Geostatistical interpolation and aggregation of crop growth model outputs

Many crop growth models require daily meteorological data. Consequently, model simulations can be obtained only at a limited number of locations, i.e. at weather stations with long-term records of daily data. To estimate the potential crop production at country level, we present in this study a geostatistical approach for spatial interpolation and aggregation of crop growth model outputs. As case study, we interpolated, simulated and aggregated crop growth model outputs of sorghum and millet in West-Africa. We used crop growth model outputs to calibrate a linear regression model using environmental covariates as predictors. The spatial regression residuals were investigated for spatial correlation. The linear regression model and the spatial correlation of residuals together were used to predict theoretical crop yield at all locations using kriging with external drift. A spatial standard deviation comes along with this prediction, indicating the uncertainty of the prediction. In combination with land use data and country borders, we summed the crop yield predictions to determine an area total. With spatial stochastic simulation, we estimated the uncertainty of that total production potential as well as the spatial cumulative distribution function. We compared our results with the prevailing agro-ecological Climate Zones approach used for spatial aggregation. Linear regression could explain up to 70% of the spatial variation of the yield. In three out of four cases the regression residuals showed spatial correlation. The potential crop production per country according to the Climate Zones approach was in all countries and cases except one within the 95% prediction interval as obtained after yield aggregation. We concluded that the geostatistical approach can estimate a country’s crop production, including a quantification of uncertainty. In addition, we stress the importance of the use of geostatistics to create tools for crop modelling scientists to explore relationships between yields and spatial environmental variables and to assist policy makers with tangible results on yield gaps at multiple levels of spatial aggregation.     

The application of geostatistics in erosion hazard mapping

Geostatistical interpolation or kriging of soil and vegetation variables has become an important alternative to other mapping techniques. Although a reconnaissance sampling is necessary and basic requirements of geostatistics have to be met, kriging has the advantage of giving estimates with a minimized error. In erosion hazard assessment this technique may therefore be applied instead of the conventional choropleth mapping, in order to improve the reliability of the input data for an erosion model. In a study, which was performed in the Ardèche district (Southern France) at a detailed scale (1:5000), the two methods are compared directly. It demonstrates a straightforward way to decide which method will give the best overall results at different sampling densities for erodibility controlling variables and the USLE K-factor. To this end a land unit map and several kriging maps of the investigated area (±2,5 km²) have been prepared. Quotients of kriging estimation variances and within-unit variances of the land unit map were calculated as a relative measure of error reduction. It was found that the kriging estimation variance is 66% (on average) of the within-unit variance for the USLE K-factor at a 150 meter sampling distance. This percentage can be further reduced to about 25% at a 50 meter sampling distance. It is concluded that kriging is an efficient option for mapping erodibility at this scale.     

回归克里格在土壤全氮空间预测上的应用

精确地了解表层土壤养分的空间分布,是生态环境保护,合理施肥及精准农业的基础。普通克里格法以区域化变量理论为基础,在土壤空间制图中得到了广泛的应用,但该方法过分依赖样点数据数量和质量,忽视了影响土壤养分的环境要素,因而该方法在空间预测上存在缺陷。研究以使用环境辅助变量的回归克里格法在土壤全氮空间插值效果及空间制图应用,并与普通克里格做比较,对二者的制图效果及插值精度进行评价。结果表明,回归克里法能充分地利用容易获取环境辅助变量,预测精度明显地高于普通克里格。在制图效果上,回归克里格法得到的预测图更能体现环境要素的作用痕迹,预测图在空间上过渡自然、平缓,很少有在过渡区域表现突变的现象,制图效果更符合全氮空间分布的实际。因此,回归克里格法适合环境因素影响明确,且与特定环境要素存在线性相关或特定趋势的土壤属性的预测和制图。     

从拮抗枯萎病的香蕉植株中分离内生细菌的研究初报

香蕉枯萎病已成为香蕉产业的毁灭性病害,近年在中国的香蕉主要区迅速蔓延,目前还未找到有效的解决措施。在海南枯萎病严重发病多年的香蕉园中,发现在严重感病致死的植株包围中,存在着能正常挂果并成熟的植株。由于它们在品种上的相同性,因此从品种的差异上难以解释该现象。分离了其中的内生微生物,发现其中的内生微生物主要以细菌为主,一部分细菌能分泌几丁质酶,对病原菌有一定的拮抗性,尤其在香蕉杆浸出汁培养基中对病原菌的生长有一定抑制作用。这为香蕉枯萎病的生物防治提供了一条较好的思路。     

