Deciduous Fruit Research Articles

Desempenho fisiológico e químico da cultivar de videira Flame sem sementes na presença de Paulsen 1103 como enxerto intermediário

ABSTRACT Interstock is commonly used in deciduous fruit trees as a sustainable strategy to reduce the vigor of the scion associated with the high quality of fruits. In this study, we tested the effect of Paulsen 1103 (Vitis berlandieri x Vitis rupestris) as interstock on the grafting success, growth, and the physiological and chemical parameters of Flame seedless (Vitis vinifera) grapevine grafted onto Freedom (Vitis champinii x 1613C) and Paulsen 1103 rootstocks. This study was conducted over two seasons (2019 and 2020). The results indicated that direct grafting on the Paulsen 1103 rootstock recorded the highest grafting success percentage. Moreover, the grafting success percentage increased significantly when Paulsen 1103 was used as interstock between Flame seedless and Freedom rootstock (FI/P/Fr) compared to the grafting success without Paulsen 1103 interstock (FI/Fr). Also, using Paulsen 1103 as interstock between Flame seedless scion and Freedom rootstock (FI/P/Fr) significantly reduced the morphological parameters (shoot length, leaf area and the dry weight of shoots and roots) and physiological parameters of leaf (relative water content, transpiration rate, and stomatal conductance) but significantly increased the leaf chemical content (peroxidase activity, total phenols, total proline, and total soluble sugar content) compared to values of the parameters measured in Flame seedless grafted onto Freedom rootstock (FI/Fr). Peroxidase activity could be used for predicting the degree of compatibility in grapevine grafts. This study suggested that the effect of Paulsen 1103 interstock on the vegetative growth of scion is correlated with its effect on chemical content and physiological responses of the scion.

Laboratory screening of entomopathogenic fungi and nematodes for pathogenicity against the obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae)

ABSTRACT Pseudococcus viburni (Hemiptera: Pseudococcidae), the obscure mealybug, is a serious polyphagous, cosmopolitan agricultural insect pest that affects deciduous fruit production in South Africa. The presence of the mealybug in orchards results in significant damage to crops, with economic implications. The potential use of two entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPN), as biological control agents against P. viburni, was assessed under laboratory conditions, using screening bioassays. The EPF isolates, Metarhizium robertsii (6EIKEN) and M. pinghaense (5HEID), tested at a conidial concentration of 1 × 107 conidia/ml, proved to be effective against the adult stage female mealybugs, causing 96% ± 6% and 91% ± 13% mortality, respectively, 7 days post inoculation, when incubated at 25°C with humidity levels of > 95%. Heterorhabditis indica, applied at a concentration of 200 infective juveniles per insect, was found to be the most effective EPN against P. viburni, causing 79% mortality, 48 h post inoculation, while incubated at 25°C. Further bioassays showed a positive correlation between insect mortality and conidial concentration as well as exposure time. The study represents the first report on the pathogenicity of multiple local and commercial EPF isolates to control P. viburni and several local EPN isolates against P. viburni.

Revealing the Genetic Components Responsible for the Unique Photosynthetic Stem Capability of the Wild Almond Prunus arabica (Olivier) Meikle.

Almond [Prunus dulcis (Mill.) D. A. Webb] is a major deciduous fruit tree crop worldwide. During dormancy, under warmer temperatures and inadequate chilling hours, the plant metabolic activity increases and may lead to carbohydrate deficiency. Prunus arabica (Olivier) Meikle is a bushy wild almond species known for its green, unbarked stem, which stays green even during the dormancy period. Our study revealed that P. arabica green stems assimilate significantly high rates of CO2 during the winter as compared to P. dulcis cv. Um el Fahem (U.E.F.) and may improve carbohydrate status throughout dormancy. To uncover the genetic inheritance and mechanism behind the P. arabica stem photosynthetic capability (SPC), a segregated F1 population was generated by crossing P. arabica to U.E.F. Both parent’s whole genome was sequenced, and SNP calling identified 4,887 informative SNPs for genotyping. A robust genetic map for U.E.F. and P. arabica was constructed (971 and 571 markers, respectively). QTL mapping and association study for the SPC phenotype revealed major QTL [log of odd (LOD) = 20.8] on chromosome 7 and another minor but significant QTL on chromosome 1 (LOD = 3.9). As expected, the P. arabica allele in the current loci significantly increased the SPC phenotype. Finally, a list of 64 candidate genes was generated. This work sets the stage for future research to investigate the mechanism regulating the SPC trait, how it affects the tree’s physiology, and its importance for breeding new cultivars better adapted to high winter temperatures.

