Introduction

Litchi (Litchi chinensis), a high-value subtropical fruit from the Sapindaceae family, is prized for its vibrant red skin, juicy translucent aril, and a fine balance of sweetness and acidity. India, the second-largest producer of litchi globally, cultivates approximately 0.96 lakh hectares with a production of 0.746 million metric tonnes in 2021–20221. Despite its economic and nutritional importance, litchi productivity and fruit quality have become increasingly vulnerable to climatic variability, particularly unseasonably warm winters.

Naturally, litchi trees enter a natural period of reduced vegetative growth during cool winters, which is essential for synchronized flowering and fruit development2,3. The cultivar ‘Dehradun’—a prominent commercial variety grown extensively in northern India—is valued for its medium to large fruits, attractive bright-red skin, high pulp-to-seed ratio, and excellent aroma and sweetness. It typically ripens in early to mid-June and is highly preferred in fresh markets due to its superior organoleptic quality, though it is moderately sensitive to climatic fluctuations during flowering and fruit set. However, due to recent shifts in climatic patterns, growth of vegetative flush is uninterrupted through winter months, disrupting the natural allocation of carbohydrates and hormonal signals necessary for high-quality fruit development4. This phenomenon results in poor fruit set, low pulp percentage, and inferior fruit biochemical profiles—posing a major bottleneck for growers seeking high marketable yield5. This demands a targeted intervention to regulate vegetative growth while enhancing fruit quality through improved nutrient and hormone balance. Plant growth regulators (PGRs) like paclobutrazol (PBZ) have shown promise in curbing excessive vegetative growth by inhibiting gibberellin biosynthesis, thereby directing assimilate partitioning toward fruit development6. Simultaneously, micronutrients such as zinc (Zn) and boron (B) play pivotal roles in sugar metabolism, enzyme activation, and nutrient translocation, all of which are critical for fruit quality enhancement7,8,9,10.

While, PBZ and micronutrients like zinc and boron have been studied separately in various fruit crops, their combined use to manage vegetative growth and improve fruit quality in litchi especially under subtropical stress conditions has received little attention. With winters becoming milder due to climate change, the natural check on vegetative growth in litchi is weakening. In this context, PBZ could serve as a practical alternative to mimic that seasonal growth restraint. When used alongside zinc and boron, it may help rebalance plant physiology disrupted by shifting weather patterns, leading to improvements in key fruit quality traits such as size, pulp content, juice yield, sugar levels, and ascorbic acid. The study aims to (i) quantify improvements in fruit size, composition, and nutritional content, and (ii) determine the most effective treatment combinations for maximizing fruit marketability.

Material and methods

Site and design

The study was undertaken as a factorial field experiment during 2021–2023 on 20-year-old litchi trees (cv. Dehradun) at the Regional Horticulture Research and Training Station, Jachh, Kangra (32° 16′ 39.1″ N, 75°51′ 19.7″ E; 452 m AMSL) under Dr. YSP UHF, Solan. The site offers a subtropical climate with rainfall from July to August and soils characterized as deep, well-drained sandy loam with good organic matter content and slightly acidic reaction (pH 5.5–6.8)—conditions favorable for litchi growth and fruiting. Soil fertility is generally medium in available nitrogen and phosphorus, and adequate in potassium, with balanced micronutrient status supporting productive orchards. The experiment was laid out in a Factorial RBD with 15 treatments and 3 replications, detailed combinations are presented in Tables 1, 2 and 3. The study evaluated the combined effects of PBZ (Syngenta Cultar 23% SC) and micronutrients (Zinc and Boric acid AR grade) on fruit physical and biochemical traits applied at 2 different times. Trees were spaced 8 m × 8 m.

Table 1 Details of treatment factors used during the experiment.
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Table 2 Treatment combinations used during the experiment.
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Table 3 Treatment combination (PBZ = October application; Micronutrients = Feb application).
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Below are the 15 combinations generated from 2 levels of PBZ × 4 levels of micronutrients, T1 through T15 are highlighted due to significant responses across traits.

