**3.3. Results**

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‐ pared to trees not receiving K in these years.

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

Potassium Fertilization on Fruits Orchards: A Study Case from Brazil

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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

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

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

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

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

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‐

with a corresponding increase in collection of starch in leaves and stem [38].

information about the effects of different sources of K on fruit yield.

and others producing fibers excellent for cordage [33].

status of the plant and in measures of growth [36].

to normal packaging and labeling requirements.

everywhere.

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‐ ment (Table 6).

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).


**Table 7.** Average annual and cumulative fruit yield (1998-2006) for 'Fugi', as affected by annual surface adition of K. [32].

#### **3.4. Conclusions**

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