抗FOC4内生放线菌NJQG-3A1的定殖与防效研究

为明确生防菌NJQG-3A1菌株在香蕉植株根、球茎、假茎、叶和根际土壤中的定殖情况和对香蕉枯萎病的生防作用,为香蕉枯萎病的生防治理提供理论依据,采用抗生素标记法测定菌株NJQG-3A1的定殖能力,以盆栽试验测定其对香蕉枯萎病的防控效果。定殖测定结果表明：以重铬酸钾（100μg/mL）-氨苄青霉素（100μg/mL）标记的NJQG-3A1菌株,可在香蕉根际土壤和植株的根、球茎、假茎中定殖,定殖量表现为：根际土壤＞根＞球茎＞假茎＞叶;在土壤中的定殖量可达1×10⁵ cfu/g;在香蕉植株内定殖量为1×10²~1×10³ cfu/g。盆栽试验结果表明：经NJQG-3A1菌株的发酵液处理后,香蕉植株的株高、茎围、鲜重比对照（接种病原菌,只施用清水）分别提高了99.22%,44.60%,218.67%,与对照差异显著（P＞0.05）;同时,菌株NJQG-3A1对香蕉枯萎病的防控效果显著,叶部与根茎部的病情指数分别为15、10;病情防效为81.82%,88.98%。NJQG-3A1菌株可以在香蕉植株和根际土壤中定殖,且该菌株的发酵液对香蕉枯萎病具有良好的防控效果,对香蕉植株的生长具有促进作用。     

Improvement of spatially and temporally continuous crop leaf area index by integration of CERES-Maize model and MODIS data

The spatially and temporally continuous leaf area index (LAI) mapping is very crucial for many agricultural applications, such as crop yield estimation and growth status monitoring. Data assimilation technology provides an innovational way to improve spatio-temporally continuous crop LAI estimation through integration of remotely sensed observations and crop growth models. In this study, a very fast simulated annealing (VFSA)-based variational assimilation scheme was proposed to integrate the crop growth model (CERES-Maize), MODIS reflectance product (MOD09A1) and a two-layer canopy reflectance model (ACRM) to estimate time-series crop LAI at regional scale. Simultaneously, a new sensitivity analysis method (called “histogram comparison”) was developed to identify sensitive parameters of CERES-Maize and ACRM models. The proposed scheme was applied for continuous crop LAI estimation during the maize growing season in the dominating spring maize planting area of Jilin province, China. Results showed that R² values between LAI estimations from the proposed assimilation scheme (referred to as assimilated LAI) and fine resolution LAI reference maps were 0.24 and 0.63, with RMSE values of 0.21 and 0.54 for Julian day 176, 2010, and Julian day 196, 2010, respectively. The assimilated results were closer to LAI reference maps than the MODIS LAI product and ACRM-based inversion results (referred to as ACRM LAI). Moreover, by introducing the prior information of LAI dynamics depicted by a crop growth model, the assimilated LAI showed better temporal consistency than the MODIS LAI product, LAI profiles simulated by CERES-Maize model (referred to as CERES-Maize LAI), and ACRM LAI. It was found that the accuracies of LAI estimations could be enhanced by assimilating satellite observations into a crop simulation model in the VFSA framework at a regional scale.     

