Effect of geospatial conditions and time of panicle emergence on the physiology and sensory attributes of mango var. alphonso

Introduction

Mango (Mangifera indica L.) is one of the most important tropical fruit crops cultivated across diverse agro-climatic regions, with India being the world's largest producer. Among commercial cultivars, Alphonso is highly prized for its superior flavour, aroma, colour, and market value. However, the expression of these quality attributes is strongly influenced by environmental conditions prevailing during flowering, fruit development, and ripening (Singh et al., 2021; Patel et al., 2023) [19,13] . Fruit quality is determined by the interaction between genetic potential and environmental factors such as temperature, rainfall, relative humidity, altitude, and soil fertility, which regulate physiological processes including photosynthesis, respiration, assimilate partitioning, and synthesis of flavour and colour compounds (Lal et al., 2020; Kumar et al., 2022) [10,9] . Consequently, mangoes produced in different geographical locations often exhibit considerable variation in physical, biochemical, sensory, and postharvest characteristics (Rajan et al., 2021; Sharma et al., 2024) [14,18] . Altitude influences temperature regimes, radiation intensity, and soil properties, thereby affecting fruit maturation, respiration, colour development, and storage behaviour (Kumar et al., 2022) [9] . Similarly, temperature, rainfall, and humidity significantly influence fruit growth, ripening, shelf life, and overall quality (Lal et al., 2020; Singh et al., 2021) [10,19] . In addition to environmental factors, flowering phenology plays a crucial role in determining fruit quality. Mango trees often produce multiple flowering flushes, exposing fruits from different panicle emergence periods to varying climatic conditions during development. As a result, earlyand late-emerged panicles may differ significantly in fruit size, dry matter accumulation, sugar content, colour, sensory quality, and shelf life (Jameel et al., 2018; Patel et al., 2023; Rajan et al., 2021; Sharma et al., 2024) [6,13,14,18] . Consumer acceptance of mangoes largely depends on appearance, colour, texture, aroma, taste, and overall eating quality, all of which are influenced by environmental conditions and fruit developmental history (Kumar et al., 2022; Sharma et al., 2024) [9,18] . Furthermore, location-specific climatic conditions affect respiration rate, ripening behaviour, and storability, making such information valuable for growers, traders, and exporters seeking to maximize fruit quality and market returns (Lal et al., 2020) [10] . Despite the recognized importance of geospatial factors and flowering phenology, information on their combined influence on the physiological and sensory quality of Alphonso mango under the agro-climatic conditions of southern India remains limited. Therefore, the present study was undertaken to evaluate the effects of altitude, temperature, rainfall, relative humidity, soil nutrient status, and panicle emergence timing on the physiology, sensory attributes, and shelf life of Alphonso mango. The findings will contribute to location-specific production strategies, improved harvest management, enhanced fruit quality, reduced postharvest losses, and greater profitability for mango growers (Bally, 2021; Crane and Balerdi, 2022; Litz, 2020) [1,3,12] .

Material and Methods

The experiment was conducted across four geographically distinct locations, namely Bengaluru, Chikkaballapura, Hogalgere, and Ramanagara, situated at altitudes of 930, 865, 836, and 747 m above mean sea level, respectively. These locations differed considerably in their geospatial and agro-climatic characteristics. At each location, mango panicles were tagged according to their time of emergence using colour-coded tags: white for early-emerged panicles, yellow for mid-emerged panicles, and pink for late-emerged panicles. Tagging was carried out at intervals of 10-15 days as successive flowering flushes emerged. Fruits from tagged panicles were harvested upon attaining optimum physiological maturity for subsequent evaluation (Table 1). Mature fruits of mango cv. Alphonso were harvested carefully, sorted to remove damaged or defective fruits, and disinfected using 200 ppm sodium hypochlorite solution.

