Physiological Fruit Research Articles

Melatonin Use in Post-harvest Fruit Physiology: Effect of Melatonin Treatments on Quality Properties, Primer and Seconder Metabolites Contents of Hawthorn Fruit During Cold Storage

Melatonin Use in Post-harvest Fruit Physiology: Effect of Melatonin Treatments on Quality Properties, Primer and Seconder Metabolites Contents of Hawthorn Fruit During Cold Storage

Impact of Dropping on Postharvest Physiology of Tomato Fruits Harvested at Green and Red Ripeness Stages.

Dropping during transportation is a critical issue for tomato fruits, as it triggers ethylene production and affects quality parameters, leading to lower quality and a reduced storage life. Thus, this study was conducted to assess the physiological alterations in tomato fruits subjected to dropping. This study involved tomatoes harvested at green and red stages, subjected to the following five dropping treatments: 0 cm, 10 cm, 30 cm, 50 cm, and 100 cm. The results revealed that dropping from 100 cm induced the highest ethylene production, particularly in green fruits, where production began within one hour and peaked within 48 h. Red fruits exhibited a dose-dependent response to mechanical stress, with a notable decrease in ethylene production starting from the second week post-dropping, suggesting a regulatory mechanism. CO2 production peaked at 350.1 µL g-1 h-1 in green fruits and 338.2 µL g-1 h-1 in red fruits one day after dropping from 100 cm. Dropping also significantly influenced fruit color, firmness, electrolyte leakage, and vitamin C content. Principal component analysis (PCA) revealed distinct changes in metabolite profiles, with methionine and ACC (1-aminocyclopropane-1-carboxylate), key ethylene precursors, increasing in response to dropping, particularly in red fruits. These findings underscore the critical role of mechanical stress in modulating fruit physiology, with implications for post-harvest handling practices aimed at enhancing fruit quality and shelf life.

Effect of different timing of water deficit combined with foliar application of ascorbic acid on physiological variables of sour passion fruit

The objective of this study was to evaluate the effects of deficit irrigation treatments during different phenological stages and foliar application of ascorbic acid on gas exchange, photosynthetic pigments, chlorophyll fluorescence, electrolyte leakage, relative water content and yield of ‘BRS GA1’ sour passion fruit. Treatments were distributed in randomized blocks, in a split-plot scheme, with plots consisting of six deficit irrigation treatments, based on crop evapotranspiration – ETc (irrigation with 100% ETc - FULL; irrigation with 50% ETc in the vegetative stage - VEG; flowering stage - FLO; fruiting stage - FRU; successively in the vegetative/flowering stages - VEG + FLO and vegetative/fruiting stages - VEG + FRU) and subplots represented by three concentrations of ascorbic acid - AsA (0, 0.5 and 1.0 mM). Water deficit induces changes in photosynthetic activity across all developmental stages of sour passion fruit, resulting in reduced yield in the period of 160 and 200 days after transplanting. Notably, flowering exhibits the greatest physiological acclimatization to water deficit conditions, albeit with more pronounced losses in the yield. When water deficit occurs during the vegetative and fruiting stages and is coupled with foliar application of ascorbic acid at 0.5 mM, there is an enhancement in the synthesis of photosynthetic pigments in ‘BRS GA1’ sour passion fruit. Overall, foliar application of ascorbic acid at concentrations of 0.5 and 1.0 mM emerges as a viable strategy to mitigate the adverse effects of water deficit on the physiology and yield of sour passion fruit at 200 days after transplanting.

Advances in strawberry postharvest preservation and packaging: A comprehensive review.

Strawberries spoil rapidly after harvest due to factors such as the ripening process, weight loss, and, most importantly, microbial contamination. Traditionally, several methods are used to preserve strawberries after harvest and extend their shelf life, including thermal, plasma, radiation, chemical, and biological treatments. Although these methods are effective, they are a concern from the perspective of safety and consumer acceptance of the treated food. To address these issues, more advanced environment-friendly technologies have been developed over the past decades, including modified and controlled atmosphere packaging, active biopolymer-based packaging, or edible coating formulations. This method can not only significantly extend the shelf life of fruit but also solve safety concerns. Some studies have shown that combining two or more of these technologies can significantly extend the shelf life of strawberries, which could significantly contribute to expanding the global supply chain for delicious fruit. Despite the large number of studies underway in this field of research, no systematic review has been published discussing these advances. This review aims to cover important information about postharvest physiology, decay factors, and preservation methods of strawberry fruits. It is a pioneering work that integrates, relates, and discusses all information on the postharvest fate and handling of strawberries in one place. Additionally, commercially used techniques were discussed to provide insight into current developments in strawberry preservation and suggest future research directions in this field of study. This review aims to enrich the knowledge of academic and industrial researchers, scientists, and students on trends and developments in postharvest preservation and packaging of strawberry fruits.

