Sugarcane ring spot disease significantly impacts crop yield, necessitating the development of resistant cultivars. This study investigated the pathogenicity, morphology, growth characteristics, and molecular identity of the causal fungal pathogen while assessing the resistance of various sugarcane genotypes. Morphological and molecular analyses identified Curvularia guangxiensis as the primary pathogen. Pathogenicity assays demonstrated that the strain FS1 exhibited greater virulence than the strain BH1, inducing more severe leaf lesions. FS1 also displayed a higher growth rate on potato dextrose agar, triggering earlier symptom onset. A multifactorial analysis of genotype, location, and year revealed significant effects on disease incidence, with broad-sense heritability estimated at 0.7, highlighting substantial genetic and environmental contributions. Cluster analysis categorized sugarcane genotypes into five resistance groups, identifying CP81-1258 and Q202 as highly resistant, while CP88-1762, FN07-2020, and GT94-119 were highly susceptible. These findings provide critical insights for breeding resistant sugarcane cultivars and optimizing disease management strategies.

Soil heterotrophic protists, which are major predators and regulators of bacteria within the soil microbiome, are diverse and widespread unicellular eukaryotes in terrestrial ecosystems. The soil environment is extremely complex, and soil protists are crucial regulators of microorganisms in the interconnected plant microbiome. As most studies have focused on bacteria and fungi, protists are frequently overlooked and understudied components of the soil microbiome, despite their importance and usefulness. Although protists are known to support plant health and performance, the composition and roles of plant-associated protist communities are poorly understood. In particular, the effects of their friendly and hostile nature on rhizosphere bacteria and consequently plant growth are unknown. The adverse effects of soil protists are still poorly explored. This review summarizes the current understanding of how soil protists exert both beneficial and detrimental effects on plant growth and development. It also highlights the effect of soil structure formation and current knowledge gaps along with potential avenues for future advancements in soil biology.

Sugarcane smut, caused by Sporisorium scitamineum, is a major disease threatening global sugarcane production. Biological control agents (BCAs) offer environmentally sustainable alternatives to chemical fungicides, with Bacillus velezensis recognized for its broad-spectrum antifungal properties. In this study, B. velezensis ZHR0 was isolated from sugarcane leaves and evaluated for its antifungal activity through in vitro dual-culture assays and in vivo greenhouse trials. Field application of a ZHR0-based biofertilizer achieved a maximum disease control efficiency of 43.86%. Whole-genome sequencing revealed a 4.04 Mb genome with a GC content of 46.48%, encoding 4,150 genes, including multiple biosynthetic gene clusters (BGCs) associated with secondary metabolite production. In vitro assays showed that ZHR0 inhibited the growth of S. scitamineum by 53.20% and reduced disease incidence in sugarcane seedlings by 45.74%. Notably, BGCs for iturin, fengycin, surfactin, and difficidin were identified, and liquid chromatography-mass spectrometry (LC-MS) confirmed the production of iturin, supporting its role in antifungal activity. These findings demonstrate the biocontrol potential of B. velezensis ZHR0 against sugarcane smut and provide integrated genomic and metabolomic evidence for its application as a sustainable biocontrol agent in sugarcane cultivation.

[This corrects the article DOI: 10.3389/fpls.2022.895230.].

Xanthomonas spp. are plant pathogens known for significantly impacting crop yields. Among them, Xanthomonas albilineans ( Xal) is notable for colonizing the xylem and causing sugarcane leaf scald disease. This study employed homologous recombination to mutate quorum sensing regulatory genes ( rpf) to investigate their role in Xal pathogenicity. Deletions of rpfF (Δ rpfF), rpfC (Δ rpfC), and rpfG (Δ rpfG) led to reduced swarming, growth, and virulence. However, diffusible signal factor (DSF) supplementation restored swarming and growth in the Δ rpfF mutant. Deleting rpfC, rpfG, and rpfF also reduced twitching motility and affected type IV pilus expression. Transcriptomic analysis revealed that Δ rpfF positively regulates flagellar genes. DSF supplementation in Δ rpfF (Δ rpfF-DSF) modulated the expression of flagellar, chemotaxis, and type IV pilus genes. These findings elucidate the DSF-mediated swarming pathway in Xal and provide valuable insights into its regulatory mechanisms.

