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.

Evaluation of Harvest Aid Chemicals for the Cotton-Winter Wheat Double Cropping System

Timing of harvest is critical for mechanical picking in cotton production, especially in those regions with double cropping system. Appropriate and safe harvest aids will improve timing and facilitate harvest of cotton in the double cropping system. Three defoliants （dimethipin, thidiazuron, and thidiazuron-diuron） and one boll opener （ethephon） were included in this research. They were evaluated for their effects on defoliation, boll opening, seedcotton yield, seed quality, and fiber quality of field grown cotton when used alone or as a mixture in 2009 and 2010. Defoliation and/or boll opening were increased by all three defoliants and ethephon, especially by mixtures of a defoliant and ethephon. First harvest of seedcotton was significantly increased with defoliant-ethephon mixtures. No significant adverse effects were observed on boll weight, lint percentage, seed quality, and fiber properties. It was estimated that tank mixes of ethephon and one of the three defoliants can improve the adjusted gross revenue. Boll opening can be used as an alternative indicator for the adjusted gross revenue, because, it was linearly and positively correlated with the relative adjusted gross revenue and convenient in measurements. Wheat seedling growth was not affected by thidiazuron, whereas its seedling emergence, root dry weight, relative water content, and electrolyte leakage were adversely affected by dimethipin and thidiazuron- diuron when concentration was above 340 and 100 g （a.i.） ha-1, respectively. 90% defoliation and 80% boll opening were observed with the high rate of thidiazuron-ethephon mixture, but no adverse effects on winter wheat. The results suggested that tank mixes of ethephon with thidiazuron can be used effectively and safely in the cotton-winter wheat double cropping system to improve yield without adverse effects on seed quality and fiber quality.

Exploring the Potential of Cowpea-Wheat Double Cropping in the Semi-Arid Region of the Southern United States Using the DSSAT Crop Model

Information is limited on the potential of double-cropping cowpea (Vigna unguiculata L.) and wheat (Triticum aestivum L.) in the semiarid region of the southern United States. Using the Decision Support System for Agrotechnology Transfer (DSSAT) crop model and weather data of 80 years, we assessed the possibility of cowpea-wheat double-cropping in this region for grain purpose as affected by planting date and N application rate. Results showed that the possibility of double-cropping varied from 0% to 65%, depending on the cropping system. The possibility was less with systems comprising earlier planting dates of wheat and later planting dates of cowpea. Results indicated that cowpea-wheat double-cropping could be beneficial only when no N was applied, with wheat planted on October 15 or later. At zero N, the double-crops of cowpea planted on July 15 and wheat planted on November 30 were the most beneficial of all the 72 double-cropping systems studied. With a delay in planting cowpea, the percentage of beneficial double-cropping systems decreased. At N rates other than zero, fallow-wheat monocropping systems were more beneficial than cowpea-wheat double-cropping systems, and the benefit was greater at a higher N rate. At 100 kg N ha-1, the monocrop of wheat planted on October 15 was the most beneficial of all the 94 systems studied. Results further showed that fallow-wheat yields increased almost linearly with an increase in N rate from 0 to 100 kg∙ha-1. Fallow-wheat grain yields were quadratically associated with planting dates. With an increase in N rate, wheat yields reached the peak with an earlier planting date. Wheat yields produced under monocropping systems were greater than those produced under double-cropping systems for any cowpea planting date. Cowpea yields produced under monocropping systems were greater than those produced under any double-cropping system. The relationship between cowpea grain yields and planting dates was quadratic, with July 1 planting date associated with the maximum yields.

The Possible Effect of Climate Warming on Northern Limits of Cropping System and Crop Yield in China

