Multivariate Analysis, Description, and Ecological Interpretation of Weed Vegetation in the Summer Crop Fields of Anhui Province, China

Two surveys were conducted to investigate weed vegetation in a 153-hm^2 sampling area of summer crop fields from Anhui Province, China, through visual scoring of the level of weed infestation compared with summer crops on a seven-class scale. In total, 155 sampling sites were selected in the field based on crops, tillage, rotation systems, geographical regions, and soil types across the province. Data on weed communities and environmental factors were collected and analyzed through principal component analysis （PCA） and canonical correspondence analysis （CCA）, and the output was interpreted ecologically. Results showed that the main factors influencing the structure and distribution of weed communities in summer crop fields were the soil submersion period, latitude, and soil type and pH. The CCA indicated a significant relationship between weed dominance and soil submersion duration, latitude, and soil pH. From the result of the PCA and CCA ordination, the 155 sampling sites could be divided into three groups based on geographic and floristic composition, as well as weed abundance. The southern dry land group, which was characterized by a double-cropping system in the hilly regions of southern and central Anhui Province with a continuous summer crop and an autumn dry land crop, was dominated by Galium aparine Linn. var. tenerum （Gren. et Godr） Robb., Avenafatua L., and Veronica persica Poir. The northern dry land group, which had the same cropping system as the southern dry land group, was dominated by G. aparine var. tenerum, Galium tricorne Stokes, Descurainia sophia （L.） Schur., and Lithospermum arvense L. in the North Anhui Province, China. These two dry land groups could be combined into one large dry land group, in which the Galium weed vegetation type dominated. The third group was the paddy soil group, which was characterized by a continu- ous summer crop and double- or triple-cropping systems of rice, and prevailed in the south and central areas of Anhui Province; Alopecurus aequalis Sobol. was the dominant weed in this group. Other main weeds in this group included Malachium aquaticum （L.） Fries, Stellaria alsine Grimm, Alopecurusjaponicus Steud., and Lapsana apogonoides Maxim. Thus, the weed community distributions in this group were described as the Alopecurus weed vegetation type. The paddy soil group could be divided into two subgroups, one southern and one central paddy soil subgroup. A strategy for integrated weed management is suggested according to the weed distribution pattern. The present study serves as a good example of how a quantitative research method was used to associate a visual estimate of weed infestation with multivariate analyses, such as PCA and CCA, and how this method can be applied to the study of weed vegetation on arable land.

Observed Climatic Variations in the Growing Season of Field Crops in Northeast China from 1992 to 2012

To determine the potential effects of climate change on crop phenological development and productivity, an integrated analysis was conducted based on the observed climatic and phenological records of Northeast China from 1992 to 2012. A set of quality assurance procedures, including repeated record checks, agro-meteorological station selection, internal consistency checks, temporal outlier checks, spatial outlier checks, and interpolation of missing data, were designed and applied to the phenology datasets of spring maize and paddy rice. Our results indicated that almost all phenological dates of spring maize and paddy rice became increasingly delayed from 1992 to 2012, The duration of the growing season was prolonged, particularly for the grain-filling stage （GS3）. The prolonged growing season was beneficial to productivity. For spring maize, the average precipitation during GS3 decreased at a rate of 27.46 mm/decade, and the annual accumulated temperature over 10℃ increased at a rate of 31.07℃/ decade. Farmers initiatively adjusted crop cultivars and selected drought-resistant crops to cope with the challenges of drought.

Field water surplus and deficit of major crops in dryland of northern China

The definition and classification of field evapotranspiration was discussed, based on which the calculation model for field evapotranspiration was established. Based on crop, soil measurements and mean climatic data in 1950-1980, mean field water surplus or deficit on climatic, crop and cropland basis in dryland of northern China was calculated, and the pattern of field water surplus or deficit was analyzed and discussed in this paper.

