河套灌区玉米膜下滴灌灌溉制度研究

为研究河套灌区膜下滴灌条件下玉米高产、节水、高效的灌溉制度,通过两年的田间试验,分析了膜下滴灌条件下玉米的耗水量规律,用Jensen模型建立了玉米的水分生产函数,并对玉米的灌溉制度进行了优化。结果表明:膜下滴灌条件下玉米在苗期对水分的敏感性较弱,此时期缺水对产量的影响较小;在拔节—抽雄、抽雄—花期和花期—灌浆期对水分的敏感性较强,此时期亏水将会减产。对玉米膜下滴灌灌溉制度优化得出:灌溉定额为275~325 mm,玉米的产量较高;对灌水量的分配为苗期—拔节灌水量为20~40 mm,拔节—抽穗的灌水量为40~60 mm,抽雄—开花的灌水量为115 mm,开花—灌浆的灌水量为80 mm,灌浆—乳熟的灌水量为20~40 mm,较本地常规地面灌每公顷节水2 546.25~3 296.25 mm,节水效果十分显著。     

玉米叶面积生长的影响研究

通过对西峰农业气象试验站观测的玉米叶面积指数资料变化分析得出:玉米叶面积指数年内变化呈缓慢增长—快速增长—缓慢下降趋势;年际变化因发育期不同,环境因子不同,存在着较大差异;叶面积指数的变化与降水相关较好,与积温和日照仅在三叶~七叶期呈现正效应,其它时段相关不显著;玉米产量与抽雄和乳熟期叶面积指数显著相关,抽雄期叶面积指数小于3时,产量不高,达到4以上时,产量开始下降,叶面积指数适合范围为3~4,高产田为3.5以上。     

不同地下水埋深夏玉米产量及产量构成关系研究

依据天长市二峰灌溉试验站2009年夏玉米地下水位埋深试验资料,通过6种地下水位控制处理和对照夏玉米试验,探讨了不同地下水埋深对夏玉米产量及产量构成关系的影响。结果表明:夏玉米的地下水补水量、夏玉米生长期的土壤含水量、夏玉米叶面积指数均随着水位埋深加大而降低;夏玉米植株高度在抽雄前期受地下水埋深影响较大,到开花期则基本无影响;同时试验表明地下水位埋深对产量的影响较大,在拔节前期地下水位埋深大于60 cm或在拔节后期地下水位埋深小于40 cm将影响玉米总穗粒数和百粒重,导致严重减产。     

基于WOFOST模型的辽宁省春玉米干旱灾损风险评估

利用锦州农业气象试验站的作物生长发育和土壤实测数据对WOFOST模型水分胁迫模块进行了调参，适用性验证表明，WOFOST模型适用于辽宁省春玉米生长发育和产量的模拟，辽宁省春玉米受干旱的影响可以利用WOFOST模型较敏感地反映出来。利用调参后的WOFOST模型模拟了全生育期及出苗~拔节、拔节~抽雄、抽雄~乳熟和乳熟~成熟各阶段发生轻、中、重旱情景对辽宁省春玉米产量的影响，并根据模拟结果确定了不同干旱风险等级下辽宁省东、中、西部玉米生产的灾损范围。结果表明：不同生育期发生干旱对产量的影响不同，总体上，抽雄~乳熟期发生干旱的影响最大，其次是拔节~抽雄期，而出苗~拔节期和乳熟~成熟期发生干旱对产量的影响较小，全省春玉米在抽雄~乳熟期发生重旱的减产风险达30%~70%；在相同干旱水平下，不同区域受影响程度也不同，在全生育期及各生育阶段发生轻、中、重旱情景下，干旱导致的减产率总体上表现为由东部向西部地区逐渐加重的趋势，在全生育期重旱情景下，辽宁省东部的春玉米减产率为40%~75%，中部为60%~90%，西部达65%~95%。     

不同灌溉制度对覆膜春玉米的耗水规律及产量的影响

研究了不同灌水定额和灌水次数处理下覆膜玉米的耗水规律和产量,试验结果表明:灌溉定额相同时,灌水次数的变化对产量有较大影响;灌溉次数较多的处理土壤平均含水率波动幅度较小,土壤水分能保持在一个比较稳定的范围.相同的灌水次数下,适当增加灌溉定额在一定程度上可增加作物产量,但超过一定值之后,产量并无显著提高.玉米的耗水量随着灌溉水量的增加而增加,玉米在拔节～抽雄、抽雄～乳熟期的耗水量最大,对水分亏缺最敏感,是需水关键期.水分利用效率随着灌溉量的增加而减少.     