Soil fungal communities are essential for nutrient cycling, yet their responses to various soil amendments that combine chemical and biological components in agricultural systems remain underexplored. This study evaluated the effect of synthetic nitrogen (N) fertilizer urea alone (CF: 150 kg ha(-1)) and in combinations with different biofertilizers (BF) rates, that is, BF1: BF 1000 kg + urea 150 kg, BF2: BF 1500 kg + urea 150 kg, BF3: BF 1000 kg + urea 100 kg, and BF4: BF 1500 kg + urea 100 kg (all rates per hectares) on sugarcane morphology and rhizosphere fungal communities. Results showed that all biofertilizer treatments significantly (p < 0.05) enhanced sugarcane morphology, with BF2 showing the greatest enhancement in stem diameter (1.5-fold), leaf biomass (3.91-fold), cane biomass (3.07-fold), and root-to-shoot ratio (> 3-fold) compared to the control (no fertilizers). Amplicon sequencing revealed 328 shared operational taxonomic units (OTUs), with BF4 having the most unique OTUs (175). Alpha diversity analysis revealed that BF3 had the highest fungal diversity, while BF1 showed the highest richness. Ascomycota was the dominant phylum across treatments, while BF4 increased the relative abundance of Glomeromycota by 2.3-fold and reduced Fusarium by 2-fold compared to control. BF4 also enriched taxa such as Agaricomycetes and Trichoderma, and strengthened the correlation between fungal communities and ammonium levels. Soil total N was strongly associated with fungal community composition, suggesting that biofertilizers foster key fungal taxa essential for nutrient cycling. These findings highlight the potential of integrating biofertilizers with reduced urea input to enhance soil microbial health and support sustainable agriculture.

This study analyzed the photosynthetic traits of 74 sugarcane genotypes using PAM-2500 and SPAD instruments over three years. Our findings revealed significant variations in photosynthetic characteristics among different genotypes and ratoon years, highlighting the complex interplay between genotype and ratoon age. Notably, the heritability of these traits ranged from 0.70 to 0.86, indicating a strong genetic influence. Through principal component analysis, we identified three critical aspects of photosynthesis: efficiency and light utilization, electron transfer and reaction center status, and chlorophyll content, which collectively accounted for 99.9% of the observed variance. The germplasms were categorized into three efficiency groups—high, moderate, and low—based on their photosynthetic performance. Among these, 45 genotypes were classified as High Photosynthetic Efficiency (HPE), 19 as Moderate Photosynthetic Efficiency (MPE), and 10 as Low Photosynthetic Efficiency (LPE). Importantly, germplasms with high photosynthetic efficiency correlated with increased stalk weight and sucrose content, suggesting potential targets for breeding programs. These findings establish a quantitative framework linking photosynthetic performance with agronomic outputs, providing breeders with measurable selection criteria for developing next-generation sugarcane cultivars optimized for both biomass and sucrose production.

Sugarcane smut, caused by the fungus Sporisorium scitamineum (Sydow), significantly affects sugarcane crops worldwide. Infected plants develop whip-like structures known as sori. Significant variations in these whip lengths are commonly observed, but the physiological and molecular differences causing these morphological differences remain poorly documented. To address this, we employed conventional microbe isolation, metagenomic, and metabolomic techniques to investigate smut-infected sugarcane stems and whips of varying lengths. Metagenomics analysis revealed a diverse fungal community in the sugarcane whips, with Sporisorium and Fusarium genera notably present (>1%) in long whips. Isolation techniques confirmed these findings. Ultra-performance liquid chromatography analysis (UHPLC-MS/MS) showed high levels of gibberellin hormones (GA3, GA1, GA4, GA8, and GA7) in long whips, with GA4 and GA7 found exclusively in long whips and stems. Among the prominent genera present within long whips, Fusarium was solely positively correlated with these gibberellin (GA) hormones, with the exception of GA8, which was positively correlated with Sporisorium. KEGG enrichment analysis linked these hormones to pathways like diterpenoid biosynthesis and plant hormone signal transduction. These findings suggest that Fusarium may influence GA production leading to whip elongation. Our study reveals fungal dynamics and gibberellin responses in sugarcane smut whips. Future research will explore the related molecular gibberellin synthesis mechanisms.

