Atrazine toxicity to Handroanthus heptaphyllus, a nontarget species from a Brazilian biome threatened by agriculture

Abstract

The economic basis of the Brazilian midwest is agriculture, concentrating most of the grain production in the country. With the purpose of increasing yield, farmers have intensified land use and the use of atrazine among other pesticides, which can supposedly compromise human health and photosynthetic metabolism of plant species from Cerrado, such as Handroanthus heptaphyllus. The aim of this study was to determine experimentally the sensitivity level of H. heptaphyllus to atrazine, by measuring gas exchange, chlorophyll a fluorescence, chloroplastidic pigments, and membrane permeability. The experiment was conducted in a factorial scheme. Nine‐month‐old H. heptaphyllus plants were treated with six realistic doses of atrazine: 0, 25, 50, 100, 200, and 400 g a.i. ha–1 (corresponding to 10, 20, 40, 80, and 100% of the commercial dose recommended for corn crops, respectively), with five replications. Evaluations were performed at 12, 36, 84, 180, and 276 h after treatment application. Photosynthesis, the effective quantum yield of photosystem II, and electron transport rate were gradually reduced by the action of atrazine. On the other hand, the nonphotochemical quenching increased gradually, which indicates that this mechanism was not sufficient to avoid oxidative stress and cellular damage in H. heptaphyllus treated plants. Based on these results, we concluded that the action of the herbicide in the photosynthetic reduction occurs by the electron transport rate limitation. Therefore, H. heptaphyllus trees are at risk in Cerrado areas next to agricultural lands.

Phytotoxicity of atrazine combined with cadmium on photosynthetic apparatus of the emergent plant species Iris pseudacorus

“…In this study, the gradual increase in DI 0 /RC with increasing ATZ concentration suggested that partial excitation energy was dissipated in nonphotochemical processes, especially achieving signi cant differences at higher levels of ATZ (≥ 1.0 mg•L − 1 ). The signi cant increase in the nonphotochemical quenching was also observed by Silva et al (2021) in determining the sensitivity level of Handroanthus heptaphyllus to ATZ. Though this increase diminished the fraction of energy delivered to PS II centers, it played an important role in the mitigation against photodamage, which re ected the tolerance of I. pseudacorus to ATZ by activating the photoprotective responses (Cazzaniga et al 2013).…”

“…These results suggested that this plant species exhibited relatively high tolerance to ATZ stress at this level through enhancing the electron supply from P 680 to Q A and energetic connectivity. To minimize damage to the photosynthetic apparatus, excess energy can be dissipated as nonphotochemical processes, including thermal dissipation (Silva et al 2021). In this study, the gradual increase in DI 0 /RC with increasing ATZ concentration suggested that partial excitation energy was dissipated in nonphotochemical processes, especially achieving signi cant differences at higher levels of ATZ (≥ 1.0 mg•L − 1 ).…”

Morpho-physiological and biochemical mechanisms of copper tolerance in Handroanthus heptaphyllus

“…The species has significant ecological and economic value, making it useful for afforestation and urban landscaping projects (Berghetti et al, 2021). They are also commonly used in reforestation programs and to restore degraded areas (Silva et al, 2021). The timber from this species is used in construction due to its high density, strength, and malleability (Parcianello et al, 2021).…”