Physiological and transcriptomic analyses provide new insights into the regulatory mechanisms of accelerated senescence of litchi fruit in response to strigolactones

Strigolactones (SLs), a class of plant hormones that are derived from carotenoid metabolism, play pivotal roles in regulating various physiological processes in plants. However, the action mode of SLs in regulating postharvest physiology of fruits is not well understood. This study aimed to explore the effect of exogenous GR24 (a synthetic analogue of SLs) on litchi senescence and its possible mechanisms based on physiological and transcriptomic analyses. The results demonstrated that GR24 treatment at 0.5 μM accelerated the development of pericarp browning and discoloration in litchi fruit during storage at ambient conditions, which was related to exacerbated oxidative stress and aggravated membrane deterioration, as indicated by increased reactive oxygen species production, membrane permeability and malondialdehyde content. Compared to those in the control fruit, lower activities of antioxidant enzyme (superoxide dismutase, catalase, glutathione reductase, ascorbate peroxidase and glutathione peroxidase) and contents of antioxidants (ascorbic acid and reduced glutathione), but higher prooxidant enzyme (peroxidase) activity were observed in GR24-treated fruit. Transcriptomic analysis revealed that GR-24 treatment downregulated the expression of genes associated with antioxidant system, pentose phosphate pathway, oxidative phosphorylation and energy metabolism, which was aligned with the physiological results. These findings provide insights into the role of SLs in regulating senescence of harvested litchi fruit.

Sweet Cherry Fruit Firmness Evaluation Using Compression Distance Methods

Flesh firmness in sweet cherries is determined using the measurement of normalized deformation force, i.e., determining the required force for a distance equal to 5 or 10% of the diameter of the cherries per millimeter. However, a firmness method involving a defined distance is quite simple and suitable for easy applications. Hence, our study focuses on the impact of fruit physiology under various and fixed distances. To assess the firmness evaluation, two sweet cherry cultivars (Canada Giant and Regina) were selected and subjected to three different levels of compression distance equal to 1%, 5%, 10% of the fruit’s small thickness dimension along with a consistent compression distance of 0.16 mm. There was a strong correlation between panelists’ preferences and the fruit that had been subjected to both a 1% deformation force and a fixed distance of 0.16 mm within each cultivar. Physiological traits, membrane integrity, and the metabolome of the fruit in these categories were mostly unaffected by the control (0%), or 1%, deformation force, as shown by clustering and PCA analysis. The control and 1% deformation force groups showed similar patterns, contrary to those of the 5% and 10% deformation force groups. Given these considerations, a fixed distance of 0.16 mm and a minimal 1% deformation force possess the potential to be employed and implemented for monitoring the firmness of sweet cherries during postharvest preservation.

Cuticle properties, wax composition, and crystal morphology of Hami melon cultivars (Cucumis melo L.) with differential resistance to fruit softening

Cuticle wax chemicals are cultivar-dependent and contribute to storage quality. Few research reported on wax analysis between melting flesh-type (MF; ‘Jinhuami 25’) and nonmelting flesh-type (NMF; ‘Xizhoumi 17’ and ‘Chougua’) Hami melons. Chemicals and crystal structures of Hami melon cuticular wax, cell wall metabolism related to fruit melting, and fruit physiology were analyzed to observe wax functions. Results showed that Hami melon cuticle wax predominantly consists of esters, alkanes, alcohols, aldehydes, and terpenoids. MF-type has a lower alkane/terpenoid ratio, concomitant to its higher weight loss and cuticle permeability. Micromorphology of wax crystals appears as numerous platelets with irregular crystals, and the transformation of wax structure in NMF Hami melon is delayed. Waxy components affect cell wall metabolism and physiological quality, which results in the pulp texture difference between MF-type and NMF-type during storage. Results provide a reference for the regulation of wax synthesis in both types of melons.

