Litchi Research Articles

Occurrence and Health Risk Assessment of Heavy Metals in Lychee (Litchi chinensis Sonn., Sapindaceae) Fruit Samples

This study aimed to assess the occurrence of eight heavy metals in lychee (Litchi chinensis Sonn.) fruit samples collected from orchards of the Dehradun and Haridwar districts in Uttarakhand, India. Lychee fruit samples were collected from ten (10) sampling locations from May to June 2023 and analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). Results showed that lychee fruit samples showed varying levels of selected heavy metals, i.e., Cd (0.009–0.095 mg/kg), Cr (0.079–0.960 mg/kg), Cu (0.095–0.258 mg/kg), Fe (0.254–0.531 mg/kg), Pb (0.000–0.011 mg/kg), Mn (0.862–1.903 mg/kg), Ni (0.166–0.310 mg/kg), and Zn (0.076–0.149 mg/kg). It was observed that lychee fruit sampling sites near urban and industrial areas had higher concentrations of heavy metals as compared to those in rural and agricultural areas. In addition, principal component analysis (PCA) and clustered heatmap dendrogram results showed that several sites had significant similarities in terms of heavy metal availability. Overall, the levels of all heavy metals were below the safe limits as suggested by health risk studies. The selected indices such as daily intake of metals (DIM), health risk index (HRI), and target hazard quotient (THQ) did not exceed the standard limit which indicated consumption of lychee fruit was safe at all sampling sites. The results of this study emphasize the need to regularly monitor lychee heavy metal levels and implement sustainable agricultural and environmental practices to reduce contamination sources.

Identification and expression analysis of WRKY superfamily genes under lychee downy blight stress in lychee

AbstractWRKY proteins comprise a large family of transcription factors that play important roles in plant growth, development, and responses to stress, but little information is available about these genes in lychee (Litchi chinensis Sonn.). Despite being a popular fruit worldwide, lychee is highly vulnerable to lychee downy blight (LDB; caused by Peronophythora litchii), a major disease affecting lychee. Based on lychee whole‐genome data, a total of 50 LcWRKY genes were identified across 15 chromosomes. According to a conserved domain and phylogenetic analysis, these 50 LcWRKYs were classified into three distinct subfamilies. Gene structure analysis revealed the presence of 2–11 exons in the LcWRKYs. Cis‐acting regulatory element analysis identified many stress‐response elements in LcWRKY promoters. Moreover, a comprehensive 2‐year investigation involving the screening of a lychee natural population led to the identification of Guiwei and Yurong1 as displaying stable susceptibility and resistance against LDB, respectively. Furthermore, expression patterns indicated that LcWRKY13, LcWRKY17, and LcWRKY34 were significantly upregulated in response to LDB induction, while LDB suppressed the expression of LcWRKY11. These findings suggest that these four genes may play a crucial role in lychee resistance to LDB. The present study has provided a foundation for future investigations of LcWRKY gene function in lychee.

Effect of Morphological Characteristics of Fruit Orchards on Soil Physio-chemical Properties

Biophysical characteristics of 16-year-old fruit orchards and their influence on soil physico-chemical properties of sixteen-year-old fruit orchards established at Krishi Vigyan Kendra, Birouli, Samastipur (Bihar) were compared. Fruit orchards were Mango (Mangifera indica) var. Malda, Litchi (litchi chinensis) var. China and Aonla (Emblica officinalis) var. NA-7. An investigation was undertaken to evaluate the dynamics of Oxidisable Organic Carbon (Coc), SOC sequestration, Bulk Density (BD), pH and Electrical Conductivity (EC) in fruit orchards. All the orchards significantly improved SOC showing 12.9 to 44.6 % higher than that in open (without trees) and followed the order: Aonla > Litchi > Mango. The total SOC increased by 10 to 20 % at the surface and 15 to 35 % in the lower depths. The crown diameter of Mango, Litchi and Aonla orchards were 11.64 m, 8.61 m and 8.6 m and girth at breast height (GBH) varied from 9.53 m in Aonla orchard to 5.6 m in Litchi orchard. By and large, Aonla orchard may be considered as the best orchard production system from the standpoint of SOC build up and improvement in soil physic-chemical properties. Hence, its promotion and expansion as land-use practices in the calcareous belt of Bihar will be helpful for food security and mitigating climate change.

