**4. The pineapple in Brazil**

The pineapple tree *Ananas comosus* (L.) Merril belongs to the Bromeliaceae family, subclass of subclass of Monocotyledonous and gender *Ananas*. It is a plant native to South America, covering latitude from 15° N to 30° S and longitude from 40° E to 60° W. About 50 genders and 2000 species of Bromeliaceae are known, some of them showing high ornamental value and others producing fibers excellent for cordage [33].

**3.3. Results**

204 Soil Fertility

ment (Table 6).

Coefficient Variation

[32].

\* Average values (n = 12)

**3.4. Conclusions**

**4. The pineapple in Brazil**

pared to trees not receiving K in these years.

**K2O Growing Season**

nual addition K to soil, with fruit size more affected by K.

The results showed the apple yield was increased by K fertilization in four of eight evaluat‐ ing growing seasons (Table 7), corroborating the results obtained in a long term experiments in south Brazil. The maximum increment in yield due to K fertilization ranged from 8.4 t ha-1 to 17.5 t ha-1, representing increases of 16,0% and 68,3% in fruit yield, respectively, as com‐

In the first and third year no effect of K fertilization on yield was detected, because of the high exchangeable K content in the soil in all orchards prior to establishment of the experi‐

Yield was more consistently increased by K fertilization after the 2002/2003 growing season, when exchangeable K contents were reduced in the plots without fertilization. The absence of response in the 2005/2006 growing season can be attributed to the increase in K levels of the plant, as a result of lower yields observed in the previous two growing seasons (Table 7).

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

Mean 50.2 56.5 40.6 44.3 42.5 33.8 37.5 51.4

**98/99 99/00 00/01 01/02 02/03 03/04 04/05 05/06 98-06**

 50.7\* 52.5 38.7 41.0 35.3 28.3 25.6 46.6 318.7 50.5 56.8 38.9 43.3 40.6 31.1 38.8 55.3 355.3 50.8 60.9 40.7 47.5 46.4 36.2 42.4 54.7 379.6 48.7 56 44.1 45.6 47.7 39.7 43.1 49.2 374.1

34.5 21.1 35.9 29.7 17.8 24.6 20.5 31.3

**Table 7.** Average annual and cumulative fruit yield (1998-2006) for 'Fugi', as affected by annual surface adition of K.

Yield size of apple were influencied, in a non interactive way, by K fertilization. Depending upon the growing season, yield and size of the fruit were often increased in response to an‐

The pineapple tree *Ananas comosus* (L.) Merril belongs to the Bromeliaceae family, subclass of subclass of Monocotyledonous and gender *Ananas*. It is a plant native to South America, According to [34], the fruit of the pineapple tree is composite or multiple types called syn‐ carp or sorosis formed by the coalescence of individual fruits, berry type, in a spiral on the central axis which is the continuation of the peduncle. The fruit is parthenocarpic, i.e., formed without the advent of fecundation. This fecundation may be possible but generally the varieties cultivated are self-sterile. According to [35], the skin of the fruit is composed of sepals and tissues of bracts and apices of the ovaries, while its edible portion consists mainly of the ovaries and bases of the sepals and bracts, as well as the cortex of the central axis.

The leaves of the pineapple tree, which can reach a maximum 70 to 80 per plant, are rigid and serous in the surface and protected by a layer of hair (trichomes) found in the lower sur‐ face, which reduces transpiration to a minimum [36]. The leaves are inserted in the stem and arranged in a rosette where older leaves are located on the outside of the plant and the new‐ est in the center [37]. The "D Leaves" are the newest among the adults and the most physio‐ logically active within all leaves, the reason why they are used in evaluations of nutritional status of the plant and in measures of growth [36].

The radicular system of a mature plant is of the fasciculated type and is located in the super‐ ficial part of soil surface. The majority of the roots are located in the first 15 to 20 cm of depth. The process of flowering begins with the reduction in vegetative growth velocity with a corresponding increase in collection of starch in leaves and stem [38].