Vegetative parameters

Number of flushes

The number of flushes was determined visually by observing periods when a tree exhibited a noticeable increase in shoot growth. Each distinct period of active shoot emergence was counted as one flush. The total number of such growth events occurring during the observation period was recorded and referred to as the number of flushes.

Intensity of flushing

For measuring flushing intensity, each tree was divided into four quadrants. From each quadrant, ten shoots were selected randomly during a given flush, and the length of each shoot was measured in cm. The average shoot length from all selected shoots represented the intensity of flushing for that observation period.

Overall percentage of flushing

From the ten selected shoots on each side of the tree, the number of shoots actively flushing during a particular flush was counted. This procedure was repeated for each subsequent flush throughout the experiment. For each flush, the percentage of flushing was calculated as:

$${P}_{f}=\frac{{S}_{f}}{{S}_{t}}\times 100$$

where:

Pf = Percentage of flushing for a given flush

Sf = Number of flushing shoots observed

St = Total number of shoots observed

The overall percentage of flushing for a tree was obtained by averaging the flushing percentages across all recorded flushes:

\({P}_{overall}=\frac{\sum_{i=1}^{n} {P}_{fi}}{n}\)Poverall = Overall percentage of flushing for the tree

Pfi = Percentage of flushing in the ith flush

n = Total number of flushes recorded

Phenological observations (flowering metrics)

Flowering and panicle phenology were recorded throughout each season. Dates of the following events were recorded on each experimental tree and converted to day of year (DOY) for analysis:

  • Panicle emergence: DOY when 50% of tagged panicles in a tree were visibly emerged.

  • Flowering initiation (first flower opening): DOY when the first 10% of flowers on tagged panicles had opened.

  • Full bloom: DOY when ~ 80% of flowers on tagged panicles were open.

  • Duration of flowering: Full bloom DOY − Flowering initiation DOY (days).

  • Days from full bloom to harvest: Harvest DOY − Full bloom DOY.

  • Days from fruit set to maturity: Days between apparent fruit set and harvest (measured in days).

At the beginning of the season, 10 representative panicles per tree were tagged for phonological monitoring. Observations were recorded at 3–4 day intervals until harvest. For each tree, the mean DOY per metric (and standard error) was calculated across tagged panicles and pooled over the two seasons.

Definitions and notes

DOY (day of year) conversion standardizes calendar dates between seasons and simplifies statistical comparison. Where seasonal differences existed, pooled analysis accounted for year effect in ANOVA (see Statistical Analysis).

Fruits were harvest after development of red colour and were subjected to analysis for recording physiochemical parameters including fruit weight, aril weight, seed weight, pericarp weight, fruit length and width, reducing sugar content, non-reducing sugar content, TSS/ acid ratio and ascorbic acid content. Fruit physical traits were assessed using a sample of 10 fruits per replication. Fruit weight was measured with an electronic balance, while fruit length and breadth were recorded using a digital vernier calliper. Volume was determined via the water displacement method11, and pulp percentage was calculated based on pulp weight after removing peel and seeds.

Biochemical traits included total soluble solids (TSS), measured in °Brix using a Labart Milwaukee MA871 refractometer, and titratable acidity, estimated by titration with 1N NaOH using phenolphthalein, and expressed as percent malic acid.

$$TA\left(\%\right)=\left(\frac{T \times N \times V \times We}{Va \times Vs \times 1000}\right) \times 100$$

TA- Total titratable acidity (%); T = titratable value; N = Normality of NaOH; V = Volume made up; We = Equivalent weight of acid (66); Va = volume of aliquot taken; Vs = volume of sample taken.

