| General Secretary Xi Jinping emphasized that under the premise of ensuring food security,our country must take the path of ecological priority,green and low-carbon development.Promoting agriculture through science and technology is the only way to accelerate the development of modern agriculture,and exploring a new mode of green and efficient planting is an effective way to develop modern agriculture.Jiangsu is located along the Yangtze River Delta and belongs to the East Asian monsoon climate zone.It is in the climate transition zone between the subtropical and the warm temperate zones.It has abundant light,temperature and water resource,and several other natural resource enrichments for agriculture production is relatively favorable.Good light and temperature resource conditions have formed a paddy field planting model dominated with double-cropping of rice and wheat,and a dry field planting model of multi-cropping of special grain and economic crops such as maize,soybean,and faba bean.However,there are problems such as excessive application of chemical fertilizers and serious non-point source pollution in the process of rice and wheat doublecropping in paddy fields.The dry field planting model has problems such as low utilization of light and temperature resources,unreasonable allocation of multi-cropping stubble,and ineffective combination of land use and land cultivation.These problems seriously restrict the green,efficient and sustainable development of modern agriculture in Jiangsu Province.Therefore,this paper optimizes the double-cropping model of rice and wheat through the study of reduced application technology of nitrogen chemical fertilizer for rice and wheat,and highyield technology of returning rice straw to wheat field in Jiangsu riverside region.At the same time,this paper evaluates a multi-cropping and high-efficiency compound planting model in dry fields in Jiangsu riverside region with wheat,fresh faba beans,fresh maize,and fresh soybeans as the main component,and carried out research on the coordination process of light.temperature and water resources and crop responsed ecological mechanism between seasons and within the system,and proposed regulation technology of efficient utilization of resources,and establishes a green and efficient planting model with efficient utilization of resources.These provides important theoretical basis and technical support for the construction and promotion of the new multi-green and efficient planting model in Jiangsu province.The main findings are as follows:1.Optimization of rice and wheat double cropping planting model and its mechanism in Jiangsu riverside region(1)Effect and mechanism of reduced application of chemical nitrogen fertilizer on rice growthAiming at the problem of excessive application of chemical nitrogen fertilizer to rice in rice wheat double cropping,the field plot experiment was conducted to study the effect of nitrogen base tiller fertilizer reduction and organic fertilizer replacing chemical nitrogen fertilizer on rice yield and growth.Compared with the conventional fertilization treatment,the reduced application of nitrogen based and tiller fertilizer reduced the peak tiller number of rice,had no effect on the emergence period of peak tiller number of rice,andincreased the yield of heading.Reducing the nitrogen base fertilizer by 50%increased leaf base angle and leaf opening angle,reduced leaf sag,improved panicle rate and 1000 grain weight of rice,and increased or stabilized the yield of rice.No inorganic nitrogen fertilizer or organic fertilizer application instead of inorganic nitrogen fertilizer increased the peak tiller number of rice,but delayed the emergence time of peak tiller number.Replacing inorganic nitrogen fertilizer with organic fertilizer caused the leaf base angle of flag leaf,second lower leaf and third lower leaf to become smaller at heading stage,increased leaf length of the third lower leaf,and delayed the decline rate of chlorophyll content of the top three leaves after heading.The substitution of organic fertilizer for 90 kg/hm2 and 135 kg/hm2 of chemical nitrogen fertilizer increased the number of effective panicles and 1000-grain weight,and the yield of rice was increased by 4.27%and 6.06%,respectively,compared with conventional fertilization.