Influence of fly ash and sewage sludge application on wheat biomass production,nutrients availability,and soil properties

The influence of fly ash(FA)applied alone and/or with sewage sludge(SS)on wheat(Triticum vulgare)grain yield,biomass production and soil properties was studied in a field experiment.The results showed that both FA and SS significantly increased grain yield and plant biomass.FA applied alone increased significantly soil pH and EC while FA applied together with SS did not significantly affect them compared to mono FA treatment.Soil pH and EC values increased with time in FA and FA-SS treatments.SS increased soil organic matter and total N content and SS applied together with FA increased also available soil B.From the plant nutrients tested only tissue N concentration was increased significantly in all treatments compared to control.Copper,Zn,Mn,Ni,and Pb at both available and total concentrations are significantly affected.

Impacts and uncertainty analysis of elevated temperature and CO_2 concentration on wheat biomass

Impacts of climatic change on agriculture and adaptation are of key concern of scientific research. However, vast uncertainties exist among global climates model output, emission scenarios, scale transformation and crop model parameterization. In order to reduce these uncertainties, we integrate output results of four IPCC emission scenarios of A1 FI, A2, B1 and B2, and five global climatic patterns of HadCM3, PCM, CGCM2, CSIRO2 and ECHAM4 in this study. Based on 20 databases of future climatic change scenarios from the Climatic Research Unit （CRU） , the scenario data of the climatic daily median values are generated on research sites with the global mean temperature increase of 1℃（GMT＋ID）, 2℃（GMT＋2D） and 3℃（GMT＋3D）. The impact of CO2 fertilization effect on wheat biomass for GMT＋I D, GMT＋2D and GMT＋3D in China＇s wheat-producing areas is studied in the process model, CERES-Wheat and probabilistic forecasting method. The research results show the CO2 fertilization effect can compensate reduction of wheat biomass with warming temperature in a strong compensating effect. Under the CO2 fertilization effect, the rain-fed and irrigated wheat biomasses increase respectively, and the increment of biomass goes up with temperature rising. The rain-fed wheat biomass increase is greater than the irrigated wheat biomass. Without consideration of CO2 fertilization effect, both irrigated and rain-fed wheat biomasses reduce, and there is a higher probability for the irrigated wheat biomass than that of the rain-fed wheat biomass.

Estimation of biomass in wheat using random forest regression algorithm and remote sensing data

Wheat biomass can be estimated using appropriate spectral vegetation indices.However,the accuracy of estimation should be further improved for on-farm crop management.Previous studies focused on developing vegetation indices,however limited research exists on modeling algorithms.The emerging Random Forest(RF) machine-learning algorithm is regarded as one of the most precise prediction methods for regression modeling.The objectives of this study were to(1) investigate the applicability of the RF regression algorithm for remotely estimating wheat biomass,(2) test the performance of the RF regression model,and(3) compare the performance of the RF algorithm with support vector regression(SVR) and artificial neural network(ANN) machine-learning algorithms for wheat biomass estimation.Single HJ-CCD images of wheat from test sites in Jiangsu province were obtained during the jointing,booting,and anthesis stages of growth.Fifteen vegetation indices were calculated based on these images.In-situ wheat above-ground dry biomass was measured during the HJ-CCD data acquisition.The results showed that the RF model produced more accurate estimates of wheat biomass than the SVR and ANN models at each stage,and its robustness is as good as SVR but better than ANN.The RF algorithm provides a useful exploratory and predictive tool for estimating wheat biomass on a large scale in Southern China.

