**2. The fig tree**

The fig tree (*Ficus carica*, L.) originated from Asia Minor and Syria, in the Mediterranean re‐ gion, and was first cultured and selected by Arabs and Jews in Southwest Asia. It is one of the oldest plants cultivated in the world – since prehistoric times – and is considered by an‐ cient people as a symbol of honor and fertility. According to botanists from the American University Harvard, Middle Eastern fig trees were the first species cultivated by humans, 11,400 years ago. Researchers have found the remains of small figs and dry seeds buried at a village in the Jordan Valley located to the north of Jericho. The fruits were well conserved, which indicates they were dried for consumption [1].

© 2012 Leonel and dos Reis; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Leonel and dos Reis; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The fig is one of the most popular food that has been sustaining humanity since the begin‐ ning of History. The fruit was used to feed advanced Olympic athletes and was offered to the winner as the first Olympic medal. The tree was described in many passages from the Bible as sacred and respected by man. During the period of the great discoveries, the fig was disseminated to the Americas. In Brazil, the fig tree was probably introduced by the first col‐ onizing expedition in 1532 in São Paulo State.

Although the nutritional demands of the fig tree are of fairly knowledge, its measurement involves components of a very complex range, since the nutrient demands are closely relat‐ ed to the aspects of the species' physiology. During reproductive phase, the nutritional re‐ quirements have a component which is easily measurable and highly important in the evaluation of nutritional demands, the export of nutrients within fruit crops. However, dur‐ ing plant formation phase, the nutritional demands become difficult to determine since those are only for the growth and establishment of the plant, as well as the analyses of de‐ velopment the plants are rarely done in this period. In this phase excessive fertilization is performed according to visual diagnosis done by the producer, which is not uncommon.

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According to [3], the knowledge of any needs or excesses of chemical elements responsible for the metabolism of plants and, due to the vegetation and productivity of fruit trees, it con‐ stitutes a necessary and indispensable step for corrective measures, since the fertilizing rec‐ ommendations consist in the employment of fertilizer amounts, aiming to correct the

The fertilizing recommendations during the formation period of the fig trees had been advo‐ cated exclusively from interpretations of soil analysis. In case of planting fertilizations, the recommendations are made by subjective criteria, not taking into consideration the content in the soil [4]. However, according to [3,5], soil analyses may be used to follow up the fertili‐ ty of the soil and fertilizing recommendations during the development of the plants, because when used concomitantly with diagnosis methods may yield better results. The nutritional state of the plant can reveal the availability of nutrients of the soil and the ability the plant has to absorb them. Yet, fertilizing recommendations based on nutrient demands for fruit production, growth of branches, trunk and roots, during the phase of plant formation, can‐ not be considered a practice sufficiently broad, since such requirements are hard to measure. According to [6,7], the nutritional demands are better evaluated for plants at full produc‐ tion, where the crops of unripe and ripe fruits constitute the main sources of nutrient ex‐

Due to scarce information on fertilization and nutrition of the fig tree, coupled to the evalua‐ tion of its effects on the nutritional state, a research was conducted using the levels of potas‐

The experiment was carried through in field conditions at the Orchard of Experimental Farm, of São Paulo State University, Faculty of Agronomic Sciences, Campus of Botucatu,

51' 55" South Latitude, 480

altitude of 830 meters. The predominant climatic type at the location, according to [9,10], based on the KOEPPEN international System, is included in the Cfb, namely the temperate

26' 22" Western Longitude, with

**2.2. Nutritional diagnosis and fertilization recommendations**

element or limiting factor detected by the diagnosis.

**2.3. Effect of potassium fertilizer on the fig tree**

sium fertilization, during the period of plant formation [8].

tracting sources.

**2.4. Methodology**

São Paulo, Brazil, located at 220

In Brazil, economic exploration of the fig tree only started from 1910, when it was first com‐ mercially cultivated in Valinhos region, São Paulo State, where crops are restricted to only one cultivar – 'Roxo de Valinhos'. This cultivar was from a region close to the Adriatic Sea in Italy and was introduced in Brazil, in the region of Valinhos, at the beginning of the 20th century by the Italian Lino Bussato.