Estimation of Sugars and TSS/Acid Ratio: Total sugars were estimated following the method described by Ranganna12. A mixture of Fehling’s solutions A and B was titrated against the sample solution until a brick-red precipitate appeared, indicating the endpoint. The total sugar content was calculated using the formula:

$$\text{TS}\left(\text{\%}\right)=\frac{[\text{Dilution factor}\left(0.05\right)\times\text{Dilution}\left(100\right)] }{(\text{Titrate value}\times\text{volume of sample taken})}\times100$$

Reducing sugars were estimated using a similar titration procedure, and calculated using the formula:

$$\text{RS}\left(\text{\%}\right)=\frac{\text{Dilution factor}\left(0.05\right)\times\text{Dilution}(100))}{\left(\text{Titrate value}\times\text{volume of sample take }\right)}\times100$$

Non-reducing sugars were obtained by subtracting the reducing sugar content from the total sugar content and multiplying the result by 0.95:

$$\text{Non}-\text{reducing Sugars}\left(\text{\%}\right)=\left(\text{TS}-\text{RS}\right) \times 0.95$$

TSS/acid ratio was calculated by dividing the total soluble solids (TSS) by the titratable acidity:

$$\text{Tss}:\text{Acid}=\left(\frac{\text{TS}}{\text{Titrtable acid}}\right)$$

Ascorbic acid content was estimated using the 2, 6-dichlorophenol indophenol titration method described by Rangana11 and expressed as mg/100 g of fruit aril.

$$\text{Ascorbic acid}(\text{mg}/100\text{g})=\frac{(\text{Titrate reading}\times\text{dye factor}\times\text{dilution}\times100)}{(\text{aliquat of extract}\times\text{weight of sample taken})}$$

Statistical analysis: All the above-mentioned observations recorded during field experimentation and lab analysis were subjected to statistical analysis of Variance for FRBD. Significance and non-significance of the variance due to different treatment application was determined using the respective F value according to methods described by Gomez and Gomez13. Also, Significance of treatment effects was tested at p < 0.05 using ANOVA; CD values were calculated where applicable.

Recommendations: To identify the most effective treatment combinations, a multi-criteria decision analysis (MCDA) approach was employed14. Key fruit quality traits—both physical (fruit weight, pulp percentage, juice content) and biochemical (TSS, total sugars, reducing sugars, TSS:acid ratio, and ascorbic acid)—were selected as evaluation parameters. Each parameter was assigned a weight based on its relative importance to marketability and nutritional value, summing to a total of 100% (Table 4). Trait data were normalized by dividing the observed value by the maximum value for that trait across all treatments. A weighted score for each trait was calculated by multiplying the normalized score by its assigned weight. The total performance score (TPS) for each treatment was obtained by summing its weighted scores across all traits. Treatments were ranked based on TPS to identify those with the highest overall impact on fruit quality. This approach ensured objective, quantitative assessment of treatment efficacy and supported statistical interpretation of treatment performance under subtropical field conditions. Score = (Trait value / Best value) × Trait Weight.

Table 4 Scoring basis for assessment of best treatment for litchi production.
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Results and discussion

Impact of PBRs and micronutrients on vegetative flushing and flowering phenology

The Table 5 present the pooled data observed over a period of two years. The analysis of data revealed that the number of flushes and intensity of flush were not significantly influenced by the combined treatments, however if observed individually it was observed that use of PBZ presented significant difference with in number of flushes, length of flush (Intensity of flush) this indicate that on paclobutrazol (PBZ) affected while PBZ and micronutrient applications did not alter the basic flushing frequency or shoot elongation rate under the given climatic conditions. The major reason for this type of results was that application of PBZ was done in month of October while micronutrients were applied in the month of February. The data related to flush growth was recorded in December due to which the effect of micronutrient application was not visible. However, the overall percentage of shoots flushing varied significantly. The highest flushing percentage (48.2%) was recorded in T15 (control), which was statistically at par with T12 (45.4%), T14 (46.5%), and T11 (41.8%), while the lowest values (31.1–36.5%) were noted in PBZ-treated plants such as T10, T5, and T2. This reduction in flushing percentage in PBZ-applied treatments suggests effective suppression of vegetative growth due to gibberellin biosynthesis inhibition, thereby conserving assimilates for reproductive development. So these effects help the betterment of the trees in case of fruit quality.

