Impact of pre-harvest methyl jasmonate applications on shelf-life improvement of strawberry ( Fragaria × ananassa Duch.) under semi-arid condition of Bundhelkhand,India

Abstract

The experiment was conducted to assess the impact of pre-harvest methyl-jasmonate (MeJA) sprays on fruit quality retention and storability of strawberry under semi-arid condition of Bundhelkhand, India. MeJA was sprayed on strawberry plants at 2.5–10 μM concentration during 2023 and 2024 in four different growth phases [45, 45 + 60, 45 + 75 and 45 + 90 days after planting (DAP)]. After harvesting, the fruit were stored at 8°C temperature with 85–90% relative humidity. Two pre-harvest MeJA sprays at 45 + 75 DAP with 5.0–10 μM concentration had minimum physiological weight loss (2.61–2.65%) with least spoilage (10.00%) in the stored strawberry fruit at 9^th day of storage. Applications of same concentration of MeJA at 45 + 75 DAP was also found significant for retaining the biochemical attributes of the stored strawberry fruit till 9^th day of storage; although a sharp decline in fruit quality attributes were observed in control fruit from 6^th day onward. Peroxidase and polyphenol oxidase activity in the fruit on 9^th day of storage was also recorded minimum under two pre-harvest MeJA sprays at 45 + 75 DAP with 5.0–10 μM concentration with maximum catalase and phenylalanine amino-lyase activity. Hence, it can be recommended that pre-harvest applications of 5.0 μM methyl jasmonate at 45 and again at 75 DAP followed by refrigerated storage of ripe strawberry fruit is effective for improving the shelf life of strawberry cv. ‘Winter Dawn’ up to 9 days under semi-arid ecosystem of Bundhelkhand, India.

Keywords

antioxidant activity methyl jasmonate oxidative enzymes storage behaviour strawberry

Introduction

Strawberry (Fragaria × ananassa Duch.) belongs to Rosaceae family and growing throughout the world intensively. The popularity of this fruit is mainly due to its organoleptic taste and high nutritional values.¹ In addition, the ripe strawberry fruit is rich in flavour and aroma that makes it excellent in quality and appearance. It is consumed both as fresh fruit and as processed products. Many people all over the world use this fruit in their daily diet since they are rich in vitamins and minerals in addition to their delicious flavour. Moreover, it is also rich in polyphenols, antioxidant compounds that exhibit a remarkably high scavenging activity toward chemically generated radicals. Hence, the regular consumption of strawberry is helpful to reduce the risk of several serious illnesses in human being, including type II diabetes, cardiovascular disease, and malignant (cancerous) tumours.²

Because of high nutritional as well as medicinal importance, the demand of strawberry in the market is also increasing day by day. Conventionally, it is the crop of fertile areas of temperate region worldwide. But with the increasing demand, now its cultivation is also expanded in the foothills and in the subtropical and semi-arid regions too. The farmers of these regions are adopting commercial cultivation of strawberry at a faster rate due to its quicker growth and significantly higher returns per unit area at shortest possible time-period, as the harvesting of strawberry is completed within 6 months of planting.

Being non-climacteric in nature, the harvesting of this fruit is done when it reaches to full ripening on the plant itself. But the main concern with strawberry is its high perishable nature and vulnerability to different pathological decay under storage condition because of its fragile pericarp and high moisture content of the fruit.³ It ultimately limits the shelf-life of the crop significantly. Hence, it is a major challenge for the strawberry growers worldwide to improve the shelf life of the crop without any deterioration in the quality attributes to make it more remunerative in the market for longer period.

There is a wide range of plant growth regulators, which play significant role to improve the shelf life of different fruit crops.^4–10 Among these, Jasmonic acid (JA) and its derivative, methyl jasmonate (MeJA), are responsible for altering a number of physiological functions within the plant system resulting increased plant defence mechanisms such as antioxidant defence against abiotic stresses and diseases¹¹ which in turn is very helpful for increasing the overall shelf life of the fruit by preventing the post-harvest decay losses. Basically, MeJA is a cyclopentanone-based molecule, considered to be an important plant hormone that can regulate communications within the plants because of its volatile nature and capacity to penetrate through biological membranes¹²; hence play vital role for altering different physiological processes at a faster rate. In addition, it also play significant role to regulate the fruit growth and ripening process^13,14 by regulating the expression of different ripening genes.¹⁵ It has also been shown that applications of MeJA improves antioxidant compounds, reduces deterioration, and maintains fruit quality attributes significantly.¹⁶ In addition, pre-harvest MeJA treatment increases the concentrations of phenolic and anthocyanins in different fruit crops during their ripening,¹⁷ resulting significant improvement in red colour development on the fruit¹⁸ as well as their retention after harvesting. Hence, it can be hypothesised that applications of MeJA is helpful for the improvement of shelf life and retention of fruit quality of strawberry significantly for a longer period of time. However, the literatures on the effect of pre-harvest applications of methyl jasmonate on retention of fruit quality attributes and shelf life improvement in strawberry in very scanty.

Further, applications of any chemical after harvesting of the fruit are recommended to avoid because of to its high residual effect. In most of the cases, post-harvest applications of different chemicals remains within the fruit even during its final consumption and sometimes it is beyond the maximum residual limit (10 ppm) permitted in countries like Australia, Europe, Japan etc. Such condition, not only alter the taste of the fruit but also causes health hazards to the ultimate consumers.¹⁹ Therefore, it is very important to adopt the pre-harvest sprays of any chemicals instead of its post-harvest applications. Hence, the present research work was formulated with the thought that the pre-harvest applications of methyl jasmonate may improve the shelf life of strawberry fruit significantly without any deterioration in fruit quality attributes.

Materials and methods

The in vitro raised strawberry (Fragaria × ananassa Duch.) plants of cultivar ‘Winter Dawn’ were used under the present experiment. Healthy plants with uniform growth and free from any injuries as well disease infestation were planted in the raised bed (15 cm in height, 1.5 m in length, and 1.0 m in width) of Fruit Demonstration Unit, Rani Lakshmi Bai Central Agricultural University, Jhansi, India (25°30′44″ North latitude to 78°32′31″ East longitude) during mid-October of both the consecutive years (2023 and 2024) at 30 × 45 cm spacing in zig-zag pattern.

Fifteen days before planting, beds were prepared by adding 20 kg farmyard manure per bed. NPK was applied to the bed five days before planting at 10:6:10 g/plant as basal dose and black polythene mulch (30 microns) was placed over the bed one day before planting of strawberry plants. Thereafter, the entire plantation was irrigated through drip irrigation (emitter discharge rate – 2 liters per hour) and plant protection measures were adopted uniformly as per the need of the crop.

Preparation of methyl jasmonate solution and its applications

One day prior to its applications, the concentrated methyl jasmonate was first dissolved in pure (99.9%) ethanol and then distilled water was added to it to prepare one litre stock solution. On the day of its applications, the working solutions of 2.5, 5.0 and 10.0 μM were prepared from this stock solution. These different concentrations of methyl jasmonate solution were sprayed on the experimental strawberry plants at 45 days after planting (DAP) (single sprays); 45 + 60 DAP (2 sprays); 45 + 75 DAP (2 sprays); 45 + 90 DAP (2 sprays) at 500 ml/plant. Distilled water was sprayed on the plants under control instead of methyl jasmonate solution.

Post-harvest handling

When the fruit reaches to its full ripening (as the colour of entire fruit surface completely turned into red), they were harvested manually by hand and brought to the laboratory. After removing the field heat from the harvested fruit by spreading them on the laboratory slab for 30 min, they were packed in perforated plastic boxes of 10 cm length, 10 cm breadth and 5 cm height with four holes of 0.5 cm diameter each at the upper part of the box. Each box had 330 cc spaces to keep the fruit inside. After packing the fruit in the boxes, they were stored in the frost free, 308 liters capacity refrigerator (Model: GL-C322KPZY/2021; Make: LG) having fixed temperature of 8°C and relative humidity of around 85–90%. The fruit were stored in the refrigerated condition for 12 days.

Observations recorded

Under laboratory condition, all the parameters were estimated at 3 days interval during the entire storage period. However, on 12^th day of storage, maximum fruit were decayed irrespective of treatment variation (Figure 1). Hence, we have estimated all the parameters of stored strawberry fruit till 9^th days of refrigerated storage.

Figure 1.

Effect of pre-harvest methyl jasmonate application on decay of ripe strawberry fruit cv. ‘Winter Dawn’ under refrigerated condition.

