| Intercropping is one of the main agricultural measures to increase multiple cropping index and ensure high yield and good stability.Maize and peanut intercropping is an important mode between gramineae and legume crops,which provides the advantages of high yield,high efficiency,symbiotic nitrogen fixation,high resource utilization efficiency and optimized soil environment,etc.The research was conducted at the Corn Science and Technology Demonstration Park of Shandong Province and the State Key Laboratory of Crop Biology of Shandong Agricultural University from 2015 to 2016,and compactly planting summer maize variety DH 618 and early maturing and high-yield peanut variety HY 22 were used as the test materials.The density of summer maize was 105 000 plants·hm-2 while the density of peanut was 180 000 holes·hm-2,respectively.In 2015,Three planting methods(single maize,single peanut,intercropping maize and peanut?row ratio 4:6?and two nitrogen treatments(N240 controlled release urea 240 kg N hm-2,N0 no fertilization)were set.In2016,1/2 strips of each treatment which experimented in the first year experiment will be planted with maize peanut?single maize rotation,single peanut rotation,intercropping maize rotation,intercropping peanut rotation?,and the management of field fertilization was consistent with the experiment in 2015.The yield effects of monoculture,intercropping and rotation were systematically analyzed in terms of yield and economic benefit,plant traits,soil microenvironment,photosynthetic characteristics,antioxidant properties,nitrogen absorption and utilization,and nitrogen metabolism.The physiological and ecological basis of yield effect of intercropping system and the regulation effect of rotation were discussed in order to provide theoretical basis and technical guidance for efficient production of intercropping system.The main findings are as follows:1.Effects of maize and peanut intercropping on the system yields and economic benefitsIntercropping has different effects on the yield of maize and peanut.Intercropping significantly increased the yield of summer maize and reduced the yield of peanuts.The maize and peanut intercropping system of this experiment had yield intercropping advantage of 2.42–3.40 t·hm-2,and LER reached 1.17–1.20.In addition,intercropping increased the number of spikes and rows of maize during maturity,reducing the rate of empty rods significantly.For peanuts,intercropping reduced the rate of fruit ripening during ripe harvesting stage.The biological yield of summer maize increased significantly through intercropping,and this of peanut was decreased.The dry matter weight of each organ in the mature stage of maize,the dry weight of corn seed per plant,and the dry matter accumulation after the silking were increased through intercropping.The dry matter production capacity of maize plants increased,the photosynthesis products increased to the grain operation and distribution,and the yield increased.For peanuts,intercropping reduced the total dry weight and increased root dry weight and root-shoot ratio,indicating that intercropping promoted the transport and accumulation of photosynthetic products to the underground part of peanut.The intercropping system has the advantages of grain yield,biological yield and the high economic benefits.The two-year net output value of the intercropping system was 2507?·hm-22 and 5046?·hm-22 higher than that of single crop maize and single peanut.Nitrogen application and rotation have promoted the yield,yield composition,biomass yield and dry matter accumulation and distribution of maize and peanut,and can effectively alleviate the adverse effects of peanut in the inferior position.However,the two factors have different growth rates for crop yields,such as the impact on the yield of two crops:nitrogen application increased maize and peanut yields by 13.6%and 9.6%,respectively,while crop rotation increased maize and peanut yields by 6.6%and 4.3%.It indicates that the regulation effect of nitrogen application on crops is greater than that of crop rotation.2.Effects of maize and peanut intercropping on photosynthetic performance of cropIntercropping significantly improved the light condition of summer maize,which showed that the intercropping increased the chlorophyll content,canopy transmittance and actual photochemical efficiency,maximum photochemical efficiency,photochemical quenching coefficient,and reduced non-photochemical enthalpy of maize at various growth stages.The elimination coefficient is beneficial to the increase of the activity of RuBP carboxylase and PEP carboxylase in maize,which reduces the distribution ratio of 13C assimilates in stems and other leaves,and promotes its distribution to kernels.For peanuts,intercropping reduced Pn in peanuts,reduced chlorophyll a and total chlorophyll content,increased chlorophyll b content,and had an effect on chlorophyll fluorescence kinetics consistent with maize,reducing RuBP carboxylase and PEP carboxylase activity.Both nitrogen