Detection of early apple bruises using pulsed-phase thermography

The study is based on a hypothesis that internal defects and physiological disorders of fruit lead to changes in tissue thermal properties. During thermal stimulation, heterogeneities of thermal properties lead to the occurrence of thermal contrasts on the surface of fruit material, which can be successfully registered with the use of a thermographic device. A method was developed to detect apple bruising early using pulsed-phase thermography (PPT). In PPT the studied object is heated with an individual thermal pulse (most frequently a rectangular pulse) and the temperature decay on the surface is analysed on a pixel-by-pixel basis as a mixture of harmonic waves, thus enabling the computation of phase and amplitude images. The fast Fourier transform was used to obtain ampligrams and phasegrams of fruit heat response to defects occurring at different depths. The automatic segmentation procedure made it possible to select areas of bruised tissue in thermograms. A comparison of PPT results and visual inspection of bruising was performed, indicating high possibilities of the active thermography method for detecting defects up to several millimetres.     

Supervised classification of bruised apples with respect to the time after bruising on the basis of hyperspectral imaging data

Apple bruising, as a mechanical damage, occurs due to impact, compression, vibration or abrasion during handling. However, the symptoms of this damage, browning and softening of the tissue, appear not immediately but after a certain period of time after bruising. For sorting and grading systems, the information about how long the bruise exists in affected fruit can be valuable. VNIR (visible and near-infrared) and SWIR (short wavelength infrared) spectral characteristics of sound and bruised apple tissues were analyzed during a two week period after bruising. Supervised classification methods, including support vector machines, linear logistic regression, neural networks and decision trees, were used and compared to check their effectiveness for distinguishing time after bruising with respect to five varieties of apples. The detection system included hyperspectral cameras equipped with sensors working in the visible and near-infrared (400–1000 nm) and short wavelength infrared (1000–2500 nm) ranges. The results of supervised classification revealed good applicability of hyperspectral imaging in VNIR and SWIR spectral ranges for detecting the number of days after bruising. The linear logistic regression neural networks models were found to be the best classifiers in the majority of models developed. Prediction accuracies higher than 90% were obtained for classification models on spectral data pretreated with the second derivative.     

Assessment of apple (Malus × domestica Borkh.) fruit texture by a combined acoustic-mechanical profiling strategy

Texture of apple fruit originates from anatomic traits related to cell wall architecture and is one of its most important quality characteristics, thus there is the desire to better understand the different factors which contribute to apple texture. Here we present a novel approach based on the simultaneous profiling of the mechanical and acoustic response of the flesh tissue to compression, using a texture analyzer coupled with an acoustic device. The methodology was applied to a 86 different apple cultivars, measured after two months postharvest cold storage and characterised by 16 acoustic and mechanical parameters. Statistical treatment of the data with principal component analysis (PCA) allowed for the identification of three groups of variables, the mechanical ones being clearly distinguished from the acoustic ones. Moreover, the distribution of the apple cultivars in the multivariate PCA plot allowed characterisation of the cultivars according to their textural performance. Each cultivar was analyzed also with non-destructive vis/NIR spectroscopy in order to determine impartially the ripening stage. Sensory evaluation by panellists was performed on a selected group of cultivars and sensory data correlated with the acoustic-mechanical data. The results demonstrate the good performance of our combined acoustic-mechanical strategy in measuring apple crispness as it is perceived by human senses.     

苹果不同生育期综合气象资源对产量的影响研究——以天水市秦州区为例

为定量确定综合气候资源对苹果产量的影响,运用1981—2010 年秦州区苹果单产资料及苹果主要生育期（4—8 月）平均气温、降水量、日照时数资料,建立了综合气象资源指数,分析了苹果不同生育阶段气候因子的变化规律及对苹果产量的影响。结果表明,近30 年苹果生长前期的热量因子的变化幅度大于生长后期。坐果之前,开花时的低温冷害对苹果产量影响较大。苹果前期生长阶段（4—6 月）降水量呈下降趋势,后期生长阶段（7—8 月）降水量线性变化趋势不明显。后期降水量与产量相关性明显。苹果前期生长阶段（4—6 月）日照时数为随时间呈上升趋势,后期生长阶段（7—8 月）日照线性变化趋势不明显。综合资源指数与苹果产量的变化有较好的一致性。20 世纪90 年代,综合气候资源不利于苹果产量的形成,从21 世纪初综合气候资源指数开始增加,苹果产量也开始上升。未来气候变化趋势利于苹果生产。     

