Influence of Climate Change on Flowering Time

Global warming affects various environmental factors, including temperature, precipitation, drought, and flooding. Temperature rise is mainly due to increased levels of carbon dioxide (CO₂), which was increased by approximately 50% since the industrialization period. Here, we review the effect of global climate changes on the alteration of flowering time. High temperature during vernalization delays flowering mainly due to increased expression of FLOWERING LOCUS C and TaVERNALIZATION 2 encoding floral repressors in Arabidopsis and winter wheat, respectively. Increased ambient temperature promotes flowering in many plant species, especially in spring-flowering plants. In Arabidopsis, higher temperature induces SHORT VEGETATIVE PHASE–FLOWERING LOCUS M (FLM)-δ complex that promotes FLOWERING LOCUS T (FT) expression. Moreover, high temperatures suppress a floral repressor FLM and disturb the stability of the evening complex that is an inhibitor of PHYTOCHROME INTERACTING FACTOR 4, which induces FT expression. Drought induces or delays flowering depending on plant species, growing season, and developmental stage. In Arabidopsis, drought induces flowering by promoting the GIGANTEA-CONSTANS (CO) pathway, whereas the stress delays flowering under short-day conditions via ABSCISIC ACID-INSENSITIVE 1. Plants also alter flowering time to avoid wet conditions, including flooding and precipitation. Increased CO₂ concentration accelerates flowering, probably by increasing the rate of photosynthesis. We also reviewed the effect of climate change on pollination.