Tree Vigor Research Articles

The rootstock genotype shapes the diversity of pecan (Carya illinoinensis) rhizosphere microbial community.

Pecans (Carya illinoinensis), one of the most valuable native North American nut crops, are commonly propagated through grafting to preserve the desired characteristics from parent trees. Since successful cultivation of pecan trees relies on the interplay among scion varieties, rootstocks, and soil conditions, this study investigated the microbial change to communities in the soils and roots of southern (87MX5-1.7) and northern (Peruque) rootstocks in a rootstock test orchard. Both grafted with the 'Pawnee' scion cultivar. Bacterial 16S ribosomal RNA and fungal ITS were amplified from both roots and rhizosphere soils of the two 10-year-grafted trees, then sequenced and annotated into trophic and nutrient-related groups to characterize the rhizosphere microbiota. The Peruque roots had a higher relative abundance of saprotroph fungi, while 87MX5-1.7 exhibited higher levels of symbiotroph fungi and nitrogen fixation-related bacteria. Among them, the presence of symbiotroph fungi, particularly ectomycorrhizal fungi, notably differed between these two rootstocks, with a significantly higher presence observed in the root of 87MX5-1.7 compared to Peruque. This variation likely leads to divergent pathways of nutrient translocation: Peruque was in favor of multiple fungi (Russula and Inocybe) to gain nutrition, while 87MX5-1.7 preferred a specific domain of fungi (Tuber) and nitrogen fixation-related bacteria (Bradyrhizobia) to form beneficial symbiosis. Moreover, the presence of pathogens suggested a potential risk of Fusarium patch and snow molds in 87MX5-1.7, while canker and black foot disease pose threats in Peruque. The findings of this study suggest that rootstocks from different origins shape rhizosphere microbes differently, potentially affecting nutrient uptake and nut yield. Exploring rootstock-microbe combinations could provide insights into optimizing scion growth and ultimately increasing nut yield. By understanding how different rootstock-microbe interactions influence pecan tree development, growers can strategically select combinations that promote beneficial symbiotic relationships, enhancing nutrient uptake, disease resistance, and overall tree vigor.

Thinning followed by slash burning enhances growth and reduces vulnerability to drought for Pinus nigra.

Increasingly frequent severe drought events are pushing Mediterranean forests to unprecedented responses. Lack of management leads to dense forests that are highly susceptible to drought stress, potentially resulting in extensive dieback and increased vulnerability to other disturbances. Forest treatments like thinning and slash burning reduce competition for resources and have the potential to enhance tree growth and vigor and minimize tree vulnerability to drought. Here, we used tree rings to study the growth and physiological response of black pine (Pinus nigra) to drought in northeastern Spain under different treatments, including two thinning intensities (light and heavy, with 10% and 40% basal area reduction, respectively) followed by two understory treatments (clearing alone and in combination with slash burning), resulting in a research design of four treatments plus an untreated control with three replicates. Specifically, we studied basal area increment (BAI), resilience indices, and intrinsic water use efficiency (iWUE) using carbon and oxygen isotope composition (δ13C and δ18O in tree-ring cellulose) before and after treatments. Our results showed that BAI and resistance to drought increased in the heavy-thin (burned and unburned) and light-thin burned units. Resilience increased in the burned units regardless of the thinning intensity, while recovery was not affected by treatment. Slash burning additionally increased BAI in the light-thin and resistance and resilience in the heavy-thin units compared with clearing alone. The stable isotope analysis revealed a minor effect of treatments on δ13C and δ18O. No change in iWUE among treatments was presumably linked to a proportional increase in both net CO2 assimilation and stomatal conductance, which particularly increased in the heavy-thin (burned and unburned) and light-thin burned units, indicating that these trees were the least affected by drought. This study shows that management approaches aimed at reducing wildfire hazard can also increase the vigor of dominant trees under drought stress. By reducing competition both from the overstory and the understory, thinning followed by clearing alone or in combination with slash burning promotes tree growth and vigor and increases its resistance and resilience to drought.

