Biological Fertilization as an Attenuation of Salinity Water on Beetroot ( Beta vulgaris )

Salinity is one of the major obstacles of modern agriculture, especially in the semi-arid regions, since these have high rates of evaporation and water sources with high salt terrors. Thus, the present study aimed to investigate the attenuating effects of bovine biofertilizer and biological fertilizer under irrigation with saline waters on the morphological behavior of beetroots (Beta vulgaris L.). The design was randomized blocks in a factorial scheme 4 × 2 + 1, referring to the electrical conductivity of the irrigation water (ECw: 0.5, 1.5, 3.0 and 6.0 dS m) and application of bovine biofertilizer in the absence (BIO I), and presence of Microgeo (BIO II) and a control (without fertilization and ECw 0.5 dS m). No effects of the factors evaluated on the gas exchange of beetroots were observed. However, the increase of ECw has negative effects on phytomass and growth of this crop, as the application of bio fertilizer favors some soil chemical characteristics.


Introduction
Semi-arid regions, characterized by high evaporation rate of the water slides, poor soil drainage, are compelled to use the irrigation, making them productive, because of which they are susceptible to salinization (Pedrotti et al., 2015).In the Brazilian semi-arid region, the water quality oscillates at certain times of the year, as well as in the geographic positioning, in relation to the arid zone.
Among beetroot (Beta vulgaris L.) is an alternative, since it presents threshold salinity values of 7.0 dS m -1 , classified as moderately tolerant to excess salts in advanced stages of growth (Deuner et al., 2011).This behavior expresses the ability of osmotic adjustment, presented by the beetroot.
In Brazil, beetroot, is one of the most ten vegetables grown and consumed (Marcolini et al., 2010).It is a nutritional demanding crop, requiring fertilization program capable of supplying its consumption requirement in the crop.It has productivity, between 20 and 35 tons per hectare (Filgueira, 2012).
In this perspective, Silva et al. (2013), Santos et al. (2016), Paiva et al. (2017), highlighted the favorable yield of this crop, under salinity conditions, and it can be an income alternative to semi-arid rural producers.It is very important to emphasize that the increase of organic and inorganic solutes inside the plants, the interaction between salinity and fertility, had shown a significant effect on the effects of degenerative effects of saline stress promoted by irrigation water on crops (Willadino & Camara, 2010).Sousa et al. (2017) working with sesame (Sensamun indicum L.); Sousa et al. (2012) studying peanut (Arachis hypogaea L.), found that the bovine biofertilizer reduced the depressive effect of salinity on morphophysiological aspects of these cultures.In view this, the aim of this study was to investigate attenuating effects of bovine biofertilizer and biological fertilizer under irrigation with saline waters in the morphological behavior of beetroot.