Physiological loss of weight

The weight of individual fruit under each treatment was taken through electronic weighing balance on the day of harvesting as initial weight of fruit and again during the entire storage period (on 3^rd, 6^th and 9^th day of storage) as final weight of fruit. Thereafter, physiological loss of weight (PLW) was estimated using the formula²⁰

PLW (%) = \frac{Initial weight - final weight}{Initial weight} \times 100

Decay loss

Estimation of decay loss was done based on the visual observation of rotting symptom on individual fruit, irrespective of severity and was estimated using the formula²¹

Decay loss (%) = \frac{Number of decay fruit}{Total number of fruit} \times 100

Fruit biochemical attributes

Total soluble solids (TSS) present in the fruit was determined at ambient room temperature with the help of digital refractometer (Model: H196801 ; Make: Hanna), following the procedure outlined by Ranganna.²² To extract the juice, a small piece of the fruit was crushed manually in a muslin cloth and a drop of the extracted juice was placed on the cleaned surface of the refractometer. Then this reading of TSS was corrected for temperature variations at 20 °C using International Temperature Correction Table.²³

Titratable acidity of the fruit was determined in accordance with the titration method outlined by Ranganna.²² Two gram fruit was crushed and homogenized in 50 ml distilled water and then filtered with filter paper. Then that filtrate was titrated with 0.1 N sodium hydroxide (NaOH) solution using phenolphthalein 1% solution as indicator.

Total sugar content was determined following the methodology of Lane and Eynone.²⁴ Ten gram fruit sample was crushed properly through pestle and mortar and transfer in a 500 ml volumetric flask. Therefore, distilled water (100 ml), lead acetate solution (2 ml) and potassium oxalate solution (1.9 ml) was added to it and final volume up of 250 ml was made with distilled water. Then the solution was filtered through filter paper and 50 ml filtrate was taken in a 100 ml volumetric flask. After adding 5 ml concentrated HCl to that filtrate solution, the mixture was kept at room temperature for 24 h. After completion of 24 h, phenolphthalein indicator (2 drops) and NaOH solution (40%) was added into it until the colour of the solution turn to pink. Then, 0.1 N HCl was added drop-by-drop to it to make the pink colour disappear and the obtained solution was taken in the burette for titration. Mean while, Fehling solution A and B (5 ml each) were mixed with distilled water to get a final volume of 50 ml and 1–2 drops of methylene blue solution was added to it and the mixture was boiled on hot plate. The titration of this boiling solution was done against the filtrate at the boiling point till the appearance of brick red colour of the solution.

The ascorbic acid present in the fruit was estimated following the methodology described by Jones and Hughes²⁵ using 2, 6-dichlorophenol indophenol dye as main reagent. Two gram fruit sample was crushed in 3% solution of metaphosphoric acid. The obtained solution was then diluted to 100 ml using the same solution (3% metaphosphoric acid) and 10 ml was taken for titration with 2, 6-dichlorophenol indophenol dye until a persistent pink colour was appeared.

Total anthocyanin content of strawberry fruit was estimated following the protocol outlined by Ranganna.²² One gram fruit sample was crushed in pestle and mortar using 10 ml ethanolic HCl solution (comprising 95% ethanol along with 1.5 N HCl in 85:15 ratio) and stored overnight at 4°C in a refrigerator. In the next morning, the mixture was filtered through Whatman No. 1 filter paper and the volume of the filtrate was adjusted to 20 ml using ethanoic HCl. Finally the absorbance of that solution was observed in UV–Vis double beam spectrophotometer (Model: UV Plus; Make: Motras Scientific Instruments) at 535 nm wavelength.

Antioxidant activity was estimated through Cupric Reducing Antioxidant Capacity (CUPRAC) assay.²⁶ One gram fruit sample was crushed in 10 ml ethanol (80%) and centrifuged at 10,000 rpm for 20 min at 4°C temperature. Thereafter, supernatant was collected and 1 ml each of copper chloride solution (10⁻² M), neocuproine (7.5 × 10⁻³ M) and ammonium acetate buffer (1 M, pH 7.0) was added to 100 µl supernatant and the final volume of the solution mixture was adjusted to 10 ml using distil water. Then, after keeping that solution to room temperature for 1 h, the absorbance was observed in UV–Vis double beam spectrophotometer (Model: UV Plus; Make: Motras Scientific Instruments) at 450 nm wave length.

Enzymatic activity

For estimation of polyphenoloxidase (PPO), peroxidase (POD) and catalase (CAT) activity, the enzyme extract from fruit sample was prepared as per the methodology described by Chongchatuporn et al..²⁷ One gram strawberry fruit was crushed in 20 ml potassium phosphate buffer (50 mM, pH 7.0) having 1% polyvinyl-pyrrolidone (w/v) in insoluble form. After crushing, the crushed sample was centrifuged for 20 min (4 °C) at 14000 rpm and the obtained supernatant was separated and stored at 4 °C for further use as crude enzyme. Similarly, for phenylalanine ammonia-lyase (PAL) activity, enzyme extract was prepared by crushing one gram strawberry fruit in 20 ml sodium borate buffer (100 mM, pH 8.0) containing 50 mM β-mercaptoethanol, 1% polyvinyl-pyrolidone and 1 mM EDTA solution.²⁸ After crushing, the crushed sample was centrifuged for 20 min (4 °C) at 14000 rpm and the obtained supernatant was used for enzyme assay.

For the estimation of PPO activity, 0.2 ml crude enzyme extract was mixed with 2.8 ml catechol solution of 20 mM concentration, prepared in sodium phosphate buffer (0.01 M; pH 6.8).²⁹ Then the increasing absorbance of that solution was observed for 3 min in a UV-Vis double beam spectrophotometer (Model: UV Plus; Make: Motras Scientific Instruments) at 410 nm wavelength. Each 0.1 unit change in absorbance value per min is considered as one unit of enzyme activity.

For the estimation of POD activity, 0.05 ml enzyme extract was mixed with 2.75 ml phosphate buffer (50 mM; pH 7.0), 0.1 ml H₂O₂ (0.1%) and 0.1 ml guaiacol (4%) solution.³⁰ Then the increasing absorbance of that solution due to guaiacol was observed for 2 min in a UV-Vis double beam spectrophotometer (Model: UV Plus; Make: Motras Scientific Instruments) at 410 nm wavelength. Each 0.1 unit change in absorbance value per min is considered as one unit of enzyme activity.

For the estimation of CAT activity, 5 µl enzyme extract was mixed with 1.5 ml potassium phosphate buffer (100 mM, pH 7.0) and 0.5 ml H₂O₂ (75 mM) and the volume of that solution was adjusted to 3 ml using distilled water.²⁸ Then the decreasing absorbance of that solution was observed for 1 min in a UV-Vis double beam spectrophotometer (Model: UV Plus; Make: Motras Scientific Instruments) at 240 nm wavelength.

For the estimation of PAL activity, 0.1 ml enzyme extract was mixed with 2.9 ml sodium borate buffer having 3 mM L-phenylalanine (0.1 M, pH 8.0).³¹ Then this mixed solution was incubated for 60 min at 37°C. Thereafter, the increasing absorbance of that solution due to trans-cinnamate formation was observed at 290 nm wavelength in UV–Vis double beam spectrophotometer (Model: UV Plus; Make: Motras Scientific Instruments) at 1 h interval. Each 0.01 unit increase in absorbance value per hour is considered as one unit of enzyme activity.

Statistical analysis

The entire experiment was laid on Factorial Randomized Block Design (FRBD) with two factors – the concentrations of methyl jasmonate (MeJA) (factor 1) and the growth stages of strawberry plants for the applications of MeJA (factor 2). Each treatment was replicated for three times under this experiment. Further, under each replication, five fruit were randomly chosen for the estimation of individual parameter. The experiment was conducted for two consecutive years (2023 and 2024) and the average value for individual parameter was analyzed statistically considering critical difference (CD) at 5% level of significance. Statistical analysis software (SAS 9.3; SAS Institute, Cary, NC, USA) was used for statistical analysis of the data sets and Duncan's multiple range test (DMRT) was used to compare the mean values.

Results

Physiological weight loss and spoilage percent

The loss of physiological weight of the strawberry fruit under refrigerated condition was very negligible during the entire storage period irrespective of MeJA concentration and its applications stages (Table 1). However, on 9^th day of storage, it was recorded maximum in control (3.12–3.19%) with minimum in two applications of 5–10 μM MeJA either at 45 + 75 DAP or 45 + 90 DAP (2.60–2.69%).

Table 1.

Effect of pre-harvest methyl jasmonate application on physiological weight loss (%) from ripe strawberry fruit (cv. ‘Winter Dawn’) under refrigerated storage condition.

