**4.2. Sampling and chemical analysis of the soil**

Some technical criteria should be adopted in soil sampling, since failure in the collection of soil samples generate errors that cannot be corrected later by soil analysis. All care should be taken in order to the samples being representative of the areas to be cultivated.

The sample collection should be performed before plantation, with enough time for the cor‐ rective to have time to react and to perform the fertilization step. The area to be sampled should be divided in homogeneous plots. For this division, observe the topography, vegeta‐ ble covering, area history, drainage, soil texture, soil color and further related factors.

At the samples withdrawal the arable layer, which normally is more intensely changed by plowing, harrowing, correctives, fertilizers and culture residues, is considered. Therefore, sampling should be performed in this layer from 0 to 20 cm depth. For the analysis of sub superficial acidity and availability of sulfur the depth from 20 to 40 cm should be collected.

For larger representativeness, 15 to 20 single samples should be collected, using an instru‐ ment which provides equal volume between collections, at randomly distributed points in each area; the set of single samples will constitute the composite sample (500g homogenized fraction).

**Figure 6.** Overview of a pineapple plant with indication of the leaf to be sampled for chemical analysis (Leaf "D").

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209

**Figure 7.** Morphological representation of pineapple tree leaves. Leaf A, the eldest, to F, the youngest. (Adapted from [60]).

As an evaluation parameter for the nutritional state, there are nutrient levels in leaves com‐ pared to optimal values, such as in sufficiency ranges or critical levels, presented in tables. Thus, when a nutrient concentration is different from the values presented in those tables, it is suggested that it will limit the plant growth, or productivity and even quality of the fruit.

According to the literature, there are indications of contents of nutrients considered appro‐ priate for the pineapple tree (Table 9). It is observed that there are variations among the nu‐ trients compared to the whole leaf, chlorophylled and achlorophylled portion. This fact

shows the importance of standards when collecting leaf samples.

Photo: REIS, L. L.

The composite sample from each area should be forwarded to a lab for soil chemical analy‐ sis for fertility purposes that present performance control of its results by IAC, easily identi‐ fied by the seal. The requested analyses should be the basic (pH, MO, P, H+Al, K, Ca and Mg) and micronutrients (B, Cu, Fe, Mn and Zn) ones. Optionally, the analyses of Al, SO4 2 and texture can be requested, as indicated.

## **4.3. Evaluation of nutritional availability**

Foliar diagnosis was performed for plants status nutritional evaluation. Foliar analysis allow monitoring the of fertilizers used, however, is necessary caution for sample collection, work‐ ing within sampling standards and criteria.

#### **4.4. Foliar diagnosis**

In leaf sampling, it is important to establish criteria to define the plots, grouping plots with similar characteristics regarding cultivated variety, age, phenology, handling, productivity and which ones belong to areas with homogeneous soils.

For the pineapple tree it is recommended to collect the Leaf "D" (Figure 6), considered meta‐ bolically more active, which is the last well-developed leaf, generally the longest one, form‐ ing, in general, a 450 angle relative to the soil (Figure 7). The sample collection should be performed by the period of floral induction [59]. However, the sampling time indicated for the pineapple tree does not allow corrections in the current crop. The suggestion is to collect at least 25 leaves of different plants, from each uniform plot, randomly taken, considering one leaf per plant [17].

**4.2. Sampling and chemical analysis of the soil**

and texture can be requested, as indicated.

**4.3. Evaluation of nutritional availability**

ing within sampling standards and criteria.

and which ones belong to areas with homogeneous soils.

**4.4. Foliar diagnosis**

ing, in general, a 450

one leaf per plant [17].

fraction).

208 Soil Fertility

Some technical criteria should be adopted in soil sampling, since failure in the collection of soil samples generate errors that cannot be corrected later by soil analysis. All care should be

The sample collection should be performed before plantation, with enough time for the cor‐ rective to have time to react and to perform the fertilization step. The area to be sampled should be divided in homogeneous plots. For this division, observe the topography, vegeta‐

At the samples withdrawal the arable layer, which normally is more intensely changed by plowing, harrowing, correctives, fertilizers and culture residues, is considered. Therefore, sampling should be performed in this layer from 0 to 20 cm depth. For the analysis of sub superficial acidity and availability of sulfur the depth from 20 to 40 cm should be collected.

