Fruit Tree Crops Research Articles

Effects of Plasma-Activated Water on Leaf and Fruit Biochemical Composition and Scion Growth in Apple.

The application of plasma-activated water (PAW) in agriculture has gained the attention of researchers and practitioners. In particular, treatment with PAW is a promising method for increasing scion and rootstock survival as well as augmenting the mineral nutrition applicable to tree fruit crops. However, the applications of PAW are hampered by the lack of information about the effects of PAW on apple tree condition and yield. The increase in survival rate by PAW is believed to stem from the general stimulation of physiological processes in the plant tissue. To assess the actual effect of the PAW treatments, one needs to consider an important indicator of young tree quality such as their vegetative growth. We conducted field experiments to study the possibility of use of PAW for increase in primary nutrient contents in fruits and leaves in an orchard, as well as to assess the scion survival rate and vegetative growth of young grafts in a nursery. The application of PAW influenced the fruitset, yield, leaf nitrogen (N) and potassium (K), fruit phosphorus (P), calcium (Ca) ascorbic acid (AA) and titratable acidity (TA). Treatment with PAW did not significantly reduce the negative impact of the rootstock thickness on the survival rate of bench grafts and their subsequent development. At the same time, scion survival tended to increase in the case when the scions and the rootstocks were of compatible thickness. Further studies of the PAW treatment effects are needed to better understand its applicability in diverse fields of horticulture.

Cross species extrapolation of the disruption of thyroid hormone synthesis by oxyfluorfen using in vitro data, physiologically based pharmacokinetic (PBPK), and thyroid hormone kinetics models

The thyroid hormones play key roles in physiological processes such as regulation of the metabolic and cardiac systems as well as the development of the brain and surrounding sympathetic nervous system. Recent efforts to screen environmental chemicals for their ability to alter thyroid hormone synthesis, transport, metabolism and/or function have identified novel chemicals that target key processes in the thyroid pathway. One newly identified chemical, oxyfluorfen, is a diphenyl-ether herbicide used for control of annual broadleaf and grassy weeds in a variety of tree fruit, nut, vine, and field crops. Using in vitro high-throughput screening (HTS) assays, oxyfluorofen was identified to be a potent inhibitor of the thyroidal sodium-iodide symporter (NIS). To quantitatively assess this inhibition mechanism in vivo, we extrapolated in vitro NIS inhibition data to in vivo disruption of thyroid hormones synthesis in rats using physiologically based pharmacokinetic (PBPK) and thyroid hormone kinetics models. The overall computational model (chemical PBPK and THs kinetic sub-models) was calibrated against in vivo data for the levels of oxyfluorfen in thyroid tissue and serum and against serum levels of thyroid hormones triiodothyronine (T3) and thyroxine (T4) in rats. The rat thyroid model was then extrapolated to humans using human in vitro HTS data for NIS inhibition and the chemical specific hepatic clearance rate in humans. The overall species extrapolated PBPK-thyroid kinetics model can be used to predict dose–response (% drop in thyroid serum levels compared to homeostasis) relationships in humans. These relationships can be used to estimate points of departure for health risks related to a drop in serum levels of TH hormones based on HTS assays in vitro to in vivo extrapolation (IVIVE), toxicokinetics, and physiological principles.

Study of the population dynamics of phytoseiid mites on citrus under natural conditions

