Influence of rejuvenation practices on flowering behaviour of Alphonso mango (Mangifera indica L.) under Konkan agro-climatic conditions

Introduction

Mango (Mangifera indica L.), popularly known as the "King of Fruits," is one of the most important commercial fruit crops cultivated in India. Among the numerous cultivars grown, Alphonso occupies a prominent position owing to its exceptional fruit quality, unique flavour, attractive saffron-coloured pulp and high export potential. The Konkan region of Maharashtra is recognized as the natural home of Alphonso mango, where the crop thrives under humid coastal climatic conditions characterized by moderate temperatures, high relative humidity and well-distributed rainfall. Furthermore, the red lateritic soils of the Konkan region, which are slightly acidic, well-drained and rich in iron and aluminium oxides, provide an ideal edaphic environment for successful cultivation of Alphonso mango. A substantial proportion of Alphonso orchards in the Konkan region consists of old and senile trees exhibiting declining productivity, poor canopy architecture, reduced fruit retention and inferior fruit quality. Rejuvenation through strategic pruning has emerged as an effective orchard management practice to restore tree vigour, improve canopy efficiency and enhance productivity in such aged orchards. However, rejuvenated trees often experience substantial fruit drop during the early stages of fruit development, thereby limiting their yield potential.

Materials and Methods

The experiment was conducted in 35 years old Alphonso mango orchard at the centre of excellence for mango Dapoli during the two seasonal consecutive trials in the years 2023-24 and 2024-25. The experiment was laid out in a Factorial Randomized Block Design (FRBD) with three replication. C6 n-ATCA 10% and folic acid 0.2% @ 1 ml/l (Pea stage), 1.5 ml/l (Marble stage) and 2 ml/l (Egg stage) C7 Control

At the time of optimum flowering stage on the experimental tress, the intensity of flowered shoots were counted and calculated by following formula. These values were transformed to arc sine values and considered for statistical analysis.

Flowering intensity (%) = (No. of flowering shoots) (Total No. of shoots) X 100

Hermaphrodite flowers per panicle

The number of hermaphrodite flowers per panicle was recorded by counting flowers on four tagged panicles selected from each of the four cardinal directions of every tree and the average value was calculated.

Male flowers per panicle

At the time of full bloom, male flowers were counted from the previously selected panicle. Average values for these panicles were taken to represent the number of male flowers per panicle.

Total numbers of flowers per panicle

The number of total flowers per panicles were obtained by taking sum of male and hermaphrodite flowers.

Percent hermaphrodite flowers per panicle

Total number of hermaphrodite flowers appear per panicle were recorded and their percentage in total number of flowers was calculated by following formula.

Hermphrodite flower (%) = (Total no of hermaphrodite flowers per panicle) (Total no of flowers per panicle) X 100

Percent Male flowers per panicle

Total number of male flowers appear per panicle were counted and their percentage in total number of flower was calculated by following formula.

Male flower (%) = (Total no of male flowers per panicle) (Total no of flowers per panicle) X 100

Sex ratio (Male: Hermaphrodite Flowers)

The ratio of number of male flowers to the number of hermaphrodite flowers in the panicle was worked out by following formula.

Sex Ratio (M: H) = (Total no of male flowers per panicle) (Total no of Hermaphrodite flowers per panicle)

Statistical Analysis

The collected data were statistically analysed following the method suggested by Panse and Sukhatme (1985) [4] . The standard error of mean (S.E.) was calculated and the critical difference (C.D.) at the 5% level of significance was determined wherever the results were found significant. The percentage data were subjected to arc-sine transformation prior to statistical analysis.

Results

Flowering parameters

Effect of rejuvenation practice in old and senile orchard of Alphonso mango significantly change the flowering parameters of tree that is total number of flowers, number of male flowers, number of hermaphrodite flowers, sex ratio etc.

The data revealed that Factor A (Rejuvenation practice)

shows a significant influence on flowering intensity of mango during both years of investigation as well as in pooled analysis. Among the two rejuvenation practice, P 1 recorded significantly higher flowering intensity than nonrejuvenated trees P 2 . During 2023-24, P 1 exhibited 62.19% flowering intensity (52.06) compared to 58.89% (50.12) under P 2 . Similarly, in 2024-25, P 1 recorded 76.19% (60.79) flowering intensity, whereas P 2 registered 71.96% (58.03).

C6-n-ATCA @ 1ml/l (50% flowering), 1.5ml/L (Marble stage), and 2ml/l (Egg stage) C3-KNO3 @ 1% C7-Control C4-CPPU @ 3% The pooled mean also followed the same trend, with P 1 producing 69.19% (56.28) flowering intensity as against 65.43% (53.99) under P 2 . Similar findings have been reported by Shinde et al. (2003) [5] , who observed improved flowering and productivity in rejuvenated Alphonso mango orchards due to better light distribution within the canopy. Likewise, Gopu et al. (2014) [2] reported that canopy management practices significantly enhanced flowering in Alphonso mango by improving canopy microclimate and shoot vigour. Furthermore, Grechi et al. (2021) [3] demonstrated that pruning intensity and severity influence flowering processes in mango through modifications in canopy structure and resource allocation. The lower flowering intensity recorded under P 2 may therefore be associated with comparatively less favourable canopy conditions and reduced stimulation of productive shoot growth.

