Evaluation of the effects of biostimulants on the Madeiran maize variety ‘Milho de Santana’ under drought conditions

• Autor(a) principal: Silva, Patrícia Raquel Abreu
• Data de Publicação: 2024
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.13/5574
• topic: Agriculture; Biostimulants; Chitosan nanoparticles; Drought; Microorganisms; Agricultura; Bioestimulantes; Microorganismos; Nanopartículas de quitosano; Seca; Applied Biochemistry; .; Faculdade de Ciências Exatas e da Engenharia; Domínio/Área Científica::Ciências Agrárias::Biotecnologia Agrária e Alimentar; Domínio/Área Científica::Ciências Naturais::Ciências Biológicas; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

Anthropogenic activities are responsible for the emission of greenhouse gases into the atmosphere, which leads to an increase in their concentration and, therefore, an increase in temperature. Drought is one of the stressors that most disturb crop production. Biostimulants are eco-friendly substances and can be used to enhance stress tolerance. However, weekly treatments are needed to make them effective, which is disadvantageous for larger farms. One solution to overcome this problem is to use nanoencapsulation techniques to prevent degradation or provide controlled release of biostimulants. In this study, the ionotropic gelation technique was used to produce chitosan nanoparticles, which is fast, relatively cheap, and does not require expensive reagents and equipment, or organic solvents. In this study, L-pyroglutamic acid (LPGA) was used as the main biostimulant. The Madeiran maize variety called ‘Milho de Santana’ was subjected to drought. Well-watered (WW) plants with 100 % irrigation were compared to water-deficit (WD) plants under a 50 % irrigation. The following experimental variants were assessed: control (C), empty particle of chitosan (EP), entrapped biostimulant in chitosan particles (EBs), and free biostimulant (Bs). Hoagland’s nutrient solution and the experimental variants were directly applied to the soil. Five assays were performed: the first three to establish the experimental design and the last two to assess biostimulant action. Parameters such as soil water content, size of chitosan particles, peat microbe analysis, whole-plant biomass dry weight, root, aerial-part and whole-plant lengths, root stress index (SI), proline (Pro), total soluble sugars (TSS) in roots and aerial parts (stems and leaves), and correlations between these parameters were analysed. No significant differences (p < 0.05) were detected for most parameters, except for TSS in the roots and aerial parts. Sampling size, maize variability, difficulties in stress and irrigation reproducibility, among other reasons, may explain the obtained results.