A method of detecting apple leaf diseases based on improved convolutional neural network.

Apple tree diseases have perplexed orchard farmers for several years. At present, numerous studies have investigated deep learning for fruit and vegetable crop disease detection. Because of the complexity and variety of apple leaf veins and the difficulty in judging similar diseases, a new target detection model of apple leaf diseases DF-Tiny-YOLO, based on deep learning, is proposed to realize faster and more effective automatic detection of apple leaf diseases. Four common apple leaf diseases, including 1,404 images, were selected for data modeling and method evaluation, and made three main improvements. Feature reuse was combined with the DenseNet densely connected network and further realized to reduce the disappearance of the deep gradient, thus strengthening feature propagation and improving detection accuracy. We introduced Resize and Re-organization (Reorg) and conducted convolution kernel compression to reduce the calculation parameters of the model, improve the operating detection speed, and allow feature stacking to achieve feature fusion. The network terminal uses convolution kernels of 1 × 1, 1 × 1, and 3 × 3, in turn, to realize the dimensionality reduction of features and increase network depth without increasing computational complexity, thus further improving the detection accuracy. The results showed that the mean average precision (mAP) and average intersection over union (IoU) of the DF-Tiny-YOLO model were 99.99% and 90.88%, respectively, and the detection speed reached 280 FPS. Compared with the Tiny-YOLO and YOLOv2 network models, the new method proposed in this paper significantly improves the detection performance. It can also detect apple leaf diseases quickly and effectively.

Morphological, sensory and biochemical characteristics of summer apple genotypes / Características morfológicas, sensoriais e bioquímicas de genótipos de maçã cultivada no verão

Summer apples are one of the most important plant community in Artvin province located Northeastern part of Turkey. In present study 22 local apple genotypes were characterized by phenological, morphological, biochemical and sensory properties. Harvest date was the main phenological data. Morphological measurements included fruit weight, fruit shape, fruit ground color, fruit over color, fruit over color coverage and fruit firmness, respectively. Sensory measurements were as juiciness and aroma and biochemical characteristics included organic acids, SSC (Soluble Solid Content), vitamin C, total phenolic content and antioxidant capacity. Genotypes exhibited variable harvest dates ranging from 11 July to 13 August and cv. Summered harvested 30 July 2017. The majority of genotypes were harvested before cv. Summered. Fruit weight were also quite variable among genotypes which found to be between 89 g and 132 g, and most of the genotypes had bigger fruits than cv. Summered. Pink, red, yellow and green fruit skin color was evident and main fruit shape were determined as round, conic and oblate among genotypes. ART08-9, ART08-4, ART08-21 and ART08-22 had distinct bigger fruits and ART08-1, ART08-2, ART08-5, ART08-12 and ART08-17 had higher total phenolic content and antioxidant capacity. The results of the study showed significant differences for most of the phenological, morphological, sensory and biochemical characteristics. Thus, the phonological, morphological, sensory and biochemical characteristics of summer apple genotypes were distinguishable and these results suggest that phonological, morphological, sensory and biochemical differences of the summer apple genotypes can be attributed to differences in genetic background of genotypes which placed different groups by PCoA analysis.

As maçãs cultivadas no verão são uma das culturas vegetais mais importantes da província de Artvin, localizada no nordeste da Turquia. No presente estudo, 22 genótipos locais de maçã foram caracterizados quanto às suas propriedades morfológicas, bioquímicas e sensoriais. As características analisadas foram peso do fruto, data da colheita, forma do fruto, coloração da casca, firmeza do fruto, suculência, aroma, teor de ácidos orgânicos e de sólidos solúveis, vitamina C, teor fenólico total e capacidade antioxidante. Os genótipos exibiram datas de colheita que variaram de 11 de julho a 13 de agosto, e a cultivar de verão foi colhida em 30 de julho 2017. A maioria dos genótipos foi colhida antes da cultivar de verão. O peso dos frutos também foi bastante variável entre os genótipos, apresentando entre 89 e 132 g, e a maioria dos genótipos apresentou frutos maiores que a cultivar de verão. As colorações rosa, vermelho, amarelo e verde da casca dos frutos foram as mais evidentes, e a forma principal dos frutos foi determinada como redonda, cônica e oblata entre os genótipos. ART08-9, ART08-4, ART08-21 e ART08-22apresentaram frutos maiores distintos, e ART08-1, ART08-2, ART08-5, ART08-12 e ART08-17 apresentaram maior conteúdo fenólico total e capacidade antioxidante. Os resultados do estudo mostraram diferenças significativas para a maioria das características morfológicas, sensoriais e bioquímicas. Assim, essas características dos genótipos da maçã cultivadas no verão foram distintos, e esses resultados podem ser atribuídos a diferenças no contexto genético dos genótipos.