Treatment		At 3^rd day after harvest	At 6^th day after harvest	At 9^th day after harvest
Stage of application (S)
45 Days after planting (DAP) (Vegetative stage)		1.80 ± 0.16^a	2.33 ± 0.16^a	2.94 ± 0.20^a
45 DAP + 60 DAP (Vegetative stage + Flowering stage)		1.82 ± 0.15^a	2.41 ± 0.15^a	2.96 ± 0.20^a
45 DAP + 75 DAP (Vegetative stage + Fruit Setting stage)		1.82 ± 0.16^a	2.32 ± 0.17^a	2.82 ± 0.28^b
45 DAP + 90 DAP (Vegetative stage + Fruit Maturity stage)		1.82 ± 0.19^a	2.42 ± 0.18^a	2.79 ± 0.27^b
Concentration of Methyl Jasmonate (C)
Control		1.89 ± 0.15^a	2.42 ± 0.15^a	3.15 ± 0.15^a
2.5 μM		1.82 ± 0.18^a	2.42 ± 0.17^a	2.87 ± 0.20^b
5.0 μM		1.78 ± 0.14^a	2.32 ± 0.18^a	2.76 ± 0.17^bc
10.0 μM		1.78 ± 0.15^a	2.32 ± 0.16^a	2.72 ± 0.19^c
S × C Interaction
45 DAP	Control	1.87 ± 0.11^a	2.37 ± 0.11^ab	3.13 ± 0.11^ab
	2.5 μM	1.79 ± 0.18^a	2.35 ± 0.18^ab	2.94 ± 0.18^abcde
	5.0 μM	1.80 ± 0.24^a	2.32 ± 0.24^ab	2.87 ± 0.24^bcdef
	10.0 μM	1.75 ± 0.17^a	2.28 ± 0.17^ab	2.81 ± 0.17^def
45 DAP + 60 DAP	Control	1.85 ± 0.19^a	2.44 ± 0.19^ab	3.16 ± 0.19^a
	2.5 μM	1.81 ± 0.26^a	2.42 ± 0.26^ab	2.98 ± 0.26^abcd
	5.0 μM	1.77 ± 0.13^a	2.34 ± 0.13^ab	2.82 ± 0.13^def
	10.0 μM	1.83 ± 0.05^a	2.43 ± 0.05^ab	2.86 ± 0.05^cdef
45 DAP + 75 DAP	Control	1.91 ± 0.14^a	2.45 ± 0.14^ab	3.19 ± 0.14^a
	2.5 μM	1.85 ± 0.12^a	2.36 ± 0.12^ab	2.81 ± 0.12^def
	5.0 μM	1.76 ± 0.16^a	2.24 ± 0.16^b	2.65 ± 0.16^f
	10.0 μM	1.77 ± 0.23^a	2.22 ± 0.23^b	2.61 ± 0.23^f
45 DAP + 90 DAP	Control	1.91 ± 0.24^a	2.43 ± 0.24^ab	3.12 ± 0.24^abc
	2.5 μM	1.83 ± 0.25^a	2.55 ± 0.12^a	2.74 ± 0.25^def
	5.0 μM	1.79 ± 0.11^a	2.36 ± 0.25^ab	2.69 ± 0.11^ef
	10.0 μM	1.75 ± 0.20^a	2.36 ± 0.11^ab	2.60 ± 0.20^f

Value indicates mean of three replicates ± standard error. Different letters in the same column indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

On the other hand, under refrigerated condition, not a single fruit was spoiled or decayed at 3^rd day of storage but it was started from 6^th day onwards, irrespective of treatment variation with significantly higher in control. Further, on 9^th day of storage, decay percent was recorded significantly higher as compared to 6^th day of storage (Table 2); although it was reduced significantly with the increasing MeJA concentration for pre-harvest applications up to 5.0 μM (17.71%) and started to increase with further increase of MeJA concentration (10.0 μM). It was also observed that strawberry fruit harvested from the plants treated with two pre-harvest sprays of 5.0 μM MeJA at 45 + 75 DAP had minimum decay per cent even on 9^th day of storage (10.00%) with non-significant variation in its two applications at same stages with 10.0 μM concentration and 5–10 μM concentration at 45 + 90 DAP; although 65–75% decay loss was recorded in control on 9^th day of storage.

Table 2.

Effect of pre-harvest methyl jasmonate application on decay loss (%) of ripe strawberry fruit (cv. ‘Winter Dawn’) under refrigerated storage condition.

Treatment		At 6^th day after harvest	At 9^th day after harvest
45 Days after planting (DAP) (Vegetative stage)		8.86 ± 1.67^a	46.46 ± 4.47^a
45 DAP + 60 DAP (Vegetative stage + Flowering stage)		8.35 ± 2.95^ab	35.00 ± 3.39^b
45 DAP + 75 DAP (Vegetative stage + Fruit Setting stage)		7.33 ± 3.52^bc	26.00 ± 3.78^c
45 DAP + 90 DAP (Vegetative stage + Fruit Maturity stage)		6.46 ± 3.21^c	24.54 ± 3.55^c
Concentration of Methyl Jasmonate (C)
Control		11.67 ± 2.49^a	70.42 ± 5.79^a
2.5 μM		7.06 ± 1.74^b	23.71 ± 2.68^b
5.0 μM		6.15 ± 1.55^b	17.71 ± 1.18^c
10.0 μM		6.13 ± 1.82^b	20.17 ± 2.90^c
S × C Interaction
45 DAP	Control	10.52 ± 1.81^abc	73.33 ± 5.77^a
	2.5 μM	8.75 ± 1.11^bcd	41.67 ± 4.64^c
	5.0 μM	8.34 ± 0.81^bcd	30.83 ± 3.82^d
	10.0 μM	7.83 ± 2.02^cde	40.00 ± 3.00^c
45 DAP + 60 DAP	Control	12.50 ± 2.50^a	75.00 ± 4.36^a
	2.5 μM	7.83 ± 1.26^cde	25.00 ± 3.00^de
	5.0 μM	6.25 ± 1.09^de	20.00 ± 2.00^ef
	10.0 μM	6.83 ± 1.61^de	20.00 ± 1.89^ef
45 DAP + 75 DAP	Control	12.67 ± 2.52^a	68.33 ± 3.51^ab
	2.5 μM	6.67 ± 1.04^de	15.67 ± 2.73^fg
	5.0 μM	5.00 ± 0.43^e	10.00 ± 1.19^g
	10.0 μM	5.00 ± 1.00^e	10.00 ± 2.00^g
45 DAP + 90 DAP	Control	11.00 ± 3.61^ab	65.00 ± 2.00^b
	2.5 μM	5.00 ± 1.00^e	12.50 ± 2.50^g
	5.0 μM	5.00 ± 0.50^e	10.00 ± 1.33^g
	10.0 μM	4.83 ± 1.04^e	10.67 ± 2.31^g

Value indicates mean of three replicates ± standard error. Different letters in the same column indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Total soluble solids (TSS) and total sugar content

The total soluble solids and total sugar content of the fruit were decreased gradually with increasing storage period, irrespective of treatment variation (Tables 3 and 4). However, under storage condition, maximum retention of TSS and total sugar over the storage period was estimated in two pre-harvest applications of 10.0 μM MeJA at 45 and 75 DAP which retained the TSS and total sugar at 6^th day of storage by 97.21 and 96.53%, respectively as compared to 3^rd day of storage and 90.07 and 91.57%, respectively on 9^th day of storage as compared to 6^th day. Similar retention rate of TSS and total sugar under refrigerated storage condition till 9^th day was also observed in the strawberry fruit harvested from the plants applied with two pre-harvest sprays of 5.0 μM MeJA at 45 + 75 DAP and 5–10 μM MeJA at 45 + 90 DAP with non-significant variation among them. However, the rate of retention in TSS and total sugar content in control on 9^th day of storage as compared to 6^th day was ranged from 68.14–70.18 and 60.08–72.92%, respectively.

Table 3.

Effect of pre-harvest methyl jasmonate application on TSS (^oB) of ripe strawberry fruit (cv. ‘Winter Dawn’) under refrigerated storage condition.

Treatment		On the day of harvest	At 3^rd day after harvest	At 6^th day after harvest	At 9^th day after harvest
Stage of application (S)
45 Days after planting (DAP) (Vegetative stage)		8.53 ± 0.14^b	8.58 ± 0.41^b	7.35 ± 0.92^b	4.97 ± 0.65^b
45 DAP + 60 DAP (Vegetative stage + Flowering stage)		8.88 ± 0.52^b	8.95 ± 0.55^b	7.46 ± 0.97^b	5.08 ± 0.74^b
45 DAP + 75 DAP (Vegetative stage + Fruit Setting stage)		10.10 ± 1.01^a	10.16 ± 1.20^a	9.29 ± 2.05^a	7.81 ± 2.26^a
45 DAP + 90 DAP (Vegetative stage + Fruit Maturity stage)		10.09 ± 1.21^a	10.14 ± 1.23^a	9.32 ± 2.09^a	7.81 ± 2.31^a
Concentration of Methyl Jasmonate (C)
Control		8.01 ± 0.11^b	8.15 ± 0.12^b	6.13 ± 0.42^c	4.25 ± 0.43^b
2.5 μM		9.70 ± 0.96^a	9.75 ± 1.03^a	8.76 ± 1.46^b	6.89 ± 1.86^a
5.0 μM		10.17 ± 0.91^a	10.21 ± 0.94^a	9.46 ± 1.49^a	7.25 ± 2.10^a
10.0 μM		9.70 ± 0.89^a	9.72 ± 0.99^a	9.06 ± 1.54^ab	7.28 ± 2.22^a
S × C Interaction
45 DAP	Control	7.95 ± 0.11^h	8.11 ± 0.12ⁱ	6.13 ± 0.31^c	4.28 ± 0.31^bcd
	2.5 μM	8.57 ± 0.18^fg	8.59 ± 0.15^g	7.46 ± 0.55^b	5.11 ± 0.55^bcd
	5.0 μM	9.11 ± 0.45^de	9.16 ± 0.16^f	8.11 ± 0.76^b	5.26 ± 0.76^bcd
	10.0 μM	8.46 ± 0.31^gh	8.47 ± 0.15^gh	7.68 ± 0.65^b	5.21 ± 0.65^bcd
45 DAP + 60 DAP	Control	8.03 ± 0.25^h	8.13 ± 0.15ⁱ	6.12 ± 0.43^c	4.17 ± 0.43^d
	2.5 μM	8.95 ± 0.14^ef	8.99 ± 0.18^f	7.63 ± 0.90^b	5.39 ± 0.90^bc
	5.0 μM	9.47 ± 0.33^d	9.51 ± 0.15^e	8.21 ± 0.43^b	5.41 ± 0.43^b
	10.0 μM	9.13 ± 0.24^de	9.15 ± 0.21^f	7.86 ± 0.43^b	5.34 ± 0.43^bcd
45 DAP + 75 DAP	Control	8.06 ± 0.07^gh	8.21 ± 0.08^hi	6.17 ± 0.37^c	4.33 ± 0.37^bcd
	2.5 μM	10.56 ± 0.21^bc	10.62 ± 0.32^cd	9.76 ± 0.63^a	8.37 ± 0.63^a
	5.0 μM	11.02 ± 0.45^ab	11.05 ± 0.05^ab	10.74 ± 1.05^a	9.11 ± 1.05^a
	10.0 μM	10.74 ± 0.48^abc	10.77 ± 0.22^bc	10.47 ± 1.18^a	9.43 ± 1.18^a
45 DAP + 90 DAP	Control	8.03 ± 0.22^h	8.16 ± 0.15ⁱ	6.11 ± 0.75^c	4.21 ± 0.75^cd
	2.5 μM	10.75 ± 0.46^abc	10.79 ± 0.22^bc	10.19 ± 1.10^a	8.68 ± 1.10^a
	5.0 μM	11.11 ± 0.28^a	11.12 ± 0.27^a	10.76 ± 0.55^a	9.23 ± 0.55^a
	10.0 μM	10.45 ± 0.09^c	10.47 ± 0.01^d	10.22 ± 0.99^a	9.12 ± 0.99^a