Characterization of leucine aminopeptidase (LAP) activity in sweet pepper fruits during ripening and its inhibition by nitration and reducing events

Key messagePepper fruits contain two leucine aminopeptidase (LAP) genes which are differentially modulated during ripening and by nitric oxide. The LAP activity increases during ripening but is negatively modulated by nitration.Leucine aminopeptidase (LAP) is an essential metalloenzyme that cleaves N-terminal leucine residues from proteins but also metabolizes dipeptides and tripeptides. LAPs play a fundamental role in cell protein turnover and participate in physiological processes such as defense mechanisms against biotic and abiotic stresses, but little is known about their involvement in fruit physiology. This study aims to identify and characterize genes encoding LAP and evaluate their role during the ripening of pepper (Capsicum annuum L.) fruits and under a nitric oxide (NO)-enriched environment. Using a data-mining approach of the pepper plant genome and fruit transcriptome (RNA-seq), two LAP genes, designated CaLAP1 and CaLAP2, were identified. The time course expression analysis of these genes during different fruit ripening stages showed that whereas CaLAP1 decreased, CaLAP2 was upregulated. However, under an exogenous NO treatment of fruits, both genes were downregulated. On the contrary, it was shown that during fruit ripening LAP activity increased by 81%. An in vitro assay of the LAP activity in the presence of different modulating compounds including peroxynitrite (ONOO−), NO donors (S-nitrosoglutathione and nitrosocyteine), reducing agents such as reduced glutathione (GSH), l-cysteine (l-Cys), and cyanide triggered a differential response. Thus, peroxynitrite and reducing compounds provoked around 50% inhibition of the LAP activity in green immature fruits, whereas cyanide upregulated it 1.5 folds. To our knowledge, this is the first characterization of LAP in pepper fruits as well as of its regulation by diverse modulating compounds. Based on the capacity of LAP to metabolize dipeptides and tripeptides, it could be hypothesized that the LAP might be involved in the GSH recycling during the ripening process.

Tissue-specific proteome profile analysis reveals regulatory and stress responsive networks in passion fruit during storage

Passiflora edulis, commonly known as passion fruit, is a crop with a fragrant aroma and refreshingly tropical flavor that is a valuable source of antioxidants. It offers a unique opportunity for growers because of its adaptability to tropical and subtropical climates. Passion fruit can be sold in the fresh market or used in value-added products, but its postharvest shelf life has not been well-researched, nor have superior cultivars been well-developed. Understanding the proteins expressed at the tissue level during the postharvest stage can help improve fruit quality and extend shelf life. In this study, we carried out comparative proteomics analysis on four passion fruit tissues, the epicarp, mesocarp, endocarp, and pulp, using multiplexed isobaric tandem mass tag (TMT) labeling quantitation. A total of 3352 proteins were identified, including 295 differentially expressed proteins (DEPs). Of these DEPs, 213 showed a fold increase greater than 1.45 (50 proteins) or a fold decrease less than 0.45 (163 proteins) with different patterns among tissue types. Among the DEPs, there were proteins expressed with functions in oxygen scavenging, lipid peroxidation, response to heat stress, and pathogen resistance. Thirty-six proteins were designated as hypothetical proteins were characterized for potential functions in immunity, cell structure, homeostasis, stress response, protein metabolism and miraculin biosynthesis. This research provides insight into tissue-specific pathways that can be further studied within fruit physiology and postharvest shelf life to aid in implementing effective plant breeding programs. Knowing the tissue-specific function of fruit is essential for improving fruit quality, developing new varieties, identifying health benefits, and optimizing processing techniques.

Influence of Staggered Hexanal Treatment on Post-Storage Fruit Physiology, Functional Quality and Enzyme Activity of ‘Royal Delicious’ Apple

Influence of Staggered Hexanal Treatment on Post-Storage Fruit Physiology, Functional Quality and Enzyme Activity of ‘Royal Delicious’ Apple

A model integrating fruit physiology, perforation, and scavenger for prediction of ethylene accumulation in fruit package

The modelling of headspace atmosphere (O2, CO2), relative humidity, condensation, and shelf life of packaged fresh produce has been extensively reported. However, there has been a lack of effort in modelling ethylene (C2H4) accumulation within the packaging or storage environment. This study aimed to address this significant research gap by developing a model for the prediction of C2H4 accumulation within fruit package. This model integrated fruit physiology, gas transmission through perforation, and C2H4 removal by a scavenger made up of KMnO4. The experimental validation was conducted using packaged avocados, encompassing various storage conditions, package (perforation), scavenger, and fruit parameters. The use of perforation effectively maintained C2H4 accumulation below 2 µL L−1 in the avocado package for 12 days within the temperature range of 5 to 25ºC. Moreover, the scavenger successfully kept C2H4 accumulation below 1 µL L−1 within just 8 h for all experimental conditions. The scavenger demonstrated a higher efficacy in C2H4 removal compared to perforation, achieving a complete removal. The level of accuracy through statistical parameters underscores the acceptability and reliability of the model in predicting C2H4 accumulation in fruit package. The model was used to optimize the perforation size according to the required equilibrium O2 and C2H4 accumulation in the avocado package.

