Objective   Resistance to low temperature and reduced light exposure of pepper plants were studied for breeding purpose.

  Method   Seedlings of 6 pepper cultivars of different varieties were exposed to controlled day/night conditions of 25℃/15℃ and 300 μmol·m⁻²·s⁻¹ as control or 15℃/5℃ and 100 μmol·m⁻²·s⁻¹ for treatment. Growth and photosynthetic characteristics of the seedlings cultivated under the conditions were monitored.

  Result   Comparing to the seedlings grown under the normal 25℃/15℃ and 300 μmol·m⁻²·s⁻¹ conditions, those exposed to the reduced temperature and light showed reductions in plant height, stem diameter, leaf area, and plant dry weight. Of the various cultivars, Yangjiao No. 5 was least affected by the treatment. The cold injury indices of the cultivars ranked as Yangjiao No. 5＜Kejizhiguang No. 9＜Sujiao No. 5＜Juwuba No. 5＜Haihua No. 3＜Qiemen sweet pepper . The leaf Pn, Gs, Tr, Fv/Fm, Φ_PSII, ETR, and qP decreased by the treatment and were least affected on Yangjiao NO. 5 among all cultivars. The reduced temperature and light exposure also induced reductions on the chlorophyll content in the plants. Of which, Yangjiao No. 5 exhibited a higher resistance. There was a negative correlation between the Pn, Gs, Tr, Fv/Fm, Φ_PSII, ETR, and qP and the cold injury index, but a positive one between them and the dry weight of the pepper seedlings when exposed to low temperature and reduced light.

  Conclusion   Exposure to low temperature and reduced light hindered the growth and photosynthesis of the pepper seedlings of different varieties with variances. Among the 6 cultivars, Yangjiao No. 5 appeared to withstand the adverse conditions better than the others and sustain a near normal growth.