陕西苹果花期预测模型研究

为了增强陕西各苹果产区精确防御花期冻害的能力,有效提高苹果产量和品质,促进陕西苹果产业稳定、持续、健康发展,依据统计分析原理,对陕西各苹果产区花期和花期前的各项气温因子进行详细的相关性分析。结果显示：陕西苹果花期前0~5℃的活动/有效积温与真实花期的相关性好于0~5℃天数与真实花期的相关性;0~5℃的活动/有效积温越靠近真实花期,其与真实花期的相关性越显著;从0℃至5℃各活动/有效积温与苹果花期的相关性呈增高趋势;各有效积温因子与苹果花期相关性好于活动积温因子与苹果花期的相关性。基于以上分析结果,分果区建立了陕西苹果的花期预测模型,并通过回代和预测对模型进行检验。检验结果显示平均误差小于3天,预测结果可为实际生产中苹果花期防灾减灾工作的开展提供参考。     

Advances in QTL mapping for ethylene production in apple (Malus × domestica Borkh.)

Ethylene is a gaseous hormone that coordinates several important physiological processes resulting in the final fruit quality in apple. Due to its genetic heterozygousity, apple offers the possibility to exploit the natural allelic variation existing at the level of two genes involved in the ethylene biosynthetic pathway, Md-ACS1 and Md-ACO1. The allelism of these two genes can be exploited for the advanced selection of genotypes characterized by low ethylene production, with a consequent extended postharvest storability. The impact of these two elements in ethylene control was verified using two specific apple populations (‘GDxBr’ and ‘FjxMG’) presenting distinct allelotype configurations. In the first progeny, two QTLs were identified in genetic positions corresponding with these genes, and for the first time the association of a QTL for ethylene production with Md-ACO1 in apple was established. However, the analysis carried out on the second population, homozygous for the allele of Md-ACS1 associated with a low ethylene production, suggested the possible involvement of other genetic elements in the regulation of ethylene production. In the end we also present, in parallel to the GC assessment, a novel methodology based on proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) for a more reliable, fast and efficient monitoring of the ethylene production in apple.     

基于县域单元的降尺度苹果花期冻害风险区划

为了有效利用气候资源,趋利避害,合理规划和发展陕西苹果产业;同时促进县域苹果种植布局优化,健康、可持续生产,依据5个苹果种植代表县县站与其境内区域站花期气温的关系,进行概率移植,借助各代表县县站1971—2012年花期气温数据,计算获得各代表县县站及其境内区域站苹果不同等级花期冻害的发生概率。根据对100多个历史灾害个例的分析结果,分别赋予苹果花期轻度、中度、重度等级冻害0.1、0.3、0.5的灾损系数。依据气候致灾风险的基本原理和模型,计算获得各代表县县站及其境内区域站的花期冻害风险指数,并基于GIS系统制作了各代表县的降尺度苹果花期冻害风险分布图。     