Table 5 Impact of treatment combination on fruit physical parameters.
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No significant differences were observed in days to panicle emergence, days to flower initiation, duration of flowering, or duration from full bloom to harvest, indicating that PBZ and micronutrient combinations did not markedly advance or delay the onset or length of these phenological stages.

Contrastingly, duration from fruit set to harvest showed a significant response. The longest duration (76.0 days) was recorded in the untreated control (T15), followed by T5 and T6 (72.7–73.0 days), whereas the shortest duration (68.7 days) was observed in T2 (PBZ 50 ppm + Boric acid 1.0%). The reduction in the fruit development period under PBZ-based treatments can be attributed to more efficient carbohydrate partitioning and improved sink strength, leading to quicker attainment of physiological maturity.

The prior discussed results shows PBZ effectively reducing the percentage of shoots flushing (31–36%) compared to the control and micronutrient-only treatments (41–48%), although the number of flushes and flush length did not differ, suggesting PBZ restricted flush extent rather than frequency. This presents PBZ’s role as a gibberellin biosynthesis inhibitor effectively suppressing internode elongation, producing compact shoots and reducing vegetative sink competition, thereby favoring reproductive growth6,19. In contrast, foliar Zn or B alone did not affect flushing, consistent with their roles in metabolic and reproductive functions rather than vegetative suppression9. Flowering phenology was largely unaffected, but PBZ treatments shortened the fruit set–to–harvest period by 5–8 days, likely due to altered hormone balance and reduced gibberellin levels, which can accelerate maturation by releasing the ethylene-mediated ripening pathway30. PBZ’s mode of action—blocking ent-kaurene oxidation—reduces active GA, increases abscisic acid, and shifts carbohydrate allocation to reproductive sinks, potentially raising the cytokinin-to-GA ratio and enhancing the rate of fruit development31. Zinc and boron, though not affecting vegetative flush, are critical for pollen viability, pollen-tube growth, enzyme activation, and carbohydrate transfer to developing reproductive structures, with deficiencies linked to reduced flowering and fruit set7. These findings are consistent with earlier litchi studies showing PBZ reduces flushing without delaying bloom while enhancing flowering intensity19 and with broader fruit crop evidence that GA inhibition and micronutrient management can jointly improve reproductive performance under subtropical conditions.

PBRs and micronutrients impacting Physical parameters of fruit

The data presented in Table 6 highlights various physical parameters of fruit under where, Treatment T9 (PBZ @ 100 ppm followed by ZnSO4 @ 1.0%) yielded the longest (36.54 mm) and breadth (35.01 mm) fruits, while trees under T15 (control) produced the fruits having shortest length (20.50 mm) and breadth (25.89 mm) fruits. This significant increase in size can be attributed to the growth-regulating effect of PBZ, which optimizes carbohydrate and nutrient allocation towards the fruit by controlling excessive vegetative growth. Weight and Volume: Treatment T4 had the heaviest fruits (23.70 g) and highest volume (22.70 mm3), while T15 had the lightest fruits (13.45 g) and the smallest volume (11.69 mm3). Treatments T1, T3, T8, T9, T14, T13 and T12 were found having statistically similarity to T4, these treatments can be considered having similar weight and volume and were better than control. This weight and volume increase under PBZ and ZnSO₄ treatments reflects a more effective translocation of assimilates to the fruit, enhancing fruit cell division and expansion. Pulp Percentage: The highest pulp percentage was observed in treatment T1 (73.73%), with other treatments (T3 and T4) also exhibiting similar high pulp percentages. In contrast, treatment T15 had the lowest pulp percentage (64.68%). Peel Percentage: Control (T15) exhibited maximum peel percentages of 15.64%, while treatment T1 had the lowest peel percentage (8.42%). Treatment T3, T4, T8, T13 and T14 were found statistical parity to minimum peel percentage. The low peel percentage demonstrate effective nutrient utilization and reduced non-edible fractions, which are preferable for marketable fruit quality. This trend suggests that PBZ treatments may optimize pulp production by modulating the skin-to-pulp ratio. Juice Percentage: The Maximum juice content was found in treatment T4 (84.53%), whereas control (T15) had the minimum juice percentage (56.97%). Overall, treatments T3, T4, T5, T8, T9, T13 and T14 showed similarity in juice content T4, making them more favourable for juice extraction. The higher juice yield under T4 and similar treatments may also result from optimized water and nutrient uptake facilitated by ZnSO₄, which improves overall fruit texture and juiciness.