application and crop rotation improved the photosynthetic performance of crops,but the effect of the two on crop improvement was different.The former had a greater effect than the latter.The higher photosynthetic performance in the late growth stage laid the foundation for the formation of grain yield.3.Effects of maize and peanut intercropping on crop aging characteristicsIntercropping significantly increased the activities of SOD,POD and CAT in the late growth stage of summer maize.The three enzymes increased by 13.8%,19.8%and 15.6%,respectively,which significantly increased the soluble protein content in the panicles of flowering stage,increased by 12.1%,decreased the content of MDA,and self-flowering.From the period of waxy maturity,the MDA content of intercropped maize ear leaves decreased by 5.3%–12.8%,indicating that intercropping reduced the degree of leaf lipid peroxidation in the ear,which was beneficial to delay the senescence of leaves.For peanuts,intercropping significantly reduced SOD,POD,CAT activity and soluble protein content in leaves during peanut pod and full fruit stage,and increased MDA content in leaves.Nitrogen application and rotation have different effects on the senescence characteristics of crops.Nitrogen application significantly increased the activities of SOD,POD,CAT and soluble protein in leaves during the waxy stage of maize,and increased the SOD of leaves in the pod-forming and full-fruit stages of peanut.The activities of POD,CAT and soluble protein decreased the content of MDA in maize ear leaves and peanuts,and the regulation of antioxidant enzyme activity was not significant in the same treatment of each crop.Intercropping delays the senescence of leaves during the late growth period,which is conducive to the accumulation of photosynthetic products.4.Effects of maize and peanut intercropping on nitrogen absorption,translocation and utilization efficiency of cropsThe nitrogen accumulation per plant,total nitrogen uptake and the amounts of accumulated nitrogen after flowering were increased,and nitrogen metabolizing enzyme activity of ear leaves,nitrogen harvest index,nitrogen grain production efficiency,nitrogen physiological efficiency and agronomic efficiency of nitrogen fertilizer of maize were significantly improved,and nitrogen transfer amount was decreased.Maize kept high nitrogen accumulation in the vegetative organs of maize,prolonged the function of leaves to prevent premature senescence,and was beneficial to the synthesis of more photosynthetic products in the late growth stage of the plant.For peanut,intercropping decreased N uptake,NHI,ANUE and PNUE,and decreased the activity of nitrogen metabolizing enzymes in leaves,which was not conducive to N uptake and transport in peanut.From the point of view of the whole intercropping system,there was the advantage of nitrogen absorption intercropping,and the nitrogen absorption equivalent ratio was more than 1.Nitrogen application and rotation increased the nitrogen accumulation and GS,GDH,GOGAT activity of summer maize and peanut,decreased the nitrogen harvest index and nitrogen utilization efficiency of maize and peanut,and increased the nitrogen dominance and LER.Rotation cropping decreased the NHI and NUE of maize and peanut.The effect of nitrogen application on crop regulation was greater than that of rotation.The increase of nitrogen accumulation and the activity of nitrogen metabolizing enzymes in functional leaves and the decrease of nitrogen transport may be one of the reasons for the yield superiority of intercropping system.5.Effects of maize and peanut intercropping on rhizosphere soil of cropsThe available nitrogen and available potassium in soil were increased with intercropping.The intercropping system had high soil enzyme activity,soil urease,invertase and alkaline phosphatase.Both the catalase activity and the catalase activity were increased,and the effect on catalase activity was not significantly different between treatments.At the same time,intercropping also had significant effects on soil microbes.The bacteria,actinomycetes and symbiotic nitrogen-fixing bacteria were the most abundant in peanut soil,followed by intercropping system,the least in maize,and the intercropping of bacteria and symbiotic nitrogen-fixing bacteria in soil.The maize content was significantly increased by 34.6%and251.0%,respectively.The fungal content in the intercropped soil was significantly increased by 168.6%compared with the sole cropping in peanut,which indicated that the biological nitrogen fixation of peanut in the intercropping system increased the content of intercropped soil symbiotic nitrogen-fixing bacteria.Nitrogen application and rotation have improved effects on maize and peanut soils.The effects of the two on crop regulation were different.The effects on soil physical and chemical properties and soil enzyme activities were significantly better than the latter,while the latter had a deep effect on soil microbial content. |
PDF Full Text Request