For larger representativeness, 15 to 20 single samples should be collected, using an instru‐ ment which provides equal volume between collections, at randomly distributed points in each area; the set of single samples will constitute the composite sample (500g homogenized

The composite sample from each area should be forwarded to a lab for soil chemical analy‐ sis for fertility purposes that present performance control of its results by IAC, easily identi‐ fied by the seal. The requested analyses should be the basic (pH, MO, P, H+Al, K, Ca and Mg) and micronutrients (B, Cu, Fe, Mn and Zn) ones. Optionally, the analyses of Al, SO4

Foliar diagnosis was performed for plants status nutritional evaluation. Foliar analysis allow monitoring the of fertilizers used, however, is necessary caution for sample collection, work‐

In leaf sampling, it is important to establish criteria to define the plots, grouping plots with similar characteristics regarding cultivated variety, age, phenology, handling, productivity

For the pineapple tree it is recommended to collect the Leaf "D" (Figure 6), considered meta‐ bolically more active, which is the last well-developed leaf, generally the longest one, form‐

performed by the period of floral induction [59]. However, the sampling time indicated for the pineapple tree does not allow corrections in the current crop. The suggestion is to collect at least 25 leaves of different plants, from each uniform plot, randomly taken, considering

angle relative to the soil (Figure 7). The sample collection should be

2-

ble covering, area history, drainage, soil texture, soil color and further related factors.

taken in order to the samples being representative of the areas to be cultivated.

**Figure 6.** Overview of a pineapple plant with indication of the leaf to be sampled for chemical analysis (Leaf "D"). Photo: REIS, L. L.

**Figure 7.** Morphological representation of pineapple tree leaves. Leaf A, the eldest, to F, the youngest. (Adapted from [60]).

As an evaluation parameter for the nutritional state, there are nutrient levels in leaves com‐ pared to optimal values, such as in sufficiency ranges or critical levels, presented in tables. Thus, when a nutrient concentration is different from the values presented in those tables, it is suggested that it will limit the plant growth, or productivity and even quality of the fruit.

According to the literature, there are indications of contents of nutrients considered appro‐ priate for the pineapple tree (Table 9). It is observed that there are variations among the nu‐ trients compared to the whole leaf, chlorophylled and achlorophylled portion. This fact shows the importance of standards when collecting leaf samples.


**4.5. Visual diagnosis**

acidity and no aroma.

mercial value.

likelihood of increasing the production costs.

bed hereafter, are reported according to [71].

The information on visual symptoms of nutritional deficiencies of the pineapple tree, descri‐

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211

Potassium deficiency (Figure 8) is characterized by green to dark green foliage, more pro‐ nounced with nitrogenized fertilization. The leaves show small yellow dots that grow, mul‐ tiply and may concentrate on the limb margins. Dryness on the apical extremity also occurs. The plant presents erect port and slightly resistant peduncle. The fruit is small, with low

**Figure 8.** Symptoms of potassium deficiency in pineapple tree leaves. Photo: REINHARDT, D.H.

Potassium deficiency occurs frequently, except in plantings installed in soils rich in this nu‐ trient. It is favored by unbalanced nitrogen rich fertilization, by strong solar radiation, by intense lixiviation and by soils with increased pH and rich in Ca and Mg. According to [72] potassium fertilization intensifies the color of the skin of ripe fruits, changes the color of the pulp from yellow-straw to golden yellow, increases the content of total soluble solids and acidity and improves the organoleptic characteristics of the fruits, providing a better com‐

In [47], fruits with lower levels of sugar, less acids, slightly colored, weaker aroma and little resistant peduncle were observed under potassium deficiency, turning those fruits more susceptible to tipping and sun burning. According to [73], it was described that the visual symptoms of K deficiency are characterized by presenting the apex of the older leaves

As general information, it can be stated that the pineapple tree fertilization should be per‐ formed in the vegetative phase of the plant cycle, period in which there is a more efficient use of the nutrients applied. Anyway, caution should be exercised regarding the decision making on applying fertilizers in the reproductive phase of the plant cycle, considering the

browned and necrotic. Fruits deficient in K presented a pulp with interior darkening.