First report of Anthracnose on Peach Fruit Caused by Colletotrichum siamense in Uruguay.

Peach (Prunus persica L.) is an economically important deciduous fruit crop in Uruguay. Anthracnose caused by species of the genus Colletotrichum is one of the major diseases in peach production, originating significant yield losses in United States (Hu et al. 2015), China (Du et al. 2017), Korea (Lee et al. 2018) and Brazil (Moreira et al. 2020). In February 2017, mature peach fruits cv. Pavia Canario with symptoms resembling anthracnose disease were collected from a commercial orchard located in Rincon del Colorado, Canelones, in the Southern region of Uruguay. Symptoms on peach fruit surface were characterized as circular, sunken, brown to dark-brown lesions ranging from 1 to 5 cm in diameter. Lesions were firm to touch with wrinkled concentric rings. All lesions progressed to the fruit core in a V-shaped pattern. The centers of the lesions were covered by orange conidial masses. Monosporic isolates obtained from the advancing margin of anthracnose lesions were grown on PDA at 25ºC and 12h photoperiod under fluorescent light. The representative isolates DzC1, DzC2 and DzC6 were morphologically and molecularly characterized. Upper surface of colonies varied from white or pale-gray to gray and on the reverse dark-gray with white to pale-gray margins. Conidia were cylindrical, with both ends predominantly rounded or one slightly acute, hyaline and aseptate. The length and width of conidia ranged from 9.5 to 18.9 µm (x ̅=14.1) and from 3.8 to 5.8 µm (x ̅=4.6), respectively. The ACT, βTUB2, GAPDH, APN2, APN2/MAT-IGS, and GAP2-IGS gene regions were amplified and sequenced with primers ACT-512F/ACT-783R (Carbone and Kohn, 1999), BT2Fd/BT4R (Woudenberg et al. 2009), GDF1/GDR1 (Guerber et al. 2003), CgDLR1/ColDLF3, CgDLF6/CgMAT1F2 (Rojas et al. 2010) and GAP1041/GAP-IGS2044 (Vieira et al. 2017) respectively and deposited in the GenBank database (MZ097888 to MZ097905). Multilocus phylogenetic analysis revealed that Uruguayan isolates clustered in a separate and well supported clade with sequences of the ex-type (isolate ICMP 18578) and other C. siamense strains (isolates Coll6, 1092, LF139 and CMM 4248). To confirm pathogenicity, mature and apparently healthy peach fruit cv. Pavia Canario were inoculated with the three representative isolates of C. siamense (six fruit per isolate). Fruit were surface disinfested with 70% ethanol and wounded with a sterile needle at two equidistant points (1 mm diameter x 1 mm deep). Then, fruit were inoculated with 5 µl of a spore suspension (1×106 conidia mL-1) in four inoculation points per fruit (two wounded and two unwounded). Six fruit mock-inoculated with 5 µl sterile water were used as controls. Inoculated fruit were placed in moist chamber and incubated at 25°C during 10 days. Anthracnose lesions appeared at 2 and 4 days after inoculation in wounded and unwounded points, respectively. After 7 days, disease incidence was 100% and 67% for wounded and unwounded fruit, respectively. The control treatment remained symptomless. The pathogens were re-isolated from all lesions and re-identified as C. siamense. C. siamense was previously reported in South Carolina causing anthracnose on peach (Hu et al. 2015). To our knowledge, this is the first report of anthracnose disease on peach caused by C. siamense in Uruguay. Effective management strategies should be implemented to control anthracnose and prevent the spread of this disease to other commercial peach orchards.

Occurrence of Canker and Wood Rot Pathogens on Stone Fruit Propagation Material and Nursery Trees in the Western Cape of South Africa.

