Tree vegetative and generative properties and their inter-correlations for prospective apple cultivars under two training systems for young trees

Little information is available on vegetative and generative performance of apple cultivars during the early growth of trees in orchards. The aim of this five-year study was to evaluate 2 vegetative (trunk cross sectional area (TCSA) and tree height (TH)) and 7 generative parameters (tree yield (TY), fruit number per tree (FNT), crop load (CL), fruit diameter (FD), shape index (SI), fruit surface color (FSC) and fruit color intensity (FCI)) and their inter-correlations (Pearson correlation, regression analyses and PCA) for young apple trees, on 9 apple cultivars (‘Jugala’, ‘Galaval’, ‘Gala Venus Fengal’, ‘Gala Decarli-Fendeca’, ‘Gala Schnitzer (S) Schniga’, ‘Fuji September Wonder’, ‘Crimson Crisp (Co-op 39)’, ‘Jeromine’, and ‘Red Idared’) in a slender spindle training system (2597 trees ha−1) and on 4 apple cultivars (‘Wilton’s Red Jonaprince’, ‘Red Cap Valtod (S)’, ‘Early Red One’, and ‘Red Topaz’) in a super spindle training system (5194 trees ha−1) in Eastern Hungary. The strongest vegetative growth was observed in ‘Red Idared’, while the weakest was in ‘Early Red One’. Most ‘Gala’ mutants showed high yields in all years, except for ‘Galaval’. On the 6 year-old trees, the lowest tree yield was found in ‘Fuji September Wonder’ (8.2 kg tree−1), while the highest was found in ‘Gala Venus Fengal’ (35.8 kg tree−1). The lowest fruit number per tree (15 fruit tree−1) was found in ‘Jeromine’, while the highest (222 fruit tree−1) was in ‘Gala Venus Fengal’. The highest crop load was found in ‘Gala Venus Fengal’ (12.72 fruit per cm2 TCSA), while the lowest was in ‘Jeromine’ (2.13 fruit per cm2 TCSA). The smallest fruit diameter (66.3 mm) was recorded in ‘Gala Schnitzer (S) Schniga’, while highest (93.6 mm) was in ‘Red Idared’. The lowest shape index (0.73) was found in ‘Red Topaz’, while the highest (0.92) was in ‘Red Idared’. The majority of the cultivars reached very good fruit surface color (80–100%). The lowest fruit surface color (40%) was observed in ‘Gala Schnitzer (S) Schniga’, while the highest (100%) was in ‘Jeromine’ and ‘Early Red One’. The highest fruit color intensity was observed in most cultivars with the exception of ‘Jeromine’, ‘Gala Schnitzer (S) Schniga’ and’Fuji September Wonder’. In addition, correlation and regression analyses revealed strong and significant (p = 0.05) relationships between TH vs TCSA, TY vs TCSA, TH vs TY, TY vs FNT, and FCI vs FSC. PCA explained 87% of the total variance and PC1, PC2, PC3, and PC4 accounted for 33, 21, 20, and 13% of the variance, respectively, and correlated with TSCA, TH, TY and FNT; with FNT, CL and FS; with FSC and FCI; and with TH and SI, respectively. In conclusion, our study provides useful tree property data on prospective mutants/cultivars for growers/advisors in order to select the most suitable cultivars for establishing new orchards under climate conditions similar to central Europe.

Absorption and Distribution of Calcium (45Ca) Applied to the Surface of Orange (Citrus sinensis) Fruits at Different Developmental Stages

In this study, the rate of absorption and transport of calcium (Ca) in orange fruits (Citrus sinensis cv. Fukumoto) after surface treatment with 45Ca was evaluated by supplying treatments at different dates between fruit set and mid-phase II of growth (i.e., 30, 44, 66 and 99 days after full bloom, DAFB). 45Ca absorption was always detected, but 45Ca application at the fruit set was associated with the highest rates of Ca transport into the pulp (39%) compared to the other treatments (17–19%). Scanning electron microscopy SEM) images of the fruit surface showed the occurrence of stomata along with the entire rind at all the developmental stages evaluated. However, from the beginning of stage I, stomata began to collapse and develop plugs, and this became frequent as the fruit age increased. From 44 DAFB, oil gland density increased, and Ca oxalates (CaOx) were found in the fruit flavedo and albedo. Fruit Ca (not labeled) concentration increased from fruit set (30 DAFB) to 99 DAFB, although oil gland formation and rind growth and differentiation likely hindered Ca transport to internal fruit tissues (pulp). The total Ca concentration in the pedicel was always higher than that in the fruit, with no differences between the first three treatments. The information obtained in this study may be essential for improving Ca fertilizer efficacy in citrus by spray applications.

