Increasing the appropriate seedling density for higher yield in dry direct-seeded rice sown by a multifunctional seeder after wheatstraw return

Dry direct-seeded rice(DDR) sown using a multifunctional seeder that performs synchronous rotary tillage and sowing has received increased attention because it is highly efficient,relatively cheap,and environmentally friendly.However,this method of rice production may produce lower yields in a rice–wheat rotation system because of its poor seedling establishment.To address this problem,we performed field experiments to determine the rice yield at five seedling density levels(B1,B2,B3,B4,and B5=100,190,280,370,and 460 seedlings m-2,respectively) and clarify the physiological basis of yield formation.We selected a representative high-quality rice variety and a multifunctional seeder that used in a typical rice–wheat rotation area in 2016 and 2018.The proportion of main stem panicle increased with increasing seedling density.There was a parabolic relationship between yield and seedling density,and the maximum yield(9.34-9.47 t ha-1) was obtained under B3.The maximum yield was associated with a higher total spikelet number m-2 and greater biomass accumulation from heading to maturity.The higher total spikelet number m-2 under B3 was attributed to an increase in panicle number m-2 compared with B1 and B2.Although the panicle numbers also increased under B4 and B5,these increases were insufficient to compensate for the reduced spikelet numbers per panicle.Lower biomass,smaller leaf area,and lower N uptake per plant from the stem elongation stage to the heading stage were partially responsible for the smaller panicle size at higher seedling density levels such as B5.The higher biomass accumulation under B3 was ascribed to the increases in the photosynthetic rate of the top three leaves m-2 of land,crop growth rate,net assimilation rate,and leaf area index.Furthermore,the B3 rice population was marked by a higher grain–leaf ratio,as well as a lower export ratio and transport ratio of biomass per stem-sheath.A quadratic function predicted that 260-290 seedlings m-2 is the optimum seedling density for achieving maximum yield.Together,these results suggested that appropriately increasing the seedling density,and thereby increasing the proportion of panicles formed by the main stem,is an effective approach for obtaining a higher yield in DDR sown using a multifunctional seeder in a rice–wheat rotation system.

Several Cotton Rotation and Intercropping Systems in Cotton Planting Area of Eastern Henan Province

In recent years,the area dedicated to cotton cultivation in eastern Henan Province has experienced a continuous decline.Developing efficient multi-cropping systems for cotton and increasing the multiple cropping index represent effective strategies to stabilize the cotton planting area and enhance the income of cotton farmers.This paper presents an overview of intercropping systems and the benefits associated with cotton rotation and intercropping practices.Specifically,it discusses the"early maturing cotton-wheat"rotation system,the"cotton-watermelon"intercropping system,the"cotton-Dutch bean"intercropping system,and the"early maturing cotton-peanut-garlic"intercropping system.

Effect of Direct-seeding with Non-flooding and Wheat Residue Returning Patterns on Greenhouse Gas Emission from Rice Paddy

[Objective] This study aimed to investigate the effect of direct-seeding with non-flooding and wheat residue returning patterns on greenhouse gas emission from rice paddy. [Method] Two rice cultivars currently used in the production, Yangdao 6 （an indica） and Yangjing 4038 （a japonica）, were field grown using a direct-seeding method, and four treatments, wheat straw incorporation into soil and traditional flooding （SlF）, non-flooding and wheat straw mulching （NSM）, non-flooding and wheat straw incorporation into soil （NSl） and traditional flooding （no straw returned, Control, TF）, were imposed after sowing to maturity. Effects of direct-seeding with non-flooding and wheat residue returning patterns on CH4, N20 and CO2 emissions were investigated by using the method of static chamber-gas chromatographic tech- niques. [Result] Grain yield showed no significant difference between non-flooding and flooding treatments, but was significantly higher under the SlF than under any other treatments. The emission flux of CH4 and CO2 under TF and SlF exhibited a single peak curve, while changed little under the NSl and NSM The emission flux of N2Oshowed multiple perk curves for all the treatments. Compared with TF, SlF significantly increased mean emission flux of CH4 or N2O, decreased emission of N20, while NSl and NSM significantly decreased the mean emission flux of OH4, and increased emission flux of N2O and CO2. SIF also increased Green Warm Potential （GWP） of CH4, N2O and CO2 and the GWP per unit grain yield by 47.3%- 53.7% and 32.2%-39.4%, respectively. Both NSl and NSM decreased GWP by 24.2%-29.6% and 30.1%-35.5%, and the GWP per unit grain yield was decreased by 21.7-27.2% and 25.6%-31.1%, respectively. [Conelusion] both NSl and NSM could significantly reduce greenhouse effect of CH4, N2O and CO2 meanwhile maintain a high grain yield.

