[Cadmium Accumulation Characteristics of Four Herbs].

A pot-based experiment was conducted to study the Cd tolerance and accumulation characteristics of four invasive herbs (, and ) under exposures of 0 (T0), 5 (T5), 25 (T25), and 50 mg·kg (T50) soil Cd concentrations to screen for potential Cd accumulators for phytoremediation. The results showed that the biomasses of both shoots and roots of had no significant changes compared to the control (T0) samples under all Cd treatments, whereas the biomass of the other three Poaceae species significantly decreased under the T25 or T50 treatment. The results indicate that had stronger Cd tolerance than the other three species.

[Effect of nitrogen management modes on grain yield, nitrogen use efficiency and light use efficiency of wheat].

A nitrogen management experiment with three nitrogen levels (0, 120, and 180 kg·hm, namely N, N, N) and three nitrogen allocation modes (N: base fertilizer 100%; N: base fertilizer 70% + seedling fertilizer 30%; N: base fertilizer 60% + jointing fertilizer 40%) was conducted at four sites (Chongqing, Renshou, Guanghan and Xichang) during two consecutive years, the SPAD value, canopy photosynthetic rate (CAP), photosynthetically active radia-tion (PAR) interception efficiency and grain yield were determined, and the nitrogen use efficiency and PAR use efficiency were calculated. The results showed that the SPAD of upper-most three leaves, CAP, PAR interception efficiency and grain yield were promoted with increasing nitrogen fertilizer, but nitrogen fertilizer use efficiency, productivity efficiency, uptake efficiency and use efficiency were decreased. The promoting effects of nitrogen fertilizer postponing were different among nitrogen levels, with the highest SPAD in N treatment and the highest CAP in N treatment.