Source: Adapted from [61]; A and B -[62]; C – [63,64]; D\*-[65,66], Cultivation with full fertilization; E\*\*- [65,66], Culti‐ vation with nutrient deficiency; F\*\*\* -[67], Contents of nutrients in foliar dry matter from pineapple tree seedling at nine months after seed-plotting of sections from the stem; G-[68]; H- [69].

**Table 9.** Nutrient contents and ranges observed in foliar dry matter from the pineapple tree in different trials.

DRIS(1 is an alternative technique to evaluate the nutritional state. The critical levels of N, P, K, Ca and Mg were estimated by [70] from the DRIS rules for the "Smooth Cayenne" pine‐ apple tree, in the Bauru – SP region: N (12.0 +/- 0.3(2)), P (0.92+/- 0.02), K (21.4+/- 0.6), Ca (4.0+/- 0.1), Mg (2.8 +/- 0.1), where (2) is the confidence interval (95% CI) for foliar critical levels estimated by means of a multiple regression between the DRIS indexes and the levels of macronutrients in the leaves.

<sup>1</sup> Integrated System of Diagnosis and Recommendations

## **4.5. Visual diagnosis**

**Authors**

**----------------------------------------------g kg-1--------------------------------------------------------------**

**---------------------------------------------mg kg-1----------------------------------------------------------**

**Productivity (fruits ha-1 x 1000)** 40 20 - - - - - - Part of the plant analyzed

**Portion**

**Achlorophylled Portion**

Fe 73.0 65.0 77.0 - - 118.0 100.0-200.0 80.0-150.0 Mn 149.0 132.0 67.4 - - 127.0 50.0-200.0 150.0-400.0 Zn 13.6 14.0 14.3 - - 12.5 5.0-15.0 15.0-70.0 Cu - - 4.5 - - 4.5 5.0-10.0 10.0-50.0

B - - 26.0 18.0-30.0 5.5-8.5 22.0 20.0-40.0 -

**-----------------------------Whole leaf'-------------------------- Chlorophylled**

**Table 9.** Nutrient contents and ranges observed in foliar dry matter from the pineapple tree in different trials.

nine months after seed-plotting of sections from the stem; G-[68]; H- [69].

of macronutrients in the leaves.

1 Integrated System of Diagnosis and Recommendations

Source: Adapted from [61]; A and B -[62]; C – [63,64]; D\*-[65,66], Cultivation with full fertilization; E\*\*- [65,66], Culti‐ vation with nutrient deficiency; F\*\*\* -[67], Contents of nutrients in foliar dry matter from pineapple tree seedling at

DRIS(1 is an alternative technique to evaluate the nutritional state. The critical levels of N, P, K, Ca and Mg were estimated by [70] from the DRIS rules for the "Smooth Cayenne" pine‐ apple tree, in the Bauru – SP region: N (12.0 +/- 0.3(2)), P (0.92+/- 0.02), K (21.4+/- 0.6), Ca (4.0+/- 0.1), Mg (2.8 +/- 0.1), where (2) is the confidence interval (95% CI) for foliar critical levels estimated by means of a multiple regression between the DRIS indexes and the levels

**A B C D\* E\*\* F\*\*\* G H**

N 10.3 8.8 16.3 13.0-15.0 6.6-9.7 10.9 15.0-17.0 15.0-25.0 P 1.4 1.5 2.1 1.0-1.4 0.3-13.8 2.0 0.8-1.2 1.4-3.5 K 25.0 22.0 20.0 20.0-24.0 3.2-13.8 24.0 22.0-30.0 43.0-65.0 Ca 3.4 3.2 3.9 4.3-7.6 0.9-2.3 6.5 8.0-12.0 2.2-4.0 Mg 3.5 3.1 2.4 2.1-3.6 0.5-1.3 2.2 3.0-4.0 4.1-5.7 S 0.6 0.7 1.3 1.4-1.8 0.4-1.2 1.6 - -

**Nutrie nts**

210 Soil Fertility

The information on visual symptoms of nutritional deficiencies of the pineapple tree, descri‐ bed hereafter, are reported according to [71].

