Initial development of Dipteryx alata Vog consortium with cover plants

Cover plants, due to their high biomass production capacity, and plants provide the soil with several benefits such as nutrient cycling, greater water retention and storage capacity, reduced temperature, increased aggregation and microbiota, physical protection against compaction. The objective of this work was to verify the growth of the fruit species of the cerrado, Dipteryx alata Vogel, as a consortium strategy with green fertilizers, Arachis pintoi Krapov. & W.C.Greg./Callopogonium mucunoides Desv., Crotalaria juncea L, Dolichos lablab L., [Urochloa decumbens (Stapf) R.D.Webster] with nitrogen and [Urochloa decumbens (Stapf) R.D.Webster] without nitrogen (control). The experiment covered the period from 2013 to 2017, in Rio Verde, Goiás, installed in a randomized block design, with five treatments (cover plants) and four replications. The evaluations included the macro and micronutrient contents in D. alata, biomass production by cover plants, soil moisture and biometric determinations of D. alata. The use of U. decumbens with nitrogen, D. lablab and C. juncea showed better performances in maintaining soil moisture, growth and early fruiting of D. alata, making it advantageous to use these types of consortium in its establishment under conditions of the Cerrado.


Introduction
The Cerrado is a biome with rich biodiversity, accounting for around 11,000 cataloged plant species, many endemic to the region, being recognized as the richest savanna in the world (MMA, 2014). Natural environment for approximately 4,440 plant species and considered one of the 25 global critical points of biodiversity (de Carvalho Mendes et al., 2012). However, the distribution of the remaining natural areas is highly asymmetric in relation to the Cerrado physiognomies.
In the Cerrado the native fruit plants are evident, being a group that adds up to more than 50 species, even in their natural state, they demonstrate adaptability in agricultural system and representative productivity (Andaló et al., 2018;Soares et al., 2018). The most explored potential of the Cerrado is the fruits, in which is consumed naturally or in the form of juices, liqueurs, jellies and savory dishes (de Andrade Silva & Fonseca, 2016;Donado-Pestana et al., 2018;Franco et al., 2020). The fruits are rich in nutrients, such as minerals, vitamins, amino acids, proteins, carbohydrates and oils. The varied shapes, flavors, aromas and colors represent another important characteristic of the Cerrado fruits (Coradin et al., 2011).
Fruit species found in this Biome are useful for economic use, such as the fruits of Hancornia speciosa Gomes, Bromelia goyazensis Mez, Mauritia flexuosa L.f., Alibertia edulis (Rich.) A.Rich., Byrsonima crassifolia (L.) Kunth, among others (de Andrade Silva & Fonseca, 2016;Oliveira et al., 2012;Schiassi et al., 2018). Among other species, Dipteryx alata Vog. Stands out, popularly known as "baruzeiro", in addition to other names. It is an imposing tree in the Cerrado due to the large size of the stem and crown, in addition to its environmental importance in biological nitrogen fixation, food for fruit productivity, pharmacological due to its curative and wood properties due to its quality and density, it can be used in various types of construction (Carrazza & Ávila, 2010).
Integrated cultivation with cover crops in fruit growing is already widely used. Cover crops contribute to sustainable agricultural exploitation with several benefits to the soil and the crop of interest. It is a conservationist practice that aims to improve soil fertility, by maintaining the biomass produced (López-Bellido et al., 2004;Thorup-Kristensen et al., 2003). They assist in soil porosity, water infiltration, nutrient replacement, invasive weed control, with consequent productivity gains in agricultural crops (N. Garcia-Franco et al., 2015;Paulo et al., 2016). The maintenance of cultural remains on the soil surface has been used as an alternative to reduce variations in soil temperature, reduce erosion losses, retain more water and promote higher yields of agricultural crops, in addition to reducing water evaporation, runoff and increased infiltration rate (Gupta et al., 2015;Scopel et al., 2013). Cover plants release nutrients, organic acids, amino acids and phytohormones during their decomposition, which can favor intercropped plants (Delarmelinda et al., 2010;Paulo et al., 2016;Schroth et al., 1992). This practice increases the soil's organic matter (Noelia Garcia-Franco et al., 2018) and reduces environmental impacts of the main crop (Nemecek et al., 2015). Provides improvements in various soil attributes and biological nitrogen fixation, nutrient cycling, moisture maintenance, less thermal amplitude of the soil, making the activity of beneficial microorganisms in the soil favorable (Chapin et al., 2011;Corrêa et al., 2014;Júnior de Almeida et al., 2015).
Nevertheless, some specific care is needed regarding the choice of cover plants to be used, as well as species that are of time and growth habit consistent with the management of the fruit tree of economic interest, as well as other effects of coexistence, minimizing the risks of competition (Aguilar-Fenollosa & Jacas, 2013; Korte & Porembski, 2010;Norgrove & Hauser, 2013;Perin et al., 2009). Studies using native fruit trees from the cerrado submitted to the consortium with cover plants are scarce in the literature. Thus, the objective was to evaluate the responses provided by the consortium of D. alata with perennial and annual cover plants, in the production of plant biomass, maintenance of soil moisture and effects on the growth and absorption of nutrients from the fruit tree.

