Feasibility of Site-Specific Management of Corn Hybrids and Plant Densities in the Great Plains

The goal of this research was to determine the potential for use of site-specific management of corn hybrids and plant densities in dryland landscapes of the Great Plains by determining (1) within-field yield variation, (2) yield response of different hybrids and plant densities to variability, and (3) landscape attributes associated with yield variation. This work was conducted on three adjacent fields in eastern Colorado during the 1997, -98, and -99 seasons. Treatments consisted of a combination of two hybrids (early and late maturity) and four plant densities (24,692, 37,037, 49,382 and 61,727 plants ha^-1) seeded in replicated long strips. At maturity, yield was measured with a yield-mapping combine. Nine landscape attributes including elevation, slope, soil brightness (SB) (red, green, and blue bands of image), EC_a (shallow and deep readings), pH, and soil organic matter (SOM) were also assessed. An analysis of treatment yields and landscape data, to assess for spatial dependency, along with semi variance analysis, and block kriging were used to produce kriged layers (10 m grids). Linear correlation and multiple linear regression analysis were used to determine associations between kriged average yields and landscape attributes. Yield monitor data revealed considerable variability in the three fields, with average yields ranging from 5.43 to 6.39 Mg ha^-1 and CVs ranging from 20% to 29%. Hybrids responded similarly to field variation while plant densities responded differentially. Economically optimum plant densities changed by around 5000 plants ha^-1 between high and low-yielding field areas, producing a potential savings in seed costs of $6.25 ha^-1. Variability in yield across the three landscapes was highly associated with landscape attributes, especially elevation and SB, with various combinations of landscape attributes accounting for 47%, 95%, and 76% of the spatial variability in grain yields for the 1997, -98, and -99 sites, respectively. Our results suggest site-specific management of plant densities may be feasible.     

普通玉米杂交种高油化栽培效果研究

采用普通玉米杂交种或其同型雄性不育杂交种与高油玉米相间种植的方式,以提高普通玉米杂交种的产油量。结果表明,在高油115与普通杂交种农大108、雄性不育豫玉22号、雄性不育农大3138相间种植比例为2∶4、密度48 000株/hm2的条件下,普通玉米杂交种比高油玉米平均增产26.5%,比对照增产10.6%;雄性不育玉米杂交种比高油玉米增产25.2%,比对照增产31.6%;普通玉米杂交种、雄性不育杂交种和高油玉米的籽粒含油率平均为8.1%,8.1%和8.3%,而对照为4.2%~4.3%。     

Relationship Between Six Years of Corn Yields and Terrain Attributes

Crop yield, soil properties, and erosion are strongly related to terrain attributes. The objectives of our study were to examine the relationship between six years of corn (Zea mays L.) yield data and relative elevation, slope, and curvature, and to develop a linear regression model to describe the spatial patterns of corn yield for a 16 ha field in central Iowa, USA. Corn grain yield was measured in six crop years, and relative elevation was measured using a kinematic global positioning system. Slope and curvature were then determined using digital terrain analysis. Our data showed that in the four years with less than normal growing season precipitation, corn yield was negatively correlated with relative elevation, slope, and curvature. In the two years with greater than normal precipitation, yield was positively correlated with relative elevation and slope. A multiple linear regression model based on relative elevation, slope, and curvature was developed that predicted 78% of the spatial variability of the average yield of the transect plots for the four dry years. This model also adequately identified the spatial patterns within the entire field for yield monitor data from 1997, which was one of the dry years. The relationship between terrain attributes and corn yield spatial patterns may provide opportunities for implementing site-specific management.     

9个糯玉米自交系产量及其主要产量性状的配合力分析

试验选用9份不同来源的鲜食糯玉米自交系,按照Griffi ng完全双列杂交方法Ⅳ组配出36份杂交组合,对所获得的杂交组合产量及其主要产量性状进行配合力分析。结果表明:W6、W9、W4、W3、W1等5个糯玉米自交系产量一般配合力较高,可以组配出产量较高的杂交种后代,其中产量特殊配合力(SCA)值最大的组合是W4×W7(90.377 8);自交系W1、W3、W6、W4等4个自交系可以组配出果穗较粗、穗行数较多的杂交组合;自交系W3、W7、W9等3个自交系作为亲本组配杂交组合,易获得果穗较长、秃尖较小、行粒数较多糯玉米杂交品种;W6、W9、W1、W8等4个自交系,用作亲本组配杂交种可以较明显地提高子代百粒重,有利于高产品种的育成;自交系W4、W6、W3、W2等4个自交系作为亲本可以组配出出籽率较高的杂交种后代。     

