Yellow passion fruit (Passiflora edulis SIMS f. Flavicarpa DEG) is one of the most important fruit exploitation in Brazil, due to its use in nature as well as industrial beverages, besides excellent perspectives for exporting concentrated juice to Europe and USA (Ataíde et al., 2012).

Brazil is the biggest producer and consumer of this fruit with 61,842 ha of growing area and estimated fruit production of 923,035 ton per year. The northeast of Brazil is the main producing area with 46,159 ha and 671,421 ton of fruit harvested, which correspond to 63% of national production (IBGE, 2014). According to Silva et al. (2015), the passion fruit has significant social and economic importance in Brazil   and it is a versatile fruit that can be marketed in different forms, such as raw fruit, frozen pulps, juice, jams, yogurts, milk drinks and ice cream.

In Brazilian semiarid, specifically in the Paraíba State, the amount and quality of water are the factors that limit agricultural production. At this region the limited and irregular rainfall difficult the development of a non-irrigated fruit plant cultivation.

Nevertheless, in other Brazilian regions, where rainfall is regular year-round, passion fruit plants can be cultivated without irrigation techniques or with water supplementation when rainfall is below of the plant necessities (Arêdes et al., 2009). In this context, there is a history of research on the technical feasibility of irrigation methods according to Valipour (2012a) in determining optimal values for these systems. Thereafter, many attempts have been made to access appropriate design of sprinkle and trickle irrigation system (Valipour, 2012b).

By the benefits of localized irrigation system into the other techniques especially surface irrigation, more accurate design of this systems for saving in water resources, increasing irrigation efficiency, and finally encourage farmers to use of this system in order to save water resources (Valipour, 2012a).

Research with yellow passion fruit, in several regions of Brazil, have shown that this specie, in spite of having a high production cost and also a negative price fluctuations in the consumer market, has economic potential to increase employment and as well financial return; which has been matched and has often exceeded the rates achieved by the main crops in the country such as other species of fruit trees, cereals and vegetables crops (Kits et al., 1996; Araújo Neto et al., 2008; Arêdes et al., 2009; Hafle et al., 2011).

Economic analyses of the production chain is a significant index to show the implementation of a new technology and it has been studied for some researchers as Araújo Neto et al. (2008), Arêdes et al. (2009), Hafle et al. (2011) and Silva et al. (2015). The viability of a production chain depends directly on correct agricultural management, however, one should take into account all factors involved in this process (Hafle et al., 2012). Although there are researches with irrigated passion fruit cultivation (Araújo et al., 2012; Dias et al., 2012; Freire et al., 2014), there is still the lack of information about using this technology and the profitability of BRS Sol do Cerrado and BRS Gigante Amarelo hybrids under Paraíba State semi-arid conditions. These information are necessary to the farmers because they will help them to make the right decision of the resources used in its production, as also improving the performance of this fruit plant by enabling the expansion of areas under cultivation and guide the proper choice of the variety most adapted to the soil and climate of the semi-arid region.

Thus, this research was carried out to evaluate the economic viability of the application of different irrigation depths in yellow passion fruit crop in the semi-arid region of Paraíba State.

(2014), the Penman-Monteith method is suitable for estimating the water requirement of crops, despite showing variation around 10% compared with the lysimetric measures. Although this method has been applied in various regions of the world, it needs too many parameters to estimate reference crop evapotranspiration (Valipour 2015), hence it is important to assess its use in this research.

In which: ETo = reference transpiration (mm day^-1); Rn = net radiation on culture surface (MJ m^-2 day^-1); heat flow in the soil (MJ m^-2 day^-1); ∆ = slope of the vapor pressure curve versus air temperature (kPa °C^-1); U₂ = wind speed measured at two meters high (m s^-1); T = average air temperature (°C); es = water vapor saturation pressure (kPa); ea = actual pressure of water vapor (kPa); γ = psychrometric factor (MJ kg^-1).

The crude depth, water application rate and the time of irrigation were determined by Equations 2, 3 and 4, respectively (Mantovani et al., 2006).

In which: LB = crude depth (mm); ETo = reference evapotranspiration according to Penman-Monteith (mm); Kc = crop coefficient, considered 1 for application of ETo; KL = percentage of wetted area by the water emitter; Pe = rainfall during the experimental period (mm); Ef = irrigation method efficiency (decimal).

In which: Ia = water application rate (mm h^-1); n = number of emmiter per plant; v = emitter flow (L h^-1); ec = area occupied by the plant (m²).

In which: Ti = irrigation time (h); LB = crude depth (mm day^-1); Ia = water application rate (mm h^-1).

Management of the application of different water depths was carried out by varying the number of drippers per plant, using 1, 2, 3 and 4 pressure compensating drippers, with a nominal flow rate of 4 L h^-1, corresponding to depth of 33, 66, 100 and 133% of ETo respectively (Figure 1B).