Dieback and canker of young stone fruit trees can cause suboptimal growth and even death under severe conditions. One source of inoculum of canker pathogens could be through nursery trees harboring latent infections that would not be visible to inspections done according to the deciduous fruit scheme. The objectives of this study were to identify the canker and wood rot fungal pathogens present in nursery stone fruit trees as well as in propagation material and to evaluate their pathogenicity. Isolations were made from scion and rootstock propagation material and from certified nursery stone fruit trees. The plant material sampled did not have any external symptoms. The certified nursery trees when cross-sectioned displayed brown discoloration from the pruning wound, the bud union, and often the crown. Fungal species isolated were identified by sequencing of the relevant barcoding genes and phylogenetic analyses thereof. Canker- and wood rot-associated fungi were identified. Buds used for budding had low levels of infection, with 1.2% of dormant buds infected and 0.4% of green buds infected. The dormant rootstock shoots had a canker pathogen incidence of 6.2% before they were planted in the nursery fields and increased inasmuch as the ungrafted, rooted rootstock plants had 11.1% infection with canker and wood rot pathogens. Out of 1,080 nursery trees, the canker- and wood rot-associated fungi infected 21.8% of trees. The canker-causing pathogens that were isolated the most were Cadophora luteo-olivacea and Diplodia seriata. A low incidence of wood rot fungi was found, with only 1.5% of nursery trees infected. In total, 26 new reports of fungal species on stone fruit in South Africa were made. Of these, 22 have not been found on stone fruit worldwide. The pathogenicity trials' results confirmed the pathogenic status of these newly reported species. All of the isolates tested formed lesions significantly longer than the control, 4 months after wound inoculation of 2-year-old shoots of two plum orchards. Lasiodiplodia theobromae was the most virulent species on both plum cultivars. The results of this research showed that nursery stone fruit trees and propagation material can harbor latent infections. Different management practices need to be evaluated to prevent these infections to ensure healthier stone fruit nursery trees.

Hepatoprotective activity of Flacourtia jangomas (Lour.) Raeuschleaves and fruit methanolic extract on paracetamol-induced hepatotoxicity in HepG2 Cells

Introduction and Aim: Plants have become the current focus of research in treating the various diseases and ailments. Flacourtia jangomas (Lour.) Raeusch belongs to the familySalicaceae. Itis a small deciduous fruit tree having immense nutritional and medicinal significance. Different parts of the plant are pharmaceutically used forcuring various ailments. In this study, we investigated the hepatoprotective activity of Flacourtia jangomas (Lour.) Raeusch leaves and fruit methanolic extract on Paracetamol induced HepG2 cell line.
 
 Methods: The cytotoxic and hepatoprotective properties were evaluated by measuring cell viability; activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH); lipid peroxidation (malondialdehyde (MDA) levels).
 
 Results:The increased cell viability of 140.43± 4.07% and 133.93±3.20%was observed in HepG2 cells treated with methanolic extract of F. jangomas leaf and fruit extract respectively at 10µg/ml concentration and then decreased along with the rise of F. jangomas leaf and fruit extract concentrations. The level of LDH, ALT, AST and MDA decreased after F. jangomas leaf and fruit treatment compared to negative control.
 
 Conclusion: This study suggests that the methanolic Extract of F. jangomas (Lour.) Raeusch leaves(FJL)and fruit (FJF) shows hepatoprotective activity in Paracetamol induced HepG2 cell line by the decrease in AST and ALT activities and LDH and MDA level. Hence, it could be considered as a therapeutic agent in curing liver-related diseases.

Compatibility of Jatropha curcas seed extract and entomopathogenic fungus Akanthomyces lecanii against the citrus red mite Panonychus citri

ABSTRACT The citrus red mite (CRM), Panonychus citri (McGregor) (Acari: Tetranychidae), is a pervasive pest of numerous deciduous and evergreen fruit trees. The persistent use of acaricides in controlling the mite has been known to cause unwanted negative impacts. In this study, the bio-efficacy of individual and combined application of Jatropha curcas seed extract (JcSE) (Euphorbiaceae) and entomopathogenic fungus Akanthomyces lecanii (Cordycipitaceae) on the mortality and oviposition rate of CRM was investigated. The effects of JcSE on A. lecanii were initially evaluated by incorporating JcSE into potato dextrose agar medium at various concentrations. After that, A. lecanii was inoculated on the medium, and its mycelial growth, conidia production, and conidia viability were observed. The results indicated that JcSE at all concentrations had no deleterious effects on the fungus, illustrating high compatibility and suggesting their combined application. The application of JcSE and A. lecanii increased the CRM mortality and reduced the mite oviposition rate, both when applied singly and in combinations. At 144 h after application, their combined application at the highest concentration used caused 97.5% mortality of CRM and decreased the mite oviposition rate to 0.5 eggs, while the mite mortality and oviposition rate were 2.5% and 38.7 eggs, respectively, in control. Therefore, the combined application of JcSE and A. lecanii can be considered as a promising option in integrated management programmes of CRM, particularly in organic farming.