宁夏中部干旱带玉米生育期热量条件时空特征分析

利用宁夏中部干旱带盐池、同心及海原三地1988—2013年逐日气象资料建立玉米全生育期及各主要生育阶段温度适宜度模型,并对宁夏中部干旱带玉米生育期温度适宜度及≥10℃积温进行时空变化分析。结果表明:宁夏中部干旱带玉米全生育期温度适宜度以及≥10℃积温均呈波动上升趋势,三地的温度适宜度从大到小依次为同心、盐池、海原,数值分别为:0.966,0.911和0.726。温度适宜度在播种~出苗,出苗~拔节,拔节~抽雄,开花吐丝~成熟阶段均呈上升趋势,其中拔节~抽雄阶段上升速率最快,速率为0.03·10a~(-1)。盐池玉米的热量关键期为抽雄~开花吐丝阶段,同心为播种~出苗阶段,而海原为拔节~抽雄阶段。     

冬小麦叶片形状系数的变异性

研究了2014-10—2015-06生长季内6个不同熟性冬小麦品种全生育期内叶片形状系数的变化规律,将小麦生育期划分为出苗、返青、拔节、抽穗、开花、成熟等6个不同生长阶段,依次采样计算各个阶段的α均值,同时考虑α值在单个植株不同叶片之间的差异,以及不同冬小麦品种之间的差异。结果表明:α值总体在0.59到0.71之间,随冬小麦生育期的变化而变化,自苗期到开花期波动增大,开花后缓慢下降;在单个植株之内,α值变异性较大,开花期最为稳定,开花后变异性增加;不同熟性冬小麦品种之间,α值在拔节、抽穗和开花期表现出显著差异,而在出苗、返青和成熟期,差异不显著。因此,建议最好在不同的作物生长阶段采用不同的叶片性状系数,以提高叶面积模拟和预测精度。对全生育期3种熟性6个冬小麦品种的1 485个叶片的面积和长宽乘积进行线性回归分析,可知总体的冬小麦叶片形状系数值约为0.66。以叶面积模型LA=0.66×L×W来估算冬小麦叶片面积,其总体的相对均方根误差(RRMSE)约为4.40%,绝对相对误差(absolute relative error,ARE)约为13.05%,在5种不同叶面积估算模型中精度最高,因此推荐该模型用于估算田间小麦叶片面积。     

辽宁地区玉米耗水量与产量的关系

为探讨生长季自然降水条件下水分状况对玉米产量的影响,利用锦州2011、2012年和2014年玉米分期播种试验数据和1981—2010年辽宁农业气象历史资料,研究干旱年份水分与玉米产量的定量关系。结果表明:玉米产量和总耗水量间呈二次抛物线的关系(R~2=0.793,F=105,P=0.0001,n=57),当耗水量达到400~600 mm时,玉米能够获得高产;玉米不同生育阶段需水量呈现抽雄~乳熟期拔节~抽雄期出苗~拔节期乳熟~成熟期播种~出苗期的变化规律,各阶段日耗水强度分别为5.75、4.78、2.36、1.84 mm·d~(-1)和1.35 mm·d~(-1)。在分析相对叶面积指数和相对作物系数关系的基础上,提出了作物水分胁迫系数的相对叶面积订正方法,建立了以Jenson模型为基础的玉米水分生产函数模型。     

