Abstract: Three levels of low temperature stress (7 ℃/12 ℃, 5 ℃/10 ℃, and 3 ℃/8 ℃ in 24 hours) were installed in a climatic chamber to study their effects on the germination of tomato seeds. Low temperature stress did give impact on the germination. Compared with the control (18 ℃/25 ℃), the stronger the stress, the greater the impact was. When the daily minimum temperature was 5.0 ℃ or the daily average temperature was less than 10.0 ℃ (corresponding to treatment 7 ℃/12 ℃), the impact was more severe; and when the low temperature stress was encountered earlier, the impact was greater. When the low temperature stress was encountered within three days after sowing, the germination potential, germinating index, and germination rate of tomato seeds all had a sharp decrease. However, when the low temperature stress was encountered six days after sowing, the three indices were less affected. Low temperature induced the decrease of tomato seed α-amylase activity and the increase of relative ion leakage, and thus, decreased the degradation of seed starch and enhanced the permeability of seed cell membrane, which could be the main reasons for the impact of low temperature stress on tomato seed germination.

Key words: Schizotetranychus bambusae, Phyllostachys pubescens, Neosinocalamus affinis, Population parameters, Procreation isolation