基于多核支持向量机的小麦条锈病遥感监测研究

为提高小麦条锈病的遥感探测精度,依据日光诱导叶绿素荧光和冠层反射光谱数据在小麦条锈病遥感探测中的优势及其与病情严重度之间的映射关系,在运用独立分量分析法对光谱数据降维的基础上,利用核学习算法分别确定冠层光谱特征和日光诱导叶绿素荧光特征反映小麦条锈病病情严重度的最优核,同时针对冠层光谱与叶绿素荧光特征组,建立基于不同特征最优核映射的多核学习支持向量机模型,并与基于特征直接拼接的模型结果进行对比。结果表明,对于冠层光谱而言,采用高斯核构建的支持向量机模型可较好估测小麦条锈病病情指数,而日光诱导叶绿素荧光指数则是采用多项式核的效果更优;采用直接拼接法融合叶绿素荧光指数和冠层光谱特征能够在一定程度上改善小麦条锈病病情指数估测精度,决定系数(r~2)最高为0.847,而单独利用冠层光谱信息或者叶绿素荧光信息时,r~2最高仅为0.802;对日光诱导叶绿素荧光和反射光谱特征分别利用其最优核进行映射构建的多核学习支持向量机模型精度最高,r~2为0.915,RMSE为0.090,优于基于特征直接拼接构建的支持向量机模型精度。     

基于光谱指数的冬小麦冠层叶绿素含量估算模型研究

为探索对冬小麦冠层叶绿素含量反应敏感的高光谱波段组合,同时比较不同光谱指数对小麦冠层叶绿素含量的估测效果,通过分析350~2 500nm波段范围内原始光谱反射率及其一阶导数光谱的任意两两波段交叉组合而成的主要高光谱指数与冬小麦冠层叶片叶绿素含量的定量关系,建立冬小麦冠层叶绿素含量估算模型。结果表明,选用归一化光谱指数(NDSI)、比值光谱指数(RSI)、差值光谱指数(DSI)和土壤调节光谱指数(SASI)建立的冬小麦冠层叶绿素含量监测模型决定系数均大于0.71,标准误差均小于1.842。利用独立试验资料进行检验,表现最好的是RSI(FD_(689),FD_(609))和SASI(R_(491),R_(666))L=0.01,预测精度高达98.2%,模型精确度和可靠性较高。     

基于主成分分析和随机森林回归的冬小麦冠层叶绿素含量估算

为提高冬小麦冠层光谱对叶绿素含量的估算精度,以陕西省乾县冬小麦为研究对象,利用SVC-1024i光谱仪和SPAD-502型叶绿素仪实测了冬小麦冠层反射率和叶绿素含量,分析了一阶导数光谱、10种特征参数和9种植被指数与叶绿素含量的相关性,并利用主成分分析(PCA)对叶绿素敏感的可见光波段(390～780 nm)一阶导数光谱进行降维,将特征值大于1的主分量结合特征参数和植被指数形成不同的输入变量,用偏最小二乘回归和随机森林回归构建冬小麦冠层叶绿素估算模型,并利用独立样本对模型进行验证。结果表明,小麦冠层叶绿素含量与一阶导数光谱在751 nm处的相关性最高(r=0.71),特征参数中红边蓝边归一化(SDr-SDb)/(SDr+SDb)与叶绿素含量的相关性最高(r=0.66),植被指数(VI)中修正归一化差异指数(mND705)相关性最高(r=0.74)。在输入变量相同的情况下,基于随机森林(RF)回归的预测模型均优于偏最小二乘回归(PLSR)模型,其中PCA-VI-RF模型的各精度指标均达到最优(r²=0.94,RMSE=1.05,RPD=3.70),是冬小麦冠层叶绿素...     

