Postharvest noninvasive assessment of fresh chestnut (Castanea spp.) internal decay using computer tomography images

X-ray computed tomography (CT) is an effective noninvasive tool to visualize fresh agricultural commodities’ internal components and quality attributes, including those of chestnuts (Castanea spp). There is no procedure to automatically, effectively and efficiently classify fresh commodities from a continuous inline flow through a CT system. If the information obtained by CT scanning of fresh agricultural commodities is to be used in an industrial application (e.g. inline sorting), automated interpretation of CT images is essential. For this purpose, an image analysis method (algorithm) for the automatic classification of CT images obtained from 2848 fresh chestnuts (cv. ‘Colossal’ and ‘Chinese seedlings’), during the harvesting years from 2009 to 2012, was developed and tested. Classification accuracy was evaluated by comparing the classes obtained from six CT images per chestnut to their internal quality assessment. An experienced human rater performed internal quality assessment by visually and invasively rating fresh chestnut internal decay severity (quality) into 5-, 3- and 2-classes.After CT image preprocessing, cropping and segmentation, 1194 grayscale intensity and textural features were extracted from six resultant CT images per sample. Relevant features were selected using a sequential forward selection algorithm with the Fisher discriminant objective function. 86, 155 and 126 features were effective in designing a quadratic discriminant classifier with a 4-fold cross-validation with a performance accuracy of 85.9%, 91.2% and 96.1% for 5, 3 and 2 classes, respectively. This method is accurate and objective in determining fresh chestnut internal quality, and the methodology is applicable to automatic noninvasive inline CT sorting system development.     

Molecular analysis of softening and ethylene synthesis and signaling pathways in a non-softening apple cultivar, ‘Honeycrisp’ and a rapidly softening cultivar, ‘McIntosh’

A feature of ‘Honeycrisp’ apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] is that they maintain flesh firmness over extended storage. The objective of this study was to elucidate molecular mechanisms that are responsible for slow softening of ‘Honeycrisp’ as compared with a rapidly softening cultivar, ‘McIntosh’. Fruit from both cultivars were picked during the normal harvest period and stored at 20 °C for 10 d. Internal ethylene concentrations (IECs) in ‘Honeycrisp’ fruit were lower than in ‘McIntosh’, but at climacteric levels of ethylene ‘Honeycrisp’ fruit maintained their firmness over this period, while ‘McIntosh’ softened rapidly. Concentrations of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) were higher in ‘Honeycrisp’ than in ‘McIntosh’ apples. qRT-PCR analysis was carried out for genes involved in ethylene biosynthesis, perception and signaling [ACC synthase (MdACS); ACC oxidase (MdACO); ethylene receptors (MdETR and MdERS); constitutive triple response (MdCTR); ethylene response factor (MdERF)], as well as those involved in cell wall metabolism [polygalacturonase (MdPG); xyloglucan endotransglucosylase (MdXTH); expansin (MdEXP); β-galactosidase (Md β-GS); arabinofuranosidase (MdAFase); pectate lyase (MdPL)]. At comparable IECs, the expression of genes involved in ethylene synthesis, ethylene perception and signal transduction was generally much higher in ‘Honeycrisp’ than in ‘McIntosh’ fruit. However, the expression of MdAFase and MdEXP3 was generally lower in ‘Honeycrisp’ than in ‘McIntosh’, while that of MdPG and MdPL was extremely low in ‘Honeycrisp’. Expression of MdPG1 was very low, even though IECs were at climacteric levels. Absence of fruit softening in ‘Honeycrisp’ is probably associated with restricted cell wall enzyme activity. The lower maximum IECs found in ‘Honeycrisp’ compared with ‘McIntosh’ do not appear to be related to expression of genes involved in ethylene biosynthesis.     