Significantly increasing temperature since the 1980s in China has become a consensus under the background of global climate change and how climate change affects agriculture or even cropping systems has attracted more and more attention from Chinese government and scientists. In this study, the possible effects of climate warming on the national northern limits of cropping systems, the northern limits of winter wheat and double rice, and the stable-yield northern limits of rainfed winter wheat-summer maize rotation in China from 1981 to 2007 were analyzed. Also, the possible change of crop yield caused by planting limits displacement during the periods 1950s-1981 and 1981-2007 was compared and discussed. The recognized calculation methods of agricultural climatic indices were employed. According to the indices of climatic regionalization for cropping systems, the national northern limits of cropping systems, winter wheat and double rice, and the stable-yield northern limits of rainfed winter wheat-summer maize rotation during two periods, including the 1950s-1980 and 1981-2007, were drawn with ArcGIS software. Compared with the situation during the 1950s- 1980, the northern limits of double cropping system during 1981-2007 showed significant spatial displacement in Shaanxi, Shanxi, Hebei, and Liaoning provinces and Beijing municipality, China. The northern limits of triple cropping system showed the maximum spatial displacement in Hunan, Hubei, Anhui, Jiangsu, and Zhejiang provinces, China. Without considering variety change and social economic factors, the per unit area grain yield of main planting patterns would increase about 54-106% if single cropping system was replaced by double cropping system, which turned out to be 27- 58% if double cropping system was replaced by triple cropping system. In Liaoning, Hebei, Shanxi, Shaanxi, Gansu, and Qinghai provinces, Inner Mongolia and Ningxia autonomous regions, China, the northern limits of winter wheat during 1981-2007 moved northward and expanded westward in different degrees, compared with those during the 1950s-1980. Taking Hebei Province as an example, the northern limits of winter wheat moved northward, and the per unit area grain yield would averagely increase about 25% in the change region if the spring wheat was replaced by winter wheat. In Zhejiang, Anhui, Hubei, and Hunan provinces, China, the planting northern limits of double rice moved northward, and the per unit area grain yield would increase in different degrees only from the perspective of heat resource. The stable- yield northern limits of rainfed winter wheat-summer maize rotation moved southeastward in most regions, which was caused by the decrease of local precipitation in recent years. During the past 50 yr, climate warming made the national northern limits of cropping systems move northward in different degrees, the northern limits of winter wheat and double rice both moved northward, and the cropping system change would cause the increase of per unit area grain yield in the change region. However, the stable-yield northern limits of rainfed winter wheat-summer maize rotation moved southeastward due to the decrease of precipitation.

The El Niño-Southern Oscillation (ENSO) Effects on Cowpea and Winter Wheat Yields in the Semi-Arid Region of the Southern US

Information is limited on the effects of climate variability on cowpea (Vigna unguiculata L.) and winter wheat (Triticum aestivum L.) yields in the semiarid region of the southern US. Using the Decision Support System for Agrotechnology Transfer (DSSAT) crop model and weather data spanning 81 years, we assessed the impact of El Niño-Southern Oscillation (ENSO) on the grain yields of these crops in the Llano Estacado region of the southern US as affected by cowpea and wheat planting dates and N application rate. Simulated results showed that the El Niño phase of ENSO produced about 30% more yields of mono-cropped cowpea than those produced under the La Niña phase, especially with the cowpeas planted in July. The cowpea yields under El Niño were about 10% more than the 81-year average normal yield, whereas those under La Niña were about 20% less. At the N rates of 0, 50, and 100 kg·ha−1, regardless of wheat planting dates, the El Niño years produced, respectively, about 8%, 40%, and 60% higher wheat yields than those produced in the La Niña years, and about 5%, 20%, and 27% more than the 81-year average normal yield. In the La Niña years, the wheat yields at 0, 50, and 100 kg N ha−1 were, respectively, about 5%, 15%, and 20% less than the normal yield with similar N levels. The impact of ENSO on wheat yields under cowpea-wheat double-cropping systems was significant, especially for the wheat crops planted on October 15 (October 30) or later following the cowpea crops planted in June (July). At zero N, the mono-cropped wheat yields were not impacted by ENSO due to N limitation. However, the double-cropped wheat yields were impacted by ENSO even when no N fertilizer was applied due to high soil N status caused by N transfer from cowpea stover residues and roots. Results indicated that management strategies need to be attentive to ENSO forecasts and adjust potential planting dates and N application rates with the ENSO phase to avert risks of crop failure and economic loss.