Resilience of uneven-aged mixedwood stands altered by diameter-limit cutting and opportunities for their rehabilitation

Repeated diameter-limit cutting in mixedwood forests often leads to altered stand composition, quality, and regeneration, hence decreasing productivity and value over time. We studied the evolution of stand characteristics after diameter-limit cutting on a 15-year period, beginning from 11 to 43 years after cutting. We used 415 sample plots (200 m2) and three criteria: (i) ≥9.0 m2/ha overstory (trees ≥9.1 cm dbh [diameter at breast height, 1.3 m above ground]) acceptable growing stock (AGS, i.e. basal area of vigorous trees with sawlog potential), (ii) ≥3.0 m2/ha pole timber AGS (9.1 cm-23.0 cm dbh) and (iii) ≥60% sapling (dbh 1.1-9.0 cm) stocking of desired species. Stand initial quality was determined in function of overstory AGS at the beginning of the monitoring period: good quality (AGS≥9.0 m2/ha), impoverished (7.0≤AGS< 9.0 m2/ha), degraded (AGS <7.0 m2/ha). After 15 years, 47% of stands satisfied at least two criteria, but most stands (65%) had insufficient sapling regeneration. Stands in good quality and impoverished categories had sufficient basal area and AGS to support a new partial cutting cycle, contrary to stands in the degraded category. A conceptual model based on these three criteria is presented to guide silvicultural rehabilitation of uneven-aged mixedwood stands altered by past cutting practices.

Rootstock selection for ‘Swatow’ Mandarin trees grown at different locations throughout the Brazilian subtropics

Evaluating citrus rootstocks is of paramount importance in determining their suitability for a certain region and promoting resilience in orchards by increasing the genetic pool, thereby potentially contributing to a more strategic establishment of new plantings. This long-term field study (2000–2013) aimed to evaluate different rootstocks for ‘Swatow’ mandarin grown at two locations (Paranavaí and Londrina) in the Brazilian subtropics. Nine rootstocks were evaluated, including ‘Rangpur’ lime, ‘Swingle’ citrumelo, ‘Volkamer’ lemon, ‘Caipira DAC’ sweet orange, ‘Cleopatra’ and ‘Sunki’ mandarins, ‘Trifoliate’ orange, ‘Carrizo’, and ‘Fepagro C-13’ citranges. Trees were assessed for vegetative growth, yield, fruit quality, density, and yield estimates. The experimental design was a randomized block arranged in a 9 × 2 setting (rootstock × location) with 6 replicates and 4 trees per plot. ‘Swatow’ trees grew more vigorously in Londrina than Paranavaí, particularly for ‘Cleopatra’ and ‘Sunki’ pairings. Tree vigor was reduced with ‘Trifoliate’, resulting in higher tree density estimates and yield efficiency. This rootstock, along with ‘Rangpur’, ‘Swingle’, and ‘Carrizo’ provided superior yield to the scion. All tested rootstocks conferred good fruit quality. Fruits were larger and heavier in ‘Sunki’ pairings, showing higher soluble solids (SS) content, along with ‘Caipira DAC’, ‘Trifoliate’, ‘Swingle’, and ‘Carrizo’ at both locations. Our findings confirm the suitability of ‘Trifoliate’ orange, ‘Carrizo’ citrange, or ‘Caipira DAC’ orange rootstocks as promising candidates for ‘Swatow’ mandarin cultivation in humid subtropical and analogous regions. Further investigations are invoked to improve the horticultural performance of ‘Swatow’ mandarin trees grafted onto these rootstocks.

Effects of rootstocks and developmental time on the dynamic changes of main functional substances in 'Orah' (Citrus reticulata Blanco) by HPLC coupled with UV detection.