Study of Dynamics of Floodwater Nitrogen and Regulation of Its Runoff Loss in Paddy Field-Based Two-Cropping Rice with Urea and Controlled Release Nitrogen Fertilizer Application

The article deals with the effects of urea and controlled release nitrogen fertilizer （CRNF） on dynamics of pH, electronic conductivity （EC）, total nitrogen （TN）, NH4^＋-N and NO3 -N in floodwater, and the regulation of runoff TN loss from paddy field-based two-cropping rice in Dongting Lake, China, and probes the best fertilization management for controlling N loss. Studies were conducted through modeling alluvial sandy loamy paddy soil （ASP） and purple calcareous clayey paddy soil （PCP） using lysimeter, following the sequence of the soil profiles identified by investigating soil profile. After application of urea in paddy field-based two-cropping rice, TN and NHa＋-N concentrations in floodwater reached peak on the 1st and the 3rd day, respectively, and then decreased rapidly over time; all the floodwater NO3--N concentrations were very low; the pH of floodwater gradually rose in case of early rice within 15 d （late rice within 3 d） after application of urea, and EC remained consistent with the dynamics of NH4^＋-N. The applied CRNF, especially 70% CRNF, led to significantly lower floodwater TN and NH4^＋ concentrations, pH, and EC values compared with urea within 15 d after application. The monitoring result for N loss due to natural rainfall runoff indicated that the amount of TN lost in runoff from paddy field- based two-cropping rice with urea application in Dongting Lake area was 7.47 kg ha^-1, which accounted for 2.49% of urea- N applied, and that with CRNF and 70% CRNF application decreased 24.5 and 27.2% compared with urea application, respectively. The two runoff events, which occurred within 20 d after application, contributed significantly to TN loss from paddy field. TN loss due to the two runoffs in urea, CRNF, and 70% CRNF treatments accounted for 72, 70, and 58% of the total TN loss due to runoff over the whole rice growth season, respectively. And the TN loss in these two CRNF treatments due to the first run-off event at the 10th day after application to early rice decreased 44.9 and 44.2% compared with urea, respectively. In conclusion, the 15-d period after application of urea was the critical time during which N loss occurred due to high floodwater N concentrations. But CRNF decreased N concentrations greatly in floodwater and runoff water during this period. As a result, it obviously reduced TN loss in runoff over the whole rice growth season.

Field Efficacy Trial and Optimum Control Period of Rice False Smut(Ustilaginoidea virens) in Single Cropping Middle-late Rice

[Objective]The paper was to study optimum chemical agents and control periods against rice false smut( Ustilaginoidea virens) in single cropping middle-late rice. [Method]Taking chemical agents( triadimefon,armure,Jinggangmycin) as main treatments and spraying periods( within 7 d before initial heading stage,within 7 d before initial heading stage + initial heading stage,initial heading stage) as assisted treatments,the field efficacy trial and optimum control period of U. virens in single cropping middle-late rice were studied using Huanghuazhan and Jinnongsimiao as experimental materials in 2013. [Result] Three chemical agents,triadimefon,armure,Jinggangmycin,extremely reduced diseased panicle rate and disease index of U. virens,but there was no significant difference among three chemical agents. Spraying period did not have significant impact on diseased panicle rate and disease index of U. virens,whereas spraying within7 d before initial heading stage and during initial heading stage had relatively good control effect. Yield increased significantly after application of three chemical agents,and armure led to greater increase. The reason for yield increase was that seed setting rate was significantly increased,and the number of filled grains per panicle was significantly increased. Although spraying period influenced yield,the difference was not significant. [Conclusion] Triadimefon,armure and Jinggangmycin had good control effects against U. virens in single cropping middle-late rice,of which armure had better control effects. Spraying chemical agents increased seed setting rate,and further increased the number of filled grains per panicle and yield. Spraying within 7 d before initial heading stage and during initial heading stage had relatively better control effect against U. virens.

Chemical Weeding in Dry Direct Seeding Fields of Single Cropping Middlelate Rice

Chemical weeding in dry direct seeding fields of single cropping middle-late rice was studied in Huida vegetable farm of Huizhou City in 2012. The main treatment was herbicide（ pretilachlor ＋ bensulfuron-methyl,Yangguo and butachlor）,and the sub-treatment was application method（ soil treatments,seedling treatment and integrated treatment）. The results showed that 80 g pretilachlor ＋ bensulfuron-methyl（ 36% pretilachlor ＋ 4% bensulfuron-methyl） diluted with 50 kg water could be sprayed or 200 g Yangguo（ 23. 9% butachlor ＋ 1. 1% bensulfuron-methyl） mixed with 15 kg sandy soil could be broadcasted per 667 m2 on the sowing day or the second day under moist condition of soil,which could effectively control weeds in dry direct seeding fields of single cropping middle-late rice.

