Effect of light conditions on the development of the inflorescence in tomato

By growing tomato plants (Lycopersicon esculentum Mill.) in 4 different light regimes (2 photoperiods — 8 and 16 h — combined with 2 light intensities — 9,000 and 18,000 ergs cm^?2 s^?1, it was shown that increasing light integrals hastened flower initiation, greatly promoted the development of the inflorescence and increased the rates of leaf production and the growth of the stem. In similar light integrals, flower initiation was earlier and inflorescence development far better in short photoperiods than in long ones; the rates of leaf production were almost the same and stem growth was greater in long days.Transfer experiments from favourable to insufficient light conditions and inverse transfers at different times during the life of the plant indicated that light conditions were critical at the time of, and after, the macroscopic appearance of the inflorescence. At that stage, a transfer to low light conditions for 10 days induced complete abortion of the truss in our growth conditions. The effect of a transfer from insufficient to favourable light conditions was slower since at least 15 days in these latter conditions were required in order to achieve the development of the inflorescence.