Potassium deficiency (Figure 8) is characterized by green to dark green foliage, more pro‐ nounced with nitrogenized fertilization. The leaves show small yellow dots that grow, mul‐ tiply and may concentrate on the limb margins. Dryness on the apical extremity also occurs. The plant presents erect port and slightly resistant peduncle. The fruit is small, with low acidity and no aroma.

**Figure 8.** Symptoms of potassium deficiency in pineapple tree leaves. Photo: REINHARDT, D.H.

Potassium deficiency occurs frequently, except in plantings installed in soils rich in this nu‐ trient. It is favored by unbalanced nitrogen rich fertilization, by strong solar radiation, by intense lixiviation and by soils with increased pH and rich in Ca and Mg. According to [72] potassium fertilization intensifies the color of the skin of ripe fruits, changes the color of the pulp from yellow-straw to golden yellow, increases the content of total soluble solids and acidity and improves the organoleptic characteristics of the fruits, providing a better com‐ mercial value.

In [47], fruits with lower levels of sugar, less acids, slightly colored, weaker aroma and little resistant peduncle were observed under potassium deficiency, turning those fruits more susceptible to tipping and sun burning. According to [73], it was described that the visual symptoms of K deficiency are characterized by presenting the apex of the older leaves browned and necrotic. Fruits deficient in K presented a pulp with interior darkening.

As general information, it can be stated that the pineapple tree fertilization should be per‐ formed in the vegetative phase of the plant cycle, period in which there is a more efficient use of the nutrients applied. Anyway, caution should be exercised regarding the decision making on applying fertilizers in the reproductive phase of the plant cycle, considering the likelihood of increasing the production costs.

### **4.6. Effect of potassium fertilizer on pineapple**

Potassium is the nutrient required in the largest amount by the pineapple tree and its lack represents not only the decrease in plant growth and production, but also affects the quality of the fruits. Facing the importance of this nutrient for the culture, a research was performed where the main focus was to exploit the effects of potassium fertilization in aspects concern‐ ing the production and quality of the fruits.

**pH MO P K Ca Mg**

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5.0 9.0 5.0 1.0 9.0 3.0

**S H+Al Al SB CTC V**

4.0 20.0 3.0 12.6 34.8 36.0

**--------------------------------DTPA----------------------------- Warm water**

**(mg dm-3) -----------------------------mmolc dm-3------------------------- %**

**Cu Fe Mn Zn B**

0.4 21.0 46.0 0.8 0.2

**Table 10.** Chemical analysis of the soil in layer from 0 to 20cm. Performed by the Instituto Brasileiro de Análises –

For the installation of the experiment, seedlings of the "Pearl" pineapple tree, from the own University matrix mill located in the production sector. In soil preparation, liming was performed to increase the saturation by bases to 50% and the magnesium content to a minimum of 5 mmolc dm-3. The experiment was installed in April 2007, with 0.80 X 0.30 m spacing with a density of 41,666.66 plants ha-1, conducted in single lines. The fertiliza‐ tion in the planting furrow with 140 kg ha-1 P2O5 (320 kg ha-1 triple superphosphate) and top-dressing fertilization performed six times during the performance of the experiment with 222.22 Kg ha-1 urea (100 kg ha-1 N), in each fertilization, according to soil analysis (Table 11). For the treatments constitution fertilization, the following doses of potassium (K2O) were used: 0, 200, 400, 600, 800 kg ha-1, applied in 4 subdivisions, in June and De‐

