关键词: 预培养, 氮素含量, 土壤冷储存, 氮素转化, 森林土壤

Abstract: This study investigated the mechanism of resistance to cadmium (Cd) after chitosan application. Two different varieties of maize, “Zhengdan 958” (Cdtolerant) and “Dongnong 253” (Cdsensitive) were chosen as experimental materials. Effects of 100 mg·L^-1 of chitosan application on plant growth, root feature parameters (root length, root surface, root volume, average diameter, tip number), cell membrane permeability of root, activities of root antioxidant enzymes (SOD, POD), leaf chlorophyll content, photosynthetic parameters (P_n,G_s, T_r, C_i) and the maximal photochemical efficiency (F_v/F_m) of leaf were measured under 80 mg·L^-1 Cd²⁺ stress. The results showed that 80 mg·L^-1 Cd²⁺ inhibited the growth of maize seedlings, destroyed the stability of root cell membrane and antioxidant enzymes system, and had a negative effect on the photosynthesis of leaves. The chitosan application led to a marked increase in root length, root surface and root volume, alleviating the growth inhibition under Cd stress. Chitosan treatment played an important role in stabilizing root plasma membrane structure and function, decreased the malondialdehyde (MDA) content and relative conductivity of root system under Cd stress, inhibited the production of ROS, and increased the activity of SOD and POD. Chitosan treatment increased the contents of chlorophyll a (Chla) and chlorophyll b (Chlb) in leaves, increased the photosynthetic rate and F_v/F_m, which enhanced the photosynthesis of leaves, so as to alleviate the seedling growth inhibition under Cd stress. Dongnong 253 (Cdsensitive) showed a better effect than Zhengdan 958 maize variety. The results provide a theoretical and experimental basis for the application of chitosan to maize Cdresistant production.

Key words: pre-incubation, forest soil., nitrogen transformation, soil cold storage, nitrogen content