Assessing Cowpea-Wheat Double Cropping Strategies in the Southern United States Using the DSSAT Crop Model

Information is limited on the potential of cowpea-wheat double cropping in the southern United States to enhance soil health and increase net returns. Using the Decision Support System for Agrotechnology Transfer (DSSAT) crop model and weather data spanning 80 years, we assessed the effects of soil type (Darco: Grossarenic Paleudults and Lilbert: Arenic Plinthic Paleudults), N application rate (0, 100, and 200 kg•ha−1), and El Niño-Southern Oscillation (ENSO) on the grain yields of double-cropped cowpea (Vigna unguiculata L.) and wheat (Triticum aestivum L.) in this region. Yield differences were tested using the pairwise Wilcoxon rank sum test. Results showed that yields of wheat that followed cowpea (cwheat) were greater than those that followed fallow (fwheat). The soil type effects on cwheat and fwheat yields decreased with an increase in N rate. The soil type effect on cowpea yields was greater during La Niña. The ENSO impact on cowpea yields was greater on the less fertile soil Darco. Yields of cwheat and fwheat increased with an increase in N rate up to 100 and 200 kg•ha−1, respectively. The yield response of cwheat to N rate was less than that of fwheat. The N rate effects on cwheat and fwheat yields were greater on Darco and under El Niño. Yields of cowpea were greatest under El Niño, whereas those of wheat were greatest under La Niña. The ENSO effect on cowpea yields was greater on Darco. With an increase in N rate, the effect of ENSO was diminished.

Effects of Tillage and Planting Methods on Narrow and Wide Row Cotton Production

Cotton (Gossypium hirsutum L.) is an economically important crop for the Southern United States. The southern US also has a long growing season suitable for double cropping a second crop after small grains;however, the harvest date for the small grains typically occurs after the optimum planting window for cotton which reduces yield potential. A relay intercropping system was developed at Clemson University that allows interseeding of cotton into standing wheat 2 to 3 weeks before harvest with interseeded cotton yields similar to the conventional mono-cropped cotton. Therefore, the objectives of this study were 1) to determine the optimum tillage and planting methods for narrow row (76-cm) and wide row (97-cm) cotton, and 2) to compare narrow and wide row systems for conventional tillage cotton, cotton interseeded into standing wheat, and cotton planted into a terminated wheat cover crop on coastal plain soil. Two replicated tests were conducted to accomplish these objectives. In Study 1, conventional narrow row cotton combined with a deep tillage operation using Paratill yielded 23% more than conventional wide row cotton which had a deep tillage operation with a subsoiler just before planting. There were no differences between the conventional (97-cm row spacing) mono-crop and interseeded cotton yields. In Study 2, there was no significant difference in yield between narrow-row and wide-row cotton for each cropping system during the two years study. Both wide and narrow-row full season cotton had significantly higher yields than interseeded and cover crop planting systems in year two of the study. The two conservation cropping practices, wheat used as a cover crop and interseeding, showed considerable promise for reducing energy requirements, soil erosion, and wind-borne cotton damage associated with bare soil in conventional tillage. This research demonstrates the benefits of interseeding and narrow row spacing for sustainable cotton production in coastal plain soils of the Southern United States.

豫北两熟区不同夏播作物对后茬冬小麦中后期群体微环境及产量的影响

为探讨不同夏播作物前茬对后茬冬小麦生长和产量的影响,在河南省新乡市获嘉县开展田间二因素试验,设置两个不同施肥水平(常规施肥和不施氮肥)和三种夏播作物前茬(玉米、大豆和花生),分析小麦拔节期至成熟期叶面积指数(LAI)、叶夹角(LA)、光合有效辐射(PAR)、叶片叶绿素含量(SPAD)、叶绿素荧光(F_(v)/F_(m)),以及土壤含水量(SWC)、土壤温度(Ts)和土壤呼吸速率(Rs)变化,并在成熟期测定小麦产量及其构成因素。结果表明,与常规施肥(CK)相比,不施氮肥条件下不同前茬的小麦LA略增,而LAI、IPAR、SPAD、F_(v)/F_(m)、SWC、Ts和Rs均有所降低。不施氮肥条件下,花生前茬的小麦LAI、IPAR、SPAD、F_(v)/F_(m)、SWC、Ts和Rs均显著低于其他两种前茬(P<0.05),其中花生、大豆和玉米前茬的SWC较CK的降幅分别为13.56%、13.39%和10.77%。与CK相比,不施氮肥条件下,花生前茬的小麦LA较CK的增幅在3种前茬中居中,小麦株型较为紧凑,有利于改善植株下层光合辐射,为群体生长创造良好的光合和土壤条件,其产量较玉米和大豆前茬分别高20.0%和21.9%;玉米前茬的整体表现不如大豆和花生前茬,但其和花生前茬的小麦千粒重和群体数均较高,因而产量居中;大豆前茬的小麦结实小穗数和干物质量较高,但其小麦千粒重较低,最终籽粒产量也较低。综合来看,在两熟种植模式中,选用花生作为冬小麦的前茬作物是豫北地区一年两熟区作物配置的一种较优选择。