The control of weeds, plagues and diseases were made during the whole period of the ex‐ periment, with herbicide Glyphosate (1 L ha-1), associated to mechanical methods; applica‐ tion of Imidacloprid insecticide 700 WG (30g 100 L H2O) and Tiametoxam 250 WG (300g 100 L H2O); fungicide Tebuconazole 200 EC (1L ha-1), respectively. The phytosanitary control was performed specifically to preclude problems related to diseases that enable the bad de‐ velopment of the culture. Floral induction was performed at 13 months of age, period in which the plant obtained enough size and age to respond to respond to floral differentiation stimulation. The product applied was Ethrel 720 (720 g etephon L-1), at the dose of 1.0 L ha-1,

The experimental design used was random blocks with four repetitions and 5 treatments, with experimental division composed by 7 plants, 5 central plants composing the useful por‐

being performed late in the afternoon to improve the efficiency of the product.

Source: Instituto Brasileiro de Análises – (IBRA AgriSciences). Campinas, SP, Brazil – 2009.

(IBRA AgriSciences). UEMS. Cassilândia, MS, Brazil. 2009.

cember 2007; March and June 2008.

tion. The treatments employed are in Table 11.

**CaCl2 g dm-3 mg dm-3 -----------------mmolc dm-3-------------------**

#### **4.7. Methodology**

The experiment was conducted in the period from April 2007 to November 2008, in the sec‐ tor of agricultural production in the State University of Mato Grosso do Sul, located in Cas‐ silândia, MS, with approximately 471m altitude, 19° 05' S latitude and 51° 56' W longitude. The climate of the region, according to the classification of [74] is considered rainy tropical (Aw), with a rainy summer and dry winter. Considering the tropical climate in the city of Cassilândia which holds minimal temperatures of 11.19 °C to 22.66 °C and maximum tem‐ peratures of 28.35 °C to 36.16 °C with annual precipitation of 2000 mm.

The monthly variations of temperature and precipitation occurring during the conduction of the experiment are represented in Figure 9.

For its execution, the experiment was installed in a medium texture soil, with chemical com‐ position during the implantation period of implantation and conduction of the experiment as presented in Table 10.

**Figure 9.** Maximum and minimum temperatures (A) and monthly precipitation (B), during the period of conduction of the experiment. Data provided by Agrometeorological Station from INPE/CPTEC (Instituto Nacional de Pesquisas Espa‐ ciais/Centro de Previsão de tempo e Estudos Climáticos).UEMS. Cassilândia, MS, Brazil. 2009.


**4.6. Effect of potassium fertilizer on pineapple**

ing the production and quality of the fruits.

the experiment are represented in Figure 9.

as presented in Table 10.

**4.7. Methodology**

212 Soil Fertility

Potassium is the nutrient required in the largest amount by the pineapple tree and its lack represents not only the decrease in plant growth and production, but also affects the quality of the fruits. Facing the importance of this nutrient for the culture, a research was performed where the main focus was to exploit the effects of potassium fertilization in aspects concern‐

The experiment was conducted in the period from April 2007 to November 2008, in the sec‐ tor of agricultural production in the State University of Mato Grosso do Sul, located in Cas‐ silândia, MS, with approximately 471m altitude, 19° 05' S latitude and 51° 56' W longitude. The climate of the region, according to the classification of [74] is considered rainy tropical (Aw), with a rainy summer and dry winter. Considering the tropical climate in the city of Cassilândia which holds minimal temperatures of 11.19 °C to 22.66 °C and maximum tem‐

The monthly variations of temperature and precipitation occurring during the conduction of

For its execution, the experiment was installed in a medium texture soil, with chemical com‐ position during the implantation period of implantation and conduction of the experiment

**Figure 9.** Maximum and minimum temperatures (A) and monthly precipitation (B), during the period of conduction of the experiment. Data provided by Agrometeorological Station from INPE/CPTEC (Instituto Nacional de Pesquisas Espa‐

ciais/Centro de Previsão de tempo e Estudos Climáticos).UEMS. Cassilândia, MS, Brazil. 2009.

peratures of 28.35 °C to 36.16 °C with annual precipitation of 2000 mm.