联合主成分分析与最小二乘支持向量机估测冬小麦叶面积指数

利用单一植被指数估测叶面积指数存在高光谱遥感丰富的波段信息易丢失和外界因素干扰大的缺点,但若将波段信息全部引入模型又会增加建模难度。为解决利用多波段信息估测叶面积指数的问题,利用主成分分析法(PCA)对光谱数据进行降维,之后将提取的主成分与最小二乘支持向量机(LS-SVM)模型相结合,构建冬小麦叶面积指数的高光谱估测模型,并与以4类植被指数作为LS-SVM输入参数建立的模型进行比较。结果表明,以主成分作为LS-SVM模型的输入参数建立的模型精度最高,模型检验集R2为0.71,检验集RMSE为0.56,估测结果较使用植被指数作为输入参数建立的模型精度高,稳定性好。该方法可为利用多波段信息进行大范围冬小麦叶面积指数的无损测定提供参考。     

基于Dualex植物多酚-叶绿素仪的冬小麦叶绿素含量高光谱估算

为探讨基于Dualex植物多酚-叶绿素仪和高光谱遥感技术反演小麦叶绿素含量的可行性,利用Dualex植物多酚-叶绿素仪,测定不同生育时期冬小麦叶片叶绿素含量(Chl),同时进行叶片光谱测定,以对Chl敏感的1个一阶导数波段、3个三边参数和3个植被指数作为自变量,利用偏最小二乘法(PLS)和支持向量回归(SVR)构建估测模型,并利用验证样本对各生育时期估测模型进行精度检验,同时与传统的单因素模型进行了比较。结果表明,冬小麦反射光谱曲线在不同生育时期有所不同,且随着叶绿素含量的增加,可见光波段的光谱反射率不断降低;在以一阶导数光谱敏感波段、三边参数以及植被指数构建的冬小麦Chl单因素估算模型中,基于各生育时期显著相关的植被指数构建的模型精度最优;以7个参数作为自变量,利用偏最小二乘法(PLS)和支持向量回归(SVR)构建的模型在各生育时期均表现出较好的拟合性及预测精度,尤其利用SVR建立的模型建模决定系数在0.8以上,预测决定系数在0.7以上,是进行冬小麦叶片Chl估测的最优模型。     

基于高光谱的冬小麦不同生育时期地上部生物量监测

为实现冬小麦不同生育时期地上部生物量的高光谱监测,2017-2019年分别在河南省鹤壁市、原阳县和温县布置冬小麦氮肥梯度田闻试验,分别于分蘖期、拔节期、抽穗期和灌浆期测定冬小麦地上部生物量及其冠层原位高光谱反射率(400～950 nm),并采用Pearson相关分析明确两者间定量回归关系,再分别利用支持向量机(supp...     

小波特征与传统光谱特征估测冬小麦条锈病病情严重度的对比研究

为探讨通过小波特征监测小麦条锈病发病程度的可行性,利用连续小波变换提取的小麦冠层光谱350~1 300 nm范围内的9个小波特征和传统光谱特征（植被指数、一阶微分变换特征和连续统特征）,借助偏最小二乘回归（PLSR）建立反演模型,分别将传统光谱特征（SFs）、小波特征（WFs）及传统光谱特征与小波特征结合(SFs & WFs）作为模型的输入,对小麦条锈病病情进行反演。结果表明：（1）小波特征与条锈病严重度的相关性比传统光谱特征强;（2）基于小波特征的模型估测精度（R为0.837）优于基于传统光谱特征的模型估测精度（R为0.824）;（3）传统光谱特征与小波特征结合的模型精度最高,R为0.876,RMSE仅为0.096,因而传统光谱特征与小波特征相结合能够更好地对小麦条锈病病情严重度进行估测。     

基于支持向量机模型的冬小麦全蚀病为害等级遥感监测

为了解利用高光谱遥感技术对小麦全蚀病进行有效监测的可行性,对感染不同发病等级全蚀病的冬小麦冠层光谱反射率数据进行采集分析,选取监测敏感波段,在Matlab和Libsvm工具箱支持下,利用支持向量机分类方法构建小麦全蚀病病害等级预测模型。结果表明,在不同程度小麦全蚀病的为害下,小麦冠层光谱反射率存在明显变化。通过对数据分析,选择700~900nm波段作为敏感波段进行训练建立模型的结果最好;经检验,基于此波段构建的预测模型预测值与实际值相关系数可达0.943,均方根达0.63,因此生产上可利用波段光谱特征对小麦全蚀病进行监测。     

