棉花叶面积指数和地上干物质积累量的高光谱估算模型研究

 用ASD FieldSpec光谱仪实测棉花冠层不同生育时期的高光谱数据,同期获取棉花叶面积指数(LAI)和地上干物质积累量(Above-ground Dry Matter Accumulation,ADMA)。分析棉花冠层反射光谱与棉花LAI、地上部干物质积累量（ADMA）的相关关系,分析结果表明,反射光谱数据与棉花LAI、ADMA的相关系数的最高值分别发生在783 nm（r=0.6394^**）和766 nm处(r=0.6287^**);对反射光谱数据进行统计分析,建立了基于比值植被指数(RVI)和归一化植被指数(NDVI)的5种函数形式的棉花LAI、ADMA估测模型。经检验,基于RVI的估测模型具有较高的精度;对一阶微分光谱数据与棉花LAI和ADMA的逐步回归相关分析表明,敏感波段分别发生在736 nm（r=0.6769^**）和742 nm处(r=0.6847^**)。由736 nm、742 nm波段处的微分数值建立的LAI和ADMA线性回归估测模型,R值均达到了1%极显著的检验水平,说明一阶微分光谱敏感波段的数值,对棉花LAI和ADMA具有一定的估算能力。     

不同水分条件下棉花光谱数据对冠层叶片温度的响应特征

利用Fluke热像仪和ASD地物非成像高光谱仪,分别记录棉花新陆早33号、13号2个品种、4个水分处理、5个关键生育时期的冠层红外热图像和反射光谱数据;在红外热图像上提取棉花冠层受光叶片的温度,同时处理高光谱数据获得归一化植被指数(NDVI)、比值植被指数(RVI)、红光620 nm和近红外850 nm波段的反射率(ρ620,ρ850)。分析表明,棉花2个品种4个水分处理的冠层叶片温度(TL)在盛花期、盛花结铃期较高,在盛铃期达到最大值,在开花期和吐絮初期较低;棉花受到水分胁迫,冠层近红外波段光谱的反射率降低,红光波段的反射率升高,NDVI和RVI变小,TL升高;在充分灌溉条件下棉花近红外、红光波段的光谱反射率、NDVI和RVI及TL则与水分胁迫处理的表现相反。和620 nm和850 nm波段反射率与TL的线性相关比较,棉花NDVI和RVI与TL的线性相关性更强。研究表明,将红外热图像和高光谱遥感技术相结合,具有实时、非破坏性地监测棉花水分状况的潜力。     

基于冠层反射光谱的玉米LAI和地上干物重估测研究

以cropscan多光谱辐射仪测定了玉米品种郑单958和浚单20的冠层光谱反射率,并对其相应的叶面积指数(LAI)和地上干物质量进行了同步测定。将由近红外波段和可见光红波段组成的不同的归一化植被指数(NDVI)和比值植被指数(RVI)分别与叶面积指数、地上干物质量进行回归分析,结果表明,NDVI与叶面积指数的相关性优于RVI与叶面积指数的相关性,且以NDVI(R950,R650)和叶面积指数的幂函数回归结果最优;RVI与地上干物质量的二项式回归效果显著,估算模型为:Y=-0.722 4(R800/R650)2 1.631 6(R800/R650) 271.49,R2=0.793 5。     

棉花叶绿素密度和叶片氮积累量的高光谱监测研究

利用非成像高光谱仪,获取棉花不同品种、不同密度冠层关键生育时期的反射光谱数据,应用光谱多元统计分析技术,研究表明,棉花冠层叶绿素密度（CH.D）和叶片氮积累量（LNA）分别在反射光谱762 nm和763 nm处的相关系数达最大值（R_CH.D= 0.8845**和R_LNA= 0.7870**,n = 47）;而一阶微分光谱数据对CH.D、LNA最敏感的波段均发生在750 nm处(R_CH.D= 0.9098**和R_LNA = 0.9164**,n = 47);采用47个建模样本的一阶微分光谱750 nm处的数值与棉花冠层CH.D建立线性相关模型方程,估算47个检验样本的棉花冠层CH.D,再根据CH.D与LNA建立的线性相关方程估算检验样本的LNA,47个检验样本的实测LNA与估测LNA极显著线性相关（R = 0.8982**,n = 94）,模型方程的估算精度达86.3%,实测值与估算值的R_MSE = 1.0155,相对误差为0.1380。说明基于高光谱数据的棉花冠层叶绿素密度的遥感估测,可以间接用于棉花冠层叶片氮积累量的监测研究。     

