According to the indicators of quality, it appears that the mango trees had different responses to the foliar and soil applications of micronutrients.
Number of fruits per panicle
During the research work, it became evident that the quantity of fruits produced by individual trees significantly contributed to the overall number of fruit yield per plant, reaching its peak at 2.10 per plant after treatment T9. This aligns with similar observations in guava by
Trivedi et al., (2012) and
Rajkumar et al., (2014). Analysis of Table 1 reveals that the maximum number of fruits per panicle (2.10) was recorded under T9, involving the application of 125 grams of borax to the soil followed by a 0.2 per cent borax foliar application. Additionally, T8, which included the application of 125 grams of ZnSO
4 to the soil followed by a 0.4% ZnSO
4 foliar application, resulted in 2.05 fruits per panicle. Conversely, the minimum number of fruits per panicle (1.67) was observed under T10 (Control). The application of boron was found to expedite the growth of differentiated inflorescence, leading to an increased number of fruits per panicle. These outcomes are in line with similar findings in guava reported by
Badal and Tripathi (2021b).
Average fruit weight (g)
Table 1 reveals significant variations in average fruit weight across different treatments. The highest mean fruit weight (368 g) was observed with T9 (125 grams of borax applied to the soil and 0.2% borax foliar application), closely followed by T7 (125 g of FeSO
4 to the soil and 0.4% FeSO
4 foliar application) with a weight of 365 g. Conversely, the lowest average fruit weight (346 g) was observed in the control group (T10). Micronutrient application, particularly at higher concentrations, played a pivotal role in enhancing fruit quality by catalyzing various physiological processes. The foliar spray of micronutrients not only mitigated nutritional deficiencies but also bolstered fruit weight by facilitating the efficient uptake of macronutrients in mango plant tissues and organs. The findings align with previous studies conducted by
Asad (2013) on pears and
Dhaker et al., (2013) on bael. Except treatments T6, T8 and T7, T9 consistently yielded the highest average fruit weight (368 g), establishing statistical significance. In contrast, the control group (T10) consistently exhibited the lowest fruit weight. The beneficial effects of micronutrients such as zinc, promoting starch formation; iron, aiding cell growth and division; and boron, facilitating carbohydrate transport, are implicated in these outcomes. This synergy is supported by earlier research in mango cultivation by
Dutta (2004),
Nehete et al., (2011) and
Bhatt et al., (2012). The combined application of boron, iron and zinc (B+Fe+Zn) appears to have a cumulative positive impact on fruit weight, as suggested by a previous study (2012).
Total soluble solids (°Brix)
Table 1 reveals that the highest total soluble solids (TSS) value of 23.4 °Brix was observed in treatment T9, involving the application of 125 grams of borax to the soil followed by a 0.2% foliar application of borax. Following closely, treatment T7, which included the application of 125 g of FeSO4 to the soil followed by a 0.4% foliar application of FeSO
4, exhibited a TSS value of 23 °Brix. Conversely, the lowest TSS value of 17.6 °Brix was recorded in the control group (T10). The improvement in TSS can be linked to the regulatory role of zinc, promoting auxin-induced cell expansion, water and solute accumulation in the vacuole and boron’s influence on sugar translocation. Micronutrients, such as zinc and boron, enhance enzyme activity and carbohydrate accumulation during photosynthesis, facilitating sugar transport within plants. These results align with previous findings by
Hamouda et al., (2016). Notably, treatment T9 significantly increased TSS (23.4 °Brix) in mango fruit, comparable to treatments T6 (23 °Brix), T8 (22.9 °Brix), T7 (22.2 °Brix), T5 (22.1 °Brix) and T4 (21.8 °Brix). In contrast, the control (T10) exhibited the lowest reading (17.6 °Brix). The heightened TSS in T9 may be attributed to zinc’s promotion of tryptophan, a precursor to auxin, crucial for protein synthesis, sugar metabolism and structural integrity. Additionally, boron’s association with the cell membrane, potentially interacting with sugar molecules, may facilitate their passage, explaining the increased TSS. This aligns with similar findings in mango
(Bhowmick and Banik, 2011;
Nehete et al., 2011; Bhatt et al., 2012; Bhowmick et al., 2012), ber
(Meena et al., 2006) and aonla
(Singh et al., 2001; Vishwakarma et al., 2013; Chandra and Singh, 2015), as reported by
Shukla et al., (2011).
Titrable acidity (%)
Remarkably, treatment T9 yielded fruit with the lowest acidity level (0.20%), while the control treatment (T10) resulted in the most acidic fruit, registering at 0.34%. This variation may be attributed to boron’s facilitation of nutrient transport, including phosphorus, starch and sugar, within the framework of carbohydrate metabolism. As a borate complex, boron enhances the ease of sugar transfer across the cell membrane.
Chandra and Singh’s (2015) study on aonla aligns with our findings. In addition to boron’s impact on acidity, zinc’s influence on glucose-6 and phosphate dehydrogenase enzymes could contribute to acidity reduction. On the other hand, iron and manganese, by diminishing respiration and engaging in enzymatic activities, may also contribute to acidity reduction.
