Abstract: In this paper, taking mulberry seedlings as test material, the effects of diffierent concentration alkaline salt (Na₂C0₃)stress(Density of concentration was 100 mmol/L and value of pH were 7.0,8.0,9.Oand10.0) on chlorophyll content relative water content, cell membrane permeability changes and Chlorophyll fluorescence haracteristics in mulberry seedlings were investigated. The results shoved that under the alkaline salt stress with pH values in 7. 0一9. 0,chlorophyll content and relative water content were reduced smaller malondialdehyde contents were no apparent increased and peroxidation of membrane were no occurred significantly. Meanwhile,the inhibitions of PS, physiological function were also not being obvious in leaves of mulberry seedlings. However the leaves of mulberry seedlings could protect normal physiological function of PS, reaction centers by non}adiative energy dissipation mechanism which was xanthophyll}egulated thermal energy dissipation as the main,thus leaves of PS could guarantee the normal capacity of electronic transport and utilization of solar energy. Namely,the PS in Leaves of Mulberry seedlings had an alkaline salt-tolerance ability in some degree. But when the pH up to 10. 0,membrane systems in leaves of Mulberry seedlings were damaged, leaves water loss were seriously, and Per unit area of chlorophyll content were appreciably reduced which reducing of chlorophyll a content particularly clear. Furthermore,photosynthetic electron transports were hindered in leaves of Mulberry seedlings, and the absolute energy could used in photosynthetic electron transports imcompletely. The non-radiative energy dissipation mechanisms by xanthophyll cycle were inhibited simultaneously, which resulted in an accumulated excess light energy(1-q_P)/NPQ in the leaves. Then closure and deactivation of PS II reaction centers accelerated rapidly,which might be a way to alleviate the pressure on PS reaction centers, but at the same time decreased the capacity of solar energy utilization in particular to high light intensity utilization in the leaves of Mulberry seedlings.

Key words: Mulberry, Alkali salt stress, pH value, ChlorophyⅡ fluorescence

CLC Number: 

• Q945.1