'Roxo de Valinhos' fig plant is vigorous, productive and adapted to the drastic pruning system; this practice was adopted to help control pests and diseases. This is the only culti‐ var that has economic value due to its rusticity, vigor, and productivity; in addition, it is a product sensitive to handling and easily perishable. Production can be directed to indus‐ try for the fabrication of green fig compote, jam and crystallized fig, or for consumption of raw fruits.

The fig tree is commercially cultivated in the Brazilian states Rio Grande do Sul (39.42%), São Paulo (35.15%), and Minas Gerais (18.75%). In São Paulo State, the production is mainly destined for the market of raw fruits, whereas in the other states it is directed to industrial processing. According to data from the Brazilian Ministry of Agriculture (2008), Brazil produced 26,476 t figs in 2006, in a 3,020ha area, resulting in an average national productivity of 8.8 t/ha.

The culture is interesting for Brazil as it may lead Brazilian exportations to be incorporated between harvests in Turkey, which is the world's main producer of figs. Brazil is a great fur‐ nisher of figs to the world; 20 to 30% of the total volume produced in the country is destined for exportation. Commercialization is done in boxes containing 1.6 Kg of the fruit [1].

#### **2.1. Potassium fertilization in fig orchards**

Little is known about the nutritional demands for the fig tree culture. The results available mostly discuss the use of organic fertilizers, where those appear as favorable practices, both in the development and the production of fig trees. Experiments with different sources and doses of nitrogen had also been widely performed, however, little is known about the de‐ mands of the other nutrients. According to [2], balanced and satisfactory mineral nutrition factors during the phase of formation of the plants assure good crops in the production phase of the plant.

Thus, in the absence of systematic studies for this purpose, the fertilizations of this fruit tree are performed mostly in an empiric way, mainly during implantation and formation of the trees. Likewise, nutritional diagnosis of plants through foliar analysis, although being a widely recognized valuable instrument for perennial plants, is incipient in the case of fig culture, often with conflicting values and absence in case of diagnosis with use of petioles.

Although the nutritional demands of the fig tree are of fairly knowledge, its measurement involves components of a very complex range, since the nutrient demands are closely relat‐ ed to the aspects of the species' physiology. During reproductive phase, the nutritional re‐ quirements have a component which is easily measurable and highly important in the evaluation of nutritional demands, the export of nutrients within fruit crops. However, dur‐ ing plant formation phase, the nutritional demands become difficult to determine since those are only for the growth and establishment of the plant, as well as the analyses of de‐ velopment the plants are rarely done in this period. In this phase excessive fertilization is performed according to visual diagnosis done by the producer, which is not uncommon.

### **2.2. Nutritional diagnosis and fertilization recommendations**

According to [3], the knowledge of any needs or excesses of chemical elements responsible for the metabolism of plants and, due to the vegetation and productivity of fruit trees, it con‐ stitutes a necessary and indispensable step for corrective measures, since the fertilizing rec‐ ommendations consist in the employment of fertilizer amounts, aiming to correct the element or limiting factor detected by the diagnosis.

The fertilizing recommendations during the formation period of the fig trees had been advo‐ cated exclusively from interpretations of soil analysis. In case of planting fertilizations, the recommendations are made by subjective criteria, not taking into consideration the content in the soil [4]. However, according to [3,5], soil analyses may be used to follow up the fertili‐ ty of the soil and fertilizing recommendations during the development of the plants, because when used concomitantly with diagnosis methods may yield better results. The nutritional state of the plant can reveal the availability of nutrients of the soil and the ability the plant has to absorb them. Yet, fertilizing recommendations based on nutrient demands for fruit production, growth of branches, trunk and roots, during the phase of plant formation, can‐ not be considered a practice sufficiently broad, since such requirements are hard to measure. According to [6,7], the nutritional demands are better evaluated for plants at full produc‐ tion, where the crops of unripe and ripe fruits constitute the main sources of nutrient ex‐ tracting sources.

#### **2.3. Effect of potassium fertilizer on the fig tree**

Due to scarce information on fertilization and nutrition of the fig tree, coupled to the evalua‐ tion of its effects on the nutritional state, a research was conducted using the levels of potas‐ sium fertilization, during the period of plant formation [8].