Citrus fruit is rich in important functional constituents such as flavonoids, phenolic acids terpenes and other functional substances that play an important role for treating clinical diseases or controlling major agricultural diseases and pests. Plant secondary metabolites have become one of the most important resources of novel lead compounds, especially young citrus fruits contain multiple functional substances. 'Orah', a type of citrus reticulata, is known for its fine appearance, productivity, delicious sweetness, late-maturing characteristics, and is widely cultivated in China. Fruit thinning and rootstock selection are commonly used agronomic measures in its production to ensure its quality and tree vigor. However, few studies have demonstrated the effects of these agronomic measures on the functional substances of 'Orah'. In this study, we used HPLC coupled with UV to detect the dynamic changes of fruit quality, 13 main flavonoids, 7 phenolic acids, 2 terpenes, synephrine and antioxidant capacity in both peel and pulp of citrus fruits grafted on four rootstocks (Red orange Citrus reticulata Blanco cv. red tangerine, Ziyang xiangcheng Citrus junos Sieb. ex Tanaka, Trifoliate orange Poncirus trifoliata L. Raf, and Carrizo citrange Citrus sinensis Osb.×P.trifoliate Raf) at six different developmental stages (from 90 DAF to 240 DAF). The results indicated that rootstock can significantly affect the contents of functional constituents and antioxidant capacity in 'Orah'. Additionally, it was found that pruning at either 90 DAF (days after flowering) or 150 DAF produced the most favorable outcomes for extracting functional substances. We also identified rootstock 'Trifoliate orange' has the highest total soluble solids (TSS) and 'Ziyang xiangcheng' to be the optimal in terms of comprehensive sensory of fruit quality, while 'Red orange' and 'Ziyang xiangcheng' are optimal in terms of functional substance quality, and 'Red orange' excels in antioxidant capacity. Overall, the findings demonstrate the important role of rootstocks and developmental stage in shaping fruit sensory quality and functional substance synthesis, providing valuable insights for guiding rootstock selection, determining thinning time, and utilizing pruned fruits in a more informed manner.

Irrigation is an effective strategy to assist cork oak (Quercus suber L.) regeneration in a semi-arid climate

ABSTRACT Irrigation can be a strategy to overcome the high mortality and declining vigour of cork oak trees facing increasing drought stress in the Mediterranean basin. Through a three-year irrigation experiment in a semi-arid Mediterranean region, which encompassed two sets of 100 planted individuals that had a 24-year age gap and the direct seeding of 100 acorns, we tested the influence of water irrigation on distinct stages of cork oak establishment and development, namely (1) acorn germination, (2) emerged seedling survival, (3) growth of planted seedlings, (4) vertical and (5) radial growth, and (6) the vigour of 28-year-old trees. Water irrigation significantly improved acorn germination and the growth of both cork oak seedlings and trees but did not affect the survival of emerged seedlings to the dry season. The vigour of 28-year-old trees (height-to-diameter ratio) showed no significant differences between the plants growing in watered and in controlled conditions.

Architectural approach to evaluate the design and management of almond cultivars suitable for super high-density orchards.