Agrobacterium tumefaciens-mediated transformation of embryogenic callus and CRISPR/Cas9-mediated genome editing in ‘Feizixiao’ litchi

Litchi (Litchi chinensis Sonn.) is a type of commercially prevalent subtropical and tropical fruit. Since litchi has a highly heterozygous genetic background and a long reproductive cycle, conventional breeding methods (such as hybridization) have limited ability to nurture new litchi cultivars. Here, an efficient and stable Agrobacterium tumefaciens-mediated genetic transformation of embryogenic callus was established in ‘Feizixiao’ litchi. Transgenic materials were verified using polymerase chain reaction (PCR) analysis, β-glucuronidase (GUS) assay, and green fluorescent protein (GFP) assay. To implement the technology of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/associated protein 9 (CRISPR/Cas9) technology in ‘Feizixiao’ litchi and verify the validity of these transformation systems, the litchi polyphenol oxidase gene (LcPPO, JF926153) was knocked out. Various categories of mutations, covering base insertions, deletions, and substitutions, were found in transgenic materials via sequence analysis. The transformation system achieved high feasibility and efficiency, and the system of CRISPR/Cas9 was successfully employed to edit genes in ‘Feizixiao’ litchi. This work provides an essential foundation for investigating the functions of genes and accelerating litchi genetic improvement.

Antifungal efficacy of LEDs against major postharvest pathogens of litchi fruit in vitro and in vivo

Postharvest fruit diseases in litchi (Litchi chinensis Sonn.) caused by fungi are one of the major problems in the fruit industry. Light-emitting diodes (LEDs) technology is a promising alternative to fungicides to control postharvest fungal decay. This study aimed to evaluate the antifungal potential of LEDs against postharvest pathogens Geotrichum candidum and Fusarium sp. isolated from litchi fruit in vitro and in vivo. Results showed that violet light (410–420 nm) was more effective at inhibiting both fungi than other wavelengths of LED. The inhibition effect was dose-dependent, with spore germination completely inhibited and mycelial growth inhibited by about 65–79% when LED illumination for 10 h. In vivo assays demonstrated that LED reduced the population of G. candidum and Fusarium sp. by more than 2 log CFU/g (∼99%) on litchi fruit. However, different surface characteristics of the fruit produced different shielding effects on this technology. In addition, there were also species specificity in the inactivation effect, with Fusarium sp. being more resistant to LED than G. candidum. Notably, the antifungal efficacy at 25 °C was greater than at lower temperatures. These results demonstrate that LED holds great potential as a postharvest preservation technology for reducing the risk of fruit spoilage. The efficacy of treatment could be associated with multiple factors (e.g., wavelengths, exposure duration, temperature, fungal species, and fruit surface characteristics) and therefore needs to be well considered when applying the technique in food systems.

Tissue Specific Distribution and Activation of Sapindaceae Toxins in Horses Suffering from Atypical Myopathy.

Equine atypical myopathy is caused by hypoglycin A (HGA) and methylenecyclopropylglycine (MCPrG), the known protoxins of sycamore maple (Acer pseudoplatanus). Various tissues from five atypical myopathy cases were analyzed but only HGA was found. Whether deamination of MCPrG has already occurred in the intestine as the first stage of metabolization has not been investigated. Activation of the protoxins to methylenecyclopropylacetyl (MCPA)-CoA and methylenecyclopropylformyl (MCPF)-CoA, respectively, occurred mainly in the skeletal muscles, as evidenced by very high concentrations of MCPA-carnitine and MCPF-carnitine in this tissue. Inhibition of the acyl-CoA dehydrogenases of short- and medium-chain as well as branched-chain fatty acids by the toxins led to a strong increase in the corresponding acylcarnitines, again preferentially in skeletal muscles. An accumulation of the long-chain acylcarnitines beyond the level of the control samples could not be detected in the tissues. As a high amount of HGA was always found unmetabolized in the organs, we speculate that targeting the interruption of further metabolization might be a way to stop the progression of intoxication. Inhibition of the mitochondrial branched-chain amino acid aminotransferase, i.e., the first enzyme responsible for the activation of sycamore maple protoxins, could be a therapeutic approach.