Ethephon-Mediated Bloom Delay in Peach Is Associated With Alterations in Reactive Oxygen Species, Antioxidants, and Carbohydrate Metabolism During Dormancy.

Ethephon (ET) is an ethylene-based plant growth regulator (PGR) that has demonstrated greater efficacy in delaying bloom in deciduous fruit species. However, the underlying mechanisms by which ET modulates dormancy and flowering time remain obscure. This study aimed to delineate the ET-mediated modulations of reactive oxygen species (ROS), antioxidants, and carbohydrate metabolism in relation to chilling and heat requirements of “Redhaven” peach trees during dormancy. Peach trees were treated with ethephon (500ppm) in the fall (at 50% leaf fall), and floral buds were collected at regular intervals of chilling hours (CH) and growing degree hours (GDH). In the control trees, hydrogen peroxide (H2O2) levels peaked at the endodormancy release and declined thereafter; a pattern that has been ascertained in other deciduous fruit trees. However, H2O2 levels were higher and sustained for a more extended period than control in the ET-treated trees. ET also increased the activity of ROS generating (e.g., NADPH-oxidase; superoxide dismutase) and scavenging (e.g., catalase, CAT; glutathione peroxidase) enzymes during endodormancy. However, CAT activity dropped significantly just before the bud burst in the ET-treated trees. In addition, ET affected the accumulation profiles of starch and soluble sugars (hexose and sucrose); significantly reducing the sucrose and glucose levels and increasing starch levels during endodormancy. However, our study concluded that variations in ROS levels and antioxidation pathways, rather than carbohydrate metabolism, could explain the differences in bloom time between ET-treated and -untreated trees. The present study also revealed several important bud dormancy controlling factors that are subject to modulation by ethephon. These factors can serve as potential targets for developing PGRs to manipulate bloom dates in stone fruits to avoid the ever-increasing threat of spring frosts.

The Mycobiota of High Altitude Pear Orchards Soil in Colombia.

Simple SummarySoil fungi are extremely important in the agro-environment. They are among the main decomposers of organic matter, contributing to carbon, nitrogen, and phosphorous cycles. They often establish positive relationships with plants, protecting them from pathogens and abiotic stresses. This study aimed to uncover the soil fungal communities of two high altitude pear orchards with biomolecular techniques. We found a rich and diverse assemblage, dominated by fungi belonging to Ascomycota and Mortierellomycota. Most of the found species were novel records for soil fungi in Colombia. The most common fungal genera were Mortierella, Fusarium, Pseudaleria and Cylindrocarpon. Among the identified fungi, some species are known to be bioactive, with promising activities as biocontrol agents, plant-growth promoters, and producers of valuable substances. These results could contribute for a more attentive management of Colombian pear orchards in future and an enrichment of knowledge on Colombian biodiversity.In Colombia, the cultivation of deciduous fruit trees such as pear is expanding for socio-economic reasons and is becoming more and more important for the local population. Since organized cultivation is slowly replacing sustenance cultivation, scientific information on the present agro-environment is needed to proceed in this change in an organic and environmentally friendly way. In particular, this study is an accurate description of the mycobiota present in the bulk soil of two different high altitude pear orchards in the Colombian Andes. The metabarcoding of soil samples allowed an in-depth analysis of the whole fungal community. The fungal assemblage was generally dominated by Ascomycota and secondly by Mortierellomycota. As observed in other studies in Colombia, the genus Mortierella was found to be especially abundant. The soil of the different pear orchards appeared to host quite different fungal communities according to the soil physico-chemical properties. The common mycobiota contained 35 fungal species, including several species of Mortierella, Humicola, Solicoccozyma and Exophiala. Moreover, most of the identified fungal species (79%) were recorded for the first time in Colombian soils, thus adding important information on soil biodiversity regarding both Colombia and pear orchards.

