Tree Productivity Research Articles

Melatonin and Gibberellin Employing to Mitigate Heat Stress Effects on “Canino” Apricot

The fruit yield of apricot trees may decrease as a result of temperature stress. Through improving growth, productivity, and fruit quality, some compounds may play a significant part in resolving that issue. Therefore, this study was conducted during two successive growing seasons (2017 and 2018) in order to lessen the effects of heat stress on the production and fruit quality of Canino apricot trees cultivated on the farm of the Horticulture Research Station at El Kanater El Khayreia, Egypt, by foliar spray of hormonal substances and antioxidants i.e. (melatonin “MEL” or gibberellic acid” GA3 “each at concentration (25 mg/L) at pre-dormancy stage. It could be concluded that spraying Canino apricot trees at pre-dormancy stage (August) with both of GA3 and MEL enhanced the vegetative growth, as well as it improved flower quality compared with untreated control during the two cultivated seasons, also, melatonin improved growth and fruit set, yield, and fruit quality, followed by gibberellic acid compared with Control.

Effect of Tree Density on Yield and Fruit Quality of the Grafted Hazelnut Cultivar 'Tonda Francescana®'.

Optimizing planting density is crucial for balancing resource competition, light penetration, and tree productivity in orchard systems. This study investigateed the impact of planting density on the yield and fruit quality of the hazelnut cultivar 'Tonda Francescana®' grafted onto Corylus colurna L. rootstocks. The research aimed to assess how different planting densities influenced light penetration, canopy volume, yield, and the nutritional profile of hazelnuts during their sixth growing season. Three planting densities were tested: 625, 1250, and 2500 trees per hectare (low, medium, and high density, respectively). The results show that medium-density planting provided the best balance between light availability, canopy development, and yield efficiency. The synthesis of monounsaturated fatty acids (MUFA) and α-tocopherol (vitamin E) was more prominent in the medium-density system (80.2% and 10.3%, respectively), suggesting a favorable metabolic response to moderate competition for resources. In contrast, high-density planting yielded the most per hectare (2898 kg/ha) but exhibited lower individual tree productivity (1.16 kg). Low-density planting had the highest light penetration (53%) but lower overall yield (822 kg/ha) and quality, with greater starch accumulation in the fruit. In general, medium-density planting optimized both yield and kernel quality, with potential implications for orchard management and breeding strategies to enhance hazelnut production and nutritional value.

Examining stakeholder attitudes towards tree ecosystem services and disservices in urban environments: insights from Maharshi Dayanand University, Rohtak

ABSTRACT Urbanisation is a growing public health concern worldwide. Green spaces and trees provide critical ecosystem services in urban areas. The perceptions and attitudes of people regarding ecosystem services and disservices of trees were studied in one of the cleanest higher education institutions (HEIs) in India. Based on the Likert scale, this research focused on rating and preferences for ecosystem services and disservices from trees by different stakeholders. The study also aimed to understand the importance of socio-demographic variables on stakeholder’s perceptions towards ecosystem services and disservices. The study attempted to capture specific challenges and suggestions regarding tree management on campus. The survey included 367 people representing administrative staff, faculty members, residents and students from the Maharshi Dayanand University Campus (MDU), Rohtak (Haryana), India. Perceptions of different stakeholders were explored through a semi-structured questionnaire. Respondents rated oxygen (O2) production, medicinal potential and air pollution reduction services of trees as very important. They also highlighted some disservices of the trees on the university campus, such as problems with pollen allergy, litter, blocking of sunshine and monkey menace. Principal component analysis (PCA) identified eight significant varimax factors (VFs) for ecosystem services and disservices, explaining 59.59% of the variance in the data. Ordinal regression analysis indicated a strong correlation between residents on campus, educational background, marital status and ratings of ecosystem services and disservices. Respondents suggested organising more environmental sensitisation programmes, recruiting staff, ensuring strict compliance with rules and establishing tree clubs. The study concludes that people are highly dependent on campus trees, regard ecosystem services and are not significantly concerned about tree disservices. The findings of this study may motivate and guide universities and higher educational institutions across the globe to explore the perceptions of different stakeholders in understanding the ecological significance of trees for achieving their broad goals of campus sustainability.

