| Intercropping technology can make different kinds of crops multilayered take full advantage of light resources overground and water and nutrient resources underground, and can improve colony structure of crop, increase defense mechanisms of group, reform stress tolerance and disease resistance of population, enhance the yield of composite group in intercropping system.In addition, close planting was one of the important measures for high yield, and producers usually tended to improve yield by optimizing the density of main plant. However, the performance of crop yield and traits, the role of different factors, the level of close planting to be studied under high density conditions in intercropping system. Therefore, In order to provide theoretical and practical support for optimizing competition and complementary of crops,realizing the efficient use of resources, we explored the influence of light, water, nutrient three different factors under close planting condition and the level of close planting in maize/pea intercropping system. The main conclusions are as follows:1. Maize/pea intercropping system had a greater contribution to the dry matter accumulation during the pea harvest and after the pea harvest and the accumulation of nitrogen,and increased density of maize was beneficial to improve the dry matter accumulation and competitive. Before the pea harvest, the performance of dry matter accumulation: monocropped pea > intercropping > monocropped maize, the maximum accumulation of dry matter were medium density treatment(60000 plant·hm-2) and high density treatment(75000 plant·hm-2);During the pea harvest and after the harvest, the dry matter accumulation were shown as:intercropping > monocropped maize > monocropped pea and monocropped maize >intercropping, high density treatment(75000 plant·hm-2) of dry matter accumulation was higher than other treatments. Moreover, the accumulation of nitrogen of crops showed that intercropping group were higher than monocropped maize and monocropped pea 5.74% and28.68%; The maximum accumulation of nitrogen of crops were medium high density treatment(67500 plant·hm-2) and low density treatment(52500 plant·hm-2) in monocropped and intercropping system.2. Compared with monocropped, intercropping system had no beneficial effect on the improvement of photosynthetic active radiation, light transmission rate dynamic at the bottom,maize leaf azimuth angle and soil moisture, but it can effectively optimized leaf inclination angle of maize, evaporation of crop, soil water consumption, E/ET and soil nitrogen; Under the condition of increasing the density of maize, only the light transmittance and the soil water content were increased, the other indicators of light, water and nutrient had no obvious advantage. It was conducive to reducing the loss of light at the bottom under high density, the leaf inclination angle was decreased with the increase of maize density. What's more, compared with the monocropped pea, soil moisture of 0-120 cm profile was increased by 5.38% of intercropping system, the evaporation and soil water consumption of intercropping were higher than monocropped 12.68%-35.09% and19.23%-22.98% under four density of maize in relative area, the E/ET of interropping was lower than monocropped 3.12% except in high density treatment(75000 plant·hm-2), it was higher than the other density treatment 1.06%-13.99%.Furthermore, Intercropping system had advantages of nitrogen in the 0-20 cm and the 20-40 cm profile, the maximum of soil total nitrogen and soil ammonical nitrogen were in low density of maize, but soil nitrate nitrogen had different performance, soil total nitrogen, soil nitrate nitrogen and soil ammonical nitrogen in the 0-20 cm was higher than that in the 20-40 cm, pea belt was higher than maize belt.3. Intercropping can significantly improve yield of crop, LER and NUE, but it had little effect on the light use efficiency and WUE; The increase of density of maize had an important contribution to yield of crop, LER, WUE, NUE. The total grain yield and total biomass yield of intercropping was markedly superior to mono-cropping pea, in relative area, compared with mono-cropping maize, the grain yield and the biomass yield of maize in maize/pea intercropping were enhanced by 19.61% and 17.24%; The total grain yield of intercropping, the grain yield of maize and pea in maize/pea intercropping, and the total biomass yield of intercropping, the biomass yield of maize and pea in maize/pea intercropping, the biomass yield of monocropped maize and pea was largest in high density treatment(75000 plant·hm-2) with four different maize density. Besides, except the low density of maize, the LER higher than 1 under the other density treatments(52500 plant·hm-2), the LERY under high density treatment(75000 plant·hm-2) and the LERB under medium high density treatment(67500 plant·hm-2) showed advantages.Furthermore, light use efficiency of intercropping was higher than monocropped pea 0.24% and the maximum light use efficiency of maize appeared medium high density treatment(67500plant·hm-2). In addition, the WUE of monocropped maize in four density were ranked in top 4,significantly higher than intercropping and monocropped pea, the WUE in medium high density treatment(67500 plant·hm-2) level were the biggest. Besides, the NUE of intercropping of was significantly higher than that monocropped 42.36%, and the maximum NUE of intercropping appeared high density treatment(75000 plant·hm-2).4. Except soil nitrate nitrogen and soil ammonical nitrogen, the other factors have significantly positive correlation with the yield, the consumption of light, water and nutrients is proportional to the increase of output, the more dry matter accumulation and accumulation of nitrogen of crops, the more yield. The incidence matrix of different factors and yield showed that the rank of effects of different factors on crop yield: accumulation of nitrogen of crops > soil water consumption > soil total nitrogen > soil moisture > photosynthetic active radiation > soil ammonical nitrogen > dry matter accumulation > dry matter accumulation. In short, the influence of light, water, nutrients three key factors under different density in maize/pea intercropping system ranking: water > light > nutrient. |
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