Assessment of physical, microstructural, thermal, techno-functional and rheological characteristics of apple (Malus domestica) seeds of Northern Himalayas.

In this research, two common apple seed cultivars Viz: 'Golden Delicious' (GD) and 'Red Delicious' (RD) of Northern Himalayan region were characterized for physical, techno-functional, microstructure, thermal, and rheological properties. Seeds showed a significant difference in width, arithmetic, and geometric mean diameters, volume, and surface area. Proximate analysis results revealed that seed flours have high oil content (> 20%) and are potentially rich sources of protein (> 40%). Color analysis of flours indicated their satisfactory whiter color with higher brightness values (L* ˃ 75), resulting from the reduced particle size which allows greater light penetration and relatively lower a* (< 1.5) and b* (< 11) values. Techno-functional attributes including water/oil absorption capacity, emulsifying capacity, and emulsion stability were significantly higher in RD than GD flour. There was also a significant difference in the average particle size of seed flours. Flour micrographs indicated the presence of oval/spherical-shaped starch granules embedded in dense protein matrix while, Differential Scanning calorimeter (DSC) revealed exothermic transition enthalpies for seed flours. Additionally, seed flours depicted high elastic modulus (G'), suggesting their suitability for modifying food texture. It was concluded that apple seeds exhibit significant potential for use in formulating protein-enriched foods while contributing to reducing industrial wastage.

Phenotypic variation of floral organs in flowering crabapples and its taxonomic significance.

BACKGROUND: In angiosperms, phenotypic variation of floral organs is often considered as the traditional basis for the evolutionary relationship of different taxonomic groups above the species level. However, little is known about that at or below the species level. Here, we experimentally tested the phenotypic variation of Malus floral organs using combined methods of intraspecific uniformity test, interspecific distinctness analysis, principal component analysis, Pearson correlation analysis, and Q-type cluster analysis. The ancestor-inclined distribution characteristic analysis of Malus species and cultivars floral attributes was also carried out, so as to explore its taxonomic significance. RESULTS: 15/44 phenotypic traits (e.g., flower shape, flower type, flower diameter, ...) were highly consistent, distinguishable, and independent and could be used as the basis for Malus germplasm taxonomy. The studied 142 taxa were divided into two groups (A, B) and five sub-groups (A1, A2, B1, B2, B3), with significantly variable floral phenotypic attributes between groups and within sub-groups. Malus natural species were relatively clustered in the same section (series) while homologous cultivars showed evidence of ancestor-inclined distribution characteristics. However, no significant correlation between the evolutionary order of sections (Sect. Docyniopsis → Sect. Chloromeles → Sect. Sorbomalus → Sect. Eumalus) and group/sub-groups (B3 → B2 → B1 → A). CONCLUSIONS: Phenotypic variation of floral organs could better explore the genetic relationship between Malus taxa. The findings improved our cognition of floral phenotypic variation taxonomic significance under the species level.

Spatial and temporal evolution of quantitative magnetic resonance imaging parameters of peach and apple fruit - relationship with biophysical and metabolic traits.

Fruits are complex organs that are spatially regulated during development. Limited phenotyping capacity at cell and tissue levels is one of the main obstacles to our understanding of the coordinated regulation of the processes involved in fruit growth and quality. In this study, the spatial evolution of biophysical and metabolic traits of peach and apple fruit was investigated during fruit development. In parallel, the multi-exponential relaxation times and apparent microporosity were assessed by quantitative magnetic resonance imaging (MRI). The aim was to identify the possible relationships between MRI parameters and variations in the structure and composition of fruit tissues during development so that transverse relaxation could be proposed as a biomarker for the assessment of the structural and functional evolution of fruit tissues during growth. The study provides species-specific data on developmental and spatial variations in density, cell number and size distribution, insoluble and soluble compound accumulation and osmotic and water potential in the fruit mesocarp. Magnetic resonance imaging was able to capture tissue evolution and the development of pericarp heterogeneity by accessing information on cell expansion, water status and distribution at cell level, and microporosity. Changes in vacuole-related transverse relaxation rates were mostly explained by cell/vacuole size. The impact of cell solute composition, microporosity and membrane permeability on relaxation times is also discussed. The results demonstrate the usefulness of MRI as a tool to phenotype fruits and to access important physiological data during development, including information on spatial variability.