Micromorphological Characteristics of Fruit Surfaces of Some Usable Species of the Genus Valeriana (Valerianaceae) Among Ukrainian Flora

The micromorphological features of the fruit surfaces of nine species of Ukrainian flora, namely Valeriana tuberosa L., Valeriana tripteris L., Valeriana rossica P. Smirn., Valeriana stolonifera Czern., Valeriana grossheimii Worosch, Valeriana sambucifolia Mikan fil., Valeriana officinalis L. s. str., Valeriana wolgensis Kazak. [ Valeriana officinalis var. nitida (Kreyer) Rostanski], and Valeriana simplicifolia (Rchb.) Kabath, were examined. Depending on the presence and localization of pubescence on the surface of the fruit, three groups of species were distinguished: those with glabrous fruits, those with fruits pubescent only on the adaxial side, and those with fruits pubescent on both sides. Scanning electron microscopy revealed the additional characteristics of the fruits (microsculpture of the fruit surface, shape of cuticular formations on the surface of the outer periclinal walls of epidermal cells and on the surface of hairs, and structure of the stomatal complex), which were useful for the identification of the species. At the supraspecific level, the revealed features of the fruit surfaces somewhat overlapped and could be used to identify series and sections only as additional features. Based on the studied samples from herbarium material (KW), V. officinalis var. nitida was considered synonymous with V. wolgensis since there were no micromorphological differences between their fruits. The detailed micromorphological characteristics of the fruit surfaces of all the studied species can be used for further comparative morphological investigations of different aerial parts to identify stable features independent of geographic and ecological conditions.

Changes in the Fungal Community Assembly of Apple Fruit Following Postharvest Application of the Yeast Biocontrol Agent Metschnikowia fructicola

Recently, increasing focus has been placed on exploring fruit microbiomes and their association with their hosts. Investigation of the fruit surface microbiome of apple has revealed variations in the composition and structure depending on management practices, phenological stages, and spatial distribution on the fruit itself. However, the fate of the fruit surface microbiome assembly and dynamics in apple following interventions such as the application of biocontrol agents remains unknown. The objective of the study was to explore the effect of a postharvest application of a yeast biocontrol agent, Metschnikowia fructicola, on the composition of the epiphytic fungal microbiota on apples during cold storage. Our results demonstrated that the applied biocontrol agent, M. fructicola, persisted in high abundance (>28% relative abundance) on the fruit surface throughout the storage period. The biocontrol application significantly decreased the richness and caused a significant shift in the overall composition and structure of the fungal microbiome relative to untreated or water-treated controls. The yeast application reduced the abundance of several apple fungal pathogens, namely, Alternaria, Aspergillus, Comoclatris, Stemphylium, Nigrospora, Penicillium, and Podosphaera, throughout the cold storage period.

Pre- and Postharvest Management of Sunburn in ‘Granny Smith’ Apples (Malus × domestica Borkh) under Neotropical Climate Conditions

Sun damage on apples is attributed to the occurrence of high temperatures, incident radiation, and fruit and plant water parameters, all dependent on climatic conditions and management. The development of new production areas and climate changes increase the interest in studying the behavior of the fruit under different conditions. The effect on sun damage of three nets and two chemical protectants was evaluated in a commercial orchard of ‘Granny Smith’ in a neotropical climate during the 2012–2016 seasons. We recorded the evolution, incidence and severity of sunburn and sunscald. Fruit surface temperature, fruit size, sprouting and return to flowering was also recorded. Incident radiation and air temperature were considered for the assessment of the crop’s microclimate. The transmittance in PAR wavelength and the air temperature variation on netting treatments reached 0.4 and 9 °C, respectively. The fruit surface temperature for the White-Net and Black-Net-50% treatments was always lower than 46 °C. For the sun damaged fruits, the Black-Net-50% treatment showed the highest proportion of slightly sunburned fruits (94%) and the lowest proportion of heavy damages, with a sunscald index equal to or less than 2 (on a scale of 1–4) in all the tested conditions. In a neotropical climate, protectant applications did not reduce the incidence of sunburn, but with the use of nets it was possible to reduce both sunburn and sunscald without affecting growth processes dependent on leaf net assimilation.