The pineapple, native to Brazil, thrives under the Country´s ideal soil and climate condi‐ tions, where it is grown from North to South, and its economic importance is acknowledged everywhere.

Pearl is the major variety in Brazil while in the world the Smooth Cayenne variety is the most popular. Although having an acid taste, this variety boasts the characteristics required by the consumers. To please consumers' eyes and palate, pineapples must have yellow pulp and skin, cylindrical shape, small crown and a taste similar to the Pearl variety, in addition to normal packaging and labeling requirements.

Brazil is one of the world greatest growers of pineapple producing around 2.5 million tons in 2008 [39]. Despite the importance of potassium fertilization for this crop, there is a lack of information about the effects of different sources of K on fruit yield.

The pineapple tree is considered the worldwide third most cultivated fruit tree and exhibits a market which annually moves about US\$ 1 billion dollars, being cultivated in more than 50 countries [39]. The Philippines followed by Thailand are the world biggest producers of pineapple with an annual production of two million tons, next in 6th place Brazil reaches around 1.47 billion fruits per year and, in the sequence, India, Nigeria and México [40].

In Brazil the pineapple is traditionally cultivated under rainfed conditions, in sandy, acid and low-fertility soils, with limitations for Ca, Mg and K and unbalances on the ratios among those cations [41]. In real values potassium and nitrogen are the most ab‐ sorbed elements by the pineapple tree. The size and weight of the fruit are variables di‐ rectly related to nitrogen, while potassium is linked to the physical-chemical quality of the fruits [42,43,44,45].

of this element on the plant. Potassium sulphate is the most appropriate source, for being

Potassium Fertilization on Fruits Orchards: A Study Case from Brazil

http://dx.doi.org/10.5772/53210

207

The presence of chlorine affects the starch and sugar contents in the plant. High concentra‐ tions may prevent fructification and potassium absorption, reducing the size of the fruit, the sugar and starch contents, increasing the acidity, symptoms similar to K deficiency [54].

When evaluating different combinations of potassium sulphate and chloride, supplied in pits of basal leaves, at 30, 90, 180 and 270 days after planting at the dose of 8 g plant-1 K2O, [55] no differences were observed in the production and quality of the fruits when cultivat‐ ing Smooth Cayenne, although a trend of slight increase in acidity and decrease in total soluble solids/total titratable acidity ratio had occurred to the extent that the applications of sulphate were replaced by potassium chloride. In addition, no visible registered symptoms

In [56], the effect of fertilization (potassium sulphate, 0; 8 and 16 g plant-1 K2O) on the pro‐ duction and quality of the fruits from Smooth Cayenne cultivar, in Argissolo Vermelho dos Tabuleiros Costeiros de Pernambuco, containing 17 mg dm-3 K was evaluated. Significant ef‐ fects of K on the content of soluble solids were seen, which reached maximum values at the

When evaluating the effect of four doses of K (0, 413, 722 and 1.031 kg ha-1 K2O), applied in the form of potassium chloride, in low fertility soil from Minas Gerais, [57] observed better use of K by the plants in the presence of liming and that the doses of K2O which maximized the production were greater in more elevated doses of N (236 and 720 kg ha-1 K2O to 10 and 15 g plant-1 de N, respectively). The increase in doses of K increased the foliar content of K and reduced the Ca and Mg content. It also increased the content of total soluble solids and

Overall, the doses of K to maximize the quality attributes of the fruits are greater than those to maximize the production. In this context, [44] when evaluating the doses of K (0, 175, 350 and 700 kg ha-1 K2O) necessary to obtain maximum physical and quality yield of pineapple fruits Smooth Cayenne cv. observed that the doses of K positively influenced the size of the fruits and a total production in addition to increase the content of vitamin C, soluble solids and total acidity. However, the dose of K to maximize the size of the fruits (569 kg ha-1 K2O),

Due to a long cycle culture and high K demand throughout the cycle, the application of po‐ tassium fertilizers in the pineapple tree should be divided to meet the demands of the cul‐ ture, minimize losses, increase efficiency of fertilizations and improve fruit quality [43].