#### **2.4. Methodology**

The fig is one of the most popular food that has been sustaining humanity since the begin‐ ning of History. The fruit was used to feed advanced Olympic athletes and was offered to the winner as the first Olympic medal. The tree was described in many passages from the Bible as sacred and respected by man. During the period of the great discoveries, the fig was disseminated to the Americas. In Brazil, the fig tree was probably introduced by the first col‐

In Brazil, economic exploration of the fig tree only started from 1910, when it was first com‐ mercially cultivated in Valinhos region, São Paulo State, where crops are restricted to only one cultivar – 'Roxo de Valinhos'. This cultivar was from a region close to the Adriatic Sea in Italy and was introduced in Brazil, in the region of Valinhos, at the beginning of the 20th

'Roxo de Valinhos' fig plant is vigorous, productive and adapted to the drastic pruning system; this practice was adopted to help control pests and diseases. This is the only culti‐ var that has economic value due to its rusticity, vigor, and productivity; in addition, it is a product sensitive to handling and easily perishable. Production can be directed to indus‐ try for the fabrication of green fig compote, jam and crystallized fig, or for consumption

The fig tree is commercially cultivated in the Brazilian states Rio Grande do Sul (39.42%), São Paulo (35.15%), and Minas Gerais (18.75%). In São Paulo State, the production is mainly destined for the market of raw fruits, whereas in the other states it is directed to industrial processing. According to data from the Brazilian Ministry of Agriculture (2008), Brazil produced 26,476 t figs in 2006, in a 3,020ha area, resulting in an average national

The culture is interesting for Brazil as it may lead Brazilian exportations to be incorporated between harvests in Turkey, which is the world's main producer of figs. Brazil is a great fur‐ nisher of figs to the world; 20 to 30% of the total volume produced in the country is destined

Little is known about the nutritional demands for the fig tree culture. The results available mostly discuss the use of organic fertilizers, where those appear as favorable practices, both in the development and the production of fig trees. Experiments with different sources and doses of nitrogen had also been widely performed, however, little is known about the de‐ mands of the other nutrients. According to [2], balanced and satisfactory mineral nutrition factors during the phase of formation of the plants assure good crops in the production

Thus, in the absence of systematic studies for this purpose, the fertilizations of this fruit tree are performed mostly in an empiric way, mainly during implantation and formation of the trees. Likewise, nutritional diagnosis of plants through foliar analysis, although being a widely recognized valuable instrument for perennial plants, is incipient in the case of fig culture, often with conflicting values and absence in case of diagnosis with use of petioles.

for exportation. Commercialization is done in boxes containing 1.6 Kg of the fruit [1].

onizing expedition in 1532 in São Paulo State.

century by the Italian Lino Bussato.

of raw fruits.

194 Soil Fertility

productivity of 8.8 t/ha.

phase of the plant.

**2.1. Potassium fertilization in fig orchards**

The experiment was carried through in field conditions at the Orchard of Experimental Farm, of São Paulo State University, Faculty of Agronomic Sciences, Campus of Botucatu, São Paulo, Brazil, located at 220 51' 55" South Latitude, 480 26' 22" Western Longitude, with altitude of 830 meters. The predominant climatic type at the location, according to [9,10], based on the KOEPPEN international System, is included in the Cfb, namely the temperate climate without dry winter, mean temperature of the coolest months below 18ºC and the ones from the warmer months below 22ºC, with annual mean precipitation of 1314 mm, reaching in the driest month (August), a 26 mm average. The climate conditions observed during the conduction of the experiment are in Figures 1 and 2.

The soil is Rhodolic Haplo Udalf, according to the criteria established by [11]. The results of soil analysis of the 0-20 cm layer performed before and after saturation increasing by basic cations, according to the methodology in [12], are presented in Tables 1 and 2, respectively.