Effects of Light and Temperature Factors on Biomass Accumulation of Winter Wheat

[Objective] The study aimed to discuss the influence of light and temperature factors on biomass accumulation of winter wheat at each growth stage and changes in biomass of each organ. [Method] Based on the observation data from Xifeng Agrometeorological Experiment Station of Gansu Province, including phenophase and yield factors of winter wheat in 1981 -2008, biomass at three-leaves, overwintering, jointing, heading, milky maturity, and maturity stages in 1995 -2008, and meteorological data in 1995 -2008, the variation patterns of the biomass accumulation and the influence of TEP （thermal effectiveness photosynthetically active radiation） on the biomass of winter wheat at every growth stage were ana- lyzed. [Result] The biomass accumulation of winter wheat in the whole growth period presented ＂S＂ curve, with the maximum value from heading to milky maturity stage. Since 1981, TEP from heading to milky maturity stage increased with a rate of 3. 314 MJ/（m2 · a）, and the changing curves of TEP at other stages were like parable curves. TEP from turning green to jointing stage and from milky maturity to maturity stage had a higher value in the 1990s and a lower val.ue in the 1980s and early 21st century, while that from jointing to heading stage had a lower value in the 1990s but a higher value in the 1980s and early 21st century. There was a significant correlation between TEP at each growth stage and the actual yield. LAI （leaf area index） at each development stage also had a significant correlation with the utilization rate of TEP at corresponding stage. When LAI at jointing and heading stages increased by I, the utilization rate of TEP correspondingly increased by 0. 049 and 0.259 g/MJ respectively. [ Conclusion] The research could provide theoretical references for the scientific planting and management of winter wheat in future. Key words Light and temperature factors; Winter wheat; Biomass; Influence; China

Impacts and uncertainty analysis of elevated temperature and CO2 concentration on wheat biomass

Impacts of climatic change on agriculture and adaptation are of key concern of scientific research. However, vast uncertainties exist among global climates model output, emission scenarios, scale transformation and crop model parameterization. In order to reduce these uncertainties, we integrate output results of four IPCC emission scenarios of A1FI, A2, B1 and B2, and five global climatic patterns of HadCM3, PCM, CGCM2, CSIRO2 and ECHAM4 in this study. Based on 20 databases of future climatic change scenarios from the Climatic Research Unit (CRU) , the scenario data of the climatic daily median values are generated on research sites with the global mean temperature increase of 1 ℃(GMT+1D), 2 ℃ (GMT+2D) and 3 ℃(GMT+3D). The impact of CO2 fertilization effect on wheat biomass for GMT+1D, GMT+2D and GMT+3D in China’s wheat-producing areas is studied in the process model, CERES-Wheat and probabilistic forecasting method. The research results show the CO2 fertilization effect can compensate reduction of wheat biomass with warming temperature in a strong compensating effect. Under the CO2 fertilization effect, the rain-fed and irrigated wheat biomasses increase respectively, and the increment of biomass goes up with temperature rising. The rain-fed wheat biomass increase is greater than the irrigated wheat biomass. Without consideration of CO2 fertilization effect, both irrigated and rain-fed wheat biomasses reduce, and there is a higher probability for the irrigated wheat biomass than that of the rain-fed wheat biomass.

大气NH_(3)浓度升高和施氮对冬小麦生物量和氮素利用的影响

为揭示大气NH_(3)浓度升高和施氮对冬小麦生物量和氮素利用的影响,通过开顶式气室,以小偃22为试验材料,于2020-2022两年进行田间微区试验,设置3个施氮水平(0、180和240 kg·hm^(-2))和两种大气NH_(3)浓度(空气背景NH_(3)浓度:0.01~0.03 mg·m^(-3);高NH_(3)浓度:0.30~0.60 mg·m^(-3)),对不同处理下小麦地上部和根系干物质、氮素积累量及氮素利用效率进行分析。结果表明,大气NH_(3)浓度升高能显著提升小麦地上部生物量、根系生物量、地上部氮素积累量和根系氮素积累量,2年内平均增幅分别为5.77%、6.74%、8.94%和9.98%。在空气背景NH_(3)浓度下,施氮后小麦显著增产,180和240 kg·hm^(-2)施氮水平下产量较0 kg·hm^(-2)施氮水平分别提高了45.26%和50.67%。在大气NH_(3)浓度升高环境中,随着施氮量的增加,小麦产量出现先升后降趋势,180 kg·hm^(-2)施氮水平下产量最高,240 kg·hm^(-2)施氮水平下小麦产量较0 kg·hm^(-2)施氮水平降低17.97%,小麦氮肥农学效率和氮素利用率也随之降低。这说明,大气NH3浓度升高的环境中适当减少氮肥施用量能有效提升冬小麦的氮素利用率,稳定小麦产量。

