Germination and initial development of Brachiaria brizantha and Brachiaria decumbens on exposure to cadmium, lead and copper

Abstract

-The objective was to evaluate the germination and initial development of three cultivars of Brachiaria brizantha and Brachiaria decumbens in the presence of trace elements of Cd, Pb and Cu and quantify the Cd and Cu contents in plant tissue of these species. First, seed germination occurred in towel paper containing cadmium, lead, copper and the control. We calculated the percentage of germination, germination speed index, vigor index and seedling length. Later, the seeds were germinated in soil pots contaminated with Cd and Cu, where the Soil-Plant Analysis Development index (SPAD index) was evaluated, as well as dry matter of shoot and root, and the Cd and Cu metal content in plant tissue was quantified. B. decumbens showed sensitivity to the elements studied, with decreases in all parameters. Cu was the element that caused more toxic effects on germination and early seedling development of the species studied. In contaminated soil, the species studied showed no differences in dry matter production of shoots, but the exposure to Cd and Cu caused reductions in SPAD index in all species. The highest Cd and Cu contents were found in the roots.

Cadmium toxicity on seed germination and initial growth of chia

“…The results of this study corroborate Al-Qurainy (2010), who verified that in Eruca sativa root length decreased 28% and stem length decreased 44% for 50 mg L-1 of Cd. Also, Borges et al (2016) observed a reduction in root length of 2.5 and 1.0 cm in Brachiaria brizantha and B. decumbens when exposed to 180 mg L-1 of this metal. Similarly, Grigoraş and Stratu (2015) concluded that the Cd concentrations used (1.10; 1.6 and 2 mg L-1) did not affect seed germination, but negatively influenced seedling growth (especially the lengthening of the root) of Dianthus barbatus L. and D. chinensis L. According to these authors, the effect of the seedling growth delay can be attributed to metabolic and physiological disturbances caused by the Cd concentrations used in the treatments.…”

“…The main symptoms of toxicity are the following: inhibition of seed germination; disturbance of plant metabolic activities; reduction in the root system and stem; changes in the structure of chloroplasts; inhibition of photosynthesis; reduction of plant biomass; lipid peroxidation; decrease in respiration rate and growth; inhibition of the action of enzymes; reduction in cell division; and interference in cellular membrane permeability, which reduces the ability to absorb and transport water and essential elements (e.g., Ca, Mg and K) inside the plant, reducing tolerance to stress (Kabata-Pendias, 2010;Rahoui, Chaoui, & El Ferjani, 2010;Gill, Hasanuzzaman, Nahar, Macovei, & Tuteja, 2013;Chen et al, 2014). Studies of plant development under different Cd contamination levels have been conducted with the common bean (Santos, Fagan, Teixeira, Soares, Reis, & Corrêia, 2013), Jatropha curcas (Chaves & Souza, 2014), wheat (Ahmad, Akhtar, Zahir, & Jamil, 2012;Guilherme, Oliveira, & Silva, 2015), leaf mustard -Brassica juncea (Augusto et al, 2014;Alfiya & Dheera, 2015), crambe (Hu et al, 2015), Brachiaria brizantha and B. decumbens (Borges, D'avila, Campos, Coelho, Miquelluti, & Galvan, 2016), wheat and beans (El Rasafi, Nouri, Bouda, & Haddioui, 2016), chickpeas (Ahmad, Abdel-Latef, Abd-Allah, Hashem, Sarwat, Anjum, & Gucel, 2016), and basil -Ocimum basilicum - (Gharebaghi, Haghighi, & Arouiee, 2017), among others. However, no studies were found that evaluated the toxic effects of Cd on the seed germination of chia.…”

Germinação de espécies forrageiras na presença de cádmio, cobre e chumbo

“…Para as variáveis IVG e RA ocorreu apenas efeito de dose de Cu, sendo que, a presença de Cu resultou em redução do IVG em dez vezes e inibiu a emissão de raiz (Tabela 3). As espécies de gramíneas estudadas por BORGES et al (2016) não apresentaram inibição de emissão de raiz, o que sugere, que as espécies avaliadas no presente estudo são menos tolerantes ao Cu.…”

“…) (BORGES et al 2016). O efeito do Pb na germinação e desenvolvimento das plântulas das espécies aveia preta (Avena stringosa) e nabo forrageiro (Raphanus sativus) foi avaliado por BORGES et al (2019).…”

“…destaca-se pela quantidade de matéria seca produzida, pelo fácil cultivo e pela sua adaptação sob diferentes solos, entretanto, poucos são os estudos com este gênero na presença da contaminação por elementos-traço. Gramíneas têm um melhor estabelecimento em áreas contaminadas com elementos-traço, com facilidade no desenvolvimento, rápido crescimento, ajudando na ciclagem de nutrientes, aumentando o teor de matéria orgânica e melhorando a cobertura do solo (BORGES et al 2016). Para Panicum maximum Jacq., as cultivares disponíveis comercialmente são basicamente adaptadas a solos profundos, bem drenados e de boa fertilidade (CORREA & SANTOS 2003).…”