The Role of Some Growth Stimuli on Mango Growth Performance

1-INTRODUCTION

The mango tree (Mangifera indica L.) is an evergreen species of the Anacardiaceae family and is regarded as one of the most major fruits in tropical and subtropical regions of the world. It may grow in a variety of soil and climate conditions(Alshallash et al., 2022), with a fruit area of 289 thousand acres and a yield of 1351316 tonnes, mangoes in Egypt rank third in terms of economic importance in the fruit trade after grapes and citrus (FAO, 2017).

Mangoes come in a wide range of varieties, all of which are high in nutrients and flavonoid antioxidants. Keitt cultivar has an oblong form and light to dark green skin, occasionally they have a yellow bluish shade and a tangy sweet flavour with a hint of honey (Lenucci et al., 2022). In addition, mango is consumed all above the world for its delectable flavour. As a result of its abundance in vitamins A and C, mango is frequently used in the production of juice, nectars, fruit leather and frozen pulp (Ernesto et al. 2018).

A natural polysaccharide produced by N-DE acetylating chitin, chitosan is a key component of the shells of crustaceans like crabs, shrimp, and crawfish (Maleki et al., 2022). Chitosan and its derivatives are non-toxic, friendly environment and have the potential to stimulate growth and increase yield in a variety of agricultural and horticultural applications (Mohan et al., 2022). It has a wide range of physio-chemical and biological properties because of its cationic nature, including antioxidant and antibacterial abilities; because it has positively charged amino group that interact with the negatively charged bacteria membrane (Aranaz et al., 2021), protect plants against oxidative stress and stimulate plant growth (Parvinet al., 2019).

Spermidine is an aliphatic polyamine, polycationic, has low molecular weight and classified as a secondary hormone messenger, it is involved in a variety of physiological processes in plants, including morphogenesis, floral differentiation and initiation, pollen viability, senescence prevention and biotic and abiotic stress reactions (Childs et al., 2003 and Chen et al., 2022). Without changing the amount of ethylene produced by the flower, polyamines increased pollen tube ovule penetration and postponed ovule senescence. Abbasi et al. (2017) discovered that spraying polyamine significantly boosted yield and yield component of mango trees.

Vermicomposting leachate contains (VCL) mineral content, humic acid, fulvic acid, vitamins, enzymes, amino acids, actinomycetes, as well as some growth hormones, it is a liquid phase, functions asa plant tonic (Suthar, 2010 and Arslan et al.., 2022). Foliar spray of VCL induced salt tolerance by reducing the accumulation of Na+, increased vegetative growth and productivity of fruit trees by about 15% also, increased disease resistance (Abd El–Hamied, 2018). Additionally, VCL increased the activity of antioxidant, enzymes, decreased oxidative stress and stopped electrolyte leakage (Siamak et al., 2017)

Potassium silicate is source of silicon and potassium that are soluble (El Kholyet al., 2018). It contributes a silica amendment in agricultural production systems primarily with added benefit of delivering trace levels of potassium (EL-Sayedet al., 2018). A suitable potassium nutrition helps many horticultural crops by increasing tree yields, fruit size, color, soluble solids and ascorbic acid concentrations (Kanai et al., 2007). Additionally, silicon is crucial for photosynthesis, nutrient and water intake, plant pigmentation and all types of cell division for raising and improving the resistance to biotic and a biotic challenges (Zargar et al., 2018). Therfore, the current study was conducted to investigate the effect of spraying mango trees cv. Keitt with various concentrations of chitosan, spermidine, vermicompost leachate, and potassium silicate.