Pear performance as affected by the application of some nano fertilizers in combination with biochar as a biostimulant under drought conditions

Drought is an environmental stress that can negatively influence growth and productivity of fruit trees because it decreases the photosynthetic rate and stomatal conductance and raises the rate of water loss from the plant surfaces. Therefore, this study investigated the soil application of biochar individually or in combination with the spraying of boron, silicon, and molybdenum relative to the growth attributes, fruit drop percentages, yield, and fruit quality of Le Conte pear trees grown under drought stress. The trees were fertilized by biochar at 0, 1, and 2 kg per tree individually or in combination with the foliar spraying with 0 mg B2O3 + 0 mg SiO2 + 0 mg MoO2, 10 mg B2O3 + 25 mg SiO2 + 25 mg MoO2, 20 mg B2O3 + 50 mg SiO2 + 50 mg MoO2 and 30 mg B2O3 + 75 mg SiO2 + 75 mg MoO2 at start of February, start of March and start of April, compared to untreated trees (control). The results showed that the soil addition of biochar or spraying of nano fertilizers individually or in combinations improved the vegetive growth, productivity and fruit quality, and leaf mineral content, meanwhile they reduced the fruit drop. The best results were obtained by the application of 2 kg biochar combined with 30 mg B2O3 + 75 mg SiO2 + 75 mg MoO2, which was superior to other applied treatments in the two seasons.

Climate change and exotic pathogens shift carbon allocation in Mediterranean mixed forests

Abstract Forecasting the effects of global change drivers on ecosystems is one of the most pressing challenges for scientists worldwide. Particularly, climate change and exotic pathogens might have a large impact on plant community dynamics and ecosystem functioning through changes in carbon uptake and sinks. Nevertheless, we still have a poor understanding of the combined effects of these two drivers on plant communities. Here, we explored the impact of rainfall reduction and exotic pathogens on the carbon balance of Mediterranean tree species. For this, we performed a 3‐year field experiment taking advantage of rainfall exclusion infrastructures (30% exclusion) installed in the southernmost European oak forests invaded by the aggressive exotic pathogen Phytophthora cinnamomi. We measured a set of 10 variables representative of tree carbon sources (photosynthetic rates) and sinks (primary production, reproduction, defence, and reserves) in adult trees of three species in two forest types: closed forests of Quercus suber and Q. canariensis, and open woodlands of Q. suber and Olea europaea. We found a large variability in the sensitivity of the different carbon sources and sinks to the effects of drought and pathogens, from variables highly sensitive to both factors (carbon fixation and reproduction, root chemistry) to variables only responsive to drought (litter production) or totally unresponsive (tree trunk, leaf chemistry). Although negative effects predominated, positive effects of rainfall exclusion were also detected in wet years, likely due to a reduction of pathogen abundance in drier soil. Trade‐offs between carbon sinks appeared in all tree species, but rainfall exclusion only modified trade‐offs in Q. suber, the species most susceptible to P. cinnamomi. Synthesis. We provide evidence on the complexity of the combined effects of abiotic (drought) and biotic (pathogens) global change drivers on carbon source and sinks of adult trees, including both negative direct effects and positive indirect effects. Our results showed that these effects varied among co‐existing species, particularly for carbon sinks directly related to tree demography (reproduction). Therefore, long‐term changes in the structure of Mediterranean mixed forests might be expected towards the dominance of species highly resistant to both drought and pathogens.

Comprehensive evaluation of using mineral and bio phosphorus fertilization on orange tree (Citrus sinensis) productivity

Phosphorus (P) is considered as an essential element in crop production. Besides, the study of P from the elemental and bio sources impacts on productivity and quality of orange trees could emphasize its utilization importance. This study aimed to evaluate the chemical implication of three treatments of P fertilization (Triple phosphate (TP; 620 and 900 g/tree/year), phosphate rock (PR; 1820 and 2742 g/tree/year) and 1:1 TP:PR on Valencia orange trees (Citrus sinensis L. Osbeckunder). Where, all these treatments were equipped with bio-phosphorus fertilizer (phosphorin) (0 and 5 g/tree/year added twice in the year, Feb. and Jun.). The measurements included leaves nitrogen (N), phosphorus (P) and Potassium (K), number of fruits (NoF), juice weight/volume, total soluble solids (T.S.S.), vitamin C (V.C), and acidity. The results showed that the treatment (50% TP +50% PR at 450+1371g/tree/year + phosphourin at 5g/tree/year) gave the highest values for all characters i.e. N % in tree leaves 2.61 and 2.69%, P% in tree leaves 0.16 and 0.17%, K in tree leaves 1.79 and 1.86%, number of fruits/tree 412.0 and 420.0, fruit weight 267.0 and 280.0g, fruit weight/tree 110.0 and 117.60kg, fruit size 260.41 and 272.37cm3, juice weight 114.1 and 126.15g, fruit juice 44.33 and 44.99%, juice volume 110.15 and 114.90cm3, peel thickness 0.58 and 0.60cm, T.S.S. 12.14 and 12.21%, T.S.S. / Acid ratio 9.07 and 9.41, and V.C 70.15 and 72.44 (mg/100 ml) as well as the lowest total acidity 0.93 and 0.91%, under both the 1st season and the 2nd one, respectively. In conclusions, as the application of bio-fertilization has improved the quality charcatistics over seasons. Thus, this study opens the way towards the advanced application of bio-P element to understand the biogeochemical cycles, dynamics and function of natural ecosystems elements in agricultural and food security program.