Effect of Cotton Straw Extract on Wheat Root Growth

Objective] The aim was to study the effects of cotton straw extract on wheat root growth and define the al elopathic effect of cotton straw on wheat root. [Method] A sand culture experiment was conducted under different cotton straw ex-tract levels （0%, 1.0%, 2.0%, 4.0%, 8.0% and 10.0%）, and the morphology and physiological activity of wheat （Yangmai 13） root were studied. [Result] The cotton straw extract inhibited the elongation of wheat roots, but increased the root diame-ter, resulting in the decreased root surface area and volume; The extract treatments induced the increase of root reactive oxygen species （ROS） level, which led to an increased root membrane lipid peroxidation, thereby reducing the root vigor and in-hibiting the root water uptake and formation of biomass; With the increase of con-centration of cotton straw extract, the total phenolic acid content in the extract in-creased continuously, and the total phenolic acid content was closely related to the morphogenesis and physiological activity of wheat root. [Conclusion] The cotton straw extract inhibited the morphogenesis and physiological activity of wheat root through affecting the root ROS level, and the total phenolic content was one of the main limiting factors.

Effects of plant density and mepiquat chloride application on cotton boll setting in wheat–cotton double cropping system

Sowing cotton directly after harvesting wheat in the Yangtze River Valley of China requires early mature of cotton without yield reduction.Boll-setting period synchronisation and more yield bolls distributed at the upper and middle canopy layers are also required for harvesting.The objective of this study is to quantify the individual and interaction effects of plant density and plant growth regulator mepiquat chloride(MC)on temporal and spatial distributions of yield bolls,as well as yield and yield components.During the 2013–2016 cotton growing seasons,the experiments were conducted on a shortseason cotton cultivar CRRI50 at Yangzhou University,China.Various combinations of plant density(12.0,13.5 and 15.0 plants m^(–2))and MC dose(180,270 and 360 g ha^(–1))were applied on cotton plants.The combination of 13.5 plants m^(–2)and 270 g ha^(–1)MC resulted in the greatest boll number per unit area,the highest daily boll setting number and more than 90%of bolls positioned within 45–80 cm above the ground.In conclusion,appropriate MC dose in combination of high plant density could synchronize boll-setting period and retain more bolls at the upper and middle canopy layers without yield reduction in the system of direct-seeded cotton after wheat harvest,and thus overcome the labor-intensive problem in current transplanting cropping system.

The damage risk evaluation of Aphis gossypii on wheat by host shift and fitness comparison in wheat and cotton

Aphids are considered as one of the key pests for wheat production worldwide. Major aphid species that infest wheat in China include Sitobion avenae, Rhopalosiphum padi, Schizaphis graminum and Metopolophium dirhodum. However, during our wheat field survey in Wenshang County of Shangdong＇Province, China, we observed that Aphis gossypii can feed on wheat. The damage risk of A. gossypii on wheat was assessed using host shift method. A population of A. gossypii collected from a wheat field in 2015 and another population reared on cotton under laboratory conditions for a decade without exposure to insecticides were used in the study. The results of host shift demonstrated that the A. gossypfi colony from wheat has not yet developed wheat specialization. Moreover, the assessment of A. gossypii fitness on wheat and cotton showed that fecundity and net reproductive rate of A. gossypii population fed on wheat was significantly higher comparing to the population fed on cotton, whether the initial host of A. gossypii population was wheat or cotton. This study raises a warning that the cotton aphid has potential to establish well on wheat and it may cause significant effects under specific circumstances. Therefore, future studies are required to evaluate the effects of A. gossypfi on wheat production.