气候变化对不同产区苹果安全越冬的可能影响

为科学评估气候变化对中国产区苹果安全越冬的影响,结合现有成果提出了分别表征果树初冬低温伤害风险、冬季持续性低温伤害风险、冬季极端低温危害风险和脱驯化期的低温伤害风险4个农业气象指标,利用1961—2015年中国苹果主产区的气象资料,分黄土高原、环渤海湾、黄河故道、西南高地和新疆5个产区,评估了气候变化对苹果安全越冬的可能影响。结果表明：苹果产区越冬期升温明显,霜冻日数和极端低温事件发生频次显著减少。初冬首次低温与初霜日间隔缩短导致渤海湾北部产区、黄河故道及北疆苹果的初冬低温伤害风险增加。越冬期持续性低温伤害风险和极端低温危害风险总体降低,特别是中高纬度表现明显,而黄土高原和新疆产区的极端低温事件发生的不确定性较大。同时黄土高原、辽宁、川西和北疆等产区苹果脱驯化期的低温伤害风险有所增加。总体上,苹果深度休眠期的冬季极端低温和持续性低温冻害风险有所降低,而初冬和脱驯化期低温冻害风险显著增加。     

Application of MRI for tissue characterisation of ‘Braeburn’ apple

Magnetic resonance imaging (MRI) has become a well-established technique for non-destructive analysis of the internal (micro)structure of food, and the related heat, gas, water and solutes transport, which is of interest for food processing (e.g., drying), physical tissue damage assessment (e.g., bruising) for online sorting purposes or detection of internal defects (e.g., internal browning), amongst others. In contrast to previous MRI studies which predominantly analysed entire fruit, small samples (diameter ∼10⁻² m) of ‘Braeburn’ apple were investigated in this study with high-field MRI, providing very local, high-resolution information, in order to identify the capability of MRI for detecting differences in fruit tissue types. The focus was on MRI for tissue characterisation with respect to inner and outer cortex tissue, fertilisation treatment, storage time and internal browning (IB). For this purpose, the proton density (PD), T₂ value and self-diffusion coefficient (DC) were measured. No clear distinction could be made between samples with different fertilisation treatments. Differences in storage times could be observed from an increased PD for longer storage times. Inner tissue clearly showed an increased PD, T₂ value and DC, compared to the outer tissue. IB could be successfully detected, where the PD, T₂ value and the DC of the affected tissue were clearly higher than those of the healthy tissue, but a dependency of these parameters on the degree of tissue degradation was identified. Especially, the DC seemed to be an appropriate parameter regarding IB detection.     

Automatic detection of common surface defects on oranges using combined lighting transform and image ratio methods

Automatic detection of fruit peel defects by a computer vision system is difficult due to the challenges of acquiring images from the surface of spherical fruit and the visual similarity between the stem-ends and the true defects. In this study, oranges with wind scarring, thrips scarring, scale infestation, dehiscent fruit, anthracnose, copper burn, canker spot and normal surface were researched. A lighting transform method based on a low pass Butterworth filter with a cutoff frequency D₀ = 7 was first developed to convert the non-uniform intensity distribution on spherical oranges into a uniform intensity distribution over the whole fruit surface. However, the stem-ends were easily confused with defective areas. In order to solve this problem, different color components (R, G and B) and their combinations were analyzed. It was found that a ratio method and R and G component combination coupled with a big area and elongated region removal algorithm (BER) could be used to differentiate stem-ends from defects effectively. Finally, a processing and classification algorithm based on a simple thresholding method was proposed. The result with 98.9% overall detection rate for the 720 independent sample images indicated that the proposed algorithm was effective in differentiation of normal and defective oranges. The method, however, could not discriminate between different types of defects.     

Preliminary results of differentiating apple sports by pollen ultrastructure

The pollen grain surface morphology of two Red Delicious apple (Malus × domestica Borkh.) sports, Aversang and Ultrared, and two Gala apple sports, Galalea and Splenola, were examined using scanning electron microscopy for genotype differentiation. Quantitative data on pollen dimensions, ridge patterns, and pore dimensions were extracted from micrographs using image analysis. Data were examined with analysis of variance, canonical variate analysis, and discriminant analysis in order to differentiate genotypes. The combination of image analysis to extract quantitative data and multivariate analysis was successful in differentiating apple sports with exine pore and pollen grain measurements. This revised version was published online in July 2006 with corrections to the Cover Date.     