Abstract Background Saccharum spontaneumL. is a closely related species of sugarcane and has become an important genetic component of modern sugarcane cultivars. Stem development is one of the important factors for affecting the yield, while the molecular mechanism of stem development remains poorly understanding in S. spontaneum. Phenylalanine ammonia-lyase (PAL) is a vital component of both primary and secondary metabolism, contributing significantly to plant growth, development and stress defense. However, the current knowledge about PAL genes in S. spontaneum is still limited. Thus, identification and characterization of the PAL genes by transcriptome analysis will provide a theoretical basis for further investigation of the function of PAL gene in sugarcane. Results In this study, 42 of PAL genes were identified, including 26 SsPAL genes from S. spontaneum, 8 ShPAL genes from sugarcane cultivar R570, and 8 SbPAL genes from sorghum. Phylogenetic analysis showed that SsPAL genes were divided into three groups, potentially influenced by long-term natural selection. Notably, 20 SsPAL genes were existed on chromosomes 4 and 5, indicating that they are highly conserved in S. spontaneum. This conservation is likely a result of the prevalence of whole-genome replications within this gene family. The upstream sequence of PAL genes were found to contain conserved cis-acting elements such as G-box and SP1, GT1-motif and CAT-box, which collectively regulate the growth and development of S. spontaneum. Furthermore, quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that SsPAL genes of stem had a significantly upregulated than that of leaves, suggesting that they may promote the stem growth and development, particularly in the + 6 stem (The sixth cane stalk from the top to down) during the growth stage. Conclusions The results of this study revealed the molecular characteristics of SsPAL genes and indicated that they may play a vital role in stem growth and development of S. spontaneum. Altogether, our findings will promote the understanding of the molecular mechanism of S. spontaneum stem development, and also contribute to the sugarcane genetic improving.

Guangxi is the leading sugarcane-producing area in China. Due to the Panama disease outbreak in banana gardens, sugarcane and banana rotation was recommended. A field experiment with the newly released sugarcane cultivar Zhongzhe 1 (ZZ1) was conducted to understand the role of the sugarcane–banana rotation system in shaping the rhizosphere microbiota. Fields in the region possess characteristics of red laterite soil. Using Illumina HiSeq sequencing to analyze soil samples’ 16S rRNA V3-V4 region, the preceding banana rotation field had relatively greater bacterial diversity than the monoculture sugarcane field. Proteobacteria, Chloroflexi, Actinobacteria, and Acidobacteria were the dominant phyla, with distinct taxa enriched in each environment. However, the preceding sugarcane monoculture field enriched functional groups related to nitrogen fixation and cellulolysis. Network analysis highlighted contrasting network structures between sugarcane and banana rhizospheres, suggesting differential stability and susceptibility to environmental influences. Furthermore, correlations between soil properties and bacterial alpha-diversity underscored the influence of preceding crops on rhizosphere microbial communities. This research enhances our understanding of crop rotation effects on soil microbial ecology and provides insights into optimizing agricultural practices for enhanced soil health and crop productivity. Future studies should explore the underlying mechanisms driving these interactions and evaluate the long-term impacts of crop rotation on soil microbial dynamics.