Exogenous 6-benzyladenine application affects root morphology by altering hormone status and gene expression of developing lateral roots in Malus hupehensis.

Malus hupehensis is an extensively used apple rootstock in China. In the current study, M. hupehensis seedlings were treated with exogenous 2.2 µm 6-benzyladenine (6-BA) so as to investigate the mechanism by which 6-BA affects lateral root development. The results indicate that 6-BA treatment promotes elongation and thickening of both root and shoot in M. hupehensis, but reduces the number of lateral roots, as well as reducing the auxin level after 6-BA treatment. Moreover, MhAHK4, MhRR1 and MhRR2 were also significantly up-regulated in response to 6-BA treatment. Expression levels of auxin synthesis- and transport-related genes, such as MhYUCCA6, MhYUCCA10, MhPIN1 and MhPIN2, were down-regulated, which corresponds with lower auxin levels in the 6-BA-treated seedlings. A negative regulator of auxin, MhIAA3, was induced by 6-BA treatment, leading to reduced expression of MhARF7 and MhARF19 in 6-BA-treated seedlings. As a result, expression of MhWOX11, MhWOX5, MhLBD16 and MhLBD29 was blocked, which in turn inhibited lateral root initiation. In addition, a lower auxin level decreased expression of MhRR7 and MhRR15, which repressed expression of key transcription factors associated with root development, thus inhibiting lateral root development. In contrast, 6-BA treatment promoted secondary growth (thickening) of the root by inducing expression of MhCYCD3;1 and MhCYCD3;2. Collectively, the changes in hormone levels and gene expression resulted in a reduced number of lateral roots and thicker roots in 6-BA-treated plants.

Wetting and adhesion behavior on apple tree leaf surface by adding different surfactants.

OBJECTIVE: This study was conducted to investigate the wetting behavior of different surfactant solutions on the leaf surfaces of apple during the fruit formation stage. METHODS: Five surfactants, including C12E5, Tween-20, Triton X-100, DTAB, and SDS were evaluated in this study. The contact angle, surface tension, adhesion tension, work of adhesion, and solid-liquid interface tension of droplets on the leaf surface were determined by the drop method. RESULTS: The results showed that the nonionic surfactants C12E5 and Triton X-100 had better wetting effects than other surfactants. Moreover, when the concentration of C12E5 and Triton X-100 was 1 × 10-3 mol/L, the leaves reached a completely wet state. Toxicity measurement showed that the incubation rate of Carposina niponensis eggs decreased gradually with increasing content of C12E5 or Triton X-100. Additionally, field efficacy analysis showed that adding C12E5 or Triton X-100 significantly improved the beta-cyfluthrin 3% water emulsion (EW) against C. niponensis. CONCLUSIONS: These results indicate that the surfactants C12E5 and Triton X-100 can significantly improve pesticide application, which will be helpful for reducing pesticide use and developing new pesticides.

Phenotypic variation of floral organs in Malus using frequency distribution functions.

BACKGROUND: Phenotypic diversity of floral organs plays an important role in plant systematic taxonomy and genetic variation studies. Previous research have focused on the direction of variation but disregarded its degree. Phenotypic variation (including directions and degrees) of 17 floral traits from wild to cultivated crabapples were explored by comparing their distributions and deviations in three different dimensions: floral organ number, size, and the shape. RESULTS: Except for petal number, petal length / petal width, and sepal length / sepal width, the analyzed floral traits of cultivated crabapples all showed downward distributed box bodies in box plot analysis and left deviations of fitted curves in frequency distribution function analysis when compared to the wild, which revealed consistent variation directions of petaloid conversion (pistils or stamens → petals), size miniaturization (large → small), and shape narrowness (petal shape: circular → elliptic; sepal shape: triangular → lanceolate). However, only seven floral traits exhibited significant differences in box plot analysis, while all of the traits in frequency distribution function analysis were obviously offset. The variation degrees were quantitatively characterized by sizing traits > shaping traits > numbering traits and by horizontal dimensions > radial dimensions. CONCLUSIONS: Frequency distribution function analysis was more sensitive than the box plot analysis, which constructed a theoretical basis for Malus flower type breeding and would provide a new quantitative method for future evaluation of floral variation among different groups of angiosperms at large.