基于连续投影算法和光谱变换的冬小麦生物量高光谱遥感估算

为探索基于全波段冠层高光谱以及变换光谱的冬小麦地上部生物量的遥感估算方法,以2016、2017年冬小麦田间试验为基础,通过对冠层光谱和地上部生物量的相关性分析,筛选拔节期、抽穗期的冬小麦冠层光谱、一阶导数光谱、对数变换光谱和连续统去除光谱对地上部生物量的敏感波段,并结合偏最小二乘法(PLS)分别建立拔节期和抽穗期基于SPA算法的冬小麦地上部生物量估测模型,再与基于任意两波段组合的最佳归一化光谱指数、比值光谱指数、差值光谱指数和已报道光谱指数的冬小麦地上部生物量估测模型进行比较。结果表明：(1)SPA算法较好地利用了全波段冠层光谱信息,并显著降低了光谱维度,不同变换光谱的地上部生物量敏感波段个数在4~14之间;(2)拔节期和抽穗期冠层光谱与地上部生物量的相关性高于开花期和灌浆期,各生育时期一阶导数光谱与地上部生物量之间的相关性优于连续统去除光谱、对数变换光谱和光谱指数;(3) 利用抽穗期一阶导数光谱敏感波段建立的预测模型和验证模型达到了较高的精度,其预测模型的决定系数和均方根误差分别为0.78和0.87 t·hm^-2,验证模型的决定系数和均方根误差分别为 0.84和0.69 t·hm^-2,预测相对偏差为2.74。这说明,抽穗期是估算地上部生物量的最佳生育时期,且基于冠层一阶导数变换光谱,结合连续投影算法和偏最小二乘回归方法所构建抽穗期地上部生物量估算模型具有最优的精度和预测能力,可用于地上部生物量的定量估算。     

多光谱与热红外数据融合在冬小麦产量估测中的应用

为了解多光谱与热红外数据融合对冬小麦产量估测精度的影响,以30个黄淮麦区冬小麦品种为材料,利用三种灌溉处理（处理1、处理2和处理3灌水量分别为240、190和145 mm）下冬小麦拔节期、挑旗期、抽穗期与灌浆期的无人机多光谱和热红外动态数据,构造了多个光谱指数,以支持向量机构建冬小麦产量估测模型,并验证其精度。结果表明,植被指数与籽粒产量的相关性受溉水量影响,处理1下植被指数与籽粒产量均呈正相关,处理2下植被指数除土壤调整植被指数（SAVI）和转化叶绿素吸收反射指数（TCARI）外均与籽粒产量呈正相关,处理3下植被指数与籽粒产量均呈负相关。通过多光谱和热红外数据融合构建的冬小麦产量估测模型的预测精度比仅使用多光谱数据构建的模型提高8%。不同灌溉条件下,通过多光谱与热红外数据融合构建的模型的预测精度存在差异,在处理1、处理2和处理3下拔节期、挑旗期、抽穗期和灌浆期验证决定系数（R）最高值分别为0.63、0.68和0.56,均方根误差（RMSE）最低值分别为0.60、0.24和0.41 t·hm^-2,且在三种灌溉条件下灌浆期预测效果均最佳。因此,利用无人机光谱对小麦品种产量估测时应将多光谱与热红外数据融合,用支持向量机（SVM）算法构建产量估测模型,且模型在灌浆期具有较高预测  精度。     

钾素水平对油菜酶活性的影响

利用盆栽试验研究不同钾素施用水平对油菜薹期酶活性的影响。结果表明 ,钾素缺乏和过量均可导致油菜叶片POD含量上升 ,CAT和SOD含量下降。不同施钾水平条件下 ,油菜下部叶的酶活性差异比上部叶更明显     

Haloarchaea as Cell Factories to Produce Bioplastics

Plastic pollution is a worldwide concern causing the death of animals (mainly aquatic fauna) and environmental deterioration. Plastic recycling is, in most cases, difficult or even impossible. For this reason, new research lines are emerging to identify highly biodegradable bioplastics or plastic formulations that are more environmentally friendly than current ones. In this context, microbes, capable of synthesizing bioplastics, were revealed to be good models to design strategies in which microorganisms can be used as cell factories. Recently, special interest has been paid to haloarchaea due to the capability of some species to produce significant concentrations of polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), and polyhydroxyvalerate (PHV) when growing under a specific nutritional status. The growth of those microorganisms at the pilot or industrial scale offers several advantages compared to that of other microbes that are bioplastic producers. This review summarizes the state of the art of bioplastic production and the most recent findings regarding the production of bioplastics by halophilic microorganisms with special emphasis on haloarchaea. Some protocols to produce/analyze bioplastics are highlighted here to shed light on the potential use of haloarchaea at the industrial scale to produce valuable products, thus minimizing environmental pollution by plastics made from petroleum.     