ABSTRACTSugarcane is a critical sugar and bioenergy crop in China. However, numerous factors, including root rot disease, hamper its yield. Root rot disease is a severe agricultural issue, reducing yield and threatening sustainable crop production. The current study aimed to explore the fungal community structure, identify and characterize the primary pathogen for sugarcane root rot in Guangzhou, China. Eighty-nine samples of sugarcane root, stalk, rhizosphere soil, and irrigation water were collected from five sites in Guangzhou, China. Subsequently, 276 fungal strains were isolated to identify the primary pathogens. The five most common genera identified were Penicillium, Fusarium, Gongronella, Trichoderma, and Cladosporium. Fusarium was more prevalent in the infected soil samples than in healthy ones. Pathogenic assays of the strains revealed that the strain GX4-46 caused 80% of the disease. The strain was confirmed as Fusarium commune through phylogenetic and genome sequence analysis. Rhizosphere soil samples from different regional crops were collected to better understand the fungal community structure and the primary pathogen. We observed a significant presence of Fusarium in irrigation water, indicating that the root rot disease could originate from the irrigation water and then spread as a soil-borne disease. This research is pioneering and one of the most comprehensive investigations on the occurrence and prevalence of sugarcane root rot disease. This study will serve as a reference for expanding the sugarcane industry and a foundation for further exploration and control of root rot.IMPORTANCESugarcane, a significant economic crop, faces challenges due to root rot pathogens that accumulate each year in plants and soil through ratoon planting. This disrupts soil microbial balance and greatly impedes sugarcane industry growth. Symptoms range from wilting and yellowing leaves to stunted growth and reduced seedling tillers. The rhizosphere microbiota plays an important role in plant development and soil health. Little is known about root rot fungal community structure, especially in sugarcane. Here, we focused on exploring the main causative pathogen of root rot in the area alongside a detailed survey of the rhizosphere soil of different severity sugarcane cultivars and rotation crops of the region. To validate the findings, we also investigated the irrigation water of the area. Our study revealed Fusarium commune as the causative pathogen of root rot in the area, primarily originating from water and later as soil-borne. Using Trichoderma can control the disease effectively.

Sugarcane is a globally significant crop for sugar and energy production, and developing high light-efficiency sugarcane varieties is crucial for enhancing yield and quality. However, limited research is available on the screening of sugarcane germplasm with high photosynthetic efficiency, especially with different leaf positions. The present study, conducted in Guangxi, China, aimed to analyze the photosynthetic characteristics of 258 sugarcane varieties at different leaf positions over three consecutive years in field experiments. The results showed significant differences in photosynthetic characteristics among genotypes, years, and leaf positions. Heritability estimates for various photosynthetic parameters ranged from 0.76 to 0.88. Principal component analysis revealed that the first three principal components accounted for over 99% of the cumulative variance. The first component represented photosynthetic efficiency and light utilization, the second focused on electron transfer and reaction center status, and the third was associated with chlorophyll content. Cluster and discriminant analysis classified sugarcane genotypes into three categories: high photosynthetic efficiency (HPE) with 86 genotypes, medium photosynthetic efficiency (MPE) with 60 genotypes, and low photosynthetic efficiency (LPE) with 112 genotypes. Multi-year trials confirmed that HPE sugarcane genotypes had higher single-stem weight and sucrose content. This study provides valuable insights into the photosynthetic physiological characteristics of different sugarcane varieties, which can contribute to further research regarding high yields and sugar breeding.

Xanthomonas albilineans (Xal) is a gram-negative bacterial pathogen responsible for developing sugarcane leaf scald disease, which engenders significant economic losses within the sugarcane industry. In the current study, homologous recombination exchange was carried out to induce mutations within the virB/D4-like type IV secretion system (T4SS) genes of Xal. The results revealed that the virB11-deletion mutant (ΔvirB11) exhibited a loss in swimming and twitching motility. Application of transmission electron microscopy analysis further demonstrated that the ΔvirB11 failed to develop flagella formation and type IV pilus morphology and exhibited reduced swarming behaviour and virulence. However, these alterations had no discernible impact on bacterial growth. Comparative transcriptome analysis between the wild-type Xal JG43 and the deletion-mutant ΔvirB11 revealed 123 differentially expressed genes (DEGs), of which 28 and 10 DEGs were notably associated with flagellar assembly and chemotaxis, respectively. In light of these findings, we postulate that virB11 plays an indispensable role in regulating the processes related to motility and chemotaxis in Xal.

