关键词: 希蒙得木, 干旱胁迫, 光合特性

Abstract: Effect of different drought stress[continuous drought 0 d(D₀), 6 d(D₆), 12 d(D₁₂), 18 d(D₁₈)] on photosynthetic characteristic of two-year-old S. chinensis seedlings by a pot experiment.The results showed that the leaf relative water content(LRWC) significantly decreased with the decrease of soil water content(SWC), and a highly significant positive correlation was observed between SWC and LRWC.The chlorophyll content, net photosynthetic rate(P_n), stomatal conductance(G_s), transpiration rate(T_r) and maximum net photosynthetic rate(P_nmax) decreased with the increase of drought stress time, while dark respiration rate(R_d) increased.Intercellular CO₂ concentration(C_i) decreased under D₁₂, but increased rapidly under D₁₈.Water use efficiency(WUE) showed the opposite side to C_i.The decrease of photosynthetic capacity of S. chinensis seedlings under D₁₂ was mainly due to stomatal limitation, while non-stomatal limitation might be the main reason under D₁₈.In addition, apparent quantum yield(AQY) and light saturation point(LSP) decreased with the increase of drought stress, while light compensation point(LCP) increased.In conclusion, the leaf of S. chinensis seedlings under drought condition showed serious water deficit in leaf, and significantly decrease of photosynthetic carbon assimilation capacity and light environment adaptability.These responses might be the adaptation strategy of seedlings under drought stress.

Key words: Simmondsia chinensis, drought stress, photosynthetic characteristic