Effects of gamma and electron beam irradiations on the triacylglycerol profile of fresh and stored Castanea sativa Miller samples

The present chestnut (Castanea sativa Miller) commercialization process, including distribution to novel markets, demands suitable preservation technologies. Irradiation has been considered a promising alternative to chemical fumigation (legally forbidden and harmful for human health and environment) or heat treatments (technological difficulties and low efficiency). Following previous studies on the effects of irradiation in different chemical parameters, the present work aimed to evaluate the effects of electron beam and γ-irradiation on the triacylglycerol profiles of fresh and stored chestnuts. An analysis of variance with type III sums of squares was performed using the general linear model procedure. As a classification technique, a linear discriminant analysis using the stepwise procedure was also applied. Independently of irradiation type, samples irradiated with higher doses showed higher modifications in triacylglycerol profiles. Samples irradiated with 1 and 3 kGy were clearly separated from the remaining groups in the linear discriminant analysis. The results highlight the potential of triacylglycerol profiles as indicators of chestnut irradiation. Irradiation might be recommended as a suitable method for chestnut preservation.     

Cold pre-treatment is effective for 1-MCP efficacy in ‘Tsugaru’ apple fruit

1-Methylcyclopropene (1-MCP) treatment maintains apple fruit quality during storage, but its efficacy is dependent on a number of conditions. ‘Tsugaru’ apples are a major early season cultivar in Japan, but because ‘Tsugaru’ fruit produce abundant ethylene, they have a short shelf-life, and efficacy of 1-MCP is not as high with ‘Tsugaru’ as with other cultivars. To improve 1-MCP efficacy, ‘Tsugaru’ fruit were pre-cooled at −1 °C or −3 °C for 24 h before 1-MCP treatment. Ethylene production decreased with the cold treatment, resulting in better storage after 1-MCP treatment. Although ethylene production was low at the end of 24 h of the cold pre-treatment, expression of ACS1, the ethylene receptor genes ERS1, ETR1(a), ETR1b, ETR2 and ETR5, and the cell wall degradation-related gene PG1 all increased with a 24 h cold treatment. It is assumed that these elevated gene expression levels were not caused by ethylene, but more directly by cold stimulus. Thus, a short period of cold stimulus suppresses ethylene production, but induces expression of some genes. 1-MCP treatment was more effective with some initial fruit chilling.     

云南甘薯地方主栽品种收集与脱毒复壮研究

为了更好地促进云南甘薯生产,收集云南地方主栽甘薯品种27个进行田间评价,并对其中的6个品种脱毒后进行田间对比试验。试验表明,有些品种产量较高,如‘普洱黄山芋’,产量达20.04 t/hm²,‘丘北白皮’亦达15.60 t/hm²;有些品种品质较好,如‘研和板栗薯’和‘华坪紫心’等;‘研和板栗薯’、‘建水灰薯’、‘华坪紫心’、‘马龙紫薯’、‘昆明紫薯’和‘建水紫薯’6个品种,脱毒后薯块平均增产幅度为175.8%;其中‘建水灰薯’脱毒后产量达24.00 t/hm²,比对照增产16.0 t/hm²,增幅为200.1%。通过脱毒,可以显著提高目前云南主栽甘薯品种的产量,更好为甘薯生产服务。     

Effects of controlled atmospheres and low temperature on storability of chestnuts manually and mechanically harvested

The aim of this study was to determine the effect of controlled atmospheres on quality of manually and mechanically harvested chestnuts (Castanea sativa Miller cv. Marrone Fiorentino), treated with “water curing” and stored for two months. Parameters such as color, weight, firmness, acetaldehyde and ethanol concentration, soluble solids content and sensory quality were analyzed. Mechanical harvesting increased the incidence of cracks and bruises inflicted on the chestnuts, as well as removal of the tuft. As regards storability, controlled atmospheres helped maintain chestnut quality, preserving typical organoleptic characteristics and reducing the incidence of rots where damage caused by cracks and removal of the tuft were most frequent from use of a mechanical harvester.     