The southern area of China, particularly Guangxi region, contributes significantly to the nation's sugar industry. Nevertheless, this region faces challenges due to excessive use of nitrogen fertilizer in sugarcane cultivation, leading to land degradation. Biofertilizers (BF) signifies an important turning point in this challenging scenario globally. However, there is few literature on the co-application of biofertilizers (BF) and nitrogen (N) fertilizers and their effect on sugarcane rhizosphere microbial community, soil chemical properties, and above-ground growth. This study employed the combination of six different treatment in a netted greenhouse experiment and the results showed a significant variations in sugarcane biomass, soil chemical properties and rhizosphere bacterial community. Further, in comparison to the control and only N fertilization, the combined application of biofertilizer and nitrogen (BF+N) significantly affected the rhizosphere microbes as per the Shannon and Chao1 index (p < 0.05). The altered relative abundance of microbes significantly affected soil chemical properties, including pH, total carbon, total nitrogen, ratio of carbon and nitrogen, ammonium nitrogen, and nitrate-nitrogen. Ternary plot analysis further showed the enriched bacterial genera i.e., Burkholderia, Sphingomonas, Meosrhizobium, Rhizobacter, Nitrospirae, and Dyella, as a result of BF amendment. Redundancy analysis also validated the results and showed that soil organic matter, total carbon, and its ratio to nitrogen and ammonium nitrate were the key edaphic factors in altering the microbial community of sugarcane rhizosphere. In conclusion biofertilizer (1500 kg.ha(-1)) combined with 150 kg.ha(-1) of urea (BF2) could be an effective strategy for enhancing sugarcane growth, reducing chemical fertilizers, and moving towards sustainable soil environment in continuous sugarcane cropping system.

Ratooning in sugarcane often leads to soil problems such as degradation, acidification, and soil-borne diseases that negatively impact agriculture output and sustainability. Understanding the alteration in bacterial communities, activities, and their diversity connected to the plant and soil under consecutive ratooning still needs to be clarified. To address this gap, multidisciplinary approaches such as Illumina sequencing and measurement of soil nutrients and enzymes were used in this study to analyze soil samples in a field with three consecutive ratooning sugarcane crops. The results revealed a decline in crop yield and significant changes (P < 0.05) in soil nutrients and bacterial diversity. Ratooning resulted in an acidic environment that potentially affected soil nutrients and enzyme activity responsible for the cycling of carbon, nitrogen, and phosphorous. Non-metric dimensional scaling (NMDS) confirmed the effect of ratooning on soil attributes. Moreover, a positive correlation between soil physiochemical properties and soil enzymes was observed. Alpha diversity indices indicated greater bacterial diversity in ratooning sugarcane. Bacterial diversity varied throughout the ratooning crop, and significant (P < 0.05) changes in the relative abundance of specific phyla were observed. For example, the relative abundance of Proteobacteria was decreased, and Acidobacteria was increased. Furthermore, the relative abundance of bacterial phyla was strongly correlated with soil attributes (enzymes and nutrients). Additionally, ratooning results in the depletion or enrichment of important agriculture microbial genera such as Sphingomonas, Burkholderia, and Acidothermus (P < 0.05), respectively. In conclusion, ratooning led to soil acidification, decreased fertility, and altered microbial structure and activity. Thus, restraining soil acidity by means of liming or biofertilizers to maintain soil nutrients, enzymatic activities, and microbial structure could benefit plants and soil to help create a long-term eco-friendly sugarcane cropping system.

Biochar application is an efficient amendment to improve soil chemical properties. However, its influence on enzyme activities and soil health, especially fungal diversity, is deficient in the rhizosphere of mountainous apple trees. A pot experiment was conducted over the course of a year with six different biochar rates [CK (0), T1 (2), T2 (4), T3 (6), T4 (8), and T5 (10) t ha−1] and a basal dose of inorganic fertilizer. Experimental findings revealed that: (i) Compared to the CK treatment, the biochar-applied treatment (T5) across the months (3, 6, 9, and 12) significantly improved soil physiochemical properties and enzyme activities [urease (UE), alkaline phosphatase (ALP), catalase (CAT), and sucrase (SC)]. (ii) The T5 of the biochar-applied treatment compared to the CK significantly reduced the dominant relative abundance of the phylum Ascomycota. However, Basidiomycota and Chytridiomycota phyla members showed an optimized trend with biochar-applied treatments. Similarly, the fungal genera with the largest relative abundance in the T5 was Coprinellus, followed by Helminthosporium, Gibberella, Coniothyrium, Paraconiothyrium, and Aplosporella. Furthermore, Alternaria and Amanita were the only genera that showed the lowest trend with the biochar-applied treatments. (iii) The fungal richness and diversity of the biochar-applied treatments exhibited a lower trend than the CK treatment. Moreover, the heatmap correlation was negative between the Ascomycota with soil organic matter (SOM) and total nitrogen (T.N), and Mucoromycota and Olpidiomycota with UE, ALP, and SC activities. Biochar-applied treatment (T5) with the required inorganic fertilizer is significant for enhancing soil characteristics, which may aid the productivity of apple orchards.