Control of Common Chickweed in Winter Wheat with Postemergence Herbicides

A total of six experiments were conducted over a two-year period (2018, 2019) at the University of Guelph Ridgetown Campus to assess the efficacy of various herbicides applied postemergence (POST) for the control of common chickweed in winter wheat. Fluroxypyr/bromoxynil/MCPA, pyrasulfotole/bromoxynil,pyrasulfotole/bromoxynil/fluroxypyr,pyrasulfotole/bromoxynil/thiencarbazone, pyrasulfotole/bromoxynil/thiencarbazone + MCPA ester, tolpyralate and fluroxypyr/halauxifen + MCPA EHE, applied POST, controlled common chickweed only 5% - 42% at 2 weeks after treatment (WAT) and 1% - 23% at 4 WAT and resulted in common chickweed density and biomass that was similar to non-treated weedy control. Fluroxypyr/halauxifen + pyroxsulam + MCPA EHE, applied POST, provided 57% - 82% control of common chickweed and reduced density 93% and biomass 98% compared to the non-treated control. Thifensulfuron/tribenuron, thifensulfuron/tribenuron + MCPA ester, thifensulfuron/tribenuron + fluroxypyr + MCPA ester, tribenuron + thiencarbazone, and tribenuron + thiencarbazone + MCPA ester, applied POST, controlled common chickweed 98% - 100% and reduced common chickweed density 96% - 98% and common chickweed biomass 99%. Based on these results, herbicide treatments which contained tribenuron including thifensulfuron/tribenuron, thifensulfuron/tribenuron + MCPA ester, thifensulfuron/tribenuron + fluroxypyr + MCPA ester, tribenuron + thiencarbazone, and tribenuron + thiencarbazone + MCPA ester were the most efficacious for the control of common chickweed in wheat. In addition, fluroxypyr/halauxifen + pyroxsulam + MCPA EHE, applied POST, can provide adequate control of common chickweed in winter wheat.

Growth traits and nitrogen assimilation-associated physiological parameters of wheat(Triticum aestivum L.) under low and high N conditions

In this study, 14 wheat cultivars with contrasting yield and N use efficiency （NUE） were used to investigate the agronomic and NUE-related traits, and the N assimilation-associated enzyme activities under low and high N conditions. Under deficient-N, the cultivars with high N uptake efficiency （UpE） and high N utilization efficiency （UtE） exhibited higher plant biomass, yields, and N contents than those with medium and low NUEs. The high UpE cultivars accumulated more N than other NUE type cultivars. Under sufficient-N, the tested cultivars showed similar patterns in biomass, yield, and N content to those under deficient-N, but the varietal variations in above traits were smaller. In addition, the high UpE cultivars displayed much more of root biomass and larger of root length, surface area, and volume than other NUE type cultivars, indicating that the root morphological traits under N deprivation are closely associated with the plant biomass through its improvement of the N acquisition. The high UtE cultivars showed higher activities of nitrate reductase （NR）, nitrite reductase （NIR）, and gluta- mine synthetase （GS） at stages of seediling, heading and filling than other NUE type cultivars under both low and high N conditions. Moreover, the high UpE and UtE cultivars also displayed higher photosynthetic rate under deficient-N than the medium and low NUE cultivars. Together, our results indicated that the tested wheat cultivars possess dramatically genetic variations in biomass, yield, and NUE. The root morphological traits and the N assimilation enzymatic acitivities play critical roles in regulating N accumulation and internal N translocation under the N-starvation stress, respectively. They can be used as morphological and biochemical references for evaluation of UpE and UtE in wheat.