施用有机肥和秸秆还田对旱地玉-麦二熟体系作物产量、品质和化肥效率的影响

为探明施用商品有机肥和秸秆还田对旱地夏玉米-冬小麦二熟体系作物产量、品质和肥料利用效率的影响,于2015—2020年度设置不施肥+秸秆不还田(CK)、施氮磷肥+秸秆不还田(NP)、施氮磷肥+秸秆不还田+商品有机肥(NPO)和施氮磷肥+秸秆还田(NPS)4个处理进行田间试验,测定并分析作物产量、氮磷肥农学效率、籽粒养分含量、蛋白质含量以及冬小麦籽粒中蛋白质组分含量。结果表明:(1)与NP和NPO处理相比,NPS处理夏玉米5 a平均产量分别显著提高21.33%和20.77%,周年产量分别显著提高9.99%和13.43%,但3个施肥处理间小麦产量差异不显著。(2)施用商品有机肥和秸秆还田对夏玉米、冬小麦的籽粒品质均有显著影响。与NP处理相比,NPO处理冬小麦籽粒各蛋白质组分含量提高5.69%~8.28%;NPS处理冬小麦籽粒氮含量、钾含量和各蛋白质组分含量分别提高4.68%、3.96%和7.75%~11.38%。相较于NPO处理,NPS处理冬小麦籽粒钾含量、谷蛋白含量、贮藏蛋白含量和谷醇比分别显著提高14.41%、9.86%、5.39%和9.65%,夏玉米籽粒蛋白质含量、产量和籽粒氮、籽粒磷含量以及周年蛋白质产量分别显著提高6.45%、28.89%、6.40%、23.08%和10.43%。(3)相较于NP和NPO处理,NPS处理夏玉米氮肥的农学效率分别提高118.35%和113.25%,周年氮、磷肥农学效率分别提高42.83%和64.36%、42.86%和64.27%,但3个施肥处理间冬小麦氮肥、磷肥农学效率5 a均值无显著差异。综合来看,长期施用商品有机肥和秸秆还田可改善冬小麦籽粒中的蛋白质组分特性,秸秆还田还能增加夏玉米籽粒钾含量和冬小麦籽粒蛋白质含量和蛋白质产量,秸秆还田较施用商品有机肥更利于提高旱地玉-麦二熟区作物产量、品质和肥料利用效率。综上所述,施氮磷肥+秸秆还田的管理模式更适宜在旱地玉-麦二熟区进行推广。

