Genetic variation in seed dormancy, soil tolerance, and pH response jointly shape early establishment in Lupinus species

The ability of seeds to overcome dormancy and establish seedlings under variable conditions determines crop establishment success in agroecosystems. Genetic diversity in dormancy-related traits and their interaction with soil and pH conditions define the ecological and agronomic limits of early establishment in Lupinus. We evaluated 50 accessions from three species (L. angustifolius, L. luteus, and L. albus) to quantify how variation in seed-coat impermeability interacts with edaphic constraints. Using three complementary experiments-standardized scarification assays, multi-soil trials, and pH-gradient tests-we assessed physical dormancy (PD), germination dynamics, and early seedling establishment performance. In L. angustifolius, mechanical scarification increased germination by up to 85%, and under non-scarified conditions, DDS₅₀ (days to 50% germination) varied widely among accessions (from < 10 to > 200 days). However, low-PD accessions did not consistently achieve high establishment success, indicating that dormancy traits alone do not predict establishment. Generalized linear mixed models revealed strong species × soil and species × pH interactions for emergence and establishment success (P < 0.001), with establishment rates varying from < 20% to > 80% among accessions and environments. Multivariate analyses (PCA and clustering) differentiated accessions with broad versus narrow establishment responses. An integrative, phenotype-based selection index combining establishment success, seedling length, and performance stability under pH gradients identified L. albus and L. luteus accessions with consistent performance across soils, and a subset of L. angustifolius accessions performing well under alkaline conditions. Our findings demonstrate that seed dormancy, soil compatibility, and pH tolerance act as complementary filters, and that integrative phenotyping frameworks can guide genetic selection of resilient Lupinus cover crops for Mediterranean orchards and other perennial systems under climate variability.