2. MATERIALS AND METHODS

21. Location and date of the experiment

 Mango (Mangifera indica L.) is one of the most important fruit crops. The present experiment was carried out at two places i.e. Plant production department, Faculty of Agriculture, Saba Basha, Alexandria university, Egypt and a private orchard in Badr city, El-Beheira governorate, Egypt during 2020 and 2021, in order to study the horticultural characteristics of 10-year old Keitt cultivar grown in sandy soil using some growth stimuli (Chitosan, spermidine, vermicomposting leachate (VCL) extract and potassium silicate) to improve the growth behavior, nutritional status and productivity of mango trees. The selected trees were uniform in vigor as possible spaced 5x5, fertilization and other agricultural practices were the same for all trees, Physical and chemical properties of the experimental soil are presented in Table (1). The treatments were chitosan at 30, 60 and 90 ppm, spermidine at 5, 10 and 20 ppm, vermicomposting leachate  ( VLC at 10, 15, and 20%, potassium silicate at 400, 500 and 600 ppm and the control and sprayed four times a month before flowering, at the beginning of flowering, at full bloom and three weeks after the contract.

2..2The soil of the experimental site

Table (1): Some physical and chemical properties of the experimental soil

2.3 The chemical composition of the materials used in the research

• Chitosan

Formula: C6H11NO4X2, chitosan-from shrimp shells 75% AR (deacetylated), chitosan a linear polymer consisting of two subunits linked together: N-acetyl-D-glucosamine and D-glucosamine. Lot No.Sample COA- Code No.02697, LOBA CHEMIE PVT. LTD. ISO 9001-2015 CERTIFIED, India.

• • Spermidine

Spermidine (99%), Synonym(s):1, 8-Diamino-4-azaoctane, N-(3-Amino propyl)-1, 4-diaminobutane. Linear Formula: NH2(CH2)3NH(CH2) 4NH2- CAS Number:  124-20-9 EC Number: 204-689-0 M.W:145.25 Lot: A014080101, Sigma- Aldrich Company, India

.

•Vermicomposting leachate( VLC): the component of VCL illustrated in Table 2

Table (2): Characteristics of vermicomposting leachate obtained from cattle manure

• Potassium silicate

The formula can be written as K2O3Si, the compound consists of potassium oxide 10% and silicon oxide 25%. (Alpha Chemika Company - Batch No.: P 43256 Sr. No. AL 10332/02); company certified ISO 9001- 2008, made in India), M.W 154.28

Randomized Complete Block Design (RCBD) was used with three replicates (each duplicate is composed of three trees) and random distribution of factors.

2.4 Flowering characteristics

On March, 15 and 20 in 2020 and 2021, respectively; the number of flowers panicle for each replicate was counted also, panicle length (cm) and the percentage of hermaphrodite flowers /panicle was calculated as the following equation:

14Hermaphrodite flowers %per panicle=No. of perfect flowersTotal No. of flowers×100

2.4.1 Fruit set percentage were recorded as follow

The number of fruit set/tree was counted after 15 days of full bloom according to the following formula:

14Fruit set (%)=No. of retained fruitsNo.of perfect flowers×100

2.5 Yield and yield components:

At harvest time (September 22 and 25 in 2020 and 2021, respectively), yield (kg/tree) per each replicate was calculated by multiplying the number of fruits with average fruit weight, average fruit weight (g/ fruit) and the number of fruits/tree also, recorded.

2.5 The Chemical fruit characteristics

2.5.1 Total soluble solids (%)

The percentage of TSS was determined in mango fruit juice using a hand refract meter according to A.O.A.C (1995).

2.5.2 Total acidity (%)

The percentage of total acidity was colorimetrical measured based on estimated citric acid using five milliliters of the fruit juice of each fruit sample and titrated with sodium hydroxide solution of a known normality using phenolphthalein as an indicator (A.O.A.C., 2005). The results of these titrations were converted to percent of treatable acidity using the following equation: percent of treatable Where: 0.064= mille equivalent factor of citric acid.

2.5.3 Vitamin C (Ascorbic acid) (mg/ 100g pulp)

The ascorbic acid content of the juice was determined by titration with 2, 6 dichloro phenol-indo-phenol (A.O.A.C., 1995) and calculated as milli-grams per 100 ml of juice.

2.5.4 Total sugars (%)

Total sugars (%) were determined calorimetrically using phenol and sulphuric acid, according to Malik and Singh (1980) extracted from 5-gram fresh.