氮肥减量后移改善植株光合特性提高麦-玉周年产量及经济效益

【目的】针对黄淮海平原传统施氮技术下,小麦-玉米两熟体系作物生育后期土壤氮肥供应不足导致籽粒减产等问题,探讨氮肥减量后移对植株光合特性、干物质积累及周年籽粒产量和经济效益的影响,为进一步优化施氮制度提供理论依据。【方法】2020—2023年,于山东济阳典型麦-玉两熟种植区,设置周年施氮400 kg·hm^(-2)传统农户处理(CK,小麦季200 kg·hm^(-2):65%基肥+35%返青肥,玉米季200 kg·hm^(-2):100%基肥)、周年减氮10%(SN,小麦季180 kg·hm^(-2):50%基肥+50%返青肥,玉米季180 kg·hm^(-2):100%基肥)、周年减氮20%(NH,小麦季180 kg·hm^(-2):22.2%基肥+33.3%返青肥+44.5%抽穗肥,玉米季140 kg·hm^(-2):28.6%基肥+71.4%大喇叭口肥)和周年减氮30%(NL,小麦季140 kg·hm^(-2):43%返青肥+57%抽穗肥,玉米季140 kg·hm^(-2):100%大喇叭口肥)4种施氮制度,研究不同施氮制度下麦-玉两熟体系的光合特性、籽粒产量和经济效益。【结果】氮肥后移优化了氮肥减量条件下作物光合特性,其中,叶面积指数3年均值,小麦拔节和开花期NL较CK、SN和NH处理分别显著提高19.0%—40.1%和21.6%—36.7%,夏玉米吐丝期NL较CK和SN处理显著提高6.8%—7.3%;叶片SPAD值3年均值,冬小麦拔节和开花期NL较CK、SN处理分别显著提高7.7%—10.0%和7.4%—12.9%,灌浆中期NL较CK、SN和NH处理显著提高5.2%—16.2%;夏玉米大喇叭口期NL和NH较CK、SN处理3年均值分别显著提高9.0%—9.4%和6.7%—7.1%,吐丝和灌浆中期NL较CK、SN和NH分别显著提高5.1%—9.4%和4.1%—9.2%;净光合速率3年均值,小麦拔节、开花和灌浆中期NL较CK、SN处理分别提高8.9%—13.3%、14.0%—18.1%和20.1%—24.4%;夏玉米大喇叭口、吐丝和灌浆中期NL较CK、SN处理分别提高4.2%—5.7%、8.7%—13.4%和7.7%—12.8%。NL处理通过增加氮肥后移量,改善了各生育阶段地上部干物质积累强度,稳定或提高了各生育时期地上部干物质积累量,冬小麦拔节、开花和成熟期地上部干物质积累量的3年均值较CK分别显著提高26.7%、27.4%和18.1%,夏玉米吐丝期显著提高14.4%。氮肥后移通过改善氮肥减量条件下光合特性,促进了各生育时期地上部干物质积累,最终实现冬小麦、夏玉米及周年籽粒产量的3年均值,NL较CK处理分别显著提高20.5%、18.1%和19.1%,经济效益分别显著提高32.4%、23.8%和27.9%。【结论】黄淮海平原麦-玉两熟体系,周年减氮30%制度下通过增加氮肥后移量,改善了作物光合特性(叶面积指数、叶片SPAD值和净光合速率),优化了各生育阶段地上部干物质积累强度和干物质积累量,从而促进冬小麦、夏玉米及周年总产和经济效益的提高。

鲁东南稻区稻麦两熟节水增效生产新技术

从稻麦品种的选择与搭配、茬口与播期、播前种子处理、整地、播栽方式与用种量、施肥、水分管理、病虫草害防治、收获等方面总结介绍了鲁东南稻区稻麦两熟节水增效生产新技术。该技术主要针对临沂市及周边中粳中熟同生态区稻麦两熟粮食生产,比传统手插秧种稻方式大幅度减轻劳动强度、节约人力物力,有利于推动种稻方式由传统手插秧向旱育机插秧和机直播转变,社会、经济、生态效益都十分显著。

Nuclear Fusion during Early Stage of Microspore Embryogenesis Indicates Chromosome Doubling in Wheat (Triticum aestivum)

Studies of barley and maize indicate that chromosome doubling occurs via nuclear fusion during an early stage of microspore embryogenesis, but the time and mechanism by which chromosome doubling occurs in bread wheat (Triticum aestivum) remains undetermined. The purpose of this study was to determine the relative time during induction culture when chromosome doubling may occur in wheat, and to identify early indicators for doubled haploid microspores. Microspore nuclei were stained with 4’,6-diamidino-2-phenylindole (DAPI) and observed under a fluorescent microscope on the day of isolation, three days after isolation, and six days after isolation. The change in the percentage of microspores containing a single small nucleus, two small nuclei, a single enlarged nucleus, and three or more nuclei was then tracked throughout the six-day period. Ploidy levels were estimated by determining the cross-sectional area and number of nucleoli in microspores containing small and large nuclei then comparing the results of each respective cell-type. The percentage of microspores containing enlarged nuclei increased throughout the six-day test period, and the percentage of binucleated microspores containing small nuclei decreased. Comparison of the changes in average percentage of microspores containing a single small nucleus, binucleated microspores, microspores containing a single large nucleus, and multinucleate microspores on days 0, 3, and 6 indicates that nuclei classified as “small” are likely haploids and nuclei classified as “large” are doubled haploids. The percentage of microspores with enlarged nucleus (nuclei) during the first six days of induction culture could be used as an early indicator for the frequency of chromosome doubling in wheat microspore culture.