利用高光谱技术估测大豆育种材料的叶面积指数

叶面积指数(LAI)是反映田间作物长势及产量潜力的重要参数,规模化育种要求及时、快速、无损地获取大量育种材料的田间生长信息。本研究利用52份大豆品种(系)的2年田间试验,在盛花期(R2)、盛荚期(R4)及鼓粒初期(R5)测定大豆冠层反射光谱,同步测定大豆LAI和地上部生物量(ABM)。结果表明,不同生育期LAI与冠层光谱在可见光波段(426~710 nm)均表现显著负相关(P0.05),在近红外波段(748~1331 nm)均表现为显著正相关(P0.05)。根据文献已报道的植被指数与LAI的线性相关性分析,NDVI和RVI类型的植被指数能够较好地指示大豆LAI,进而在全光谱250~2500 nm范围内涵盖上述两种类型的植被指数,经对建立的大豆LAI线性与非线性模型综合评价,遴选出不同生育期敏感植被指数的最优估测模型。其中,R2期RVI(825,586)所建模型(y=0.03x1.83)、R4期RVI(763,606)所建模型(y=0.38e0.14x)及R5期RVI(744,580)所建模型(y=0.06x1.79)的预测表现最好,决定系数(R2)分别为0.677、0.639和0.664,相对标准误(RRMSE)均小于20%;模型验证的决定系数(R2*)分别为0.643、0.612和0.634,均根方误差(RRMSE*)约20%。进而发现针对LAI和ABM的RVI共性核心波段组合为R2期的825 nm和586 nm、R4期的763 nm和606 nm以及R5期的744 nm和580 nm。本研究结果可望为大豆规模化育种中获取大量不设重复试验材料的田间长势信息提供快速无损预测的技术支持。     

基于近红外波段玉米叶绿素含量最佳预测模型研究

为了进一步探究近红外波段玉米光谱反射率与其叶绿素含量之间的关系,笔者采用线性和非线性法对玉米叶绿素含量与近红外波段光谱反射率及植被指数之间的关系进行分析,建立叶绿素含量最佳预测模型。结果表明：在近红外波段,光谱反射率与玉米叶绿素含量的相关性较大;叶绿素含量与RVI(R1001/R760)、RSI(R765/R720)、NDVI(R990-R760)/(R760+R990)、NDSI(R813-R763)/(R813+R763)、CCI(D794/D763)等植被指数均达极显著相关,其中与NDVI的相关性最大,为0.91。基于近红外波段的植被指数建立玉米叶绿素含量预测模型中,采用RVI、RSI、NDVI、NDSI所建的二次多项式模型其决定系数R2均高达0.75以上。采用990、760nm处的归一化植被指数NDVI建立的二次多项式为玉米叶绿素含量最佳预测模型,其具有最大决定系数(R2=0.855),较小RMSE(2.433)和RE%(0.61%),为利用高光谱信息反映玉米生长状况的叶绿素信息提供了基础。     

基于近地高光谱棉花生物量遥感估算模型

分析棉花地上鲜生物量冠层高光谱反射率变异系数，反射率光谱、一阶微分光谱与地上鲜生物量相关关系得结果表明：在可见光近红外波段棉花冠层反射率光谱变异系数在672 nm波段处最大；棉花地上鲜生物量与反射率光谱相关系数最大值在可见光波段出现在589~700 nm，在近红外波段出现在865~919 nm波段，且前者大于后者。地上鲜生物量与一阶微分光谱相关系数在可见光波段出现524~528 nm、552~588 nm、710~755 nm 3个高值区。基于以上研究，选择19个高光谱特征参数建立了棉花地上鲜生物量高光谱遥感监测模型，经检验，单波段中以F₆₂₉估算水平最高，估算模型为Y = 9.7914 exp(－20.738 F629)，准确度为83.9%、RMSE为0.64 kg m^-2、预测值与实测值相关系数为0.940**；组合参数以[629, 901]指数形式估算模型估算水平最高，模型为Y = 0.0986 exp(4.3696[629, 901])，准确度达84.0%，RMSE为0.55 kg m^-2，预测值与实测值相关系数为0.960**，上述两个模型为参选模型中估算棉花地上鲜生物量最佳高光谱估算模型。     

基于冠层反射光谱的夏玉米叶片氮积累量估测

为实现夏玉米冠层氮素状况的实时无损监测,于2009—2010年连续2个生长季,通过不同玉米品种和施氮水平下的田间试验,研究夏玉米叶片氮积累量与冠层反射光谱的相关关系,提出叶片氮积累量的敏感光谱参数,并建立叶片氮积累量的定量估算模型。结果表明,夏玉米叶片氮积累量随施氮水平的提高而增加;可见光波段的460~670 nm和近红外区的780~1100 nm是监测玉米叶片氮积累量变化差异的敏感波段;归一化植被指数(NDVI)、优化的简单比值指数(MSR)、优化土壤调节植被指数(OSAVI)、修正土壤调整植被指数(MSAVI)和土壤调整植被指数(SAVI)与叶片氮积累量相关性较好。利用不同年际独立试验数据对监测模型进行检验,以OSAVI为自变量构建的叶片氮积累量监测模型效果最优,相关系数(r)为0.6745,均方根差(RMSE)为1.2368。利用本研究确立的玉米叶片氮积累量与冠层反射光谱的定量关系,可用来定量估测叶片氮积累量的变化状况。     