Genetic Engineering of Field, Industrial and Pharmaceutical Crops

Ability to modify plants at the genomic level by advanced molecular technology has enhanced the scope of improvements in plant traits attempted earlier through conventional breeding methods. Techniques such as genetic transformation have opened new vistas whereby functional genes, not commonly present in a particular species can be added from other species. The traits incorporated into the genetically engineered plants in the beginning were confined to those governed by dominant genes, e.g. insecticide resistance and herbicide tolerance but advancements with time now also permit the transfer of complexly inherited traits such as drought and cold tolerance. Transgenic technology is also useful in understanding gene expression and metabolic pathways which can then be used to harness the full genomic potential of the plant. This review presents a narrative on development of transgenics and their use for the improvement of field, industrial and pharmaceuticals crops. In addition, discussions are made on current status on genetically modified crops, hurdles to genetic engineering, overcoming strategies and future scope.

Study on a new grain-cash cropping pattern in paddy field

We studied a new grain-cash cropping pattern composed of "barley/watermelon + waize-rice", comparing with "barley / watermelon-rice" (CKI), "watermelon-rice", (CK2). The experiment was conducted in CNRRI’s field for 3 yr, employing completely randomized design with three replications, and each plot occupied 207 m~2. The soil in the experiment field contained: N, 2.48 g. kg, quick effective P 4 mg. kg, and quick effective K 53 mg·kg. The varieties tested were Zhemai 2 (barley), Zhemi 1 (watermelon), Suyu 1 (maize), and Shanyou 63 (hybrid rice).

新农科建设背景下作物栽培学课程教学改革研究

在新农科建设背景下,现代农业发展对涉农专业人才提出了更高的要求,而课程教学是人才培养的重要内容。本文以作物栽培学课程为研究对象,从思政元素、教学内容、教学方法和考核体系4个方面对该课程教学现状进行研究,并提出对应的优化改进建议,具体包括挖掘思政元素,更新教学内容,改进教学方法,以及建立多元考核体系。目的在于为新农科背景下涉农高校作物栽培学课程的教学改革研究提供参考,提升新农科人才培养质量。

作物轮作对多年连作棉田土壤细菌群落结构的影响

新疆棉田连作问题突出,作物轮作是缓解棉田连作障碍的有效措施。通过对长年连作棉田轮作苜蓿、大豆、花生等六种作物后土壤进行细菌群落结构分析,评价六种作物对棉田土壤微生态的影响程度,筛选能够显著改善提升连作棉田土壤微生态的作物。结果表明:大豆、花生、苜蓿三种豆科作物根际的土壤细菌群落结构与棉花相似性较高,对棉田土壤细菌ACE指数、Chao1指数虽有提升但无显著差异。而番茄、玉米、甜菜三种作物对棉田土壤细菌群落结构影响较大,显著降低了棉田土壤细菌Alpha多样性及不同分类水平细菌种群的数量。在物种组成方面,变形菌门(Proteobacteria)、放线菌门(Actinobacteria)和酸杆菌门(Acidobacteria)为土壤中优势细菌门,变形菌门在番茄根际土壤的丰度最高(58.4%),在苜蓿根际最低(40.5%);放线菌门在苜蓿根际丰度最高(15.8%),在番茄根际最低(6.5%);酸杆菌门在大豆根际丰度最高(10.2%),在番茄根际最低(5.5%)。土壤中显著差异细菌种群主要富集在苜蓿、大豆根际,但是不同作物单季轮作未对土壤中主要有益细菌种群的相对丰度产生显著影响。综合看,大豆、花生、苜蓿三种豆科作物单季轮作对棉田土壤细菌群落结构的影响较小;番茄、玉米和甜菜能够显著降低棉田土壤细菌多样性和种群数量,其中甜菜的影响作用最显著。