First Report of Fusarium equiseti, Causing Fruit Rot Disease of Watermelon in Malaysia

Watermelon (Citrullus lanatus) accounts for almost 13% of all tropical fresh fruit production in Malaysia. They are grown, mostly in Johor, Kedah, Kelantan, Pahang, and Terengganu areas of Malaysia on 10,406 ha and yielding 172,722 Mt. In 2019, a new fruit rot disease was observed in two major production areas in Peninsular Malaysia. Disease symptoms included water-soaked brown lesions on the fruit surface in contact with the soil. The lesions enlarged gradually and ultimately covered the whole fruit with white mycelium leading to internal fruit decay. Disease surveys were conducted in December 2019 and November 2020 in fields at Kuantan, Pahang and Serdang, Selangor. Disease incidence was 10% in 2019 and 15% in 2020. Infected fruits were collected and washed under running tap water to wash off adhering soil and debris. Fruit tissue sections 1 to 2 cm in length were surface sanitized with 0.6% sodium hypochlorite (NaOCl) for 3 min. and washed twice with sterile distilled water. The disinfected air-dried tissues were then transferred onto potato dextrose agar (PDA) media and incubated at 25±2℃ for 3 days. Fungal colonies with whitish mycelium and pink pigment isolated using single spore culture. The pure cultures were placed onto carnation leaf agar (CLA), and the culture plates were incubated at 25±2℃ for 15 days for morphological characterization. On CLA, macroconidia were produced from monophialides on branched conidiophores in orange sporodochia. Macroconindia were thick-walled, strong dorsiventral curvature, 5 to 7 septate with a tapered whip-liked pointed apical cell and characteristic foot-shaped basal cell, 21.9 to 50.98 μm long and 2.3 to 3.60 μm wide. Typical verrucose thick chlamydospores with rough walls were profuse in chains or clumps, sub-globose or ellipsoidal. Based on morphological characteristics they were identified as Fusarium equiseti (Leslie and Summerell 2006). Molecular identification of both U4-1 and N9-1 pure culture isolates were carried out using two primer pair sets; internal transcribed spacer (ITS) ITS-1/ ITS-4 and translation elongation factor 1 alpha (TEF1-α) (EF-1/EF-2). A Blastn analysis of the ITS gene sequence of U4-1(MW362286) and N9-1 (MW362287) showed >99% similarity index to the reference gene sequence of F. equiseti isolate 19MSr-B3-4 (LC514690). The TEF1-α sequences of U4-1 (accession no. MW839563) and N9-1 (accession no. MW839564) showed 100% identity; with an e-value of zero, to the reference gene sequence of F. equiseti isolate URM: 7561 (accession no. LS398490). Each isolate also had a >99% identity with isolate NRRL 34070 (accession no. GQ505642) in Fusarium MLST database that belongs to the F. incarnatum-equiseti species complex (O’Donnell et al. 2015). Based on phylogenetic analysis of the aligned sequences (TEF1-α) by the maximum likelihood method, the U4-1 and N9-1 isolates were confirmed to be F. equiseti as was reported in Georgia, USA (Li and Ji 2015) and in Harbin, Heilongjiang Province, China (Li et al. 2018). Finally, the two pure culture isolates of U4-1 and N9-1 were used to fulfill Koch's postulates. Stab inoculations of five healthy watermelon fruits (cv. 345-F1 hybrid seedless round watermelon) were performed with a microconidial suspension of individual isolates (4x106 spores/mL). Five control fruits were stabbed with double distilled water. The inoculated fruits were incubated under 95% relative humidity at a temperature of 25±2℃ for 48 h followed by additional incubation inside an incubator at 25±2℃ for 8 days. Ten days post-inoculation, the control fruits showed no disease symptoms. However, inoculated fruits exhibited typical symptoms of fruit rot disease like water-soaked brown lesions, white mycelium on the fruit surface and internal fruit decay, which is similar to the farmer’s field infected fruits. The suspected pathogen was successfully re-isolated from the symptomatic portion of inoculated fruit and morphologically identified for verification. To our knowledge, this is the first report of F. equiseti causing fruit rot of watermelon in Malaysia. Malaysia exports watermelon year-round to many countries around the world. The outbreak of this new fruit rot disease could potentially pose a concern to watermelon cultivation in Malaysia.

Entropy-Aided Assessment of Amla (Emblica officinalis) Quality Using Principal Component Analysis

The texture analysis-based scheme for identifying non-consumable amla fruit (Emblica officinalis) samples is proposed here. The method uses entropy analysis to detect wrinkles and irregularities developed on the fruit surface with progression in time. Since entropy is one of the major tools used to detect the randomness of data, it is used here to identify these surface irregularities, which are almost absent in fresh samples. Based on these features, the edibility of the samples is predicted. Principal component analysis (PCA) further analyzes these entropy features to enhance the most important directions of variations, followed by a threshold-based segmentation scheme to detect rotten samples. The method possesses less computational burden as it applies PCA and entropy only; it is highly efficient to yield a high detection accuracy of 93.33%; hence, it is easy for real-life implementation.