Hermaphrodite flowers per panicle

Total number of hermaphrodite flowers per panicle was significantly influenced by rejuvenation practices during both years of study as well as in pooled analysis. and the interaction effect on hermaphrodite flower production were found to be non-significant during both years and in pooled analysis. The significantly higher number of hermaphrodite flowers per panicle observed under P 1 may be attributed to the beneficial effects of rejuvenation pruning in improving canopy structure, enhancing light penetration, and promoting vigorous shoot growth. Pruning removes old, senescent, and unproductive branches, thereby stimulating the emergence of healthy shoots with greater physiological efficiency. Improved photosynthetic activity and better translocation of assimilates to developing floral buds may have favoured the formation of a higher proportion of hermaphrodite flowers. Hermaphrodite flowers are the functional flowers responsible for fruit set in mango, and their production is strongly influenced by the nutritional and physiological status of the tree. The enhanced canopy environment under rejuvenated trees likely improved the carbohydrate-tonitrogen balance and hormonal regulation, leading to increased differentiation of hermaphrodite flowers.

Conversely, the lower number of hermaphrodite flowers recorded under P 2 may be due to comparatively poor canopy illumination and reduced availability of assimilates for reproductive development. The present findings are in accordance with the reports of Shinde et al. (2003) [5] , who observed that rejuvenation pruning in old Alphonso mango orchards improved flowering characteristics by enhancing canopy light interception and shoot vigour. Similar results were reported by Gopu et al. (2014) [2] , who noted that canopy management practices in Alphonso mango improved flowering behaviour and reproductive efficiency. Grechi et al. (2021) [3] also demonstrated that pruning-induced modifications in canopy architecture influence flowering processes and reproductive development in mango trees.

Male flowers per panicle

Number of male flowers per panicle was significantly influenced by rejuvenation practices during both years of study and in the pooled analysis. Among the rejuvenation treatments, P 1 recorded significantly higher numbers of male flowers per panicle than non-rejuvenated tree P 2 . During 2023-24, P 1 produced 1164.48 male flowers per panicle, whereas P 2 recorded 800.05 male flowers per panicle. Similarly, in 2024-25, P 1 registered 1287.10 male flowers per panicle, while P 2 recorded 901.24 male flowers per panicle. The pooled mean also revealed the superiority of P 1 with 1225.79 male flowers per panicle, compared to 850.64 male flowers per panicle under P 2 . The effect of Factor B and the interaction effect on male flower production was found to be non-significant during both years and in pooled analysis. The increase in flower production following rejuvenation pruning is consistent with the findings of Shinde et al. (2003) [5] , who reported enhanced flowering behaviour and canopy productivity in rejuvenated Alphonso mango orchards. Similar observations were made by Gopu et al. (2014) [2] , who noted that canopy management practices improved flowering characteristics through better light distribution and physiological activity. Grechi et al. (2021) [3] further reported that pruning intensity significantly affects flowering processes in mango by altering canopy structure, source-sink relationships, and assimilate partitioning. It is noteworthy that although P 1 produced a higher number of male flowers, it also recorded a significantly greater number of hermaphrodite flowers per panicle. Therefore, the increase in male flowers reflects enhanced overall flowering rather than a reduction in reproductive efficiency. [5] , who observed that rejuvenation pruning in Alphonso mango improved flowering and productivity by enhancing canopy light interception and stimulating new shoot growth. Similar observations were reported by Gopu et al. (2014) [2] , who demonstrated that canopy management practices significantly increased flowering and reproductive performance in Alphonso mango. Furthermore, Grechi et al. (2021) [3] reported that pruning intensity and severity strongly influence flowering processes in mango through their effects on canopy structure, resource allocation and floral induction.

Total numbers of flowers per panicle

Percent hermaphrodite flowers

Percentage of hermaphrodite flowers per panicle was significantly influenced by rejuvenation practices during both years of study as well as in pooled analysis. Among the rejuvenation treatments, P 2 recorded a significantly higher percentage of hermaphrodite flowers per panicle compared to P 1 . During 2023-24, P 2 registered 7.76% hermaphrodite flowers, whereas P 1 recorded 6.16%. Similarly, during 2024-25, P 2 recorded 6.66% hermaphrodite flowers, which was significantly higher than 5.42% observed under P 1 . The pooled analysis also revealed the superiority of P 2 , with 7.06% hermaphrodite flowers per panicle, compared to 5.79% under P 1 . The effects of Factor B and the interaction effect (A × B) were found to be nonsignificant during both years and in pooled analysis. Although rejuvenation treatment P 2 recorded a significantly higher percentage of hermaphrodite flowers (7.06%) than P 1 (5.79%), P 1 produced a substantially greater number of hermaphrodite flowers per panicle (73.69). Thus, P 1 enhanced overall flowering capacity, whereas P 2 increased the relative proportion of hermaphrodite flowers among the total flowers produced.