Citrus is the most extensively produced tree fruit crop in the world, and the citrus red mites, Panonychus citri (McGregor) and citrus rust mites, Phyllocoptruta oleivora (Ashmead) are the serious pest mites of citrus crops. Except for chemical control, biological control is an important component of integrated pest management and plays an essential role in regulating populations of pest mites. Predatory mites from the family Phytoseiidae are important natural enemies. The populations of P. citri are usually controlled by indigenous predators, mainly the phytoseiid mites. As native phytoseiids are more likely to adapt to the local environmental conditions than the commercially available phytoseiids, conservation of local phytoseiid species is a key factor for the IPM success in citrus orchards. Investigation into the species and population dynamics of phytoseiid mites in citrus orchards will provide important references to the conservation and utilization of predatory mites. This work aimed to investigate the species of phytoseiid mites and their seasonal population dynamics associated with P. citri in different citrus cultivars orchards. We sampled phytoseiid mites from orchards planted with three citrus cultivars of citron-lemon, Ehime Kashi No. 28 and Shatangju, respectively, from April to December in 2018⁓2021. Species of phytoseiid mites, and their developmental stage and gender were identified under a microscope. In the citron-lemon orchard, we recorded nine phytoseiid species in 2018, but only three species in 2019. The dominant species was Scapulaseius newsami (Evans). In 2020, five species with a dominant species of Euseius nicholsi (Ehara et Lee) were found in Ehime Kashi No. 28 orchard, but only two with a dominant species of Neoseiulus californicus (McGregor) detected in the Shatangju orchard. In the Shatangju orchard in 2021, six species were recorded with N. californicus being dominant from April to July, and Amblyseius eharai Amitai & Swirski being dominant from August to December. The population of predatory mites peaked in May and October in the citron-lemon orchard, and in May, July and October in the Ehime Kashi No. 28 and Shatangju orchards. All active life stages (i.e., larva, nymph and adult) were found and most were adults. The sex ratio was female-biased (over 80%) in each orchard. In conclusion, the population size of phytoseiids changed over the growing seasons. Whether this could be attributed to the different tolerance capacities of different species to the local climate conditions or chemical pesticides remains for future studies.

Photosynthetic characteristics, soil nutrients, and their interspecific competitions in an apple–soybean alley cropping system subjected to different drip fertilizer regimes on the Loess Plateau, China

Imprecise irrigation hinders the sustainable development of the fruit tree–crop intercropping system in the Loess Gully Area of China. Drip fertigation was applied for two years as part of an apple–soybean intercropping system to optimize local water and nutrient management patterns. The effects of different drip irrigation and fertilizer levels on photosynthetic characteristics, soil nutrients, and their interspecific competitions were studied. The treatments were four irrigation levels, namely 60% (W1), 70% (W2), 80% (W3), and 90% (W4) of field capacity (Fc), and three nitrogen fertilization levels, namely 59 (F1), 92 (F2), and 124 kg∙ha–1 (F3). The control (CK) was a rain-fed (neither irrigation nor fertilizer) crop. The net photosynthetic rate (Pn), transpiration rate (Tr), and soybean yield (GY) increased at first, but then decreased as irrigation and fertilizer application levels rose. The partial factor productivity (PFP) decreased as fertilization increased, but the soil available nitrogen content showed the opposite trend. The soil nutrients, and soybean Pn and Tr were positively correlated with distance from the apple tree row. The interspecific competition intensity for light and soil water decreased from 2018 to 2019, while root and soil nitrate nitrogen (NN) increased. The interspecific competition correlation between the aboveground and belowground parts was weak and varied between the two intercropping years. A principal component analysis showed that treatment W3F2 had the highest comprehensive score. Thus, a combination of irrigation at 80% Fc and 92 kg∙ha–1 nitrogen fertilizer application is optimal for the system. A multiple regression analysis indicated a water input range of 4624.49–4795.75 m3·ha−1·a−1 combined with 84.10–107.27 kg·ha−1·a−1 fertilizer application was suitable for optimal irrigation and fertilization management based on the integrated benefits to root length density, GY, Pn, and PFP during the first 4–5 years of the intercropping system.

Molecular characterization of intergeneric hybrids between Malus and Pyrus.

Apple (Malus) and pear (Pyrus) are economically important fruit crops well known for their unique textures, flavours, and nutritional qualities. Both genera are characterised by a distinct pattern of secondary metabolites, which directly affect not only resistance to certain diseases, but also have significant impacts on the flavour and nutritional value of the fruit. The identical chromosome numbers, similar genome size, and their recent divergence date, together with DNA markers have shown that apple and pear genomes are highly co-linear. This study utilized comparative genomic approaches, including simple sequence repeats, high resolution single nucleotide polymorphism melting analysis, and single nucleotide polymorphism chip analysis to identify genetic differences among hybrids of Malus and Pyrus, and F2 offspring. This research has demonstrated and validated that these three marker types, along with metabolomics analysis are very powerful tools to detect and confirm hybridity of progeny derived from crosses between apple and pear in both cross directions. Furthermore, this work analysed the genus-specific metabolite patterns and the resistance to fire blight (Erwinia amylovora) in progeny. The findings of this work will enhance and accelerate the breeding of novel tree fruit crops that benefit producers and consumers, by enabling marker assisted selection of desired traits introgressed between pear and apple.