In Brazil, the main soil classes are Latosoil and Argisoil with elevated degree of intemperiza‐ tion and little presence of potassium minerals. In less intemperized soils, like Neosoils, Ver‐ tisoils, Luvisoils and Chernosoils, more rare in the Country, there are larger quantities of potassium minerals, like feldspates and mica, which may represent important sources of the nutrient [58]. Thus, soil contents maintenance appropriate to plants becomes extremely im‐

of foliar burning were registered by the use of KCl nor changes in fruit color.

fruit acidity, granting good balance in the SST/ATT, *ratio*.

portant in cultivation of the pineapple tree.

was higher than the one to maximize the production (498 kg ha-1 K2O).

less harmful to the crop.

dose of 15.6 g plant-1 K2O.

#### **4.1. Potassium fertilization in pineapple**

The nutrients required the most by the pineapple tree and which influence its growth are potassium and nitrogen [46]. Potassium is the nutrient which accumulates the most in the plant, markedly interferes in product quality and also in culture productivity; ni‐ trogen mostly influences the fruit mass. The pineapple tree is not very demanding in phosphorus and its importance to the plant is mainly in floral differentiation and fruit development phase [47]. In [48] it is mentioned that an increase of N reduces the acidi‐ ty of the fruits, but it can or cannot decrease soluble solids. According to [49,50], the extraction for macronutrients in decreasing order is expresser: K, N, Ca, Mg, S and P and for micronutrients: Mn, Fe, Zn, B, Cu, Mo.

Potassium is an important enzyme activator, responsible for opening and closing of stomata and carbohydrate transportation. It increases the content of soluble solids and acidity, im‐ proves the color and firmness of the skin and pulp and increases the mean weight and diam‐ eter of the fruit, and also decreases the emergence of internal darkening of the fruit [51].

According to [52] potassium fertilization can be supplied with potassium chloride, potassi‐ um sulphate, potassium and magnesium double sulphate and potassium nitrate, the two last ones being harder to find on the market and more expensive. The minimum guarantees and characteristics are presented in Table 8.


¹ Source: Instrução normativa nº 5 do Ministério da Agricultura, Pecuária e Abastecimento [53].

**Table 8.** Sources of potassium used in pineapple trees1.

The mostly used source by the producers is potassium chloride due to its low cost, but its composition has chloride which is a toxic element. The combination of chloride from the fer‐ tilizer with the one present in the irrigation water in the region, further increases the toxicity of this element on the plant. Potassium sulphate is the most appropriate source, for being less harmful to the crop.

sorbed elements by the pineapple tree. The size and weight of the fruit are variables di‐ rectly related to nitrogen, while potassium is linked to the physical-chemical quality of

The nutrients required the most by the pineapple tree and which influence its growth are potassium and nitrogen [46]. Potassium is the nutrient which accumulates the most in the plant, markedly interferes in product quality and also in culture productivity; ni‐ trogen mostly influences the fruit mass. The pineapple tree is not very demanding in phosphorus and its importance to the plant is mainly in floral differentiation and fruit development phase [47]. In [48] it is mentioned that an increase of N reduces the acidi‐ ty of the fruits, but it can or cannot decrease soluble solids. According to [49,50], the extraction for macronutrients in decreasing order is expresser: K, N, Ca, Mg, S and P

Potassium is an important enzyme activator, responsible for opening and closing of stomata and carbohydrate transportation. It increases the content of soluble solids and acidity, im‐ proves the color and firmness of the skin and pulp and increases the mean weight and diam‐ eter of the fruit, and also decreases the emergence of internal darkening of the fruit [51].

According to [52] potassium fertilization can be supplied with potassium chloride, potassi‐ um sulphate, potassium and magnesium double sulphate and potassium nitrate, the two last ones being harder to find on the market and more expensive. The minimum guarantees

**Source Minimum guarantees/characteristics** Potassium chloride KCl 58% K2O. Potassium in the form of chloride determined as K2O soluble in

Potassium sulphate K2SO4 48% K2O and 15% de S. Potassium in the form of sulphate, determined as K2O soluble in water. Potassium nitrate KNO3 44% K2O and 12% de N. Potassium determined as K2O soluble in water. Nitrogen in the nitric form.

