A smoke-derived butenolide, 3-methyl-2H-furo[2,3-c]pyran-2-one, has previously been shown to improve seedling vigour. The aim of this study is to examine the effect of hydropriming and butenolide priming treatments on seedling emergence and growth under different sowing depths at 20 and 25 degrees C in two melon (Cucumis melo L.) seed lots of high and low quality. Seeds are subjected to hydropriming (21 h at 25 degrees C) and butenolide priming (10(-7) M, 21 h at 25 degrees C) and sown at a depth of 4 or 8 cm in peat moss (field capacity, 64% water by mass). In general, seedlings from butenolide-primed and hydroprimed seeds are superior to those of the control. At 20 degrees C, the effect of butenolide priming is more pronounced than that of hydropriming and the control, particularly for the seeds sown at a depth of 8 cm. Butenolide priming has a 'repair-inducing' effect and enhances the low-quality seeds more than those of the high-quality seed lot, an effect which is more obvious at 20 degrees C than 25 degrees C. It can be concluded that butenolide priming may be a useful tool to enhance melon seedling performance under low temperature sowing conditions.