Effects of Nitrogen Levels and Root Barriers on Nitrogen Absorption of Intercropping Triticum aestivum and Vicia faba

Pot trials of Triticum aestivum and Vicia faba intercrop with 3 root barriers (no barrier, mesh barrier, polythene barrier) and 3 nitrogen levels (N/2, N, 3N/2) were carried out in the greenhouse. Dry matter and the nitrogen absorption and nutrient competition ratio (NCRcs) were analyzed to study the effects of different planting patterns and nitrogen application levels on nitrogen nutrition accumulation and nutrient competition in Triticum aestivum and Vicia faba. The results showed that different nitrogen levels and root barrier altered dry matter of Triticum aestivum and Vicia faba, the mesh barrier increased dry matter than no barrier and polythene barrier 60.8%, 61.46%; 71.19%, 73.42%; 63.02%, 61.54% under deficiency, adequate and high nitrogen level (N/2, N, 3N/2) at wheat jointing stage. Under deficiency nitrogen level, dry matter of no barrier Vicia faba decreased by 15.46% and 20.68% than that of mesh and polythene barrier. Under recommended nitrogen application rate, dry matter of mesh barrier decreased by 24.53%, 23.11% and 26.66%, 26.96% than that no barrier and polythene barrier at heading stage and maturity stage of Vicia faba. However, there were no significantly differences among all 3 root barriers under high nitrogen level. Different nitrogen levels and root barriers also altered nitrogen absorption of Triticum aestivum and Vicia faba. Under deficiency nitrogen condition, the nitrogen absorption of no barrier wheat were significantly higher than those of mesh and polythene barrier, but this advantage was not obvious with the increasing of nitrogen application rate. Under the conditions of deficiency and high nitrogen, there were not significantly differences of Vicia faba in the nitrogen absorption among 3 root systems (PB, MB, NB), however, under the recommendation of nitrogen application, nitrogen absorption of polythene barrier Vicia faba increased sharply, especially in the grain expansion stage, which increased by 29.03% and 26.48% respectively compared with the no barrier and mesh barrier. Under deficiency and adequate nitrogen application rates, the nutrient competition ratio (NCRcs) of wheat was dominant relative to Vicia faba between mesh barrier and polythene barrier system and between no barrier and polythene barrier system at jointing, booting and filling stages of Triticum aestivum.