2.6 Leaf mineral compositions (N, P and K)

Samples of the third pairs of leaves from the base of none fruiting shoots were collected in mid -August in both seasons of the study. Samples of 40 leaves /tree were taken at random from the previously tagged shoots, the leaf samples were washed with tap water and distilled water then oven dried at 70°C to constant weight and then ground. To determine the leaf mineral contents, ground material of each sample was digested with H₂SO₄ and H₂O₂ according to  Wolf ) 1982). In the digested material, total nitrogen and phosphorus were determined colorimetrically (Evenhuis and De waard, 1980; Murphy and Riley, 1962), and potassium was determined by flame photometer as described by Chapman and Pratt (1978) and the concentrations of N, P and K were expressed as percent.

2.7 Statistical analysis

Results of the measured parameters were subjected to computerized statistical analysis using MSTAT package for analysis of variance (ANOVA) and means of treatments were compared using LSD at 0.05 according to Snedecor and Cochran  (1980).

3. RESULTS AND DISCUSSION

3.1 Effect of spraying chitosan, spermidine, vermicomposting leachate and potassium silicate treatments on the number of flowering panicle, panicle length (cm), the number of hermaphrodite flowers /panicle, and  hermaphrodite flowers/panicle (%) in Keitt mango cultivar  during 2020 and 2021 seasons

           Data presented in Table (3) showed that, 60ppm chitosan caused a significant increase in the number of flowering panicle and panicle length (cm) compared to the control. While, 30 ppm concentration caused a significant increase in the number of hermaphrodite flowers/ panicle compared to the control and 60 and 90 ppm concentrations, in the meantime, significant differences were found in hermaphrodite flowers (%) between 30, 60 and 90 ppm concentrations compared to the control. In the first season, significant increase in the number of flowering panicle was found between 60ppm concentration compared to 30 ppm concentration. 30 ppm concentration caused a significant increase in hermaphrodite flowers (%) compared to 90 ppm concentration, in the first season, in one side and compared to 60 and 90 ppm concentrations in the second season, in other side.

          As for spermidine in Table (3), 5, 10 and 15 ppm concentrations of spermidine caused a significant increase in the number of flowering panicle, hermaphrodite flowers /panicle and hermaphrodite flowers (%) compared to the control, except for 20 ppm concentration for the number of flowering panicle in the first season. 5 ppm concentration caused a significant increase in the panicle length compared to the control, in one side and compared to 10 and 20 ppm concentrations in the number of flowering panicle, in the second side.

            In Table (3), 20 % concentration of VCL caused a significant increase in the number of flowering panicle compared to the control and 10 and 15 % concentrations, in the first season, in one side and compared to control and 10 % concentration for panicle length in the two seasons in the other side. In the meantime, 20% concentration caused a significant increase in panicle length (cm) compared to the control and 10% concentration, in the two seasons. 10 % concentration caused a significant increase in the number of hermaphrodite flowers /panicle compared to the control and 20 and 15% concentrations. Significant increase was found in hermaphrodite flowers (%) between 10, 15 and 20 % concentrations compared to the control. In the second season, 15 and 20 % concentrations caused a significant increase in the number of flowering panicle compared to the control and 10 % concentration.

             As for potassium silicate in Table (3), in the first season, 500 and 600 ppm concentrations caused a significant increase in the number of flowering panicle compared to the control and 400 ppm concentrations. While, in the second season, significant differences were found between 500 and 600 ppm treatments compared to the control. In the first season, 500 and 600 ppm concentrations caused a significant increase in the panicle length (cm) compared to the control, while significant differences were found between 600 ppm concentration compared to 400 ppm concentration.