Heat tolerance for yield and its components in different wheat cultivars

Summary Twenty one diverse, standard and experimental cultivars of common spring wheat (Triticum aestivum L.) were tested for the effect of heat stress on phenology, yield and its components by growing the materials for 2 years under full irrigation during the hot summer (offseason), and the cool winter (normal) conditions. Heat tolerance was estimated for each variable by the heat susceptibility index (S) which scales the reduction in cultivar performance from cool to hot conditions relative to the respective mean reduction over all cultivars.Genotypes differed significantly in S for yield and its components. The ranking of cultivars in S over the 2 years was consistent for yield, kernels per spike and kernel weight, but not for spike number. Of the three yield components, the greatest genotypic variation in S was expressed for kernels per spike. However, S for yield could not be simply attributed to S in a unique component across all cultivars. On the other hand, a general linear model regression of summer yield on its components revealed that the most important yield component affecting yield variation among cultivars under heat stress was kernel number per spike. Kernel number per spike was positively associated across cultivars with longer duration and greater stabilty of thermal time requirement from emergence to double ridge. It is therefore concluded that kernel number per spike under heat stress is a reasonable estimate of heat tolerance in yield of wheat and that this tolerance is operative already during the first 2 to 3 weeks of growth.     

Location of genes controlling some characters in the spring wheat variety zlatka by monosomic analysis

Summary Using Chinese Spring monosomics an analysis was made to locate the genes controlling kernel colour, kernel groove shape, and the shape of the upper margin of the glume in the spring wheat Zlatka. Two genes controlling kernel colour, R₁ and R₃, which had been described in a number of varieties, were found on chromosomes 3D and 3B of Zlatka, respectively.In Zlatka sharp margin of kernel groove was dominant over rounded margin. The dominant genes were located on chromosomes 3A and 5A.Chinese Spring has a sloping upper glume margin, which was found to be dominant over horizontal glume margin in Zlatka. This character is governed by three complementary genes. Recessive alleles of the genes, described as g₁, g₂, g₃, were located on chromosomes 5A, 5B and 5D respectively.     

Effect of penetration speed on flesh firmness measured on stored kiwifruit

The effect of penetration speed on flesh firmness (FF) measurement by motorised penetrometer was examined for ‘Hayward’ (Actinidia deliciosa var. deliciosa) and ‘Hort16A’ (Actinidia chinensis Planch. var. chinensis) kiwifruit. Data was collected for penetration speeds varying from 4 to 40 mm s⁻¹ using stored fruit of FF ∼10 N; a typical minimum FF threshold for export from New Zealand. Measurements were made on a number of instruments (Instron, GUSS FTA, HortPlus, TA.XTplus), using fruit from different orchards and in each of two different seasons. As expected, FF values increased with increasing penetration speed. A firmness-speed model was developed, based on the Maxwell rheological model for viscoelastic materials, which proved adequate in describing the FF data in terms of the effect of penetration speed. The effect of penetration speed was not adversely influenced by cultivar, season or instrument type. Within the range of fruit firmness examined - stored fruit below 20 N - it was concluded that the firmness-speed model could be successfully used to compare firmness values generated using instruments operating at different penetration speeds.     

Effects of ethylene, pollination, and ethylene inhibitor treatments on flower senescence of gentians