Table 6 Impact of treatment combination on fruit physical parameters.
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The improved fruit quality attribute about fruit morphology and internal quality traits under PBZ and ZnSO₄ treatments can be attributed to their synergistic influence on plant physiological processes. Basically, increase in fruit length and width is associated with enhanced cell division and expansion15, facilitated by PBZ-induced source–sink regulation and zinc-mediated auxin synthesis. Improved fruit weight and volume reflect more effective assimilate partitioning, where PBZ limits vegetative growth and redirects carbohydrates to reproductive organs6, while zinc activates enzymes involved in sugar metabolism and supports photosynthetic efficiency16. Higher pulp percentage corresponds to enhanced aril development, due to hormonal modulation and efficient sugar translocation. Conversely, reduced peel percentage under these treatments indicates optimized nutrient utilization, where assimilates are preferentially allocated to pulp tissue, and zinc contributes to balanced cell wall development and reduced non-edible tissue. The increase in juice content is likely due to improved osmotic balance, water uptake, and sugar accumulation, with zinc enhancing membrane transport and sugar-loading capacity, and PBZ supporting overall sink strength17. These physiological mechanisms collectively support the observed improvements in fruit size, weight, pulp-to-peel ratio, and juice yield. Similar findings were observed in litchi cv. Shahi18,19 and China20 on using of PBZ improved fruit size of litchi. In Harumanis mango using PBZ resulted in enhancement of fruit physical characters21.

PBRs and micronutrients impacting Biochemical parameters of litchi

The results presented in Table 7 shows that foliar applications of PGRs and micronutrients had significant effect on biochemical properties of the fruits. The highest reducing sugars (13.10%) were recorded with T9 (PBZ @100 ppm followed by ZnSO4 @ 1.0%). The highest TSS was recorded with foliar application of T4 PBZ @50 ppm followed by ZnSO4 @ 1.0%) (21.40 oB). Contrastingly fruits obtained from tree under (T15) control exhibited lowest TSS content of (17.50 oB) over a period of 2 years.