Methodology
The experiment was implemented in the field in December 2013, and the results of this study cover a period of 4 agricultural years (2014 to 2017). Held in an area of Dystroferric Red Latosol, at the Federal Institute of Goiás -Campus Rio Verde, southwest region of the State of Goiás. Located at 17º 48' 46" S and 50º 54' 02" W and altitude of 693 m. The climate is classified, in the Köppen climatic categories, as Aw, with two defined seasons, with dry winter (from April to September) and hot and humid summer (from October to March), average annual temperature and precipitation of 23.3ºC and 1,663 mm, respectively.
The experimental design adopted was in randomized blocks (RBD), with five treatments, which represent the five (control), with four repetitions. All treatments were combined with D. alata. Before the implementation of the experiment, the area was pasture, formed by U. decumbens, and then the sowing of this cover plant was dispensed with. The other annual cover plants (C. juncea and D. lablab) were sown annually, in the month of November of each year (rainy season). The treatment formed by the perennial cover plant was initially established by A. pintoi. However, this species showed incompatibility with the dry climate of the region and, after completing 2 years of experiment, it was replaced by C. mucunoides. D. alata seedlings were distributed 5x5 m between rows and between plants in pits with dimensions of 40x40x40 cm, in December 2013. Quantitative measures (biometric) were evalueted in December of each year, with the aid of a ruler, tape measure and topography sight. The height was measured, measuring from the ground to the largest end of the branch. For the stem diameter, a digital caliper 5 cm from the ground was used. Annually at 150 days after the sowing of the cover plants, for the purpose of assessing biomass production, he used a metal frame of 1 m², launching randomly in each treatment, being cut the vegetable mass contained inside. These samples were weighed while still green and stored in a forced air circulation oven at 65º C, for at least 72 hours, to obtain dry matter.
After sampling, the cover plants were mowed with the aid of a tractor and brush cutter, except for A. pintoi and C. mucunoides, as they are small cover plants. Covering fertilization was carried out on the U. decumbens + N plot with 220 g of urea/plant in the crown region, in three stages in the months of November, February and April of each year, equivalent to an annual nitrogen fertilization of 40 kg ha-1. Annually, after the end of the rainy season (April to September), soil sampling was carried out to determine moisture levels by the gravimetric method, in the 0-5 cm layer. Then, the samples were taken to the Research, Society and Development, v. 10, n. 3, e55810313673, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i3.13673 4 laboratory to determine the wet weight, where they were stored in a forced circulation oven at a temperature of 105ºC for 24 h, weighed to obtain the dry weight according to the methodology described by Apha (2005), with the formula% Humidity = WW-DW/PUx100, in which: WW = Wet weight of the sample (g); DW = Dry weight of the sample (g). In June, developed leaves of D. alata were collected, then washed in distilled water, dried in an oven at 65ºC until constant mass. They were ground in a Willey mill, to analyze the levels of nutrients present in the plant tissue, according to the methodology described (Malavolta et al., 1997).
To describe the growth curve of height and diameter as a function of days, the Exponential model Yi = A ekXi+ei, was used, where: Yi is the height or diameter of the plant on day Xi; represents the estimate of the initial value (height or diameter); k is the specific growth rate; ei the error associated with each observation which, by presupposition, is NID (∑2).
The structure of variance and covariance of errors between the evaluations was verified. To estimate the parameters, the least squares method and the Gauss-Newton algorithm were used. The methodology presented by (Regazzi & Silva, 2010) was also used to test the identity of nonlinear regression models and the equality of any subset of parameters, using the likelihood ratio test, with the likelihood ratio test, with chi square approximation, at 5% significance. To perform the likelihood ratio test, an indicator variable (dummy) was created for the representation of the models, which assumes binary values 0 or 1; thus, the complete model, with different parameters for the five types of consortia.
The data were submitted to the Shapiro-Wilk normality test, and homogeneity of variances by the Bartlett test, both at 5% probability. Due to the lack of conformity, non-parametric analysis was performed using the Kruskall-Wallis test, followed by the analysis of main components, and cluster that describes multivariate statistical procedure, serving to identify homogeneous groups in the data, based on variables, allowing the observation of similarities (Landim, 2011). The correlations of the variables were assessed by Pearson's correlation test, studied by (Schuberth et al., 2018) at 5% probability. For all statistical analyzes performed in this experiment, the statistical program SAS, version 9.2, was used (SAS Institute, Cary, North Carolina, EUA).