Value indicates mean of three replicates ± standard error. Different letters in the same column indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Table 4.

Effect of pre-harvest methyl jasmonate application on total sugar content (%) of ripe strawberry fruit (cv. ‘Winter Dawn’) under refrigerated storage condition.

Treatment		On the day of harvest	At 3^rd day after harvest	At 6^th day after harvest	At 9^th day after harvest
Stage of application (S)
45 Days after planting (DAP) (Vegetative stage)		6.04 ± 0.24^b	6.06 ± 0.27^b	5.14 ± 0.60^b	3.56 ± 0.40^b
45 DAP + 60 DAP (Vegetative stage + Flowering stage)		6.27 ± 0.37^b	6.29 ± 0.41^b	5.19 ± 0.66^b	3.63 ± 0.45^b
45 DAP + 75 DAP (Vegetative stage + Fruit Setting stage)		7.10 ± 0.48^a	7.11 ± 0.83^a	6.45 ± 0.41^a	5.53 ± 0.59^a
45 DAP + 90 DAP (Vegetative stage + Fruit Maturity stage)		7.27 ± 0.56^a	7.29 ± 0.45^a	6.62 ± 0.12^a	5.54 ± 0.62^a
Concentration of Methyl Jasmonate (C)
Control		5.88 ± 0.41^c	6.00 ± 0.49^c	4.47 ± 0.41^c	3.08 ± 0.25^b
2.5 μM		6.84 ± 0.53^ab	6.83 ± 0.71^ab	6.11 ± 0.98^b	4.88 ± 0.31^a
5.0 μM		7.18 ± 0.46^a	7.14 ± 0.65^a	6.58 ± 0.65^a	5.14 ± 0.46^a
10.0 μM		6.77 ± 0.56^b	6.77 ± 0.63^b	6.26 ± 0.42^ab	5.15 ± 0.55^a
S × C Interaction
45 DAP	Control	5.66 ± 0.18^ef	5.77 ± 0.17^e	4.32 ± 0.18^d	3.15 ± 0.18^bcde
	2.5 μM	6.05 ± 0.09^de	6.04 ± 0.14^de	5.23 ± 0.36^bc	3.62 ± 0.36^bcde
	5.0 μM	6.42 ± 0.11^cd	6.39 ± 0.21^cd	5.61 ± 0.49^bc	3.74 ± 0.49^bcde
	10.0 μM	6.03 ± 0.33^def	6.03 ± 0.16^de	5.42 ± 0.35^bc	3.71 ± 0.35^bcde
45 DAP + 60 DAP	Control	5.62 ± 0.08^f	5.72 ± 0.32^e	4.26 ± 0.31^d	3.08 ± 0.31^cde
	2.5 μM	6.33 ± 0.14^cd	6.31 ± 0.19^d	5.34 ± 0.55^bc	3.82 ± 0.55^bc
	5.0 μM	6.75 ± 0.08^c	6.71 ± 0.11^c	5.76 ± 0.29^b	3.84 ± 0.29^b
	10.0 μM	6.36 ± 0.20^cd	6.39 ± 0.11^cd	5.41 ± 0.11^bc	3.77 ± 0.11^bcd
45 DAP + 75 DAP	Control	5.65 ± 0.21^ef	5.78 ± 0.21^e	4.29 ± 0.22^d	3.06 ± 0.22^de
	2.5 μM	7.43 ± 0.11^ab	7.43 ± 0.22^ab	6.82 ± 0.39^a	5.92 ± 0.39^a
	5.0 μM	7.77 ± 0.30^a	7.72 ± 0.18^a	7.46 ± 0.60^a	6.49 ± 0.60^a
	10.0 μM	7.53 ± 0.22^ab	7.50 ± 0.22^ab	7.24 ± 0.86^a	6.63 ± 0.86^a
45 DAP + 90 DAP	Control	6.59 ± 0.32^c	6.73 ± 0.26^c	5.01 ± 0.39^c	3.01 ± 0.39^e
	2.5 μM	7.55 ± 0.23^ab	7.53 ± 0.32^ab	7.02 ± 0.84^a	6.17 ± 0.84^a
	5.0 μM	7.77 ± 0.20^a	7.75 ± 0.24^a	7.48 ± 0.39^a	6.49 ± 0.39^a
	10.0 μM	7.16 ± 0.06^b	7.17 ± 0.04^b	6.96 ± 0.72^a	6.47 ± 0.72^a

Value indicates mean of three replicates ± standard error. Different letters in the same column indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Titratable acidity (%)

With the increasing storage period, titratable acidity (%) decreased gradually in all the treatments (Table 5). However, on 9^th day of storage, maximum titratable acidity in the stored fruit was recorded in two sprays of 2.5 μM MeJA at 45 + 90 DAP which was statistically at par with its applications at 5–10 μM concentration during 45 + 75 DAP or 45 + 90 DAP (88.89–95.00% retention as compared to 6^th day of storage); however, least retention of titratable acidity on 9^th day was recorded in control (74.65 68.06–82.61% retention as compared to 6^th day of storage).

Table 5.

Effect of pre-harvest methyl jasmonate application on titratable acidity (%) of ripe strawberry fruit (cv. ‘Winter Dawn’) under refrigerated storage condition.