长期施用有机肥对半干旱区春小麦产量及其水分利用效率和土壤有机碳的影响

以国家土壤质量安定观测试验站黄绵土区的农田长期定位试验为研究对象,研究长期施用有机肥对半干旱区春小麦产量及其水分利用效率和有机碳的影响。结果表明,连续种植7年春小麦,施肥显著影响小麦产量及其水分利用效率,以化肥与有机肥配施(NPKM)处理效果最好,较单施化肥(NPK)、单施有机肥(OM)处理春小麦产量和水分利用效率分别增加了7.18%和7.82%、5.91%和3.83%;在定位施肥初期(前3年),NPKM和NPK处理的效果优于OM,在第4年三者无差异,而第5年及之后,NPKM和OM处理的效果明显好于NPK处理。长期NPKM和OM处理较NPK处理0~20 cm土层土壤有机碳含量分别显著增加了36.88%和31.98%,有机碳储量分别显著增加了31.17%~41.94%和27.80%~35.81%,表层0~10 cm的增加效果显著好于10~20 cm土层。不同施肥处理对0~20 cm土层土壤微生物生物量碳(MBC)的影响表现为NPKM>OM>NPK>CK,且差异显著,长期NPKM和OM处理较NPK处理土壤MBC分别显著增加了46.4%和28.7%,长期单施NPK处理可显著增加土壤MBC含量,但对有机碳影响不明显。综上所述,长期NPKM或OM处理可显著增加黄绵土小麦地土壤有机碳和MBC含量,增加有机碳储量,有利于农田土壤固碳增汇,提高小麦产量及其水分利用效率。

大气CO_(2)浓度升高背景下冬小麦冠层光谱特征和地上生物量估算

本研究旨在探究大气CO_(2)浓度升高对冬小麦全生育时期冠层光谱特征的影响,并基于筛选的敏感波段建立地上生物量(AGB)与光谱参数的定量关系。为此,在2021—2022年的冬小麦生长季,利用开放式CO_(2)富集系统(Mini-FACE),设定大气CO_(2)浓度(ACO_(2),(420±20)μL L^(–1))和高CO_(2)浓度(ECO_(2),(550±20)μL L^(–1))两个处理水平,分析了高CO_(2)浓度下光谱特征变化,基于连续投影算法(SPA)、逐步多元线性回归(SMLR)和偏最小二乘法回归(PLSR)筛选AGB敏感波段并构建估算模型。结果表明:CO_(2)浓度升高使冬小麦拔节期和开花期AGB显著增加。红边和近红边反射率及红边面积在拔节期增加,在开花期和灌浆期降低,蓝边、黄边和红边位置在不同生育时期均发生移动;AGB的敏感光谱波段主要分布在红边和近红边区域,CO_(2)浓度升高缩小了AGB敏感波段范围,但不影响AGB的估算;AGB的SMLR和PLSR模型均取得了较高的估算精度(R^(2)>0.8),其中SMLR模型中的R_(799′)、D_(y)、SD_(y)和PRI等特征参数与AGB显著相关,R^(2)为0.866。PLSR模型(R^(2)>0.9)在估算精度和稳定性上优于SMLR模型。本研究可为未来高CO_(2)浓度下冬小麦生长发育的遥感监测提供理论基础和技术方法。

不同钝化剂对镉污染小麦镉富集及产量的影响

为实现河套灌区轻中度Cd污染农田的修复与安全利用,在河套灌区轻中度Cd污染农田开展了为期两年不同钝化剂处理的大田试验,7种钝化剂分别为生物炭(BC)、海泡石(SEP)、膨润土(BE)、坡缕石(PA)、腐植酸(HA)、硅酸钠(SS)、硫酸锰(MN),以不施用钝化剂为对照(CK),分析了不同处理下小麦产量、生物量、各器官Cd富集系数和转运系数,比较了不同钝化剂的钝化效果。结果表明,2020-2021年,SEP和SS处理较CK增产显著,增幅为11.09%~81.49%,各器官生物量均有不同程度的增加,其中籽粒及根增加显著;SS处理显著降低叶部Cd含量,降幅为26.75%,SEP处理显著降低籽粒Cd含量,降幅达47.62%。钝化剂处理下,各部位Cd富集系数均<1,根部到叶部Cd最高。小麦籽粒Cd含量与茎中Cd富集系数呈极显著的正相关,与茎向叶部、根向穗部的Cd转运系数呈显著的正相关;2年茎的Cd富集系数对籽粒Cd富集系数均有显著正效应,穗到籽粒、茎到叶的Cd转运系数对籽粒Cd富集系数影响最大。海泡石和硅酸钠处理增加了小麦产量,降低了植株Cd含量,抑制了Cd在植株体内的转运富集;内蒙古河套灌区轻中度Cd污染农田,推荐施用硅酸钠和海泡石进行小麦安全生产。