Effects of nitrate deficiency on nitrate assimilation and chlorophyll synthesis of detached apple leaves.

Nitrogen is one of the most important nutrients for plant growth and development. Nitrate nitrogen (NO3--N) is the main form of nitrogen taken up by plants. Understanding the effects of exogenous NO3--N on nitrogen metabolism at the gene expression and enzyme activity levels during nitrogen assimilation and chlorophyll synthesis is important for increasing nitrogen utilization efficiency. In this study, cell morphology, NO3--N uptake rates, the expression of key genes related to nitrogen assimilation and chlorophyll synthesis and enzyme activity in apple leaves under NO3--N deficiency were investigated. The results showed that the cell morphology of apple leaves was irreversibly deformed due to NO3--N deficiency. NO3--N was absorbed slightly one day after NO3--N deficiency treatment and effluxed after 3 days. The relative expression of genes encoding nitrogen assimilation enzymes and the activity of such enzymes decreased significantly after 1 day of NO3--N deficiency treatment. After treatment for 14 days, gene expression was upregulated, enzyme activity was increased, and NO3--N content was increased. NO3--N deficiency hindered the transformation of 5-aminobilinic acid (ALA) to porphobilinogen (PBG), suggesting a possible route by which NO3--N levels affect chlorophyll synthesis. Collectively, the results indicate that NO3--N deficiency affects enzyme activity by altering the expression of key genes in the nitrogen assimilation pathway, thereby suppressing NO3--N absorption and assimilation. NO3--N deficiency inhibits the synthesis of the chlorophyll precursor PBG, thereby hindering chlorophyll synthesis.

Phenolic distribution in apple epidermal and outer cortex tissue by multispectral deep-UV autofluorescence cryo-imaging.

Phenolic compounds in fruit are involved in responses to biotic and abiotic stresses and are responsible for organoleptic properties. To establish the distribution of these secondary metabolites at the tissue and sub-cellular scales, mapping of fluorescence in apple epidermis and outer cortex tissue in cryogenic condition was performed after deep-UV excitation at 275 nm. Douce Moën and Guillevic cider apple varieties were sampled and frozen after harvest, after 30 days at 4 °C and after 20 days at room temperature. Image analysis of fluorescence emission images acquired between 300 and 650 nm allowed the assignment of fluorescence signals to phenolic compound families based on reference molecules. Emission attributed to monomeric and/or condensed flavanol was localized in whole tissue with major fluorescence in the cuticle region. Hydroxycinnamic acids were found predominantly in the outer cortex and appeared in the cell wall. Fluorescent pigments were mostly found in the epidermis. The distribution of flavanols in the sub-cuticle and phenolic acids in the outer cortex distinguished apple varieties. Storage conditions had no impact on phenolic distribution. The proposed fluorescent imaging and analysis approach enables studies on phenolic distribution in relation to fruit development, biotic/abiotic stress resistance and quality.

Automatic Parameter Tuning for Adaptive Thresholding in Fruit Detection.