复合生防菌剂防控香蕉枯萎病发生的效果探讨

香蕉枯萎病是由尖孢镰刀菌古巴专化型(Fusarium oxysporum f. sp. cubense,Foc)引起的毁灭性土传病害,在国内香蕉主产区持续暴发,使香蕉产业健康发展受到严重威胁和挑战,而利用生防菌进行防治是主要的防治对策和研究热点之一。平板对峙试验表明,自主筛选复配的复合生防菌剂(Trichoderma viride. XP1,Bacillus amyloliquefaciens. XP2)对Foc具有显著的抑菌效果。为进一步验证其作用效果,拟通过盆栽试验探讨复配复合生防菌剂防控香蕉枯萎病发生的效果,为其生物防治机制提供理论支撑。试验采用4个处理,分别为对照(CK)处理,接种灭活Foc4-GFP (100 mL)+灭活复合生防菌剂(500 mL);T1处理,接种Foc4-GFP (100 mL)+灭活复合生防菌剂(500 mL);T2处理,接种Foc4-GFP (100 mL)+复合生防菌剂(100 mL)+灭活复合生防菌剂(400 mL);T3处理,接种Foc4-GFP (100 mL)+复合生防菌剂(500 mL)。测定香蕉植株体内抗氧化酶、细胞壁降解酶的活性和致病毒素含量变化,调查香蕉植株的叶片数、株高、假茎直径、根系长度及发病指数。结果表明,接种复合生防菌剂的处理显著降低香蕉抗氧化性酶和细胞壁降解酶的酶活性(P<0.05)。可显著减少香蕉枯萎病致病毒素在香蕉体内的含量,接种复合生防菌剂的T2和T3处理香蕉假茎中镰刀菌酸(FA)、白僵菌素(BEA)和恩镰孢菌素(EB)的含量分别较T1处理降低93.31%、93.64%、94.71%和94.56%、95.76%、97.87%。接种复合生防菌剂在有效防控香蕉枯萎病发生的同时,可显著促进植株的生长,T2和T3处理香蕉枯萎病防治效果分别达81.7%和95.0%。接种复合生防菌剂能有效防控香蕉枯萎病,使香蕉体内CAT、POD、PAL、CMC、PME活性处于较低水平,极显著降低香蕉枯萎病致病毒素含量,防控效果达81.7%以上。     

香蕉枯萎病不同感病级别植株根际与非根际土壤微生物物种多样性研究

为了了解香蕉枯萎病患病蕉园土壤生态系统中的微生物群落特征以及香蕉植株枯萎病感病等级与土壤微生物群落结构的相关性。本研究于2010年采集了海南省的尖峰、冲坡和十月田3个典型香蕉枯萎病患病样地中健康植株和不同感病级别植株根际与非根际土壤样品共30份,采用微生物平板计数法分别研究了3个香蕉枯萎病典型患病样地中的土壤微生物物种多样性。结果表明：同一患病样地根际与非根际土壤中三大类群微生物的数量和种类均从感病级别高、感病级别低到健康植株持续增加,病原菌数量从感病级别高、感病级别低到健康植株持续降低。健康植株和不同感病级别植株根际土壤中的微生物数量均明显高于非根际,体现了根际效应。就细菌和放线菌来看,感病植株的根际效应最明显。     

茄科作物青枯病原菌的脂肪酸鉴定

【研究目的】采用脂肪酸鉴定技术对茄科作物青枯病原菌进行鉴定,以期为青枯病的预防与防治提供技术支持。【方法】采用选择性培养技术对茄子、番茄和辣椒病株进行青枯病原菌的分离和纯化,而后对青枯病原菌进行脂肪酸鉴定。【结果】经选择性培养分离得到的36株青枯病原菌中,有33株鉴定为典型的青枯雷尔氏菌（Ralstonia solanacearum）,占91.67%;茄子、番茄和辣椒上的青枯病原菌被鉴定为青枯雷尔氏菌的比例分别为100%、90%和89.47%。【结论】脂肪酸鉴定技术具有快速性、准确性,并可通过计算机的运用使分类达到数据化、自动化,可在茄科作物青枯病的检测中得到广泛的应用。     

区域墒情的空间分析方法与应用

为了探索区域墒情的分布规律,获得科学的采样方案和分析方法,以北京通州区3022个点的土壤含水量数据为研究对象,综合利用距离反比法、普通克里金法、协克里金法、随机模拟法4种空间分析方法对区域内6、10、15、20 cm土层含水量进行了统计分析。研究表明,20 cm土层含水量较其他土层稳定,更适合作为土壤墒情的预测指标。随机模拟法平滑效应小,产生的区域墒情分布图与其他种方法生成的分布图差异较大,仅适用于存在较大变异的区域墒情分析。普通克里金、距离反比法、协克里金法产生的分布图基本一致,可用于一般区域墒情分析,其中,考虑6 cm土层含水量的协克里金法较普通克里金法减少了40%~60%的方差,是区域墒情分析的最优方法。在此基础上,提出了一种充分利用表层土壤含水量值来提高墒情预测精度的采样方法。     

香蕉枯萎病发病机制及其防治技术研究

从香蕉枯萎病的病原菌及其发病机制和香蕉抗病机制等多方面阐述了国内外的研究进展,研究表明枯萎病菌的4号小种对中国香蕉生产影响最大,果胶酶和毒素是引起香蕉致病的主要毒力因子,此外,还有一些小分子的成分和作用有待进一步明确。阐述了香蕉枯萎病的防治现状。     

农约“农抗120”田间应用技术研究

研究了农药“农抗120”对枯萎病的作用方式,认为以浸种和灌根方法使药剂进入植物体,可显著降低枯萎病的发病率,并据此研究了防治瓜、菜枯萎病的关键技术.通过田间试验,提出了对果树腐烂病、作物叶部病害等不同类型病害的防治策略和技术.     