Light in post-harvest physiology of juicy fruits

Light in post-harvest physiology of juicy fruits

Disrupted sugar transport and continued sugar consumption lead to sugar decline in ripe ‘Shixia’ longan fruit

Longan fruit pulp sugar content and sweetness decline after ripening, which affects fruit quality and postharvest storage. Fruit sugar decline research has focused mainly on fruit physiology and biochemistry. To explore the molecular mechanism underlying sugar decline, we conducted transcriptome and metabolome analyses of ‘Shixia’ longan fruit aril (pulp) tissues at different stages of development. In total, 873 metabolites and 26584 annotated unigenes were identified. Sugar content changes in aril tissues were closely related to gene expression patterns related to starch and sucrose metabolism, such as sucrose phosphate synthase (SPS), invertase (INV), sucrose synthase (SUS), and glucose-6-phosphate isomerase (GPI). Notably, glycolytic pathway gene expression and cellulose and lignin contents increased during the sugar decline stage compared to the sugar accumulation stage. Conversely, sucrose transporter genes, such as DlSWEET2b, DlSWEET10, and DlSWEET12, showed the opposite expression pattern, pointing to reduced sucrose transport during sugar decline. These results indicate that longan fruit sugar decline is likely related to an interruption of sugar input (cessation of sucrose transport to the aril) and continued glycolysis and cellulose/lignin biosynthesis. This provides a new way to delay longan fruit sugar decline, by regulating sugar transport instead of inhibiting respiration.

Enhancement of antioxidant quality by Bacillus siamensis N-1 and the role of LcPOD4 in regulating peel browning and senescence of litchi fruit

Plant peroxidases (POD) are involved in various physiological and biochemical processes. Currently, there are relatively few studies on the role of POD in regulating the antioxidant capacity and senescence of postharvest litchi. In this study, we assessed the effects of Bacillus siamensis strain N-1 on the physiology and antioxidant quality of litchi fruit stored at 25 ℃, and characterized the molecular function of LcPOD4 gene in regulating the senescence of litchi fruit. The results showed that N-1 treatment significantly suppressed the increase in ethylene production, electrolyte leakage, and malondialdehyde (MDA) but did not inhibit the respiration rate of litchi during storage. Meanwhile, N-1-treated fruit maintained higher levels of phenolics, flavonoids, and total antioxidant capacity (T-AOC) and lower levels of superoxide anions (O2-.) and hydrogen peroxide (H2O2). In addition, N-1 treatment enhanced the activity of defense enzymes, including superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), and phenylalanine ammonia-lyase (PAL). The results of quantitative real-time PCR (qRT-PCR) showed that the expression of nine selected LcPOD genes was induced by N-1 treatment at later stages of litchi storage. LcPOD4 cloned from litchi fruit was located in the cell wall and membrane. Transient overexpression of the LcPOD4 gene in tomato and litchi fruits significantly enhanced POD activity and total phenolic and flavonoid contents while accelerating peel color change in the fruit. Collectively, our results indicate that LcPOD4 may contribute, at least partially, to the enhancement of antioxidant capacity in litchi fruit but does not retard peel browning and senescence.

Limes physiological fruit drop extracts were incorporated into active packaging film for strawberry preservation

SummaryThe comprehensive utilisation of food waste has become a global development demand for enhancing their added value. This study aimed to develop and utilise physiological fruit drop of Citrus aurantium L. var Daidai with rich phenolic acids and flavonoids. Therefore, different concentrations (1%, 3%, 5%, 10% wt, based on pullulan weight) of daidai physiological fruit drop extracts (DE) were incorporated into pullulan/bacterial cellulose (BC) packaging film (PB2‐DE). The effects of different concentrations of DE on composite films were comprehensively evaluated. It was found that the mechanical properties, ultraviolet barrier properties, and antioxidant properties of the films were improved with the addition of DE. Moreover, application tests have verified that films containing DE can effectively maintain the attractive quality of strawberries. Conclusively, the results demonstrated the feasibility of DE incorporation into films to increase the value of the waste and the potential applicability of films containing DE in strawberry preservation.