4.2 24.0 3.0 77.0 1.5 12.0 5.0 19.0 96.0 19.0

**Table 1.** Chemical characteristics of the soil where the experiment was performed before saturation increasing by

5.6 31.0 14.0 32.0 1.3 37.0 21.0 60.0 91.0 66.0

**Table 2.** Chemical characteristics of the soil after saturation increasing by bases and planting fertilization. UNESP/

The experiment was performed adopting the randomized block design, in an experimental scheme of subdivided parcels along the time, with four repetitions. The parcels were com‐ posed by potassium levels, sub-parcels by years and sub-parcels by harvesting months. The experimental unit was composed by three useful plants of the fig tree from cv ′Roxo de Va‐ linhos′, completely surrounded by border plants, in 3 x 2m spacings among plants and

The main treatments, potassium fertilization levels (Table 3), were administered in the peri‐ od from August to September of the agricultural cycles using increasing doses in arithmetic

> **Treatments Potassium Levels** K 0 (Witness) Zero K2O K I 30g K2O plant-1 K II 60g K2O plant-1 K III 90g K2O plant-1 K IV 120g K2O plant-1 K V 150g K2O plant-1

Source: Soil Fertility Laboratory – Department of Environmental Resources – Area of Soil Science.

Source: Soil Fertility Laboratory – Department of Environmental Resources – Area of Soil Science.

progression, in which the levels of the second cycle were equal to the first.

**Table 3.** K2O levels applied in the experiment. UNESP/Botucatu-SP, Brazil, 2012. [8].

**H + Al K Ca Mg SB CTC V % mmolcdm-3**

Potassium Fertilization on Fruits Orchards: A Study Case from Brazil

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197

**H + Al K Ca Mg SB CTC V % mmolcdm-3**

for each experimental unit.

**pH CaCl2**

**pH CaCl2** **MO g dm-3**

bases. UNESP/Botucatu-SP, Brazil, 2012. [8].

**MO gdm-3 P resin**

Botucatu-SP, Brazil, 2012. BRIZOLA et al. (2005)[8].

**mgdm-3**

among lines, thus composing an useful area of 18m2

**P resin mg dm-3**

**Figure 1.** Maximum, mean and minimum temperatures observed during the conduction of the experiment. UNESP/ Botucatu - SP, Brazil, 2012.[8].

**Figure 2.** Pluviometric precipitations and evapotranspiration of the fig tree culture during the conduction of the ex‐ periment. UNESP/Botucatu - SP, Brazil, 2012.[8]. Source: Evapotranspiration of Class A Tank (ECA) - Area of Environ‐ mental Sciences (FCA). Evapotranspiration from the Culture (ETc) – Calculated by Culture Coefficient (Kc) data.

The soil is Rhodolic Haplo Udalf, according to the criteria established by [11]. The results of soil analysis of the 0-20 cm layer performed before and after saturation increasing by basic cations, according to the methodology in [12], are presented in Tables 1 and 2, respectively.


Source: Soil Fertility Laboratory – Department of Environmental Resources – Area of Soil Science.

climate without dry winter, mean temperature of the coolest months below 18ºC and the ones from the warmer months below 22ºC, with annual mean precipitation of 1314 mm, reaching in the driest month (August), a 26 mm average. The climate conditions observed

**Figure 1.** Maximum, mean and minimum temperatures observed during the conduction of the experiment. UNESP/

**Figure 2.** Pluviometric precipitations and evapotranspiration of the fig tree culture during the conduction of the ex‐ periment. UNESP/Botucatu - SP, Brazil, 2012.[8]. Source: Evapotranspiration of Class A Tank (ECA) - Area of Environ‐ mental Sciences (FCA). Evapotranspiration from the Culture (ETc) – Calculated by Culture Coefficient (Kc) data.

during the conduction of the experiment are in Figures 1 and 2.

Botucatu - SP, Brazil, 2012.[8].

196 Soil Fertility

**Table 1.** Chemical characteristics of the soil where the experiment was performed before saturation increasing by bases. UNESP/Botucatu-SP, Brazil, 2012. [8].


Source: Soil Fertility Laboratory – Department of Environmental Resources – Area of Soil Science.

**Table 2.** Chemical characteristics of the soil after saturation increasing by bases and planting fertilization. UNESP/ Botucatu-SP, Brazil, 2012. BRIZOLA et al. (2005)[8].

The experiment was performed adopting the randomized block design, in an experimental scheme of subdivided parcels along the time, with four repetitions. The parcels were com‐ posed by potassium levels, sub-parcels by years and sub-parcels by harvesting months. The experimental unit was composed by three useful plants of the fig tree from cv ′Roxo de Va‐ linhos′, completely surrounded by border plants, in 3 x 2m spacings among plants and among lines, thus composing an useful area of 18m2 for each experimental unit.

