ABSTRACT
Objective To provide a reference for the introduction and cultivation of Paris polyphylla var. yunnanensis in mid-south region of China, its resistance adaptation ability of high temperature was explored. Methods Strong seedlings of P. polyphylla var. yunnanensis were chosen and treated under different temperature conditions (25 ℃/20 ℃, 33 ℃/28 ℃, 39 ℃/34 ℃) for 7 d, and then investigated the effect on their related physiological indexes. Results The results showed that with the increase of temperature and stress time, the relative water content of the leaves of P. polyphylla var. yunnanensis decreased significantly under the treatment of 33 ℃/28 ℃ and 39 ℃/34 ℃ for 7 d, which was 17.38% and 58.25% lower than the control (25 ℃/20 ℃) respectively. The relative conductivity and the content of malondialdehyde (MDA) were both increased continuously, and it was respectively 3.59 times and 2.55 times higher than that of control under the temperature of 39 ℃/34 ℃. The content of soluble sugar decreased gradually at 39 ℃/34 ℃, which was 33.25% lower than that of the control. The changing of soluble protein content showed a wavy trend, and the fluctuation range of 33 ℃/28 ℃ treatment groups was larger than that of the control group, which increased to 1.32 times of the control after 7 d. The SOD increased firstly and then decreased. The peak value was reached after 4 d at 39 ℃/34 ℃, which was 2.35 times higher than that of the control group. The POD increased gradually in treatment group, which increased to 2.33 times of that in control group at 39 ℃/34 ℃ for 4 d, and the amplitude of the change gradually slowed down. Conclusion In the experimental temperature range, P. polyphylla var. yunnanensis grew well at 25 ℃/20 ℃, which was its optimal growth temperature. Long-term continuous temperature stress treatment at 33 ℃/28 ℃ can cause damage to plant leaves; High temperature at 39 ℃/34 ℃ will seriously damage the physiological and morphological structure of the plant, and even lead to the death of the plant.