不同杀菌方式对龙眼原汁品质的影响

为了探讨不同杀菌方式在达到商业杀菌要求的基础上对龙眼原汁营养成分及理化性质的影响,以广西南宁地区所产的“石硖”龙眼为原料,对比分析了巴氏杀菌(PS)、微波杀菌(MS)、超高温瞬时杀菌(UHT)和高压脉冲电场杀菌(PEF)4种杀菌方式对龙眼原汁的菌落总数、色差、pH值、可溶性固形物、总酚、糖组分及有机酸等指标的影响。结果表明：4种杀菌方式均能达到商业无菌要求,对龙眼原汁的pH值和葡萄糖含量无显著性影响(p>0.05);与对照组(CK)相比,PEF杀菌对龙眼原汁中L*值、b*值、可溶性固形物(TSS)、果糖、总糖、酒石酸、富马酸含量影响不显著(p>0.05);与PS、MS和UHT杀菌相比,PEF杀菌对龙眼原汁中的总酚、抗坏血酸、总酸的影响幅度较小。因此,PEF杀菌技术不仅具有较好的杀菌效果,而且能更好地保持龙眼汁原有的色泽和营养品质。     

叶面喷施微肥对冬小麦产量和品质的影响

为给小麦高产优质栽培中微肥施用提供参考,以冬小麦品种石新828为材料,研究了叶面喷施锌、铁、硒3种微肥对小麦产量、籽粒锌、铁、硒和蛋白质含量的影响。结果表明,3种微肥中只有喷硒增产作用显著(P<0.05),但喷锌、铁、硒分别显著增加了千粒重、穗数和穗粒数。3种微肥均能明显提高籽粒中相应的微量元素含量,但对籽粒蛋白质含量影响均不显著。     

Quantitation Overcoming Matrix Effects of Lipophilic Toxins in Mytilus galloprovincialis by Liquid Chromatography-Full Scan High Resolution Mass Spectrometry Analysis (LC-HR-MS)

The analysis of marine lipophilic toxins in shellfish products still represents a challenging task due to the complexity and diversity of the sample matrix. Liquid chromatography coupled with mass spectrometry (LC-MS) is the technique of choice for accurate quantitative measurements in complex samples. By combining unambiguous identification with the high selectivity of tandem MS, it provides the required high sensitivity and specificity. However, LC-MS is prone to matrix effects (ME) that need to be evaluated during the development and validation of methods. Furthermore, the large sample-to-sample variability, even between samples of the same species and geographic origin, needs a procedure to evaluate and control ME continuously. Here, we analyzed the toxins okadaic acid (OA), dinophysistoxins (DTX-1 and DTX-2), pectenotoxin (PTX-2), yessotoxin (YTX) and azaspiracid-1 (AZA-1). Samples were mussels (Mytilus galloprovincialis), both fresh and processed, and a toxin-free mussel reference material. We developed an accurate mass-extracted ion chromatogram (AM-XIC) based quantitation method using an Orbitrap instrument, evaluated the ME for different types and extracts of mussel samples, characterized the main compounds co-eluting with the targeted molecules and quantified toxins in samples by following a standard addition method (SAM). An AM-XIC based quantitation of lipophilic toxins in mussel samples using high resolution and accuracy full scan profiles (LC-HR-MS) is a good alternative to multi reaction monitoring (MRM) for instruments with HR capabilities. ME depend on the starting sample matrix and the sample preparation. ME are particularly strong for OA and related toxins, showing values below 50% for fresh mussel samples. Results for other toxins (AZA-1, YTX and PTX-2) are between 75% and 110%. ME in unknown matrices can be evaluated by comparing their full scan LC-HR-MS profiles with those of known samples with known ME. ME can be corrected by following SAM with AM-XIC quantitation if necessary.     