Treatment		On the day of harvest	At 3^rd day after harvest	At 6^th day after harvest	At 9^th day after harvest
Stage of application (S)
45 Days after planting (DAP) (Vegetative stage)		0.95 ± 0.03^a	0.84 ± 0.06^a	0.72 ± 0.02^a	0.54 ± 0.07^b
45 DAP + 60 DAP (Vegetative stage + Flowering stage)		0.79 ± 0.10^bc	0.72 ± 0.09^c	0.62 ± 0.05^c	0.55 ± 0.05^ab
45 DAP + 75 DAP (Vegetative stage + Fruit Setting stage)		0.76 ± 0.08^c	0.70 ± 0.11^c	0.65 ± 0.05^bc	0.56 ± 0.07^ab
45 DAP + 90 DAP (Vegetative stage + Fruit Maturity stage)		0.81 ± 0.12^b	0.77 ± 0.11^b	0.69 ± 0.03^ab	0.60 ± 0.08^a
Concentration of Methyl Jasmonate (C)
Control		1.00 ± 0.03^a	0.87 ± 0.06^a	0.70 ± 0.03^a	0.53 ± 0.06^b
2.5 μM		0.80 ± 0.09^b	0.75 ± 0.09^b	0.67 ± 0.06^ab	0.57 ± 0.08^ab
5.0 μM		0.75 ± 0.08^c	0.70 ± 0.09^c	0.64 ± 0.07^b	0.57 ± 0.06^ab
10.0 μM		0.75 ± 0.06^bc	0.72 ± 0.09^bc	0.66 ± 0.05^ab	0.58 ± 0.07^a
S × C Interaction
45 DAP	Control	1.01 ± 0.03^a	0.86 ± 0.04^ab	0.71 ± 0.01^ab	0.53 ± 0.04^bcd
	2.5 μM	0.96 ± 0.05^abc	0.84 ± 0.06^ab	0.73 ± 0.02^a	0.51 ± 0.10^cd
	5.0 μM	0.91 ± 0.07^b^c	0.82 ± 0.08^ab	0.73 ± 0.03^a	0.55 ± 0.08^abcd
	10.0 μM	0.91 ± 0.07^bc	0.82 ± 0.07^ab	0.72 ± 0.03^a	0.55 ± 0.07^abcd
45 DAP + 60 DAP	Control	0.99 ± 0.04^abc	0.84 ± 0.05^ab	0.69 ± 0.03^abc	0.57 ± 0.05^abcd
	2.5 μM	0.76 ± 0.05^de	0.71 ± 0.08^cd	0.61 ± 0.04^bcd	0.56 ± 0.09^abcd
	5.0 μM	0.70 ± 0.02^de	0.66 ± 0.04^de	0.58 ± 0.04^d	0.53 ± 0.04^bcd
	10.0 μM	0.71 ± 0.02^de	0.67 ± 0.03^de	0.61 ± 0.03^bcd	0.55 ± 0.03^abcd
45 DAP + 75 DAP	Control	1.00 ± 0.06^ab	0.87 ± 0.05^ab	0.72 ± 0.01^a	0.49 ± 0.05^d
	2.5 μM	0.69 ± 0.02^e	0.66 ± 0.04^de	0.63 ± 0.03^abcd	0.58 ± 0.04^abcd
	5.0 μM	0.66 ± 0.05^e	0.61 ± 0.07^e	0.60 ± 0.01^cd	0.57 ± 0.07^abcd
	10.0 μM	0.67 ± 0.05^e	0.67 ± 0.08^de	0.64 ± 0.03^abcd	0.59 ± 0.08^abcd
45 DAP + 90 DAP	Control	1.01 ± 0.09^a	0.91 ± 0.10^a	0.68 ± 0.04^abc	0.51 ± 0.09^cd
	2.5 μM	0.80 ± 0.07^d	0.78 ± 0.08^bc	0.72 ± 0.02^a	0.64 ± 0.08^a
	5.0 μM	0.72 ± 0.04^de	0.69 ± 0.03^cde	0.66 ± 0.01^abcd	0.61 ± 0.03^abc
	10.0 μM	0.72 ± 0.04^de	0.72 ± 0.07^cd	0.68 ± 0.03^abcd	0.63 ± 0.07^ab

Value indicates mean of three replicates ± standard error. Different letters in the samecolumn indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Ascorbic acid and anthocyanin content

With the increasing storage period, ascorbic acid and anthocyanin content of the stored strawberry fruit decreased gradually in all the treatments (Tables 6 and 7). However, on 9^th day of storage, maximum ascorbic acid and anthocyanin content in the stored fruit was recorded in two sprays of 5.0 μM MeJA at 45 + 90 DAP (57.11 mg 100 g⁻¹ FW) and 10 μM MeJA at 45 + 75 DAP (28.77 mg 100 g⁻¹ FW), respectively which was statistically at par with its two applications at 5–10 μM concentration during 45 + 75 DAP and 45 + 90 DAP. However, least retention of ascorbic acid and anthocyanin content on 9^th day was recorded in control (64.13–78.54 and 63.67–70.69% retention, respectively as compared to 6^th day of storage).

Table 6.

Effect of pre-harvest methyl jasmonate application on ascorbic acid content (mg 100 g⁻¹) of ripe strawberry fruit (cv. ‘Winter Dawn’) under refrigerated storage condition.

Treatment		On the day of harvest	At 3^rd day after harvest	At 6^th day after harvest	At 9^th day after harvest
Stage of application (S)
45 Days after planting (DAP) (Vegetative stage)		54.75 ± 4.78^c	50.50 ± 3.23^c	30.99 ± 2.28^c	20.70 ± 2.49^b
45 DAP + 60 DAP (Vegetative stage + Flowering stage)		58.77 ± 4.98^b	56.11 ± 3.42^b	36.00 ± 3.34^b	21.77 ± 2.15^b
45 DAP + 75 DAP (Vegetative stage + Fruit Setting stage)		67.91 ± 5.24^a	65.18 ± 3.11^a	54.76 ± 4.66^a	45.21 ± 2.38^a
45 DAP + 90 DAP (Vegetative stage + Fruit Maturity stage)		68.51 ± 4.97^a	65.73 ± 2.83^a	56.11 ± 3.02^a	46.58 ± 2.73^a
Concentration of Methyl Jasmonate (C)
Control		51.76 ± 3.11^c	45.94 ± 3.20^c	25.06 ± 2.98^c	17.65 ± 2.85^b
2.5 μM		64.08 ± 4.33^b	61.59 ± 5.01^b	48.72 ± 4.06^b	37.91 ± 3.90^a
5.0 μM		68.22 ± 4.77^a	66.32 ± 6.40^a	52.63 ± 4.31^a	39.28 ± 3.60^a
10.0 μM		65.87 ± 4.81^ab	63.67 ± 7.53^ab	51.45 ± 4.85^ab	39.39 ± 3.39^a
S × C Interaction
45 DAP	Control	51.42 ± 2.05^c	43.21 ± 2.10^e	24.14 ± 2.10^g	18.96 ± 2.10^bc
	2.5 μM	56.38 ± 3.36^bc	52.59 ± 3.43^cd	33.20 ± 3.43^de	23.15 ± 3.43^bc
	5.0 μM	60.09 ± 4.64^b	57.41 ± 4.68^bc	34.96 ± 4.69^cd	19.59 ± 4.69^bc
	10.0 μM	51.11 ± 3.66^c	48.77 ± 3.62^de	31.67 ± 3.62^def	21.11 ± 3.62^bc
45 DAP + 60 DAP	Control	52.08 ± 2.62^c	47.48 ± 2.59^de	23.69 ± 2.59^g	17.45 ± 2.59^bc
	2.5 μM	57.73 ± 5.35^bc	55.63 ± 5.42^bc	36.74 ± 5.41^bcd	21.59 ± 5.41^bc
	5.0 μM	63.12 ± 2.75^b	61.25 ± 2.74^b	42.59 ± 2.74^b	24.33 ± 2.74^b
	10.0 μM	62.13 ± 2.80^b	60.08 ± 2.82^b	41.01 ± 2.82^bc	23.69 ± 2.82^bc
45 DAP + 75 DAP	Control	51.71 ± 2.21^c	46.85 ± 2.24^de	26.58 ± 2.24^efg	17.64 ± 2.24^bc
	2.5 μM	70.54 ± 4.01^a	68.78 ± 4.06^a	62.47 ± 4.06^a	51.23 ± 4.06^a
	5.0 μM	74.55 ± 6.42^a	72.96 ± 5.46^a	64.86 ± 4.46^a	56.11 ± 4.46^a
	10.0 μM	74.82 ± 7.51^a	72.14 ± 4.54^a	65.11 ± 5.54^a	55.84 ± 4.54^a
45 DAP + 90 DAP	Control	51.84 ± 4.91^c	46.23 ± 4.92^de	25.84 ± 4.93^fg	16.57 ± 4.93^c
	2.5 μM	71.68 ± 6.78^a	69.36 ± 4.80^a	62.48 ± 4.80^a	55.69 ± 4.80^a
	5.0 μM	75.11 ± 3.55^a	73.65 ± 3.60^a	68.12 ± 3.60^a	57.11 ± 3.60^a
	10.0 μM	75.42 ± 6.51^a	73.67 ± 4.56^a	68.00 ± 4.56^a	56.94 ± 4.56^a

Value indicates mean of three replicates ± standard error. Different letters in the same column indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Table 7.

Effect of pre-harvest methyl jasmonate application on anthocyanin content (mg 100 g⁻¹ FW) of ripe strawberry fruit (cv. ‘Winter Dawn’) under refrigerated storage condition.