秸秆还田和有机肥配合替代1/3化肥对旱地玉-麦产量、蛋白质含量和化肥利用效率影响

为研究长期秸秆还田和有机肥配合替代部分化肥对玉-麦一年两熟种植下产量、品质和化肥效率的影响,2015-2020年,依托中国农业科学院洛阳旱农试验基地始于2007年的长期定位试验,设置不施肥对照(CK)、玉米小麦季均常规施用氮磷钾化肥(NPK)、秸秆还田和有机肥配合替代小麦季1/3氮磷钾化肥(SORF)3个处理,研究2015—2020年玉-麦一年两熟种植下作物产量、化肥利用效率,2019—2020年玉米和小麦籽粒氮磷钾养分含量、蛋白质含量和蛋白质产量,以及2020年小麦籽粒蛋白质及其组分含量。结果表明:(1)SORF处理玉米增产增效作用优于NPK处理,5年平均产量提高10.0%,但二者间小麦和周年产量差异未达显著水平(p>0.05)。(2)施肥显著提高玉米和小麦籽粒氮磷钾含量,其中SORF较NPK处理又显著增加籽粒氮含量,从而使玉米籽粒蛋白质含量和蛋白质产量较NPK分别显著提高6.7%和17.8%,小麦籽粒蛋白质含量和蛋白质产量分别显著提高8.0%和6.3%,周年蛋白质产量显著增加10.8%。(3)SORF和NPK处理较CK均可显著提高小麦籽粒中各蛋白质组分含量及谷醇比,协同提高小麦籽粒蛋白质含量和籽粒品质。SORF较NPK处理还可提高除球蛋白外的其他蛋白组分含量,但谷醇比的增幅不显著。(4)与NPK相比,SORF处理下玉米、小麦和周年的氮肥农学效率分别显著提高54.8%,31.2%和37.3%,氮肥偏生产力分别显著提高10.0%,45.6%和20.7%,小麦、周年的磷(钾)肥农学效率和偏生产力分别提高31.2%,77.3%和45.6%,55.7%。综合来看,秸秆还田和有机肥配合替代1/3化肥(SORF)不仅有利于提高玉米产量,玉米、小麦的籽粒蛋白质含量和蛋白质产量,以及化肥农学效率和偏生产力,而且可提高小麦籽粒蛋白组分含量,是旱地玉-麦一年两熟区兼顾产量品质效率的施肥模式。

氮素调控对冬小麦-夏玉米一年两熟N_(2)O排放及产量的影响

[目的]探究氮素调控对江淮丘陵地区冬小麦—夏玉米一年两熟(麦玉两熟)N_(2)O排放及产量的影响,为该地区小麦和玉米稳产减排提供理论依据。[方法]以江淮丘陵地区麦玉两熟为研究对象,设置不施氮肥(CK)、常规施氮(CN)、生物炭与氮肥配施(SN)、硝化抑制剂与氮肥配施(XN)和叶面喷肥(PN)5个处理,采用静态箱—气相色谱法,分析不同氮素调控措施下土壤N_(2)O排放和作物产量变化。[结果]土壤N_(2)O排放呈季节性变化,主要集中在施肥和降雨后的15 d内,玉米季是排放高峰期。与CN处理相比,小麦季XN和SN处理的N_(2)O累积排放量分别显著降低46.07%和25.10%,玉米季XN、SN和PN处理的N_(2)O累积排放量分别显著降低70.70%、64.01%和9.87%。从周年排放看,XN和SN处理的N_(2)O累积排放量比CN处理分别显著降低59.36%和46.21%,PN与CN处理间无显著差异。与CN处理相比,XN和SN处理的作物周年产量分别显著增加13.35%和11.27%,N_(2)O排放系数分别显著降低59.50%和46.28%。[结论]综合考虑N_(2)O排放和作物产量,硝化抑制剂与氮肥配施可作为江淮丘陵地区麦玉两熟稳产减排的最佳氮肥调控措施。