Assessment of watercore development in apples with MRI: Effect of fruit location in the canopy

Watercore distribution inside apple fruit (block or radial), and its incidence (% of tissue) were related to the effect of solar radiation inside the canopy as measured by a set of low-cost irradiation sensors. 221 samples were harvested in two seasons from the top and the bottom of the canopy and submitted to the non-invasive and non-destructive technique of magnetic resonance imaging (MRI) in order to obtain 20 inner tomography slices from each fruit and analyze the damaged areas using an interactive 3D segmentation method. The number of fruit corresponding to each type of damage and the relevant percentage were calculated and it was found that apples from the top of the tree were mainly of the radial type (84%) and had more watercore (approx. 5% more) than apples from the bottom (65% radial). From the image segmentation, the Euler number, a morphometric parameter, was extracted from the segmented images and related to the type of watercore symptoms. Apples with block watercore were grouped in Euler numbers between −400 and 400 with a small evolution. For apples with radial development, the Euler number was highly negative: up to −1439. Significant differences were also found regarding sugar composition, with higher fructose and total sugar contents in apples from the upper canopy, compared to those in the lower canopy location. In the seasons studied (2011 and 2012), significantly higher sorbitol and lower sucrose and fructose contents were found in watercore-affected tissue compared to the healthy tissue of affected apples and also compared to healthy apples.     

苹果组培苗移栽过程中根茎叶解剖结构变化

系统全面地研究‘嘎拉'苹果组培苗移栽过程中根茎叶的解剖形态变化,为今后的组培苗移栽提供一定的理论依据和技术支持。采用石蜡切片法和扫描电镜法对苹果试管苗驯化移栽过程中根茎叶的解剖结构进行观察。随着移栽时间的延长,根的木质部和韧皮部逐渐分化,在维管柱中央形成若干排列成链的导管。茎的厚角组织细胞层数逐渐增多,细胞排列变得整齐紧密。茎的维管束逐渐形成环状条带,条带的厚度不断增加。苹果组培苗驯化移栽初期,叶片的栅栏组织发育不完全,海绵组织细胞间隙大,栅栏组织和海绵组织厚度比很低,仅为0.41。随着移栽时间的延长,叶片的栅栏组织和海绵组织分化发育逐渐完善,栅栏组织的细胞层数明显增加且细胞排列整齐紧密,海绵组织细胞间隙逐渐变小,栅栏组织和海绵组织厚度比变大。移栽3周后,栅栏组织和海绵组织厚度比为0.74。气孔的形态由移栽初期的突出于表皮细胞之上变为下陷于表皮细胞之下,气孔的开张度和气孔密度均逐渐变小。苹果组培苗移栽3周后其气孔密度下降为187个/mm²,这与移栽初期的气孔密度252个/mm²差异显著。苹果组培苗驯化移栽过程中,苹果组培苗根茎的主要变化是维管束组织的形成和健全,叶的变化是向着光合能力的提高和防止水分过度散失的方向发展。     

外源抗氧化剂对高温强光胁迫下苹果果皮组织抗氧化特性的影响

研究了在高温胁迫下,以不同种类外源抗氧化剂处理,对苹果果皮组织抗坏血酸过氧化物酶、超氧化物歧化酶的活性和维生素C含量的影响,实验结果表明高温胁迫下抗坏血酸过氧化物酶、超氧化物歧化酶的活性和维生素C含量有显著提高,说明施用抗氧化剂后苹果果皮组织抗氧化能力提高,尤其是施用复合抗氧化剂效果更明显。     

Development of high-density interspecific genetic maps for the identification of QTLs conferring resistance to <Emphasis Type="Italic">Valsa ceratosperma</Emphasis> in apple

Valsa canker (Valsa ceratosperma (Tode ex Fr.) Maire) is one of the most destructive fungal diseases of apple, especially in Eastern Asia. In this study, the first high density genetic linkage map of Malus asiatica × Malus domestica was constructed by 640 simple sequence repeats (SSRs) and 490 single nucleotide polymorphisms (SNPs), which spanned 1497.5 cM with an average marker interval of 1.33 cM per marker. Quantitative trait loci (QTLs) for apple’s resistance to V. ceratosperma isolates 03-8 and xc56 were identified using the linkage map. Lesion lengths were used as the phenotypic data for the QTL analysis, which were measured on 1-year-old shoots inoculated with conidia of the two isolates. One QTL for resistance to isolate 03-8 was mapped on LG 16, and one QTL for resistance to isolate xc56 was detected on LG 9. Our research not only promoted the further understanding of the genetic basis of apple’s resistance to Valsa canker but also provided two molecular markers that might be used in future marker-assisted selection for resistance in apple breeding programs.     

