The experiment of four treatments with low temperature and weak light on tomato was conducted in growth chamber taking “Jinfen 5” as material. The treatments included, 14/4℃ (maximum/minimum temperature, Tmax/Tmin)×400μmol·m-2·s-1 (photosynthetically active radiation, PAR), 14/4℃×200μmol·m-2·s-1, 12/2℃× 400μmol·m-2·s-1, 12/2℃×200μmol·m-2·s-1. Each treatment time was 2d, 4d, 6d, 8d, and 10d, respectively. The control (CK) was Tmax/Tmin 25/18℃, PAR 800μmol·m-2·s-1. The flowering and fruiting characteristic was recorded, and the yield and fruit quality was determined. The results showed that low temperature and weak light made the growth rate of buds and flowers delay significantly, and the stronger the stress level, the slower the growth rate. The bud number of the treatment (Tmax/Tmin 12/2℃, PAR 200μmol·m-2·s-1) was 0 during the whole treatment stage, and its flower number was the minimum, only 0.33 per plant during the whole treatment period. The number of tomato fruit showed an S curve with the time prolonged. The fruit-setting period was delayed significantly, when the treatment (Tmax/Tmin was 12/2℃, PAR was 400μmol·m-2·s-1) continued for 10 days, its fruit-setting period was delayed 10.5d than the CK. The tendency of malformed fruit increased as the degree of stress treatment. The yield and treatment time had a negative correlation. The yield reduction rate of tomato under low temperature and weak light reached more than 70% after 8 days, while there was no obvious effect on tomato yield under low temperature and weak light treatment within 2 days. Under the same temperature and the same treatment time, vitamin C, soluble solid content, and the ratio of sugar and acid decreased with the decline of PAR. Under the same PAR and treatment time, vitamin C, soluble solid content, and the ratio of sugar and acid decreased with the decline of temperature. However, the change trend of organic acid was inconsistent with vitamin C, soluble solid content, and the ratio of sugar and acid.