This paper presents an automatic parameter tuning procedure specially developed for a dynamic adaptive thresholding algorithm for fruit detection. One of the major algorithm strengths is its high detection performances using a small set of training images. The algorithm enables robust detection in highly-variable lighting conditions. The image is dynamically split into variably-sized regions, where each region has approximately homogeneous lighting conditions. Nine thresholds were selected to accommodate three different illumination levels for three different dimensions in four color spaces: RGB, HSI, LAB, and NDI. Each color space uses a different method to represent a pixel in an image: RGB (Red, Green, Blue), HSI (Hue, Saturation, Intensity), LAB (Lightness, Green to Red and Blue to Yellow) and NDI (Normalized Difference Index, which represents the normal difference between the RGB color dimensions). The thresholds were selected by quantifying the required relation between the true positive rate and false positive rate. A tuning process was developed to determine the best fit values of the algorithm parameters to enable easy adaption to different kinds of fruits (shapes, colors) and environments (illumination conditions). Extensive analyses were conducted on three different databases acquired in natural growing conditions: red apples (nine images with 113 apples), green grape clusters (129 images with 1078 grape clusters), and yellow peppers (30 images with 73 peppers). These databases are provided as part of this paper for future developments. The algorithm was evaluated using cross-validation with 70% images for training and 30% images for testing. The algorithm successfully detected apples and peppers in variable lighting conditions resulting with an F-score of 93.17% and 99.31% respectively. Results show the importance of the tuning process for the generalization of the algorithm to different kinds of fruits and environments. In addition, this research revealed the importance of evaluating different color spaces since for each kind of fruit, a different color space might be superior over the others. The LAB color space is most robust to noise. The algorithm is robust to changes in the threshold learned by the training process and to noise effects in images.

Russeting partially restores apple skin permeability to water vapour.

MAIN CONCLUSION: The higher water loss of russeted fruit results from the higher permeance of the periderm of the russeted skin as compared to that of the intact cuticle and epidermis. Apple fruit surfaces are often in-parallel composites, comprising areas of intact cuticle (atop a healthy epidermis) adjacent to areas covered by periderm (so-called russet). The occurrence of non-russeting and russeting genotypes makes this species an ideal model to study the barrier properties of its composite skin. The objective was to quantify the water vapour permeances of non-russeted ([Formula: see text]) and russeted fruit skins ([Formula: see text]). Rates of water loss from whole fruit ([Formula: see text]) and excised epidermal skin segments (ES) or peridermal skin segments (PS) were quantified gravimetrically. The [Formula: see text] was larger in russeting than in non-russeting genotypes because [Formula: see text] exceeded [Formula: see text] by about twofold. Also, the [Formula: see text] of russeting genotypes was larger than that of non-russeting genotypes. Generally, [Formula: see text] was more variable than [Formula: see text]. These differences were consistent across seasons and genotypes. The lower [Formula: see text] as compared to [Formula: see text] resulted primarily from the higher wax content of the cuticle of the [Formula: see text]. For non-russeted genotypes, the value of [Formula: see text] was significantly related to the permeance determined on the same intact fruit ([Formula: see text]). Close relationships were also found between the [Formula: see text] calculated from [Formula: see text] determined on the same fruit and the measured [Formula: see text]. For russeting genotypes, the [Formula: see text] or [Formula: see text] were not correlated with [Formula: see text]. The [Formula: see text] calculated from [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] (all determined on an individual-fruit basis) was significantly correlated with the measured [Formula: see text]. Our results demonstrate that the periderm permeance exceeds the cuticle permeance and that permeances of non-russeted surfaces of russeting genotypes exceed those of non-russeting genotypes.

Can you make morphometrics work when you know the right answer? Pick and mix approaches for apple identification.

Morphological classification of living things has challenged science for several centuries and has led to a wide range of objective morphometric approaches in data gathering and analysis. In this paper we explore those methods using apple cultivars, a model biological system in which discrete groups are pre-defined but in which there is a high level of overall morphological similarity. The effectiveness of morphometric techniques in discovering the groups is evaluated using statistical learning tools. No one technique proved optimal in classification on every occasion, linear morphometric techniques slightly out-performing geometric (72.6% accuracy on test set versus 66.7%). The combined use of these techniques with post-hoc knowledge of their individual successes with particular cultivars achieves a notably higher classification accuracy (77.8%). From this we conclude that even with pre-determined discrete categories, a range of approaches is needed where those categories are intrinsically similar to each other, and we raise the question of whether in studies where potentially continuous natural variation is being categorised the level of match between categories is routinely set too high.

Biophotonic approach for the characterization of initial bitter-rot progression on apple specimens using optical coherence tomography assessments.