Biochar is an important soil amendment that can enhance the biological properties of soil, as well as nitrogen (N) uptake and utilization in N-fertilized crops. However, few studies have characterized the effects of urea and biochar application on soil biochemical traits and its effect on paddy rice. Therefore, a field trial was conducted in the early and late seasons of 2020 in a randomized complete block design with two N levels (135 and 180 kg ha−1) and four levels of biochar (0, 10, 20, and 30 t ha−1). The treatment combinations were as follows: 135 kg N ha−1 + 0 t B ha−1 (T1), 135 kg N ha−1 + 10 t B ha−1 (T2), 135 kg N ha−1 + 20 t B ha−1 (T3), 135 kg N ha−1 + 30 t B ha−1 (T4), 180 kg N ha−1 + 0 t B ha−1 (T5), 180 kg N ha−1 + 10 t B ha−1 (T6), 180 kg N ha−1 + 20 t B ha−1 (T7) and 180 kg N ha−1 + 30 t B ha−1 (T8). The results showed that soil amended with biochar had higher soil pH, soil organic carbon content, total nitrogen content, and mineral nitrogen (NH4+-N and NO3−-N) than soil that had not been amended with biochar. In both seasons, the 20 t ha−1 and 30 t ha−1 biochar treatments had the highest an average concentrations of NO3–-N (10.54 mg kg−1 and 10.25 mg kg−1, respectively). In comparison to soil that had not been treated with biochar, the average activity of the enzymes urease, polyphenol oxidase, dehydrogenase, and chitinase was, respectively, 25.28%, 14.13%, 67.76%, and 22.26% greater; however, the activity of the enzyme catalase was 15.06% lower in both seasons. Application of biochar considerably increased the abundance of ammonia-oxidizing bacteria (AOB), which was 48% greater on average in biochar-amended soil than in unamended soil. However, there were no significant variations in the abundances of ammonia-oxidizing archaea (AOA) or nitrite-oxidizing bacteria (NOB) across treatments. In comparison to soil that had not been treated with biochar, the average N content was 24.46%, 20.47%, and 19.08% higher in the stem, leaves, and panicles, respectively. In general, adding biochar at a rate of 20 to 30 t ha−1 with low-dose urea (135 kg N ha−1) is a beneficial technique for improving the nutrient balance and biological processes of soil, as well as the N uptake and grain yield of rice plants.

Minimizing the use of chemical fertilizers and investigating an appropriate ecofriendly level of nitrogen fertilizer is the key to sustainable agriculture. Sugarcane is the main cash crop of China, especially in the Guangxi region. Information regarding the effect of different nitrogen levels on sugarcane rhizosphere microbiota is still limited. In this study, we evaluated the effect of four different levels of nitrogen fertilizers on rhizosphere bacterial composition using high throughput sequencing, along with soil physiochemical properties, sugarcane agronomic and yield performance. The four treatment combinations were CK (no fertilizers), L (Low, 100 kg ha(-1)), M (Medium, 150 kg ha(-1)), and H (High, 200 kg ha(-1)). The results showed that M nitrogen application significantly altered the rhizosphere bacterial community, soil properties, and sugarcane yield. The richness and evenness of the bacterial community were higher in M treatment than CK. In M treatment important bacterial phyla Acidobacteria and Proteobacteria increased by 47 and 71%, respectively; and at genus level, Acidothermus and Bradyrhizobium increased by 77.2 and 30.3%, respectively, compared to CK. Principal component analysis (PCA) and cluster analysis further confirmed the level of differences among the treatments. The PCA analysis explained 80% of the total variation among the treatments. Spearmen correlation heatmap showed that environmental factors such as pH, AP (available phosphorous), AK (available potassium), and SCAT (soil catalase) were the key factors impacting sugarcane rhizosphere microbiome composition. The H and L nitrogen application alter the bacterial community and sugarcane performance but the M nitrogen application appears to be ecofriendly, productive, and an appropriate nitrogen application rate that could be further used in the Guangxi region.