Temperature and leaf form drive contrasting sensitivity to nitrogen deposition across European forests

Raised emissions of biologically reactive nitrogen (N) have intensified N deposition, enhancing tree productivity globally. Nonetheless, the drivers of forest sensitivity to N deposition remain unknown. We used stem growth data from 62,000 trees across Europe combined with N deposition data to track the effects of air temperature and precipitation on tree growth's sensitivity to N deposition and how it varied depending on leaf form over the past 30 years. Overall, N deposition enhanced conifer growth (until 30 kg N ha−1 yr−1) while decreasing growth for broadleaved angiosperms. Lower temperatures led to higher growth sensitivity to N deposition in conifers potentially exacerbated by N limitation. In contrast, higher temperatures stimulated growth sensitivity to N deposition for broadleaves. Higher precipitation equally increased N deposition sensitivity in all leaf forms. We conclude that air temperature and leaf form are decisive in disentangling the effect of N deposition in European forests, which provides crucial information to better predict the contribution of N deposition to land carbon sink enhancement.

Enhanced fig tree production through endomycorrhizal fungi inoculation: A nursery study on tree cuttings derived from the Ifrane Region, Morocco

The mycorrhizal association represents a crucial symbiotic bond necessary for the vitality of the majority of plants. This report aims to investigate the impact of endomycorrhizal fungi on the production of fig trees from cuttings. The research took place in a nursery environment by inoculating fig cuttings sourced from three sites in Morocco with a composite inoculum of arbuscular mycorrhizal fungi (AMF). The mean root and vegetative masses of the inoculated plants after 140 days were 33.1 g and 35 g compared with 1.8 g and 6.4 g in the control. The mean shoot length and number of leaves developed from treated cutting were 98.5 cm and 17, respectively 29 cm and 4 leaves in control. Thus, the newly formed roots showed a well-established mycorrhizal colonization and contained different structures characteristic of arbuscular endomycorrhizae: arbuscules, vesicles, endophytes, hyphae and spores. The frequency and intensity of root mycorrhization were approximately 80% and 15.5%, respectively. The contents of arbuscules and vesicles were 2.5% and 5.5%. The study of formed spores showed a combination of 52 spores per 100 g of soil, belonging to 11 species and 3 genera: Glomus, Acaulospora and Rhizophagus with dominance of the genus Glomus (85%). Glomus macrocarpum and Glomus deserticola were the most abundant species, appearing at 30.77% and 19.23%, respectively. The results demonstrate a pronounced stimulating effect on both root formation and vegetative shoot development in the inoculated cuttings. Specifically, the early inoculation of fig cutting with the AMF inoculum significantly enhanced rhizogenesis end root system development. Consequently, the gradual establishment of mycorrhizal symbiosis at the root level of inoculated plants led to good development of the root mass and the vegetative mass. The inoculated plants showed good root and vegetative mass development due to the installation and the progressive development of mycorrhizal symbiosis at their roots.

