided into two stages. In the first stage, soil at different levels of humidity were used, contaminated or not with herbicide, to evaluate C. ensiformis and S. aterrimum growth. Treatments consisted of a combination of tebuthiuron, trifloxysulfuron-sodium and herbicide absence, associated to four levels of soil water content (0.287, 0.358, 0.431 and 0.575 kg kg-1), arranged in a 3 x 4 factorial scheme, in a completely randomized design, with three replicates for each species. Trifloxysulfuron-sodium or tebuthiuron were applied on soil surface after preparing the substrate and filling the pots, and the species were sowed one day after that. At this stage, pots with same humidity level and under the same conditions, but without remediating plants, were used as control. After 60 days, plants were harvested to evaluate height and dry matter of ground tissue. All material was ground and incorporated into soil of their respective pots. At the second stage, the remediating capacity of C. ensiformis and S. aterrimum was evaluated. Treatments consisted of five humidity levels and five types of prior cultivation, arranged in a 4 x 5 factorial scheme, in a completely randomized design, with three replicates.Samples of 0.5 kg of soil were taken out from the pots previously used and placed in 0.5 L pots, where sorghum (Sorghum bicolor) was cultivated to trifloxysulfuron-sodium and soybean (Glycine max) to tebuthiuron. After 20 sowing days, plants were harvested to evaluate height, ground tissue dry matter and their intoxication level. C. ensiformis did not survive up to 60 days after sowing in tebuthiuron-contaminated soil, at any humidity level, and S. aterrimum survived when cultivated in soil between 0.287 and 0.358 kg kg-1 humidity. S. aterrimum was more efficient than C. ensiformis in soil decontamination with tebuthiuron. Sorghum and soybean grew better in soil contaminated with trifloxysulfuron-sodium or tebuthiuron, with prior cultivation, than in soil without prior cultivation. In general, remediation was not affected by humidity variation, with the effects on the development of remediating species being observed. C. ensiformis and S. aterrimum developed best in soil with humidity around 0.431 kg kg-1; however, at this level, tebuthiuron is more easily available for the soil solution.

Caracteres morfológicos de soja e braquiária consorciadas sob subdoses de fluazifop-p-butil

Pasture degradation is one of the most important problems, affecting directly the sustainability of animal production. As one of the alternatives for the recovery of the degraded pasture, the use of annual crops intercropped with forages has been proposed. However, for the viabilization of the intercropping it is necessary the adequate management of the forage to reduce the competition with the crop, searching both development. The objective of this work was to evaluate the effects of fluazifop-p-butil on the morphology of Brachiaria brizantha and soybean grown intercropped. The experiment was conducted at Coimbra-MG to evaluate six doses of fluazifop-p-butil (0, 18, 36, 54, 72 and 90g ha-1) applied at two times (21 and 28 days after soybean emergence - DAE). Additionally, two control treatments were included: soybean and B. brizantha in monocrop kept free of weeds. The time of application did not affect the efficacy of herbicide doses. The treatment without herbicide or at lower doses, affected negatively the leaf area index (LAI), leaves biomass, stem + petioles biomass and pods biomass of the soybean plants. The LAI, leaves biomass (LB), stems number, stem length and stems biomass (SB) of the B. brizantha, were affected by the doses and time of application. The application at 28 DAE caused more injury to the B. brizantha than at 21 DAE. It was verified that at 53 DAE the doses 0, 18 and 36g ha-1, applied at 21 DAE, and the doses 0 and 18g ha-1, applied at 28 DAE were similar to that of control (B. brizantha monocrop) for SB, LB and LAI. The dose of 36g ha-1 of fluazifop-p-butil benefited the B. brizantha compared to soybean. For the other hand the dose of 54g ha-1 of fluazifop-p-butil benefited the soybean compared to B. brizantha. For the conditions of this experiment, the ideal dose of fluazifop-p-butil for the intercropping establishment was 40g ha-1 of fluazifop-p-butil.