Overexpression of BpMADS4 from silver birch (Betula pendula Roth.) induces early-flowering in apple (Malus × domestica Borkh.)

To shorten the juvenile stage of apple (Malus × domestica Borkh.) the BpMADS4 gene from silver birch (Betula pendula Roth.) was constitutively overexpressed in 25 transgenic apple clones. All clones were characterized by PCR, RT‐PCR and Real Time PCR. Solitary flowers were produced on in vitro shoots of eight transgenic clones and most of them appeared to be morphologically normal. Twenty shoots of each clone were rooted and transferred to a glasshouse. Glasshouse plants of clones T1165, T1187 and T1190 developed flowers. Several plants of T1165 and T1187 started floral initiation within 3–4 months following transfer to the glasshouse. Primary flowers were solitary and in a terminal position on the main shoot. Lateral flower clusters, consisting of three to five individual flowers, were also found. Pollen vitality and tube germination of glasshouse‐grown flowers were investigated, and there were no significant differences compared to pollen of non‐transgenic control plants. Preliminary crosses using flowers of glasshouse plants resulted in small apple fruits. It would seem that this is the first report on in vitro flower induction in transgenic apple.     

细胞壁降解酶在苹果霉心病菌致病过程中的作用研究

为明确细胞壁降解酶在苹果霉心病菌致病过程中的作用,以‘红星’苹果为材料,研究了活体内外霉心型致病菌链格孢菌(Alternaria alternata)和心腐型致病菌粉红单端孢菌(Trichothecium roseum)细胞壁降解酶的活性,以及使用商业酶处理后苹果的发病情况。结果表明：在不同碳源物质诱导下两种病原菌细胞壁降解酶变化不同。苹果细胞壁粉对粉红单端孢菌滤纸酶活性诱导的最高。而链格孢菌滤纸酶活性在纤维素粉和细胞壁粉诱导下明显高于其他处理(P<0.05)。两个致病菌的羧甲基纤维素酶均在细胞壁粉诱导下活性最高(P<0.05)。粉红单端孢菌的β-葡萄糖苷酶在果肉中诱导活性最高。链格孢菌β-葡萄糖苷酶在果肉和纤维素粉中诱导活性最高。β-葡萄糖苷酶和纤维素酶这两种致病酶只在发病苹果的病健界处明显升高(P<0.05)。纤维素酶和葡萄糖苷酶接种3d了苹果后发病面积分别为2.46 cm2和0.75 cm2(图8),而症状与致病菌接种后相似。上述结果表明纤维素酶和葡萄糖苷酶这两种致病酶在苹果霉心病病原菌致病过程中起重要作用,特别是纤维素酶。     

Characterisation of resistance to crenate broomrape (<Emphasis Type="Italic">Orobanche crenata</Emphasis> Forsk.) in <Emphasis Type="Italic">Lathyrus cicera</Emphasis> L.

Field, pots and mini-rhizotrons experiments revealed the existence of useful levels of avoidance and resistance to Orobanche crenata Forsk. within Lathyrus cicera L. accessions, in addition to escape due to precocity or to reduced root biomass. This resistance was characterized by several phenotypic mechanisms of defence which acted alone or in combination, including low stimulation of parasitic seed germination, prevention of the radicle penetration inside the root and prevention of a correct connection by the parasite with the host vascular tissue being visible by reduced development of established parasitic tubercles or abortion of the parasitic tubercles formed.