Production of Cashew Rootstocks Submitted to Organic and Mineral Fertilization

The use of grafted seedlings is a cultural practice that aims at the optimization of agricultural production, and materials of organomineral added to the substrate can help in the well development. The aim of this study was to evaluate the effect of the application of increasing doses of organic and mineral material on the development of cashew rootstocks. The test was conducted in the experimental area of the Federal University of Campina Grande (UFCG), campus Pombal-PB in the period from July to September 2017. The treatments were constituted of five increasing doses of organic matter (0, 100, 200, 300 and 400 g of bovine manure) and four levels of mineral fertilizer (0, 1, 2 and 3 g of NPK). The design was in randomized blocks, distributed in factorial 5 × 4, with 4 replications. For the planting, it was used creole seeds originary of the city of Livramento do Cariri Paraibano and substrate composed by sand texture Franco sandy. At 60 days after sowing, the following variables were analyzed: plant height (cm), leaf diameter (mm), number of leaves, leaf area (cm), fresh and dry mass, leaf, stem, shoot (g), percentage of biomass (%) and quality index of seedlings. Based on the results obtained, it is concluded that the organic and mineral combination (1 g of NPK and 200 g of bovine manure) provided the greatest increases in vegetative growth characteristics and quality of rootstocks in the cashew tree.


Introduction
The cashew tree (Anacardium occidentale L.), is a culture that has your center of origin in the Northeast of Brazil, where is very adapted to the semi-arid conditions, and as consequence produces nutritious pseudofruits, that present great appreciation mainly in the local market (Araújo, 2013).This cultivation represents great importance in socioeconomic terms, since in addition to the pseudofruit, since products such as the almond present in the chestnut and the liquid coming from the bark are included as raw material for industries (Ferreira et al., 2016a).
The productivity of cashew nuts in Brazil in the 2016 harvest was 228,796 t ha -1 (IBGE, 2016).In the Northeast, farms and agribusiness located in urban areas are benefiting from the cashew cultivation and extraction of brown, forming thus and activity that provides income generation, employment and development, especially in states such as Ceará, Rio Grande do Norte and Piauí (Araújo, 2013(Araújo, , 2014)).However, because the cashew is a heterozygous species, if it was propagated with seed, there will be the formation of plants with different genotypes and phenotypes, resulting in diferent orchards (due to high fruit variability and lack of synchrony during its development phases), low productivity and increased costs, thus hindering the commercial exploitation of caju or to be processed (Cavalcanti Junior, 2013).cost to the producer, favors substrate drainage, increases water retention capacity, stimulates root system development, and provides nutrients in a graduated way.While, the use of NPK (Nitrogen, Phosphorus and Potassium) mineral fertilizers due to its composition of essential macronutrients expresses strong influence on the good development of the plants, however, it has a fast leaching.Thus, the associated use of an organic and mineral source becomes one of the alternatives to increase the efficiency of the fertilizer (Oliveira Neto et al., 2017).
Few studies deal with organomineral fertilization for seedling production in cashew tree cultivation, mainly in relation to rootstock.In this sense, the objective of this study was to evaluate the effect of the application of increasing doses of organomineral material on the development of cashew rootstocks.

Material and Methods
The experiment was conducted from September to November 2017 in the experimental area of the Center of Science and Technology Agrifood of the Federal University of Campina Grande, Pombal-PB, whose reference coordinates are: latitude 6°46′12″ S, longitude 37°48′7″ W and 184 m of altitude at sea level.The city of Pombal is located in the semi-arid northeast of Brazil, according to the classification of Köppen (1948), the climate of the region is type hot and humid with average annual precipitation of 431.8 mm, with average temperature of 35±5 °C and mean relative humidity 40±15%.
The rootstocks produced in this assay resulted in native seeds, suplied from cashew producers of the Livramento Cariri and in the region.The seeds were initially subjected to the density test, and emerged for 24 hours in water to select those with higher density, eliminating the less dense floaters, considering the potential of lower germination.A sandy Franco texture soil was used, collected in the 0-30 cm depth range, on the Pombal-PB campus.The results of the soil analysis are shown in Table 1.Note.pH = pH of the substrate; CE = Electrical conductivity.
The fertilization was performed two days before planting, incorporated to the soil organic matter and mineral components, urea, triple superphosphate and potassium chloride, as Ximenes (1995), recommendations being the source of used organic matter the bovine manure, the analysis is in the Table 2.
Table 2.Chemical analysis of Bovine Spittle used in the experiment.Pombal-PB, 2017 Characteristics Chemicals Note.SB = sum of bases; EC = electrical conductivity; T = total cation exchange capacity; MO = organic matter.
The experiment was conducted in a randomized block design in factorial scheme 5 × 4, consisting of 5 levels of organic matter and 4 levels of mineral fertilization (NPK), repeated 4 times, and totaling 80 plants.The organic fertilizer was distributed in the proportion of 0, 10, 20, 30 and 40% of the weight of the substrate contained in the container, equivalent to 0, 100, 200, 300, and 400 g of bovine manure/1 kg of soil, respectively, since the mineral fertilization consisted of 0, 0.1, 0.2 and 0.3% of the weight of the substrate contained in the recipient, 1, 2 and 3 g of Nitrogen, Phosphorus and Potassium-NPK/1 kg of soil, using as urea source (44% N), triple superphosphate (41% P 2 O 5 and 12% Ca) and potassium chloride (60% K 2 O) in the proportion 10-20-30, respectively.
The siege was carried out directly in containers (bags of black polyethylene with dimensions of 20 cm wide by 35 cm in length), with capacity for 2 kg of substrate, bored laterally, being sown a single seed per container with the bas and turned up to a depth of 3.0 cm, as recommended by Barros et al. (1993).The experiment was conducted in a protected environment (greenhouse) for a period of 60 days after sowing.Cultural treatments were limited to irrigation and weed control, as no pest and disease attack was observed during experimental co-cultivation.
At 60 days after sowing, the following evaluations were performed: plant height (cm), (measured from the cervix to the apical bud); diameter of the stem (mm) (measured at a distance of 5.0 cm from the collar); number of leaves (number of leaves larger than 5.0 cm); and leaf area (cm 2 ) according to Equation 1: Where, L = leaf width; C = leaf length (Murthy et al., 1985).
The fresh masses (leaf, stem and shoot) were also checked in analytical balance.After that, the dry mass (leaf, stem and aerial part) was determined, with drying in forced air circulation at 65 °C, until constant mass, being expressed in g plant -1 .
Subsequently, the percentage of biomass (PB) was calculated according to the Emon et al. (2015) method, expressed by Equation 2: Where, MST = total dry mass of the plant and MFT = total fresh mass of the plant.
It was also calculated the quality index of seedlings according to Dickson et al. (1960) using the dry mass of shoot and root, total dry mass, height and diameter of seedlings, according to Equation 3: Where, MST = total dry mass (g); H = height (cm); DC = lap diameter (cm); MSPA = shoot dry mass (g); MSRA = root dry mass (g).
The data referring to the variables measured were subjected to the F test at 0.05% significance by means of analysis of variance and the means of the variables were submitted to regression analysis.For the accomplishment of the statistical tests, the available resources were utilized in the Computational System of Statistical Analysis-SISVAR 5.6 (Ferreira, 2011).