Flower senescence of the potted gentian (Gentiana scabra) ‘Shinbisei’ was investigated in relation to ethylene sensitivity and production. ‘Shinbisei’ flowers were used for all experiments except for those with inflorescences. Exposure to ethylene at 0.5 μL L⁻¹ or higher concentrations for 24 h markedly accelerated flower senescence, indicating that G. scabra flowers are highly sensitive to ethylene. Treatment with 0.2 or 0.5 mM silver thiosulfate complex (STS) and 2 μL L⁻¹ 1-methylcyclopropene (1-MCP), ethylene action inhibitors, and 50 mM α-aminoisobutyric acid, an inhibitor of 1-aminocyclopropane-1-carboxylate (ACC) oxidase, did not delay flower senescence. However, treatment with 1 mM l-α-(2-aminoethoxyvinyl) glycine, an inhibitor of ACC synthase, slightly delayed flower senescence. Pollination significantly accelerated petal senescence of G. scabra flowers. Ethylene production of petals, gynoecium, and stamens in unpollinated flowers slightly increased during senescence. Pollination significantly increased ethylene production of petals, gynoecium and stamens 1 day after pollination. To clarify whether 1-MCP delays senescence of cut gentian inflorescences, cut G. scabra ‘Yuki-hotaru’, G. scabra × Gentiana triflora ‘Aoi-kaze’, and G. triflora ‘Koharu’ inflorescences with various stages of flowers, including buds with colored petals, were treated with 2 μL L⁻¹ 1-MCP for 24 h. 1-MCP treatment delayed flower wilting of cut inflorescences of ‘Aoi-kaze’ and ‘Yuki-hotaru’ more than that of ‘Koharu’, suggesting that there is species variation in the effect of 1-MCP in delaying flower senescence of cut gentian inflorescences.     

Rating cultivars and trials in applied plant breeding

Summary The number of means m, from which a particular cultivar differs significantly, is used to arrange cultivars in order of descending superiority. For n cultivars under study, the maximum m value corresponding to the best cultivar is n-1, indicating that it exceeds significantly the n-1 other cultivars, and the minimum zero. Because m represents an objective and reliable statistical measure of cultivar performance, it has been used to calculate two indexes: (1) performance index, P=100 m/(n-1), giving the percentage of means which a particular cultivar exceeds significantly, and (2) differentiation index, D=200 m/n (n-1), giving the percentage of paired comparisons between cultivars that show significant differences. Rating cultivars according to P across years (Py), sites (Ps), and years plus sites (Pys), gives an overall picture of the relative superiority of the entries. Rating trials according to D allows comparisons between trials and offers the possibility when the same sets of entries are compared each year across sites, to identify sites that give maximum differentiation.     

A preliminary study on the effect of metabolic stress disinfection and disinfestation (MSDD) on ripening physiology and quality of kiwifruit and apple

Metabolic stress disinfection and disinfestation (MSDD) is a relatively new quarantine treatment in which fruit are exposed to rapid decompression and compression cycles and high CO₂ atmosphere, followed by exposure to ethanol vapour under decompression. This study evaluated the ripening response of ‘Hayward’ kiwifruit (Actinidia deliciosa) and ‘Pink Lady’ apple (Malus x domestica) to MSDD treatment, which can control longtailed mealybug (Pseudococcus longispinus). Following the treatments, fruit were held at 20 °C for 7 d for shelf-life assessment, while the remainder were refrigerated at 0.5 °C for 16 weeks. Respiration rate, volatile (ethylene, ethanol and acetaldehyde) production rates, firmness and disorders were measured at regular time intervals. MSDD treatments did not affect the metabolic activities and quality of ‘Pink Lady’ apples. However, firmness was reduced by 4.9 N in non-refrigerated MSDD treated fruit. MSDD treatments did not control superficial scald disorder in refrigerated ‘Pink Lady’ apples. For ‘Hayward’ kiwifruit, treatments increased the respiration rate and ethylene production of short-term refrigerated fruit, promoted endogenous production of ethanol and acetaldehyde in both short-term and long-term refrigerated fruit. MSDD treatments also increased the incidence of rots in refrigerated ‘Hayward’ kiwifruit. MSDD treatments accelerated the softening of short-term refrigerated kiwifruit, but retarded the softening of ‘Hayward’ kiwifruit during the 16 weeks of refrigerated storage. MSDD could potentially be used as a quarantine treatment of apples. Further studies are required on the sensory effect of MSDD treatment.     