Plant extracts represent a rich repository of metabolites with antioxidant and antimicrobial properties. Neem (Azadirachta indica) is a medicinal plant considered the tree of the 21st century. In this study, we investigated the antioxidant and antimicrobial effects of propyl disulfide (PD), a major volatile compound in neem seed, against the pericarp browning (BI), microbial decay incidence (DI), and water loss of longan fruit. Fresh longan cv. Shixia samples were packaged in oriented polypropylene (OPP) and polyethene (PE) packages of different thicknesses (20, 40, and 60 µm). Sterile gauze was fixed inside the packages and 500 uL of PD was placed on them to avoid the direct contact of PD with fruit samples. Packages were sealed immediately to minimize vaporization and stored at 12 ± 1 °C for 18 days. Fruit samples packaged in open net packages served as controls. The results showed that fruit treated with PD in OPP and PE packages significantly prevented losses of water, DI, and BI compared to control treatment. PD also maintained the color, TSS values, TA values, pH values, high peel firmness, high TPC content, and high TFC content, and reduced the activity levels of PPO and POD. Scanning electron microscope (SEM) analysis indicated that the exocarp, mesocarp, and endocarp of longan peel were smooth, uniform, and compact with no free space compared to control, where crakes, a damaged and loose structure, and a lot of fungal mycelia were found. The shortest shelf life of 9 days was observed in control as compared to 18 days in OPP-20 and OPP-40; 15 days in OPP-60, PE-20, and PE-40; and 12 days in PE-60 packaging films. Therefore, PD as a natural antioxidant and antimicrobial agent, in combination with OPP-20 and OPP-40 polymeric films, could successfully be applied commercially to extend the postharvest shelf life of longan.

A changing climate and global warming have adversely affected Pakistan’s moist and dry temperate vegetation. Abies pindrow (fir) (Royle ex D.Don) Royle and Picea smithiana (spruce) Wall.) Boiss are the two major representative species of the moist and dry temperate forests in Northern Pakistan. The dendroclimatic study of both species is crucial for the assessment of climate variability at various spatial and temporal scales. This study examined the dendroclimatology of fir and spruce, and analyzed the growth–climate relationship along the latitudinal gradient. Two hundred and nineteen samples (ring cores) of the two species were collected from five different sites (Shogran (SHG), Upper Dir (UDS), Bahrain Swat (BSG), Astore Gilgit (NPKA), and Sharan Kaghan (SHA)) in Northern Pakistan. The cores were cross-dated, and chronologies were generated for the species and climatic data (precipitation, temperature, and Palmer Drought Severity Index (PDSI)) correlated with radial growth. The interspecies correlations for fir were calculated as 0.54, 0.49, 0.52, 0.60, and 0.48 for SHG, UDS, BSG, NPKA, and SHA, respectively, whereas in the case of spruce, the interspecies correlations were 0.44 for SHG, 0.55 for UDS, and 0.49 for BSG. Climate variability was observed in the samples of both species, which showed significant drought and humid years at specific intervals. With respect to the correlation between tree-ring width and climatic factors, a positive correlation was observed between fir growth and summer season precipitation, mean temperature, and PDSI in the spring, summer, and autumn seasons. Similarly, the growth of spruce was positively correlated with precipitation (in February, September, and May) and PDSI (in the summer and autumn seasons); however, no correlation was observed between monthly temperature and spruce growth. The relationship of fir and spruce growth with seasonal precipitation and PDSI showed a change from a negative to a positive correlation after 1980, following rapid warming. During the winter and spring, the correlation coefficient between fir radial growth and seasonal temperature showed an initial upward trend followed by a progressive decrease along with increasing latitude. Seasonal variations were observed regarding the correlation coefficient between spruce radial growth and increasing latitude (increasing in winter; a decreasing trend in spring and summer; an initial increase and then a decrease in autumn). In the same way, the correlation of seasonal temperature and PDSI with the radial growth of both species showed increasing trends with increasing latitude, except in the autumn season.