(2)Mechanism of rice straw returning to the field on wheat growth and development and nitrogen fertilizer reduction measuresIn view of the problems such as the reduction of wheat seedling emergence rate caused by rice straw returning to the field and the unreasonable operation of wheat nitrogen fertilizer in rice wheat double cropping,pot experiments and field plot experiments were used to analyze the allelopathic effect and regulation way of rice straw extract on wheat seed germination and seedling growth,and to study the effect mechanism of returning rice straw to the field on wheat grain development,and to study the efficient operation measures of wheat nitrogen fertilizer reduction under the condition of rice straw returning to the field.Allelopathy of rice straw extract on wheat seed germination and seedling growth is an important reason for the decline of wheat seedling emergence rate caused by rice straw returning to the field.The rice straw extract inhibited α-amylase activity and starch decomposition during wheat seed germination,and inhibited photosynthesis and nutrient element absorption at seedling stage.The allelopathic inhibition is enhanced with the increase of rice straw extract concentration,and the inhibition of wheat seed germination and seedling growth is not significant with low concentration of extract.Transcriptome analysis showed that 1806 differential genes were upregulated and 2778 were down-regulated during germination,and the differentially expressed genes mainly reflected in biological processes such as reaction to acidic chemicals.detoxification,antioxidant activity,gibberellin biosynthesis process α-amylase activity.At seedling stage,3370 differentially expressed genes were up-regulated and 2275 differentially expressed genes were down-regulated.The differentially expressed genes were mainly reflected in biological processes such as nitrogen utilization,sucrose transport,phosphate ion transport,photosynthesis,hormone level regulation,detoxification.Rice straw returning depth is an effective way to increase emergence rate wheat seedlings.Compared with other treatments,incorporating rice straw into the soil at a depth of 15cm increased yield of wheat per plant and total starch content,decreased amylose content,accelerated the development of endosperm,increased the amount of B-type starch granules at 17 d and 27 d after flowering,increased the proportion of small B-type starch particles,reduced relative crystallinity,and increased the ratio of amorphous structure to ordered carbohydrate structure in the external region of the granules.Pasting parameters including peak,breakdown,final,and setback viscosities increased,whereas pasting time and temperature decreased.Under the condition of rice straw incorporation into the field,the replacement of inorganic nitrogen fertilizer with organic fertilizer increased panicle formation rate and effective panicle number of wheat.Replacement of 21 kg/hm2 inorganic nitrogen fertilizer with organic fertilizer as the base fertilizer resulted in 1.8%increase in the yield of wheat.Under the condition of rice straw incorporation into the field,the reduced application of basal tiller fertilizer and tiller fertilizer increased 1000-grain weight of wheat and number of grains per panicle.When the amount of nitrogen fertilizer of basal fertilizer and jointing booting fertilizer was not reduced,the nitrogen reduction of tiller fertilizer by 50%increased the number of effective panicles and panicle rate of wheat,and improved the agronomic utilization rate of nitrogen fertilizer of wheat.When the basal and tiller fertilizers were reduced,the planting density of wheat was increased at the same time to achieve increased wheat yield.When the planting density was increased to 3 million plants/hm2,the amount of nitrogen fertilizer without base fertilizer,tiller fertilizer and jointing booting fertilizer was not reduced,and the wheat yield increased by 8.07%.2.Establishment and Mechanism of a Green and Efficient Planting Model with Wheat and Fresh Maize as the Subject in dry field of Jiangsu riverside regionIn agricultural production,there are some problems such as the loose connection of the dry field planting mode and the low utilization rate of light and temperature resources,as well as the lack of a planting mode that gives consideration to both food crops and cash crops.The three-crop planting mode "wheat-fresh maize/fresh soybean" and "wheat-fresh maize/fresh maize" were established.The effects of planting patterns on light,temperature,water resources and nutrient utilization were studied.From 2016 to 2020,the yield of the "wheat-fresh maize/fresh soybean" planting model increased by 4804 kg/hm2 to 11979 kg/hm2,and the biomass