The almond tree is a major global nut crop, and its production has surged dramatically in recent years. Super high-density (SHD) planting systems, designed to optimize resource efficiency and enhance precocity, have gained prominence in almond cultivation. A shift in cropping systems toward sustainable intensification (SI) pathways is imperative, and so maximizing branching density within the canopies of SHD trees is crucial to establish and maintain productive potential, especially for hedge-pruned trees. This study investigates the influence of different almond cultivars grafted onto a novel growth-controlling rootstock on tree architectural and growth parameters in a SHD orchard. This open field research provided valuable insights for the development and application of new tools and methods to increase productivity and sustainability in almond growing. Three cultivars (Lauranne® Avijour, Guara Tuono, and Filippo Cea) were evaluated in Gravina in Puglia (BA) over a two-year period. Canopy growth parameters, such as canopy volume and trunk cross-sectional area, and architectural traits, like branching density, branching angle, number and length of subterminal shoots, and number of brachyblasts, were measured through qualitative and quantitative measurements. Results revealed significant differences in tree height, canopy thickness, width, volume, and vigor among the cultivars. Architectural traits, including branch parameters, brachyblast parameters, and subterminal shoots, varied among the cultivars. Lauranne displayed a more compact well-distributed canopy and exhibited the lowest vigor. Filippo Cea showed the highest vigor and the greatest canopy volume. Tuono had a higher number of buds and bud density. The best ideotype for SHD orchards is a smaller tree, with high branching density and smaller trunk diameters, i.e. the vigor. Cv. Lauranne seemed to be the best cultivar, mostly with the lowest tree vigor of all the cultivars involved. These findings provide valuable insights for almond growers and breeders seeking to optimize orchard design and management for enhanced SHD orchards productivity and sustainability. Future research will explore the relationship between canopy architecture and yield parameters, considering different scion/rootstock combinations in different environmental conditions.

PpSAUR5 promotes plant growth by regulating lignin and hormone pathways.

Peach (Prunus persica) has a high nutritional and economic value. However, its overgrowth can lead to yield loss. Regulating the growth of peach trees is challenging. The small auxin-up RNA (SAUR) gene family is the largest family of auxin-responsive genes, which play important roles in plant growth and development. However, members of this gene family are rarely reported in peach. In this study, we measured leaf area, chlorophyll and lignin content to detect the role of PpSAUR5 on growth through transgenic Arabidopsis. PpSAUR5 responds to auxin and gibberellin, promoting and inhibiting the synthesis of gibberellin and auxin, respectively. The heterologous transformation of PpSAUR5 in Arabidopsis led to enhanced growth of leaves and siliques, lightening of leaf color, decrease in chlorophyll content, increase in lignin content, abnormalities in the floral organs, and distortion of the inflorescence axis. Transcriptome data analysis of PpSAUR5 overexpression and wild-type lines revealed 854 differentially expressed genes (DEGs). GO and KEGG analyses showed that the DEGs were primarily involved in biological processes, such as cellular processes, metabolic processes, response to stimuli, and catalytic activity. These genes were mainly enriched in pathways, such as phenylalanine biosynthesis, phytohormone signaling, and MAPK signaling. In summary, these results suggested that PpSAUR5 might regulate tree vigor by modulating the synthesis of auxin and gibberellin. Future studies can use PpSAUR5 as a candidate gene to elucidate the potential regulatory mechanisms underlying peach tree vigor.

Effect of Plant Growth Regulators and Growing Media on Rooting of Cuttings in Punica granatum L. cv. Bhagwa

Background: When pomegranates are multiplied through seeds, germination leads to vigorous tree growth. However, the tree will not be exactly similar to its parent and the resultant fruit produced will be irregular in colour, size, juiciness and sweetness. Methods: Soft-wood cuttings of Pomegranate cv. Bhagwa were planted in different growing media that were entitled G1- Soil + FYM, G2- Soil + Vermiculite, G3- Soil + Sand + FYM and G4- Soil + FYM + Vermiculite. These cuttings were treated with different combinations of 1-Naphthaleneacetic acid (NAA), Indole-3-butyric acid (IBA), Hydrogen peroxide (H2O2), Ascorbic acid (ASC) and Boric acid. Studies were carried out in a two-factorial randomized block design (FRBD) with 28 treatment permutations. Result: Current research indicated that treatment T18 (NAA 500 ppm + H2O2 30 ppm + IBA 500 ppm, Soil + Vermiculite (1:1) worked out to be the best treatment as it exhibited superiority over other treatments. The results of this experiment can practically be implemented to propagate quality planting material by adopting these best results/treatments.

Is calcium deficiency the real cause of bitter pit? A review.