棉-粮-油菜宽带轮作提升作物产量和光能利用率

棉-粮-油菜宽带轮作种植模式,能够充分利用农田资源,但种植体系内不同作物光能资源利用特性尚不明确。本研究在田间设置棉花单作(对照)、小麦-玉米一年两熟(对照)和棉花-小麦-玉米-油菜宽带轮作(以下简称“宽带轮作”) 3种种植模式,测定棉花、玉米和小麦的产量、地上部干物质重以及叶面积指数、消光系数、光能截获量等指标。结果表明,与棉花单作比较,棉花宽带轮作单位面积产量和地上部干物重分别显著增加15.20%和10.35%。与小麦-玉米一年两熟比较,玉米和小麦宽带轮作的单位面积产量分别显著增加21.61%和11.53%,玉米地上部干物质重显著增加6.17%。7月16日(盛花期)至9月13日(吐絮期),棉花宽带轮作叶面积指数比棉花单作显著增加7.21%~12.76%, 7月24日(盛花期)和8月4日(盛铃期),棉花宽带轮作光能截获率比棉花单作分别显著降低3.59%和3.24%。玉米和小麦宽带轮作的叶面积指数、消光系数和光能截获率未发生显著变化。与棉花单作、小麦-玉米一年两熟比较,棉花宽带轮作和玉米宽带轮作的全生育期光能截获量分别显著降低3.14%和显著增加0.76%,小麦宽带轮作的全生育期光能截获量未发生显著变化,棉花、玉米和小麦的光能利用率分别显著增加18.81%、6.76%和14.10%。本试验条件下,边行优势和轮作效应同时发挥作用增加了棉花、玉米和小麦的单位面积产量以及棉花和玉米的地上部干物质重,改善作物干物质的积累和分配,进而提升棉花、玉米和小麦的光能利用率。该研究明确了棉-粮-油菜宽带轮作对作物产量和冠层光能利用率的影响,可为该模式的推广应用提供理论基础。

不同种植模式对麦后复播棉花产量的影响

为缓解喀什粮棉争地矛盾,探索麦后复播棉花种植模式,开辟粮棉双丰新途径。通过设置不同种植密度及保留果枝台数二因素试验,分析不同处理对棉花花铃数、单铃质量、产量、品质的影响。研究表明:高密度A_(2)平均产量较常规密度A_(1)平均产量增加15.58%;常规密度A_(1)模式,保留不同果枝台数,产量差异不显著,高密度A_(2)模式,保留7台果枝,产量最高达2207.55 kg·hm^(-2);2种不同种植密度单铃质量均随着保留果枝台数增加而增加;高密度A_(2)(32.8965万株·hm^(-2))5行种植模式,有利于提高光和效率增加产量;麦后复播棉棉纤维成熟度不够。在喀什麦后复播棉花尚不成熟的情况下,较高的有效积温生态区、合理安排种植密度、选择麦棉两早品种、抢时播种、保留7台果枝,是提高麦后复播棉花的产量有效措施。

缩节胺运筹对夏直播棉熟相的影响

为明确缩节胺运筹对夏直播棉熟相形成的影响,2018-2019年于扬州大学实验农场以中棉425为材料,设缩节胺用量0、180、360 g·hm^(-2)3个水平,施用时期分别设盛蕾期+初花期(施用比例1∶2)、盛蕾+初花期+盛花期(施用比例1∶2∶3) 2个运筹方式,同时设常规施用方式(初花期,缩节胺120 g·hm^(-2))为对照,探讨缩节胺施用量和施用时期处理对此种植方式下熟相的调节。结果表明:缩节胺用量180 g·hm^(-2)并于盛蕾期+初花期或盛蕾+初花期+盛花期使用后再通过脱叶催熟吐絮率均能达到90%以上,且吐絮强度高,较对照显著提高46.6%~71.4%。进一步回归分析表明,黄叶率保持在9.0%~12.8%之间,主茎红茎比为52.8%~53.1%,倒1果枝红茎比为28.3%~34.3%,倒2果枝红茎比为27.5%~39.8%,倒3果枝红茎比为34.3%~8.5%,倒4果枝红茎比为49.1%~51.5%,吐絮倒序位为7.1~8.1台最有利于集中吐絮。因此,缩节胺合理运筹能形成集中吐絮的熟相,为实现机采提供技术支撑。