Yield estimation of Lycium barbarum L. based on the WOFOST model

Previous research about crop growth simulation and yield prediction mainly focused on annual crops with very few such studies relating to perennial fruit tree crops. In this study, field experiments were conducted in different growth periods of Lycium barbarum L. in Gansu province, China to determine and improve the initial WOFOST model parameters with combination of the time-series leaf area index (LAI) obtained from Sentinel-2 satellite and predict yields for L. barbarum shrubs at a field scale for summer fruit (SF) and autumn fruit (AF). The results showed that the performance of initial parameters established by previous research and partial measured data was relatively poor, with a relative error (RE) of 20.95% for annual yield. The simulation after model parameter calibration significantly improved model prediction accuracy. The predicted SF was 2588 kg/ha and AF was 601 kg/ha with a RE of -5.51%. This study provided a strategy to improve modelled yield for fruit tree crops through utilization of remote sensed and field measured data in model parameter calibration, which on the other hand provides useful information for regional development planning and crops marketing.

Genomic Analysis of LEA Genes in Carica papaya and Insight into Lineage-Specific Family Evolution in Brassicales.

Late embryogenesis abundant (LEA) proteins comprise a diverse superfamily involved in plant development and stress responses. This study presents a first genome-wide analysis of LEA genes in papaya (Carica papaya L., Caricaceae), an economically important tree fruit crop widely cultivated in the tropics and subtropics. A total of 28 members were identified from the papaya genome, which belong to eight families with defined Pfam domains, i.e., LEA_1 (3), LEA_2 (4), LEA_3 (5), LEA_4 (5), LEA_5 (2), LEA_6 (2), DHN (4), and SMP (3). The family numbers are comparable to those present in Ricinus communis (Euphorbiaceae, 28) and Moringa oleifera (Moringaceae, 29), but relatively less than that found in Moringa oleifera (Cleomaceae, 39) and Arabidopsis thaliana (Brassicaceae, 51), implying lineage-specific evolution in Brassicales. Indeed, best-reciprocal-hit-based sequence comparison and synteny analysis revealed the presence of 29 orthogroups, and significant gene expansion in Tarenaya and Arabidopsis was mainly contributed by whole-genome duplications that occurred sometime after their split with the papaya. Though a role of transposed duplication was also observed, tandem duplication was shown to be a key contributor in gene expansion of most species examined. Further comparative analyses of exon-intron structures and protein motifs supported fast evolution of this special superfamily, especially in Arabidopsis. Transcriptional profiling revealed diverse expression patterns of CpLEA genes over various tissues and different stages of developmental fruit. Moreover, the transcript level of most genes appeared to be significantly regulated by drought, cold, and salt stresses, corresponding to the presence of cis-acting elements associated with stress response in their promoter regions. These findings not only improve our knowledge on lineage-specific family evolution in Brassicales, but also provide valuable information for further functional analysis of LEA genes in papaya.

Impacts of land-use changes and landholding fragmentation on crop water demand and drought in Wadi El-Farigh, New Delta project, Egypt