Table 7 Impact of foliar application of PBZ, ZnSO4 and Boron on biochemical parameters of litchi fruits.
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Reducing Sugars: The highest reducing sugars (13.10%) were recorded with T9 (PBZ @100 ppm), followed by T14 (11.86%) and T3 (11.83%). Non-Reducing Sugars: The highest non-reducing sugars were observed in T2 (4.29%), followed by T13 (4.30%) and T4 (4.02%). Total Sugars: The highest total sugar content (15.80%) was recorded with T9 (PBZ @100 ppm followed by ZnSO4 @ 1.0%), followed by T4 (15.22%) and T8 (15.15%). Total Soluble Solids (TSS): The highest TSS was recorded with T4 (21.40°B), followed by T1 (20.97°B) and T3 (20.67°B). In contrast, fruits obtained from trees under T15 (control) exhibited the lowest TSS content of (17.05°B). Titratable Acidity: The lowest titratable acidity (0.29%) was found in T2, followed by T8 (0.30%). In contrast, T9 showed the highest titratable acidity (0.36%). TSS: Acid Ratio: The highest TSS: acid ratio was recorded in T4 (74.51), followed by T2 (70.50), while T15 (control) recorded the lowest TSS ratio (50.43). Ascorbic Acid Content: The highest ascorbic acid content (36.50 mg/g) was recorded with T14, followed closely by T9 (36.11 mg/g), while the lowest ascorbic acid content (24.60 mg/g) was observed in T5. The above mention results can be attributed their physiological impacts on litchi fruit metabolism. Paclobutrazol (PBZ) functions as an anti-gibberellin that reduces vegetative growth by inhibiting gibberellin biosynthesis, redirecting more carbohydrates and photosynthates toward reproductive organs rather than vegetative tissues. This diversion results in higher accumulation of sugars in the fruit, increasing reducing and total sugar content. Additionally, ZnSO₄ plays a critical role as a cofactor for numerous enzymes involved in carbohydrate metabolism, such as dehydrogenases, which catalyse sugar synthesis and storage within the fruit. Zinc’s involvement in photosynthesis and chlorophyll synthesis enhances the plant’s energy efficiency, leading to increased sugar synthesis that contributes to higher TSS values22. Furthermore, zinc improves root development and nutrient uptake23,24, enabling better assimilation and mobilization of nutrients required for fruit development and quality enhancement. Higher ascorbic acid levels observed in treatments with PBZ and ZnSO₄ can be linked to zinc’s role in antioxidant enzyme activation, which boosts ascorbate synthesis as part of the plant’s response to oxidative stress25,26. These physiological effects, achieved through carefully timed foliar applications of PBZ and ZnSO₄, thus create a favourable metabolic environment that enhances both the nutritional and organoleptic quality of litchi fruit, making these treatments valuable for optimizing fruit sweetness, acidity.

On using ZnSO4 at 1% concentration significantly enhance the total soluble solids (TSS) content in fruit due to its multiple roles in plant physiology. Zinc acts as a vital cofactor for enzymes involved in carbohydrate metabolism, leading to increased sugar synthesis and accumulation in the fruit, which directly raises TSS27. Additionally, zinc is crucial for chlorophyll synthesis28, improving photosynthesis efficiency29 and, consequently, carbohydrate production, with a portion of these sugars being transported to the fruit. Enhanced root development and nutrient absorption from zinc application contribute to overall plant health, resulting in better fruit quality and higher concentrations of sugars and other soluble solids8. Furthermore, zinc delays fruit senescence by stabilizing cell membranes and reducing oxidative stress, helping fruits retain sugars longer. Zinc also plays a role in the synthesis of auxins, essential hormones for fruit growth and development, thereby improving sugar translocation into fruits and boosting TSS levels. Together, these physiological effects make ZnSO₄ foliar applications a valuable practice for improving TSS and fruit quality.

Identification of best treatment combination

After thorough analysis of results, it was found that using different PBRs and Micronutrients as combination resulted in providing multiple treatments as superior. In order to find the best treatment out of all and refer as a recommendation it was necessary to provide the weight to different treatments which has been already presented. On using this method, the data obtained is presented in Table 8.

Table 8 Evaluation of best treatment on the basis of MCDA approach.
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On the basis of above method T4 (Paclobutrazol (PBZ) @ 50 ppm + Zinc Sulphate (ZnSO₄) @ 1.0%) was found having highest MCDA Score of 97.224 and fruits of T4 have superior character than other applied treatments.

To further visualize the comparison a radar plot (Fig. 1) was created between T4 and T15 (control)

Fig. 1
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Radar plot comparing Treatment T4 (blue) and Control T15 (red), highlighting T4’s superior performance in key fruit quality traits, especially juice content, TSS, TSS:acid ratio, and total sugars.

