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Avaliação do potencial dos extratos das macroalgas Codium tomentosum e Gracilaria gracilis como bioestimulantes
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Advisor(s)
Abstract(s)
As macroalgas são organismos fotossintéticos, muito diversificados. A espécie Gracilaria gracilis, bem como o Codium tomentosum, são comestíveis e apresentam compostos bioativos de elevado interesse, com diversas aplicações em diferentes áreas (alimentar, cosmética, entre outras).
Embora não sejam atualmente utilizadas de forma ampla na agricultura, as macroalgas são usadas há já muito anos como bioestimulantes de plantas. Recentemente, ressurgiu um novo interesse nas aplicações agrícolas das macroalgas, relacionado com a procura crescente de produtos que não prejudicam o ambiente e que tornam a produção vegetal mais rentável e sustentável.
As macroalgas apresentam na sua constituição, polissacarídeos e hormonas vegetais, (tais como as auxinas, as citocininas, o etileno, as giberelinas e o ácido abscísico), substâncias conhecidas por desempenharem um papel relevante no desenvolvimento e fisiologia das plantas. São também ricas em proteínas, fibras, vitaminas e minerais.
O principal objetivo deste trabalho foi a determinação do potencial bioestimulante de extratos de macroalgas, com especial ênfase no seu efeito sobre a germinação e o crescimento de plantas. Adicionalmente, foi testado o potencial aumento da resistência ao stress térmico e ao stress salino. O efeito bioestimulante foi testado em duas espécies agrícolas: alface (Lactuca sativa L.) e tomate (Solanum lycopersicum L.).
Foi possível concluir que, na maioria dos ensaios, as sementes expostas aos extratos de macroalgas das espécies testadas (Gracilaria gracilis ou Codium tomentosum) apresentam uma germinação mais acelerada do que o controlo, traduzida por uma percentagem de germinação mais elevada, em cada dia, apresentando, ainda, um desenvolvimento superior das radículas e dos hipocótilos N, bem como uma percentagem de humidade mais elevada. Foi, ainda, possível constatar que as sementes expostas aos extratos de Gracilaria gracilis e de Codium tomentosum apresentam uma maior resistência ao stress salino e ao stress térmico.
Macroalgae are widely known for being photosynthetic organisms. The species Gracilaria gracilis, as well as Codium tomentosum, are edible and present bioactive compounds of great interest, with various applications in different areas (food, cosmetics, among others). Although they are not currently widely used in agriculture, macroalgae have been used for many years as plant biostimulants. Recently, a new interest in the agricultural application of these macroalgae has emerged, related to the growing demand for products that do not harm the environment and that make plant production more profitable and sustainable. Macroalgae have in their constitution polysaccharides and plant hormones (such as auxins, cytokinin’s, ethylene, gibberellins, and abscisic acid), substances known to play a relevant role in plant development and physiology. They are also rich in protein, fiber, vitamins, and minerals. The main objective of this work was to determine the biostimulant potential of macroalgae extracts, with special emphasis on their effect on germination and plant growth. Additionally, the potential increase in resistance to heat and salt stress was tested. The biostimulant effect was tested on two agricultural species: lettuce (Lactuca sativa L.) and tomato (Solanum lycopersicum L.). It was possible to conclude that, in most trials, seeds exposed to macroalgae extracts of the species tested (Gracilaria gracilis or Codium tomentosum) show faster germination than the control, as well as a higher hypocotyl and root development and a higher moisture percentage. It was also possible to verify that the seeds exposed to extracts of Gracilaria gracilis or Codium tomentosum showed greater resistance to salt and heat stress.
Macroalgae are widely known for being photosynthetic organisms. The species Gracilaria gracilis, as well as Codium tomentosum, are edible and present bioactive compounds of great interest, with various applications in different areas (food, cosmetics, among others). Although they are not currently widely used in agriculture, macroalgae have been used for many years as plant biostimulants. Recently, a new interest in the agricultural application of these macroalgae has emerged, related to the growing demand for products that do not harm the environment and that make plant production more profitable and sustainable. Macroalgae have in their constitution polysaccharides and plant hormones (such as auxins, cytokinin’s, ethylene, gibberellins, and abscisic acid), substances known to play a relevant role in plant development and physiology. They are also rich in protein, fiber, vitamins, and minerals. The main objective of this work was to determine the biostimulant potential of macroalgae extracts, with special emphasis on their effect on germination and plant growth. Additionally, the potential increase in resistance to heat and salt stress was tested. The biostimulant effect was tested on two agricultural species: lettuce (Lactuca sativa L.) and tomato (Solanum lycopersicum L.). It was possible to conclude that, in most trials, seeds exposed to macroalgae extracts of the species tested (Gracilaria gracilis or Codium tomentosum) show faster germination than the control, as well as a higher hypocotyl and root development and a higher moisture percentage. It was also possible to verify that the seeds exposed to extracts of Gracilaria gracilis or Codium tomentosum showed greater resistance to salt and heat stress.
Description
Keywords
Macroalgas vermelhas Macroalgas verdes Gracilaria gracilis Codium tomentosum Bioestimulantes Germinação de sementes Ensaios de crescimento Ensaios de stress Red seaweed Green seaweed Biostimulants Seed Germination Growth tests Stress tests