杨凌地区冬小麦-夏玉米水分供需适配性分析

采用1984—2015年气象观测站逐日气温、降水等资料,计算冬小麦-夏玉米各生育期阶段的需水量和有效降水,采用趋势分析及数理统计方法分析近32 a陕西杨凌示范区冬小麦和夏玉米生育期的降水特征,并结合作物需水特征分析其水分供需的适配性。结果表明:冬小麦和夏玉米生育期的有效降水都表现出不稳定性,除个别年份外,大多年份降水不能满足作物的需水要求。冬小麦播种~返青阶段有效降水量仅为18.9 mm,需水量在126.5 mm左右;返青~拔节阶段有效降水13.5 mm,且变异系数达130%,而需水量为81.2 mm;拔节~孕穗阶段有效降水为37.6 mm,但小麦在此阶段需水量达206.6 mm;根据小麦生理需水规律,一般年份在冬前灌水45~50 mm,拔节期灌水50 mm左右,孕穗期视情况而定。夏玉米播种~出苗阶段有效降水变异系数最大,其次是拔节~抽雄阶段,各生育阶段有效降水均表现出不稳定性。出苗~抽雄阶段平均有效降水量为126.8 mm,此阶段玉米需水量为157.2 mm;玉米抽雄~灌浆阶段平均有效降水73.9 mm,而需水量为166.6 mm;根据玉米生理需水规律,一般年份可在夏玉米大喇叭口期灌水50 mm左右,抽雄灌浆期灌水60 mm。     

胶东地区夏玉米棉铃虫发生为害规律及其防治措施

夏玉米棉铃虫卵,大部分散产于夏玉米尚未开花的雄穗上。抽雄未开花玉米落卵量约为抽雄开花者的3倍,是心叶末期玉米上的35倍。此期为夏玉米棉铃虫产卵盛期:抽雄开花盛期,是其卵的孵化盛期。幼虫成活率为卵量的10.53±1.04％。在夏玉米抽雄未开花期用1％1605粉或1605毒砂防治两次,幼虫虫口减退率为71.7-81.5％,在保障稳产高产的前提下,适当调节播期可避开夏玉米棉铃虫的产卵盛期,减轻危害。     

陇东黄土高原主要农作物生长状况评定指标体系的建立

以陇东黄土高原主要农作物冬小麦、玉米为研究对象,提出了作物生长势的基本概念,同时分析了冬小麦、玉米各发育期生长势的影响因素,最后以生长势为量化指标,建立了陇东地区冬小麦、玉米不同发育时段生长状况评定指标体系。该体系可使农作物生长状况评定由定性向定量,由多要素向单要素转化,不但剔除了评定的不确定因素和模糊因素以及主观误差,而且使评定方法更加简便、科学。     

旱农区不同种植模式作物最佳补灌时期和适宜补灌量研究

The effect of supplementary irrigation with catchment rainfall on crop yield increment and its water use efficiency was studied on upland field with different cropping patterns to make full use of the natural rainfall. The results showed that the crop yield and water use efficiency was increased significantly after 45 mm～90 mm supplementary irrigation, as compared with no irrigation. The optimum total amounts of supplementary irrigation for all three cropping patterns were 90 mm. The optimum amounts and periods of irrigation for mono-cultured wheat were 8mm before sowing and 82　mm at its boot stage, those for film-covered mono-cultured were 90mm at its big horn stage, and those for multipled cropping wheat and film-covered corn were 4mm before wheat sowing and 19　mm both at jointing and boot stages, and 24　mm both at jointing and big horn stages of corn. The results were suitable for northern upland fields.     

A comparison of the tolerance by winter wheat of herbicide mixtures containing dicamba and 2,3,6-TBA, or ioxynil

The tolerance by winter wheat of two types of herbicide was examined in field experiments over 3 years. When overdosed or sprayed late, an ioxynil + mecoprop mixture had a greater margin of safety to the crop than mixtures containing dicamba or 2,3,6-TBA. Herbicide mixtures containing MCPA, applied before the leaf sheaths of the crop began to extend in the spring caused ear deformities. Spraying dicamba mixtures when the crop was jointing resulted in narrowed ears and shrivelled grain, In one experiment the latter effect was produced by a dicamba mixture, at twice the recommended dose, when sprayed on any of ten dates, covering crop development stages from 6-leaves through to jointing. Varieties differed in their tolerance of the dicamba mixtures; Maris Ranger was most sensitive but part of this difference could have been due to differences in the stage of development of the varieties at the time of spraying.     