Factors shaping soil organic carbon stocks in grass covered orchards across China: A meta-analysis

Orchard grass coverage has been widely adopted to increase fruit yield by improving soil fertility. However, the impact of the environment on the changes in soil organic carbon (SOC) stocks consecutive to orchard grass coverage remain poorly quantified at a large scale. The present study aimed to examine the responses of SOC stocks to grass coverage at a soil depth of 0–30 cm in orchards compared to clean tillage. A total of 342 observations across China from 139 peer-reviewed publications were subjected to meta-analysis. Aggregated boosted tree analysis was performed, evaluating the determinants of SOC stocks, such as plant traits (e.g., fruit tree type, grass type, orchard age, and grass age), edaphic variables (e.g., initial SOC and nitrogen concentration, soil pH, and soil clay content), climatic factors (e.g., mean annual precipitation (MAP) and mean annual temperature (MAT)), and management practices (e.g., grass source, grass growing mode, fertilization, grass mowing, placement of mowed residues, and irrigation). On average, orchard grass coverage significantly enhanced SOC stocks by 21.47% (percentage change) compared to clean tillage. Biotic and abiotic factors influenced this increase in SOC stocks following grass coverage in orchards to different extents. Grass age and soil clay content were the main determinants driving the variation in the SOC stocks following grass coverage in orchards. Thus, we propose an efficient way to optimize C sequestration in grass covered orchards, regarding plant traits, climatic factors, edaphic variables, and management practices. Longer than 12 months of surface grass coverage with cultivated grass species in mature deciduous fruit orchards (≥5 years) efficiently increased SOC stocks. This is particularly the case for acidic (pH < 6.5) soils with low C content (SOM < 15 g kg−1) in areas with suitable rainfall and temperature conditions (MAP ≥ 400 mm, MAT ≥ 10 °C). Collectively, this meta-analysis identified orchard grass coverage as a promising practice for significantly increasing SOC stocks at 0–30 cm across large geospatial locations in China.

Varietal Impact on Suitability and Acceptability of Mulberry (Morus alba) Fruit Drinks: A Comparative Study

Mulberry (Morus alba) is a deciduous fruit that has therapeutic benefits owing to significant amounts of bioactive compounds like anthocyanins, flavonoids and phenolic compounds. This study was designed to assess the varietal comparison of mulberry drinks. At first, mulberry fruit pulp was prepared and then evaluated for its nutritional composition. The pH was found high (6.1±0.01) in green variety compared to the pH (5.1±0.07) of red variety. Similarly, total soluble solids, crude fat, crude protein and antioxidant activity were found to be higher in the green variety compared to the red variety. The physicochemical results indicated that pH, total soluble solids, crude protein and total phenolic contents were higher in the green variety of mulberry fruit drink than red variety. Mineral analysis also showed that green mulberry drink contained higher mineral contents over the red mulberry drink. The outcome of sensory analysis demonstrated that; although both drinks were acceptable, comparatively green mulberry drink was more accepted by consumers than the red mulberry drink.

Developmental Stages and Life Table Parameters of the Two Spotted Spider Mite,Tetranychus Urticae Koch (Acari: Tetranycidae) On Different Eggplant Genotypes.

The two-spotted spider mite, Tetranychus urticae Koch. (Acari: Tetranychidae) is considered one of the most serious pests all over the world and attacked about 1200 species of plants. It causes damage to vegetables, beans, peas, hops, grapes, deciduous fruit trees and many other fruit and flowers. Also, it prefers some genotypes of a plant to other genotypes of the same plant. This study is concerned mainly with evaluating the less favorite eggplant genotype to T. urticae and the best type for agriculture and find out the possible reason behind this preference. The longest life cycle was recorded for Rima F1 that was11.20 days and the shortest was 8.93 days for Rondona F1. Also, Rima F1 had the longest generation of 12.37 days and Rondona F1 had the shortest generation 10.37 days. The fecundity of females feed on leaves of Rondona F1 was the highest at 101.14 eggs/ female. So the results proved that Rima F1 was less affected by T. urticae. The possible reason for this preference is that Rima F1 had the highest percentage of potassium in their leaves that provides a mechanical resistance against piercing-sucking pests including T. urticae.