Effect of Oxalic Acid on Control of Post-harvest Browning of Litchi (Litchi chinensis L.)

Post-harvest browning of litchi is a common phenomenon that occurs due to enzymatic and non-enzymatic reactions. Enzymatic browning is primarily caused by polyphenol oxidase (PPO) activity, leading to the formation of brown pigments. Non-enzymatic browning is caused by the Maillard reaction between reducing sugars and amino acids. Factors such as temperature, humidity, and mechanical damage can accelerate browning. Proper handling, storage, and the use of antioxidants can help minimize post-harvest browning, extending the shelf life and maintaining the visual appeal of litchi fruits. The present investigation was laid out in the post-harvest laboratory of horticulture department, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj during the year 2022-2023. The experiment was laid out in the CRBD with 8 treatments and 3 replications. Litchi fruit, Cv. Purvi (about 80%- matured stage), were harvest from a Local market Prayagraj, fruit was selected for uniformity of size and colour, and blemished and diseased fruit were discarded. The selected fruit were dipped in different oxalic acid concentration solution (0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0mM) and Bavistin (0.05mg) as the control) for 10 mint 4 h of harvest, and then air dried. Each 10 fruit of the treated fruit was packed into a plastic punnet and wrapped with a 0.2-mm polyethylene bag, and then stored in an ambient condition. Post-harvest storage studies revealed that under ambient and refrigerated storage conditions T8 Oxalic acid (4.0mM) + Bavistin (0.05%) treatment showed slower rate of reduction on fruit length (cm) and fruit weight (g), browning (%) were significantly affected by treatments. There was significant effect of treatments on chemical parameters like pH, TSS (0Brix), acidity (%), ascorbic acid (mg100g), reducing sugar under ambient and refrigerated storage at different day’s intervals.

Physicochemical Properties and Potential Food Applications of Starches Isolated from Unconventional Seeds: A Review

AbstractStarch is a natural carbohydrate that is commonly isolated from conventional sources such as corn, cassava, potato, wheat, and rice. However, in recent years new sources of starch have been studied, named as unconventional sources, usually from seeds and legumes, which have comparable properties to traditional starch sources. In recent years, new sources of starch from various seeds have been observed, including durian (Durio zibethinus Murr.), jackfruit (Artocarpus heterophyllus), loquat (Eriobothrya japonica), lychee (Litchi chinensis Sonn.), mango (Mangifera indica), tamarind (Tamarindus indica L.), pine, or pinhão (Araucaria angustifolia), etc. On a laboratory scale, the extraction of starch from unconventional sources has generally been carried out with water, however, despite being an old method, good efficiencies have been obtained. In this review, it is shown that starches from unconventional sources have promising physicochemical properties, good digestibility performance, and applicability in the food area.

Climate and soil suitability zonation for Litchi (Litchi chinensis) in India using geo-science tool-based analytical hierarchy process