Spatial and Temporal Variability of Corn Grain Yield: Site-Specific Relationships of Biotic and Abiotic Factors

Inadequate information on factors affecting crop yield variability has contributed to the slow adoption of site-specific farming (SSF). This study was conducted to determine the effects of biotic and abiotic factors on the spatial and temporal variability of irrigated corn grain yields and to derive information useful for SSF. The effects of water (80% evapotranspiration (ET) and 50% ET), hybrid (drought-tolerant and -susceptible), elevation, soil index (SI)(texture), soil NO₃–N, arthropods, and diseases on corn grain yield were investigated at Halfway, TX on geo-referenced locations. Grain yields were influenced by interrelationships among biotic and abiotic factors. Grain yields were consistently high under high water treatment, at higher elevations, and on soils with high SI (high clay and silt). Soil NO₃–N increased grain yields when water was adequate. Management zones for variable rate fertilizer and water application should, therefore, be based on information on elevation, SI, and soil NO₃–N. The effects of arthropods, diseases, and crop stress (due to drought and N) on corn grain yield were unpredictable. Spider mite (Oligonychus pratensis) and common smut (Ustilago zeae) damage occurred under hot and dry conditions in 1998. Spider mite infestations were high in areas with high soil NO₃–N. Moderate air temperatures and high relative humidity in 1999 favored southwestern corn borer (Diatraea grandiosella) and common rust (Puccinia maydis) incidences. Knowledge of conditions that favor arthropods and diseases outbreak and crop stress can improve the efficiency of scouting and in-season management of SSF. Management of SSF can be improved when effects of biotic and abiotic factors on grain yield are integrated and evaluated as a system.     

Identifying important factors influencing corn yield and grain quality variability using artificial neural networks

Soil, landscape and hybrid factors are known to influence yield and quality of corn (Zea mays L.). This study employed artificial neural network (ANN) analysis to evaluate the relative importance of selected soil, landscape and seed hybrid factors on yield and grain quality in two Illinois, USA fields. About 7 to 13 important factors were identified that could explain from 61% to 99% of the observed yield or quality variability in the study site-years. Hybrid was found to be the most important factor overall for quality in both fields, and for yield as well in Field 1. The relative importance of soil and landscape factors for corn yield and quality and their relationships differed by hybrid and field. Cation exchange capacity (CEC) and relative elevation were consistently identified as among the top four most important soil and landscape factors for both corn yield and quality in both fields in 2000. Aspect and Zn were among the top five most important factors in Fields 1 and 2, respectively. Compound topographic index (CTI), profile curvature and tangential curvature were, in general, not important in the study site-years. The response curves generated by the ANN models were more informative than simple correlation coefficients or coefficients in multiple regression equations. We conclude that hybrid was more important than soil and landscape factors for consideration in precision crop management, especially when grain quality was a management objective.     

Is the Soil Variability within the Small Fields of Flanders Structured Enough to Allow Precision Agriculture?

The average area of agricultural fields in Flanders (Belgium) is about 1.7 ha, being very small compared to fields where precision agriculture is currently applied. Therefore this paper addresses the question whether the within-field variation of soil properties in such fields is structured enough to motivate precision agriculture. To answer this question, 9 soil properties determined on 380 soil samples located in 77 agricultural fields situated in the 5 most dominant pedoscapes of Flanders were used to analyze their spatial variation over intervals ranging from 5 to 900 m. The data set was subjected to a principal component analysis which identified two principal components (PCs) explaining more than 78% of the total variance. The first PC represented the chemical soil properties and the second the physical and biological properties. A variogram analysis of the scores on these two PCs showed that the micro-scale and random variation dominated (82%) the within-field variability of the first PC. The within-field variability of the second PC was dominantly spatially structured (only 37% micro-scale and random variation). Therefore, it was concluded that mainly for soil physical and biological properties (like soil textural fractions and organic matter), the average within-field variation in the small fields of the investigated landscapes is structured enough to allow precision agriculture.     

Are precision agriculture tools and methods relevant at the whole-vineyard scale?