The fertilizers were applied through fertigation, every 15 days, in such a way to distribute nutrients throughout the crop cycle. Thus, a Ventury injector was used with a flow rate of 70 L h^-1.

 

Profitability and economic analysis

Fruit yield was estimated taking into account weight and number of fruits per plant (Mg ha^-1), and the estimated net income (RL) (Equation 5) was obtained through the response function (Y(W) = β₀ + β₁W₁ + β₂W₂ + e), cost of water (CW) =  (Andrade Júnior et al., 2001) and the cost of production (CP) (Pimentel et al., 2009).

In which:

Y(W) - Fruit yield as a function of applied water depth (Mg ha^-1);

β₀, β₁ e β₂ – Regression parameters;

W₁ e W₂ – Irrigation depths;

e – Random error;

CW = Cost of irrigation water (US$ mm^-1);

CEE = Electricity consumption during the crop cycle (kwh ha^-1);

LL = Total water depth applied during the crop cycle (mm);

Pee = Price of kwh (US$ kwh^-1), was obtained from Paraíba electrical power company;

P = Price of passion fruit on Catolé do Rocha county market (Paraíba State) was calculated on the basis on a weekly survey in street markets. The price paid to the farmer, that is, 50% of the average price paid at these locations during the years 2011 and 2012 was also taken into account.

To analyze passion fruit production costs (CP), the expenditures and charges were grouped into the related categories:

(a) Effective operational cost (EOC): this comprises direct costs with financial disbursement to the activities from soil tillage and fruit harvest;

(b) Costs and administrative expending: it reflects fixed costs or indirect expenses for interest, social charges, administration fee and equipment depreciation:

(b.1) Remuneration of the farmer's capital calculated on the basis of 0.5% per month on the COE's half value: it aims to remunerate the alternative use of farmer's capital if he or she chooses for financial savings application;

(b.2) Land remuneration that correspond to the real value of 1.0 ha rentals in the region;

b.3) Depreciation of machinery and equipment: this includes financial resources to acquire spare parts which should correspond to 10% of the irrigation equipment;

b.4) Management fee calculated on the basis of 6% of the COE; and

(c) Total operating costs (COT), corresponding to the sum of the overall expenses of (a) + (b).

 

In addition to net income, other profitability indicators such as benefit/cost relation, equilibrium price and index of profitability were calculated by the following equations:

In which:

B/C = benefit/cost relation (non-dimensional);

RB = gross income (US$ ha^-1 year^-1);

CTP = total production costs (US$ ha^-1 year^-1);

PE = equilibrium price (US$ Mg^-1);

Y w= estimated productivity (Mg ha^-1);

IL = profitability index (%).

Cost of production

On Table 1 are shown the production costs for both ‘BRS Sol do Cerrado’ and ‘BRS Gigante Amarelo’ passion fruits hybrids. The cost generated by this factor is related to the price of seed, being equal to both genotypes. It should be observed it was included at disbursement stage of seedlings production, as a component of costs to calculate the effective operational cost (COE); it had the absolute value of US$ 5,055.00 ha^-1 year^-1, which corresponded to 86.43, 85.16, 83.19 and 81.84% of the total production cost (CTP), in relation to water replacement depths 33, 66, 100 and 133% of ETo, respectively (Table 1). When the COE was fractionated, it was observed that the inputs accounted for 39 and 36.93% of the total cost of production process for the irrigation depths of 33 and 133%, respectively. These values corresponded to 1.95, 3.29, 5.41 and 7.07% from total cost of fruit production, respectively.

 

 

 

 

Technical indexes used to calculate costs of the research were obtained by monitoring the current field experiment. Labor, tractor rental and inputs considered were those used in Catolé do Rocha County-PB from 2009 to 2012. COE (effective operational cost), CEA (costs of administrative burden), CTA (Water total cost) and CTP (total cost of production).

Regarding costs of administrative burden (CEA), this value was US$ 685.50 ha^-1. To the costs of irrigation water, these values were US$ 108.26 (33% of ETo), US$ 195.31 (66% of ETo), US$ 328.60 (100% of ETo) and US$ 436.52 per hectare (133% of ETo), which corresponded  to  1.95,  3.29, 5.41 and 7.07% of the total production cost for replacement depths 33, 66, 100 and 133% of ETo, respectively (Table 1).

Passion fruit hybrids cultivation had a total production cost of 5,848.85 US$ ha^-1 (33% of ETo), 5,935.81 US$ ha^-1 (66% of ETo), 6,069.10 US$ ha^-1 (100% of ETo) and 6,177.02 US$ ha^-1 (133% of ETo) (Table 1).

 

Yield and economic indicators

Regarding economic indicators (Table 2), there was no economic deficit for any of the hydric replacement depths studied. The lower net income (302.45 US$ ha^-1 year^-1) was attained by 'BRS Sol do Cerrado' irrigated with 33% of ETo. The bigger net income (9,831.0 US$) was also attained by this hybrid irrigated with 133% of ETo. It was observed that the best benefit/cost relation with 2.59 value for that same water replacement, which shows for each US$ 1.00 invested generated a net income of US$ 1.59.