Litchi (Litchi chinensis) plantations in new areas without any land suitability assessment putting small farmers at risk of economic loss. The unique capability of the Geographical information system (GIS) for integration, analysis, and interpretation of spatial data has been leveraged for the identification, and mapping of potential litchi cultivation zones in India to help farmers and policymakers make informed decisions. Five climate-derived parameters including the number of days per year having a minimum temperature <12 °C (CumD-Tmin < 12), number of days per year having a minimum temperature <0 °C (CumD-Tmin < 0), number of days per year having a mean temperature <20 °C (CumD-Tmean < 20), highest daily maximum temperature (°C) (Thmax) and average annual rainfall (mm), and eight soil parameters viz. soil depth, clay content, slope, stoniness, drainage conditions, pH, electrical conductivity (EC), organic carbon were identified as suitability parameters. Geospatial data at a grid 0.1° × 0.1° of all the identified climate parameters and spatial layers of eight soil data were analysed using Arc-GIS 10.2. The analytical hierarchy process (AHP) was used for assigning relative weightage to the suitability parameters. Using the weighted sum of feature layers, a climate suitability map, a soil suitability map and finally a litchi cultivation potential zones (LCPZs) map were developed. The northward shift of the suitability zone is indicated under climate change projections. The new approach of identifying suitability parameters in relation to the plant’s requirement and its integration in GIS using AHP can be extended to other crops and regions.

Genome-Wide Identification, Characterization, and Expression Analysis of the NAC Gene Family in Litchi chinensis.

NAC proteins play an essential role in the growth and development of litchi, especially during reproductive development. However, a comprehensive analysis of the litchi NAC gene family is currently absent. Based on information from the litchi genome, we found that the 112 NAC genes of litchi show an uneven distribution on the chromosomes. Phylogenetic and conserved structural domain analyses indicated that different types of variability were exhibited in the family of litchi NACs (LcNACs). Gene covariance analysis showed that the LcNACs showed better similarity in the same genus than with Arabidopsis. We further investigated the differential expression patterns of LcNACs in buds and rudimentary leaves of litchi. qRT-PCR results implied that they were involved in the process. Profiling of LcNAC promoter elements in litchi showed that they were extensively involved in light response, phytohormone regulation, abiotic stress response, and plant growth and development processes. This study provides new insights into the identification, structural characterization, tissue-specific expression analysis, and promoter response elements of LcNACs. It reveals the characteristics of the LcNACs and lays the foundation for the subsequent understanding of its biological functions and molecular regulatory mechanisms.

Detection of Hypoglycin A and MCPrG Metabolites in the Milk and Urine of Pasture Dairy Cows after Intake of Sycamore Seedlings.

Hypoglycin A (HGA), methylenecyclopropylglycine (MCPrG), hypoglycin B (HGB), and γ-glutamyl-α-(methylenecyclopropyl) glycine (γ-glutamyl-MCPrG) are secondary plant metabolites occurring in sycamore maple (Acer pseudoplatanus) as well as several other Sapindaceae (e.g., Blighia sapida). By interfering with energy metabolism, they may cause severe intoxication in humans and other species. However, to date, there is not enough data available concerning the intake, metabolism, or excretion of sycamore maple toxins in dairy cows. In May 2022, five cows were observed over four days, when they had first access to a pasture with two sycamore maples. Grazing of their seedlings that grew numerously in between the pasture plants was monitored by direct observation. Milk samples were drawn both from individual cows and from the bulk tank. Spontaneous urine samples were collected from all cows on day 3 after access to the pasture. Seedlings (100 g) were sampled on the pasture and analyzed, together with milk and urine samples, for sycamore toxins and their metabolites using liquid chromatography-tandem mass spectrometry and liquid chromatography-high-resolution mass spectrometry. Cows ingested sycamore seedlings while grazing. Values of HGA in milk were below the limit of quantification. However, metabolites of HGA and MCPrG were detected in individual milk samples already at the end of the first day of grazing. Urine samples of all five cows showed higher concentrations of conjugated HGA and MCPrG metabolites than in milk. Observations suggest that dairy cows may have a low susceptibility toward sycamore maple toxins. However, whether this could be attributed to foregut fermenting species in general requires further elucidation.

Postharvest Calcium Chloride Treatment Strengthens Cell Wall Structure to Maintain Litchi Fruit Quality.