郭予元院士在创建中国主要粮棉作物多病虫复合群体综合防治技术体系上的学术贡献——纪念郭予元院士诞辰90周年

本文回顾了郭予元院士在20世纪80-90年代对中国主要粮棉作物多病虫复合群体综合防治技术体系研究与实践中的重要工作,包括组建粮棉作物多病虫复合群体综合防治技术体系的创新性思路、创建主要粮棉作物多病虫复合群体综合防治技术体系,以及对21世纪我国粮棉作物多病虫复合群体综合防治技术体系提出的发展前景和目标等,其中粮棉作物多病虫复合群体综合防治技术体系实施后取得了显著成效。郭予元院士在我国主要粮棉多病虫复合群体综合防治领域的相关学术思想及贡献,对我国农作物病虫害综合防治、可持续治理、绿色防控策略制定以及植物保护学科的发展产生了深远的影响,为我国实现农作物生物灾害可持续控制做出了重要贡献。

不同施氮量对秸秆还田条件下棉麦轮作生产的影响

为了研究长江流域棉区棉(Gossypium spp.)麦(Triticum aestivum L.)轮作两熟种植模式下如何降低氮肥投入而提高棉田的综合效益,试验设置了5个氮肥用量处理,分别为低氮(N1,50%N3)、少氮(N2,75%N3)、中氮(N3,棉花季和小麦单季纯氮用量分别为180.0、150.0 kg/hm2)、高氮(N4,125%N3)、富氮(N5,150%N),分析了不同施氮量对小麦和棉花的生育进程、农艺性状、产量性状及棉花纤维品质的影响,并对不同处理间的经济效益、土地利用率和生产效率进行了分析。结果表明,棉麦轮作总的生产周期在344 d左右,在长江流域棉区发展棉麦轮作是可行的;不同施氮量间小麦的有效穗、穗粒数、产量随着施氮量的增加先增加后减少,综合2年的试验结果,当氮肥水平为高氮(187.5 kg/hm2)时,小麦产量最高;不同施氮量间棉花株高、单株结铃数、子棉产量和皮棉产量差异显著,当氮肥水平为高氮(225.0 kg/hm2)时,子棉产量最高;棉麦周年生产中总产出、生产效率、净利润、收益率和产投比随施氮量的增加呈先增后减的趋势,当施肥量为高氮时值最大,总生产周期和土壤利用率随施氮量的增加而增加。

硼钼微肥浇铸作物丰产之花——追忆恩师王运华教授

基于笔者在华中农业大学从本科生到硕士研究生阶段7年的求学经历,本文回顾了与我国作物微量元素研究开拓者王运华教授相处的点滴时光,阐述了王运华教授在推动中国微量元素营养研究及应用方面所作出的卓越贡献。粮安天下,无“微”不至,王运华教授建立了中国棉花施硼以及冬小麦施钼技术体系,创建了华中农业大学微量元素研究中心和植物营养遗传学科,培养了一批微肥专业高级人才,他们中很多都成为中国植物营养教学、科研、管理、生产、经营等方面的中坚力量。王运华教授以硼和钼为切入点,用微肥联接着家国情怀和使命担当,为中国现代农业可持续发展发挥了举足轻重的作用,将永远为后辈们所学习和缅怀。