Dry season irrigation promotes nutrient cycling by reorganizing Eucalyptus rhizosphere microbiome

In southern China, seasonal droughts and low soil phosphorus content constrain the productivity of Eucalyptus trees. To understand the rhizosphere microbiome response to the dry season, metagenomic sequencing analysis was used to investigate the 6-year-old Eucalyptus rhizosphere microbiome under four different irrigation and fertilization treatments. The results showed that irrigation and fertilization during the dry season significantly altered the composition of microbiome in the rhizosphere soil of Eucalyptus plantations. The soil physicochemical properties and enzyme activity explained 30.73 % and 29.75 % of the changes in bacterial and fungal community structure in Eucalyptus rhizosphere soil, respectively. Irrigation and fertilization during the dry season significantly altered the physicochemical properties of rhizosphere soil. Compared with the seasonal drought without fertilizer treatment (CK), the dry season irrigation with fertilizer treatment (WF) significantly increased the content of total nitrogen (46.34 %), available nitrogen (37.72 %), available phosphorus (440.9 %), and organic matter (35.34 %). Soil organic matter (OM), pH, and available phosphorus (AP) were key environmental factors influencing the microbial community composition. Moreover, irrigation and fertilization promoted carbon fixation and nitrogen and phosphorus mineralization, increasing soil OM content and the availability of inorganic nitrogen and phosphorus. Meanwhile, compared to the CK, the increase of acid phosphatase (16.81 %), invertase (146.89 %)and urease (59.45 %) in rhizosphere soil under irrigation (W) treatment further proves that dry season irrigation promote the soil carbon, nitrogen and phosphorus cycles. Irrigation and fertilization treatment alleviated the constraints of low phosphorus in southern China's soil, which promoted Eucalyptus productivity. In conclusion, we suggest implementing reasonable irrigation and fertilization strategies in the production practice of Eucalyptus and utilizing microbial resources to improve soil fertility and Eucalyptus productivity.

Assessing Larix principis-rupprechtii productivity and its determinants based on national forest inventory data in Hebei Province, China

Tree productivity is not only determined by stand structure, but also influenced by soil chemical properties, climate and topography. However, the relative importance of each indicator on larch (Larix principis-rupprechtii) productivity were uncertain. In this study, 76 pure larch forest plots were selected based on national forest inventory (NFI) data in Hebei Province, China. Structural equation model (SEM) was used to analyze the direct and indirect effects of stand structure, soil chemical properties, climate and topography on larch productivity, and to quantify the relative importance of each indicator in determining productivity. The results showed that stem volume growth (SVG) of larch was influenced by a combination of stand density, diameter at breast height (DBH), mean winter snow (PAS), annual temperature range (TD), slope, and alkali-hydrolysis nitrogen (AN). SVG tended to increase with decreasing stand density and AN content and increasing DBH. Stand density, DBH and AN were more important than PAS, TD, and slope in explaining SVG variation. The results can provide a scientific basis for adaptive management of larch forests.

The Effects of Planting Density, Training System and Cultivar on Vegetative Growth and Fruit Production in Young Mango (Mangifera indica L.) Trees

Increasing the planting density of mango orchards appears promising for obtaining higher yields, particularly during the first productive years. However, the challenge is to maintain a good balance between vegetative growth and fruit production in the longer term. The objective of this study was to decipher the effects of planting density, training system and cultivar on young mango trees’ growth and production. The experiment, conducted in North Queensland, consisted of five combinations of planting density and training system applied to the cultivars Keitt, Calypso and NMBP-1243. The planting densities were low (208 tree ha−1), medium (416 tree ha−1) and high (1250 tree ha−1). The closed vase conventional training system was applied at each density. Single leader and espalier on trellis training systems were applied at medium and high densities, respectively. The tree canopy dimensions were measured every 6 months from planting, and tree production was recorded from the third to the fifth years after planting. Vegetative growth and fruit production were the results of complex interactions between planting density, training system, cultivar and/or time. The expected increase in orchard yield with higher planting density was observed from the first productive year, despite lower individual tree production at high planting density. Lower vegetative growth and fruit production at high planting density were probably caused by competition between trees. NMBP-1243 and Keitt showed more rapid vegetative growth. Keitt was the most productive cultivar during the first three productive years. The detailed results of this study provide avenues to further explore the behaviour of mango trees at high planting densities.

Mathematical model for predicting the yield of apple trees on rootstock 62-396

Traditionally, forecasting apple tree yields was carried out on the basis of statistics of already obtained long-term yield dynamics or based on generative formations formed on the tree. The purpose of the work is to identify the most significant soil parameters for the formation of the apple tree varieties yield on the dwarf rootstock 62-396 and to build a mathematical model for predicting fruit yield in the conditions of the Central Chernozem region of the Russian Federation. Field research was carried out in 2004-2022 in industrial apple tree plantations at the age of full fruiting in the Lipetsk (two farms) and Tambov (eight farms) regions. Seven horticultural soil types have been studied. Based on statistical analysis, a mathematical model of apple tree productivity was obtained in the form of an analytical dependence on three factors. A geometric interpretation of the regression model is given using the Mathcad symbolic mathematics system in the form of response surfaces and the corresponding level lines. Practical recommendations are given for choosing rational parameters within selected intervals of factor variation.

