Seed conditioning of Brachiaria decumbens with zinc oxide and Ecklonia maxima for mitigating drought stress.

• Grant number: 25/14623-7
• Support Opportunities: Scholarships in Brazil - Master
• Start date: January 01, 2026
• End date: February 28, 2027
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Flávio Henrique Silveira Rabêlo
• Grantee: Mauro Ernesto Issufo
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The progression of climate change and the intensification of dry periods may compromise the germination and establishment of tropical forage crops, especially Brachiaria decumbens, the basis of pasture-based livestock farming in Brazil. Although adapted to the tropical climate, its seeds are highly sensitive to water stress due to drought, which hinders the development of productive and sustainable pastures. As an alternative, this project proposes seed priming with zinc oxide (ZnO) and Ecklonia maxima algae extract, alone or in combination, as a strategy to promote greater drought tolerance. The study will be conducted in two phases: the first, in the laboratory, will involve the germination of seeds under different levels of water stress induced by PEG 6000 (0.0; -0.3 and -0.6 MPa), with the following treatments: without conditioning, hydropriming (water), ZnO (700 mg kg¿¹ of seeds), Ecklonia maxima (0.5% v/v) and the combination ZnO + E. maxima; with evaluation of the germination percentage, speed and average germination time. The second phase, in a greenhouse, will include morphophysiological and biochemical analyses (activity of enzymes that make up the antioxidant system), relative water content, chlorophyll content, nutrient concentration, and oxidative stress indicators (hydrogen peroxide - H¿O¿ and lipid peroxidation - MDA). The aim is to understand the adaptive responses induced by the same treatments applied under two water conditions: 70% of field capacity (control) and 40% of field capacity (moderate stress). Treated seeds are expected to exhibit greater uniformity of emergence, vigor, and resilience to water deficits, providing scientific support for sustainable technologies in the formation of tropical pastures in the face of climate instability. (AU)