**Table 10.** Chemical analysis of the soil in layer from 0 to 20cm. Performed by the Instituto Brasileiro de Análises – (IBRA AgriSciences). UEMS. Cassilândia, MS, Brazil. 2009.

For the installation of the experiment, seedlings of the "Pearl" pineapple tree, from the own University matrix mill located in the production sector. In soil preparation, liming was performed to increase the saturation by bases to 50% and the magnesium content to a minimum of 5 mmolc dm-3. The experiment was installed in April 2007, with 0.80 X 0.30 m spacing with a density of 41,666.66 plants ha-1, conducted in single lines. The fertiliza‐ tion in the planting furrow with 140 kg ha-1 P2O5 (320 kg ha-1 triple superphosphate) and top-dressing fertilization performed six times during the performance of the experiment with 222.22 Kg ha-1 urea (100 kg ha-1 N), in each fertilization, according to soil analysis (Table 11). For the treatments constitution fertilization, the following doses of potassium (K2O) were used: 0, 200, 400, 600, 800 kg ha-1, applied in 4 subdivisions, in June and De‐ cember 2007; March and June 2008.

The control of weeds, plagues and diseases were made during the whole period of the ex‐ periment, with herbicide Glyphosate (1 L ha-1), associated to mechanical methods; applica‐ tion of Imidacloprid insecticide 700 WG (30g 100 L H2O) and Tiametoxam 250 WG (300g 100 L H2O); fungicide Tebuconazole 200 EC (1L ha-1), respectively. The phytosanitary control was performed specifically to preclude problems related to diseases that enable the bad de‐ velopment of the culture. Floral induction was performed at 13 months of age, period in which the plant obtained enough size and age to respond to respond to floral differentiation stimulation. The product applied was Ethrel 720 (720 g etephon L-1), at the dose of 1.0 L ha-1, being performed late in the afternoon to improve the efficiency of the product.

The experimental design used was random blocks with four repetitions and 5 treatments, with experimental division composed by 7 plants, 5 central plants composing the useful por‐ tion. The treatments employed are in Table 11.


region of Bauru, in Argisoil with 0.7mmolc dm-3 K available, the productivity of the Smooth Cayenne cultivar increased 9.2 t ha-1 in response to the application of KCl and 15 t ha-1 with the use of potassium sulphate, increases of 18% and 29% related to the control without K applica‐ tion were found, respectively [70]. According to [43, 76], the division of potassium doses in 4 applications during the culture cycle is efficient, regarding the maintenance of fruit quality, and mainly minimizes the losses by lixiviation, increasing the efficiency of the fertilization.

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In this experiment the quality of the fruits was evaluated from chemical attributes, soluble

The content of soluble solids estimates the concentration of sugars, which, in most cases, de‐ termine the flavor of the fruit. The measurement of soluble solids is used as an indicator of the maturation and quality of the fruits. The fruits destined to *in natura* consumption should have a content of soluble solids higher than 12 ºBrix [77]. In this experiment the influence of potassium on the soluble solids content, which values ranged from 13 to 13.50 ºBrix, was not verified. According to observations performed by [78], the soluble solids contents, found in fruits of Smooth Cayenne fruit tree, which varied from 13.74 to 15.50 ºBrix, were also not directly influenced by K2O treatments. In a trial performed by [79], the positive effect of po‐ tassium fertilization on total soluble solids contents (TSS) was observed, which the applica‐

For the characteristic titratable acidity, the data adjusted to a linear ascending equation relat‐ ed to the dose of K2O. The maximum value of 1.01 mL 100g citric acid-1 was found, when associated to the application of 800 Kg ha-1 K2O (Figure 11). Observations made by [80] indi‐ cate that the pineapple fruits subjected to low temperatures, both before and after harvest‐ ing, increase the incidence and severity of internal darkening of the fruit (*blacheart* or *internal browing*). It has also been observed that the affected fruits are mildly acid and have low lev‐

**Figure 11.** Effect of potassium doses in total titratable acidity of cultivar 'Pearl' pineapple tree fruits. UEMS. Cassilân‐

**2.** Potassium fertilization and fruit quality

solids, titratable acidity, *ratio* (SS/AT) and ascorbic acid.

tion of 490 kg ha-1 K2O increased the TSS in about 6%.

els of ascorbic acid.

dia, MS, Brazil. 2009.