Despite Egypt’s limited water resources, more lands in the western desert of the Nile Delta are currently being reclaimed to increase the agricultural area to feed its fast-growing population and provide jobs for new generations. These reclaimed lands are prone to drought since they are located in arid regions with limited water resources for irrigation. Moreover, a high rate of landholdings fragmentation was observed with the migration of large numbers of new farmers to the newly reclaimed areas. Hence, the current work uses remote sensing data to investigate the impacts of landholdings fragmentation and land-use changes on irrigation water demand and drought propagation in two selected sites in Wadi El-Farigh area, one of the newly reclaimed valleys in the western desert of Egypt. To achieve that goal, high-resolution satellite images were used to quantify the land-use changes and patterns. The Surface Energy Balance System (SEBS) was used to estimate the actual evapotranspiration (ETa) from 2010 to 2020. Standardized Precipitation Index (SPI) and Evaporative Stress Index (ESI) were used to monitor drought. Results indicated a large transformation of seasonal herbaceous crops to tree-fruit crops in the two study sites. However, landholding fragmentation caused a reduction in the total cultivated area and thus the accumulated water consumption over one study site. Although the accumulated ETa decreased following the decline in the total cultivated area, the ETa rate per hectare increased by 18.4% and 19.6% for trees and herbaceous crops, respectively, reflecting the negative impact of climate change. ESI and SPI time series confirms that the area became extremely dry, particularly after 2017. In conclusion, land use and climate change increased crop water demand, while landholding fragmentation led to cropland loss. Hence, more policies for land protection and adaptation strategies to climate change are essentially needed.

Genome-wide identification of the trehalose-6-phosphate synthase gene family in sweet orange (Citrus sinensis) and expression analysis in response to phytohormones and abiotic stresses.

BackgroundTrehalose-6-phosphate synthase (TPS) is an essential enzyme for synthesizing trehalose and is a significant regulator of plant development and stress response. Sweet orange (Citrus sinensis) is an economically important fruit tree crop and a common transgenic material. At present, little information is available about the TPS gene family in sweet orange.MethodsThe TPS gene family were identified from sweet orange genome by bioinformatics analysis. Additionally, the expression of CisTPS genes was analyzed under phytohormones and abiotic stresses by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR).ResultsHere, eight TPS genes were identified and were found to be randomly distributed in five sweet orange chromosomes. TPS and trehalose-6-phosphate phosphatase (TPP) domains were observed in all CisTPS proteins. The phylogenetic tree showed that CisTPS genes were divided into two subfamilies, and genes in each subfamily had conserved intron structures and motif compositions. The cis-acting elements of CisTPS genes suggested their roles in phytohormone and stress responses. All CisTPS genes were ubiquitously expressed in roots, leaves, and stems, and six members were highly expressed in roots. Expression profiles showed that CisTPS genes exhibited tissue specificity and were differentially expressed in response to phytohormones and abiotic stresses. This study lays a foundation for revealing the functions of the TPS gene family in trehalose regulation in sweet orange, and provides a valuable reference for this gene family in other plants.

Plant-Based Methodologies and Approaches for Estimating Plant Water Status of Mediterranean Tree Species: A Semi-Systematic Review

Global climate change presents a threat for the environment, and it is aggravated by the mismanagement of water use in the agricultural sector. Since plants are the intermediate component of the soil–plant–atmosphere continuum, and their physiology is directly affected by water availability, plant-based approaches proved to be sensitive and effective in estimating plant water status and can be used as a possible water-saving strategy in crop irrigation scheduling. This work consists of two parts: the first part extensively reviews the plant-based methods and approaches that are most applied to monitor the plant water status (PWS), the different technologies available, the gaps, and the possibility of further improvements in establishing a sustainable irrigation schedule. The various approaches are described, and the differences between conventional and recent improved methods are analyzed. The second part is an extensive dataset survey of 83 publications from 2012 to 2022 that applied the main monitoring methodologies and approaches for water status assessment in fruit and nut tree crops cultivated in a Mediterranean climate. The aim of this work is to serve as a practical reference to deepen reader knowledge on PWS and enhance researchers to identify gaps and potential advances in designing user-friendly monitoring technologies.