Early diagnosis and mechanistic understanding of citrus Huanglongbing via sun-induced chlorophyll fluorescence

Citrus Huanglongbing (HLB) is a serious disease that is devastating the citrus industry worldwide. The infection of HLB causes a significant impact on the photosynthesis and growth of citrus but the early diagnosis of HLB is challenging. This study aims to propose an effective method for early HLB diagnosis and mechanistic understanding via sun-induced chlorophyll fluorescence (SIF) during the whole growth period of citrus. SIF signals and net photosynthetic rate (A) of healthy, asymptomatic HLB (aHLB) and symptomatic HLB (sHLB) citrus leaf samples were acquired throughout the whole citrus growth period. Seasonal variations of the peak SIF yield at 687 nm (SIFY687) and 741 nm (SIFY741) and A were investigated. Leaf chlorophyll a content (Ca), chlorophyll b content (Cb), and carotenoids content (Cxc) were also measured by spectrophotometry in the laboratory. It was found that the A of the aHLB was close to that of sHLB, which was significantly different from the healthy leaves at the physiological fruit dropping (PFD) period. The ratio of chlorophyll content (Chl) to Cxc (Chl/Cxc) was evidently different between aHLB and healthy leaves at the late PFD and early fruit expanding (FE) stage, which could be a potential biomarker to identify HLB in the incubation period. The classification result showed PFD was the optimal stage for HLB diagnosis and the index based on SIFY741 was recommended (overall accuracy > 90 %). Moreover, HLB had a great influence on the relationship between A and SIF at the PFD stage, and the coefficients of determination (R2) of the univariate linear regression model between A and SIFY687 and SIFY741 decreased from 0.81 and 0.72 to 0.21 and 0.17, respectively. These results demonstrate the HLB effect on the relationship between A and SIF, and that the SIF could be a proxy to citrus photosynthesis and further used to diagnose early HLB in situ.

A hydroxypropyl methylcellulose (HPMC)-based coating inhibits ethylene-dependent quality changes and reduces superficial scald incidence and blue mould severity during postharvest handling of two apple varieties

The search of new alternatives to substitute postharvest treatments based on synthetic chemicals has gained attention on recent years due to social pressure and stricter legislative policies. Consequently, edible coatings from natural sources have risen as potential solutions to retain postharvest fruit quality. Among these, coatings based on hydroxypropyl methylcellulose (HPMC) have shown potential in preserving fruit quality after harvest. However, scarce studies have explored into their effects on the physiology of climacteric fruits. In this context, the effect of a novel HPMC-based edible coating on fruit postharvest physiology and quality was evaluated in two apple cultivars: ‘Golden Reinders’ and ‘Granny Smith’. In both cultivars, the HPMC-based coating was able to preserve some initial quality attributes, such as firmness and colour, while reducing superficial scald and the severity of blue mould caused by Penicillium expansum. Coated fruit showed reduced ACS activity and ethylene production, delaying changes in ethylene-dependent parameters such as colour and firmness during two different postharvest scenarios: shelf life after harvest and after 3 months of cold storage. Other ripening-associated traits such as starch index, soluble solids content (SSC), and total titratable acidity (TTA) were not affected by the coating application. The coating altered the levels and composition of volatile organic compounds (VOCs), yet without affecting the overall consumer acceptance in most of the studied scenarios. Changes in fruit physiology promoted by the coating, including the decrease of α-farnesene levels and its oxidation products, together with enhanced accumulation of ethanol may reduce the superficial scald incidence in ‘Granny Smith’ and the severity of blue mould rot in the two studied cultivars. Overall, the use of the HPMC-based coating in apples could be useful for maintaining fruit quality and reducing postharvest losses related to mould development and physiological disorders without compromising taste perception.

Double CRISPR knockout of pectin degrading enzymes improves tomato shelf‐life while ensuring fruit quality