\*Potassium chloride (60% K2O), used in the application of treatments.

**Table 11.** Treatments used in the experiment with potassium fertilization. UEMS. Cassilândia, MS, Brazil. 2009.

#### **4.8. Results**

**a.** Potassium fertilization and productivity

The results obtained evidenced that the productivity of fruits was influenced by potassium fertilization applied in top-dressing. The regression analysis evidenced a quadratic behavior whose estimated value was 409.38 Kg ha-1 K2O associated to a productivity of 52,507.30 Kg ha-1 (Figure 10). The quadratic response of the pineapple tree to the KCl doses (Figure 10), may be associated to the depressive effect of the chloride ion, mainly at the higher doses, because according to [75], it is a plant sensitive to chloride toxicity.

**Figure 10.** Effect of potassium doses in the productivity of the cultivar Pearl pineapple plant. UEMS. Cassilândia, MS, Brazil. 2009.

According to [42], a positive and significant association was verified within the production of fruits of the "Pearl" pineapple tree. The application of potassium promoted a productivi‐ ty of 79 t ha-1 of fruits with the estimated dose of 22 g K2O plant-1.

The potassium content available in the soil and the source used has a promising effect on the way that the pineapple is responsible to potassium fertilization. In an essay performed in the region of Bauru, in Argisoil with 0.7mmolc dm-3 K available, the productivity of the Smooth Cayenne cultivar increased 9.2 t ha-1 in response to the application of KCl and 15 t ha-1 with the use of potassium sulphate, increases of 18% and 29% related to the control without K applica‐ tion were found, respectively [70]. According to [43, 76], the division of potassium doses in 4 applications during the culture cycle is efficient, regarding the maintenance of fruit quality, and mainly minimizes the losses by lixiviation, increasing the efficiency of the fertilization.

**2.** Potassium fertilization and fruit quality

**Treatments K2O Rates KCl Rates \***

**Table 11.** Treatments used in the experiment with potassium fertilization. UEMS. Cassilândia, MS, Brazil. 2009.

The results obtained evidenced that the productivity of fruits was influenced by potassium fertilization applied in top-dressing. The regression analysis evidenced a quadratic behavior whose estimated value was 409.38 Kg ha-1 K2O associated to a productivity of 52,507.30 Kg ha-1 (Figure 10). The quadratic response of the pineapple tree to the KCl doses (Figure 10), may be associated to the depressive effect of the chloride ion, mainly at the higher doses,

**Figure 10.** Effect of potassium doses in the productivity of the cultivar Pearl pineapple plant. UEMS. Cassilândia, MS,

According to [42], a positive and significant association was verified within the production of fruits of the "Pearl" pineapple tree. The application of potassium promoted a productivi‐

The potassium content available in the soil and the source used has a promising effect on the way that the pineapple is responsible to potassium fertilization. In an essay performed in the

1 0.0 0.0 200.0 333.3 400.0 666.6 600.0 1000.0 800.0 1333.3

because according to [75], it is a plant sensitive to chloride toxicity.

ty of 79 t ha-1 of fruits with the estimated dose of 22 g K2O plant-1.

\*Potassium chloride (60% K2O), used in the application of treatments.

**a.** Potassium fertilization and productivity

**4.8. Results**

214 Soil Fertility

Brazil. 2009.