Predicting chilling requirement of peach floral buds using electronic nose

Chilling requirement is an important agronomic trait of peach and other deciduous fruit trees. It is a quantitative indicator of natural dormancy and its release in a low temperature environment. It is directly related to the distribution area of fruit trees and the success of cultivation. Therefore, chilling requirement evaluation is very important for cultivar breeding and plant introduction. The existing evaluation method has obvious disadvantages such as harsh conditions, complex operation and time-consuming, which greatly prolong the evaluation process. Chilling requirement of peach floral buds could be quickly estimated by a portable E-nose (PEN3.5). The ratio R of the actual accumulated chilling hours during any period of the dormancy and release process to the chilling requirement was used to indicate the stage of chilling accumulation. 5 stages were set as the R value was 0 (StageⅠ), 0.4 (Stage Ⅱ), 0.8 (Stage Ⅲ), 1.0 (Stage Ⅳ) and 1.2 (Stage Ⅴ). Volatile compounds from the floral buds of 9 cultivars with known chilling requirements at the five stages were tested, and the signals of 10 types of sensors were different. Broad-methane gradually decreased during the dormancy process, and reached the bottom at dormancy release, with a significant difference in each stage (p<0.05), while it increased significantly after dormancy release (p<0.05). The sulphur-organic compound showed a significant decrease in the early and mid-term of dormancy (p<0.05), while stayed in relatively high content during and after the release (p<0.05). Methane-aliph slightly increased during the dormancy and reached the highest content at dormancy release, which was significantly different from that in the initial period of dormancy (p<0.05), and significantly decreased after the dormancy was released (p<0.05). So the three types of compounds could be used as the metabolic markers for different stages of dormancy and release. PCA and LDA analysis indicated that the 5 stages could be clearly distinguished. PLSR analysis was performed on the R value and volatile compounds content indicating by the response of sensors, and the quantitative model was established. Cultivars with different chilling requirements were used to validate the model, and it was found that there was no significant difference between predicted chilling accumulation and chilling requirement estimated by traditional method (p>0.05). It proved that the model established in this paper can be used to evaluate the chilling requirement of peach floral buds. This is the first time that E-nose detection and PLSR quantitative analysis model are combined to be used in the estimation of chilling requirements and have achieved efficient and convenient evaluation. It has a high potential to be applied in the evaluation of peach chilling requirements in the future. And for other deciduous fruit trees or plants, the innovative method is of great reference significance.

Pruning Wastes From Fruit Trees as a Substrate for Pleurotus ostreatus

Abstract Plant material obtained by pruning and production of deciduous fruit trees was evaluated as substrates for the production of the oyster mushroom, Pleurotus ostreatus . Lignified branches and stems from peach, apple, and pear trees were processed using a ripping machine to reduce the size of chips and to optimize disinfection. A completely randomized experimental design was proposed with six treatments (novel substrates) and one absolute control (100% hay substrate). Morphological variables such as thickness and diameter of the pileus, stipe length were assessed, as well as production variables (sprouting, fresh weight, and biological efficiency) and bromatological analysis (ash, ethereal extract, crude fiber, and crude protein). Apart from the 100%-hay substrate, biological efficiency ranged between 27% (100% apple tree as the substrate) and 140% (50% hay + 50% peach tree as the substrate). According to morphological analysis, the highest diameters were recorded from mixed substrates (50% hay + 50% wood), and a highly significant positive correlation was found between diameter and stipe length. Morphological parameters were not significantly correlated with biological efficiency. Analysis of biological efficiency confirmed that mixed substrates clustered together with 100%-wood substrates. Bromatological analysis showed that the mixed substrate (50% hay + 50% pear tree) had the highest protein content among the novel tested substrates. Bromatological parameters were not significantly correlated with biological efficiency. In conclusion, pruning residues from fruit trees can be valuable by using them as substrates for the cultivation of P. ostreatus . Production is quantitatively competitive with that using hay, on the condition that wood is mixed with hay.

