Climate change impacts flowering, pollinator interactions, and seed yield in canola

Insect-mediated pollination is a crucial ecosystem service that significantly contributes to the fertilisation of crop plants. However, as extreme weather events become more frequent with climate change, environmental stressors such as heat waves and drought threaten this mutualistic interaction, posing risks to global food production. We examined how heat and water stress affect flowering phenology, traits (flower number and size, nectar volume, and concentration), pollinator visitation, and seed yield in three canola varieties. We found that plants in heat and drought stress conditions bloomed earlier, produced fewer flowers, and shortened their flowering period, making them less attractive to pollinators. Plants also produced smaller flowers with reduced volumes of highly concentrated nectar relative to those in ambient conditions. Reproductive output declined under water limitation, with drought‑stressed plants producing significantly fewer pods and seeds than well‑watered plants, while total seed weight was reduced under both heat and drought. We found that flower abundance positively influenced seed yield across treatments, whereas pollinator visitation was a key factor for seed yield under ambient conditions but not in hot/drought conditions. Our findings highlight the complex ways in which climate change affects plant phenology, floral rewards, and reproduction, potentially disrupting plant-pollinator interactions and threatening crop production.