不同种植模式和灌溉方式对麦棉产量、品质及经济效益的影响

【目的】揭示种植模式和灌溉方式对冬小麦和夏棉花(以下简称麦棉)产量、品质及综合经济效益的影响,为黄河流域麦棉两熟区的种植模式和灌溉方式的科学制定提供理论依据。【方法】基于裂区设计开展大田试验,将麦棉种植模式设定为主区,主区包含麦棉套种和麦后移栽2个水平,副区为灌溉方式,包含畦灌、微喷带灌溉和地表滴灌3个水平,共6个处理。【结果】相比麦棉套种模式,麦后移栽模式能够提升冬小麦叶面积指数(LAI)和产量,提高冬小麦净收入;虽然麦后移栽模式下的棉花籽棉产量降低了5.64%,但麦棉合计净收入比麦棉套种模式提高了8.64%。相比畦灌和微喷带灌溉,地表滴灌能够显著提高麦棉株高、LAI、产量和经济效益,地表滴灌条件下的麦棉合计净收入比畦灌、微喷带灌溉分别提高36.01%和10.10%。麦后移栽和地表滴灌组合下的麦棉合计净收入最高,麦棉合计净收入最高达到15924.9元/hm^(2)。【结论】麦后移栽和地表滴灌分别是适宜于黄河流域麦棉两熟区的最佳种植模式与灌溉方式。

植保无人飞机施药防治农作物病虫害研究进展

近年来,植保无人飞机在我国迅猛发展,已成为防治农作物病虫害的重要手段。目前,植保无人飞机施药已经被广泛应用于水稻、小麦、玉米等主粮作物和以棉花为主的经济作物的病虫害防治中。本文综述分析了植保无人飞机施药对小麦赤霉病、白粉病和蚜虫,水稻纹枯病、稻瘟病和虫害,玉米螟、草地贪夜蛾和杂草以及棉花虫害的防治效果和药剂选择,简要分析了影响植保无人飞机控制效率的因素以及植保无人飞机的发展趋势。上述研究结果对植保无人飞机在作物病虫害防治中的快速发展起到了积极的推动作用。

棉花秸秆腐解特征及其对小麦产量的影响

为探讨还田的棉花秸秆腐解动态及不同还田量的棉花秸秆对小麦产量的影响,于2018-2020年冬小麦播种后,将棉花秸秆机械粉碎覆盖还田,设置全量还田(all stalk returning,AS)、半量还田(half stalk returning,HS)(移出一半秸秆后机械粉碎)、不还田(zero stalk returning,ZS)(移出全部秸秆)3个处理,分析不同还田量棉花秸秆的腐解、养分释放及其结构组分变化规律。结果显示,秸秆腐解速率表现为先快后慢,还田后20 d腐解最快,此后腐解速率逐渐下降;还田后170 d,2018-2019年半量还田和全量还田秸秆腐解率分别为73.4%和66.8%,2019-2020年分别为77.6%和60.4%。秸秆中不同结构组分的释放率存在差异,经过170 d腐解,棉花秸秆可溶性糖释放率为70.7%~81.38%,纤维素腐解率为57.3%~60.7%,木质素腐解率为44.1%~50.3%;秸秆N、P、K释放率也存在差异,N、P、K释放率分别为66.5%~74.7%、71.4%~80.5%和83.1%~87.9%。本研究结果表明,棉花秸秆还田增加了小麦有效穗数,进而提高小麦产量。可见,棉花秸秆还田有利于改善土壤养分状况,提高冬季作物(小麦)产量,其中以全量秸秆还田更好。

麦棉两熟复合根系群体对棉花根际非根际土壤酶活性和土壤养分的影响

在麦棉两熟双高产条件下,设置麦棉自然根系(根系和肥水均可相互通过)、麦棉纱网隔根(肥水可相互通过,根系不能相互通过)和麦棉塑膜隔根(根系和肥水均不能相互通过)3种套种复合根系群体,研究麦棉两熟复合根系对棉花根际和非根际土壤酶活性和土壤养分的影响。结果表明,在麦棉共生期,与麦棉塑膜隔根相比,麦棉自然根系和纱网隔根复合群体中棉花根际非根际土壤脲酶、蔗糖酶和蛋白酶的活性均有所提高,其中以麦棉纱网隔根处理的土壤酶活性最高。同时,麦棉自然根系复合群体中棉花根际非根际土壤的养分含量降低,纱网隔根处理减缓了小麦根系对棉花根系营养的竞争,同时又可能是小麦根系分泌物的作用使其养分含量最高。到棉花盛蕾期,小麦已收获,麦棉复合群体根际和非根际土壤酶活性和土壤养分状况均得到不同程度改善,其中以麦棉自然根系复合群体的改善程度最大,其土壤脲酶和蔗糖酶的活性达到最高,土壤有机质和全氮含量超过塑膜隔根,但仍低于纱网隔根。麦棉套作地下部不仅存在小麦对棉花营养竞争的不利一面,同时还存在小麦根系促进棉花根际非根际土壤酶活性和土壤养分含量提高的有利一面,且此效应将持续影响套作棉花一生。