Results and discussion
Cashew tree seedlings at 60 days after sowing had a significant interactive effect at 1% probability (p ≤ 0.01 and ≤ 0.05) for all variables analyzed, demonstrating that both organic and mineral fertilization interfered in the development and qualities of the seedlings, except in the stem diameter that meant only for the organic input (Table 3).4B).Results similar to this work were observed by Serrano et al. (2013) evaluating the production of 'CCP 06' cashew rootstocks verified that high doses of NPK caused a reduction in the values of dry mass accumulated by the plant.
The percentage of biomass (PB) in the absence of NPK was adjusted to the quadratic model with maximum point at 308 g of manure with PB of 32.68%, declining from that dose (Figure 4C).Furthermore, it was verified that 1 g of NPK provided a greater accumulation of biomass, since it obtained 37% of biomass in the estimated dose of 300 g, whereas the dose of 2 g of NPK reached 33% when associated with 249 g of manure bovine.However, the dose of 3 g of NPK was adjusted by a linear regressive model, equipotente to 24.35% reduction with increase of the organic input.
The excess of the organic input supposedly may have caused inhibition of some essential nutrients, according to Costa et al. (2012), found that the levels of Zn (zinc) and S (sulfur) increased dramatically with increasing percentages of the organic compound causing phytotoxicity.These authors further conclude that the use of 20% of the compound is sufficient for seedling production, as well as in this work.
Dickson Quality Index (DCI) is an important variable for diagnostic air quality seedlings for allies the and the equilibrium distribution of biomass as a correlation result of various morphological import before (Prates et al., 2012).Thus, it was observed that the dosage of 1 g of NPK with 200 g of manure obtained IQD of 1.28, while the use of 2 g of NPK provided in association with 200 g of manure had IQD of 1.1 and the absence of NPK at the dose of 280 g of manure received 0.90 IQD.Corroborating with the other growth variables, the dose of 3 g of NPK under these conditions decreased 38.86% the quality of the seedlings as the doses of manure increased, probably due to this dosage of the mineral fertilizer causing phytotoxicity.
Considering the exposed, it is assumed that the best combination for production of cashew tree seedlings was obtained using the dose of 1 g of NPK conciled with 200 g of bovine manure, because, as affirm Freitas et al. (2017) the higher the quality index of the more standardized seedlings these are.The reduction will be observed in the quality of seedlings from 300 g manure and NPK 3 g dose is due to the excess salts from both the manure as fertilizer, these respective concentrations, similar results were found by Oliveira et al. (2015) when studying guava rootstocks under different sources and proportions of organic materials, which observed higher quality of seedlings in the proportion of 40% of the organic material declining with increasing proportion.

Conclusions
Under the conditions of this work, bovine manure provided an improvement in the growth of the rootstocks, but their excess may damage the cashew tree seedlings; The use of NPK fertilizer promoted increase in the development of the seedlings, however the use of 3 g of NPK was not satisfactory causing phytotoxicity; The organic and mineral combination (1 g of NPK and 200 g of bovine manure) provided the largest increases in vegetative growth and shoot quality characteristics in the cashew tree.

Table 1 .
Physical and chemical characteristics of the soil used in the experiment, Pombal-PB, 2017