水肥添加对草田轮作系统土壤呼吸速率的影响

土壤呼吸是生态系统碳排放最重要的途径,其微小变化将对陆地生态系统碳循环产生深远的影响。为探究不同管理方式对草田轮作系统土壤碳排放的影响,本研究开展水肥添加控制试验,动态监测紫花苜蓿(Medicago sativa L.)-冬小麦(Triticum aestivum L.)草田轮作系统中冬小麦阶段的土壤呼吸速率、土壤微生物生物量碳/氮含量、土壤温度和土壤含水量等指标。结果显示水分添加使土壤呼吸速率提高28.5%(P<0.05),但肥料添加对其影响不显著。水分添加使土壤含水量提高24.7%,但使土壤温度降低9.7%;肥料添加使土壤温度降低11.0%,使0~10 cm, 10~20 cm土层土壤微生物生物量氮含量提高336%,131%。本研究说明水肥添加通过影响土壤温度、土壤含水量等土壤质量指标,影响植物根系生长发育和微生物活性,最终影响草田轮作系统土壤碳排放。

不同施肥措施对高纬地区小麦生长和氮肥利用率的影响

为揭示不同施肥措施对高纬地区小麦生长及氮肥利用率的影响。选取内蒙古呼伦贝尔为研究区,采用野外观测和室内测定相结合的方式,研究了2种缓释肥和1种缺氮处理对高纬地区小麦生长及氮肥利用率的影响。结果表明,含有腐殖质的缓释肥对地上生物量的作用最大,增产了4.93%,使小麦产量增产了1.77%,含腐殖质的缓释肥提高了氮肥贡献率和氮肥农学效率,分别为8.71%和5.48 kg/kg,缺氮处理对小麦地上干生物量副作用最大,较常规施肥减产了4.9%。说明含腐殖质的缓释肥可有效促进高纬地区小麦的生产和提高氮肥利用率。

不同降水年型下旱地春小麦产量及其构成因素对播期和日均温度变化响应的模拟分析

为探讨播期调控及降水量和日均温度变化对旱地春小产量及其构成因素的耦合效应,基于甘肃省陇中地区气象数据、土壤数据和管理数据,通过APSIM模型对不同播期及日均温度变化情景下春小麦产量和生物量进行模拟分析,并利用试验区2013-2018年大田试验的春小麦产量及生物量数据对该模型进行适用性验证。结果表明,春小麦模拟产量及生物量的NRMSE均在8%以内,模型的有效性均大于0.80,说明模型具有较高的准确度和适用性。使用1970-2018年研究区的气象及土壤数据,设置不同播期及日均温度变化的模拟情景[早播(3月3日)、正常播(3月18日)、晚播(3月31日);日平均温度变化范围为降温2.0℃~增温2.0℃,以温度变化量1℃为1个梯度],经回归分析,小麦产量受影响程度表现为降水量>温度>播期,相同气候条件下小麦产量均表现为正常播>早播>晚播。春小麦在湿润年、正常播、日均温度降低2.0℃的条件下可获得最高产量。降水量对春小麦千粒重和籽粒数分别表现出负效应和正效应,温度则分别表现出正效应和负效应,千粒重和籽粒数均随着播期的推迟先增加后减少。综合分析,降水增多可通过增加春小麦籽粒数来提高产量;当地春小麦宜在3月中旬播种且应注重防寒与蓄水保墒,以促进小麦的高产与稳产。