Bitter pit is a disorder affecting the appearance of apples. Susceptibility is genetically controlled by both the cultivar and rootstock, with both environmental and horticultural factors affecting its severity and proportional incidence. Symptoms appear more frequently at the calyx end of the fruit and consist of circular necrotic spots, which take on a "corky" appearance visible through the peel. Bitter pit may develop before harvest, or after harvest, reducing the proportions of marketable fruit. In this review, current knowledge of the factors associated with the occurrence of bitter pit in apples is summarized and discussed along with their interactions with Ca uptake and distribution to fruit. This disorder has been previously linked with localized Ca deficiencies in fruit during its development. However, these relationships are not always clear. Even with over a century of research, the precise mechanisms involved in its development are still not fully understood. Additional factors also contribute to bitter pit development, like imbalances of mineral nutrients, low concentration of auxins, high concentration of gibberellins, changes in xylem functionality, or physiological responses to abiotic stress. Bitter pit remains a complex disorder with multiple factors contributing to its development including changes at whole plant and cellular scales. Apple growers must carefully navigate these complex interactions between genetics, environment, and management decisions to minimize bitter pit in susceptible cultivars. Accordingly, management of plant nutrition, fruit crop load, and tree vigor still stands as the most important contribution to reducing bitter pit development. Even so, there will be situations where the occurrence of bitter pit will be inevitable due to cultivar and/or abiotic stress conditions.

Guidelines for the choice of stone fruit rootstocks

Rootstocks for stone fruits (Prunus spp.) provide numerous and diverse production benefits, not least of which is the ability to produce high quality improved clonal fruit varieties, but also for better adaptation to orchard site variations and adoption of improved production techniques. These include mitigation of potential abiotic (soil, climate) and biotic (disease, pest) production limitations, as well as modification of natural tree vigor, precocity, and canopy architecture. Stone fruit production has lagged far behind that of apples with regard to rootstock-based control of vigor, which has contributed to comparatively less efficient production methods. Sweet cherries were the first stone fruits to have to a full range of vigor-controlling rootstocks become commercially available, about 25 years ago. It is primarily over the past decade that rootstocks conferring an increasing range of vigor control have begun to look promising for the larger-fruited stone fruits (peaches, apricots, plums), based on various scientific and commercial evaluation trials. This is likely to be a significant component of the overdue adoption of improved orchard training systems, particularly planar or “fruiting wall” canopies that are more labor efficient for pruning, fruit thinning, and harvest, and often contribute to better and/or more uniform fruit coloration, ripening, and quality. Such training systems also facilitate new and developing orchard data acquisition technologies and precision management techniques. General guidelines for the choice of stone fruit rootstocks for both specific growing conditions and anticipated contemporary production systems are discussed.

Windthrow causes declines in carbohydrate and phenolic concentrations and increased monoterpene emission in Norway spruce.

With the increasing frequencies of extreme weather events caused by climate change, the risk of forest damage from insect attacks grows. Storms and droughts can damage and weaken trees, reduce tree vigour and defence capacity and thus provide host trees that can be successfully attacked by damaging insects, as often observed in Norway spruce stands attacked by the Eurasian spruce bark beetle Ips typographus. Following storms, partially uprooted trees with grounded crowns suffer reduced water uptake and carbon assimilation, which may lower their vigour and decrease their ability to defend against insect attack. We conducted in situ measurements on windthrown and standing control trees to determine the concentrations of non-structural carbohydrates (NSCs), of phenolic defences and volatile monoterpene emissions. These are the main storage and defence compounds responsible for beetle´s pioneer success and host tree selection. Our results show that while sugar and phenolic concentrations of standing trees remained rather constant over a 4-month period, windthrown trees experienced a decrease of 78% and 37% of sugar and phenolic concentrations, respectively. This strong decline was especially pronounced for fructose (-83%) and glucose (-85%) and for taxifolin (-50.1%). Windthrown trees emitted 25 times greater monoterpene concentrations than standing trees, in particular alpha-pinene (23 times greater), beta-pinene (27 times greater) and 3-carene (90 times greater). We conclude that windthrown trees exhibited reduced resources of anti-herbivore and anti-pathogen defence compounds needed for the response to herbivore attack. The enhanced emission rates of volatile terpenes from windthrown trees may provide olfactory cues during bark beetle early swarming related to altered tree defences. Our results contribute to the knowledge of fallen trees vigour and their defence capacity during the first months after the wind-throw disturbance. Yet, the influence of different emission rates and profiles on bark beetle behaviour and host selection requires further investigation.

