作物茬口对缓解大豆连作危害效果的研究

研究了苜蓿、玉米和大豆3种茬口对缓解连作大豆危害的效果。结果表明:苜蓿茬连作2 a和3 a大豆产量比玉米茬连作2 a和3 a大豆产量分别增加8.4%、6.6%,比3 a和4 a连作大豆产量分别极显著增加26.7%和27.5%;玉米茬连作2 a和3 a大豆产量比3 a和4 a连作大豆产量分别增加16.9%和19.6%,差异极显著。与3 a连作大豆相比,苜蓿茬和玉米茬连作2 a大豆的株高分别极显著增加19.5 cm和13.8 cm;苜蓿茬的单株粒重比玉米茬和3a连作大豆处理增加3.6 g和4.3 g,差异极显著。与4 a连作大豆相比,苜蓿茬和玉米茬连作3 a大豆的株高分别增加23.7 cm和17.1 cm,差异极显著,苜蓿茬比玉米茬上连作3 a大豆株高显著高6.6 cm;苜蓿茬比玉米茬和4 a连作大豆处理单株粒重增加2.1 g和7.8 g,玉米茬比4 a连作大豆处理单株粒重增加5.7 g,差异均极显著。可见,苜蓿茬口对缓解大豆连作危害优于玉米茬口和大豆茬口。     

Reduced inter-row distance improves yield and competition against weeds in a semi-dwarf durum wheat variety

Weed and nutrient management in cropping systems of semi-arid areas is a major constraint to cereal yield. Where the use of herbicides is banned or discouraged, the competitive ability of a crop is crucial to reduce weed growth and diffusion. Genotypic differences in the competitive abilities of crops are an important trait to reduce weeds, especially for plant height. However, there is contrasting information about the interactions of other management practices and genotypic traits on wheat yield and competitive ability against weeds and weed growth. The present study investigated yield and quality of durum wheat (Triticum durum Desf.) and weed growth and composition for two wheat cultivars with contrasting competitive abilities against weeds. Wheat was grown under three spatial arrangements (5-cm, 15-cm, 25-cm inter-row distance) and three sowing densities, and broadleaf weeds were either removed or not. The sowing rate did not affect the yield of these wheat cultivars or the weed growth. Reduced inter-row distance dramatically reduced weed biomass for both wheat cultivars, and increased wheat yield and nitrogen uptake in the low-competitive, high-yielding, semi-dwarf cv. ‘PR22D89’, when both weed free and with weeds. These results have direct implications for weed and nutrient management in low-input and organic cropping systems.     

带状种植系统养分供给与利用研究进展

带状种植是1种以固N植物篱为核心、农作物与植物篱相间种植的农林复合经营模式，植物篱通过修剪避免对农作物遮光，其枝叶作为覆盖物和有机肥，可提高土壤肥力。阐述了植物篱枝叶N素矿化和利用、枝叶有机碳矿化及其对土壤有机质的影响以及固N植物篱对土壤P素和其他矿质元素的供给状况，并评价了该模式下土壤养分和有机质动态。     

基于区块链中继技术的集群式农产品供应链溯源模型

集群式农产品供应链具有链条长且多、生产分散、信息多源异构、网链结构复杂等特点。面向集群式农产品供应链区块链溯源的需求,多链式区块链比单链式区块链更具有优势。但多个区块链相互独立使得不同链上的数据相互隔离,导致不同联盟在多链式区块链网络中数据断裂,无法构成完整的溯源链条,该研究提出一种基于区块链中继技术的集群式农产品供应链溯源模型,打通联盟间的信息孤岛,实现整个供应链的信息贯通。分析集群式农产品供应链的业务构成,利用区块链中继技术打通供应链上下游区块链,构造集群式农产品供应链的中继多链拓扑结构和溯源模型;应用链借助中继链和跨链路由实现跨链交互,并通过Hyperledger Fabric背书策略检验跨链交易的有效性。最后,以集群式猕猴桃供应链为例,设计和实现了该模型的原型系统,并进行了功能、性能和扩展性的测试与分析。结果表明：在功能方面,该模型可以保证跨链溯源信息的完整性、可信性和有效性,能够有效解决多链式区块链溯源中的信息断链问题;在性能方面,系统数据写入的吞吐量最高为561.8（事务数/s,transactions/s）,高于单链式区块链的118.1 transactions/s;数据写入时延均值为1.49 s,优于单链式区块链的数据写入时延均值5.92 s;在扩展性方面,系统中链的数量能够按照业务需求动态增加,灵活应对集群式供应链变化。该模型能实现集群式农产品供应链溯源,研究结果对区块链溯源网络的扩大和实现行业性的统一布局、协同发展有一定意义。     