基于机器学习算法的滴灌棉花地上部氮浓度估测模型研究

地上部氮浓度是准确诊断作物氮素丰缺进而评价其生长状况的重要指标。通过构建基于高光谱的滴灌棉花地上部氮浓度估测模型,实现棉花氮素含量的实时、无损、精确获取,为精准施肥提供理论依据和技术支撑。以新疆北部主栽棉花‘新陆早45号’和‘新陆早53号’为供试品种,设置6个施纯氮处理(0、120、240、348、360、480 kg/hm²),测量棉花冠层高光谱信息,利用函数变换去除冗余,一阶与二阶导数筛选结果相似,倒数的对数筛选结果较为分散。采用机器学习权重排序进行特征筛选,共选出359、371、751、752、746、739、755 nm等7个特征波段。同时遍历波长组合,优化前人研究与氮素高相关的植被指数,共选出RVI′_810,460、NDVI′_811,856、NDVI′_750,705、RVI′_740,720、RVI′_851,852、DVI′_359,360、NDVI′_851,852等7个光谱指数。将筛选得到的特征波段与植被...     

基于高光谱遥感的小麦条锈病胁迫下的产量损失估计

为利用高光谱遥感监测小麦条锈病,并对小麦条锈病胁迫下的产量损失进行估计,通过分析发生条锈病后的小麦冠层光谱及一阶微分的特征,分析病情指数对产量及产量构成因素的影响,分析产量和不同生育时期的光谱反射率及一阶微分光谱的相关关系,从中提取相关性高的植被指数和一阶微分参数建立产量模拟方程。结果表明,在一定范围内,产量损失随着病情指数的增大而增大,光谱反射率与产量在各个生育期都表现出稳定的显著正相关关系,从中提取相关性高的植被指数(NDVI和RVI)和一阶微分参数(SDr),利用植被指数(NDVI和RVI)建立的多时相产量模拟方程,其模拟效果较好;利用一阶微分参数(SDr)建立的不同生育时期产量回归方程,模拟的精度较高。研究结果对利用高光谱遥感监测作物病害胁迫下产量具有实际应用价值。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

Breeding forage grasses for organic conditions

Herbage yield trials are necessary to test if candidate varieties are well suited for organic conditions. In order to elucidate a particular suitability for organic conditions, we run such trials in parallel under both organic and conventional conditions. Here, we report on second and third year results of the sowings 2004 and 2005. These trials are part of a targeted breeding programme for organic conditions. Irregular colonisation of pure grass plots with adventitious plants, in particular white clover, was recognized as a major constraint to the quality of the results obtained under organic conditions. The coefficients of variance in dry matter yield almost doubled when compared to conventional trials, and significant differences in annual yield among varieties were rare. However, when herbage yield was corrected for the estimated fraction of adventitious plant colonization at each cut, the number of instances with statistically significant differences for annual yield among varieties increased more than fourfold. Dry matter yields under organic and conventional conditions were significantly and positively correlated. However, analysis of variance showed a significant culture type by variety interaction for annual dry matter yield in 12 out of 24 trials. When diploid and tetraploid varieties of the same Lolium species were tested in one common trial, only tetraploid varieties were identified as being particularly well suited for organic conditions, while in these trials, the great majority of apparently poorly suited varieties were diploid. This suggests that breeding tetraploid Lolium varieties is promising when aiming at a favourable response to organic agriculture.     

The performance of double or mixed pollinations with compatible and self-incompatible or incongruous pollen of pear and apple

Summary Six pear and five apple trials were carried out to ascertain the outcome of combinations of compatible pollen (C) with self (S) or incongruous pollen (I) as to the pollination index (PI=seeds/pollinated flower). The PI of the mixture C+I (1:5) was consistently depressed as compared to that of the control C. The results of the double pollinations S/C and I/C were affected by the temperature at pollination; their PI's at <15°C were twice as high as those at >15°C, being well above and below the PI of C in the former and latter case respectively. The opposite was true for the C/S combination, the PI of which increased with the pollination temperature; the PI of C/I did not differ much from the PI of C, irrespective of temperature. The conclusion was reached that the interaction previously and presently found between compatible and self-incompatible pollen also exists to a fair extent between compatible and incongruous pollen. However, in pear neither the mentor nor the pioneer pollen technique proved to aid its hybridization with apple, the formation of self seed was not observed either. In apple the production of apple × pear hybrids was likewise doubtful, but the double pollinations S/C and C/S formed 4–10% self seed.