数量性状基因的完备区间作图方法

结合分子标记和表型数据的QTL作图已成为数量性状遗传分析的常规方法。复合区间作图是近10多年来广泛应用的一种QTL定位方法,但它在算法上有一些缺陷,致使QTL效应可能会被侧连标记区间之外的标记变量吸收,同时不同的背景标记选择方法对作图结果的影响较大,并且难以推广到上位型互作QTL的定位。针对这些问题,笔者提出完备区间作图方法。本文介绍了该方法的遗传和统计原理,并通过一个大麦加倍单倍体群体说明其在定位加性QTL和加性×加性互作QTL中的应用。完备区间作图包含两个步骤：首先利用所有标记的信息,通过逐步回归选择重要的标记变量并估计其效应;然后利用逐步回归得到的线性模型校正表型数据,通过一维扫描定位加(显)性效应QTL,通过二维扫描定位上位型互作QTL。这种作图策略简化了复合区间作图中控制背景遗传变异的过程,提高了对QTL的检测功效。     

枯草芽孢杆菌TR21对香蕉抗病相关酶活的诱导作用

为筛选能显著诱导香蕉抗病相关酶活变化的枯草芽孢杆菌TR21（Bacillus subtilis）发酵液组分,并探讨其诱导香蕉抗病性机理,选择多酚氧化酶（PPO）、过氧化物酶（POD）和苯丙氨酸解氨酶（PAL）作为植物抗病性反应指标,采用灌根接种法,研究1株在大田对香蕉枯萎病具有良好防效的枯草芽孢杆菌TR21发酵液不同组分对香蕉根系内3种酶活性的影响。结果表明,接种TR21发酵液、菌体、上清和NB培养基后,香蕉根系内PPO、POD和PAL活性均比无菌水对照高,且都出现2次高峰,PPO、POD活性峰在接种后第3天和第7天出现,PAL活性峰则在接种后1天和5天时出现。比较不同组分接种处理诱导产生的酶活性强弱发现,接种TR21发酵液、菌体的3种酶活性均明显高于接种上清和NB的处理。可以判断TR21发酵液中主要有效诱导组分为菌体。灌根法接种TR21菌体后测定香蕉叶片中3种抗病酶的活性表明,菌体处理后叶片中PPO、POD和PAL活性均显著高于接种无菌水的对照,推测诱导系统抗性可能是TR21菌株防治香蕉枯萎病的机制之一。     

Inheritance of resistance to Fusarium oxysporum f. sp. cubense race 1 in bananas

Fusarium wilt of bananas (also known as Panama disease), caused by the soil-borne fungus Fusarium oxysporum f. sp cubense (Foc), is a serious problem to banana production worldwide. Genetic resistance offers the most promising means to the control of Fusarium wilt of bananas. In this study, the inheritance of resistance in Musa to Foc race 1 was investigated in three F₂ populations derived from a cross between ‘Sukali Ndizi’ and ‘TMB2X8075-7’. A total of 163 F₂ progenies were evaluated for their response to Fusarium wilt in a screen house experiment. One hundred and fifteen progenies were susceptible and 48 were resistant. Mendelian segregation analysis for susceptible versus resistant progenies fits the segregation ratio of 3:1 (χ² = 1.72, P = 0.81), suggesting that resistance to Fusarium wilt in Musa is conditioned by a single recessive gene. We propose panama disease 1 to be the name of the recessive gene conditioning resistance to Fusarium wilt in the diploid banana ‘TMB2X8075-7’.     