沿江稻区多元多熟种植模式及其高效技术途径研究

针对市场经济日益发达、人地矛盾不断加剧、产品需求日趋多样的现实 ,结合长江下游沿江农区的生态特征和资源特点 ,研究并提出了沿江稻区种植业实行粮饲经菜多元多熟结构的优化途径。开发出粮饲肥、粮饲果、粮饲菜、稻田超高效等类型的多元多熟种植模式。与此同时 ,研究了与多元多熟种植模式相配套的高产高效关键技术。     

Study on the Yield Reduction Mechanism of Soybean Planted under Continuous and every Second Year Cropping Conditions

Three-year investigation was conducted to demonstrate the mcchanism of reduction of soybean yield aroused by continuous and every second year cropping.Compared to normal cropping,there are many unfavorable changes in some major elements of soybean plant and soil environmeng.Chloropyll content was .Phosphorous content of soybean plant was decreased seriously.Potassium content was lower while calcium content was higher.Magnesim content was wot affected and decreased in susceptive varieties.Some deseases and insects of soybean under continuous and very second year cropping conditions became serious as continuous years prolonged.Organic matter content tended to go down from normal rotation to continuous cropping .Amount of bacteria and antinomyces decreased while amount of fungi increased.The evelopment of symbiotic nitrogen fixation system was deteriorated.     

Adaptive relay selection algorithm in decode-and-forward cooperative communication networks

An adaptive relay selection algorithm(ARS) is proposed to optimize the performance of decode-and-forward cooperative communication networks, both system outage probability and average numbers of cooperative relays are analyzed. When the direct transmission between source and destination is fail, according to the channel quality, the destination orders relay nodes in the decode set, and the ordered relays are included in cooperation in turn until the instantaneous received SNR at destination is not smaller than the preset SNR threshold. Simulation results show that, the proposed algorithm can get optimal outage performance, decrease the average numbers of cooperative relays efficiently, to incrense bandwidth efficiency and reduce system overhead.     

Study on Economic and Ecological Environment Effects of Ecological Cropping Patterns in Small Watershed

在三峡库区典型紫色土坡耕地,设置了四种生态种植模式,进行经济和生态环境效应的研究。结果表明:投入产出比,梨×连翘/花生>桃×连翘/花生>桃/花生>梨/花生>CK,其中梨×连翘/花生与桃×连翘/花生模式分别比对照提高69.9%和65.5%,;影响果树冠幅的主要因子是土层厚度、坡位与种植模式;套种连翘的二种模式须根量明显比其它模式高,树种根系分布特征、种植密度和土层厚度是影响须根量的主要因素;种植模式和坡位均显著影响土壤孔隙度的发育,各种植模式的土壤孔隙度顺序:梨×连翘/花生>桃×连翘/花生>桃/花生>梨/花生>CK,随坡位的升高土壤孔隙度呈降低的趋势;各生态种植模式土壤肥力均比对照有所提高,乔、灌、草结合是一种较好的维持土壤肥力模式。结合生态、经济指标,三峡库区紫色土丘陵区可推广梨×连翘/花生模式与桃×连翘/花生两种模式。     

湖北双季稻区免耕直播油菜生长及产量形成

长江流域双季稻区因茬口紧、土壤黏重,晚稻收获后大都未种植下茬作物而形成冬闲田。本研究以华双5号油菜品种为材料,在湖北双季稻区三试验点进行裂区试验,测定油菜各生育期在不同氮素及密度水平下的个体及群体指标,成熟期考察经济性状及产量构成,为双季稻区免耕直播油菜示范及管理提供依据。结果表明：(1)双季稻区免耕直播油菜全生育期尤其是苗期显著缩短,苗期生长量严重不足,蕾薹期至开花期油菜生长快,春发特性明显;(2)氮肥及种植密度水平对双季稻区免耕直播油菜生长及产量有着显著影响,增施氮肥可改善个体素质、增加产量,提高密度可提高群体素质、增加产量;(3)湖北各试点每公顷纯氮用量270 kg、种植密度为45万株及60万株处理的产量均接近或达到2 250 kg hm^–2,超湖北平均单产,说明油菜免耕直播栽培模式可在湖北双季稻区试验示范;(4)生产实践中,应重视氮肥与密度的双重调节,以肥促长、以密补迟,相互配合。     

作物连做障碍中酚酸类物质的生物降解研究

为了有效解决作物连做障碍中酚酸类物质的危害问题,探索了黄孢原毛平革菌所分泌的胞外酶系对酚酸类物质香草酸、阿魏酸和对羟基苯甲酸的降解功能。选用黄孢原毛平革菌(P.chrysosporium)与香草酸、阿魏酸、对羟基苯甲酸等酚酸类物质共同培养3天后,用高效液相色谱技术检测其含量。结果表明,3种酚酸平均降解率分别为98.39%、97.88%和58.20%,其降解效果均达极其显著水平。该研究结果,将为今后在农业生产中有效利用该菌进行农作物连做障碍治理和改善土壤环境,提供了理论依据。