(a) Representative images of WT, ppdk, pck1 and DM seedlings grown in the dark (left) or light (right) for 5 days. Scale bar, 1 cm. The effect of (b) increasing periods of darkness before being transferred to light, (c) reduced light intensity and (d) reduced day length on the frequency of establishment of WT, pck1, ppdk and DM seedlings (as defined by the proportion of seedlings that develop true foliage leaves within 4 weeks after germination). Data are shown as means±s.e. from three batches of a hundred seeds and asterisks represent a statistical difference from WT (P<0.05, LSD test, n=3). Light intensity was 160 μmol m−2 s−1 except in c.