Precision viticulture (PV) has been mainly applied at the field level, for which the ability of high resolution data to match within-field variability has been already shown. However, the interest of PV for grape growers would be greater if its principles could also apply at a larger scale, as most growers still focus their management on a multi-field scale, not considering each field as an isolated unit. The aim of this study was to analyse whether it is possible and relevant to use PV tools to define meaningful management zones at the whole-vineyard scale. The study was carried out on a 90-ha vineyard made of 27 contiguous fields. The spatial variability of vine vigour, estimated with the Normalized Difference Vegetation Index (NDVI), was analysed at within-field and whole-vineyard scales. The spatial variability of the vigour was significant and spatially organized whatever the considered scale. Besides, vineyard spatial variability was characterised using information on environmental factors (soil apparent conductivity and elevation) and vine response (yield, vigour and grape composition). At both scales, NDVI and measured environmental factors were used to establish a three-level classification, whose agronomic significance was tested comparing the vine response observed for each class. The analysis of high resolution information allowed the definition of classes with agronomic and oenological implications, although there was not a straightforward correspondence between the classes defined and quality. Analysing the variability at the whole-vineyard scale highlighted a trend of spatial variation associated to elevation that was hardly visible at the within-field level.     

高产夏玉米镁的吸收与再分配研究

本文就高产条件下两种株型夏玉米在不同生育时期对镁的吸收、积累及镁在不同器官间的分配与再分配进行了分析。结果表明，玉米植株相对含镁量在一生中基本呈现前期高、后期低的变化趋势。植株吸收的镁在吐丝前主要分配到叶片、茎秆和叶鞘中，吐丝后镁的分配重点则转向籽粒。玉米对镁的吸收有２个高峰期，平展型品种分别在拔节至大喇叭口期和籽粒形成期；紧凑型品种分别在大喇叭口至吐丝期和灌浆始期。每形成百公斤籽粒吸收镁０．３８２～０．３９７ｋｇ。籽粒中的镁有３７．０６％～４４．０５％来自于其它器官镁的再分配。平展型品种向籽粒转移镁最多的器官是叶鞘和叶片，紧凑型品种向籽粒转移镁最多的器官是叶鞘、雄穗和叶片。     

不同类型玉米杂交种产量潜力及配套栽培措施的研究

采用L_9(3~4)正交设计,研究了中长穗、耐密植型和平展叶、大穗型两类玉米杂交种的产量潜力和配套栽培措施。结果表明:中长穗、耐密植型杂交种(掖单6号、掖单13号等)具有较高的产量潜力。表现在适于密植(4500—6000/亩)且个体生产能力强,对肥料反应敏感。而平展叶、大穗型杂交种不仅不耐密植(2800—3800/亩)而且对肥料反应迟钝,增产潜力不大。本研究提出了两类杂交种的最优处理组合以及不同杂交种的优化配套栽培措施,并对我省玉米杂交种的选用,不同杂交种的适宜密度以及配方施肥等问题进行了讨论。     

鲜食糯玉米单交种"津农(糯)2"选育报告

介绍了鲜食糯玉米单交种津农(糯)2的选育过程,研究了该品种的产量形状、品种特性和适宜种植区域。结果表明,津农(糯)2具有高产、优质、抗逆性较强、生态适应性广等特点,可作为鲜食玉米在国内多数地区推广种植。     

Soil Sampling Techniques for Alabama,USA Grain Fields

Characterizing the spatial variability of nutrients facilitates precision soil sampling. Questions exist regarding the best technique for directed soil sampling based on a priori knowledge of soil and crop patterns. The objective of this study was to evaluate zone delineation techniques for Alabama grain fields to determine which method best minimized the soil test variability. Site one (25.8 ha) and site three (20.0 ha) were located in the Tennessee Valley region, and site two (24.2 ha) was located in the Coastal Plain region of Alabama. Tennessee Valley soils ranged from well drained Rhodic and Typic Paleudults to somewhat poorly drained Aquic Paleudults and Fluventic Dystrudepts. Coastal Plain soils ranged from coarse-loamy Rhodic Kandiudults to loamy Arenic Kandiudults. Soils were sampled by grid soil sampling methods (grid sizes of 0.40 ha and 1 ha) consisting of: (1) twenty composited cores collected randomly throughout each grid (grid-cell sampling) and, (2) six composited cores collected randomly from a 3×3m area at the center of each grid (grid-point sampling). Zones were established from (1) an Order 1 Soil Survey, (2) corn (Zea mays L.) yield maps, and (3) airborne remote sensing images. All soil properties were moderately to strongly spatially dependent as per semivariogram analyses. Differences in grid-point and grid-cell soil test values suggested grid-point sampling does not accurately represent grid values. Zones created by soil survey, yield data, and remote sensing images displayed lower coefficient of variations (%CV) for soil test values than overall field values, suggesting these techniques group soil test variability. However, few differences were observed between the three zone delineation techniques. Results suggest directed sampling using zone delineation techniques outlined in this paper would result in more efficient soil sampling for these Alabama grain fields.     