The main treatments, potassium fertilization levels (Table 3), were administered in the peri‐ od from August to September of the agricultural cycles using increasing doses in arithmetic progression, in which the levels of the second cycle were equal to the first.


**Table 3.** K2O levels applied in the experiment. UNESP/Botucatu-SP, Brazil, 2012. [8].

Potassium fertilizations began from seedling fixation, potassium chloride used as a nu‐ trient supplier, the levels during the first year adopted according to the recommendation in [4], with two levels lower and three levels higher than the 60 g K2O/plant recommenda‐ tion. For levels higher than 60g K2O plant-1, the applications were divided in three occa‐ sions, with 20-day intervals. Nitrogenized fertilizations were also used using ammonium sulphate in four applications, placing 15g nitrogen plant-1 at each occasion. The fertiliza‐ tions were applied in the projection of the crown of the tree and superficially incorporat‐ ed using a shovel in the two years of conduction of the experiment. The use of phosphorus was done only during the plantation, at the amount of 100g plant-1 of P2O5, applying simple superphosphate.

The evaluation of the nutritional state of fig tree plants was performed through the diag‐ nosis of the leaf and petiole, in three months within each evaluation year: October, De‐ cember and February. The analyses of macronutrient content and branches and fruit accumulations were performed to evaluate the extraction of nutrients by the fig tree. The evaluations were obtained during the growth and plant production periods, the collec‐ tions performed in three periods (October, December and February), evaluating: number of leaves, length of branches (cm), trunk diameter, dry matter of branches and production of fruits.

**Figure 3.** Effects of potassium fertilization in the dry matter of branches of the fig tree. FCA/UNESP/Botucatu,

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199

**Figure 4.** Effects of potassium fertilization in the number of leaves by fig tree branch. FCA/UNESP. Botucatu, SP,

Comparing the results found for foliar contents in the experiment to those suggested by [16] as optimal for well-nourished plants, it is observed that only nitrogen and potassium presented levels lower than those found by the authors, whereas in such concentrations, according to the same authors, those nutrients were already approaching deficiency zone. In [17], foliar contents indicated as satisfactory for fig tree culture are in ranges of 22-24

SP, Brazil. [8].

Brazil. 2012. [8].

#### **2.5. Results**

The results obtained evidenced that the content of macronutrients in branches were not in‐ fluenced by potassium fertilization in the crown. According to [13,14], the interactions be‐ tween ions assume the existence of a certain relationship within those in soil solution (nutrient availability), this relationship being able to manifest itself in the form of nutritional imbalance, where the leaves are the first organs to manifest those changes, both at the level of contents and visual symptoms. Regarding the macronutrient content in branches, those were not influenced by potassium fertilizations. Thus, it can be accepted that such interac‐ tions in levels of content in branches are observed in more prolonged conditions of nutri‐ tional imbalance.

The growth of branches and the number of leaves by branch increased with fertilization and, accordingly, positive responses were obtained with potassium fertilization in the production of dry matter of branches and fruits (Figures 3 and 4).

According to [13], potassium deficiencies may reduce the photosynthetic activity and in‐ crease respiration, reducing the supply of carbohydrates and with consequent effects on the growth of the plants. For [15], the physiological functions played by potassium are directly involved in protein synthesis, in the use of water and in the translocation of carbohydrates, conditions which, when perfectly functional, may lead to plant growth.

The evaluation of structures of the plant showed that the leaves were the organs that pre‐ sented the highest levels of nitrogen, phosphorus, calcium and magnesium, while the fruits were the organs that presented the lowest levels of macronutrients (Table 4).