不同品种烤烟鲜叶表面提取物主要成分比较

为研究贵州主栽烟草品种的品质特征,开发生产特色优质烟服务。2009年选取4个贵州省主栽烟草品种为对象,研究其叶表面提取物特征。所用品种包括‘云烟85’、‘K326’、‘贵烟201’和‘南江3号’,每个品种均分下中上3个部位采取成熟鲜叶,用二氯甲烷提取叶表面物质进行分析检测。结果表明：烤烟（Nicotiana Tabacum）叶表面提取物主要包括烟碱、新植二烯、腺毛分泌物和烷烃类。不同品种叶表面提取物主要成分含量存在一定差异。四个品种叶表面提取物总量、新植二烯含量和腺毛分泌物含量的排序为‘南江3号’＜‘K326’＜‘贵烟201’＜‘云烟85’,烷烃物质平均含量排序为‘南江3号’＜‘云烟85’＜‘贵烟201’＜‘K326’。各品种烟叶腺毛分泌物中松香油平均含量与其它萜烯类物质总量相当,西柏三烯二醇含量大于西柏三烯一醇含量,α-西柏三烯二醇平均含量是β-西柏三烯二醇含量的2倍以上。各品种烷烃物质含量均以中部叶含量最低,其原因有待进一步研究分析。     

Interrelationships of allozymes and ribosomal DNA alleles in wild barley

Summary A genetic resources preservation program led to an in vitro germplasm collection of yam (Dioscorea spp.), obtained by nodal cutting and maintained under slow growth conditions with ((Knop, 1865) in George & Sherrington, 1984) modified medium. The collection comprises accessions of 14 species from Africa and Asia, including edible varieties from the humid intertropical areas, viz 10 wild species (D. abyssinica, D. bulbifera, D. burkilliana, D. dumetorum, D. hirtiflora, D. mangenotiana, D. minutiflora, D. praehensilis, D. schimperana, D. togoensis), 5 edible species (D. alata, D. bulbifera, D. cayenensis-D. rotundata complex, D. dumetorum and D. esculenta) and 1 interspecific hybrid (D. cayenensis-D. rotundata complex, cv. Krengle x D. praehensilis). Three factors that may influence the success in transfer from the in vivo to the in vitro conditions have been studied. These are: the type of introducted material (nodal cutting fragments, seeds and exchanged microplants), the introduction date and the genotype. Some significant differences in success were due to the type of introduced material, whereas the introduction date had no effect. On the other hand, some species showed a greater success in the transfer from the in vivo to the in vitro conditions than others. The three tuberization types (basal tuberization, aerial tuberization and boulage (tuberization without vegetative development) phenomena), according to species, are discussed.     

机械化种植对木薯产量和土壤肥力的影响研究

为探讨机械化种植对木薯产量和土壤肥力的影响,以‘新选048’、‘华南5号’和‘华南205’3个已在生产上大面积推广应用的木薯品种为材料,分别采用机械化种植与人工种植2种不同种植方式,对木薯产量及土壤肥力状况进行研究。结果表明：与人工种植相比,机械化种植土壤速效氮、速效磷、速效钾、有机质含量及木薯产量均明显增加,其中‘新选048’土壤速效N、P、K及有机质含量分别增加了7.23%、6.27%、16.76%、4.46%,‘华南5号’分别增加了11.09%、32.58%、21.80%、3.73%,‘华南205’分别增加了9.21%、14.28%、16.80%、5.21%;‘新选048’、‘华南5号’和‘华南205’3个木薯品种块根产量分别增加了14.02%、5.86%和16.70%。可见,机械化种植对改善土壤肥力,促进木薯生长发育,提高木薯产量起到积极的作用,应该在木薯生产中推广应用。在木薯机械生产种植上,‘新选048’和‘华南205’这2个木薯品种增产效果很明显,是值得广泛推广的品种。     

Inheritance of tolerance of the tomato (Lycopersicon esculentum Mill.) to metribuzin herbicide

Summary The inheritance of tolerance in the tomato (Lycopersicon esculentum Mill.) to metribuzin 4-amino-6-tert- butyl-3-(methylthio)-as-triazine-5(4H)-one herbicide was investigated. A biossay using a nutrient solution culture in controlled environment growth cabinets was used to evaluate progeny from tolerant by susceptible tomato cultivar crosses for response to metribuzin. Fireball and Vision were used as tolerant cultivars and Heinz 1706 as a susceptible cultivar. Parental, F₁, F₂, and some backcross generations were studied. Visual phytotoxicity, seedling height, and seedling dry weight were recorded.The bioassay was effective for classification of the segregating generations. F₂, and progeny variance analysis suggested that the inheritance of tolerance to metribuzin was controlled by one major gene with modifiers. Heritability values of 0.58 to 0.72 indicated a potential for cultivar improvement through plant breeding.     