鲜食糯玉米单交种津农1选育报告

介绍了鲜食糯玉米杂交种津农1的选育过程,研究了该品种的产量性状、品种特性和适宜种植的区域。结果表明,津农1具有高产、优质、抗逆性强、生态适应性好等特点,可作为鲜食玉米在国内大多数地区推广种植。     

旱作地膜玉米密植增产用水效应及土壤水分时空变化

【目的】干旱缺水是黄土高原旱作农业最大的限制因素,研究覆膜、增密和品种对旱作玉米增产和水分利用的影响,有助于揭示未来旱作粮食持续增产与水环境的关系。【方法】试验于2012—2015年在黄土高原丘陵沟壑区的宁夏彭阳进行,在全膜双垄沟(FPRF)和半膜平铺盖(HPFC)2种种植方式下,选择耐密中晚熟先玉335和吉祥1号及不耐密早熟酒单4号3个杂交种,低密度(4.5万株/hm~2)、中密度(6.75万株/hm~2)和高密度(9.0万株/hm~2)3个水平,随机区组设计,玉米连作定位观测。采用烘干法监测不同降水年型玉米生育时期0—200 cm土层土壤水分,通过Surfer软件绘制土壤水分等值线图,研究旱作覆膜连作玉米产量、水分利用效率(WUE)及土壤水分时空变化。【结果】在地膜覆盖条件下各因素对旱作玉米产量和水分利用的影响达到极显著或显著水平,对籽粒产量和WUE的影响顺序依次为降水年型密度覆膜方式品种,降水年型从干旱、正常、丰水年的变化,玉米产量由7.72和8.79 t·hm~(-2)增加到11.86和11.15 t·hm~(-2),但WUE最高值并不在降水较多的年份,而在正常年型。密度由4.5万株/hm~2增加到6.67万株/hm~2,耗水量、产量、WUE增加10.6 mm、20.0%和3.45 kg·mm~(-1)·hm~(-2),但密度从6.67万株/hm~2增加到9.0万株/hm~2时,耗水量不再增加,而产量和WUE提高12.0%和2.97 kg·mm~(-1)·hm~(-2);FPRF处理较HPFC处理平均增产15.72%,WUE提高21.09%;耐密中晚熟品种吉祥1号和先玉335较耐密性弱早熟品种酒单4号增产15.46%—24.45%,WUE提高13.35%—15.55%。在全膜双垄沟种植条件下,玉米生育期内土壤剖面水分含量始终高于半膜平覆盖种植,尤其是玉米灌浆期0—200 cm土层多蓄积了50—90 mm的土壤水分,在严重伏旱年份发挥了明显的抗旱增产作用。不论降雨年型如何,4年期间全膜双垄沟播玉米产量增加和WUE提高并没有多消耗土壤水分,土壤深层未形成低湿层,也未观察到增密增产对土壤剖面水分循环的负效应,而干旱年份半膜平铺盖形成了一个土壤水分8%的明显干土层,并且随着玉米生长时间的推后干土层厚度增加、范围扩大。【结论】在目前地膜覆盖和生产平均密度5.3万株/hm~2基础上,"全膜双垄沟播+耐密品种+增密1.5万株/hm~2"是年降雨450 mm以上旱作区玉米持续增产和水分高效利用的技术关键,增密增产不会导致土壤深层形成干土层。     

Airborne Videography to Identify Spatial Plant Growth Variability for Grain Sorghum

Much research has focused on the use of intensive grid soil sampling and yield monitors to identify within-field spatial variability in precision farming. This paper reports on the use of airborne videography to identify spatial plant growth patterns for grain sorghum. Color-infrared (CIR) digital video images were acquired from two grain sorghum fields in south Texas several times during the 1995 and 1996 growing seasons. The video images were registered, and classified into several zones of homogeneous spectral response using an unsupervised classification procedure. Ground truthing was performed upon a limited number of sites within each zone to determine plant density, plant height, leaf area index, biomass, and grain yield. Results from both years showed that the digital video imagery identified within-field plant growth variability and that classification maps effectively differentiated grain production levels and growth conditions within the two fields. A temporal comparison of the images and classification maps indicated that plant growth patterns differed somewhat between the two successive growing seasons, though areas exhibiting consistently high or low yield were identified within each field.     