             These results are agreed with the findings of (Kasem and Fawzy, 2020), they found that, the foliar application of chitosan on olive significantly promoted the shoot length, length of inflorescence as well as number of flowers rather than the control. These results might be attributed to the positive action of spraying chitosan on enhancing cell division, the biosynthesis of organic foods and uptake of nutrients. Chitosan acts also as chelators to minerals and metals, also reports to bind mycotoxins and reduces the damage of the host tissues due to toxins and it has antimicrobial properties linked thus reducing fungal spoilage (El Hadramiet al., 2010). In the same line, Malik and Singh(2006), found that spraying polyamine markedly enhanced fruit set, fruit retention and size of fruits, whereas, polyamines utilized to regulate fruit development to reveal the flower buds and increase their numbers (Wolukau et al., 2004). Polyamines are implicated in a wide range of plant physiological processes such as flower differentiation and initiation, pollen viability and anti-senescence (Childs et al., 2003).

           In addition, Sathe and Patil (2014) recorded that, VCL is a good bio-fertilizer and tonic to mango, which increased the fruit production of mango. Use VCL as a liquid fertilizer provides the advantage of homogeneity, when applied to growth media (Quaik et al., 2012; Quaiket al., 2012). The hormonal concept of flowering in mango implies that cyclic synthesis of floral stimulus in leaves and the gap between the two cycles would decide flowering behavior of mango (Singhet al., 2001 ; Kumar and Reddy, 2008).

Abdel Gawad (2017) reported that potassium silicate increased the number of panicles per tree. Total number of flowers per panicle, number of male flowers and number of perfect (hermaphrodite) flowers and the sex ratio significantly improved with spraying potassium silicate. Similar findings were reported by (Singh et al., 2001 ; Kumar and Reddy, 2008), they found that spraying potassium silicate significantly accompanied with enhancing shoot length, number of leaves/ shoot and leaf area of mango trees.

Table (3): Effect of spraying chitosan, spermidine, vermicomposting leachate and potassium silicate treatments on the number of flowering panicle, panicle length (cm), the number of hermaphrodite flowers /panicle and hermaphrodite flowers/panicle (%) in keitt mango cultivar during 2020 and 2021 seasons

       Means followed by the same letter(s) within a separate column are not significantly different at 0.05 level of probability.

.2 Effect of spraying chitosan, spermidine, and vermicomposting leachate and potassium silicate treatments on fruit set (%), number of fruits/tree, total yield (kg) /tree, fruit weight (g) in Keitt mango cultivar during 2020 and 2021 seasons

             As for chitosan, the results in Table (4) showed that, in the two seasons, significant increase was found in fruit set (%), the number of fruits/tree, the total yield (kg) /tree between 30, 60 and 90 ppm concentrations compared to the control in. 30 ppm treatment caused a significant increase in fruit set compared to 60 and 90 ppm concentrations, in the second season only. Significant increase in the number of fruits/tree was found between 30 ppm treatment compared to 60 ppm and 90 ppm treatments. In the meantime, significant increase in total yield was found between 30 ppm concentration compared to 60 ppm and 90 ppm concentrations, in the first season and between 30 and 60 ppm concentrations compared to 90 ppm concentration, in the second season. Chitosan treatment at 30 ppm caused a significant increase in the fruit weight compared to the control and 60 and 90 ppm concentrations, in the first season, while in the second season, 30 and 60 ppm treatments caused a significant increase in fruit weight compared to the control.

             Data in Table (4) showed that, there were statistically significant differences in fruit set (%), the number of fruits per tree and total yield between 5, 10 and 20 ppm concentrations of spermidine compared to the control. In the meantime, there was significant increase in fruit set (%) between 5 and 10 ppm concentrations compared to 20 ppm concentration, in the first season, while, 5 ppm concentration caused a significant increase in fruit set (%) compared to 10 and 20 ppm concentrations, in the second season. In the two seasons, 5 ppm concentration caused a significant increase in the fruit weight compared to the control.

           The results for VCL in Table (4) showed that, in the two seasons, there were statistically significant differences in fruit set (%), the number of fruits per tree, total yield and fruit weight  between 10, 15 and 20 % concentrations of VCL compared to the control, except for 15% concentration in the second season. In the meantime, in the second season, there was significant increase in fruit set (%) between 10 % concentration compared to 15 and 20 %. There were significant differences among the three concentrations in the number of fruits, in the two seasons. In the meantime, there were statistically significant increase in the total yield between 20 % compared to 10 and 15% treatments, in the first season, while, in the second season, there were significant differences among the three concentrations.