Assessing the Effectiveness of Pruning in an Olive Orchard Using a Drone and a Multispectral Camera: A Three-Year Study

The uses of precision oliviculture have increased in recent years to improve the quality and quantity of extra virgin olive oil. In traditional and intensive systems, biennial pruning is often applied to balance and maintain plant vigour, aiming at reducing management costs. This study presents the results of a three-year experiment with the objective of quantifying the effects of biennial pruning on the vegetative vigour of olive trees, investigating the geometric and spectral characteristics of each canopy determined with multispectral images acquired by UAV. The experiment was carried out in an olive orchard located in western Sicily (Italy). Multispectral images were acquired using a UAV in automatic flight configuration at an altitude of 70 m a.g.l. The segmentation and classification of the images were performed using Object-Based Image Analysis (OBIA) based on the Digital Elevation Model (DEM) and orthomosaic to extract the canopy area, height, volume and NDVI for each plant. This study showed that the technology and image analysis processing used were able to estimate vigour parameters at different canopy densities, compared to field measurements (R2 = 0.97 and 0.96 for canopy area and volume, respectively). Furthermore, it was possible to determine the amount of removed biomass for each plant and vigour level. Biennial pruning decreased the number of plants initially classified as LV (low-vigour) and maintained a vegetative balance for MV (medium-vigour) and HV (high-vigour) plants, reducing the spatial variability in the field.

Morphological and genetic characterization of jackfruit (Artocarpus heterophyllus) in the Kayunga and Luwero districts of Uganda

BackgroundJackfruit (Artocarpus heterophyllus) is an economically valuable fruit tree in Uganda. However, the production of jackfruit in Uganda is low. Additionally, because of deforestation, genetic erosion of the resource is predicted before its exploitation for crop improvement and conservation. As a prerequisite for crop improvement and conservation, 100 A. heterophyllus tree isolates from the Kayunga and Luwero districts in Uganda were characterized using 16 morphological and 10 microsatellite markers.ResultsThe results from the morphological analysis revealed variations in tree height, diameter at breast height (DBH), and crown diameter, with coefficient of variation (CV) values of 20%, 41%, and 33%, respectively. Apart from the pulp taste, variation was also observed in qualitative traits, including tree vigor, trunk surface, branching density, tree growth habit, crown shape, leaf blade shape, fruit shape, fruit surface, flake shape, flake color, flake flavor and pulp consistency/texture. Genotyping revealed that the number of alleles amplified per microsatellite locus ranged from 2 to 5, with an average of 2.90 and a total of 29. The mean observed (Ho) and expected (He) heterozygosity were 0.71 and 0.57, respectively. Analysis of molecular variance (AMOVA) indicated that 81% of the variation occurred within individual trees, 19% among trees within populations and 0% between the two populations. The gene flow (Nm) in the two populations was 88.72. The results from the ‘partitioning around medoids’ (PAM), principal coordinate analysis (PCoA) and genetic cluster analysis further revealed no differentiation of the jackfruit populations. The Mantel test revealed a negligible correlation between the morphological and genetic distances.ConclusionsBoth morphological and genetic analyses revealed variation in jackfruit within a single interbreeding population. This diversity can be exploited to establish breeding and conservation strategies to increase the production of jackfruit and hence boost farmers’ incomes. However, selecting germplasm based on morphology alone may be misleading.