不同生育时期非充分灌溉对间作作物产量构成因子及收获指数的影响

针对内蒙古河套灌区干旱缺水的实际情况,以春小麦间作玉米、春小麦间作向日葵复合群体为研究对象,以不同生育期的非充分灌溉为试验处理,进行间作模式下的非充分灌溉试验。结果表明:间作下小麦分蘖期每多灌溉15 mm有效分蘖数提高5.4%~15.07%,而乳熟期随着水分胁迫加剧间作模式下的小麦穗粒数、千粒重、产量均呈现出先升高后降低的规律。对于间作下的玉米产量构成,适当减少小麦分蘖与拔节期的灌水量,相应增加小麦乳熟与玉米灌浆吐丝期的灌水量,有利于大幅提高缺水地区间作模式下的玉米产量,且随着灌水总量的升高,穗粒数以1.27~2.47粒·mm~(-1)的速度递增,产量以62.24,94.93,29.73 kg·hm~(-2)·mm~(-1)的"S"型曲线逐渐升高。而对于间作下的向日葵产量构成,其主要受小麦乳熟期与向日葵现蕾期水分处理的影响,且随灌水总量的提高间作向日葵的单株粒数呈先升后降的规律,而百粒重和产量则呈"N"型和"M"型规律变化。对于不同水分处理下各间作作物对水分的敏感指数表现为小麦的敏感指数最高,玉米次之,向日葵最低。不同水分处理对各间作作物收获指数的影响表现为间作模式下的小麦受水分胁迫后其收获指数普遍提高,间作模式下玉米的收获指数随灌水总量上升而逐渐上升,而间作模式下受水分胁迫处理的向日葵收获指数反而下降。     

保水剂用量对冬小麦光合特性及水分利用的影响

研究了冬小麦不同生育期(拔节、孕穗、灌浆)、不同用量保水剂(处理1,0 kg/hm 2;处理2,45.0 kg/hm2;处理3,52.5 kg/hm2;处理 4,60.0 kg/hm2)下冬小麦的光合速率、蒸腾速率、水分利用效率以及作物水分生产效率.结果表明:整个生育期内,冬小麦的净光合速率(Pn)、蒸腾速率(Tr)及水分利用效率(WUE)均表现为:孕穗期>灌浆期>拔节期.各生育期内,随保水剂用量的增加,光合速率、蒸腾速率和水分利用效率均增大.收获后,冬小麦水分生产效率各处理均优于对照,45.0、52.5和60.0 kg/hm2的处理分别比对照高:5. 4、5.5和10.4 kg/(mm*hm2).     

基于动态模拟的冬小麦水分胁迫敏感性研究

以关中平原为研究区域,在对农业技术转移决策支持系统(DSSAT)中的CERES-Wheat模型进行标定基础上,模拟冬小麦整个生育期以日为步长的实际蒸散量和潜在蒸散量,采用Jensen模型研究冬小麦不同生育时期对水分胁迫的敏感性。结果表明,无论旱作样点还是灌溉样点,冬小麦在同一生育时期对水分胁迫的敏感性相同,且拔节期的敏感性最强,抽穗~灌浆期次之,返青期和乳熟期依次递减。灌溉样点在拔节期和抽穗~灌浆期的水分胁迫敏感系数分别为0.589与0.342,对水分胁迫的敏感性相差较大,而旱作样点在两生育时期的水分胁迫敏感系数分别为0.405与0.383,对水分胁迫的敏感性相差较小,由于灌溉样点在拔节期发生水分胁迫现象可以通过及时灌溉以缓解缺水情况,因而会减弱其后抽穗~灌浆期的水分胁迫敏感性。根据水分胁迫敏感性,对不同生育时期缺水采取不同措施,较好地实现抗旱防旱资源的合理利用。     

施肥和绿肥翻压方式对旱地冬小麦生长及土壤水分利用的影响

通过田间试验研究渭北旱原不同施肥处理(不施肥;40 kg P2O5/hm2;豆科绿肥专用肥30 kg/hm2)对夏闲期豆科绿肥生长和后茬小麦生长的效果,探讨了夏季豆科绿肥翻压方式(提前翻压、提前覆盖,播前翻压和不种绿肥即夏季休闲)对后茬冬小麦产量及水分利用的影响。研究表明:与不施肥处理相比,豆科绿肥专用肥显著提高绿肥盛花期地上部生物量,但对根系生长没有明显作用;施用磷肥则更有利于绿肥根系生物量的提高;施用绿肥专用肥和磷肥处理的后茬小麦产量较高,特别是绿肥提前翻压时。绿肥提前翻压时冬小麦分蘖数较高、春季总茎数较高、单位面积穗数较高,产量显著高于绿肥提前覆盖、播前翻压和不种绿肥处理,水分生产效率显著高于不种绿肥处理。从绿肥翻压、小麦播前直至小麦拔节期,绿肥翻压方式的3个处理土壤0~200 cm剖面水分含量与休闲处理始终有明显差异。提前翻压处理与提前覆盖、播前翻压处理的差异主要在40 cm以上土层。     