Potassium fertilizations began from seedling fixation, potassium chloride used as a nu‐ trient supplier, the levels during the first year adopted according to the recommendation in [4], with two levels lower and three levels higher than the 60 g K2O/plant recommenda‐ tion. For levels higher than 60g K2O plant-1, the applications were divided in three occa‐ sions, with 20-day intervals. Nitrogenized fertilizations were also used using ammonium sulphate in four applications, placing 15g nitrogen plant-1 at each occasion. The fertiliza‐ tions were applied in the projection of the crown of the tree and superficially incorporat‐ ed using a shovel in the two years of conduction of the experiment. The use of phosphorus was done only during the plantation, at the amount of 100g plant-1 of P2O5,

The evaluation of the nutritional state of fig tree plants was performed through the diag‐ nosis of the leaf and petiole, in three months within each evaluation year: October, De‐ cember and February. The analyses of macronutrient content and branches and fruit accumulations were performed to evaluate the extraction of nutrients by the fig tree. The evaluations were obtained during the growth and plant production periods, the collec‐ tions performed in three periods (October, December and February), evaluating: number of leaves, length of branches (cm), trunk diameter, dry matter of branches and production

The results obtained evidenced that the content of macronutrients in branches were not in‐ fluenced by potassium fertilization in the crown. According to [13,14], the interactions be‐ tween ions assume the existence of a certain relationship within those in soil solution (nutrient availability), this relationship being able to manifest itself in the form of nutritional imbalance, where the leaves are the first organs to manifest those changes, both at the level of contents and visual symptoms. Regarding the macronutrient content in branches, those were not influenced by potassium fertilizations. Thus, it can be accepted that such interac‐ tions in levels of content in branches are observed in more prolonged conditions of nutri‐

The growth of branches and the number of leaves by branch increased with fertilization and, accordingly, positive responses were obtained with potassium fertilization in the production

According to [13], potassium deficiencies may reduce the photosynthetic activity and in‐ crease respiration, reducing the supply of carbohydrates and with consequent effects on the growth of the plants. For [15], the physiological functions played by potassium are directly involved in protein synthesis, in the use of water and in the translocation of carbohydrates,

The evaluation of structures of the plant showed that the leaves were the organs that pre‐ sented the highest levels of nitrogen, phosphorus, calcium and magnesium, while the fruits

applying simple superphosphate.

of fruits.

198 Soil Fertility

**2.5. Results**

tional imbalance.

of dry matter of branches and fruits (Figures 3 and 4).

conditions which, when perfectly functional, may lead to plant growth.

were the organs that presented the lowest levels of macronutrients (Table 4).

**Figure 3.** Effects of potassium fertilization in the dry matter of branches of the fig tree. FCA/UNESP/Botucatu, SP, Brazil. [8].

**Figure 4.** Effects of potassium fertilization in the number of leaves by fig tree branch. FCA/UNESP. Botucatu, SP, Brazil. 2012. [8].

Comparing the results found for foliar contents in the experiment to those suggested by [16] as optimal for well-nourished plants, it is observed that only nitrogen and potassium presented levels lower than those found by the authors, whereas in such concentrations, according to the same authors, those nutrients were already approaching deficiency zone. In [17], foliar contents indicated as satisfactory for fig tree culture are in ranges of 22-24 for N; 1.2-1.6 for P; 12-17 for K; 26-34 for Ca and 6-8 g Kg-1 for Mg, whereas, in compari‐ sons, only for Ca and Mg content lower than those indicated by the authors were detect‐ ed. In comparison to the values indicated by [18] for foliar contents, calcium and magnesium presented values lower than those considered optimal for the culture, howev‐ er, there was no perception of any manifestations of nutritional deficiency symptoms con‐ nected to those two nutrients, even in the treatment where the highest doses of potassium were applied.

**Ratios Between Nutrients Correlation Coefficient (r) Significance test (F)**

N (leaf x petiole) 0.738 0.806 0.009\*\* 0.000\*\* P (leaf x petiole) 0.591 0.634 0.040\* 0.025\* K (leaf x petiole) 0.715 0.761 0.001\*\* 0.002\*\* Ca (leaf x petiole) 0.771 0.829 0.003\*\* 0.000\*\* Mg (leaf x petiole) 0.612 0.651 0.034\* 0.018\* S (leaf x petiole) 0.658 0.660 0.018\* 0.019\* K (leaf x soil) 0.386 0.773 0.215ns 0.003\*\* K (petiole x soil) 0.417 0.736 0.176ns 0.009\*\*

ns = Non-significant a P>5% by F test; \* Significant at 5% of likelihood; \* \* Significant at 1% of likelihood.