Treatment		On the day of harvest	At 3^rd day after harvest	At 6^th day after harvest	At 9^th day after harvest
Stage of application (S)
45 Days after planting (DAP) (Vegetative stage)		28.86 ± 2.05^c	26.20 ± 3.45^c	21.44 ± 3.38^c	15.14 ± 1.86^b
45 DAP + 60 DAP (Vegetative stage + Flowering stage)		31.45 ± 4.21^b	28.56 ± 2.62^b	24.64 ± 2.72^b	15.15 ± 1.39^b
45 DAP + 75 DAP (Vegetative stage + Fruit Setting stage)		33.90 ± 3.09^a	30.93 ± 2.58^a	26.94 ± 2.13^a	22.30 ± 1.54^a
45 DAP + 90 DAP (Vegetative stage + Fruit Maturity stage)		34.12 ± 3.15^a	31.17 ± 2.12^a	27.06 ± 2.95^a	21.96 ± 1.46^a
Concentration of Methyl Jasmonate (C)
Control		26.26 ± 1.21^c	20.95 ± 1.42^c	13.29 ± 1.54^c	9.03 ± 1.36^c
2.5 μM		31.41 ± 2.44^b	29.00 ± 2.96^b	26.24 ± 1.26^b	19.82 ± 1.41^b
5.0 μM		35.35 ± 3.19^a	33.82 ± 1.84^a	30.54 ± 2.19^a	22.84 ± 2.18^a
10.0 μM		35.31 ± 3.04^a	33.09 ± 1.95^a	30.02 ± 1.80^a	22.85 ± 1.28^a
S × C Interaction
45 DAP	Control	26.46 ± 1.10^g	21.32 ± 1.11^h	13.10 ± 1.11^h	9.26 ± 1.11^d
	2.5 μM	28.78 ± 1.63^efg	26.28 ± 1.63^g	22.45 ± 1.63^g	16.84 ± 1.63^c
	5.0 μM	30.14 ± 2.17^def	28.66 ± 2.18^efg	24.86 ± 2.18^fg	16.96 ± 2.18^c
	10.0 μM	30.05 ± 2.00^def	28.55 ± 2.00^efg	25.36 ± 2.00^fg	17.48 ± 2.00^c
45 DAP + 60 DAP	Control	25.47 ± 1.31^g	20.42 ± 1.32^h	12.47 ± 1.32^h	8.45 ± 1.32^d
	2.5 μM	30.60 ± 3.06^cde	28.01 ± 3.06^fg	26.08 ± 3.06^ef	17.63 ± 3.06^c
	5.0 μM	35.04 ± 1.45^ab	33.62 ± 1.45^abc	30.06 ± 1.45^bcd	17.44 ± 1.45^c
	10.0 μM	34.69 ± 1.67^b	32.18 ± 1.67^bcd	29.96 ± 1.67^bcd	17.08 ± 1.67^c
45 DAP + 75 DAP	Control	26.98 ± 1.18^gf	21.59 ± 1.19^h	14.56 ± 1.19^h	9.27 ± 1.19^d
	2.5 μM	32.55 ± 1.74^bcd	30.11 ± 1.74^def	27.48 ± 1.74^def	22.69 ± 1.74^b
	5.0 μM	38.07 ± 3.12^a	36.87 ± 3.12^a	33.54 ± 3.12^a	28.47 ± 3.12^a
	10.0 μM	37.99 ± 3.45^a	35.17 ± 3.46^ab	32.19 ± 3.46^abc	28.77 ± 3.46^a
45 DAP + 90 DAP	Control	26.14 ± 2.27^g	20.47 ± 2.27^h	13.01 ± 2.27^h	9.15 ± 2.27^d
	2.5 μM	33.69 ± 2.87^bc	31.63 ± 2.87^cde	28.97 ± 2.87^cde	22.13 ± 2.87^b
	5.0 μM	38.16 ± 1.73^a	36.11 ± 1.73^a	33.69 ± 1.73^a	28.47 ± 1.73^a
	10.0 μM	38.48 ± 3.35^a	36.49 ± 3.35^a	32.58 ± 3.35^ab	28.08 ± 3.35^a

Value indicates mean of three replicates ± standard error. Different letters in the same column indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Antioxidant capacity

Antioxidant capacity of the fruit was decreases gradually with the increasing storage period, irrespective of treatment variation (Table 8). However, under storage condition, maximum retention of antioxidant capacity over the storage period was estimated in two pre-harvest applications of 5.0 μM MeJA at 45 and 75 DAP which retained the antioxidant capacity at 6^th day of storage by 91.44% as compared to 3^rd day of storage and 93.10% on 9^th day of storage as compared to 6^th day. Similar retention rate of antioxidant capacity under refrigerated storage condition till 9^th day was also observed in the strawberry fruit harvested from the plants applied with two pre-harvest sprays of 10.0 μM MeJA at 45 + 75 DAP and 5–10 μM MeJA at 45 + 90 DAP with non-significant variation among them. However, the rate of retention in antioxidant capacity in control on 9^th day of storage as compared to 6^th day was ranged from 80.17–86.44%.

Table 8.

Effect of pre-harvest methyl jasmonate application on antioxidant capacity (µ mol TE 100 g⁻¹ FW) of strawberry fruit (cv. ‘Winter Dawn’) under refrigerated storage condition.

Treatment		On the day of harvest	At 3^rd day after harvest	At 6^th day after harvest	At 9^th day after harvest
Stage of application (S)
45 Days after planting (DAP) (Vegetative stage)		1.82 ± 0.10^b	1.70 ± 0.15^b	1.39 ± 0.17^c	1.20 ± 0.15^b
45 DAP + 60 DAP (Vegetative stage + Flowering stage)		1.92 ± 0.11^b	1.78 ± 0.17^b	1.53 ± 0.23^b	1.28 ± 0.18^b
45 DAP + 75 DAP (Vegetative stage + Fruit Setting stage)		2.10 ± 0.21^a	1.96 ± 0.22^a	1.72 ± 0.19^a	1.57 ± 0.12^a
45 DAP + 90 DAP (Vegetative stage + Fruit Maturity stage)		2.12 ± 0.21^a	1.99 ± 0.20^a	1.76 ± 0.20^a	1.58 ± 0.13^a
Concentration of Methyl Jasmonate (C)
Control		1.75 ± 0.15^c	1.52 ± 0.06^c	1.18 ± 0.09^c	0.99 ± 0.11^c
2.5 μM		1.98 ± 0.15^b	1.87 ± 0.15^b	1.65 ± 0.20^b	1.46 ± 0.22^b
5.0 μM		2.12 ± 0.21^a	2.03 ± 0.23^a	1.80 ± 0.18^a	1.59 ± 0.13^a
10.0 μM		2.11 ± 0.15^a	2.01 ± 0.23^a	1.78 ± 0.19^a	1.59 ± 0.14^a
S × C Interaction
45 DAP	Control	1.73 ± 0.07^de	1.53 ± 0.07^f	1.18 ± 0.07^e	1.02 ± 0.07^fg
	2.5 μM	1.80 ± 0.12^cde	1.72 ± 0.12^e	1.46 ± 0.12^cd	1.28 ± 0.12^de
	5.0 μM	1.89 ± 0.16^cde	1.78 ± 0.16^cde	1.48 ± 0.16^cd	1.22 ± 0.16^def
	10.0 μM	1.87 ± 0.14^cde	1.75 ± 0.14^de	1.44 ± 0.14^d	1.27 ± 0.14^de
45 DAP + 60 DAP	Control	1.78 ± 0.09^de	1.53 ± 0.09^f	1.19 ± 0.09^e	1.05 ± 0.09^efg
	2.5 μM	1.95 ± 0.20^bcde	1.84 ± 0.10^cde	1.62 ± 0.20^bcd	1.33 ± 0.20^d
	5.0 μM	1.97 ± 0.09^bcd	1.89 ± 0.09^bcd	1.65 ± 0.09^bcd	1.38 ± 0.09^cd
	10.0 μM	1.98 ± 0.09^bcde	1.87 ± 0.10^bcd	1.66 ± 0.10^bcd	1.35 ± 0.10^cd
45 DAP + 75 DAP	Control	1.74 ± 0.08^e	1.51 ± 0.08^f	1.18 ± 0.08^e	0.96 ± 0.08^g
	2.5 μM	2.05 ± 0.12^bc	1.91 ± 0.12^bc	1.70 ± 0.12^bc	1.57 ± 0.12^bc
	5.0 μM	2.33 ± 0.22^a	2.22 ± 0.12^a	2.03 ± 0.22^a	1.89 ± 0.12^a
	10.0 μM	2.32 ± 0.25^a	2.20 ± 0.16^a	1.99 ± 0.15^a	1.86 ± 0.15^a
45 DAP + 90 DAP	Control	1.75 ± 0.16^de	1.53 ± 0.04^f	1.16 ± 0.17^e	0.93 ± 0.17^g
	2.5 μM	2.11 ± 0.22^ab	2.00 ± 0.12^b	1.84 ± 0.22^ab	1.65 ± 0.12^ab
	5.0 μM	2.30 ± 0.11^a	2.22 ± 0.05^a	2.03 ± 0.11^a	1.86 ± 0.11^a
	10.0 μM	2.31 ± 0.22^a	2.20 ± 0.12^a	2.01 ± 0.22^a	1.88 ± 0.12^a

Value indicates mean of three replicates ± standard error. Different letters in the same column indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Polyphenol oxidase (PPO) and peroxidise (POD) activity

With the increasing storage period, PPO activity increased gradually in all the treatments (Figure 2). However, on 9^th day of storage, least PPO activity in the stored fruit was recorded in two sprays of 10 μM MeJA at 45 + 90 DAP (2.90 unit mg⁻¹ protein) which was statistically at par with its two applications at same time with 5 μM concentration and 5–10 μM concentration at 45 + 75 DAP; however, the highest PPO activity in the stored fruit on 9^th day was recorded in control (5.49–5.67 unit mg⁻¹ protein). Similarly, with the increasing storage period, POD activity also increased gradually in all the treatments (Figure 3) and on 9^th day of storage, the highest POD activity in the stored fruit on 9^th day was recorded in control (4.58–4.68 unit mg⁻¹ protein) with least value in two sprays of 10 μM MeJA at 45 + 90 DAP (2.33 unit mg⁻¹ protein).

Figure 2.

Effect of pre-harvest methyl jasmonate application on polyphenol oxidase activity in the ripe strawberry fruit cv. ‘Winter Dawn’ under refrigerated condition. Vertical bar indicates mean value of three replication ± standard error. Different letters on vertical bars indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Figure 3.