First Report of Postharvest Stem End Rot of mango fruit (Mangifera indica) caused by Lasiodiplodia theobromae in China.

China is the second largest producer of mango in the world, a fruit has high nutritive value and a rich source of fiber (Kuhn et al., 2017). In late June 2019, a postharvest stem-end rot disease was observed in different local fruit markets (39°48'42.1"N 116°20'17.0"E) of the Fengtai district of Beijing, China. Black rot symptomatic lesions were observed on the fruit surface which initially started from the stem end of the mango fruit (Fig. 1). Approximately 45 % of mango fruits were affected with the disease. Symptomatic portions from collected fruit samples (n=40) were cut into small pieces (2mm2), rinsed with 1% NaClO for 20s and then washed three times with sterilized distilled water (SDW) for surface disinfection. The disinfected pieces were then placed on sterilized filter paper for drying. Later, these pieces were placed on Potato Dextrose Agar (PDA) plates and incubated at 28°C for seven days. The resulting fungal colonies were purified by the single spore isolation technique. The isolated fungal colonies were initially greenish to gray in color, later turning olive-black to black. Conidia were dark brown in color, oval-shaped, two-celled and measured 22.4 to 25.7 (24.06 ± 0.15) μm in length and 10.2 to 12.8 (11.3 ± 0.13) μm in width (n=36). Based on the symptoms, culture morphology and microscopic characters, Lasiodiplodia theobromae was suspected as the causal agent, and similar results were reported by Pavlic et al., 2004 and Burgess et al., 2006. For molecular identification, a multi-locus sequence analysis approach was used. The Internal Transcribed Spacers (ITS) region, elongation factor 1 alpha (EF1-α) and β-tubulin genes were amplified and sequenced using ITS1/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn, 1999), and Bt2a/Bt2b (Glass and Donaldson, 1995) primers respectively. The sequences of isolate MFT9 were deposited to GenBank (MW115977 (ITS), (MW118595 (EF1-α) and MW118596 (β-tubulin). All sequences showed more than 99.5% similarity with reported sequences of Lasiodiplodia theobromae isolate IBL340 with accessions numbers KT247466 (ITS), KT247472 (EF1-α) and KT247475 (β-tubulin). Phylogenetic reconstruction based on Maximum Likelihood, using Mega X (Kumar et al., 2018), grouped isolate MFT9 with isolates representing L. theobromae. Pathogenicity testing was performed on 18 fresh, healthy, medium-sized mango fruits for each treatment to fulfill Koch’s postulate. The fruits were disinfested with 1% NaClO and punctured with a sterilized needle to create approximately 2mm2 wounds for inoculation. Fruits were inoculated with 15µL of fresh inoculum (107 spores/mL) from isolate MFT9. Control fruits were inoculated with 15µL of SDW and both the inoculated and control fruits were incubated at 28°C for seven days of post inoculation. The rot lesions appeared at the point of inoculation and gradually spread on the fruit surface. The symptoms were similar to the symptoms observed on the original fruit samples (Fig. 2). This experiment was conducted three times under the same conditions, with control fruits remaining asymptomatic each time. The re-isolated fungus was identified as L. theobromae based on symptoms and morpho-molecular analysis, described above. L. theobromae is also reported as a causal agent responsible for a postharvest stem-end rot on Coconut in China (Zhang, et al., 2019). To our knowledge, this is the first report of L. theobromae causing postharvest stem-end rot of mango fruit in China. This finding suggests that L. theobromae is a potential problem for mango fruit production in China.

Fast 3D Rotation Estimation of Fruits Using Spheroid Models

Automated fruit inspection using cameras involves the analysis of a collection of views of the same fruit obtained by rotating a fruit while it is transported. Conventionally, each view is analyzed independently. However, in order to get a global score of the fruit quality, it is necessary to match the defects between adjacent views to prevent counting them more than once and assert that the whole surface has been examined. To accomplish this goal, this paper estimates the 3D rotation undergone by the fruit using a single camera. A 3D model of the fruit geometry is needed to estimate the rotation. This paper proposes to model the fruit shape as a 3D spheroid. The spheroid size and pose in each view is estimated from the silhouettes of all views. Once the geometric model has been fitted, a single 3D rotation for each view transition is estimated. Once all rotations have been estimated, it is possible to use them to propagate defects to neighbor views or to even build a topographic map of the whole fruit surface, thus opening the possibility to analyze a single image (the map) instead of a collection of individual views. A large effort was made to make this method as fast as possible. Execution times are under 0.5 ms to estimate each 3D rotation on a standard I7 CPU using a single core.