Abstract: The responses and adaptation strategies of plants to the variations of precipitation pattern can affect the ecosystem processes such as carbon sequestration. In this paper, a pot experiment was conducted to study the variations of the net photosynthetic rate (P_n), maximum photochemical efficiency of PSII (F_v/F_m), and biomass allocation of four desert herbaceous plants (Kochia scoparia, Atriplex patens, Salicornia europaea, and Salsola lanata) under four simulated precipitation patterns (wet treatments 20 mm × 1 per week versus 10 mm ×2 per week, and drought treatments 12 mm × 1 per week versus 6 mm × 2 per week). Overall, the P_n of the plants peaked on the 2nd day after the treatments, and the plants maintained a higher level of single leaf P_n. The F_v/F_m of S. europaea and S. lanata in all treatments was kept within an optimal range. The specific leaf area (SLA) and specific root length (SRL) were less affected by the treatments. The growth of K. scoparia was limited by phosphorus, while that of the other three species was limited by nitrogen. The precipitation amount dominated the total biomass and the leaf, shoot, and root biomass, whereas the precipitation frequency regulated the biomass allocation in plant above and belowground parts. Under a given precipitation amount, the increase of precipitation frequency promoted more biomass allocation in plant belowground part.

Key words: photosynthesis, respiration, stable isotope, environmental factors.