Ecological Niche Studies on Hylurgus ligniperda and Its Co-Host Stem-Boring Insects

Hylurgus ligniperda (Fabricius), a significant quarantine pest, has recently invaded China, marking a new spread outside its known global distribution. This study aims to clarify the invasion and colonization mechanisms of H. ligniperda in Shandong Province, a primary colonization site. This study employed sampling surveys and analysis of damaged wood, discovering that the wood-boring insects sharing the same host as H. ligniperda mainly include Cryphalus sp., Arhopalus rusticus, and Shirahoshizo sp. Through ecological niche theory, the study analyzed the ecological niche relationships between H. ligniperda and these three wood-boring insects, from the perspectives of temporal and spatial resource utilization. The results reveal that these insects could cause damage to P. thunbergii trees at different health levels, with H. ligniperda being the most destructive. The ecological niches of insect populations varied significantly by tree vigor and height. Cryphalus sp. occupied the entire trunk, whereas A. rusticus and Shirahoshizo sp. were concentrated in the lower-middle trunk and the root section up to a depth of 1 m. Notably, H. ligniperda primarily targeted tree roots. Due to the differences in spatial distribution, there was no intense competition between H. ligniperda and other wood-boring insects. With a decline in the health of the host tree, Cryphalus sp. ascended the trunk, whereas H. ligniperda spread deeper into the roots and A. rusticus moved towards the base of the trunk and the top of the roots. Shirahoshizo sp. showed a less defined distribution pattern. Therefore, H. ligniperda was more dominant during the later stage of damage. The position occupied by each insect on the trunk was relatively stable, and the ecological niche overlap value with H. ligniperda was low in terms of temporal resources. Therefore, H. ligniperda and other stem-boring pests exhibit coexisting populations mainly through the allocation and utilization of spatial resources, eventually promoting the successful colonization of H. ligniperda.

Based on HPLC and HS-GC-IMS Techniques, the Changes in the Internal Chemical Components of Schisandra chinensis (Turcz.) Baill. Fruit at Different Harvesting Periods Were Analyzed.

Schisandra chinensis, as a traditional Chinese herbal medicine, has clear pharmacological effects such as treating asthma, protecting nerves and blood vessels, and having anti-inflammatory properties. Although the Schisandra chinensis fruit contain multiple active components, the lignans have been widely studied as the primary pharmacologically active compound. The volatile chemical components of Schisandra chinensis include a large amount of terpenes, which have been proven to have broad pharmacological activities. However, when to harvest to ensure the highest accumulation of pharmacologically active components in Schisandra chinensis fruits is a critical issue. The Schisandra chinensis fruit trees in the resource nursery were all planted in 2019 and began bearing fruit in 2021. Their nutritional status and tree vigor remain consistently good. The content of lignans and organic acids in the fruits of Schisandra chinensis over seven different harvest periods was tested, and the results of high-performance liquid chromatography (HPLC) indicated that the lignan content was higher, at 35 mg/g, in late July, and the organic acid content was higher, at 72.34 mg/g, in early September. If lignans and organic acids are to be selected as raw materials for pharmacological development, the harvest can be carried out at this stage. Using HS-GC-IMS technology, a total of 67 volatile flavor substances were detected, and the fingerprint of the volatile flavor substances in the different picking periods was established. It was shown by the results that the content of volatile flavor substances was the highest in early August, and 16 flavor substances were selected by odor activity value (OAV). The variable importance in projection (VIP) values of 16 substances were further screened, and terpinolene was identified as the key volatile flavor substance that caused the aroma characteristics of Schisandra chinensis fruit at different harvesting periods. If the aroma component content of Schisandra chinensis fruit is planned to be used as raw material for development and utilization, then early August, when the aroma component content is higher, should be chosen as the time for harvest. This study provides a theoretical basis for the suitable harvesting time of Schisandra chinensis for different uses, and promotes the high-quality development of the Schisandra chinensis industry.