不同贮藏方式对木薯种茎发芽及其相关生理特性影响研究

为了探讨不同贮藏方式对木薯种茎发芽及其相关生理特性的影响,以‘新选048’和‘桂热3号’木薯品种为材料,采用露地堆放和室内堆放2种不同贮藏方式对种茎进行处理,观察测定种茎发芽情况、生理生化特性、幼苗茎叶生长情况等。结果表明,露地堆放贮藏种茎发芽较快、发芽整齐、发芽率较高,其中‘新选048’露地堆放种茎发芽率及发芽势均最大,分别为100%和98.89%,而‘桂热3号’室内堆放发芽势和发芽率最小,分别为94.44%和77.78%。‘新选048’和‘桂热3号’露地堆放丙二醛含量比室内堆放分别降低了42.41%和48.90%,游离脯氨酸含量分别增加了10.44%和14.41%,可溶性糖含量分别增加了7.91%和9.14%,可溶性蛋白质含量分别增加了4.88%和5.36%。幼苗株高分别增加了5.78%和8.30%;茎径分别增加了10.87%和11.60%。此外,该研究还表明,‘新选048’比‘桂热3号’发芽快,长势较好,抗逆性也较强。     

土壤水分胁迫对不同肥水类型冬小麦品种花后光合特性及产量的影响

为给小麦抗旱育种和节水高产栽培提供理论和技术支持,以山东省6个不同肥水类型的冬小麦品种（‘青麦6号’、‘鲁麦21’、‘烟农21’、‘烟农24’、‘济麦22’、‘良星99’）为材料,研究了水分胁迫对冬小麦花后光合特性与产量的影响及品种间差异。结果表明,在水分胁迫条件下,各冬小麦品种花后叶面积指数、旗叶叶绿素含量、净光合速率、气孔导度、蒸腾速率和水分利用效率均有所降低,产量显著下降。品种间对水分胁迫反应差异显著,其中旱地品种‘青麦6号’在水分胁迫条件下,旗叶叶绿素含量、净光合速率、蒸腾速率、水分利用效率及气孔导度均高于其他品种,产量构成因素和产量降低幅度最小,产量最高,仅比同期水分处理下降了14%。     

改良微气调沙藏法贮藏板栗的研究

在传统沙藏法基础上,运用介质散热装置和PE薄膜覆罩研制出改良微气调沙藏法,并对板栗贮藏介质温度、呼吸强度、气体成分、品质变化及贮藏效果进行试验。结果表明,利用介质散热装置与0.04mmPE覆膜处理作用的改良微气调沙藏法,有效地改善了板栗贮藏环境,能使其保持适宜的温度、湿度、O2与CO2浓度比例,其贮藏品质得到改善,经120天常温贮藏,商品果率达93.4%。     

Chromosomal location of powdery mildew resistance genes in common wheat (Triticum aestivum L. em. Thell.) 3. Gene Pm22 in cultivar Virest

Summary Common wheat cultivar Virest possesses mildew resistance which is different from resistances expressed by currently documented mildew resistance genes, detected by response to eleven differential wheat powdery mildew isolates. F₂ populations from hybrids of the 21 Chinese Spring monosomic lines with Virest revealed one major dominant gene, located on wheat chromosome 1D. The new gene is designated Pm22. Italian cultivars Elia, Est Mottin, Ovest and Tudest also showed the disease response pattern corresponding to Virest.