            As for potassium silicate, the results in Table (4) showed that, there were significant differences between 400, 500 and 600 ppm concentrations of potassium silicate compared to the control in fruit set (%), the number of fruits per tree, total yield and fruit weight, except for 400 ppm concentration in the second season only. There were significant increase in the number of fruits per tree and total yield between 600 ppm concentration compared to 400 and 500 ppm concentrations, in the second season. 600 ppm concentration caused a significant increase in fruit weight compared to 400 ppm concentration in the two seasons.

            Saied and Radwan (2017) found that spraying ‘Succary’ mango trees with chitosan significantly accompanied with improving the percentage of fruit retention, yield (kg) and number of fruits/tree compared to the control treatment. This  may be due to the beneficial role of chitosan in stimulating the biosynthesis of natural hormones, nutrient uptake, photosynthesis, biosynthesis of plant pigments and sugars as well as protecting the plants from various stresses (Roshdy et al., 2011; Al- Wasfy , 2013; Kasem and Fawzy, 2020).

It has been reported by many authors that application with putrescine significantly increased the yield in mango (Burondkar et al., 2009;  Babu et al., 2017) and in date palm (Naser et al., 2016). Spraying of putrescine increased significantly fruit set %, fruit retention % and significantly reduced fruit drop percentage (Shabanet al., 2017). Polyamines as anti aging is reported to reduce the fruit drop and increase the yield (Aliet al., 2017), increase cell division which leading to improve weight and diameter of fruit (Ayad et al., 2011). The beneficial role of polyamines (phyto-hormone) due to the increase of free auxin levels in fruit petiole and inhibite ethylene production (Malik and Singh, 2006; Dutta et al., 2018).

VCL increased disease resistance capacity in many agricultural plants against various bacterial, vital and fungal diseases and these characteristics increased vegetative growth and productivity of fruit trees by about 15% (Suthar, 2010). Sathe and Patil (2014) mentioned that VCL is a good biofertilizers, that provide mango trees with most of the essential inputs for metabolism and growth.

It has been reported that the spraying of VCL increased significantly the number of fruits, fruit weight, pulp weight, pulp/fruit and the total yield (Abd El–Hamied, 2018; Sathe and Patil, 2014). Abdel Gawad (2017) found that the spraying of potassium silicate at different concentrations significantly gave the highest percentage of fruit set, number of fruits per tree, fruit weight and yield. Spraying mango trees with potassium silicate can overcome frost injury; improved flowering and number of panicles per shoot, sex ratio, fruit set, number of fruit per tree, fruit weight as well as yield per tree (Habasy, 2016).

Table (4): Effect of spraying chitosan, spermidine, vermicomposting leachate and potassium silicate treatments on fruit set (%), number of fruits/tree, total yield (kg) /tree and fruit weight (g) in Keitt mango cultivar during 2020 and 2021 seasons

              Means followed by the same letter(s) within a separate column are not significantly different at 0.05 level of probability.

3.3 Effect of spraying chitosan, spermidine, vermicomposting leachate and potassium silicate on TSS%, Total sugars %, Acidity % and Vitamin C )mg/ 100 ml() in Keitt mango cultivar during 2020 and 2021 seasons

            Data presented in Table (5) showed that, 30, 60 and 90 ppm concentrations of chitosan caused a significant increase in the TSS (%), total sugars (%) and vitamin C (mg/ 100ml) content compared to the control, except for 90 ppm concentration to TSS (%) in the second season. Significant increase was found between 30 ppm concentration compared to 60 ppm and 90 ppm, for the three properties, except for total sugars (%) in the first season. In contrast, 30, 60 and 90 ppm concentrations caused a significant decrease in fruit acidity (%) compared to the control, also significant differences were found among 30, 60 and 90 ppm concentrations.