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PCA analysis

The Principal Component Analysis (PCA) was conducted on normalized pooled trait data using co-relation matrix method. The biplot (Fig. 2) provides a multidimensional overview of the treatment responses based on pooled physical and biochemical traits of litchi. The first two principal components (PC1 and PC2) account for a substantial proportion of the total variance—PC1 explains approximately 45–55%, and PC2 adds another ~ 20–25%, cumulatively capturing over 70–75% of the total data variability. Finally, PC1 and PC2 accounted for 52.3% and 21.8% of total variance, resulting in cumulative 74.1% of variability in fruit quality trait within different treatment.

Fig. 2
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Principal Component Analysis (PCA) biplot showing separation of treatments based on pooled fruit quality traits. Treatments T4, T9, and T14 cluster away from control (T15), indicating superior performance across multiple traits.

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The spatial distribution of treatment groups in the PCA biplot revealed clear clustering patterns that distinguish the control (T15) from the high-performing treatments (T4, T9, and T14). Treatments T4 and T9 were positioned far from the control along the first principal component (PC1), driven by strong positive loadings for key fruit quality attributes such as fruit weight, juice percentage, total sugars, and the TSS:acid ratio. This separation reflects a markedly improved fruit quality profile in these treatments compared to the untreated control. Treatment T14 clustered in close proximity to T9, suggesting a similar biochemical composition. This treatment was particularly associated with higher levels of ascorbic acid and reducing sugars, indicating a nutrient-dense fruit profile beneficial for both nutritional and sensory appeal. In contrast, the control treatment (T15) was located on the opposite end of PC1, representing the lowest performance across most evaluated traits. Its position in the biplot is indicative of lower TSS, sugar content, fruit weight, and other critical quality parameters.

Overall, the PCA clearly illustrates the significant impact of foliar PBZ application, especially when combined with ZnSO₄ or boron, on modifying trait expression in litchi fruits. The distinct clustering of T4, T9, and T14 away from the control confirms the effectiveness of these treatments in enhancing fruit quality and mitigating the adverse effects of climatic stress. These PCA patterns align closely with MCDA rankings, confirming the multidimensional superiority of T4, T9, and T14.

Conclusion

The present study clearly demonstrates that the combined foliar application of paclobutrazol (PBZ) and micronutrients, particularly Zinc Sulphate (ZnSO₄), significantly enhances both the physical and biochemical quality attributes of litchi fruits under subtropical conditions increasingly impacted by climate variability. PBZ effectively regulated vegetative growth, leading to improved allocation of assimilates towards fruit development, while ZnSO₄ improved nutrient uptake, sugar metabolism, and antioxidant activity. Among the treatment combinations, PBZ @ 50 ppm followed by ZnSO₄ @ 1.0% (T4 and T9) consistently produced the most favourable results in terms of fruit size, pulp and juice percentage, total soluble solids, sugar accumulation, and ascorbic acid content. While T4 (PBZ @ 50 ppm + ZnSO₄ @ 1%) was the top performer overall based on MCDA scores, T9 (PBZ @ 100 ppm + ZnSO₄ @ 1%) also showed high performance, especially for reducing sugars and ascorbic acid. Both levels showed promise but varied in trait emphasis. These synergistic effects not only mitigated the negative impacts of unseasonal vegetative flushing but also enhanced marketable yield and fruit nutritional value. Overall findings direct towards conclusion that integrated use of growth regulators and micronutrients can serve as a viable strategy for improving yield quality under climate-challenged subtropical conditions. Highest BC ratio was 1.15 (Paclobutrazol 50 ppm + ZnSO4 @1%) while control recorded ratio of 0.68 only. So, Using PBZ 50 ppm in month of October along with use of Zinc sulphate @ 1% at panicle emergence stage as promising, climate-resilient intervention for sustainable and profitable litchi cultivation in subtropical regions.