外源褪黑素对小麦缓解土壤铜胁迫的影响

采用盆栽试验,设置对照(CK)、MT1(100μmol·L^(-1))、MT2(500μmol·L^(-1))和MT3(1000μmol·L^(-1))4个不同水平褪黑素处理,褪黑素采用浸种(24 h)方式施用,研究Cu胁迫(150 mg·kg^(-1))下小麦产量、不同器官生物量、Cu质量比与积累量、Cu富集系数和迁移系数对褪黑素浓度变化的响应。结果表明:随着褪黑素浓度的升高,小麦苗期、拔节期、抽穗期和成熟期的生物量与产量呈先增后降趋势,而植株中各生育期Cu质量比整体呈先降后增趋势。适宜浓度的褪黑素能显著增加小麦产量和生物量,显著降低不同器官中Cu质量比、籽粒及叶的Cu富集系数和Cu由茎向籽粒/叶的迁移系数,缓解土壤Cu胁迫对小麦造成的生长抑制。整体上小麦各生育期的生物量和产量在MT2下达到最大,而地上部不同器官中Cu质量比、籽粒及叶的Cu富集系数和Cu由茎向籽粒/叶的迁移系数则为最小,均显著低于CK。MT2与CK相比,小麦各生育期穗、叶、茎、根的生物量和产量分别显著增加14.5%~154.5%和118.7%,而籽粒、叶、茎、根中的Cu质量比显著降低6.2%~204.1%,籽粒、叶中的Cu富集系数显著降低32.4%~58.1%,Cu由茎向籽粒和茎向叶的迁移系数则显著降低124.6%和106.5%。可见,适宜浓度的褪黑素处理能在一定程度上缓解土壤Cu胁迫对小麦生产的危害,其中500μmol·L^(-1)褪黑素的缓解效果最佳。

供氧浓度对受控生态生保系统典型生物质固废好氧堆肥的影响

目的探讨不同供氧浓度对生物质固废好氧堆肥化处理过程的影响机制,以掌握适用于未来地外星球基地受控生态生保系统(CELSS)固废资源化处理的供氧参数,提高氧气利用率。方法利用自研的固废生物反应器试验系统,以小麦秸秆和模拟粪便为处理对象,开展10%、15%和21%三种供氧浓度的好氧堆肥化处理实验,定期采样并分析处理过程中的气体组分(O_(2)、NH_(3)、CH_(4)和N_(2)O)及物料腐熟度(含水率、溶解性有机碳、NH_(4)^(+)-N和种子发芽指数)。结果15%O_(2)处理组耗氧量最大,NH_(3)和N_(2)O排放量最小,溶解性有机碳含量降解效果最好,NH_(4)^(+)-N含量较高;3个处理组中CH_(4)排放均处于较低水平。堆肥结束时,10%O_(2)和15%O_(2)处理组的产品含水率均大于74%,保水性最好,各处理组的种子发芽指数分别达到86.64%、123.81%和97.98%。结论与10%和21%供氧浓度相比,15%供氧浓度有效减少了NH_(3)和N_(2)O的排放,且拥有良好的保氮、保水和溶解有机碳降解效果,腐熟度更高。

应用波段深度分析和偏最小二乘回归的冬小麦生物量高光谱估算

当作物生物量较大时,现有植被指数由于受饱和问题限制,不能较好的估算作物生物量。针对此问题,尝试将波段深度分析与偏最小二乘回归(partial least square regression,PLSR)结合,提高对大田冬小麦生物量的估算精度,并将两者结合建立的模型与应用代表性植被指数建立的模型进行生物量估算精度比较。波段深度分析主要对冬小麦冠层光谱550～750nm范围进行,采用波段深度、波段深度比(band depth ratio,BDR)、归一化波段深度指数和归一化面积波段深度对波段深度信息进行表征。在建立的模型中,波段深度分析和PLSR结合的估算精度比应用植被指数模型的精度高,其中BDR与PLSR结合的估算精度最高(R2=0.792,RMSE=0.164kg.m-2)。研究结果表明波段深度分析与PLSR结合能较好的克服生物量较大时存在的饱和问题,提高冬小麦生物量的估算精度。