Phosphorus limitation promotes soil carbon storage in a boreal forest exposed to long‐term nitrogen fertilization

AbstractForests play a crucial role in global carbon cycling by absorbing and storing significant amounts of atmospheric carbon dioxide. Although boreal forests contribute to approximately 45% of the total forest carbon sink, tree growth and soil carbon sequestration are constrained by nutrient availability. Here, we examine if long‐term nutrient input enhances tree productivity and whether this leads to carbon storage or whether stimulated microbial decomposition of organic matter limits soil carbon accumulation. Over six decades, nitrogen, phosphorus, and calcium were supplied to a Pinus sylvestris‐dominated boreal forest. We found that nitrogen fertilization alone or together with calcium and/or phosphorus increased tree biomass production by 50% and soil carbon sequestration by 65% compared to unfertilized plots. However, the nonlinear relationship observed between tree productivity and soil carbon stock across treatments suggests microbial regulation. When phosphorus was co‐applied with nitrogen, it acidified the soil, increased fungal biomass, altered microbial community composition, and enhanced biopolymer degradation capabilities. While no evidence of competition between ectomycorrhizal and saprotrophic fungi has been observed, key functional groups with the potential to reduce carbon stocks were identified. In contrast, when nitrogen was added without phosphorus, it increased soil carbon sequestration because microbial activity was likely limited by phosphorus availability. In conclusion, the addition of nitrogen to boreal forests may contribute to global warming mitigation, but this effect is context dependent.

Evaluation of the Effect of Soil Water Conditions on the Development and Water Requirements of Adult Oil Palm (Elaeis guineensis Jacq.) in the Northern Region of Colombia

Sustainable water management is a key approach for enhancing the productivity of oil palm trees while addressing the impacts of climate change and variability. Determining the water needs of a crop is crucial for the appropriate application of water. This research was carried out in two plantations in Agustín Codazzi, Colombia, using a completely randomized design. This study involved examining the impacts of five different water conditions (50, 150, 300, 450, and 600 L per day) on the growth and yields of mature oil palm trees (aged 10–17 years), and their water consumption was calculated using the water balance method. The results indicated that the crop was negatively affected by daily water applications of 300, 150, and 50 L per day, showing statistically significant differences (p < 0.05) when compared to the 450 and 600 L per day treatments, particularly in terms of leaf emergence, leaf area index, and yield (tons per hectare). The 50 L per day treatment resulted in the most substantial decrease in yield (around 26%), primarily attributed to a reduction in the number of bunches. The most favorable crop responses were observed with water applications of 450 and 600 L per day, aligning with the crop’s potential evapotranspiration values (ranging between 5.4 and 5.7 mm per day) and yielding crop coefficients of 0.88 and 0.9, respectively. Notably, these values varied between dry and rainy seasons, peaking between December and March.

Effects of Water and Nitrogen Regulation on Apple Tree Growth, Yield, Quality, and Their Water and Nitrogen Utilization Efficiency.

Apple tree productivity is influenced by the quantity of water and nutrients that are supplied during planting. To enhance resource utilization efficiency and optimize yields, a suitable strategy for supplying water and nitrogen must be established. A field experiment was conducted using a randomized block group design on five-year-old apple trees in Ningxia, with two irrigation lower limit levels (55%FC (W1) and 75%FC (W2)) and four N application levels (0 (N1), 120 (N2), 240 (N3), and 360 (N4) kg·ha-1). Our findings showed that leaf N content increased with a higher irrigation lower limit, but the difference was not statistically significant. However, the leaf N content significantly increased with increasing N application. The growth pattern of new shoots followed logistic curve characteristics, with the maximum new shoot growth rate and time of new shoot growth being delayed under high water and high nitrogen treatments. Apple yield and yield components (weight per fruit and number of fruits per plant) were enhanced under N application compared to no N application. The maximum apple yields were 19,405.3 kg·ha-1 (2022) and 29,607 kg·ha-1 (2023) at the N3 level. A parabolic relationship was observed between apple yield and N application level, with the optimal range of N application being 230-260 kg⸱ha-1. Apple quality indicators were not significantly affected by the irrigation lower limit but were significantly influenced by N application levels. The lower limit of irrigation did not have a significant impact on the quality indicators of the apples. Water and N utilization efficiencies improved with the W2 treatment at the same N application level. A negative relationship was observed between the amount of nitrogen applied and the biased productivity of nitrogen fertilizer. The utilization of nitrogen fertilizer was 127.6 kg·kg-1 (2022) and 200.3 kg·kg-1 (2023) in the W2N2 treatment. The apple yield was sustained, the quality of the fruit improved, and a substantial increase in water productivity was achieved with the W2N3 treatment. The findings of this study can be used as a reference for accurate field irrigation.

