Mechanism On Competition And Complementation In Different Intercropping Patterns For Cassava And Peanut

Cassava (Manihot esculenta Crantz) is one of important tropical crops in the world.Because solo-cropping had low economic benefit, farmers had little enthusiasm to plant it.Cassava and other crops intercropping could reasonably use of land and increased economic output. Peanut was the first important oil crops in south China. Because peanut had characteristics of shorter growth duration, lower plant height, it was suitable for intercropping with many other crops, such as grain fruit and vegetables. Cassava/peanut intercropping systems were generally used in the cassava production areas in China. Solar,hot and nutrient resources utilization and effect on the soil fertility of three different intercropping modes were studed in this paper.The main findings were as follows:Three cassava/peanut intercropping modes could improve land equivalent ratio,output equivalent ratio, ATER and LUE. Nitrogen, phosphorus and potassium absorption equivalent ratio of three intercropping modes were larger than 2, that was to say, these modes had intercropping advantage to absorb nutrient resources. Cassava actual yieldlosses(AYLC) of three intercropping modes were greater than 1, and AYLP were less than 1,in other words, intercropping increased cassava yield of individual plant, while decreased peanut yield of individual plant. Cassava was competitive advantage species in three intercropping modes, peanut was competitive disadvantage species throught aggressivity and competitive raito.The partial land equivalent ratio of the C2P3 mode was greatest value in three modes,so the intercropping advantage of cassava was strongest in three modes. Peanutin the C2P3 and C2P4 models had intercropping advantages. From the competition index, cassava of the C2P3 had the strongest competition ability in three intercropping modes. AYL of the C2P3 mode had maximum value in three intercropping modes, which was 0.46. LER,output equivalent ratio, LUE and SPI of the C2P3 mode were the largest in three modes,That was to say, the intercropping advantage of the C2P3 modes was the strongest.During the 92 days of planting, the value of the actual output was greater than the value of expected output of peanut, which showed that the peanut had the compensation effect. After planted for the 120 days, peanut in the C1P2 and C2P4 modes had the compensation effect firstly, then it had the competition effect. Actual output and the expected output of the C1P2 and C2P3 modes had no difference in the symbiotic period,while after the peanut was harvested, the increasing rate of the cassava actual output were faster, which indicated the modes had the competition effect firstly, then to recovery effect.The maximum accumulation rate of dry matter of peanut in the C2P3 and C2P4 modes were greater than the corresponding monoculture crops, and the time of the cassava maximum dry matter accumulation rate in the C1P2 and C2P3 modes was later than that of monoculture, while the time of the peanut maximum dry matter accumulation rate was earlier than that of the monoculture. The modes had the greater niche separation in time and reduce the competition between intercropping crops.Light saturation point of cassava had no significant difference in three modes and the monoculture, and light compensation point and light saturation point of peanut had no significant difference too after 75 days planted, while light compensation point of three modes were significantly lower than that of peanut monoculture. The light compensation point of C2P3 mode was lowest, AQY was largest, which could extend effective light time,increase light use efficiency of peanut.Intercropping could improve root total absorption area and root volume of cassava and peanut later period, and root absorbing surface area and volume of cassava in the C2P4 mode was best in three modes. Theory cumulative amount of nitrogen and phosphorus of cassava in three modes were higher than that of monoculture cassava, while theory cumulative amount of nitrogen and phosphorus of peanut in three modes were lower than that of monoculture peanut, which showed that peanuts was competitive disadvantage crop on the nitrogen and phosphorus nutrient resources in the symbiotic period, cassava was competitive advantage crop.N, P, K absorption efficiency of the C1P2 and C2P4 models was higher, while the N, P, K absorption efficiency of C2P3 model were lower. N, P, K partial absorption equivalent of cassava in the C2P4 model were the highest, N, P, K partial absorption equivalent of peanut in the C1P2 model were the highest.Competitive capability of nitrogen, phosphorus and potassium of cassava in three modes were weaker than those of peanut after 75 days planted. That was to say, cassava had competitive disadvantage in nutrients, and had the tendency of C1P2<C2P3<C2P4.After 110 days planted, competition ability to nitrogen, potassium and potassium of cassava were all better than those of peanuts, had the tendency of C1P2 < C2P3<C2P4.The time of maximum N accumulation rate of cassava was similar to monoculture cassava,the time of maximum phosphorus and potassium accumulation rate of cassava was delayed compared with monoculture cassava. The time of maximum nitrogen, phosphorus and potassium accumulation rate of peanut was brought forward, which could realize nutrient resources complement each other in time.Soil basic physical and chemical properties, soil enzyme activity and the total soil microbial were measured by principal component analysis and comprehensive evaluation.The results showed that intercropping could improve the soil fertility of cassava rhizosphere soil, rhizosphere soil fertility of cassava had the tendency of C2P4>C2P3>C1P2,while the rhizosphere soil fertility of peanut in C2P4 modes was better than that of monoculture peanut only.