冬小麦生物量高光谱遥感监测模型研究

【目的】高光谱遥感能快速、实时、无损监测作物长势。研究不同氮磷水平下冬小麦不同生育时期地上部生物量高光谱遥感监测模型,可提高地上部生物量高光谱监测精度。【方法】在西北农林科技大学连续进行了5年田间定位试验,设置5个施氮水平(N,0,75,150,225和300 kg/hm^2)和4个磷施用水平(P2O5,0,60,120和180 kg/hm^2),选用不同抗旱类型冬小麦品种,测定了从拔节期至成熟期生物量与冠层光谱反射率,通过相关分析、回归分析等统计方法,建立并筛选基于不同植被指数的冬小麦不同生育时期生物量分段遥感监测模型。【结果】冬小麦生物量与光谱反射率在670 nm和930 nm附近具有较高相关性,在可见光和近红外波段处均有敏感波段;在拔节期、孕穗期、抽穗期、灌浆期、成熟期,生物量与归一化绿波段差值植被指数(GNDVI)、比值植被指数(RVI)、修正土壤调节植被指数(MSAVI)、红边三角植被指数(RTVI)和修正三角植被指数Ⅱ(MTVIⅡ)均达极显著相关性(P<0.01),相关系数(r)范围为0.923~0.979;在不同生育时期,分别基于GNDVI、RVI、MSAVI、RTVI和MTVIⅡ能建立较好的生物量分段监测模型,决定系数(R2)分别为0.987、0.982、0.981、0.985、0.976;估计标准误差SE分别为0.157、0.153、0.163、0.133、0.132;预测值与实测值间相对误差(RE)分别为8.47%、7.12%、7.56%、8.21%、8.65%;均方根误差(RMSE),分别为0.141 kg/m^2、0.113kg/m^2、0.137 kg/m^2、0.176 kg/m^2、0.187 kg/m^2。【结论】在拔节期、孕穗期、抽穗期、灌浆期、成熟期可以用GNDVI、RVI、MSAVI、RTVI和MTVIⅡ监测冬小麦生物量,具有较好的年度间重演性和品种间适用性。同时,分段监测模型较统一监测模型具有较好的监测效果及验证效果,能有效改善高光谱遥感监测模型精度。

基于Hyperion高光谱影像的冬小麦地上干生物量反演

在黄淮海粮食主产区选择河北省衡水市深州市为试验区,以冬小麦地上干生物量为研究对象,以作物冠层高光谱和EO-1 Hyperion高光谱卫星数据为主要数据源,在分析冠层高光谱构建的窄波段植被指数(N-VIs)与实测冬小麦地上干生物量间相关性基础上,提出了利用拟合精度R2极大值区域重心确定冬小麦干生物量敏感的光谱波段中心的方法,并运用该方法确定了冬小麦生物量敏感波段中心。在此基础上,以敏感波段中心筛选结果为指导,利用窄波段植被指数及相关波段开展Hyperion高光谱卫星遥感区域冬小麦干生物量遥感反演和精度验证。最终,按精度最高原则优选区域冬小麦地上生物量反演结果。其中,研究采用了冬小麦孕穗期Hyperion数据,涉及的植被指数包括窄波段归一化植被指数(N-NDVI)、窄波段差值植被指数(N-DVI)和窄波段比值植被指数(N-RVI)。结果表明,通过与实测冬小麦地上干生物量对比,利用冠层高光谱冬小麦地上干生物量反演敏感波段筛选结果及其相应波段构建的Hyperion窄波段植被指数进行孕穗期作物干生物量估算取得了较好结果,其精度由大到小为:NNDVI、N-RVI、N-DVI。其中,以波段B18(波长528.57 nm)、波段B82(波长962.91 nm)构建的Hyperion N-NDVI估算区域冬小麦地上干生物量精度最高,相对误差(RE)和归一化均方根误差(NRMSE)分别为12.65%和13.78%。

应用数字图像技术估测冬小麦冠层生物量垂直分布特征的研究

用数字图像技术研究了冬小麦冠层生物量的垂直分布。表明用一行小麦图像比多行小麦图像估测小麦生物量能更好地满足线性回归关系,估测效果更佳,以此为基础进一步研究了分层像素数估测小麦冠层分层现存生物量和有效生物量的方法。利用分层绿色像素数(LGPN)指标定性分析了不同栽培模式下冬小麦群体有效生物量的垂直分布和动态变化,并确定了基于图像特征的可用于定量分析的小麦群体垂直分布指数(I)。