The tremendous advances achieved in the biophotonics technologies have intensified the necessity for non-invasive modalities that can characterize diverse biological materials with increased sensitivity and resolution. Optical coherence tomography (OCT) is one of the techniques that has been applied for biological applications in medicine and agriculture to identify structural properties. Herein, we report the successful incorporation of OCT for the identification of morphological changes that occur as a result of the bitter rot disease, through continuous detection of structural changes. Detailed inner morphological structural changes occurring in fruit specimens were precisely analyzed as a function of the disease incubation period using OCT. The conducted histological correlation and quantitative three-dimensional evaluations provide a robust platform for further discoveries related to plant materials. The results highlight the initial identification of bitter rot progression on apple specimens owing to the non-invasive inspection capability of OCT. Therefore, we expect that the proposed method will enable immediate sensitivity improvements in the inspection of plant diseases for postharvest utility.

Genome-wide identification of genes involved in polyamine biosynthesis and the role of exogenous polyamines in Malus hupehensis Rehd. under alkaline stress.

Polyamines (PAs) in plants are growth substrates with functions similar to phytohormones. Although they contribute to diverse processes, little is known about their role in stress responses, especially for perennial woody plants. We conducted a genome-wide investigation of 18 sequences involved in PA biosynthesis in the genome of apple (Malus domestica). Further analysis was performed to construct a phylogenetic tree, analyze their protein motifs and gene structures. In addition, we developed their expression profiles in response to stressed conditions. Both MDP0000171041 (MdSAMDC1) and MDP0000198590 (MdSPDS1) were induced by alkaline, salt, ABA, cold, and dehydration stress treatments, suggesting that these genes are the main contributors to activities of S-adenosylmethionine decarboxylase (EC 4.1.1.50) and spermidine synthase (EC 2.5.1.16) in apple. Changes in PA biosynthesis under stress conditions indicated that spermidine and spermine are more essential than putrescine for apple, especially when responding to alkaline or salt stress. When seedlings of M. hupehensis Rehd. were supplied with exogenous PAs, their leaves showed less chlorosis under alkaline stress when compared with untreated plants. This application also inhibited the decline in SPAD levels and reduced relative electrolyte leakage in those stressed seedlings, while increasing their concentration of active iron. These results suggest that the alteration in PA biosynthesis confers enhanced tolerance to alkaline stress in M. hupehensis Rehd.

The effect of polyploidization on tree hydraulic functioning.

PREMISE OF THE STUDY: Recent research has highlighted the importance of living tissue in wood. Polyploidization can impact amounts and arrangements of living cells in wood, potentially leading to increased drought tolerance. Tetraploid variants were created from the apple cultivar Malus ×domestica 'Gala' (Gala-4x), and their vulnerability to drought-induced cavitation and their hydraulic capacitance were compared to those of their diploid predecessors (Gala-2x). Assuming a positive correlation between polyploidy and drought tolerance, we hypothesized lower vulnerability and higher capacitance for the tetraploid. METHODS: Vulnerability to drought-induced cavitation and the hydraulic capacitance were quantified through acoustic emission and continuous weighing of shoots during a bench-top dehydration experiment. To underpin the hydraulic trait results, anatomical variables such as vessel area, conduit diameter, cell wall reinforcement, and ray and vessel-associated parenchyma were measured. KEY RESULTS: Vulnerability to drought-induced cavitation was intrinsically equal for both ploidy variants, but Gala-4x proved to be more vulnerable than Gala-2x during the early phase of desiccation as was indicated by its significantly lower air entry value. Higher change in water content of the leafy shoot, higher amount of parenchyma, and larger vessel area and size resulted in a significantly higher hydraulic capacitance and efficiency for Gala-4x compared to Gala-2x. CONCLUSIONS: Both ploidy variants were typified as highly sensitive to drought-induced cavitation, with no significant difference in their overall drought vulnerability. But, when water deficit is short and moderate, Gala-4x may delay a drought-induced decrease in performance by trading hydraulic safety for increased release of capacitively stored water from living tissue.

MdWRKY9 overexpression confers intensive dwarfing in the M26 rootstock of apple by directly inhibiting brassinosteroid synthetase MdDWF4 expression.

