Texture profiling of blueberries (Vaccinium spp.) during fruit development,ripening and storage

Blueberries are ‘soft fruit’, a name which underlies the impact that fruit texture plays in their marketability. Worldwide blueberry production has been increasing in the last years, and they are now the second most economically important soft fruit after strawberry. During pre- and postharvest ripening, fruit softening represents the most dramatic change, leading to important losses in quality during storage. To support the FEM breeding program toward the creation of new blueberry accessions with superior texture, we used a novel texture analyzer TAXTplus to improve the phenotyping resolution, a fundamental step for a more reliable and precise selection of the most suitable ideotypes. In this work change in the mechanical profile of the blueberry cultivar ‘Brigitta Blue’ was initially assessed during berry development, maturation and postharvest ripening, revealing important textural variations. In addition, this novel equipment was exploited to compare the fruit texture behavior at two specific stages, maturity and after postharvest cold storage, on a set of 49 different blueberry and hybrids cultivars and selections. A multivariate statistical approach, including principal component analysis, was employed to analyze the dataset related to the textural parameters, according to their performance. Finally a storage index, originally defined for apple fruit texture, was adopted to depict the different storage potential of a set of blueberry cultivars.     

Early‐stage screening for heat tolerance in cotton

The study aimed to identify early‐stage traits of cotton for heat tolerance using multitrait approach reflecting field yield performance. Seedling growth and physiological response of 16 cultivars to high temperature were investigated at three different developmental stages and four heat stress conditions in a climate chamber. Some traits such as hypocotyl dry weight, leaf pigment contents and cellular respiration were significantly correlated with previously known yield of ten cultivars grown in the hot field conditions. Sixteen cotton cultivars were classified for their heat tolerance by principle component analysis (PCA) using yield‐correlated physiological traits. As a result, we showed that heat tolerance classification of cultivars based on PCA significantly coincided with the yield results of cultivars grown in hot field. As a conclusion, yield‐correlated physiological traits determined in the study may facilitate selection of heat‐tolerant cotton genotypes at early stage. In addition, yield‐correlated early‐stage traits can be used in phenotyping for QTL and association mapping studies to develop selection markers for heat tolerance.     

可见/近红外光谱技术无损识别苹果品种的研究

为了能快速无损鉴别苹果的品种,基于高光谱成像技术结合模式识别算法,分别建立了判别苹果品种K最近邻(KNN)识别模型与偏最小二乘判别分析(PLS-DA)识别模型。综合比较了不同光谱预处理方法(二阶微分(SD)、标准正态变换(SNV)和多元散射校正(MSC))对各模型识别效果的影响,并利用主成分分析方法对预处理后的光谱数据进行降维,以提取能反映苹果品种的特征光谱。结果表明:采用主成分分析法选择了累计贡献率超过99.9%的前10个主成分作为样本集特征光谱数据,很好地实现了光谱数据的降维;MSC预处理方法对光谱反射率预处理的效果最好;2种判别模型均能基本满足实际要求,且MSC+KNN识别模型的识别性能最优,对预测集样本的正确识别率高达100%。     

Evaluation of grape flesh texture by an acoustic vibration method

Destructive acoustic vibrations produced by probe penetration were measured by a texture measurement device to clarify the characteristic flesh texture of nine grape cultivars and to examine methods for quantitative evaluation of grape flesh texture. The texture index (TI) is based on the energy density between 10 Hz and 3.2 kHz and was calculated using signals obtained with a piezoelectric sensor attached to a wedge-tipped probe. Using this index, we successfully classified nine grape cultivars according to flesh texture as crisp, non-crisp, or intermediate. The breaking force measured by a conventional puncture test did not identify these three types of texture. The breaking force was correlated with the TI calculated using 0-50 Hz vibrations but not with that calculated using the 10-3.2 Hz vibrations. This suggests that the former represents flesh firmness, and TI values measured at frequencies greater than 10 Hz evaluate characteristic textures of grape flesh that could not be evaluated using a load sensor installed in a conventional stress-strain analyzer.     

Importance of fruit variability in the assessment of apple quality by sensory evaluation

The assessment of produce quality is a major aspect of applied postharvest biology. Horticultural researchers working on organoleptic quality of fruit need objective methods for the evaluation of sensory properties. The development of sensory methodologies specifically for apples highlighted the problem of handling variation due to fruit variability and assessor differences. The aim of this study was to investigate the weight of within-batch variability in sensory evaluation of apples and to propose a methodology that accounts for this variability. Prior to sensory analysis, for three apple cultivars, apples were sorted into homogenous acoustic firmness categories within each cultivar. The discrimination ability of the trained panel was observed not only between cultivars but also within each cultivar for crunchiness, firmness, juiciness and acidity. Following these results, a mixed hierarchical model for the analysis of the sensory data was proposed to measure the contribution of fruit variability to the variability of sensory scores. The results showed the efficiency of the model in quantifying within-batch variability. Fruit sampling and presentation methods as well as data handling procedures are suggested for obtaining reliable sensory results in the assessment of apple quality.     

