Germination and initial development of old and modern soybean cultivars as a function of heat stress

• Grant number: 24/22906-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2025
• End date: September 30, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Renan Caldas Umburanas
• Grantee: Gustavo de Souza Pinto Pedroso
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Climate change and global warming represent a growing challenge for agriculture. Soybean cultivars present phenotypic differences that impact their transpiration capacity, such as root biomass volume and partitioning, as well as aerial part attributes such as canopy architecture, leaf shape, stomata density, among others. A little-studied point is the phenotypic plasticity in soybean development during the germination and emergence stages. To evaluate contrasting cultivars, one strategy is to select materials from different release periods. The objective of this study is to evaluate the physiological and biochemical responses of old and modern soybean cultivars subjected to different thermal conditions during the germination and emergence phase. The specific objectives are to evaluate a stress indicator, proline level, under different thermal conditions. A completely randomized design in a 4×4 factorial scheme will be adopted with four soybean cultivars (two old: Cd 206 and Paraná; two modern: Brasmax Potência Brasmax Desafio), three temperatures (20°C, 28°C and 36°C) and 100 replicates. The evaluations include the emergence percentage, emergence speed index, average emergence time, shoot length and stem diameter. Fifteen days after emergence, a destructive evaluation will be performed to assess the main root length, average diameter, volume, altitude, projected area, root dry mass and shoot dry mass. The proline content will be quantified through the biomass of leaves and petioles. The results obtained will contribute to a better understanding of phenotypic plasticity in a contrasting group of cultivars. This knowledge can contribute to the development of future cultivars in the search for greater resilience to heat stress.