Do Living Mulches or Environmental Conditions Have a Greater Impact on the External Quality of the Apple Fruit ‘Chopin’ Cultivar?

Research was carried out to assess the yield and quality of fruits from the new Polish apple tree ‘Chopin’—a ‘green peel’, scab-resistant cultivar under grass living mulch management. Blue fescue and red fescue were tested in experiment no. 1. In experiment no. 2, meadow grass and perennial ryegrass were used. Every species of grass was sown in two doses of 50 and 150 kg per ha. Herbicide fallow was introduced as a control in both experiments. Strongly variable temperatures and precipitations in the years of evaluation made it possible to estimate year—a function of variable environmental conditions—as an additional experimental factor. An unexpected effect of the presence of living mulch was its significant impact on the appearance of blush on the ‘green peel’ fruit. However, living mulches had little effect on weight and fruit size. Cool days during apple ripening enhanced the process of fruit skin red coloration. The effect of both agrotechnical and environmental factors on fruit quality was more visible in the case of less vigorous trees, which were more susceptible to experimental, stressful conditions. However, increasing the sowing dose of each grass seed did not influence red blushing, weight, or fruit size. An additional difficulty for the trees was the competition caused by the early germination of these living grass mulches, reinforced by the presence of Trifolium repens L.

Tree performances of eight rootstocks grafted with ‘Šumadinka’ sour cherry

Aim of study: This study was conducted to determine the suitability of seven clonal and one seedling rootstocks for grafting of sour cherry cv. ‘Šumadinka’ trough early tree growth, precocity, productivity and fruit quality. Aim of study: To evaluate the suitability of seven clonal rootstocks and one seedling rootstocks for grafting the sour cherry cv. ‘Šumadinka’ based on early tree development, precocity, productivity and fruit quality. Area of study: A sour cherry orchard in village Prislonica, Serbia, near Čačak city. Material and methods: The sour cherry cultivar ‘Šumadinka’ was grafted onto Colt, MaxMa 14, Krymsk 6, Adara, Cigančica, Gisela 5, Gisela 6 and Myrobalan rootstocks. Standard and validated procedures were used to measure tree growth, productivity (from 2017 to 2020), leaf area, fruit physical properties and fruit chemical composition (from 2019 to 2020). Main results: Significant differences were observed among rootstocks in leaf and petiole dimensions, leaf area, tree vigour, yield, fruit size, soluble solids content, titratable acidity, sugars and vitamin C contents, ripening and sweetness indexes. Trees grafted on Adara exhibited the highest tree vigour, while those on Gisela 6 produced the largest fruit size. On the other hand, Colt trees generally displayed the highest sugar content and sweetness index. Adara also showed improvements in fruit quality characteristics, whereas the properties associated with Myrobalan received the lowest evaluation scores. Research highlights: Adara rootstock demonstrated good adaptability to heavy and acidic soil conditions in Serbia, even though it was originally selected for cherry cultivation in heavy, waterlogged, and calcareous soils in Spain. This adaptability likely contributed to its higher vigour, yield, yield efficiency and good fruit quality.

Effects of tree vigor, competition and stand conditions on branch diameter for mixed plantations of Fraxinus mandshurica Rupr. and Larix olgensis Henry in Northeast China

Effects of tree vigor, competition and stand conditions on branch diameter for mixed plantations of Fraxinus mandshurica Rupr. and Larix olgensis Henry in Northeast China

Jujube as a Florida Fruit Crop

Despite being cultivated in China for millennia, the Chinese jujube is mostly unknown to Western consumers. The fruits are borne from vigorous trees that are tolerant to drought and other stresses, as well as disease. A number of cultivars have been demonstrated to produce in Florida. This publication is a review of jujube genetics and management as this crop gains favor among growers on small farms and home growers.