Laboratory of Biology, State University of Mato Grosso do Sul, Coxim, MS, Brazil; Department of Plant Physiology and Biochemistry, Postgraduate Program in Plant Biodiversity and Environment, Institute of Botany, São Paulo, SP, Brazil.
Laboratory of Biology, State University of Mato Grosso do Sul, Coxim, MS, Brazil.
Plant Physiol Biochem. 2019 Feb;135:206-214. doi: 10.1016/j.plaphy.2018.12.002. Epub 2018 Dec 7.
Invasive grasses inhibit the growth of other plant species, and water deficit is one of the major competition problems for native vegetation. We evaluated whether the presence of Brachiaria brizantha cv. Piatã has a negative influence on the competition for water and nutrients between Anadenanthera macrocarpa and Anadenanthera colubrina (Angico species). The interspecific competition was evaluated using a randomized experimental design with the following treatments: 1) free competition (FC), in which the native species were cultivated without the grass presence and 2) under competition (UC), in which the native species grew together with the invasive grass for 120 days. We analysed the water relationships in the two species, the effect of water limitation on the antioxidant stress, the nutritional content of shoots and roots, the relative competition intensity (RCI) and growth. The presence of Piatã grass reduced the soil moisture causing a decrease of 21.9% and 29.5% in the relative water content (RWC) of leaves for A. macrocarpa and A. colubrina, respectively. For the two Angico species, the quantum efficiency of Photosystem II (ΦPSII) decreased with reduction of RWC leaf, resulting in the HO increase (57.5% at day 30 for A. colubrina and 38.8% at day 120 for A. macrocarpa). The oxidative stress was evidenced by the increase in the superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities in leaves and roots of both young native trees. In the UC treatment, reductions in water uptake also led to a decrease in root absorption of N, P, K, a Mg and low transport of these nutrients to the leaves of both Angico species. A. macrocarpa and A. colubrina showed less growth caused by limitation of water uptake, but the joint activity of the physiological and biochemical adjustments provided competitive ability.
入侵草种会抑制其他植物物种的生长，而水分亏缺是本地植被面临的主要竞争问题之一。我们评估了 Brachiaria brizantha cv. Piatã 的存在是否会对 Anadenanthera macrocarpa 和 Anadenanthera colubrina（金合欢物种）的水分和养分竞争产生负面影响。使用随机实验设计评估种间竞争，处理如下：1）自由竞争（FC），即在没有草存在的情况下种植本地物种，2）竞争（UC），即在入侵草存在的情况下，本地物种共同生长 120 天。我们分析了两种物种的水分关系、水分限制对抗氧化应激的影响、地上部和地下部的营养含量、相对竞争强度（RCI）和生长情况。Piatã 草的存在降低了土壤水分，导致 A. macrocarpa 和 A. colubrina 的叶片相对含水量（RWC）分别下降了 21.9%和 29.5%。对于两种金合欢物种，叶片的光系统 II（PSII）量子效率（ΦPSII）随着 RWC 叶片的降低而降低，导致 HO 增加（A. colubrina 在第 30 天增加 57.5%，A. macrocarpa 在第 120 天增加 38.8%）。叶片和根系中超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）活性的增加证明了氧化应激的存在。在 UC 处理中，水分吸收的减少也导致两种本地幼树根系对 N、P、K、a Mg 的吸收减少，以及这些养分向叶片的运输减少。A. macrocarpa 和 A. colubrina 的生长受到水分吸收限制的影响，但生理和生化调节的联合作用提供了竞争能力。