Sensory evaluation as a selection tool in apple breeding

Several conventional sensory methods were adapted to provide aprocedure that is suitable for screening apple (Malus × domestica) breeding selections for dessert quality. Trained judges were presented with randomized coded samples (apple slices) and asked to rate them on 0 to 9 bipolar hedonic (liking) scales for texture and flavour, and 0 to 9 unipolar intensity scales for skin toughness, crispness, hardness, juiciness, aroma, sweetness and sourness. Appearance liking was rated on coded samples of five whole apples, using the 0 to 9 hedonic scale. A minimum panel size of eleven judges was generally sufficient to obtain statistical discrimination of one point on the 0 to 9 scales. Panel mean scores for breeding selections relative to standards have been consistent from panel to panel and year to year. A subset of selections and cultivars was rated for appearance and taste by consumers in blind taste tests. In-house panel findings were comparable to consumer ratings for taste and appearance liking, with a few exceptions in appearance. Panel mean scores for texture and flavour liking were regressed on texture and flavour components. Crispness accounted for about 90% of the variation in texture liking. Juiciness, aroma, sweetness and sourness were all important to flavour liking, but their relative importance changed from year to year and in total accounted for only about 60% of variation in flavour liking. Perceived sweetness and sourness were better predictors of liking than analytical measurements of soluble solids and titratable acidity. Formal sensory evaluation can be used successfully for screening breeding selections, and may provide more reliable data than the opinions of only one or two people.     

基于种子图像处理的大数目玉米品种形态识别

玉米种子鉴别是种子质量检验和育种实践的重要内容。为了评价通过图像处理采集种子特征进行大数目品种鉴别的可行性, 扫描了193个品种各50粒种子图像, 建立和检验了由4大类46个种子形态特征及其组合组成的6种识别模型。大小类、形状类、纹理类、颜色类、后3类组合、全部4类组合等模型的品种检出率分别为25%、33%、39%、95%、95%和95%, 平均籽粒拒真率分别为90%、90%、86%、45%、47%和42%, 认伪率为92%、92%、88%、46%、48%和43%, 且后两个误判率高度正相关(r = 0.83**~ 0.91**)。机器视觉检测具有成本和速度上的优势, 能够用于大数目玉米品种的真伪鉴定, 形状+纹理+颜色组合模型最佳, 经改进技术识别率可以进一步提高。     

Molecular characterisation of cultivars of apple (Malus × domestica Borkh.) using microsatellite (SSR and ISSR) markers

In this study, two microsatellite-based methodologies (SSR and ISSR) were evaluated for potential use in fingerprinting and determination of the similarity degree between 41 commercial cultivars of apple previously characterised using RAPD and AFLP markers. A total of 13 SSR primer sets was used and 84 polymorphic alleles were amplified. Seven ISSR primers yielded a total of 252 bands, of which 176 (89.1%) were polymorphic. Except for cultivars obtained from somatic mutations, all cultivars were easily distinguishable employing both methods. The similarity coefficient between cultivars ranged from 0.20 to 0.87 for SSR analysis and from 0.71 to 0.92 using the ISSR methodology. Dendrograms constructed using UPGMA cluster analysis revealed a phenetic classification that emphasises the existence of a narrow genetic base among the cultivars used, with the Portuguese cultivars revealing higher diversity. This study indicates that the results obtained based on the RAPD, AFLP, SSR and ISSR techniques are significantly correlated. The marker index, based on the effective multiplex ratio and expected heterozygosity, was calculated for both analyses (MI = 1.7 for SSR and MI = 8.4 for ISSR assays) and the results obtained were directly compared with previous RAPD and AFLP data from the same material. The SSR and ISSR markers were found to be useful for cultivar identification and assessment of phenetic relationships, revealing advantages, due to higher reproducibility, over other commonly employed PCR-based methods, namely RAPD and AFLP. This revised version was published online in August 2006 with corrections to the Cover Date.     

Screening fruit tree genetic resources in Belgium for disease resistance and other desirable characters

Summary The wide diversity of old fruit-tree cultivars originating or introduced into Belgium during the 18 ^th and 19 ^th centuries was collected as far as feasible over the last fifteen years at the State Plant Pathology Station in Gembloux. Out of the 2400 accessions now collected, one quarter was recovered from old public collections, and three quarters came from farms or gardens. The initial intention was to screen the material for disease resistance and other characters of agronomic interest with a view to using the best cultivars as breeding parents. However, as the collection developed, genetic resources conservation also became an objectiveper se. The collection presently contains 1150 apple, 850 pear and 300 plum accessions, and smaller numbers of other fruit species. Each accession is evaluated in an experimental orchard for at least ten years. In view of the growing public interest in old fruit-tree cultivars, the Plant Pathology Station has for several years been releasing to the nursery trade the better cultivars emerging from the evaluation, namely nine apple and four plum cultivars, and one peach cultivar. The principal features of the apple cultivars are presented in this paper. Since 1988, old apple and plum cultivars have been being used at the Station as parents in a breeding programme, with both controlled and open pollination. In some instances, old apple cultivars have also been crossed with a modern parent carrying the Vf gene for scab resistance. The preliminary observations on some of these seedlings are presented.     