Modeling the Transmission Dynamics and Optimal Control Strategy for Huanglongbing

Huanglongbing (HLB), also known as citrus greening disease, represents a severe and imminent threat to the global citrus industry. With no complete cure currently available, effective control strategies are crucial. This article presents a transmission model of HLB, both with and without nutrient injection, to explore methods for controlling disease spread. By calculating the basic reproduction number (R0) and analyzing threshold dynamics, we demonstrate that the system remains globally stable when R0<1, but persists when R0>1. Sensitivity analyses reveal factors that significantly impact HLB spread on both global and local scales. We also propose a comprehensive optimal control model using the pontryagin minimum principle and validate its feasibility through numerical simulations. Results show that while removing infected trees and spraying insecticides can significantly reduce disease spread, a combination of measures, including the production of disease-free budwood and nursery trees, nutrient solution injection, removal of infected trees, and insecticide application, provides superior control and meets the desired control targets. These findings offer valuable insights for policymakers in understanding and managing HLB outbreaks.

Simulated fire injury: effects of trunk girdling and partial defoliation on reproductive development of apple trees (Malus domestica)

Fire damage can significantly impact fruit productivity in orchards. However, the effects of nonlethal fire injuries on the reproductive development of apple trees remain poorly understood. To investigate these effects, we implemented three treatments: trunk girdling to simulate fire injury to xylem, defoliation of a third of the canopy (simulated crown fire injury), and a combined treatment (simulated surface fire injury), alongside a control. The experiment was conducted during the 2021–22 growing season using a randomised block design with four biological replicate plots. Girdling was less effective than crown and surface fire treatments in influencing fruit composition during the current growing season, and flowering and fruiting in the following season. The crown and surface fire treatments induced localised detrimental effects on fruit sugar and titratable acidity while stimulating peel blush. Additionally, these treatments led to reduced starch reserves by harvest, which likely disrupted subsequent flowering and crop load near the previously defoliated sections of the canopy. When surface fires damage leaves near the base of the canopy in addition to the trunk, fruit production in the lower part of the canopy is more likely to be compromised in the following season. Crown fires, which cause leaf loss near the apex of the canopy, appear to be particularly detrimental to tree productivity, as the top defoliation treatment impaired carbohydrate reserves in shoot terminals and roots. In conclusion, fire-induced loss of leaf area during fruit growth alters fruit composition in the current growing season and may lead to lower yields in the subsequent season.

Ecofriendly treatments to improve pomegranate trees production and tolerance to climate change

BackgroundPomegranate is capable of growing in different agro-climatic conditions ranging from tropical to sub-tropical. Where vegetative growth, nutritional and physiological status of pomegranate plants oscillate at high temperatures waves in the summer season. While we can overcome the cracking and sunburn of fruits, which are the main problems confronting pomegranate cultivars due to their significant impact on the quality of fruits.MethodsThe present research was conducted over the course of two consecutive seasons in 2021 and 2022. The study focused on ten-year-old trees that were cultivated in sandy soil inside a private orchard situated 70 km away from Cairo on the Cairo-Alexandria desert road in Egypt (30o13′31.4″N30o39′09″E). The aim of the present work was to evaluate the effect of foliar spraying of Wonderful pomegranate trees with some nutrients (B, Zn, Fe, Mn, Ca and Cu), amino acids and irradiated licorice on vegetative growth, fruit physical, quality and chemical and leaf chemical parameters. A randomized full-block design with three duplicates was employed in the study. Using the recently computed least significant difference values at the 5% level, averages were compared.ResultsThe results indicated that foliar spraying with nutrients, amino acids and licorice extract (irradiated or not) alone or in combination significantly increased the vegetative growth and leaf total chlorophyll content compared to the control. Also, they significantly increased fruit length, diameter, weight, and number/tree and thus yield. As compared to the control, all treatments significantly reduced the number of sunburned and cracked fruits leading to decrease the percentage of un-marketable fruits. The juice content of anthocyanin, total sugars and total soluble solids increased significantly in response to all treatments compared to the control while the acidity% greatly reduced. When these treatments were used instead of the control, the content of N, P, K, Fe, Zn, and Mn in the leaves was also positively increased.ConclusionsIn conclusion, foliar spraying of “Wonderful” pomegranate trees with a mixture of nutrients (B, Zn, Fe, Mn, Ca, Cu) and amino acids or irradiated licorice extract can be considered as a suitable management of the problem of sunburned or cracked fruits while improving the physical and chemical fruit quality with increased productivity.