农田残膜对土壤环境及作物生长发育的影响研究

通过盆栽模拟和大田试验研究了残膜量对土壤物理性状及不同作物生长发育的影响。结果表明，土壤中的残留地膜对土壤环境有较大影响，可使土壤容重增加、土壤水分移动速度减慢，随着残留地膜量的增加，小麦、玉米和棉花的生长发育均受到严重影响，小麦产量降低0．8％～22．1％，玉米籽粒产量降低2．1％～27．5％，棉花产量降低1％～7．5％。

麦棉套作棉花根际非根际土壤微生物和土壤养分

在麦棉套作栽培模式下,设置不隔根、纱网隔根和塑膜隔根3种麦棉套种方式,研究麦棉套作对棉花根际和非根际土壤微生物数量、活性和土壤养分(全氮、有效磷和速效钾)含量的影响,结果表明:麦棉套作有利于棉花根际与非根际土壤细菌的增殖,盛蕾期不隔根处理棉花根际土壤与非根际土壤细菌数量分别是塑膜隔根处理的2·57和2·81倍。但麦棉套作不利于土壤真菌和放线菌的增殖。细菌在土壤微生物区系中占99·9%。所以,麦棉套作显著提高了棉花土壤微生物数量,同时也增强了微生物活性。麦棉共处期纱网隔根处理棉花土壤全氮、有效磷、速效钾含量显著高于不隔根处理和塑膜隔根处理,证明麦棉套作系统中小麦根系分泌物与脱落物的存在对棉花土壤养分含量的增加有明显的促进作用,即存在种间营养补偿效应。而共处期不隔根处理套作棉土壤养分含量总体上显著低于隔根处理的现象则反映出小麦根系对棉花土壤养分的竞争作用大于其对棉花土壤养分的促进作用。小麦收获后,小麦根系对棉花养分的竞争作用解除,不隔根处理棉花土壤养分含量显著高于塑膜隔根和纱网隔根处理。

麦棉套种对棉行太阳辐射和温度的影响

对３－２式麦棉套种预留棉行的小气候效应进行研究在明，小麦对预留棉行有根强的遮荫作用；致使齐穗期预留棉行中央的光合有效辐射较冠层减少３０％，太阳总辐射削减１９％；小麦黄熟前，预留棉行内风速较一熟棉田小，午后气温也较一熟棉田低；共生前期麦套露地棉田地温较一熟棉田低，小麦黄熟后较一熟棉田高，而麦套地膜棉田的地温一直较一熟棉田高。降低小麦株高，留足预留棉行，麦套棉地膜覆盖。加强小麦生育后期的水分管理，都有利于减轻麦棉套种的不利和小气候的影响。

不同类型棉田节肢动物群落结构研究

运用群落生态学原理和方法，研究了北方平作春棉、麦套春棉和麦套夏棉节肢动物的群落结构。结果表明，平作春棉节肢动物群落组成有５５科、６８属、７３种，麦套春棉有７４科、１０２属、１０８种，麦套夏棉有５７科、８０属、８５种。平作春棉和麦套春棉间节肢动物群落的相似系数（０．６８３０）＞麦套春棉和麦套夏棉（０．５５９８）＞平作春棉和麦套夏棉（０．４１２５）。麦套春棉的多样性指数和均匀度值分别为１．３４８６和０．２８８４＞麦套夏棉（分别为１．２８３９和０．２８６８）＞平作春棉（分别为０．６０６１和０．１４０４）；优势度值则为平作春棉（０．７７６１）＞麦套夏棉（０．５６７６）＞麦套春棉（０．４９７１）。麦套棉（特别是麦套春棉）节肢动物群落的结构较平作棉稳定，对环境的变化或来自群落内部种群波动的缓冲作用较强，是不利于某些害虫发生，而有利于天敌繁衍的良好生态系统。