Balakrishnan (2001) discovered a similar outcome in guava, demonstrating that a foliar treatment combining 0.1% B, 0.25% Mn, 0.25% Fe and 0.25% Zn resulted in the lowest acidity percentage. Our findings find resonance with previous research, such as that conducted by
Bhowmick and Banik (2011); Nehete et al., (2011); Singh et al., (2013) in mango and
Meena et al., (2006) in ber. In mango, the present study’s conclusions align with those of prior research.
Reducing sugar (%)
The greatest decrease in sugar percentage was seen with treatment T9. This treatment was statistically equal to treatment T8, which had a value of 10.2%. Despite this, the control group had a little reduction in sugar (6.6%). Both the soil and the foliar spray of micronutrients contained more reducing sugar. Plants needed zinc and auxin to boost enzyme activity. Also catalyzes plant oxidation-reduction. The climacteric properties of mangoes lead respiration to fluctuate substantially throughout growth. Starch is converted to glucose via dynamic metabolic processes. The metabolism breaks down complex food into smaller ones. Fe seems to have produced taste-enhancing proteins. Zn aids hexokinase, cellulose and carbohydrate-to-sugar conversion. The results of
Anees et al., (2011); Nehete et al., (2011); Bhatt et al., (2012) and
Jat and Kacha (2014) in mango and guava are similar.
Non-reducing sugar (%)
Data (Table 1) scores for notably most non-decreasing sugar percent (12.1%) registered with remedy T9 which changed into at par with remedies
viz. T6 foliar utility of borax 0.2%, T8 soil utility of Znso4 one hundred twenty-five g observed with the aid of using the foliar utility of Znso4 0.4% and T7 at the same time as minimal non-decreasing sugar per cent (9.0%) changed into stated below control.
Total sugar (%)
Throughout the experiment, treatment T9 was used, which resulted in the production of mango fruit with a maximum total sugar content of 21%. Based on the findings of the experiment, it was determined that treatment T9 was statistically equivalent to treatment T6 (20.9%). The amount of total sugar in the mango fruit was the lowest among those that were monitored (15.7%). The catalytic impact of micronutrients, particularly in large doses, may explain fruit sugar increases. The observed elevation in total soluble solids (TSS) and total sugars could be attributed to an augmented mobilization of carbohydrates from the source to the sink (fruits) induced by auxin. This phenomenon may be associated with an increase in α-amylase activity, stimulated by boron application, leading to the conversion of starch into sugars and an enhancement in TSS content. Similar findings have been reported by various researchers, including
Shukla et al., (2011) in aonla,
Gupta et al., (2022) in litchi,
Tsomu and Patel (2019) in mango cv. Mallika,
Goswami et al., (2014) in guava and
Tripathi et al., (2018).
Ascorbic acid (mg/100 g pulp)
Throughout the course of the experiment, treatment T9 was used, which resulted in the production of mango fruit with a maximum Ascorbic content of 26.3 g/100 pulp. Based on the findings of the experiment, it was determined that treatment T9 was statistically equivalent to treatment T6 (25.6 g/100 pulp). The amount of Ascorbic acid in the mango fruit was the lowest among those that were monitored (15.7/100 g pulp). This rise in ascorbic acid levels could be the consequence of favorable metabolic activity involving specific enzymes and metallic ions under the impact of micronutrients like boron, which would have led to increased ascorbic acid synthesis. The constant synthesis of glucose-6-phosphate, which is regarded to be the precursor of vitamin C, during the fruits’ growth and development may be the cause of an increase in ascorbic acid content. Numerous researchers, including
Dubey et al., (2017) for the strawberry cv. chandler and
Kumar and Singh (2019) in the mango cv. Amrapali, have found similar results.
Shelf life (Days)
The consequences of the exercise showed that the shelf life of mango fruit could be greatly increased (to 13 days) by using the treatment T9 It was numeric equal to treatments T6 and T8 with numerical data of 12.6 days and 12.3 days, respectively; however, the control had a shorter shelf life (9.8 days) (T10). This might be the result of a risen concentration of boron in the central lamella of the cell wall. Boron gives the cell wall its physical strength and boosts the development as well as the look of the colour of the fruit. Several fruits and vegetables contain significant amounts of boron in their natural composition. The research that was done on mango by
Bhatt et al., (2012); Singh et al., (2012) and
Kumar et al., (2019) have found a similar result.
Fruit yield per tree (kg)
Table 1 illustrates the notable fruit yield variations observed throughout the experiment; with treatment T9 exhibiting the highest yield (78.3 kg per tree). This superiority persisted despite the application of treatment T9. Over the trial year, treatment T9 consistently matched the fruit yield of T6 (77.1 kg per tree), T8 (75.4 kg per tree) and T7 (74 kg per tree). The enhanced yield associated with T9 is attributed to micronutrients, known for their roles in plant development, flowering, growth and photosynthesis. This finding aligns with previous studies on mangoes
(Singh et al., 2003; Saran and Kumar, 2011;
Nehete, 2011;
Singh and Varma, 2011;
Bhatt, 2012;
Bhowmick, 2012) and guavas
(Jat and Kacha, 2014;
Gaur et al., 2014).