Carica papaya L.: A Tropical Fruit with Benefits beyond the Tropics

Carica papaya L. (family: Caricaceae), also known as ‘papaya,’ is a tropical American fruit tree. Due to the bioactive components (carpaines, BITC, benzyl glucosinolates, latex, papain, zeaxanthin, choline, etc.) in its seeds, leaves, and fruits, it is revered for its excellent antioxidant, digestive, and nutraceutical benefits. Papayas are high in vitamins A, B, C, E, and K, folate, pantothenic acid, zeaxanthin, lycopene, lutein, magnesium, copper, calcium, and potassium. Being rich in fiber, antioxidants, and vitamin C, it lowers the cholesterol in the arteries; prevents arthritis; reduces aging, cancer, macular degradation, risk of cardiovascular diseases, and stress; increases platelet count; controls dengue fever; facilitates digestion, and lowers body weight. Papaya leaf extract, with many in vitro and case studies in combination therapies with modern medicine, especially for cancers and many other viral diseases, has been found to be an efficient cure. Humans have cultivated papaya cultivars for millions of years because of their significant commercial, medicinal, and agronomic value. Several reports have been published on the genetic modification of papaya for resistance to abiotic (herbicide, Al toxicity, etc.) and biotic stressors (PRSV, mites, Phytophthora, etc.), delaying ripening, and improving shelf life. However, most of these traits have not been introduced globally to all commercial papaya varieties. Unraveling the genetics of papaya has shed light on various domestication impacts, evolutionary patterns, and sex determination in fruit tree crops. It also serves as a potential step toward developing new cultivars to fight climate-oriented stress. Furthermore, extensive research on the stability of the ‘transgene’ across generations, and the ‘yield-penalty’ caused by the transgene, is required. Thus, meticulous crop improvement research on commercial papaya cultivars is necessary for long-term food and health security. This review article encompasses information on the traditional and modern medicinal uses, nutritional properties, phytochemistry, diseases and etiology, post-harvest measures, genomics, biotechnological strategies (for papaya improvement), and value-added products of papaya for food and health security.

Automatic Detection of Olive Tree Canopies for Groves with Thick Plant Cover on the Ground.

Marking the tree canopies is an unavoidable step in any study working with high-resolution aerial images taken by a UAV in any fruit tree crop, such as olive trees, as the extraction of pixel features from these canopies is the first step to build the models whose predictions are compared with the ground truth obtained by measurements made with other types of sensors. Marking these canopies manually is an arduous and tedious process that is replaced by automatic methods that rarely work well for groves with a thick plant cover on the ground. This paper develops a standard method for the detection of olive tree canopies from high-resolution aerial images taken by a multispectral camera, regardless of the plant cover density between canopies. The method is based on the relative spatial information between canopies.The planting pattern used by the grower is computed and extrapolated using Delaunay triangulation in order to fuse this knowledge with that previously obtained from spectral information. It is shown that the minimisation of a certain function provides an optimal fit of the parameters that define the marking of the trees, yielding promising results of 77.5% recall and 70.9% precision.

Genomic insights into the important ornamental and stress resistance traits of Prunus mume

• Genomic insights into Prunus mume evolution and its important ornamental and stress resistance traits. • Prunus mume had completed genomic projects formation mechanism of flower aroma, flower color, flower type, plant architecture, cold resistance and other traits . Prunus mume is a traditional Chinese ornamental and fruit tree crop with a long history of cultivation and wide use in gardens. With the rapid development of biotechnology, the researchers have successively completed the whole genome sequencing and resequencing of P. mume . They have analyzed the formation mechanism of flower aroma, flower color, flower type, plant architecture, cold resistance and other traits, which lay a theoretical foundation for improving the efficiency of breeding and the molecular breeding designs. In this review paper, we briefly summarized the important research progress of P. mume genomics and molecular biology in recent 10 years, mainly including germplasm resource classification, genomic projects, genetic map, important ornamental traits and stress resistance, cultivation and promotion demonstration of new cold resistant cultivars. Furthermore, the key objectives and directions of future research from this study will contribute to accelerating breeding programs for Prunus species.

Assessment of Genetic Diversity in Plantain (Musa paradisiaca L) Using Yield-Related Agro-Morphological Traits and Microsatellite Markers

