Difference And Its Mechanism Of Interspecific Nutrition Competition In Different Intercropping Systems

In this study, two intercropping systems with widely-use and apparent yield advantage (i.e. spring wheat/ spring maize and spring barley/ spring maize intercropping) were used to investigate the growth of aboveground, nutrient uptake dynamics and temporal and spatial root distribution with the emphasis on competition for N,P,K and compensatory (recovery) ability, and the main results were following as:1) Intercropping advantage could be improved by cropping selection and fertilization and mulching. Land Equivalent Ratio (LER) of spring barley/ spring maize intercropping and spring wheat/ spring maize intercropping were 0.99-1.32 and 1.08-1.41 based on grain yield, and 0.98-1.31 and 1.06-1.42 based on biomass, respectively. Yield advantage of spring barley/ spring maize intercropping was apparent under fertilization and mulching for maize. Yield advantage of spring wheat/ spring maize intercropping, however, was apparent with only fertilization, and would be more advantage when maize was mulching at same time. Nutrition advantage was similar with yield advantage under the same condition in spring barley/ spring maize intercropping and spring wheat/ spring maize intercropping.2) Cultivars of maize had substantial effect on yield advantage of spring wheat/ spring maize intercropping. In different maize cultivar experiment, LER was 1.09-1.35 and 1.10-1.35 based on grain yield and dry matter yield, respectively. LER of intercropping with different maize cultivar changed in the order: Shendan No. 6>Yuyu No.22 > Zhongdan No.2 > Jiudan No.2 > Xinyu No.4, and the growth duration is in the same order with long duration for high LER, which indicates there was good relationship between intercropping advantage and biological characteristics of maize. Nutrient uptake characteristics were similar with yield advantage.3) Yield advantage of border rows of intercropped barley was much greater than that of intercropped wheat. Grain yield and dry matter in border rows of intercropped barley were 95.5%-116.9% and 114.5%-128.8% higher than its corresponding inner rows, while 57.6-81.6% and 66.0-106.5%, respectively, for intercropped wheat. Yield advantage of border rows of intercropped wheat increased with the length of maize growth duration. Advantage in border rows of nutrient uptake for intercropped barley was also greater than intercropped wheat. N,P,K acquisition in border rows of intercropped barley was 124.1%-149.3%, 133.5%-149.1% and 147.2%-157.9% higher than corresponding inner rows, while 74.5%-115.5%, 76.7%-115.1% and 80.4%-137.4%, respectively, for intercropped wheat. N,P,K nutrient advantage in border rows of wheat intercropped with maize of late growth duration was apparently higher than that of wheat intercropped with maize of early growth duration.4) When fertilized and mulching for maize, yield advantage of spring maize/ spring barley intercropping was mainly attributed to aboveground, 80% from aboveground and 20% from underground. With fertilization and non-mulching for maize, the relative contribution of yield advantage of spring wheat/ spring maize intercropping from aboveground and underground accounted for 75% and 25%, whereas 2/3 and1/3 with both fertilization and mulching for intercropped maize.5) Barley and wheat were more competitive than maize; however, barley had much more competition power than wheat. There were two main mechanisms. First, barley was more competitive than...