Multiple cropping and soil fertility in sustainable production of paddy fields

Multiple cropping has been popularized on morethan two thirds of the total area of paddy fields inSouth China.It demands more nutrients due tohigher cropping index.Therefore,how to keepmoderately higher yields of multiple crops and to

农作物秸秆禁烧政策执行阻滞及其破解:一个力场分析框架

基于W市X镇的实践个案,从“力场”理论视角出发,构建一个“压力-阻力-动力-引力”PRMA力场分析框架,以解析农作物秸秆禁烧政策执行阻滞问题。结果表明:力场视角对基层政策执行更具解释力;上级政府部门压力、农户阻力与执行机构动力、政策环境引力之间形成“力差”,是政策执行陷入阻滞的原因,且影响镇村干部的执行策略选择;破解农作物秸秆禁烧政策执行阻滞,应从减压力、降阻力、增动力、扩引力等4个方面改变原有的“阻碍力>推动力”的“力差”格局,形成力场内“推动力>阻碍力”的常态化格局。据此,建议地方政府构建常态化治理机制,同时通过增进地方政策目标的科学化与完善考核机制以减轻压力、完善配套政策以扩大引力、多元利益激励以降低目标群体阻力、扩权赋能和建立激励机制以增强执行动力。

基于神经辐射场的苗期作物三维建模和表型参数获取

苗期作物三维结构的精准高效重建是获取表型信息的重要基础。传统的三维重建大多基于运动恢复结构-多视图立体视觉(Structure from motion and multi-view stereo,SFM-MVS)算法,计算成本高,难以满足快速获取表型参数的需求。本研究提出一种基于神经辐射场(Neural radiance fields,NeRF)的苗期作物三维建模和表型参数获取系统,利用手机获取不同视角下的RGB影像,通过NeRF算法完成三维模型的构建。在此基础上,利用点云库(Point cloud library,PCL)中的直线拟合和区域生长等算法自动分割植株,并采用距离最值遍历、圆拟合和三角面片化等算法实现了精准测量植株的株高、茎粗和叶面积等表型参数。为评估该方法的重建效率和表型参数测量精度,本研究分别选取辣椒、番茄、草莓和绿萝的苗期植株作为试验对象,对比NeRF算法与SFM-MVS算法的重建结果。结果表明,以SFM-MVS方法重建点云为基准,NeRF方法重建的各植株点云点对距离均方根误差仅为0.128~0.395 cm,两者重建质量较接近,但在重建速度方面,本文研究方法相比于SFM-MVS方法平均重建速度提高700%。此外,该方法提取辣椒苗株高、茎粗决定系数(R^(2))分别为0.971和0.907,均方根误差(RMSE)分别为0.86 cm和0.017 cm,对各苗期植株叶面积提取的R^(2)为0.909~0.935,RMSE为0.75~3.22 cm^(2),具有较高的测量精度。本研究提出的方法可以显著提高三维重建和表型参数获取效率,从而为作物育种选苗提供更为高效的技术手段。

旱区连作砂田土壤质量和土地生产力演变与调控研究进展

砾石覆盖在改变旱区水文循环和物质转化方面有着至关重要的作用。然而,长期连作给砂田土壤质量及土地生产力带来危机和不确定性。以连作砂田为研究对象,归纳总结了连作年限对砂层质地结构、土壤物理结构、土壤水盐热效应、土壤养分状况、土壤酶活性、土壤微生物特性、作物生长发育以及产量品质的影响效应和可能机制,发现砂田土壤生态环境和土地生产力在人类活动及自然侵蚀的扰动和破坏下整体呈现退化态势,但对不同覆盖条件、施肥水平和种植结构等农田管理措施的响应过程表现出差异性。继而,基于土壤质量和土地生产力的协同和互作效应深入揭示了砂田性能逐年退化机理,并简述了生物、农业及工程调控措施在砂田退化阻控和修复方面的应用进展。在此基础上,提出了砂田退化进程中急需解决的关键科学问题和未来发展方向,主要包括土壤质量演变的基本过程及其发生机制、“砾石-土壤-微生物-植物”系统的叠加和互作效应及其分子机理、土壤改良与生物防治措施的定量化及其调控机制三个方面。在气候变化、植被演替和土地退化背景下,废弃风化砾石的劣化增肥机制及其环境效应将是今后研究的重点。