           Data presented in Table (5) showed that, 5, 10 and 20 ppm concentrations of spermidine caused a significant increase in the TSS, total sugars, acidity and vitamin C compared to the control. Significant differences were found among the three concentrations for TSS (%), in the two seasons and in vitamin C content in the first season.

              The results shown in Table (5), 10 %, 15 % and 20 % of VCL caused a significant increase in fruit TSS, total sugars and vitamin C content compared to the control, except for 10% concentration to TSS, in the second season. Significant increase in fruit TSS and total sugars content was found between 20% concentration compared to 10 and 15% concentrations, while, significant differences were found among the three concentrations for vitamin C content. In contrast, 10 %, 15 % and 20 % concentrations caused a significant decrease in the fruit acidity (%) compared to the control, and significant differences were found among the three concentrations, in the two seasons.

           The results shown in Table (5), 400, 500 and 600 ppm concentrations of potassium silicate caused a significant increase in fruit TSS, total sugars and vitamin C content compared to the control. In the first season, significant differences were found among the three concentrations in total sugars and vitamin C content in the two seasons and in TSS (%) in the first season and the increase in fruit vitamin C content increased by increasing the concentration of potassium silicate. In contrast, the three concentrations caused a significant decrease in fruit acidity compared to the control, also, significant decrease was found between 600 ppm concentration compared to 400 and 500 ppm concentrations.            

           Saied and Radwan (2017) found that appliedSuccary mango trees with chitosan significantly improved fruit quality as decreasing total acidity % and increasing total sugars, total soluble solids and vitamin C. Malerba  and Cerana (2016) attributed the positive action of chitosan to induce numerous biological responses in plants such as stress resistance and increased productivity, which due to its chemical composition, it also, encourages the absorption of minerals and increases the process of cell division and elongation, which reflected in the quality of the plant. Guan et al. (2009) reported the role of chitosan, which enhances the photosynthesis process that positively correlated with the synthesis of sugars, polysaccharides and vitamins.

          Abo-El-Ez et al. (2019) treated mango cv. Alphonse trees with polyamine improved greatly the fruit quality, also these results are in agreement with the findings of (Malik and Singh, 2006; Shaban et al., 2017;  Aliet al., 2017; Akula Venu and Ramdevputra, 2018), they worked on mango. additionally, Ayad et al. (2011) mentioned that the foliar application of putrescine significantly increased fruit quality characteristics and this may be the role of putrescine which is as bio regulatory stimuli on enzymatic activity and translocation processes from leaves to fruits, linking or converting to other plant metabolites (Serafini-Fracassini and Del Duca, 2008).

Abd El–Hamied (2018) cleared that VCL treatment gave the lowest total acidity and increase in the proportions of sugars and TSS. Furthermore, several studies have hypothesized those physiological mechanisms through, which humic substances exert that their effects may depend on hormones and in particular, the presence of auxin or auxinlike components in their structure, So VCL enhances quality of fruits (Nardi et al., 2002).

Habasy (2016) found a significant improve in quality of the fruits in terms of increasing vitamin C content and decreasing total acidity when, treated Navel orange trees with potassium silicate. The same results are obtained by (El Kholy et al., 2018; Lokesh et al. (2020). In the meantime, Hanumanthaiah et al., (2015) reported that application of silicon and potassium aids in synthesis of sugars in the fruit and increased TSS, this may be due to the essential roles of silicon (Si) on improving growth (Ma, 2004), increasing activates of enzymes, protecting plants from aging and biosynthesis of carbohydrates (Ma and Takahashi,  2002).

Table (5): Effect of spraying chitosan, spermidine, vermicomposting leachate and potassium silicate on TSS%, Total sugars %, Acidity% and Vitamin C )mg/ 100 ml) in Keitt mango cultivar during 2020 and 2021 seasons

       Means followed by the same letter(s) within a separate column are not significantly different at 0.05 level of probability.                      