**Table 5.** Correlations of macronutrient content in leaves and petioles of fig tree undergoing six levels of potassium in

The results of fruit production (Figure 5) show that increases in potassium levels in topdressing increased linearly with the production; however, the trend of the equation indi‐ cates an adjustment for a cubic equation when using higher levels of K2O. Thus, the availabilities of potassium above 90 g K2O plant-1 could be considered as luxury consump‐

**Figure 5.** Effects of potassium fertilization in total production of fruits of developing fig tree. FCA/UNESP/Botucatu,

**Second crop cycle 2001/2002 2002/2003**

Potassium Fertilization on Fruits Orchards: A Study Case from Brazil

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201

**First crop cycle**

top-dressing fertilization. UNESP/Botucatu-SP, Brazil, 2012. [8]

SP, Brazil. 2012. [8].

tion, since those would not be increasing the production values.


Means followed by the same letter, in the same line, are not significantly different from the means by contrast, at the level of 5% of likelihood by F test.

**Table 4.** Mean content of macronutrients in leaves, petioles, branches and fruits of fig tree undergoing six levels of potassium in top-dressing fertilization. UNESP/Botucatu-SP. [8].

Regarding the contrasts of means between the content in leaves and petioles, it was noticed that the potassium and sulfur content were lower in leaves, whereas for magnesium, the contents were not different in leaves and petioles. For nitrogen, phosphorus and calcium the foliar contents were higher than those found in petioles, results in agreement with those found by [16], where contents of N of 33.9 and 15.1; P of 2.0 and 1.6; K of 26.8 and 45.9; Ca of 16.7 and 11.9; Mg of 6.3 and 8.4; and S of 2.0 and 4.4 g Kg-1 were found in leaves petioles, respectively.

It was also observed that macronutrient content in leaves presented good correlations to those determined in petioles, and the petioles had better correlation coefficients with dry matter production and fruit production, making them preferential for the analysis of nutri‐ tional status of fig trees being formed (Table 5). Such results are in agreement with literature data, which indicate that the petiole is the most appropriate organ for evaluation of potassi‐ um in the plant [16,17,19].


for N; 1.2-1.6 for P; 12-17 for K; 26-34 for Ca and 6-8 g Kg-1 for Mg, whereas, in compari‐ sons, only for Ca and Mg content lower than those indicated by the authors were detect‐ ed. In comparison to the values indicated by [18] for foliar contents, calcium and magnesium presented values lower than those considered optimal for the culture, howev‐ er, there was no perception of any manifestations of nutritional deficiency symptoms con‐ nected to those two nutrients, even in the treatment where the highest doses of potassium

**Nutrient (g Kg-1) Leaves Petioles Branches Fruits**

Nitrogen 25.57 A 11.14 B 10.36 B 7.995 C

Phosphorus 2.096 A 1.475 B 1.033 BC 0.777 C

Potassium 21.89 B 31.82 A 2.213 D 8.620 C

Calcium 19.25 A 10.75 B 6.982 C 1.863 D

Magnesium 5.675 A 4.262 A 1.981 B 0.727 B

Sulfur 1.707 B 3.064 A 0.960 B 0.766 B

Means followed by the same letter, in the same line, are not significantly different from the means by contrast, at the

**Table 4.** Mean content of macronutrients in leaves, petioles, branches and fruits of fig tree undergoing six levels of

Regarding the contrasts of means between the content in leaves and petioles, it was noticed that the potassium and sulfur content were lower in leaves, whereas for magnesium, the contents were not different in leaves and petioles. For nitrogen, phosphorus and calcium the foliar contents were higher than those found in petioles, results in agreement with those found by [16], where contents of N of 33.9 and 15.1; P of 2.0 and 1.6; K of 26.8 and 45.9; Ca of 16.7 and 11.9; Mg of 6.3 and 8.4; and S of 2.0 and 4.4 g Kg-1 were found in leaves petioles,

It was also observed that macronutrient content in leaves presented good correlations to those determined in petioles, and the petioles had better correlation coefficients with dry matter production and fruit production, making them preferential for the analysis of nutri‐ tional status of fig trees being formed (Table 5). Such results are in agreement with literature data, which indicate that the petiole is the most appropriate organ for evaluation of potassi‐

were applied.