Comparing RAPD and AFLPTM analysis in discrimination and estimation of genetic similarities among apple (Malus domestica Borkh.) cultivars

Forty-one apple (Malus × domestica Borkh.) cultivars were screened for RAPD (Random Amplified Polymorphic DNA) and AFLP(Amplified Fragment Length Polymorphism) markers. RAPD analysis was performed with 35 arbitrary 10-mer primers, selected from 60 primers tested (kits A, C and E, Operon Technologies, Inc.). Of a total of 362bands observed, 208 (57.5%) were polymorphic. Three-hundred-and-eighty-one AFLP fragments were obtained with 8primer combinations, of which 218 (57.2%) were polymorphic. Cultivars differentiated through mutation were included in this study and showed identical patterns when analysed with both RAPD and AFLP analysis. The estimated genetic relationships were correlated (r = 73.7%) between the analysis with the two different markers. UPGMA analysis was performed and dendrograms were constructed using either the data apart from each(RAPD and AFLP) method or combined in a single joint matrix. The relationships among the forty-one studied cultivars were basically consistent with the known lineage and geographic origins of the cultivars. The four Portuguese cultivars included in this study clustered together and diverged from the other cultivars. Apparently they constitute an independent genetic pool, which could be of interest for apple plant breeders. This revised version was published online in July 2006 with corrections to the Cover Date.     

电子鼻评价甜瓜成熟度及风味的研究

本文探讨了采用电子鼻系统对不同品种资源和成熟度的甜瓜进行分析测定。通过主成分分析(PCA) 和线性判别式分析(LDA)表明采用电子鼻可以很好区分半熟期和完熟期的甜瓜。当采用PCA 方法分析时, 电子鼻可以100%地区分和判定不同成熟度的甜瓜。对不同品种甜瓜进行电子鼻检测的研究表明,电子鼻可以区分不同品种的甜瓜,区分力值很高。样品在切开和不切开状态下气味有所变化,导致各品种之间的区分力有所改变。对于某些在不切开状态下香气非常接近,难以区分的样品,可以考虑通过切开的方式对样品进行分析。通过本研究建立了一种快速准确的判读不同品种甜瓜的成熟度,改变以往仅通过人为的主观判断方式。     

菠萝17份种质的ISSR分析

利用ISSR分子标记技术对17份菠萝种质进行了基因组DNA多态性分析。从62个ISSR引物中筛选出6个多态性引物用于PCR扩增，共扩增出70条DNA条带，其中多态性条带44条，所占比例为62.86%，平均每个引物扩增的DNA条带的数目为11.67条。6个品种具有特异性的扩增带，可作为种质鉴定的依据。根据ISSR扩增结果建立的UPGMA聚类图，在距离系数约0.1处可把供试的17份菠萝种质分为3大类。同时对供试品种的遗传关系进行了探讨     

Low cost measurement setup based on a piezoelectric microphone for estimating apple bruising using Shannon entropy

This study presents a low cost measurement setup for estimating apple bruise volume during drop impact tests. The proposed measurement system consists of three main stages namely recording impact sound, signal processing, and estimating bruise volume. In the recording stage, the impact sound occurred when striking the apple on the surface was recorded by a piezoelectric microphone into computer. The impact sound was converted into Shannon entropy signals based on the Kernel density approach, and two measurable quantities namely entropy peak and pulse-width time were extracted from Shannon entropy signals in the signal processing stage. In the bruise volume estimating stage, the regression curves that map entropy peak and pulse-width features into bruise volume are estimated using measurements data. To evaluate the performance of the proposed method, we conducted several drop experiments with six different drop heights and two different temperatures (1 and 19 °C). Experimental results showed that bruise volume was exponentially proportional to the entropy peak and it was inversely proportional to pulse-width time as power functions, and all the curves were fitted with coefficients of determination of more than 0.98. Moreover, it was found that colder apples developed less bruise volume then warmer ones.     