覆土种植杏鲍菇营养评价与效益分析

以工厂化种植杏鲍菇为对照,检测覆土种植不同采收期杏鲍菇的蛋白质、氨基酸、脂肪等营养成分和种植前后土壤养分含量,根据覆土种植投入产出计算效益,探讨冬闲田杏鲍菇覆土种植-菌渣还田-粮食/水果/蔬菜轮作种植模式的可行性。结果表明,不同采收期覆土种植杏鲍菇鲜品子实体蛋白质、脂肪、氨基酸等含量均高于工厂化种植,采收期对覆土种植杏鲍菇蛋白质含量影响较大,成熟初期含量最高,达4.19 g/100 g,是成熟期的1.3倍、孢子释放期的1.6倍、工厂化种植的1.9倍。覆土种植杏鲍菇必需氨基酸、呈味氨基酸含量均高于工厂化种植,E/T值接近FAO/WHO提出的优质蛋白质氨基酸组成值。菌渣还田后土壤有机质含量提高了116%,杏鲍菇从覆土到采收完毕共34 d,生物转化率可达136%,投入产出比达1:1.8。冬闲田覆土种植杏鲍菇子实体营养丰富,味道鲜美,经济效益好,菌渣还田可提高土壤有机质含量,适合在南方水稻主产区、荔枝等果园的林下冬春季推广应用。

二氯异噁草酮应用于作物田杂草防除谱测定

为明确二氯异噁草酮应用于作物田防除杂草的防除谱,在温室内采用盆栽法测定了36%二氯异噁草酮悬浮剂对冬季作物田和夏季作物田的除草活性。冬季作物田杂草防除谱测定结果显示,二氯异噁草酮对小麦田多花黑麦草和日本看麦娘均有较好的防除效果,其GR_(50)分别为39.89、35.11 g(a.i.)/hm^(2),GR_(90)分别为105.88、104.54 g(a.i.)/hm^(2),对雀麦也有较好的效果,但对另两种禾本科杂草菵草和节节麦防效差;该药剂对冬季作物田阔叶杂草播娘蒿、荠菜、猪殃殃、麦家公效果均优,明显好于对禾本科杂草的效果,其中对播娘蒿和荠菜的防除效果最好,其GR_(50)分别为4.86、4.69 g(a.i.)/hm^(2)之间,GR_(90)分别为25.54、17.36 g(a.i.)/hm^(2);对猪殃殃、麦家公的GR_(50)分别为15.77、22.25 g(a.i.)/hm^(2)之间,GR_(90)分别为38.58、53.10 g(a.i.)/hm^(2),但对另一种阔叶杂草泽漆的防效较差。夏季作物田杂草防除谱测定结果显示,二氯异噁草酮土壤封闭处理对夏季作物田禾本科杂草马唐、稗草、牛筋草、狗尾草和虎尾草效果均较好,其中对马唐、稗草、牛筋草、狗尾草的GR_(50)在12.33~27.00 g(a.i.)/hm^(2)之间,GR_(90)在27.40~59.38 g(a.i.)/hm^(2)之间,对夏季作物田阔叶杂草整体效果差,供试杂草中只有马齿苋效果较好,其GR_(50)和GR_(90)分别为33.33、52.82 g(a.i.)/hm^(2),对饭包草、反枝苋、马泡瓜和铁苋菜效果均差。试验结果表明,二氯异噁草酮对冬季作物田杂草和夏季作物田杂草,均有自己的杂草防除谱,田间应用时应根据田间草相,选择合理药剂进行复配。

稻萍共生对水稻磷素吸收和磷肥利用效率的影响

稻萍共生是我国传统的稻作方式,能提高水稻产量和氮肥利用效率,然而目前还鲜有研究关注稻萍共生对水稻磷肥利用效率的影响。通过田间试验,探讨稻萍共生处理对稻田土壤理化性质、水稻产量和磷肥利用效率的影响。结果表明:稻萍共生处理未显著改变土壤有机质、总氮、总磷和有效磷含量,但显著提高土壤硝态氮含量(P<0.05)。稻萍共生促进了水稻的磷吸收,显著增加了籽粒磷吸收量(P<0.05)和地上部总磷吸收量(P<0.05)。此外,稻萍共生还提高了水稻的磷肥回收利用率(P<0.05),说明稻萍共生处理能有效提高水稻磷肥利用效率,为水稻磷肥的高效利用提供了参考途径。