Effect of tillage, cover crop and crop rotation on the composition of weed flora in a sandy soil

The development of integrated weed management strategies requires knowledge of mechanisms that influence compositional changes in weed flora. A 9-year study was initiated in 1988 at Delhi, Canada, on a loamy sand soil to evaluate the effect of tillage systems [conventional (CT) and no-till (NT)] and cover crops (only in NT) on weed density, species composition and associations, and crop yield in a winter wheat ( Triticum aestivum L.)/bean/winter wheat rotation. Three bean types: soyabean ( Glycine max L. Merr.), white bean ( Phaseolus vulgaris L.) and kidney bean ( P . vulgaris L.) were included. The NT system included variations: rye ( Secale cereale L.) or maize ( Zea mays L.) cover crop, volunteer wheat disked after harvest and wheat stubble. Data were collected in 1994, 1995 and 1996. Tillage systems, cover crops and crop type had differential effects on weed densities, species composition and associations. Weed densities were not affected by tillage or cover crops in wheat but, in the beans, densities were greater in the CT than in the NT systems. Various associations of weed species with tillage system, cover crop and crop type were observed. Crop yields were not affected by tillage type or cover crop, except that soyabean yields were highest in plots with cover crops.     

Weed populations in winter wheat as affected by crop sequence, intensity of tillage and time of herbicide application in a cool and humid climate

Summary There is a lack of information on the combined effects of preceding crop, reduced tillage (especially no-tillage) and the time of herbicide application on the development of weed populations and the efficiency of weed control in winter wheat in humid temperate climates. An experiment was conducted with a crop rotation (winter wheat – oilseed rape – winter wheat – maize) on a sandy loam and a loamy silt soil in the Swiss midlands to investigate the impact of different preceding crops and pre- and post-emergence control of weeds in conventional tillage (CT; mouldboard plough), minimum tillage (MT; chisel plough) and no-tillage (NT; no soil disturbance systems). When winter wheat was grown after maize and winter wheat was grown after oilseed rape, the ranking order of weed density in treatments without herbicide application was NT < MT < CT and CT < MT < NT respectively. Analysis of variance and canonical discriminant analysis showed that Epilobium spp., Sonchus arvensis , Myosotis arvensis and volunteer crops were more abundant in NT than in MT and CT. The efficiency of post-emergence weed control was generally better than that of pre-emergence weed control, regardless of tillage intensity.     

Effects of variation in rainfall on rainfed crop yields and water use in dryland farming areas in China

Crop production in the dryland farming areas of northern China is constrained by low and variable rainfall. This article presents the analysis of the relationships between variations in rainfall and yields of winter wheat and spring maize. The analysis is based on data from both several short-term and our ongoing long-term field experiments in dryland farming research projects in Tunliu, Linfen, Shouyang, and Luoyang. Grain yields of wheat and maize ranged from 1,548 to 5,169 and from 2,612 to 8,789 kg ha^-1 respectively, with differences up to above 200% (between dry and wet years). Wheat yields are sensitive to growing season rainfall but also correlated to water use (ET), whereas maize yields are sensitive to the critical time of water supply (especially June rainfall) but not correlated to ET. The ratio of grain yields to soil water at sowing is an important indicator, showing close relationships between yields and soil water-related ratio within the rainfed crops site. Comparison between the indices of water use efficiency (WUE) and precipitation use efficiency (PUE) suggests that the index WUE is more grain-related indicator than the PUE used for assessing rainfed crop water use by both maize and wheat. The index PUE should be used in caution, especially for wheat crops in dry years. Our results indicate that options to alleviate crop moisture stress must be tailored to the rainfall pattern. This holds especially for conservation tillage with response nutrient management practices that aim at enhancing water use efficiency.