Material and Methods
The experiment was carried out in a protected environment of the Agricultural Sector of the Center for Social and Agrarian Human Sciences (CCHSA), Federal University of Paraíba (UFPB), Bananeiras, PB.The used soil on this study was classified as a typical Psamitic Regolitical Neosoil, from which a composite sample had collected for physical and fertility analysis (Table 1) in the CCHSA Soil Laboratory.The chemical analysis of used water (Table 2) had carried out at the Soil Laboratory of the Agricultural Sciences Center at UFPB, Areia, PB.The increasing conductivity doses (1.5, 3.0, 4.5 and 6.0 dS m -1 ) had prepared using a portable conductivity meter, using a control water of weir (0.5 dS m -1 ), belonging to the experiment site.The evaluated treatments were biofertilizer without Microgeo ® (BIO I), prepared in the proportion 1:1, produced by aerobic and biofertilizer process with Microgeo ® (BIO II), prepared using the same process mentioned above.
However, the last one had produced with 15% bovine manure, 5% Microgeo ® and completing with 80% water (0.5 dS m -1 ).These fertilizer had conditioned in plastic containers with 100 dm 3 capacity, uncovered, guaranteeing the continuous process of aerobic fermentation (Table 3).
Seeds used were the Earley Wonder (Isla ® ) variety.Seeds had sown in 150 ml pots and at 15 days after planting (DAP), they had transplanted to polyethylene pots with a capacity of 5 dm -3 .After transplanting, the seedlings received the biofertilizer treatments (with and without Microgeo ® ), using 300 mL of biofertilizer without Microgeo ® (BIO I), at 1:10 dilution, according to recommendations of Silva et al. (2007) and the same volume of biofertilizer with Microgeo ® (without dilution) (BIO II).
Saline water treatments started at 8 DAP, 300 mL of water had administered by hand irrigation.The experimental units received weekly scarification in order to combat soil compaction.At 20 DAP the presence of ceroscopies (Cercospora beticola) had diagnosed, being controlled with the application of bordeaux broth.
The experimental design was a randomized complete block (DBC), with three replications, in a factorial scheme 4 × 2 + 1, referring to 4 electrical conductivities of irrigation water (0.5, 1.5, 3.0 and 6.0 dS m -1 ) in soil treated with biofertilizer without Microgeo ® (Bio I) and biofertilizer with Microgeo ® (Bio II), and a control treatment, that is, without any of the organic inputs under irrigation with water of lower salt content (5 dS m -1 ).
Morphological, chlorophyll and gas exchange analyzes were performed at 15, 30, 45 days after transplanting (DAT).Chlorophyll a, b and total indexes (FCI) had determined with the aid of an electronic chlorophyll meter (Clorofilog ® CFL1030, Falker), making three readings in each plot, selecting leaves from the middle third of the plant to obtain an average corresponding to the respective treatment (Silva et al., 2015).The gas exchange measurements had performed in the morning using an IRGA (ACD, LCPro-SD, Hoddesdon, UK) infrared gas analyzer with 300 mL min -1 air flow and coupled light source of 1200 μmol m -2 s -1 .Where the net assimilation rate of CO 2 (A), intercellular CO 2 concentration (Ci), stomatal conductance (gs), transpiration rate (E) and instantaneous carboxylation efficiency (EiC) had evaluated.
At 75 DAT the length of the shoot (cm), plant height (cm), number of leaves, bulb diameter (mm), root length (cm) and fresh root, shoot and bulb mass (g).Dry matter mass of the aerial part and root (g) had determined after the fresh matter remained in the circulation oven for approximately 48 hours at a temperature of 65 C until constant weight had obtained, using a precision scale (0.001 g) for calibration.At the end of the experiment, soil samples had collected for fertility analysis.Data had submitted to analysis of variance and regression using the statistical program SAS University Edition (Cody, 2015).