Litchi (Litchi chinensis Sonn.) fruit deterioration occurs rapidly after harvest and is characterized by pericarp browning, pulp softening, and decay. In this study, we found that calcium chloride (CaCl2) treatment (5 g L-1 CaCl2 solution vacuum infiltration for 5 min) affected the cell wall component contents and cell wall-degrading enzyme activities of litchi fruit during storage at room temperature. CaCl2 treatment significantly increased the contents of Ca2+ and cellulose, while it decreased the water-soluble pectin content, and the activities of polygalacturonase, β-galactosidase, and cellulase in the litchi pericarp. Meanwhile, the treatment resulted in significantly increased contents of Ca2+, water-soluble pectin, ionic-soluble pectin, covalent-soluble pectin and hemicellulose, and upregulated activities of pectinesterase and β-galactosidase, while significantly decreasing the activities of polygalacturonase and cellulase in litchi pulp. The above results indicate that CaCl2 treatment strengthened the cell wall structure of litchi fruit. More importantly, the enzymatic browning of the pericarp, softening of the pulp, and disease incidence were delayed. The treatment had a more pronounced effect on the pericarp than on the pulp. We consider CaCl2 treatment to be a safe and effective treatment for maintaining the postharvest quality of litchi fruit.

Involvement of CBF in the fine-tuning of litchi flowering time and cold and drought stresses.

Litchi (Litchi chinensis) is an economically important fruit tree in southern China and is widely cultivated in subtropical regions. However, irregular flowering attributed to inadequate floral induction leads to a seriously fluctuating bearing. Litchi floral initiation is largely determined by cold temperatures, whereas the underlying molecular mechanisms have yet to be identified. In this study, we identified four CRT/DRE BINDING FACTORS (CBF) homologs in litchi, of which LcCBF1, LcCBF2 and LcCBF3 showed a decrease in response to the floral inductive cold. A similar expression pattern was observed for the MOTHER OF FT AND TFL1 homolog (LcMFT) in litchi. Furthermore, both LcCBF2 and LcCBF3 were found to bind to the promoter of LcMFT to activate its expression, as indicated by the analysis of yeast-one-hybrid (Y1H), electrophoretic mobility shift assays (EMSA), and dual luciferase complementation assays. Ectopic overexpression of LcCBF2 and LcCBF3 in Arabidopsis caused delayed flowering and increased freezing and drought tolerance, whereas overexpression of LcMFT in Arabidopsis had no significant effect on flowering time. Taken together, we identified LcCBF2 and LcCBF3 as upstream activators of LcMFT and proposed the contribution of the cold-responsive CBF to the fine-tuning of flowering time.

Volatile Characterization of Lychee Plant Tissues (Litchi chinensis) and the Effect of Key Compounds on the Behavior of the Lychee Erinose Mite (Aceria litchii).

Herbivore-Induced Plant Volatiles (HIPVs) are volatile signals emitted by plants to deter herbivores and attract their natural enemies. To date, it is unknown how lychee plants, Litchi chinensis, respond to the induction of leaf galls (erinea) caused by the lychee erinose mite (LEM), Aceria litchii. Aiming to reveal the role of HIPVs in this plant-mite interaction, we investigated changes in the volatile profile of lychee plants infested by LEM and their role on LEM preferences. The volatile profile of uninfested (flower buds, fruit, leaves and new leaf shoots) and infested plant tissue were characterized under different levels of LEM infestation. Volatiles were collected using head-space-solid phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) analyses. Fifty-eight volatiles, including terpenoids, alcohols, aldehydes, alkanes, esters, and ketones classes were identified. Using dual-choice bioassays, we investigated the preference of LEM to uninfested plant tissues and to the six most abundant plant volatiles identified. Uninfested new leaf shoots were the most attractive plant tissues to LEM and LEM attraction or repellence to volatiles were mostly influenced by compound concentration. We discuss possible applications of our findings in agricultural settings.