The fruits were then pre-cooled, and de-sapping was performed by trimming the fruit stalk to a length of 0.6-1.0 cm, followed by placement in de-sapping trays for approximately four hours at ambient conditions to facilitate complete latex drainage. Ripening was induced using a portable ethylene gas can (Make: Chemtron; Model: Ripelene-6) in a ripening chamber maintained at room temperature (28 °C). The ripened fruits were subsequently utilized for the experimental studies. Data were analysed using a Completely Randomized Design (CRD).

Physiological loss in weight (PLW)

PLW was determined using a high-precision electronic balance with an accuracy of 10 mg (Make: Sartorius, Germany; Model: GE812). Initial fruit weights were recorded prior to storage, and subsequent measurements were taken at three-day intervals throughout the storage period. The cumulative physiological loss in weight was then calculated and expressed as a percentage using the standard formula.

The fruits of known volume were enclosed in a hermetic container for specified time and head space gas concentration of CO₂ was measured by an auto oxygen/carbon dioxide analyzer (Make: Quantek, Model: 902D Dual track) and direct reading was noted down from the instrument screen and was calculated using the following formula.

Sensory qualities

The organoleptic evaluation of mango fruits were conducted on the basis of appearance, colour, texture, aroma, taste and overall acceptability by a semi trained panel using a 5-point rating scale as laid out by Lawless and Heymann (1999) [32] .The score used for assessing the mango fruit is indicated as follows 5-Like; 4-Like slightly; 3-Neither like nor dislike; 2-Dislike slightly; 1-Dislike.

Results and Discussion

Physiological loss in weight (PLW%) Physiological loss in weight (PLW) during storage was primarily attributed to continuous respiration and transpiration processes (Table 2). Fruits from Ramanagara recorded higher PLW, which may be associated with the relatively higher temperatures prevailing during harvest and storage, along with lower relative humidity (50.38%), resulting in increased moisture loss. In contrast, fruits from Hogalgere exhibited the lowest PLW due to the comparatively lower storage temperature (27 °C), higher relative humidity (63.27%), and greater dry matter content, which collectively reduced respiratory and transpirational losses. Fruits from the first week of panicle emergence also showed the lowest PLW, indicating better storage performance. These findings corroborate earlier reports by Burdon et al. (2004) [2] and Spadaro et al. (2010) [20] , and are further supported by recent studies demonstrating that lower storage temperatures, higher relative humidity, and greater dry matter accumulation effectively minimize postharvest weight loss and maintain fruit quality during storage ( [11,15] . [4,5] . Fruits from Hogalgere exhibited the lowest respiration rate (Fig. 1), which may be attributed to the comparatively lower storage temperature and the higher dry matter content of the fruits. Environmental conditions during fruit development also influence respiratory activity; fruits exposed to moderate field stress often exhibit reduced respiration and moisture loss during storage (Karabacak and Karabacak, 2019) [7,8] . Furthermore, fruits from later-emerged panicles showed higher respiration rates than those from earlyemerged panicles, owing to enhanced metabolic activity involving the breakdown of starch, sugars, and organic acids into simpler compounds such as carbon dioxide and water. Since respiration rate is inversely related to storage life, fruits with higher respiration rates generally exhibit shorter shelf-life. A typical climacteric respiratory pattern was observed across all locations and harvest periods. Respiration initially declined to a pre-climacteric minimum, followed by a rapid increase to the climacteric peak and a subsequent decline during senescence (Sen et al., 2012) [16,17] . As respiration is regulated by enzyme-mediated metabolic reactions that are highly temperature-dependent, variations in storage temperature likely contributed to the observed differences in respiratory behaviour. Similar observations have been reported in earlier studies (Devanesan et al., 2011; Karabacak and Karabacak, 2019; Sen et al., 2012) [4,5,7,8,16,17] and are supported by recent findings indicating that lower storage temperatures and reduced metabolic activity effectively suppress respiration and prolong postharvest life in mango and other climacteric fruits (Li et [11,21,15] .