Plant richness and blooming cover affect abundance of flower visitors and network structure in Colombian orchards

Abstract Pollination is essential to fruit production. How plant diversity and blooming events in and around orchards affect the pollinator community and the plant‐flower‐visitor network in neotropical systems remains largely unknown. We surveyed the flower visitors in deciduous fruit trees and alternative blooming resources (other crops, hedgerows and weeds) in Colombia across 6 orchards over 12 months. We evaluated whether plant species richness and blooming cover influenced abundance and richness of flower visitors, as well as network‐level connectance and specialization. We also assessed the role of alternative blooming resources for the flower visitors of deciduous fruit trees. Overall, we found 66 taxa of flower visitors, 35 of which visited deciduous fruit trees. There was a greater abundance of flower visitors when there was higher richness of weedy species and greater blooming cover of deciduous fruit trees. Networks were less connected when there was lower crop and weedy species richness. Finally, flower visitor abundance and specialization increased when there were multiple hedgerow species in bloom with a high blooming cover. We highlight the importance of maintaining alternative blooming resources in and around the orchards to support deciduous fruit tree pollinators and diversity in the plant flower‐visitor network.

Meta-analysis of RNA-Seq studies reveals genes with dominant functions during flower bud endo- to eco-dormancy transition in Prunus species

In deciduous fruit trees, entrance into dormancy occurs in later summer/fall, concomitantly with the shortening of day length and decrease in temperature. Dormancy can be divided into endodormancy, ecodormancy and paradormancy. In Prunus species flower buds, entrance into the dormant stage occurs when the apical meristem is partially differentiated; during dormancy, flower verticils continue their growth and differentiation. Each species and/or cultivar requires exposure to low winter temperature followed by warm temperatures, quantified as chilling and heat requirements, to remove the physiological blocks that inhibit budburst. A comprehensive meta-analysis of transcriptomic studies on flower buds of sweet cherry, apricot and peach was conducted, by investigating the gene expression profiles during bud endo- to ecodormancy transition in genotypes differing in chilling requirements. Conserved and distinctive expression patterns were observed, allowing the identification of gene specifically associated with endodormancy or ecodormancy. In addition to the MADS-box transcription factor family, hormone-related genes, chromatin modifiers, macro- and micro-gametogenesis related genes and environmental integrators, were identified as novel biomarker candidates for flower bud development during winter in stone fruits. In parallel, flower bud differentiation processes were associated to dormancy progression and termination and to environmental factors triggering dormancy phase-specific gene expression.

Climate Change Impacts on Temperature and Chill Unit Trends for Apple (Malus domestica) Production in Ceres, South Africa

Climate is an essential part of crop production, determining the suitability of a given region for deciduous fruit products such as apples (Malus domestica). It influences the yield and quality of fruits. There is strong evidence of global and regional-scale climate change since the advent of the industrial era. In South Africa, mean surface temperatures have revealed a warming trend over the last century. This study aimed to assess the impact of climate change on temperature and chill unit trends for apple production in Ceres, South Africa. The daily positive Utah chill units (DPCU) model was used as frequent high temperatures can lead to a high negation volume. Historically observed (1981–2010) and future projected (2011–2100) temperatures were obtained from the South African Weather Service (SAWS) and three ensemble members of the Cubic-Conformal Atmospheric Model (CCAM), respectively. The latter employed the RCP8.5 pathway. Linear trends were calculated for temperature and accumulated PCUs for the historical base period. The probability of accumulating specific threshold PCU values for both historical and future periods was assessed from cumulative distribution functions (CDFs). The historical change in minimum temperatures showed no significant trend. Ceres revealed a warming trend in maximum temperatures over the historical period. By the 2080s, the probability of not exceeding a threshold of 1600 PCUs was exceptionally high for all ensemble members. Future projections showed a decline in the accumulated PCUs of 2–5% by the 2020s, 7–17% by the 2050s, and 20–34% towards the end of the 20th century. Based on these results, it is clear that winter chill units are negatively influenced by climate change. The loss in yield and fruit quality of apples due to climate change can negatively impact the export market, leading to significant economic losses for apple production in the Ceres area.

Comprehensive transcriptome profiling to identify genes involved in pistil abortion of Japanese apricot.