**--------------------------------Kg ha-1---------------------------**

In this experiment the quality of the fruits was evaluated from chemical attributes, soluble solids, titratable acidity, *ratio* (SS/AT) and ascorbic acid.

The content of soluble solids estimates the concentration of sugars, which, in most cases, de‐ termine the flavor of the fruit. The measurement of soluble solids is used as an indicator of the maturation and quality of the fruits. The fruits destined to *in natura* consumption should have a content of soluble solids higher than 12 ºBrix [77]. In this experiment the influence of potassium on the soluble solids content, which values ranged from 13 to 13.50 ºBrix, was not verified. According to observations performed by [78], the soluble solids contents, found in fruits of Smooth Cayenne fruit tree, which varied from 13.74 to 15.50 ºBrix, were also not directly influenced by K2O treatments. In a trial performed by [79], the positive effect of po‐ tassium fertilization on total soluble solids contents (TSS) was observed, which the applica‐ tion of 490 kg ha-1 K2O increased the TSS in about 6%.

For the characteristic titratable acidity, the data adjusted to a linear ascending equation relat‐ ed to the dose of K2O. The maximum value of 1.01 mL 100g citric acid-1 was found, when associated to the application of 800 Kg ha-1 K2O (Figure 11). Observations made by [80] indi‐ cate that the pineapple fruits subjected to low temperatures, both before and after harvest‐ ing, increase the incidence and severity of internal darkening of the fruit (*blacheart* or *internal browing*). It has also been observed that the affected fruits are mildly acid and have low lev‐ els of ascorbic acid.

**Figure 11.** Effect of potassium doses in total titratable acidity of cultivar 'Pearl' pineapple tree fruits. UEMS. Cassilân‐ dia, MS, Brazil. 2009.

Regarding the *ratio,* the increment in K2O doses verified that with the dose increase there was a decrease in the index. The values found were 17.78, with no application of K2O and 12.78, when the maximum dose was used (800 Kg ha-1). The reduction in the index coupled to potassium dose increments was attributed to a higher increase in acidity related to solu‐ ble solids content (Figure 12). This observation corroborates [79], who verified that in Smooth Cayenne pineapple tree, the potassium fertilization acted in two ways in the forma‐ tion of the *ratio*, as a function of the type of potassium source used. Thus, the increment in titratable acidity was bigger only when KCl was employed as a source of K than the one ob‐ served with K2SO4 application. Thus, the applications over 400 Kg há-1 K2O under the form of KCl, implicated in the production of fruits with a *ratio* below 20. When potassium sul‐ phate was employed as K source, it was possible to employ higher K doses, without the *ratio* being lower than 25.

Thereby the efficiency in the use of K is directly related to the direct effects on the amount and quality of fruits, being the handling of the fertilization one of the factors that strongly influences the sustainability in the production of fruit trees. In addition to the choice of K source, strategies should be sought for the handling of solo-plant systems that minimize the loss of this nutrient, taking the example of dose division, minimizing losses by lixiviation.

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[1] Leonel, S. A figueira. Revista Brasileira de Fruticultura, Jaboticabal/SP, v. 30, set.

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**Author details**

**References**

2008.

Cargil, 1986. p.115-129.

n.125, p.12-31, 1985.

NEP, 1999. p.69-85.

Sarita Leonel1\* and Luis Lessi dos Reis2\*

\*Address all correspondence to: sarinel@fca.unesp.br

\*Address all correspondence to: lessireis@fca.unesp.br

2 UNESP (São Paulo State University), Botucatu-SP, Brazil

1 UNESP. FCA, Department of plant production, Botucatu, SP, Brazil

ção, Instituto Agronômico de Campinas, 1996. p.139-140.

**Figure 12.** Effect of potassium doses in the *ratio* of cultivar 'Pearl' fruits of pineapple tree. UEMS. Cassilândia, MS, Brazil. 2009.

#### **4.9. Conclusions**

With the results obtained, the potassium fertilization coupled with the division of doses met the requirement of the plants, according to its development cycle, mainly at the association of K2O to the dose of 410 Kg ha-1.