华北玉麦两熟区犁式秸秆翻埋装置参数优化

华北玉麦两熟地区玉米收获后土壤表面秸秆量大,传统还田作业效果不理想,且长期的旋耕和免耕作业导致土地形成了犁底层和土壤板结,影响小麦播种作业及土地的可持续发展利用。为此,综合考虑秸秆还田和打破犁底层等问题,设计了用于华北玉麦两熟区整地机的翻埋装置,并对装置进行参数优化。利用离散元仿真技术、数字化土槽与田间试验相结合的方法,对整地机的翻埋装置进行分析优化。试验结果表明:秸秆翻埋率为97.4%,耕深稳定性系数为91.35%,性能稳定,满足小麦播种要求。

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。

麦棉两熟共生期对棉苗叶片光合性能的影响

黄淮棉区主要麦棉两熟种植方式(3∶1和3∶2 式)共生期遮荫对棉苗叶片光合性能影响的研究结果表明,棉苗叶片叶绿素含量和光合速率随叶位升高呈单峰曲线变化,其峰值叶位相同,变化趋势随遮荫程度增大而降低。与 3∶1式比较,3∶2式棉苗基部叶片叶绿素降解慢,叶绿素a/b 值增大,暗呼吸作用增强,其相应叶片有效捕捉光能的能力和生理活性提高。共生期遮荫降低了功能叶光饱和点、光补偿点和CO 饱和点,可提高叶片在较低光2强条件下对光能的捕捉能力,利于光合作用进行。与常规棉比较,麦棉共生期3∶2式遮荫对棉苗生长发育的影响较小,而 3∶1式遮荫则不利于棉苗生长发育。

套作棉根际与非根际土壤酶活性和养分的变化

在棉麦两熟双高产条件下研究了棉花根际与非根际土壤酶活性和养分含量的变化.结果表明,套作棉土壤脲酶、蔗糖酶、蛋白酶及过氧化氢酶活性随生育进程的变化趋势与单作棉表现一致,但整个生育期套作棉根际与非根际土壤各种酶活性均明显高于单作棉.套作棉根际与非根际土壤养分含量在麦棉共生期低于单作棉或差异较小,而在麦收后则显著高于单作棉.套作棉土壤养分含量随生育进程的变化趋势与单作棉大体相同,但一些养分的吸收高峰晚于单作棉.无论套作棉还是单作棉,根际土壤酶活性和养分含量高于非根际.土壤各养分含量与土壤脲酶、蔗糖酶和蛋白酶活性呈显著(P=0.05,n=32)或极显著(P=0.01,n=32)相关,与土壤过氧化氢酶活性相关不显著.

稻麦两熟制不同耕作方式与秸秆还田对小麦产量和品质的影响

为给稻套麦的高产栽培和秸秆科学还田提供理论依据,通过大田小区和网室水泥池微区的3年定位试验,比较研究了稻麦两熟条件下免耕套播秸秆覆盖、免耕套播高茬、翻耕秸秆还田、翻耕秸秆不还田(CK)4个耕作方式处理对小麦产量和品质的影响。结果表明,在同期同量播种条件下,免耕套种小麦穗数较少,千粒重较高,第一年实际产量略低。但随着连续免耕时间的延长,残留秸秆较多,稻田水绵严重,影响套种小麦出苗,免耕处理产量明显降低,免耕秸秆覆盖还田比翻耕不还田平均降低7.27%,因而必须改变播种方式或轮耕。耕翻秸秆覆盖还田在麦季的产量有增有减,比翻耕不还田平均减产1%左右。免耕与秸秆还田条件下虽然小麦容重降低,但出粉率提高,小麦的加工品质改善。在土壤肥力较低时,免耕处理小麦的蛋白质和湿面筋含量有降低趋势;而秸秆覆盖还田可提高蛋白质和湿面筋含量,有利于改善中强筋专用小麦的品质。

中国麦棉两熟种植制度的研究

棉麦两熟种植制度主要分布在中国黄淮海棉区和长江中下游棉区。介绍了麦棉两熟种植制度的发展意义与历史,基本模式,主要技术和理论基础研究等,提出了进一步发展棉麦两熟制度需要克服植棉比较效益低和管理繁琐两个突出问题,十分迫切需要科技从简化管理、节本种植、机械化和轻简化等方向上进行创新和推进。