 

 

 

 

The higher profitability index (61.41%) was attained by ‘BRS Sol do Cerrado’ under 133% ETo of water replacement, however, under 33% ETo, the highest profitability index (37.30) was obtained by ‘BRS Gigante Amarelo’, higher than ‘BRS Sol do Cerrado’ under lower water availability. For equilibrium price, it was observed that when ‘BRS Sol do Cerrado’ was irrigated with 133% of ETo, the price paid by the ton of fruit decreased the price from US$ 541.56 to US$ 220.60, even so, this cultivation system ensures the production costs.

When the productivity was reduced due to water stress by low water availability to plants (from 28.00 and 22.6 Mg ha^-1 at 133% of ETo to 10.80 and 16.30 Mg ha^-1 at 33% of ETo by ‘BRS Sol do Cerrado’ and ‘BRS Gigante Amarelo’, respectively), the price paid for the product was the determining factor for which there was no prejudice to the cultivation system (Table 2). However, under water scarcity the 'BRS Gigante Amarelo' shows higher profitability index per unit of water depth applied (Figure 2).

 

 

Differences regarding the total production cost occurred due to the amount of water applied to replace the hydric status of the plants, taking into account that its cost is based on the amount of electricity used during the water pumping process from water source to the plants.

Some researchers such as Kits et al. (1996) have evaluated agricultural and economic aspects of yellow passion fruit plants, whom, in a study on planting densities, observed that expenses on inputs and labor accounted for 98 and 97% of the total cost of production, when the fruit plants were grown at a spacing of 2 m x 1.25 m and 2 m × 3.75 m, respectively. Araújo Neto et al. (2008) reported that inputs along with labor were 57.83% compared to minimal cultivation and 60.46% compared to conventional tillage. Hafle et al. (2011) reported that passion fruit plants training pruning account for 73.9% from inputs along with labor.

In this context, labor costs studied in this research (around 80%) are less than those achieved by previous authors. This current result may be related to the growing technology in use, that is, one in which weeds are controlled by herbicide applied in the planting lines and mechanical mowing between planting lines which requires few labor. These agricultural practices comprise labor price and machinery working time. Moreover, the use of genetic material more resistant to pests and diseases decreased spraying during passion fruit growing and, therefore, the use of labor.

The economic profitability is dependent on the quantity produced and the price paid for the product. In relation to the passion fruit growing system in the semiarid region of Paraíba State, good productivity was observed considering mainly the potential of the hybrids evaluated in this study under irrigation.

By analyzing yellow passion fruit profitability, Kits et al. (1996) recorded net income corresponding to US$ 3,560.68 ha^-1. Araújo Neto et al. (2008) cited a higher value of net income around US$ 5.524,77 ha^-1. In another study, Arêdes et al. (2009) found a net income of US$ 5,749.29 ha^-1 and the benefit/cost relation of 1.24. The results found in this study (US$ 8,196.7 ha^-1 and US$ 9,831.8 ha^-1) mainly with ‘BRS Sol do Cerrado’ were higher than those presented by Kits et al. (1996) Araújo Neto et al. (2008) and Arêdes et al. (2009).

This may be related to the high productivity of the genotypes in this research and the high price paid for the fruits in the local market. These results show that irrigated fruit activity enables good economic returns, generates currency from outside and jobs mainly in areas where irrigation technology can be used, promoting greater water savings and economic returns.

Moreover, the productivity of ‘BRS Gigante Amarelo’ was higher than the ‘BRS Sol Cerrado’ under lower water availability. In this case, ‘BRS Sol Cerrado’ is more productively irrigated with larger volume of water, but water use efficiency is reduced. On the other hand, increase in productivity may not compensate for increase in water availability for this genotype as well as reduce its efficient use (Sousa et al., 2005).

According to Sousa et al. (2005), the water use efficiency relates accumulation of biomass or commercial production to the amount of water applied or evapotranspired by the crop. Thereafter, proper irrigation management stands out in irrigated agriculture for improved efficiency in water use. Among the means and techniques used to increase the water use efficiency in irrigated agriculture, is the use of drip irrigation and water supply along with high frequency and low amount.

Irrigated passion fruit cultivation provides economic returns in the semiarid region of Paraíba State. The best economic results were obtained with 'BRS Sol do Cerrado' under irrigation depth of 133% of ETo. Under water scarcity the 'BRS Gigante Amarelo' shows higher profitability index per unit of water depth applied. 

The authors have not declared any conflict of interest.

 

The authors thank FAPESQ, CNPq and PROPESQ/UEPB for the financial support as well as Dr. Fabio Gelape Faleiro (Embrapa/Cerrados) who donated the seeds used in this research.