Effect of pre-harvest methyl jasmonate application on peroxidase oxidase activity in the ripe strawberry fruit cv. ‘Winter Dawn’ under refrigerated condition. Vertical bar indicates mean value of three replication ± standard error. Different letters on vertical bars indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Catalase and phenylalanine amino-lyase activity (PAL)

In contrary to PPO and POD activity, catalase and PAL activity in the stored strawberry fruit of cultivar ‘Winter Dawn’ was decreased gradually with the increasing storage period irrespective of treatment variation (Figures 4 and 5). However, under storage condition, maximum retention of catalase activity over the storage period was estimated in two pre-harvest applications of 10.0 μM MeJA at 45 and 90 DAP which retained the catalase activity at 6^th day of storage by 89.77% as compared to 3^rd day of storage and 84.10% on 9^th day of storage as compared to 6^th day. Similar retention of catalase activity under refrigerated storage condition till 9^th day was also observed in the strawberry fruit harvested from the plants applied with two pre-harvest sprays of 5.0 μM MeJA at 45 + 90 DAP and 5–10 μM MeJA at 45 + 75 DAP with non-significant variation among them. However, the rate of retention in catalase activity in control on 9^th day of storage as compared to 6^th day was ranged from 61.43–71.32%. Similarly, retention of PAL activity under refrigerated storage condition till 9^th day was observed in the strawberry fruit harvested from the plants applied with two pre-harvest sprays of 5.0 μM MeJA at 45 + 90 DAP and 5–10 μM MeJA at 45 + 75 DAP with non-significant variation among them. However, the rate of retention in PAL activity in control on 9^th day of storage as compared to 6^th day was ranged from 58.21–67.19%.

Figure 4.

Effect of pre-harvest methyl jasmonate application on catalase activity in the ripe strawberry fruit cv. ‘Winter Dawn’ under refrigerated condition. Vertical bar indicates mean value of three replication ± standard error. Different letters on vertical bars indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Figure 5.

Effect of pre-harvest methyl jasmonate application on phenylalanine ammino-lyase activity in the ripe strawberry fruit cv. ‘Winter Dawn’ under refrigerated condition. Vertical bar indicates mean value of three replication ± standard error. Different letters on vertical bars indicate significant differences at P ≤ 0.05 (Duncan's Multiple Range Test).

Discussion

Physiological weight loss and spoilage percent

The physiological weight loss in strawberry fruit is primarily caused by the evaporative water loss from the fruit surface. Further, it was also accelerated by the faster metabolic activities such as cellular breakdown due to respiration and damage at low temperature. These factors contribute significantly to postharvest weight loss. The applications of MeJA helps to mitigate this loss, as evidenced by the reduction in respiratory rate during the storage period^32–34 which ultimately helps to reduce the weight loss significantly under the current investigation. Further, methyl jasmonate-treated fruit have been shown to induce the synthesis and expression of stress induced proteins such as heat-shock proteins and pathogenesis-related proteins, which lead to increase the resistance against pathogens and the decreased the incidence of decay loss.^35,36 In strawberry fruit, the suppression of fungal decay might be induced by chemical-defence mechanisms of plant tissues by low concentration of jasmonate.³⁷

Fruit quality attributes

The total soluble solids, titratable acidity and total sugar content of the stored strawberry fruit decreased gradually with the increasing storage period with maximum in control. It might be due to the significant water loss and decay loss from the fruit in control on 6^th and 9^th day of storage. The microbial population present on the fruit surface leads to the degradation of all the solid part of the fruit, resulting sharp decline in TSS and total sugar content. However, negligible microbial infection or decay loss was observed under pre-harvest methyl jasmonate applications. Hence, the TSS and sugar content of the fruit were retained significantly even on 9^th day of storage under MeJa treatment. Similar findings were also reported in grapes,³⁸ Chinese chives³⁹ etc.

The ascorbic acid concentration in the stored strawberry fruit commonly decreases after harvest. It might be due to the oxidation reaction of ascorbic acid during senescence process after harvesting. In addition, it also reported that ascorbic acid oxidase play significant role for rapid transformation of L-ascorbic acid into dehydro-ascorbic acid, which results in the reduction of ascorbic acid content of the fruit during storage.⁴⁰ However, this trend of reduction of ascorbic acid was slowed down in pre-harvest MeJA treatment followed by refrigerated storage of the fruit. This is mainly due to the slow rate ascorbic acid degradation by MeJA treatment as it helped to delay the activity of ascorbate oxidase.⁴¹ Further, it is also evident that the presence of MeJA within the fruit tissues helps to prevents the ROS accumulation by increasing the enzymatic activity in the fruit cells and helps to increase the accumulation of antioxidant compounds such as ascorbic acid, glutathione and flavonids.^42,43 In addition, these antioxidant compounds play vital role as scavenging agent against superoxide, hydroxyl, and DPPH radicals during the storage³⁹ which ultimately helps to reduce the rate of oxidative reactions within the fruit under storage condition and indirectly leads to prevent the degradation of different biochemical components of the fruit, subjected to pre-harvest applications of MeJA at 75 or 90 DAP with the concentration ranging from 5–10 μM. Hence, the fruit under these treatment combinations have the maximum shelf life of about 9 days under refrigerated conditions; although the fruit of control treatment started to deteriorate from 6^th day of storage.

Enzymatic activity in the harvested fruit

Polyphenol oxidase (PPO) and peroxidise (POD) are the oxidative enzymes which accelerate the oxidation process of phenolic compounds present in the fruit leads to the formation of reduced oxygen species such as superoxide radicles (O₂⁻) and free radicals which are highly toxic for the fruit and cause faster deterioration of the fruit after harvesting. Pre-harvest applications of MeJA at fruit developmental phases (75 or 90 DAP) helped to reduce the activity of both PPO and POD significantly over control resulting significant reduction of oxidative reactions in the treated strawberry fruit. Further, the applications of MeJA play vital role for increasing the level of hydrogen peroxide in the strawberry fruit⁴⁴ which might help to increase the activity of catalase and thus inducing tolerance against oxidative stress.⁴⁵ The increasing level of total phenolic compounds including anthocyanin in the ripe strawberry fruit, harvested from the plants treated with MeJA at 5–10 μM during fruit developmental phases is directly correlated with the increased activity of Phenylalanine amino-lyase within the fruit^46,47 resulting negligible spoilage of the fruit even on the 9^th day of storage under refrigerated condition.

Conclusion

From the research findings of the present investigation, it can be concluded that pre-harvest applications of 5.0 μM methyl jasmonate at 45 and again at 75 days after planting (DAP) followed by refrigerated storage of ripe strawberry fruit at 8°C temperature with 55–60% relative humidity is effective to improve the shelf life of strawberry cv. ‘Winter Dawn’ up to 9 days without any deterioration in fruit quality attributes. Hence, pre-harvest applications of 5.0 μM methyl jasmonate at 45 and again at 75 DAP followed by refrigerated storage of ripe strawberry fruit can be recommended for improving the shelf life of strawberry cv. ‘Winter Dawn’ up to 9 days under semi-arid ecosystem of Bundhelkhand, India.

Footnotes

Acknowledgements

Authors are heartily thankful to Hon’ble Vice Chancellor, Rani Lakshmi Bai Central Agricultural University (RLBCAU), Jhansi, India, for providing all the necessary facilities. Director Education, RLBCAU, Jhansi, India and Dean, College of Horticulture & Forestry, RLBCAU, Jhansi, India is also acknowledged for their continuous support and valuable suggestions.

ORCID iDs

Manoj Kundu

Ranjit Pal

Ethical approval and informed consent statements

This study did not involve human participants or animals and was based on plant analysis; therefore, ethical approval and informed consent were not required.

Authors’ contributions

Conceptualization of the research work - M.K., R.P., and G.S.A.; Methodology - D.P., and T.T; Validation of work - M.K., R.P., and S.M.; Data analysis - S.M., and M.K.; Investigation - D.P., and T.T.; Resources availability - M.K., R.P., and S.M.; Data curation - S.M., and M.K.; Writing, original draft preparation - D.P., and M.K.; Review and editing of manuscript - G.S.A., and S.M.; Visualization - R.P., and S.M.; Supervision- M.K.

All authors have read and agreed to the published version of the manuscript.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The fund for this research work was sourced by Rani Lakshmi Bai Central Agricultural University, Jhansi, India.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

References

Giampieri

Tulipani

Alvarez-Suarez

, et al. The strawberry: composition, nutritional quality, and impact on human health. Nutrition 2012; 28: 9–19.

Hadi

Askarpour

Miraghajani

, et al. Effects of strawberry supplementation on cardiovascular risk factors: a comprehensive systematic review and meta-analysis of randomized controlled trials. Food Funct 2019; 10: 6987–6998.

Zhao

Yin

. Improvement of quality and shelf-life in strawberries by Pichia guilliermondii and hot air treatment. New Zeal J Crop Hort Sci 2023; 53: 163–179.