52个甘蔗品种在广西受病毒侵染情况

为明确国家糖料体系甘蔗集成示范及区试品种在广西被病毒侵染情况,2017年从广西北海、南宁、崇左、百色、来宾、柳城、桂林等地集成示范及区试的52个甘蔗品种上采集带有甘蔗花叶病、甘蔗黄叶病和甘蔗杆状病毒病显著病症或不显病症叶片样品,采用特异引物通过RT-PCR和PCR方法进行5种病毒检测（甘蔗黄叶病毒、甘蔗线条花叶病毒、高粱花叶病毒、甘蔗花叶病毒和甘蔗杆状病毒）。结果表明,SCYLV的平均检出率为25.00%;SCSMV的平均检出率为7.97%;SrMV的平均检出率为7.69%;SCMV的平均检出率最低,为7.42%;SCBV的平均检出率最高,为68.41%,远远高于其他病毒。7个地方的甘蔗受病毒混合侵染现象普遍存在,北海的病毒混合侵染率甚至高于单一病毒侵染率。52个甘蔗品种在广西受5种病毒的总侵染率为79.67%,对甘蔗的生产安全存在着严重的潜在威胁,建议推广种植甘蔗脱毒种苗来缓解甘蔗病毒病害的危害。     

红麻粉蚧虫形态特征的观察

本文描述了危害我国华南留种红麻两种粉蚧:木槿曼粉蚧Maconellicoccushirsutus(Green)、拟葡萄粉蚧PseudococcusViburini(Signoret)的主要形态特征及其差异比较,这对红麻害虫虫种的识别及指导防治具有重要意义。     

Association mapping in rice: basic concepts and perspectives for molecular breeding

In the last decade, association mapping (AM) has become a well-established method to detect genes and quantitative trait loci (QTLs) associated with agronomically important traits. The identification of a large number of single nucleotide polymorphisms (SNPs) from genome sequencing and concurrent development of high-throughput genotyping platforms has led to AM being widely used for a range of crops. These technologies have been used in rice (Oryza sativa) to explore the abundant diversity and there is enormous potential to identify novel QTLs for traits of interest. Due to the availability of cost-effective high-throughput SNP genotyping methods and rapid developments in rice genomics, it is inevitable that these AM approaches will become more popular in the future, especially in the context of genome-wide association studies (GWASs). In this paper, we review the fundamental concepts, critical considerations and limitations of AM focusing on rice, and reiterate the importance of accurate phenotypic data. We also include a section about connecting GWAS to molecular breeding, covering practical consideration for breeders, which is required to use GWAS results in actual rice molecular breeding programs and which has not received adequate attention in the scientific literature.     

利用Affymetrix芯片分析DON诱导抗赤霉病小麦品种望水白的基因表达谱

中国小麦地方品种望水白不但高抗赤霉病,而且其籽粒中DON(脱氧雪腐镰刀菌烯醇,被认为是赤霉病的致病因子)含量也低.为了研究望水白低DON含量的分子机制,利用Affymetrix小麦基因芯片对望水白受DON诱导调控的基因进行高通量的检测,以DON诱导后12 h和24 h混合样品作为处理组,水处理做为对照.总共检测到差异表达的基因1 114个,其中上调表达的基因有949个,下调基因165个.在上调表达基因中,推断有功能的基因涉及转录因子、信号蛋白、着丝粒蛋白以及与病程相关的基因,如:腺苷三磷酸结合盒转运蛋白,谷胱甘酞转移酶、细胞色素P450酶、苯丙氨酸解氨酶、葡萄糖基转移酶以及抗病蛋白等.对上调表达中的部分基因进行RT-PCR分析,证实它们都受DON诱导上调表达,与芯片检测结果吻合.     

Collaborative breeding with farmers can be effective

Plant breeding efficiency is increased by better taking into account the needs of the clients. This can sometimes be helped by involving farmers in selection in the segregating generations. We describe a rice-breeding programme in Nepal where the use of simple breeding methods optimised the benefits from such collaboration. Farmers grew in their fields large populations that were bulks derived from the F₂ generations of single crosses. They selected within them starting in a generation where selfing was sufficiently advanced for the between-plant heritability to be high. Poorer bulks were soon rejected by farmers. A high proportion selected within the bulks and a significant proportion did so over several generations. An increasing number of farmers grew the best of the selected bulks because they spread from farmer to farmer without the need of intervention from scientists. Varieties selected from these bulks were preferred by farmers in on-farm trials and had a superior combination of yield and maturity compared with the later breeders’ selection from the same bulk. Levels of participation were higher with the better performing bulks and even when training was not provided, provided the germplasm performed acceptably well sufficient farmers selected in the bulks to make collaborative breeding cost effective. Collaborative breeding can be successful but demands different types of resources than those for on-station breeding so its cost effectiveness will vary with circumstances. It can be used to increase the probability of selecting segregants that perform well across environments by using methods that pool bulks selected by different farmers and it is also extremely useful for decentralising breeding programmes.