increased by 4389 kg/hm2-10425 kg/hm2 compared with the traditional double cropping planting mode(wheat/fresh soybean).With the increase of planting years,wheat yield increased by 296.30 kg/hm2-664.45 kg/hm2 under three-crop planting model.Compared with "fresh maize/fresh maize","fresh maize/fresh soybean" increased production of fresh maize by 5.60 kg/hm2-207.27 kg/hm2,annual photosynthetic utilization rate by 6.10%-9.69%,and the annual light energy production efficiency was 1.57 g·MJ-1-3.57 g·MJ-1,and effective accumulated temperature production efficiency by 1.65 kg·hm-2·℃-4.30 kg·hm-2℃-1,and the apparent economic utilization rate of precipitation by 0.44 kg·mm-1·hm-2-10.26 kg·mm-1·hm-2.The yield of fresh maize decreased with the decrease of photosynthetic radiation distribution rate and effective accumulated temperature distribution rate in "fresh maize/fresh maize" planting model.The annual economic benefit of the triple cropping model with wheat and fresh maize as the subject increased by 12532.1 yuan/hm2 to 34192.8 yuan/hm2 compared with the double cropping model.The main reason for the increase in economic benefits is that the annual output value of the triple cropping mode has significantly increased,which increases the yield of fresh food crops of the first crop compared with the double cropping mode.The economic benefit of "wheat fresh maize/fresh soybean" is 4159.2 yuan/hm2-16682.7 yuan/hm2 higher than that of "wheat fresh maize/fresh soybean".mainly because the unit price and output value of fresh soybean are significantly higher than that of fresh maize.The annual nitrogen,phosphorus and potassium uptake of the three-crop planting model with wheat and fresh maize as the main components were significantly higher than those of the control,but the annual nitrogen,phosphorus and potassium uptake efficiency was lower than that of the control.The nitrogen utilization rate of wheat in the triple cropping mode is 7.85%-11.40%higher than that in the double cropping mode,the phosphorus utilization rate is 4.61%-11.39%higher than that in the double cropping mode,and the potassium utilization rate is 4.61%-11.39%higher than that in the double cropping mode.The nitrogen,phosphorus and potassium absorption efficiency of "wheat-fresh maize/fresh soybean" gramineous and leguminous composite planting mode is higher than that of "wheat-fresh maize/fresh maize"gramineous composite planting mode.The soil organic matter of the triple cropping model increased by 12.28%-12.56%,the total nitrogen of the soil increased by 10.98%,the total phosphorus increased by 8.00%-12.00%,the alkali hy drolyzed nitrogen increased by 13.91%15.21%,the available phosphorus increased by 28.61%-36.36%,and the available potassium increased by 3.57%-1 0.43%.3.Establishment and Mechanism of a Green and Efficient Planting Model with Fresh Maize and Fresh faba bean as the Subject in dry field of Jiangsu riverside regionIn agricultural production,there are some problems such as the loose connection of the dry field planting mode and the low utilization rate of light and temperature resources,as well as the lack of a planting mode of cash crops.The three-crop planting mode "fresh faba bean/fresh maize-fresh soybean" and "fresh faba bean/fresh maize-fresh maize" were established.The effects of planting patterns on light,temperature,water resources and nutrient utilization were studied.The results of positioning test research from 2016 to 2020 were as follow:(1)Compared with the traditional double cropping mode(faba bean/maize),the annual yield of the triple cropping mode,which is dominated by fresh faba beans and fresh maize,has increased by 6469 kg/hm2-33682 kg/hm2,the annual output value has increased by 28101 yuan/hm2-81740 yuan/hm2,and the annual economic benefit has increased by 15201 yuan/hm2-65571 yuan/hm2.(2)Compared with the traditional double cropping mode(faba bean/maize),the triple cropping mode with fresh faba bean and fresh maize as the main crops increased the photosynthetic utilization rate by 8.50%-13.49%,the effective accumulated temperature production efficiency by 10.58%-15.32%,and the precipitation utilization rate by 8.84%-28.45%.(3)The planting mode of "fresh faba beans/fresh maize-fresh soybeans" increased the nitrogen utilization rate by 13.40%-71.43%and the potassium utilization rate by 8.27%-25.89%compared with the control.