Important accumulated mercury pool in a remote alpine forest and dynamic accumulation revealed by tree rings in China's Qilian Mountains

Quantification mercury (Hg) pools in forests is crucial for understanding the Hg assimilation, flux and even biogeochemical cycle in forest ecosystems. While several investigations focused on Hg pools among broad-leaved, coniferous and mixed forests, there was still absent information on alpine forest. We sampled soil, moss and various tissues of the dominant Qinghai spruce (Picea crassifolia Kom.) to investigate Hg concentrations and pools, and assess Hg accumulation dynamics in the Qilian Mountains, northwestern China. The mean Hg concentration increased in the following order: trunk wood (1.8 ± 0.7 ng g−1) < branch (4.6 ± 0.8 ng g−1) < root (12.2 ± 2.9 ng g−1) < needle (19.3 ± 5.6 ng g−1) < bark (28.7 ± 9.0 ng g−1) < soil (34.1 ± 7.7 ng g−1) < litterfall (42.9 ± 2.9 ng g−1) < moss (62.5 ± 5.0 ng g−1). The soil contained Hg pools two orders of magnitude higher than vegetation and accounted for 92.2 % of the total Hg pool in the alpine forest ecosystem. Moss, despite representing only 2.7 % of total vegetation biomass, contained a disproportionate 16.7 % of the Hg pool. Although species-specific, aboveground spruce tissues exhibited higher Hg pools in alpine forests compared to other forests in China and America. The dynamic accumulation indicated that increasing atmospheric Hg concentration and enhancing tree productivity contributed to rising Hg assimilation in remote alpine forests, particularly after the 1960s. Our results highlight the relatively high levels of Hg pools in aboveground tree tissues of alpine forest and reveal a significant increase in Hg accumulation. We recommend that when assessing Hg dynamics in forest ecosystems, it is crucial to consider both the variability in atmospheric Hg exposure levels and the forest productivity.

Physiological and molecular responses of 'Hamlin' sweet orange trees expressing the VvmybA1 gene under cold stress conditions.

Overexpression of VvmybA1 transcription factor in 'Hamlin' citrus enhances cold tolerance by increasing anthocyanin accumulation. This results in improved ROS scavenging, altered gene expression, and stomatal regulation, highlighting anthocyanins' essential role in citrus cold acclimation. Cold stress is a significant threat to citrus cultivation, impacting tree health and productivity. Anthocyanins are known for their role as pigments and have emerged as key mediators of plant defense mechanisms against environmental stressors. This study investigated the potential of anthocyanin overexpression regulated by grape (Vitis vinifera) VvmybA1 transcription factor to enhance cold stress tolerance in citrus trees. Transgenic 'Hamlin' citrus trees overexpressing VvmybA1 were exposed to a 30-day cold stress period at 4°C along with the control wild-type trees. Our findings reveal that anthocyanin accumulation significantly influences chlorophyll content and their fluorescence parameters, affecting leaf responses to cold stress. Additionally, we recorded enhanced ROS scavenging capacity and distinct expression patterns of key transcription factors and antioxidant-related genes inthe transgenic leaves. Furthermore, VvmybA1 overexpression affected stomatal aperture regulation by moderating ABA biosynthesis, resulting in differential responses in a stomatal opening between transgenic and wild-type trees under cold stress. Transgenic trees exhibited reduced hydrogen peroxide levels, enhanced flavonoids, radical scavenging activity, and altered phytohormonal profiles. These findings highlighted the role of VvmybA1-mediated anthocyanin accumulation in enhancing cold tolerance. The current study alsounderlines the potential of anthocyanin overexpression as a critical regulator of the cold acclimation process by scavenging ROS in plant tissues.