玉米秸秆还田对土壤性状及玉米生长的影响

[目的] 探索玉米秸秆还田对土壤物理性状、培肥效果、玉米生长及产量的影响。[方法] 本试验设秸秆还田+施肥、秸秆还田+不施肥、秸秆不还田+施肥、秸秆不还田+不施肥4个处理,通过定期取样测定不同处理的土壤田间持水量、全氮、碱解氮、有效磷、速效钾等指标,对土壤容重、有机质等理化性状进行分析,定期调查玉米生长动态指标,最后测产和考种。[结果] 秸秆还田区与不还田区相比较,土壤容重降低、土壤有机质等养分含量和玉米产量增加。反映出秸秆还田在改善土壤理化性状、提高土壤肥力、促进玉米生长和增加产量等方面有着显著效果,因此,玉米秸秆还田对土壤性状和玉米生长的影响具有重要的意义。同时具有稳产、高效、环保等优点,是一项较佳的培肥地力和增产措施,可在大方县玉米种植地区加以广泛推广。     

糯玉米新品种陕白糯11的选育研究

糯玉米陕白糯11是西北农林科技大学农学院专用玉米研究室,1998年用自选系Y89作母本,自选系Y90为父本杂交育成。经过2002—2004年陕西省糯玉米区试。2004年省特用玉米生产试验,表现出籽粒容重749g/L,粗蛋白10.91%,粗脂肪5.41%,粗淀粉70.08%,支链淀粉占粗淀粉99.49%,赖氨酸含量0.31%,鲜食穗感官及蒸煮加工品质评分90,达到国家糯玉米一级指标,三年区试16点次11点增产5点次减产,干籽率产量6238.5kg/hm2较中糯1号增产20.3%,抗倒,农艺性状优良,可作速冻加工、鲜食上市或专用淀粉加工的原料,2005年3月7日通过陕西省第36次农作物品种审定委员会审定推广。     

紫甜玉米产量及其构成因素和品质性状的杂种优势和配合力分析

【目的】对20个紫甜玉米自交系与2个测试种进行产量及其构成因素和品质性状的杂种优势和配合力分析,为高效创制高产甜玉米自交系提供材料基础和理论依据。【方法】将20个紫甜玉米自交系（TD01~TD20）与2个测试种[黄色甜玉米自交系（TI）和白色甜玉米自交系（T2）]进行杂交组配,采用完全随机组设计对获得的40个杂交组合（TH01~TH40）进行田间试验,以SW1011和Fancy 111为对照品种。测定亲本及其杂交组合的产量及其构成因素和品质性状。利用Line×Tester模型在AGD-R软件中进行中亲优势度（Hm）、杂种优势度（Hb）和一般配合力（GCA）分析。【结果】紫色种皮由父本遗传,在40个杂交组合中占优势,所有测定的性状表现为中亲优势和杂种优势。大多数亲本系鲜穗收获期的Hm、Hb和GCA表现为负值,说明这些亲本系具有组配早熟杂交种的潜力。除收获期和穗粗外,其余调查性状表现出多个显性效应,证明了非加性遗传效应的重要性。具有较高GCA的杂交组合为TH05（T1×TD05）、TH31（T2×TD11）、TH20（T1×TD20）、TH33（T2×TD13）、TH34（T2×TD14）、TH16（T1×TD16）、TH08（T1×TD08）和TH25（T2×TD05）。【结论】紫色甜玉米与黄色甜玉米自交系或白色甜玉米自交系杂交,紫色性状具有显性效应,筛选出的8个品质优良杂交种及其亲本可作为培育越南商品化紫甜玉米品种的亲本材料。     

高油玉米三利用技术的研究

试验以不育农大108×高油5580、不育农大108×高油6528、不育农大108×高油4515、不育潞玉13×高油5580、不育潞玉13×高油6528、不育潞玉13×高油4515为材料对普通玉米高油化三利用技术进行研究。不育普通玉米和高油授粉者种植行比为3∶1和3∶3。试验得到以下结果:6个组合杂交当代子粒油分含量增加明显,说明利用普通玉米高油化模式可改进普通玉米品质;以不育农大108普通玉米为母本有一组合产量增加幅度较大,但油分增加幅度不大,说明组合选择较合理,但种植行比还有一定的空间;以不育潞玉13为母本的组合产量和油分均增加,说明不育潞玉13可作为当地高油玉米三利用技术的主推品种。     

鲜食玉米杂交种津鲜糯105选育研究

介绍了鲜食糯玉米杂交种津鲜糯105的选育过程,研究了该品种的产量性状、品种特性和适宜种植区域。结果表明,津鲜糯105具有高产、优质、抗逆性强、生态适应性好等特点,作为鲜食玉米可在国内多数地区种植。