(4)The content of soil organic matter in different planting modes has an increasing trend from 2017 to 2020,with an increase range of 7%-35%.From 2018 to 2020,pot experiments were conducted to study the effects of interaction between the underground parts of fresh faba bean intercropping and fresh maize on yield and nutrient absorption and utilization.The main results were as follow:(1)Compared with the plastic isolation treatment,no root isolation treatment significantly improved the nutrient accumulation,soil nutrient content,photosynthesis,yield,biomass,plant height and 100-grain weight of fresh faba bean and fresh maize.The yield of fresh faba bean without root isolation was 3.67%higher than that of gauze isolation,and 7.04%higher than that of plastic isolation.The yield of maize without root isolation was 1.31%higher than that of gauze isolation,and 3.67%higher than that of plastic isolation.(2)In the two-year experiment without isolation,the yield of fresh faba bean and fresh maize was the highest of the three treatments.The total nitrogen content of the soil without root isolation was 4.6%higher than that of gauze isolation,and the alkali-hydrolyzed nitrogen content of soil without root isolation was 5.98%higher than that of root isolation with gauze,and 10.24%higher than that of plastic isolation.The content of available phosphorus in the soil without root isolation was 3.89%higher than that of gauze isolation,and 5.80%higher than that of plastic isolation.Sand culture experiments were conducted to study the allelopathy of faba bean extract on nutrient accumulation and photosynthesis of maize seedlings.Faba bean extracts increased nitrogen,phosphorus,and potassium contents in maize seedlings at 21 d of seedling growth.Common allelochemicals.which mainly include p-hydroxybenzoic acid,vanillic acid.coumarin acid,benzoic acid,and coumarin,were detected in the faba bean extracts.Compared with the control,the photosynthetic pigment content of maize seedlings treated with faba bean extract increased by 0.03%-7.89%,the photosynthetic rate increased by 46.97%-59.23%,the plant height increased by 1.20%-11.47%,and the fresh weight increased by 9.73%-23.89%.Through the analysis of transcriptome data,the results showed that a variety of chemicals in the extract of fresh faba bean caused changes in the transcription level of genes related to redox reaction and related enzyme activity,gibberellin biosynthesis process,amylase activity,cofactor binding,transmembrane transporter activity,organic acid metabolism.Field plot experiments were conducted to study the optimization methods of the system of fresh faba bean intercropping and fresh maize,such as sowing date,row spacing configuration and nitrogen fertilizer operation.The main results were as follow:(1)The annual yield of fresh faba bean interplanting with fresh maize increased first and then decreased with delay of maize interplanting date.Among nine treatments,the highest yield of fresh faba beans was planted in wide and narrow rows(133cm wide,67cm narrow)on April 5.In the fresh faba bean intercropping with fresh maize system,the fresh maize yield showed a downward trend with the increase of nitrogen fertilizer application,and an increasing trend with the increase of planting density.Among nine treatments,the yield of fresh maize was the highest under the treatment of 67500 plants/hm2 and the nitrogen fertilizer application rate of 225 kg/hm2,and its agronomic efficiency and apparent productivity of nitrogen fertilizer were the highest.In this study,technologies such as the replacement of inorganic nitrogen fertilizers with organic fertilizers for rice and wheat,the reduction of nitrogen fertilizer application for base tillers,and the optimization of rice straw incorporation into the field were proposed to provide technical support for reducing the input of chemical nitrogen fertilizers for rice and wheat,so as to optimize the two-cropping planting model of rice and wheat,which is conducive to promoting the green development of agriculture in Jiangsu Province.The new technologies and models proposed in this study can be popularized and applied in Jiangsu and even themiddle and lower reaches of the Yangtze River.This study has constructed a green and efficient planting model with efficient utilization of resources,significant improvement of farmland benefits combined with multi-cropping,which is beneficial to reducing non-point source pollution,protecting the ecological environment,realizing sustainable agricultural development,comprehensively promoting rural revitalization,and accelerating agriculture The development and rural modernization. |
PDF Full Text Request