Flower development exists as a key period in the angiosperms life cycle and the proper development is considered with its reproductive success. Pistil abortion is one of the widely distributed aspects of berry plants and its basic mechanism in Japanese apricot is quite unclear and needs thorough investigation. The present study was carried out to get a deep insight into the pistil abortion mechanism in Japanese apricot using a transcriptomic approach. A large number of DEGs were identified from different development stages of normal and abortive pistils. Pair-wise comparison analysis was performed as LY1 vs DQD1, LY2 vs DQD2, and LY3 vs DQD3 and produced 3590, 2085, and 2286 transcripts, respectively. The Gene Ontology (GO) showed that different metabolic processes, plant hormones, developmental processes, and photosystem-related genes were involved in pistil abortion. The pathway analysis revealed significant enrichment of plant hormone's signal transduction and circadian rhythm pathways. Furthermore, transcription factors such as MYB, MADS-box, and NAC family showed lower expression in abortive pistils. The current study presents a new strategy for advanced research and understanding of the pistil abortion process in Japanese apricot and provides a possible reference for other deciduous fruit trees.

Determining the effect of pretreatments on freeze resistance and survival of cryopreserved temperate fruit tree dormant buds

Freeze resistance is critical to successful dormant bud (DB) cryopreservation, and is affected by genotype, environmental conditions, dormancy phase and processing techniques. Pretreatment induced freeze resistance may contribute to more successful and efficient protocols for cryopreserving DB. Differential thermal analysis (DTA) was used to quantify the effects of cryopreservation pretreatments on freeze resistance of dormant budwood. Low temperature exotherm (LTE) profiles created by DTA could rapidly identify pretreatments that are contributing to increased freeze resistance in tree fruit species. In this study, DTA was used to help elucidate the effects of varying pretreatments (sucrose, desiccation and their combination) on peach, a model crop in tree fruit physiology that has shown little cryosurvival using the DB method in the past. Post cryopreservation recovery trials using an antimicrobial forced bud development (AFBD) protocol evaluated the ability of selected pretreatments, that improved freeze resistance based on DTA, to improve recovery of dormant budwood of various deciduous tree fruit and nut species. Precryogenic exposure to sucrose solution (5.0 M, 96 h), desiccation to 30% moisture content (MC) and their combination tested for their efficacy on improving postcryogenic viability in peach, apricot, sweet cherry, little walnut, black walnut, English walnut, apple, and pear. Among the different pretreatments tested, desiccation to 30% MC had the greatest impact on increasing freeze resistance and cryosurvival across most fruit species tested and little walnut. Gradual reduction of MC (from 40 to 25%) levels increased freeze resistance in peach (R2=0.95) and increased some recovery outcomes (leaf, shoot and bud swell), however, this was not correlated with equal cryorecovery outcomes as severe bud cracking was observed. Overall, our approach linking freeze resistance and preconditioning treatments could help establish efficient species-specific cryopreservation protocols for a number of important temperate woody crops which could be recovered as complete plants by coupling AFBD and plant tissue culture.

Effect of Hydrogen Cyanamide on Bud Break, Fruit Yield and Quality of Highbush Blueberry in Greenhouse Production

Highbush blueberries need sufficient chilling exposure to induce bud break and flowering, which limits their cultivation in warm areas as well as the profitability of protected cultivation in greenhouses. Hydrogen cyanamide (H2CN2, HC), gibberellic acid (GA3), ethephon (CE), mineral oil (MO), and potassium nitrate (KNO3) are often applied to deciduous fruit trees to advance bud break and fruit set. In this study, experiments were conducted in northeast China to determine the effects of different concentrations of HC or HC in combination with GA3, CE, MO, and KNO3 on bud break, fruit quality, and fruit yield in greenhouse-grown highbush blueberry (Vaccinium corymbosum L.). The results showed that all of the treatment agents could advance bud break by at least 15 days and fruit ripening by 16 days compared to the control. In addition, all treatments could promote the development of flowers and fruits and shorten the flowering and harvest periods. Compared with the control, 0.5% HC or 0.67% HC treatment increased the fruit yield of 5-year-old and 7-year-old bushes, especially early yield. Experiments carried out over two consecutive years in two different varieties, namely ‘M7’ and ‘Brigitta’, further confirmed the positive effect of 0.67% HC application on fruit yield. The results also showed that 0.67% HC had no negative effects on fruit quality. These findings may encourage growers to consider spraying HC in greenhouses to increase fruit yield, especially early yield, in order to schedule the harvest time for a more lucrative marketing period.