Results and Discussion
The leaf length at 45 days after transplanting (DAT) showed a significant effect for the isolated effect of the electrical conductivity of irrigation water (Figure 1), since plant height and leaf width did not show in any of the evaluation periods (15,30 and 45 DAT).No significant interaction had also noted between the factors.This situation differs from Silva et al. (2015) who concluded that water salinity and fertirrigation management interfere with growth, emphasizing the depreciation of the Early Wonder cultivar, in detriment to the osmotic adjustment in relation to Itapuã.As ECw was increased, it had noted that there was a decrease on leaf length of beetroot (Figure 1).The same had observed by Santos et al. (2016), which obtained a decrease in the morphophysiological aspects of this culture under ECw of 2.85 dS m -1 .This behavior had related to the fact that moderately salinity tolerant plants, such as beetroots, suffer from water restriction due to salinity increase, reducing the osmotic potential of soil solution, reducing water absorption capacity, resulting in morphological changes, losses of metabolic and physiological activities (Willadino & Camara 2010).
Among all the variables evaluated at 75 DAT (shoot length, plant height, leaf number, bulb diameter, root length and fresh root, shoot and bulb mass), only the fresh shoot mass (FSM) showed interaction among the evaluated factors (Figure 2).At 15 DAT, it had observed that the stomatal conductance (gs) showed a higher average value in the ECw of 6 dS m -1 , the same observed for the rate of assimilation of CO 2 (A), water use efficiency (WUE) and instant water use efficiency (iWUE).It can be linked to acclimatization, in terms of gas exchange, to the stress to which the plant is subjected.Although at 45 DAT, it had observed that as ECw increased, there was a decrease in gs, A, E, WUE, iWUE and EiC.As a means of alleviating the stress effect, the plant can close its stomata, reducing water absorption and consequently the entrance of toxic salts.Closure of the stomata may result in a decreased transpiration, and internal CO 2 concentration in leaves (Dalastra et al., 2014).Therefore, plant diminishes its photosynthetic processes, the fixation of CO 2 and the production of photoassimilates.
Table 5. Mean values of stomatal conductance (gs) (mol H 2 O m -2 s -1 ), assimilation rate of CO 2 (A) (μmol CO 2 m -2 s -1 ), internal carbon concentration (Ci) (μmol CO 2 m -2 s -1 ), water use efficiency (WUE) (A/E), instantaneous water use efficiency (iWUE) (A/gs), instantaneous carboxylation efficiency (EiC) (A/Ci), vapor pressure deficit (DPV) and foliar temperature (Tleaf) (°C) of beetroot (Beta vulgaris) in functioning to the application of different biofertilizers at 15, 30 and 45 days after transplanting (DAT)  org contents in so n.However, it n of the biofer , due to the na gure 1A).ase of ECw, ob ffer statistically Figure 4B).M ium soil and F er via soil, inc acidity levels i ol (Figure 4C).The organic matter content obtained an optimum point in relation to ECw of 1.5 dS m -1 , decreasing again, after increasing ECw on soil solution (Figure 5A).Bellini et al. (2013) verified similar results, reporting that the biofertilizer influenced soil fertility and maintained a tendency to reduce organic matter levels.Content of phosphorus (P) was higher in ECw 3 dS m -1 decreasing again after elevation (Figure 5B).Ferreira et al. (2007) verified the increase in the nutrient content on soil after saline application and emphasize that it is related to the ionic strength or nutritional disorder induced by high levels of chlorine in the plant tissues, inhibiting the absorption of P. In addition, because the reduction of P content on soil is due to a bigger absorption by the plant to perform its metabolic activities in the face of salt stress.
Magnesium content on soil had linearly inhibited because of increased ECw (Figure 5C).According to Garcia et al. (2007), the Na + /Ca 2+ and Na + /Mg 2+ ratios are directly proportional to the absorption of sodium in detriment of the calcium and magnesium absorption by the plant.However, the reduction in Mg 2+ content can be attributed to water percolation due to salinity and consequently low soil permeability (Dias et al., 2010).The values of the sum of bases obtained a linear increase as a function of the increase of ECw (Figure 5D).Biofertilizers showed isolated effects for phosphorus, calcium, magnesium, base saturation and organic matter content in soil solution (Table 6).
The application of Microgeo ® showed a difference related to the non-application of this input for phosphorus (P), magnesium (Mg 2+ ) and organic matter (OM), but did not differ from the control.Calcium content (Ca 2+ ) did not show differences in the application or not of Microgeo ® , since for the saturation of bases (V) the application showed differences, being the absence, which obtained a better result.

Conclusions
The increase in the electrical conductivity of the irrigation water (ECw) affects leaf length, fresh shoot mass, diameter and fresh mass of beetroot bulb; ECw, neither by the application of biofertilizers, does not influence gas exchanges.Biofertilizers have attenuated the effects of ECw in potassium, sodium, potential acidity, sulfur and cation exchange capacity on soil solution.ECw has an isolated effect on levels of phosphorus, magnesium, organic matter and sum of bases; biofertilizers have an isolated effect on phosphorus, calcium, magnesium, base saturation and organic matter levels.It implies that the increase of ECw has a negative effect on beetroot growth and phytomass, and the application of biofertilizers favors some chemical soil characteristics.

Figure 1 .
Figure 1.Leaf length (CF) of beetroot (Beta vulgaris) at 45 days (DAP) as a function of salinity of the electrical conductivity of irrigation water (ECw) Figure 2. I Figure 5.

Table 1 .
Chemical and substrate texture analyzes

Table 2 .
Analysis and classification of salinity water levels