Plant reproductive success declines with age, but the mechanisms underlying this phenomenon remain poorly understood. This is an important knowledge gap because reduced fertility in ageing plants can limit seed production and quality, with potential consequences for agriculture and food security. While previous studies have mainly focused on maternal age, the relative contributions of maternal and paternal ageing and the molecular mechanisms driving reproductive decline remain unclear. The AgriFert project will investigate how plant age affects fertility, seed quality and the fitness of the next generation. I hypothesize that age-related fertility decline is driven primarily by changes in reproductive tissues, including altered gamete production, gene expression, small RNA regulation and phytohormonal signalling. I will test this hypothesis through four complementary objectives: (1) disentangle the contributions of male and female gametes to age-dependent fertility decline; (2) identify molecular and regulatory mechanisms underlying reproductive ageing; (3) determine the role of cytokinins in age-dependent fertility loss; and (4) establish how parental age affects seed development, seed quality and progeny fitness. The project will combine phenotypic analyses, reciprocal crosses, microscopy, transcriptomics, small RNA sequencing, genetic approaches and hormone manipulation. A comparative analysis of the annual self-pollinator Arabidopsis thaliana and the perennial outcrosser Arabidopsis lyrata will further determine how life cycle and mating system shape reproductive ageing. By integrating reproductive biology with molecular and hormonal analyses, AgriFert will establish a mechanistic framework for understanding fertility decline in ageing plants. The results will provide new insights into plant reproduction and senescence and may ultimately contribute to strategies for prolonging the high-fertility period and improving seed production and quality in sustainable agriculture.