Reduction of Pericarp Browning and Microbial Spoilage on Litchi Fruits in Modified Atmosphere Packaging

The pericarp browning and postharvest microbiological decay of litchi fruit (Litchi chinensis Sonn cv Kwai Mai) significantly reduce its commercial potential in the fresh market. In this study, different combinations of modified atmosphere packaging (MAP) were applied at 5 ± 1 °C based on the use of natural gases that are innocuous to human health and an alternative to commercially adopted sulfur dioxide (SO2) treatment. The results showed that control fruits, after 6 days of storage, begin to show the first symptoms of decay, revealed by the appearance of lesions and microbial infections determined by total mesophilic microorganisms and molds. This is not the case in the MAP-treated fruits and the MAP 3-treated (5% O2 + 20% CO2 + 75% N2) fruits that show the best results. The control fruits, moreover, turned completely brown by the end of the storage period. The MAP 3 treatment was the most effective in preventing browning and the loss of the red pericarp color and vitamin content and in maintaining acceptable SSC/TA levels and flavor. In addition, a microbiological analysis revealed that all the MAP-treated litchi fruits did not harbor undesirable microorganisms during the entire cold storage period. In conclusion, the MAP 3 conditions delayed pericarp browning and maintained the better organoleptic quality of litchi fruits.

Peronophythora litchii RXLR effector P. litchii avirulence homolog 202 destabilizes a host ethylene biosynthesis enzyme.

Oomycete pathogens can secrete hundreds of effectors into plant cells to interfere with the plant immune system during infection. Here, we identified a Arg-X-Leu-Arg (RXLR) effector protein from the most destructive pathogen of litchi (Litchi chinensis Sonn.), Peronophythora litchii, and named it P. litchii avirulence homolog 202 (PlAvh202). PlAvh202 could suppress cell death triggered by infestin 1 or avirulence protein 3a/resistance protein 3a in Nicotiana benthamiana and was essential for P. litchii virulence. In addition, PlAvh202 suppressed plant immune responses and promoted the susceptibility of N. benthamiana to Phytophthora capsici. Further research revealed that PlAvh202 could suppress ethylene (ET) production by targeting and destabilizing plant S-adenosyl-L-methionine synthetase (SAMS), a key enzyme in the ET biosynthesis pathway, in a 26S proteasome-dependent manner without affecting its expression. Transient expression of LcSAMS3 induced ET production and enhanced plant resistance, whereas inhibition of ET biosynthesis promoted P. litchii infection, supporting that litchi SAMS (LcSAMS) and ET positively regulate litchi immunity toward P. litchii. Overall, these findings highlight that SAMS can be targeted by the oomycete RXLR effector to manipulate ET-mediated plant immunity.

Species Complex of Leaf Roller Infesting Litchi (&lt;i&gt;Litchi chinensis&lt;/i&gt; Sonn.) In West Bengal with their Seasonal Incidence

An experiment was conducted at Fruit Research Station, Mandauri, Bidhan Chandra Krishi Viswavidyalaya with a view to rule out the leaf roller species complex associated with litchi (Litchi chinensis) in West Bengal. The result revealed that three species namely litchi leaf roller, Gatesclarkeana sp. (Lepidoptera: Tortricidae); leaf webber, Dudua aprobola Meyrick (Lepidoptera: Tortricidae); litchi leaf roller, Statherotis leucaspis Meyrick (Lepidoptera: Tortricidae) were associated with the crop and hence their seasonal incidence and interaction with abiotic factors have also been studied. Among the species Gatesclarkeana sp. was found least abundant and occasionally observed during fruiting season while Dudua aprobola observed only in copper leaf stage or in soft tender leaves. Statherotis leucaspis was observed as most dominant species in basin of West Bengal which has not yet been reported from the state. The pest remained very active from 26th standard meteorological week and continued upto 47th standard week. Interestingly the same pest was observed during panicle initiation stage to flowering stage, attacking the panicle (maximum 23.75%) which led direct yield loss.