3.4 Effect of spraying chitosan, spermidine, vermicomposting leachate and potassium silicate treatments on leaf mineral compositions from N, P and K in Keitt mango cultivar during 2020 and 2021 seasons

          Data in Table (6), the application of 30, 60 and 90 ppm chitosan increased greatly the leaf nitrogen, phosphorus and potassium content compared to the control in the two seasons. At the same time, significant increase in leaf P content was found between 30 and 60 ppm concentrations compared to 90 ppm, in the two seasons, while, leaf potassium content was significantly increased with 30 ppm rather than 60 or 90 ppm in the second season.

         Spraying of spermidine  at 5, 10 and 20 ppm  enhanced markedly the leaf content from N, P and K compared to the control. In the meantime, significant increase in leaf N content was found with 5 ppm concentration compared to 20 ppm, in the first season. The results showed also that there were significant differences in leaf P content among the three concentrations. The application of VCL at 10, 15 and 20%  raised markedly the leaf content from N, P and K content over untreated trees. Besids, the results also showed that 15 and 20% significantly differed from the application of 10 %, in the second season. In the meantime, in the first season, significant differences were found in leaf P content among the three concentrations, while, a significant increase was found between 20% concentration compared to 10 and 15% for P content, in the second season and for leaf K content, in the first season. Significant increase in leaf K content was also found between 20 % compared to 10 % concentration, in the second season. Treating mango trees with potassium silicate, at 400, 500 and 600 ppm improved statistically the leaf composition from N, P and K contents over untreated trees. Significant differences, in leaf P content, were found among the three concentrations, while 600 ppm concentration caused a significant increase in leaf K content compared to 400 and 500 ppm, in the two seasons, in one side and compared to 400 ppm concentration for leaf N content, in the second season only, in the other side.

           Our obtained results are in the same line with the findings of many authors, they reported that the application of chitosan increased greatly the leaf composition from N, P and K in olive (Kasem and Fawzy, 2020) and mango (Saied and Radwan, 2017). Additionally, these results were previously explained by Balusamy et al. (2022), theyreported thatchitosan can reduce the free radicals, promotes the antioxidants, and plays as plant growth promoters, which enhances the absorption of minerals and water through  adjusting cell osmotic pressure. Polyamines can enhance the activity of metabolic processes and physiological activity (Youssef, 2007). Therefore, polyamines increased photosynthesis intensity and root discharge (Hosseini et al., 2018). Moreover, it involved N in their component, so, it acts as a source of N (Fereshteh et al. ( 2019) and Rezvanypour  et al. (2016). However, spermidine has the greatest effect on root length and root dry weight, and because P is absorbed more from the tip of the roots, spermidine treatment has the greatest effect on the amount of plant P.

            Abd El–Hamied (2018) found that VCL significantly raised the leaf mineral content of mango cv. Keitt. These results may be due to that foliar spray of VCL, which can increase salt tolerance by reducing the accumulation of Na+ in the tree (Siamak et al.,2017). Also significant increase in the growth occurred on VCL treated plants could be due to the proper ratio of macro and micronutrients in the VCL (Hatti et al., 2010) and its positive effect, which acts as plant tonic, contains elements, humic acid, fulvic acid, amino acids, vitamins, enzymes, microorganisms, actinomycetes and auxins and cytokines (Suthar , 2010). Spraying potassium silicate enhanced leaf N, P, and K of ‘Keitt’ mango trees, (Abd El-Rahman, 2015; Abdel Gawad, 2017). Besides, Dat et al. (2007) documented that  potassium silicate has a beneficial influence on on ‘Hindi’ mango by  enhancing the cell division, the biosynthesis of carbohydrates and plant pigments, and the resistance of the stress to biotic and a biotic stress.

Table (6): Effect of spraying chitosan, spermidine, and vermicomposting leachate and potassium silicate treatments on some leaf mineral compositions (N, P and K) in Keitt mango cultivar during 2020 and 2021 seasons

       Means followed by the same letter(s) within a separate column are not significantly different at 0.05 level of probability.