Uncovering Stable Genetic Loci for Sustainable Pea (Pisum sativum L.) Production Through Genome-Wide Association Mapping

A comprehensive evaluation of phenotypic diversity, genetic structure, and marker–trait associations was conducted in a pea (Pisum sativum L.) collection of 184 accessions, using multi-environment field trials and genome-wide SNP data. Agronomic traits were assessed using best linear unbiased estimates, and statistical analyses included correlation, analysis of variance, heritability estimation, population structure, linkage disequilibrium, and genome-wide association study of 10,289 SNP markers. Phenological traits showed low variability, with flowering and maturity averaging 36.08 and 79.19 days (coefficient of variation of 6.17% and 3.79%, respectively), whereas yield-related traits varied more widely, with the number of pods per plant showing a coefficient of variation of 26.14%. Strong correlations were observed between plant height and height of the lowest pod attachment (r = 0.89, p < 0.001), while moderate positive correlations were found between flowering and maturity time (r = 0.43, p < 0.001) and between number of pods per plant and plant height (r = 0.44, p < 0.001); meanwhile, thousand seed weight exhibited significant negative correlation number of pods per plant (r = −0.42, p < 0.001). Heritability was highest for plant height (H2 = 0.925), height of the lowest pod attachment (H2 = 0.889), and thousand seed weight (H2 = 0.883), while yield showed lower heritability (H2 = 0.672) and strong environmental influence. Linkage disequilibrium decay was 1.78 Mb at r2 = 0.2. GWAS identified 163 quantitative trait loci, including 19 stable loci, with strong effects such as −19.27 cm for q.PH.5-1 and +24.62 g for q.TSW.4-2. Candidate genes associated with key biological processes were identified, thereby enhancing understanding of the genetic control of traits.