Germination under stress simulation and image analysis as tools for water deficit phenotyping of maize

Abstract

Faster phenotyping tools are crucial for field progeny selection. We conducted research comparing two water deficit simulation methods on contrasting cultivars for water deficit tolerance. In a first step, we conducted two experiments: one for seed germination in sand at 10% and 70% water retention capacity, being analyzed seedling emergence and growth; other for seed germination in stress simulation by moistening the germination paper with PEG solution at -0.6 MPa, being analyzed seed germination. These experiments were used to distinguish characteristics of two maize lineages with different response to drought, being 57 - sensitive and 91 - tolerant. After that, we produced hybrid progenies from these lines at generations F1, F2, and F2:3 and applied the stress simulation by moistening the germination paper with -0.6 MPa of PEG solution. The seedling size was analyzed trough image analysis by the GroundEye® system. We could distinguish both lines and its hybrids through the stress simulation and image analysis. The results indicate that maize cultivars can be phenotyped for water deficit tolerance either 5 days postsowing through stress simulation or via image analysis of root length from seedlings germinated under -0.6 MPa. This method provides faster, more accurate, and more cost-effective methods for assessing water deficit tolerance in maize cultivars.