Background and Objective: Plantain (Musa paradisiaca L) remains one of themost important staple food crop and perhaps, one of the oldest cultivated fruit tree crop in the humid tropics of Africa, Central Asia, South America and the West Indies.Fourteen (14) elite plantain cultivars were evaluated for genetic diversity using agro-morphological yield related attributes and simple sequence repeat (SSR) markers.
 Materials and Methods: Six (6) microsatellite markers that showed distinct fragments varying from 50 bp to 3.0 Kbp in size of polymorphic bands were selected and used for molecular characterization and fingerprinting, while agro-morphological (yield–related) attributes assessed included bunch weight, number of hands/bunch, number of fingers/hands, number of fingers/bunch, harvest interval, length of plant cycle, pulp hardness and pulp to skin weight ratio of the elite plantain cultivars.
 Results: The total number of amplified bands (TNB), mean percentage polymorphism (%P), mean polymorphic information content (PIC), average marker index (MI) and mean gene diversity for the SSR assay were 59, 70.24%, 0.79, 3.74 and 0.832 respectively. Results of agro-morphological fingerprint study revealed a significant variations in terms of the bunch weight, number of finger per hands/bunch, number of fingers per hand, number of fingers /bunch, harvest interval, length of crop cycle, pulp hardness and pulp/wt. ratio all showed significant variations among the cultivars. The distribution of the elite cultivars along with the principal components showed cluster pattern of distribution within the study location. Principal component analysis revealed four principal components contributing 99.91% to the observed morphological variations while analysis of molecular variance revealed 96.00% contributed by molecular characteristics to observed variations. The yield displayed revealed significant contributions of bunch weight, fingers/hand and fingers/bunch as the main indices for plantain yield. The dendrograms for both morphological and molecular characteristics delineated the cultivars into four distinct cluster groups and subgroups each varying in genetic distance.
 Conclusion: These good cultivars can be exploited for the improvement of low yielding cultivars in other region to increase and improve plantain yield, promote food security and income generation especially under the present economic realities where food security is threatened by the global food crises and declining crop productivity.

Temperature requirements of Colletotrichum spp. belonging to different clades.

The fungal genus Colletotrichum includes plant pathogens that cause substantial economic damage to horticultural, ornamental, and fruit tree crops worldwide. Here, we conducted a systematic literature review to retrieve and analyze the metadata on the influence of temperature on four biological processes: (i) mycelial growth, (ii) conidial germination, (iii) infection by conidia, and (iv) sporulation. The literature review considered 118 papers (selected from a total of 1,641 papers found with the literature search), 19 Colletotrichum species belonging to eight clades (acutatum, graminicola, destructivum, coccodes, dematium, gloeosporioides, and orbiculare), and 27 host plants (alfalfa, almond, apple, azalea, banana, barley, bathurst burr, blueberry, celery, chilli, coffee, corn, cotton, cowpea, grape, guava, jointvetch, lentil, lupin, olive, onion, snap bean, spinach, strawberry, tomato, watermelon, and white bean). We used the metadata to develop temperature-dependent equations representing the effect of temperature on the biological processes for the different clades and species. Inter- and intra-clades similarities and differences are analyzed and discussed. A multi-factor cluster analysis identified four groups of clades with similar temperature dependencies. The results should facilitate further research on the biology and epidemiology of Colletotrichum species and should also contribute to the development of models for the management of anthracnose diseases.

Açık kaynak kodlu Eo-learn kütüphanesi ve çok zamanlı Sentinel-2 görüntüleri ile tarımsal ürün sınıflandırması

In this study, agricultural crop classification for 2020 was carried out in Çivril-Baklan Plain, which is located between the borders of Denizli Province, Baklan, Çal and Çivril districts. The open-source Eo-Learn library that uses machine learning and deep learning algorithms in remote sensing studies and multi-temporal Sentinel-2 images was utilized in the classification process. In this study, the parcels registered in the Farmer Registration System (FRS) were used as reference parcels and before using FRS data as ground truth data, pre-editing and rule-based deletion processes were performed. By using Light Gradient Boosting Machines (LightGBM) algorithm, agricultural product pattern classification was carried out including cereal, maize, sugar beet, sunflower, hash, vineyard, fruit tree and clover crops. Classification results were evaluated using k-fold cross-validation with an overall accuracy of %93.5. A second accuracy assessment was performed with Agricultural Insurance Parcels (TARSİM) that were not included in the classification process as training data, achieving an overall accuracy of %91.1 and Kappa coefficient of 0.89.

Inheritance of Yield Components and Morphological Traits in Avocado cv. Hass From "Criollo" "Elite Trees" via Half-Sib Seedling Rootstocks.