Dwarfing rootstocks enable high-density planting and are therefore highly desirable in modern apple (Malus domestica) production. M26 is a semi-dwarfing rootstock that is used worldwide, but identifying intensive dwarfing rootstock is a major goal of apple breeding programs. Herein, we show that MdWRKY9 mediates dwarfing by directly inhibiting the transcription of the brassinosteroid (BR) rate-limiting synthetase MdDWF4 and reducing BR production. We found that the transcriptional factor MdWRKY9 is highly expressed in all tested dwarfing rootstocks. Transgenic lines of M26 rootstock overexpressing MdWRKY9 exhibit further dwarfing, which resulted from the reduced BR levels and was reversed via exogenous brassinolide treatment. Both an in vivo chromatin immunoprecipitation (ChIP) analysis and an in vitro electrophoretic mobility shift assay (EMSA) indicated that MdWRKY9 binds to the promoter of MdDWF4. Furthermore, MdWRKY9 repressed MdDWF4 expression in stable transgenic apple plants as determined by quantitative PCR. In addition, RNA-interfered expression of MdWRKY9 in transiently transformed apple calli led to a significant increase of MdDWF4, suggesting MdWRKY9 plays a critical role in regulating the expression of MdDWF4. We report a novel dwarfing mechanism in perennial woody plants that involves WRKY-controlled BR production, and present a new dwarfing M26 rootstock for potential applications in apple production.

Realistic texture synthesis for point-based fruitage phenotype.

Although current 3D scanner technology can acquire textural images from a point model, visible seams in the image, inconvenient data acquisition and occupancy of a large space during use are points of concern for outdoor fruit models. In this paper, an SPSDW (simplification and perception based subdivision followed by down-sampling weighted average) method is proposed to balance memory usage and texture synthesis quality using a crop fruit, such as apples, as a research subject for a point-based fruit model. First, the quadtree method is improved to make splitting more efficient, and a reasonable texton descriptor is defined to promote query efficiency. Then, the color perception feature is extracted from the image for all pixels. Next, an advanced sub-division scheme and down-sampling strategy are designed to optimize memory space. Finally, a weighted oversampling method is proposed for high-quality texture mixing. This experiment demonstrates that the SPSDW method preserves the mixed texture more realistically and smoothly and preserves color memory up to 94%, 84.7% and 85.7% better than the two-dimesional processing, truncating scalar quantitative and color vision model methods, respectively.

Design of a simple non-destructive detection system using P-wave lasers for determining the soluble solids content of apples.

The simple and nondestructive detection system studied in this work uses a near-infrared (NIR) detector and parallel-polarized (P-wave) NIR lasers to determine the soluble solids content (SSC) of apples. The P-wave NIR laser in this system is incident into the apple's pulp at the Brewster angle to minimize the interference caused by interfacial reflections. After the apple has been illuminated by four P-wave NIR lasers that correspond to the specified wavelengths of the SSC chemical bonds (880, 940, 980, and 1064 nm), the prediction of correlation (rp2) and the root-mean-square error for prediction (RMSEP) of the SSC are determined via partial least square regression analysis of the reflectance. Our results indicate that the use of P-wave lasers at the Brewster angle (as the angle of incidence) and the above specified wavelengths for the prediction set measurement of the SSC of apples obtained an rp2 of 0.88 and an RMSEP of 0.47°Brix. These rp2 are 6% higher, and the RMSEPs are 9% lower, than those obtained using non-polarized lasers.

Temperature heterogeneity over leaf surfaces: the contribution of the lamina microtopography.

Temperature is spatially heterogeneous over leaf surfaces, yet the underlying mechanisms are not fully resolved. We hypothesized that the 3D leaf microtopography determines locally the amount of incoming irradiation flux at leaf surface, thereby driving the temperature gradient over the leaf surface. This hypothesis was tested by developing a model of leaf temperature heterogeneity that includes the development of the leaf boundary layer, the microtopography of the leaf surface and the physiological response of the leaf. Temperature distributions under various irradiation loads (1) over apple leaves based on their 3D microtopography, (2) over simulated flat (2D) apple leaves and (3) over 3D leaves with a transpiration rate distributed as in 2D leaves were simulated. Accuracy of the predictions was quantified by comparing model outputs and thermographic measurements of leaf surface temperature under controlled conditions. Only the model with 3D leaves predicted accurately the spatial heterogeneity of surface temperature over single leaves, whereas the mean temperature was well predicted by both 2D and 3D leaves. We suggest that in these conditions, the 3D leaf microtopography is the primary driver of leaf surface heterogeneity in temperature when the leaf is exposed to a light/heat source.