20% K2O, 10% de Mg and 20% de S. Potassium and magnesium

determined as K2O and Mg soluble in water.

5 do Ministério da Agricultura, Pecuária e Abastecimento [53].

The mostly used source by the producers is potassium chloride due to its low cost, but its composition has chloride which is a toxic element. The combination of chloride from the fer‐ tilizer with the one present in the irrigation water in the region, further increases the toxicity

water.

the fruits [42,43,44,45].

206 Soil Fertility

**4.1. Potassium fertilization in pineapple**

and for micronutrients: Mn, Fe, Zn, B, Cu, Mo.

and characteristics are presented in Table 8.

Potassium and magnesium double sulphate

**Table 8.** Sources of potassium used in pineapple trees1.

Source: Instrução normativa nº

K2SO4 . 2MgSO4

¹

The presence of chlorine affects the starch and sugar contents in the plant. High concentra‐ tions may prevent fructification and potassium absorption, reducing the size of the fruit, the sugar and starch contents, increasing the acidity, symptoms similar to K deficiency [54].

When evaluating different combinations of potassium sulphate and chloride, supplied in pits of basal leaves, at 30, 90, 180 and 270 days after planting at the dose of 8 g plant-1 K2O, [55] no differences were observed in the production and quality of the fruits when cultivat‐ ing Smooth Cayenne, although a trend of slight increase in acidity and decrease in total soluble solids/total titratable acidity ratio had occurred to the extent that the applications of sulphate were replaced by potassium chloride. In addition, no visible registered symptoms of foliar burning were registered by the use of KCl nor changes in fruit color.

In [56], the effect of fertilization (potassium sulphate, 0; 8 and 16 g plant-1 K2O) on the pro‐ duction and quality of the fruits from Smooth Cayenne cultivar, in Argissolo Vermelho dos Tabuleiros Costeiros de Pernambuco, containing 17 mg dm-3 K was evaluated. Significant ef‐ fects of K on the content of soluble solids were seen, which reached maximum values at the dose of 15.6 g plant-1 K2O.

When evaluating the effect of four doses of K (0, 413, 722 and 1.031 kg ha-1 K2O), applied in the form of potassium chloride, in low fertility soil from Minas Gerais, [57] observed better use of K by the plants in the presence of liming and that the doses of K2O which maximized the production were greater in more elevated doses of N (236 and 720 kg ha-1 K2O to 10 and 15 g plant-1 de N, respectively). The increase in doses of K increased the foliar content of K and reduced the Ca and Mg content. It also increased the content of total soluble solids and fruit acidity, granting good balance in the SST/ATT, *ratio*.

Overall, the doses of K to maximize the quality attributes of the fruits are greater than those to maximize the production. In this context, [44] when evaluating the doses of K (0, 175, 350 and 700 kg ha-1 K2O) necessary to obtain maximum physical and quality yield of pineapple fruits Smooth Cayenne cv. observed that the doses of K positively influenced the size of the fruits and a total production in addition to increase the content of vitamin C, soluble solids and total acidity. However, the dose of K to maximize the size of the fruits (569 kg ha-1 K2O), was higher than the one to maximize the production (498 kg ha-1 K2O).

Due to a long cycle culture and high K demand throughout the cycle, the application of po‐ tassium fertilizers in the pineapple tree should be divided to meet the demands of the cul‐ ture, minimize losses, increase efficiency of fertilizations and improve fruit quality [43].

In Brazil, the main soil classes are Latosoil and Argisoil with elevated degree of intemperiza‐ tion and little presence of potassium minerals. In less intemperized soils, like Neosoils, Ver‐ tisoils, Luvisoils and Chernosoils, more rare in the Country, there are larger quantities of potassium minerals, like feldspates and mica, which may represent important sources of the nutrient [58]. Thus, soil contents maintenance appropriate to plants becomes extremely im‐ portant in cultivation of the pineapple tree.