Khatoon

Kundu

Mir

, et al. Exogenous Brassinolide applications improves growth, yield and quality of strawberry grown in the subtropics. Erwerbs-Obstbau 2023; 65: 2271–2279.

Kundu

Rai

Bist

. Effect of Plant bio-regulators (PBRs) on growth, flowering, fruiting and quality in low chill pear [Pyruspyrifolia (Brum.) Nakai] cv Gola. Pantnagar J Res 2013; 11: 234–238.

Prasad

Sahay

Patel

, et al. Effect of foliar applications of PGR and different potassium forms on sex expression, fruit setting, yield and fruit quality in litchi cv. ‘Mandraji’. Acta Hortic 2018; 1211: 1–6.

Singh

Kumar

Kundu

, et al. Split applications of GA3: effective to improve growth, yield and quality of cape gooseberry (Physalis peruviana L.). Ecol Environ Conserv 2022; 28: 863–868.

Ozturk

Akkaya

Aglar

, et al. Effect of preharvest biofilm applications regimes on cracking and fruit quality traits in ‘0900 Ziraat’sweet cherry cultivar. BMC Plant Biol 2024; 24: 74.

Sen

Yilmaz

Ozturk

. Effects of 1-methylcyclopropene, methyl jasmonate and salicylic acid on physicochemical properties and wooliness of nectarine fruit during cold storage. BMC Plant Biol 2024; 24: 1205.

10.

Ozturk

Karakaya

Aglar

, et al. Impacts of methyl jasmonate treatments on quality properties and bioactive compounds of jujube fruit (Ziziphus jujuba) during cold storage. BMC Plant Biol 2025; 25: 1064.

11.

Wasternack

. Jasmonates: an update on biosynthesis, signal transduction and action in plant stress response, growth and development. Ann Bot 2007; 100: 681–697.

12.

Reyes-Díaz

Lobos

Cardemil

, et al. Methyl jasmonate: an alternative for improving the quality and health properties of fresh fruit. Molecules 2016; 21: 67.

13.

Concha

Figueroa

Poblete

, et al. Methyl jasmonate treatment induces changes in fruit ripening by modifying the expression of several ripening genes in Fragaria chiloensis fruit. Plant Physiol Biochem 2013; 70: 433–444.

14.

Shil

Das

Rime

, et al. The signalling pathways and regulatory mechanism of jasmonates in fruit ripening. Acta Physiol Plant 2025; 47: 1.

15.

Wang

Shi

Liu

, et al. Effects of exogenous methyl jasmonate on quality and preservation of postharvest fruit: a review. Food Chem 2021; 353: 129482.

16.

Blanch

del Castillo

MLR

. Changes in strawberry volatile constituents after pre-harvest treatment with natural hormonal compounds. Flavour Fragr J 2012; 27: 180–187.

17.

Martínez-Esplá

Zapata

Castillo

, et al. Preharvest applications of methyl jasmonate (MeJA) in two plum cultivars. 1. Improvement of fruit growth and quality attributes at harvest. Postharvest Biol Technol 2014; 98: 98–105.

18.

Garrido-Bigotes

Figueroa

. Jasmonate metabolism and its relationship with abscisic acid during strawberry fruit development and ripening. J Plant Growth Regul 2018; 37: 101–113.

19.

Kumar

Mishra

Saxena

, et al. Inhibition of pericarp browning and shelf life extension of litchi by combination dip treatment and radiation processing. Food Chem 2012; 131: 1223–1232.

20.

Sarkar

Thongchi

Sema

, et al. Influence of post-harvest treatments on physiological loss in weight (PLW) and bio-chemical changes in Litchi cv. Shahi. Environ Ecol 2022; 40: 866–872.

21.

Sándor

Mihály

Nagy

, et al. Effects of storage conditions, cultivars, and production systems on fruit decay incidence of sour cherry (Prunus cerasus L.) fruit after shelf-life conditions. Agronomy 2024; 14: 2212.

22.

Ranganna

. Handbook of analysis and quality control for fruit and vegetable products. New Delhi: Tata Mc. Grow-Hill Ltd., 2010.

23.

Hortwitz

. Official methods of analysis. 13th ed. Washington DC: Association of official analytical chemist, 1980.

24.

Lane

Eynon

. Methods for determination of reducing and non-reducing sugars. J Sci 1923; 42: 32–37.

25.

Jones

Hughes

. Foliar ascorbic acid in some angiosperms. Phytochem 1983; 22: 2493–2499.

26.

Apak

Güçlü

Özyürek

, et al. Mechanism of antioxidant capacity assays and the CUPRAC (cupric ion reducing antioxidant capacity) assay. Microchim Acta 2008; 160: 413–419.

27.

Chongchatuporn

Ketsa

van Doorn

. Chilling injury in mango (Mangifera indica) fruit peel: relationship with ascorbic acid concentrations and antioxidant enzyme activities. Postharvest Biol Technol 2013; 86: 409–417.

28.

Kumari

Kundu

Mir

, et al. Pre-harvest spermine applications influences ripening, yield and quality attributes of Litchi (Litchi chinensis Sonn.) cv. Deshi. Acta Physiol Plant 2025; 47: 05.

29.

Jiang

Zhang

Joyce

, et al. Postharvest biology and handling of longan fruit (Dimocarpus longan Lour.). Postharvest Biol Technol 2002; 26: 241–252.

30.

Jiang

. Biochemical and physiological changes involved in browning of litchi fruit caused by water loss. J Hortic Sci Biotechnol 1999; 74: 43–46.

31.

Duan

Zhang

Feng

, et al. Octanal enhances disease resistance in postharvest citrus fruit by the biosynthesis and metabolism of aromatic amino acids. Pestic Biochem Physiol 2024; 200: 105835.

32.

Cao

Zheng

Yang

, et al. Effect of methyl jasmonate on quality and antioxidant activity of postharvest loquat fruit. J Sci Food Agric 2009; 89: 2064–2070.

33.

Giménez

Valverde

Valero

, et al. Postharvest methyl salicylate treatments delay ripening and maintain quality attributes and antioxidant compounds of ‘Early Lory’ sweet cherry. Postharvest Biol Technol 2016; 117: 102–109.

34.

Ozturk

Yildiz

Ozturk

, et al. Maintaining postharvest quality of medlar (Mespilus germanica) fruit using modified atmosphere packaging and methyl jasmonate. Lwt 2019; 111: 117–124.

35.

Ding

Wang

Gross

, et al. Reduction of chilling injury and transcript accumulation of heat shock proteins in tomato fruit by methyl jasmonate and methyl salicylate. Plant Sci 2001; 161: 1153–1159.

36.

Ding

Wang

Gross

, et al. Jasmonate and salicylate induce the expression of pathogenesis-related-protein genes and increase resistance to chilling injury in tomato fruit. Planta 2002; 214: 895–901.

37.

Ayala-Zavala

Wang

, et al. Methyl jasmonate in conjunction with ethanol treatment increases antioxidant capacity, volatile compounds and postharvest life of strawberry fruit. Eur Food Res Technol 2005; 221: 731–738.

38.

Jiang

Jin

Wang

, et al. Methyl jasmonate primes defense responses against Botrytis cinerea and reduces disease development in harvested table grapes. Scientia Hortic 2015; 192: 218–223.

39.

Wang

Zhang

Xie

, et al. Effects of preharvest methyl jasmonate and salicylic acid treatments on growth, quality, volatile components, and antioxidant systems of Chinese chives. Front Plant Sci 2022; 12: 767335.

40.

Choudhary

Sundareswaran

Devi

. Aspartame induced cardiac oxidative stress in Wistar albino rats. Nutr Clin Metab 2016; 30: 29–37.

41.

Cai

Cao

Yang

, et al. MeJA regulates enzymes involved in ascorbic acid and glutathione metabolism and improves chilling tolerance in loquat fruit. Postharvest Biol Technol 2011; 59: 324–326.

42.

Dong

Zhi

, et al. Effect of methyl jasmonate on reactive oxygen species, antioxidant systems, and microstructure of Chinese winter jujube at two major ripening stages during shelf life. J Hortic Sci Biotechnol 2016; 91: 316–323.

43.

Huang

Shang

, et al. Effect of methyl jasmonate on the anthocyanin content and antioxidant activity of blueberries during cold storage. J Sci Food Agric 2015; 95: 337–343.

44.

Orozco-Cardenas

Ryan

. Hydrogen peroxide is generated systemically in plant leaves by wounding and systemin via the octadecanoid pathway. Proc Nat Acad Sci 1999; 96: 6553–6557.

45.

Gechev

Gadjev

van Breusegem

, et al. Hydrogen peroxide protects tobacco from oxidative stress by inducing a set of antioxidant enzymes. Cell Mol Life Sci 2002; 59: 708–714.

46.

Wang

Jin

Cao

, et al. Methyl jasmonate reduces decay and enhances antioxidant capacity in Chinese bayberries. J Agric Food Chem 2009; 57: 5809–5815.

47.

Flores

del Castillo

MLR

. Influence of pre harvest and postharvest methyl jasmonate treatments on flavonoid content and metabolomic enzymes in red raspberry. Postharvest Biol Technol 2014; 97: 77–82.