Venturia inaequalis resistance in local Spanish cider apple germplasm under controlled and field conditions

Host resistance is a key method for the integrated management of apple scab caused by Venturia inaequalis, which is one of the most important diseases of apple. Artificial inoculation of 92 cider apple cultivars with a mixed inoculum of V. inaequalis identified 19 weakly resistant and 19 resistant cultivars. Twelve of these resistant cultivars were previously classified as having low susceptibility to fire blight, and four of them showed complete or weak resistance to races (1), (1, 6) and (6, 7, 13) of V. inaequalis. The analysis of a selection of 72 cultivars for 6 years under field conditions identified 14 cultivars that were classified as resistant to apple scab under high disease pressure involving one to six Mills periods of severe risk of infection each year. Eight out of these 14 cultivars previously showed high levels of resistance to fire blight, which would allow the incorporation of genetic resistance in the integrated production of cider apples in Spain through their use in breeding programs.     

Effects of soil drought during the vegetative phase of seedling growth on the uptake of 14co2 and the accumulation and translocation of 14C in cultivars of field bean (vicia faba L. Var. Minor) and field pea (pisum sativum L.) Of different drought tolerance

During the vegetative phase of growth of two field bean and two field pea cultivars of different drought tolerance, the effect of short and prolonged soil drought on gas exchange (CO₂ i H₂O), leaf water potential (ψ), stomatal diffusive resistance (r_S), uptake of CO₂, and the distribution and accumulation of ¹⁴C was studied. Differences in the response to drought conditions between resistant and susceptible cultivars were marked. After 5 days of soil drought, the decrease in net photosynthesis and transpiration rate and the increase of stomatal resistance were greater in the drought-resistant cultivars than in the drought-susceptible ones. In contrast, after 10 days of drought the decrease of leaf P_N (CO₂ assimilation rate), E (rate of transpiration) and ψ (water potential) was greater in the susceptible cultivars than in the resistant ones. Significant differences between the resistant and the susceptible cultivars were also observed in the assimilation and translocation of ¹⁴C by the green parts of the plant. The amount of carbon accumulation in roots in drought-susceptible cultivars increased less than in the drought-resistant cultivars. For treatments in which optimal soil watering was resumed after 5 or 10 days of drought there was no evidence of effects of drought on the majority of measurements, but the drought-resistant cultivars showed a general tendency for a more rapid recovery. Our results confirm the existence of genetic variability in drought tolerance among the cultivars of field bean and field pea. The recorded differences in the response to drought of experimental cultivars may indicate that, under water deficit in the soil and in plant tissues, they may use different strategies to avoid the damaging effects of temporary limitation of water supply; for example, the drought-resistant cultivars may more effectively conserve tissue hydration through effective stomatal closure. Also, the observed changes in carbon assimilation and accumulation might be the reason for their different responses to drought. The change in radioactivity losses in the control and stressed plants may result from the differences in demand for energy to maintain cell structure and function. Similarly, the less intense carbon accumulation in the roots of the sensitive cultivars could be caused by more harmful effects of drought on root growth.     

The use of a modified bulk segregant analysis to identify a molecular marker linked to a scab resistance gene in apple

Almost two-hundred random sequence decamer-primers were used to screen a pair of bulked samples and the donor parent Malus floribunda clone 821 for markers linked to the V_f gene conferring resistance to apple scab (Venturia inaequalis (Cke.) Wint.). A single primer was identified which generated a PCR fragment, OPK16/1300, from the donor parent M. floribunda clone 821 and the scab-resistant selections/cultivars bulk, but not from the scab-susceptible recurrent parent bulk. Co-segregation analysis using a segregating apple progeny and polymorphism analysis of individual scab-resistant Coop selections/cultivars confirmed that this marker was linked to the scab-resistance gene V_f with a recombination frequency of 4.3%. OPK16/1300 was then cloned and sequenced. Sequence-specific primers of 25 oligonucleotides based on the marker were synthesized, and used in turn to screen M. floribunda clone 821, scab-susceptible apple cultivars, scab-resistant apple cultivars, and scab-resistant Coop selections. A pair of sequence-specific primers of clone OPK16/1300 amplified a distinct single band of the same size as the RAPD clone. Thus, a sequence characterized amplified region (SCAR) marker was developed which can be used to identify polymorphisms of OPK16/1300 based on the presence or absence of a single band. This revised version was published online in July 2006 with corrections to the Cover Date.     

Breeding aspects of clustering winter wheat cultivars for yield response

The objective of this study was to compare the yield response of several present day winter wheat cultivars of different origin with the aim of broadening breeders' information from multi-year/location tests by using an appropriate cluster procedure. Yield response of 18 cultivars was analysed using data from two series of official yield performance tests in Germany. Similarity of yield response between two cultivars is defined by a positive correlation coefficient (nearly one) for the yields over all test environments. A hierarchical agglomerative procedure was used to establish clusters of similarly responding cultivars. The smallest distances in yield response were established between closely related cultivars of equal maturity. Clusters of cultivars with distinct maturity and also the groups of East and West German cultivars tested exhibited clear differences in yield response.