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We examined the combined effects of temperature, carbon dioxide (CO2) and watering regime during seed maturation on subsequent germinability and total phenolics of Arabidopsis thaliana [wild-type (WT) and abi1-1 mutant] seeds. Mature seeds were collected from plants that were grown under lower (22/18 degrees C, 16 h light and 8 h dark) or higher (28/24 degrees C, 16 h light and 8 h dark) temperatures, at ambient (400 mu mol mol(-1)) or elevated (700 mu mol mol(-1)) CO2 concentration, and well-watered or water-stressed. Germinated and non-germinated (viable, rotten and empty) seed percentages, germination rate and total phenolics were determined for both genotypes. Higher maturation temperatures increased seed germination percentage, but decreased germination rate, percentage of rotten and non-germinated viable seeds, and total phenolics. Elevated CO2 increased seed total phenolics. Water stress decreased the percentage of non-germinated viable seeds. Neither of the two latter factors affected other measured parameters. Seeds of the abi1-1 mutant had higher total phenolics. The fate of seeds was mostly affected by higher temperatures and water stress. Also, seeds of the abi1-1 mutant had higher germination rate, empty seed percentage and total phenolics than seeds of the WT genotype. Germination percentage was highest for the WT seeds that matured on the water-stressed plants that were grown under higher temperatures at ambient CO2. It can be concluded that higher temperatures had highest effects on seed germinability and other parameters, and elevated CO2 did not alleviate the negative effects of higher temperatures on seed viability.