填闲作物还田方式对烟田土壤轻重组有机碳的影响

为了提高多年连作烟田的土壤肥力,改善土壤生态环境,在烤烟冬闲期种植油菜、冬牧70、光叶紫花苕等3种作物,同时以冬季空闲不种植任何作物为对照,采取2种方式(掩青和收割)进行处理,通过测定不同处理不同土层的土壤轻、重组有机碳含量、比例及储量,探讨填闲作物收割和掩青处理对烟田土壤轻重组有机碳的影响。结果表明,不同填闲作物和不同还田方式下土壤总有机碳、重组有机碳、轻组有机碳含量均随着土壤深度的增加而降低。与对照相比,填闲作物掩青处理能够显著增加土壤总有机碳、重组有机碳、轻组有机碳含量,尤其是冬牧70在20~40 cm土层增加比较显著,分别增加了22.3%、21.98%、27.78%;填闲作物收割处理会降低土壤轻组有机碳比例和土壤轻组有机碳储量,而掩青处理则会增加土壤轻组有机碳比例和轻组有机碳储量,其中冬牧70掩青在0~20 cm土层增加比较明显,分别增加了18.14%、40.03%。填闲作物掩青处理增加了烟田土壤的含水量和持水量、降低了土壤容重以及增加土壤轻重组有机碳储量。综合来看,冬牧70掩青处理效果最好,能显著增加土壤总有机碳和轻重组有机碳含量,油菜次之。

稻秆炭还田对红壤双季稻田土壤碳氮磷钾生态化学计量学特征及其综合肥力的影响

为探究稻秆炭对红壤双季稻田土壤碳氮磷钾生态化学计量学特征及其综合肥力的影响,本研究采用大田定位试验,设置不施氮肥和生物炭(CK)、单施稻秆生物炭(B)、100%氮肥(N_(100))和100%氮肥+稻秆生物炭(N_(100)B)4个处理,分析不同处理稻田土壤碳、氮、磷、钾生态化学计量学特征及其综合肥力的变化情况。结果表明,与CK相比,B和N_(100)B处理土壤pH值分别提高0.05和0.13个单位。与N_(100)相比,N_(100)B处理不仅使土壤有机质、全氮、NO_(3)^(-)、NH_(4)^(+)、微生物生物量碳和氮含量增加5.13%、3.47%、11.7%、14.91%、60.89%、30.75%,还使土壤C/N、C/P、C/K、N/P、N/K化学计量比提升1.88%、2.10%、2.84%、3.62%、5.41%,并提升土壤综合肥力指数(IFI)2.97%。综上,稻秆炭还田有利于改善双季稻田土壤碳氮磷钾生态化学计量学特征及其综合肥力。本研究结果为合理高效利用南方红壤双季稻区稻秆资源提供了实践指导。

基于ESP32的大田水肥一体化控制系统设计

为解决在传统大田作物种植过程中的水肥一体化集成度低、成本高、远程监控与管理困难的问题,设计一个能够远程控制的水肥一体化控制系统。该系统包含主控模块、数据采集模块、执行装置模块和远程控制模块,实现了对水肥一体化的全面控制。通过数据采集模块获取EC值、肥液流量等数据,主控模块主要进行智能化分析,通过执行装置模块实现对水肥的自动施用,再使用远程控制模块对数据进行存储,并允许用户通过远程方式监控和调整系统工作状态。经测试,该系统在本地控制时响应耗时平均为16.5 ms,远程控制响应平均耗时为1290 ms,远程控制与本地控制所显示的系统工作状态以及传感器数据实时同步。该系统设计为大田作物水肥一体化管理提供了一种先进、高效的解决方案,提高了水肥一体化的集成度,降低了成本,并解决了远程监控难题。