Efeito de herbicidas na atividade microbiana do solo

This work aimed to evaluate the effects of herbicides and doses on the microbial activity and inorganic phosphate solubilization potential of a soil cultivated with sugarcane. The treatments were composed by the herbicides ametryn, trifloxysulfuron-sodium, and ametryn + trifloxysulfuron-sodium at 0, 1, 2, 4, and 8 times the reference doses of 10, 0.112, and 7.315 + 0.185 mg dm3 of the active ingredient, respectively. After herbicide application, soil samples were incubated for 15 days and CO2 evolution (C-CO2) was evaluated every three days. At the end of incubation, microbial biomass carbon (MBC), metabolic quotient (qCO2), phosphate solubilization potential, and relative phosphate solubilization were evaluated for the treatments tested. C-CO2 evolution was affected by the herbicides and increasing application doses. Trifloxysulfuron-sodium caused a reduction in C-CO 2 evolution of 10.3% in comparison to the control. MBC and qCO2 were negatively affected by the herbicides ametryn and trifloxysulfuron-sodium + ametryn. Trifloxysulfuron-sodium reduced MBC when applied at decreasing doses; the reverse was observed for qCO2. Phosphate solubilization potential was reduced with the application of ametryn (47.20%) and trifloxysulfuron-sodium + ametryn (13.55%), while trifloxysulfuron-sodium applied singly stimulated this activity in the soil (25.48%). Similar behavior was observed for relative phosphate solubilization.

Colonização micorrízica e atividade de fosfatases ácidas na rizosfera de cultivares de cana-de-açúcar após aplicação de herbicidas

The objective of this work was to evaluate the impact of herbicides on the mycorrhizal colonization and rhizospheric acid phosphatase activity of sugarcane cultivars RB86-7515 and SP80-1816. The experiment was conducted in the field in a conventional tillage system, with 1.4 m spacing between plants and 18 buds m-1. A randomized block design was used following a 2 x 5 factorial, with four replications, in which the first factor corresponded to two sugarcane cultivars (RB867515 and SP80-1816) and the second to four herbicides (ametryn, 2,000 g ha-1; trifloxysulfuron-sodium, 22.5 g ha-1; ametryn + trifloxysulfuron-sodium, 1,463 + 37.5 g ha-1; sulfentrazone, 750 g ha-1). A control treatment without herbicide application was also included. Herbicide application was performed when sugarcane plants presented three to four leaves. The root system and the rhizospheric soil were collected for evaluation of mycorrhizal colonization and acid phosphatase activity at 7, 14, and 28 days after herbicide application (DHA). The herbicides tested did not affect acid phosphatase activity in the rhizosphere soil. RB897515 presented higher mycorrhizal colonization, 22.5 and 27.0%, compared to the control treatment at 7 and 14 DHA, respectively. After 7 DHA, the lowest mycorrhizal colonization, 11.5%, was recorded for cultivar RB867515 treated with trifloxysulfuron-sodium + ametryn. Trifloxysulfuron-sodium stimulated mycorrhizal colonization in the cultivar SP80-1816 at 14 DHA (46.3%). Both cultivars presented higher values of mycorrhizal colonization in the treatments with ametryn at 28 DHA. An increase in mycorrhizal colonization was generally observed along the cultivation period. Mycorrhizal colonization was distinct among the cultivars and herbicides tested.

Interação competitiva de Brachiaria brizantha e B. plantaginea sob doses reduzidas de fluazifop-p-butil, aplicadas em diferentes épocas

The objective of this work was to evaluate the competitive interaction between Brachiaria brizantha and B. plantaginea under reduced rates of fluazifop-p-butyl and different application timings. The experimental design was a randomized complete block, with four replications, arranged in a 6 x 3 factorial, consisting of six doses of fluazifop-p-butyl (7,5; 12,5; 18,75; 31,25; 43,75 and 62,5 g ha-1), applied in three times (14, 24 and 34 days after plant emergence - DAE) and a control without herbicide. The highest dose applied corresponded to 33% of the recommended dose for soybean (187,5 g ha-1). The evaluation of the treatments was accomplished 53 DAE. The plants were grouped into leaves and stems, and their dry biomass obtained. Leaf area, stem number and stem length of both species were determined. B. plantaginea was more susceptible to fluazifop-p-butyl than B. brizantha. It was observed that 25 g ha-1 of fluazifop-p-butyl, applied at 14 DAE allowed maximum B. brizantha dry biomass accumulation and satisfactory control of B. plantaginea. In this application timing the dose of 62.5 g ha-1 controlled both species. Regarding application timing, when treated with reduced doses not intended to achieve full species control, young plants of B. brizantha and B. Plantaginea presented better recovery ability.

Efficiency of a reduced herbicide rate for Brachiaria brizantha control in sugarcane

At different growth stages, weeds present different sensitivities to herbicides. Thus, the registered herbicide rate may be reduced under specific conditions, while maintaining satisfactory weed control. This study evaluated the efficiency of reduced rates of the formulated herbicide mixture Velpar K WG® (hexazinone + diuron) + Volcane® (MSMA) for Brachiaria brizantha control at different growth stages. Optimum weed control efficiency was obtained when applying 50% of the recommended rate in younger plants (plants with one to four leaves). In late applications, it is necessary to increase the herbicide rates and, under these conditions, 90% of the recommended rate for (diuron + hexazinone) + MSMA was estimated to be the most economical one.