Grafting induces precocity and maintains clonal integrity in fruit tree crops. However, the complex rootstock × scion interaction often precludes understanding how the tree phenotype is shaped, limiting the potential to select optimum rootstocks. Therefore, it is necessary to assess (1) how seedling progenies inherit trait variation from elite ‘plus trees’, and (2) whether such family superiority may be transferred after grafting to the clonal scion. To bridge this gap, we quantified additive genetic parameters (i.e., narrow sense heritability—h2, and genetic-estimated breeding values—GEBVs) across landraces, “criollo”, “plus trees” of the super-food fruit tree crop avocado (Persea americana Mill.), and their open-pollinated (OP) half-sib seedling families. Specifically, we used a genomic best linear unbiased prediction (G-BLUP) model to merge phenotypic characterization of 17 morpho-agronomic traits with genetic screening of 13 highly polymorphic SSR markers in a diverse panel of 104 avocado “criollo” “plus trees.” Estimated additive genetic parameters were validated at a 5-year-old common garden trial (i.e., provenance test), in which 22 OP half-sib seedlings from 82 elite “plus trees” served as rootstocks for the cv. Hass clone. Heritability (h2) scores in the “criollo” “plus trees” ranged from 0.28 to 0.51. The highest h2 values were observed for ribbed petiole and adaxial veins with 0.47 (CI 95%0.2–0.8) and 0.51 (CI 0.2–0.8), respectively. The h2 scores for the agronomic traits ranged from 0.34 (CI 0.2–0.6) to 0.39 (CI 0.2–0.6) for seed weight, fruit weight, and total volume, respectively. When inspecting yield variation across 5-year-old grafted avocado cv. Hass trees with elite OP half-sib seedling rootstocks, the traits total number of fruits and fruits’ weight, respectively, exhibited h2 scores of 0.36 (± 0.23) and 0.11 (± 0.09). Our results indicate that elite “criollo” “plus trees” may serve as promissory donors of seedling rootstocks for avocado cv. Hass orchards due to the inheritance of their outstanding trait values. This reinforces the feasibility to leverage natural variation from “plus trees” via OP half-sib seedling rootstock families. By jointly estimating half-sib family effects and rootstock-mediated heritability, this study promises boosting seedling rootstock breeding programs, while better discerning the consequences of grafting in fruit tree crops.

First Report of Stemphylium eturmiunum Causing Leaf Spot and Black Spot on Apple in Zhaotong, Yunnan, China.

Apple is the largest fruit tree crop in the world, and China is the largest apple-producing County in the world. Zhaotong, Yunnan Province is a typical cold and mountainous apple-producing area in China. However, apple production is threatened by diseases during the entire growing season, and among them, apple leaf spot and fruit black spot are severe. In previous reports, the main pathogen causing apple leaf spot and fruit black spot was Alternaria sp. (Lior, et al, 2017), while different pathogens were identified. In the current study, seven red Fuji apple fruit with typical black spot samples were collected randomly in Dongda company orchard, Sujiayuan town, Zhaotong, Yunnan on March 25, 2021. The spots on the surface of these apples appear rounded, the diseased parts turn brown or black in colour and the flesh became soften and rotten. The tissues of fruit epidermis at the edge between diseased and healthy parts were cut, soaked in 75% alcohol for 30 s, washed with sterile water three times, and air-dried. Five pieces of tissue were placed on PDA medium amended with rifampicin (50 mg/ml) and incubated in the dark at 25 ℃ for 3-5 days. After colonies grew, mycelial clumps were picked out from the edges of the colonies, transferred to new PDA plates, and incubated at 25 ℃ for 6 days. The diameter of the colonies reached up to 5.7 cm. A representative isolate was retained for further work and was named P6-3-1. The hyphae were white and dense at an early stage, the culture medium on the underside became yellow and the middle parts of the colonies were darker. With maturity, hyphae were clumped, became red with other colors interspersed, and the medium became dark red. Light brown spores were produced, with more vertical septa and fewer transverse septa. Two to three transverse septa were generally observed with obvious constriction at the transverse septa. Average spore size was 22.83 µm ± 2.04 µm × 14.58 µm ± 1.97 µm. DNA was extracted from mycelium, purified and amplified with two pairs of primers, ITS1/ITS4 (White et al. 1990) and gpdF/gpdR (Marcos P. S. Câmara, et al. 2002). The PCR products were sequenced and deposited in GenBank (accession NO.OK560128 and OK627661 ). The similarity of ITS sequences between the isolate and MH843733 (Stemphylium eturmiunum strain ST14) was 100%, and that of gpd sequences between the isolate and MH843728 (Stemphylium eturmiunum strain ST20) was 100%. The maximum parsimony method of Mega7.0 was used and demonstrated that the studied isolate converged to the same branch as Stemphylium eturmiunum. Koch's postulates was applied to identify the pathogenicity of this isolate. A disc of P6-3-1-culture on PDA (5 mm in diameter) was placed on apple leaves and fruit wounds. Sterile PDA was used as a control. All plants were kept in a growth chamber at 25-30 ℃. Four days after inoculation, the disease spot was observed on the inoculated sites and fruit, and with the extension of incubation time, the diseased spots continue to grow, and the leaf spots were not limited by the veins. The pathogen was re-isolated from the inoculated leaves and fruit, satisfying Koch's postulates. This pathogen can also cause postharvest rot of sweet cherry (Alice Spadoni, et al, 2020), postharvest rot on tomato (Prencipe Simona, et al, 2021), etc. This is the first report that Stemphylium eturmiunum can cause apple leaf spot and fruit black spot in Yunnan province, China. The apple black spot caused by Stemphylium eturmiunum was accurately identified. By distinguishing between the two similar diseases mentioned above, resistance to the host and management practices can be accrued based on the characteristics of the pathogen, its epidemiological pattern and the choice of an effective chemical fungicide.