Ectopic Expression of AGAMOUS-like 18 from Litchi (Litchi chinensis Sonn.) Delayed the Floral Organ Abscission in Arabidopsis

The regulation of abscission has a significant impact on fruit yield and quality. Thus, understanding the mechanisms underlying abscission, particularly identifying key genes, is critical for improving fruit crop breeding and cultivation practices. Here, to explore the key genes involved in litchi fruitlet abscission, the two closest homologs of AGAMOUS-like 15/18 (LcAGL15 and LcAGL18) were identified. During the litchi fruitlet abscission process, LcAGL15 expression was reduced, whereas LcAGL18 expression was increased at the abscission zone. The abscission of floral organs was unaffected by ectopic expression of LcAGL15 in Arabidopsis. Moreover, high expression of LcAGL18 significantly delayed the abscission process of floral organs, particularly the sepals. Overexpression of LcAGL18 in Arabidopsis consistently repressed the expression of abscission-related genes, including HAESA (HAE) and HAESA-LIKE2 (HSL2), and cell wall remodeling genes at the abscission zone. Furthermore, LcAGL18 was localized in the nucleus and acted as a transcriptional inhibitor. Collectively, these results suggest that AGL18 homologs have conserved functions in Arabidopsis and litchi, and that LcAGL18 might function as a key regulator in litchi fruitlet abscission.

How environmental conditions, phenological periods, and production endowment affect lychee yield

AbstractThe increasingly revealed effects of climate change threaten tropical fruit production. Considerable production loss and unstable yield has been observed in China and other regions with similar climate condition. Accordingly, this paper aims to explore the impacts of environmental conditions, phenological periods, and production endowments on a tropical fruit yield, namely lychee, by using the extended Cobb–Douglas model. Lychee (Litchi chinensis Sonn.) is chosen as the focus of this study given it is one of the most climate‐sensitive tropical fruits which have important contributions to the health, economy, and culture in South China. The growth‐span was divided into four phenological periods, namely: exposure period, heading period, flowering period and maturing period. A two‐way fixed effect model is employed for county‐level mixed‐frequency panel data. This data comprises lychee yield, environmental conditions (mean temperature, minimum temperature, and precipitation), production endowments (labor input, capital input, and technical input), and phenological periods in 39 main producing counties in China from 2011 to 2019. The key conclusions of interest are (1) higher minimum temperature results in larger lychee yield, (2) higher minimum temperature in the earlier phenological period has larger positive impact on lychee yield, and (3) higher growth in technical input causes lower lychee yield, and an explanation is provided. Heterogeneity analysis further implies various effects of the minimum temperature influencing lychee yield. The minimum temperature has a significant positive effect on lychee yield in non‐coastal and non‐western counties, especially in earlier phenological periods.

Storability and Linear Regression Models of Pericarp Browning and Decay in Fifty Litchi (Litchi chinensis Sonn.) Cultivars at Room Temperature Storage.

The primary cause for the limited shelf life of litchi fruit is rapid pericarp browning and decay. This study aims to evaluate the storability of 50 litchi varieties and establish a linear regression model for pericarp browning and decay based on 11 postharvest physical and chemical indices after 9 days of storage at room temperature. The results indicated that the average value of the browning index and decay rate significantly increased to 3.29% and 63.84% of 50 litchi varieties at day 9, respectively. Different litchi varieties showed different variations in appearance indicators, quality indicators, and physiological indicators. Furthermore, principal component analysis and cluster analysis revealed that Liu Li 2 Hao exhibited the highest resistance to storage, whereas Dong Long Mi Li, Jiao Pan Li, E Dan Li 2 Hao, and Ren Shan Li were not resistant. Stepwise multiple regression analysis further demonstrated that the factors were highly correlated with the decay index, with a partial correlation coefficient of 0.437 between the effective index and the decay index. Therefore, pericarp thickness, relative conductivity, pericarp laccase activity, and total soluble solids were significant indicators for the comprehensive evaluation of litchi browning and decay, and relative conductivity was the significant determinant causing fruit browning. These findings provide a new perspective on the sustainable development of the litchi industry.