豆粕发酵液对香蕉幼苗枯萎病防效的影响

为了研究豆粕发酵液对香蕉枯萎病的防治效果,笔者使用从发酵菌液中分离得到的对香蕉枯萎病病原菌--尖孢镰刀菌古巴专化型4号生理小种（Fusarium oxysporum f.sp.cubense race 4,Foc4）有拮抗效果与促生效果（即非抑制效果但对香蕉植株有促生作用）的菌液及混合菌液,分别对香蕉幼苗进行伤根淋菌、未伤根淋菌处理。结果表明：不同试验处理对香蕉枯萎病均有不同程度地防效。其中,使用混合发酵液对未伤根的香蕉幼苗进行淋菌处理,可显著提高超氧化物歧化酶（SOD）、过氧化物酶（POD）的活性,增加游离脯氨酸的含量,降低MDA值,对香蕉枯萎病防效达到94.3%。     

尖孢镰刀菌古巴专化型SIX7基因分析

SIX蛋白编码基因最早由尖孢镰刀菌番茄专化型入侵的番茄木质部蛋白质组中发现,且成功用于区分尖孢镰刀菌番茄专化型的3个生理小种。一些SIX编码基因亦在引起香蕉枯萎病的Fusarium.oxysporum f. sp. cubense（简称Foc）中有报道,为区分Foc不同生理小种或亚型,比较分析了Foc中的SIX7基因序列及其特异性。以现有的SIX7基因序列设计合成引物,通过PCR扩增并测序,比较分析国内不同地理区域及来源于澳大利亚与南非的Foc1、Foc2、Foc3、Foc4共56株菌株中的SIX7基因,并以8个以上其他专化型或其他种或属病原菌共39株菌株分析了SIX7基因序列的特异性。研究发现所设计合成的SIX7基因引物序列仅能从供试的亚热带4号生理小种(ST4)中扩增出663 bp的目的条带。亚热带4号生理小种(ST4)中仅有的SIX7基因序列结合Foc4特异性引物Foc-1/Foc-2可快速区分Foc4亚型,提供了快速区分香蕉枯萎病病样内的Foc4亚型的分子鉴定手段,可指导蕉农及时采取有效防控香蕉枯萎病的措施。     

香蕉内生拮抗细菌KKWB-10的分离鉴定及其内生性证明

从香蕉体内分离拮抗香蕉枯萎病菌的内生细菌,旨在应用于香蕉枯萎病的生物防治。从健康香蕉植株的球茎分离到多株细菌,对其进行了拮抗香蕉枯萎病菌4号小种的实验,选择其中1株拮抗性较强的菌株KKWB-10进行了形态特征、生理生化测定、16S rDNA序列分析,并通过浸根法将标记了绿色荧光蛋白GFP的该菌（K-pUCK7-1′GT菌）回接无菌的香蕉组培苗,培养10天后,制备香蕉苗的根和茎的手工切片于激光共聚焦显微镜下观察。抑菌实验结果表明,该菌株对香蕉枯萎病菌4号生理小种有较强的抑制作用。通过形态学观察、生理生化指标测定、16S rDNA序列同源性分析,将该菌株初步鉴定为阴沟肠杆菌(Enterobacter cloacae)。激光共聚焦显微镜观察发现经K-pUCK7-1′GT菌液处理的香蕉组培苗的根和茎的切片中均发现绿色荧光,而未处理的对照组的香蕉苗却没有发现绿色的荧光,表明该菌株能定殖于香蕉的根和茎内。该菌株可直接作为生防菌剂,也可用作外源抗病基因在香蕉植株体内表达的载体,在香蕉枯萎病菌的生物防治中具有一定的潜在价值。     

SIMBA-N: Modeling nitrogen dynamics in banana populations in wet tropical climate. Application to fertilization management in the Caribbean

In banana plantations of the Caribbean, nitrogen (N) fertilization widely exceeds nutrient outputs after harvest. Under wet tropical climate, leaching results in considerable waste of N. Fertilization management aims at maintaining soil mineral N at the optimal level for banana nutrition throughout the year but it does not take into account variations in crop N demand or N supply through mineralization of crop residues. The dynamics of crop N demand and crop residue supply depend on the structure of banana populations, which become asynchronous with time. We designed the SIMBA-N model to simulate N dynamics in successive crop cycles of banana. The model calculates the N balance weekly, including N uptake by banana, N leaching, and N supply by organic matter mineralization. We validated the model using data from a field experiment comparing five levels of fertilization. Results showed SIMBA-N provides reliable indicators to support banana fertilization management taking into account N flows in the soil and change in N demand related to banana population structure.     

河南省芝麻主要病害综合治理研究

明确了河南省芝麻主要病害——苗病、病毒病、茎点枯病和叶斑病的发生危害及田间流行动态;试验筛选出抗病品种,复方多菌灵防治苗病、茎点枯病、叶斑病和40％氧化乐果治蚜防病毒病。据此提出以抗病品种为基础,药剂防治为保证的防治策略,制定出多种病害综合防治技术。经多点试验及示范推广,防病增产效果显著。