Social Impact StatementTomato fruit is an important and popular commodity producing $95.62 billion worldwide. Tomato fruit losses in the supply chain vary between 25% and 42% depending on the production area and the availability of postharvest technologies. For many decades, conventional tomato breeding programs have focused on extending the shelf‐life of fresh‐market varieties. However, in many instances, consumer‐based quality traits were not considered a priority. Consumers are now demanding safe, nutrient‐rich, high‐flavor, and convenient fruit. Here, we demonstrate the use of gene editing to improve fruit shelf‐life and positively impact quality, which can help significantly reduce tomato fruit losses and meet consumer expectations.Summary Finding alternative ways to extend tomato fruit shelf‐life without reducing the quality is critical to ensure the accessibility and likeability of this commodity worldwide. Improving fruit firmness in tomato fresh‐market varieties directly impacts their shelf‐life potential. We simultaneously knocked out two pectin‐degrading enzymes, polygalacturonase (SlPG2a) and pectate lyase (SlPL), key for tomato fruit softening. We expected this gene‐editing approach to result in longer‐lasting fruit without negatively impacting consumer‐based quality attributes. By generating the double clustered regularly interspaced short palindromic repeats (CRISPR) knockout PGPL, we evaluated the combined functions of SlPG2a and SlPL on fruit quality, including shelf‐life attributes like firmness and water loss, fruit marketability, and disease incidence. We also assessed additional attributes impacting consumer acceptance, such as taste and aroma. We revealed that the enzymes SlPG2a and SlPL act additively, significantly impacting fruit firmness and shelf‐life, with the double CRISPR knockout PGPL outperforming the wild‐type fruit. Additionally, fruit quality traits, such as sugar: acid ratio, aroma volatiles, and skin color, were improved or not affected in the double CRISPR knockout PGPL compared to the wild‐type. The discoveries of this research provide new insights into the influence of pectin backbone degradation on fruit physiology and postharvest quality, which can be used in crop improvement programs to make fruit more resilient in the supply chain without compromising quality.

Understanding Environmental and Physiological Factors Affecting the Biology of Diaporthe ilicicola, the Fungus Causing Latent Fruit Rot in Winterberry.

Fruit rot in winterberry is associated with a complex of fungal pathogens. Among them, Diaporthe ilicicola plays a unique role by infecting flowers at bloom, resulting in symptom development in mature fruit. This research aimed to identify at what stage of maturation Ilex fruit can develop disease symptoms and correlate changes in fruit physiology (sugar and phenolic content) and environment (temperature and light intensity) with disease incidence. Correlation data informed in vitro studies testing the ability of putative factors to alter growth of D. ilicicola and select opportunistic fungi within the fruit rot complex: Alternaria alternata, Colletotrichum fioriniae, and Epicoccum nigrum. Results indicated that Ilex fruit do not develop symptoms until 81 to 108 days after inoculation. Temperature and fruit phenolic content were negatively correlated with disease incidence, while fruit sugar concentration and light intensity were positively correlated. In vitro assays revealed that sugar concentration had no effect on the growth of D. ilicicola, but increased light intensity increased hyphal growth and pycnidium formation. Additionally, phenolics extracted from fruit inhibited spore germination in A. alternata, induced secondary conidiation in C. fioriniae, and late season phenolic extracts increased hyphal melanization and pycnidial formation in D. ilicicola. Finally, drops in field temperatures, when replicated in vitro, resulted in a decrease in hyphal growth and spore germination for all fungi. These results suggest that changes in Ilex fruit phenolics during maturation and the increased exposure to light following defoliation may play a role in symptom development by altering D. ilicicola growth within the fruit.

Physiological responses and antioxidant properties of Citrus reticulata under different abiotic stresses mitigated by endogenous melatonin

A major commercial fruit in Pakistan, citrus plays an important role in the economy of the country. The current study examined antioxidant responses in citrus plants exposed to various abiotic stresses like industrial pollution, dust pollution, water logging, drought, and salinity, varying in soil properties and agro-climatic conditions, citrus species and cultivars are most susceptible to abiotic stresses in most citrus-producing countries. The effects of abiotic stresses on citrus plants and fruit physiology were studied in six different sites like Thal desert and pollution stressed areas of Faisalabad. A study of the physiological characteristics of various plants has revealed that citrus plants contain more chlorophyll as the concentration of melatonin increases. Integrative elemental and metabolic techniques have been used to study the potential role of melatonin in citrus defense against abiotic stress and to understand the interactions between melatonin and stress-related phytohormones at the elemental and metabolic levels. Citrus plants sensed abiotic stresses based on morphological observations and physiological analysis. Morphological analysis shows that the abiotic stresses adversely affected the leaves, stems and roots. Physiological analysis shows that antioxidant and micronutrients concentrations (boron (B), zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), molybdenum (Mo), chlorine (Cl)) were also adversely effected in citrus plants. Iron concentration was also found higher in healthy plants with a slight difference. Results show that the activity of antioxidants was increased in stressed plants but the activity of melatonin was slightly changed in healthy plants.