Feasibility of Mechanical Pollination in Tree Fruit and Nut Crops: A Review

Pollination is essential for the production of most fruit and nut crops, yet it is often a limiting factor for both yield and product quality. Mechanical pollination (MP) systems offer the potential to increase productivity of a broad range of horticultural fruit and nut crops, and to manage the risk of reliance on current insect pollination services. To date, commercial MP systems have been developed for only a few crops (e.g., kiwifruit and date palm), suggesting that innovation in the use of MP systems has been stymied. Here, we review published and ‘grey’ literature to investigate the feasibility of MP systems of economically important tree fruit and nut crops. This review found that, whilst MP systems are a commercial reality for a wider range of fruit crops (e.g., sweet cherry) than nut crops (e.g., almond), promising results have been achieved at the experimental scale. Further we identified that the key barriers for progressing MP systems more widely include knowledge gaps in pollination biology, particularly of emerging fruit and nut species that are grown outside their native distributions, and access to proprietorial knowledge gained by commercial operators. What continues to remain unclear is detailed knowledge of the commercial development of MP systems and therefore, the opportunities to apply this knowledge to other tree crops where effective pollination limits yield and quality.

Breeding and genetics of disease resistance in temperate fruit trees: challenges and new opportunities.

Climate change, large monocultures of disease-susceptible cultivars, overuse of pesticides, and the emergence of new pathogens or pathogenic strains causing economic losses are all major threats to our environment, health, food, and nutritional supply. Temperate tree fruit crops belonging to the Rosaceae family are the most economically important and widely grown fruit crops. These long-lived crops are under attack from many different pathogens, incurring major economic losses. Multiple chemical sprays to control various diseases annually is a common practice, resulting in significant input costs, as well as environmental and health concerns. Breeding for disease resistance has been undertaken primarily in pome fruit crops (apples and pears) for a few fungal and bacterial diseases, and to a lesser extent in some stone fruit crops. These breeding efforts have taken multiple decades due to the biological constraints and complex genetics of these tree fruit crops. Over the past couple of decades, major advances have been made in genetic and physical mapping, genomics, biotechnology, genome sequencing, and phenomics, along with accumulation of large germplasm collections in repositories. These valuable resources offer opportunities to make significant advances in greatly reducing the time needed to either develop new cultivars or modify existing economic cultivars for enhanced resistance to multiple diseases. This review will cover current knowledge, challenges, and opportunities in breeding for disease resistance in temperate tree fruit crops.