Sensory attributes

Sensory evaluation clearly demonstrated that both geospatial conditions and panicle emergence timing significantly influenced the sensory quality of Alphonso mango fruits during storage (Fig. 2). At the edible ripe stage (3 days of storage), fruits from Chikkaballapura recorded the highest scores for appearance (4.97), colour (4.98), and texture (5.00), while fruits from Hogalgere exhibited superior aroma (4.98), taste (5.00), and overall acceptability (5.00). Across all sensory attributes, fruits originating from the first week of panicle emergence consistently recorded the highest scores, with appearance (4.79), colour (4.79), texture (4.95), aroma (4.96), taste (4.95), and overall acceptability (4.97). As storage progressed, fruits from Hogalgere maintained superior sensory quality and exhibited the highest retention of appearance (4.28), colour (4.22), texture (3.70), aroma (3.51), taste (3.45), and overall acceptability (3.96) even after 15 days of storage. In contrast, comparatively lower scores were observed in fruits from Chikkaballapura, Bengaluru, and Ramanagara for specific sensory attributes. Similarly, fruits derived from early-emerged panicles consistently retained better appearance, colour, texture, aroma, taste, and overall acceptability throughout storage compared with fruits from mid-and late-emerged panicles (Fig. 3). These findings indicate that favourable geospatial conditions and early panicle emergence contribute significantly to enhanced sensory quality and improved storage performance of Alphonso mango fruits.

Correlation

The correlation analysis revealed significant relationships between geospatial factors and the postharvest physiological characteristics of Alphonso mango (Table 3). Physiological loss in weight (PLW) showed significant positive correlations with relative humidity (r=0.84), maximum temperature (Γ=0.72), and respiration rate (r=0.99), indicating enhanced moisture loss under conditions promoting higher metabolic activity. Respiration rate was positively correlated with relative humidity (r=0.74) and maximum temperature (r=0.64), suggesting increased fruit metabolism under warmer and more humid conditions. Shelf life exhibited a significant positive correlation with relative humidity (Γ=0.86) and altitude (r= 0.53), whereas it was negatively correlated with maximum temperature (r=-0.68), physiological loss in weight (Γ=-0.98), and respiration rate (r=-0.94). These results indicate that elevated respiration and moisture loss accelerated fruit senescence and reduced storage life. Overall, the study demonstrates that geospatial conditions substantially influence postharvest physiology, with favourable environmental conditions contributing to reduced metabolic activity, lower weight loss, and extended shelf life of Alphonso mango fruits.

Conclusion

This study conclusively establishes that geospatial heterogeneity and panicle emergence phenology exert a profound influence on the postharvest physiology, sensory excellence, and storage potential of Alphonso mango. Distinct location-specific variations in respiration rate, physiological loss in weight, shelf life, and organoleptic attributes underscore the pivotal role of altitude and prevailing agro-climatic conditions in modulating fruit quality. Fruits harvested from Hogalgere consistently exhibited superior sensory attributes, lower metabolic activity, and enhanced storability, whereas those from Ramanagara displayed accelerated respiration and reduced shelf life. Furthermore, fruits originating from earlyemerged panicles demonstrated markedly superior sensory quality and storage performance compared with those from later flowering flushes. The strong correlations observed between geospatial variables and postharvest traits reaffirm that environmental conditions prevailing during fruit development govern subsequent ripening behaviour and quality retention.

Collectively, these findings provide compelling evidence that the interplay between production environment and flowering phenology is a decisive determinant of Alphonso mango quality. The study offers valuable insights for precision orchard management, optimized harvest scheduling, and quality-oriented production strategies aimed at enhancing marketability, reducing postharvest losses, and sustaining premium fruit quality across diverse growing environments.

Acknowledgement

AcknowledgementAuthors are thankful to University of Horticultural Sciences, Bagalkot, and progressive mango grower Mr. Pranesh from Ramanagara and Department of Horticulture, Government of Karnataka for extending facilities for the research.

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