Percent Male flowers

Percentage of male flowers per panicle was significantly influenced by rejuvenation practices during both years of investigation as well as in pooled analysis. Among the rejuvenation treatments, P 1 recorded a significantly higher percentage of male flowers per panicle compared to P 2 . During 2023-24, P 1 registered 93.84% male flowers, whereas P 2 recorded 92.50%. Similarly, during 2024-25, P 1 recorded 94.58% male flowers, which was significantly higher than 93.37% observed under P 2 . The pooled analysis also showed that P 1 maintained a significantly greater proportion of male flowers (94.21%) compared with P 2 (92.94%).The effects of Factor B and the interaction effect of factors were found non-significant during both years and in pooled analysis. In the present study, P 1 produced significantly higher numbers of total flowers (1299.48 flowers per panicle) and male flowers (1225.79 flowers per panicle) than P 2 (914.19 and 850.64 flowers per panicle, respectively). Consequently, the proportion of male flowers also increased under P 1 . The higher male flower percentage under rejuvenated trees may be associated with enhanced vegetative vigour and greater assimilate availability, which promoted prolific floral development. Similar observations have been reported in mango, where pruning and canopy management practices increased total flower production, with male flowers constituting the dominant floral type. Conversely, the lower percentage of male flowers recorded under P 2 was accompanied by a relatively higher proportion of hermaphrodite flowers. This suggests that although P 2 produced fewer flowers overall, a greater proportion of the floral buds differentiated into hermaphrodite flowers, resulting in a reduced male-to-hermaphrodite ratio. The findings are consistent with reports by Shinde et al. (2003) [5] and Gopu et al. (2014) [2] , who observed that rejuvenation pruning and canopy management significantly altered flowering behaviour and flower composition in Alphonso mango. Furthermore, Cavalcante (2022) [1] noted that flowering intensity and floral sex expression in mango are influenced by canopy conditions, carbohydrate reserves, hormonal balance and environmental factors, all of which may be modified by pruning practices.

Sex ratio (Male: Hermaphrodite flowers)

Sex ratio (M:H) was significantly influenced by rejuvenation practices during both years of study and in pooled analysis. Among the rejuvenation treatments, P 1 recorded a significantly higher sex ratio than P 2 . The effects of Factor B and the interaction effect (A × B) on sex ratio were found to be nonsignificant during both years and in pooled analysis. The significantly higher sex ratio (M:H) observed under P 1 was mainly due to the proportionately greater increase in male flower production compared to hermaphrodite flowers. Rejuvenation pruning stimulates vigorous vegetative growth and improves canopy architecture, leading to enhanced floral initiation and overall flower production. Since mango panicles naturally produce a predominance of male flowers, an increase in flowering intensity often results in a greater rise in male flowers than hermaphrodite flowers, thereby increasing the sex ratio. In the present investigation, P 1 produced significantly higher numbers of male flowers (1225.79 flowers per panicle) and hermaphrodite flowers (73.69 flowers per panicle) compared with P 2 (850.64 and 63.55 flowers per panicle, respectively). However, the increase in male flowers was proportionately greater than the increase in hermaphrodite flowers, resulting in a higher sex ratio under P 1 . This finding suggests that rejuvenation pruning enhanced overall floral development but favoured male flower production to a greater extent. The lower sex ratio recorded under P 2 indicates a relatively higher proportion of hermaphrodite flowers in relation to male flowers. Although P 2 produced fewer flowers overall, the reduced dominance of male flowers contributed to a comparatively lower male-to-hermaphrodite ratio. Sex expression in mango is regulated by several physiological factors, including carbohydrate reserves, hormonal balance, nutrient status and environmental conditions. Rejuvenation pruning alters these factors by improving light distribution, photosynthetic efficiency and assimilate partitioning within the canopy. Enhanced vegetative vigour under P 1 may have promoted abundant floral initiation, leading to increased production of male flowers and consequently a higher sex ratio. Similar observations have been reported by Shinde et al. (2003) [5] and Gopu et al. (2014) [2] , who found that pruning and canopy management practices significantly influenced flowering behaviour and flower composition in mango. Cavalcante (2022) [1] further reported that flowering intensity and floral sex expression are strongly affected by canopy microclimate, carbohydrate accumulation and hormonal regulation, which can be modified through rejuvenation practice.

Conclusion

Rejuvenation practice on Alphonso mango orchard improve flowering intensity of tree which results improvement in flowering behaviours, that is number of hermaphrodite flowers, male flowers, sex ratio (M:H) and overall development of fruits.

Acknowledgement

AcknowledgementThe authors are thankful to the Centre of Excellence for Mango Dapoli, Dr. B.S.K.K.V., Dapoli, and Chhatrapati Shahu Maharaj National Research Institute (SARTHI) for facilitating guidance and funds, respectively to conduct the investigation.

References

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3. Grechi I, Persello S, Boudon F, Normand F, et al. Pruning intensity and severity affect flowering processes in the mango tree. Acta Horticulturae. 2021;1346:63-70.
4. Panse VG, Sukhatme PV. Statistical methods for agricultural workers. New Delhi: ICAR; 1985.
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