200 Soil Fertility

level of 5% of likelihood by F test.

respectively.

um in the plant [16,17,19].

potassium in top-dressing fertilization. UNESP/Botucatu-SP. [8].

**Table 5.** Correlations of macronutrient content in leaves and petioles of fig tree undergoing six levels of potassium in top-dressing fertilization. UNESP/Botucatu-SP, Brazil, 2012. [8]

The results of fruit production (Figure 5) show that increases in potassium levels in topdressing increased linearly with the production; however, the trend of the equation indi‐ cates an adjustment for a cubic equation when using higher levels of K2O. Thus, the availabilities of potassium above 90 g K2O plant-1 could be considered as luxury consump‐ tion, since those would not be increasing the production values.

**Figure 5.** Effects of potassium fertilization in total production of fruits of developing fig tree. FCA/UNESP/Botucatu, SP, Brazil. 2012. [8].

In [20] no effects were obtained for the higher doses of potassium, although the employment of the dose of 60g K2O plant-1 had been about 40% higher than the dose of 30g K2O plant-1. The authors justified such results due to the high variation coefficient obtained for the anal‐ ysis of harvesting of unripe fruits. For [3], the effects of potassium fertilizations on fruit trees are more conditioned to aspects of quality than quantity, since this element is not in limiting amounts for the development of the plant.

creases sugar translocation to sink tissues, promoting their growth [24]. Thus, fruits from K-

Potassium Fertilization on Fruits Orchards: A Study Case from Brazil

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

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According with [29,30], an excess of K can affect the calcium (Ca) nutrition, increasing the intensity of physiological disorders related this nutrient, including the bitter pit, cork spot and lenticel blotch pit, among others. Increasing K as well as N rates can decrease flesh firm‐

Fertilizer recommendations for apple in Santa Catarina (SC) and Rio Grande do Sul (RS) states Brazil are based on soil and leaves chemical analysis, shoot growth and orchard pro‐ ductivity [31]. The amount recommended for each year varies from 0 to 100 kg ha-1. These recomenadtion were obtained from results of research conducted in Fraiburgo/SC and Vaca‐ ria/RS, or adapted from other production regions around the world. Reginal fertilization test are quite important to São Joaquim/SC, considering that this region presents very stony and shallow Inceptisols and the mean temperatures are lower when in comparison to other pro‐

In [32] made an research with the objective to evaluate the effects of long-term annual addi‐ tions of K to the soil on yield, fruit size, mineral composition and Ca-related disorders of 'Fugi' apples for São Joaquim, Santa Catarina state, Southerm Brazil (28º 17′ S, 49º 55′ W). The experiment was conducted in the growing seasons from 1998 to 2006 in three commer‐ cial orchards of 12, 16 and 19 years old. Clay content and chemical characteristics of the soil from the experiment orchards, at the beginning of the experiment, are presented in Table 6.

The experimental plots comprised five plants, spaced 4.5 m between plants by 6.0 m be‐ tween rows in one orchard and 3.0 by 6.0m in the other two, with the three central plants used as measurement plants. Trees were trained on a central leader system and received the same pruning and thinning practices as recommended for apple commercial orchards.

**Attribute Orchard 1 Orchard 2 Orchard 3** pH (H2O) 6.8 6.4 6.6 P (mg dm-3) 33.0 45.0 63.0 K (mg dm-3) 141.0 240.0 258.0

Ca (mmolc dm-3) 89.0 112.0 119.0 Mg (mmolc dm-3) 60.0 62.0 64.0

Organic matter (g dm-3) 50.0 49.0 65.0

**Table 6.** Soil testing results before experiment implementation (1998). [32].

Clay 9 g dm-3) 300.0 380.0 300.0

deficient plants have reduced size [25,26,27,28]. Which can reduce overall yield [22].

ness, reducing the storage life of apples.

duction regions in Brazil.

**3.2. Methodology**

#### **2.6. Conclusions**

The results showed that potassium fertilizations provide increases of production of dry mat‐ ter of branches and fruits, where better results were associated with levels of 90 g K20 plant-1, in a stand of 1600 plants per hectare and in soils under conditions of low and medi‐ um fertility in potassium.