Results and Discussion
The best model to explain growth was that with different initial values between plants, and an equal growth rate (Table 1). When observing the confidence interval of parameter A for height, it was found that the cover plants D. lablab and U. decumbens + N, showed higher value than the plant U. decumbens (Table 2). As for the diameter of the plants, it was observed that the U. decumbens plant had a lower value, where the others differed from each other. A. pintoi /C. mucunoides, also did not differ between themselves and with the other plants (Table 2). Plants grown in consortium with A. pintoi /C. mucunoides, had smaller stem diameter. The other cover crops had no effect on the stem diameter of D. alata.     Table 2). It is worth mentioning that C. mucunoides is a perennial fabacea, unlike the others, which are annual. This characteristic causes the plant to present, in its initial establishment, a lower growth rate, bringing less benefits to the environment to which it is inserted. It is believed that the result will be significant in the long term, after its full establishment, where the soil will not be uncovered, thus avoiding the luminous incidence, inhibiting the emergence and the development of weeds (Teodoro et al., 2011). It is important to note that C. mucunoides also incorporates into the soil, a substantial amount of nitrogen, from the biological nitrogen fixation process (Moreira et al., 2014).
In 2014, D. alata plants exhibited greater heights and diameter with coverage of U. decumbens + N. The areas with D.
lablab provided the plants with higher production of fresh matter (MF) and dry matter (MS), with soils with higher humidity.
Consortia with C. juncea, U. decumbens and C. mucunoides did not stand out (Figure 2). Similar behavior was observed in other studies (Carlos et al., 2014;de Moraes Sá et al., 2015). In 2015, the two main components explained approximately 70% of the variation captured by the variables. There was a low correlation of Fe, MF and MS with other variables. The U.
decumbens + N consortium provided higher leaf contents of Mg, Mn, Ca in D. alata plants; greater MS and MF materials and greater heights. Such behavior, also, was identified in other works with D. alata (Machado et al., 2014). The consortia of D.
alata with C. juncea or with D. lablab had a positive impact on the leaf contents of Zn, Cu and N and on the stem diameter of the plants (Figure 3). Studies with nitrogen fertilizers in cover crops can be seen in (Kandel et al., 2018;Portugal et al., 2018).   Nitrogen fertilization has shown satisfactory results (Ebúrneo et al., 2018;Portugal et al., 2018). There is a fundamental role of K in the growth and development of plants (Ruthrof et al., 2018;Tighe-Neira et al., 2018).    The results of the evaluation of the variables in relation to the grouping show that there was no clear segregation in the variables when compared to the distribution. In general, according to the cluster analysis ( Figure 6), there was a grouping between all the consortium combinations for the years 2014 to 2017. However, in 2017, it was found that the consortium of D.
alata plants with U. decumbens + N differed from the others, characterized by the dominance among cover plants consortia, highlighting nitrogen fertilization. U. decumbens + N, D. lablab and C. juncea were the treatments that provided the best performance in the development of D. alata. It is worth mentioning that, in the case of D. lablab and C. juncea, they are cover plants that did not have the insertion of chemical fertilizers, thus providing the practice of sustainable use of the Cerrado soil.
Practices such as crop rotation can improve soil quality and, consequently, increase production rates, both in organic and conventional systems (Bai et al., 2018).

Conclusion
Although they have less capacity to maintain humidity levels, U. decumbens + N, C. juncea, D. lablab and C.
mucunoides were the cover plants that conferred the highest nitrogen content in D. alata. C. mucunoides produced the lowest amount of biomass, however it provided the lowest moisture losses in 2015 and 2017. Among the studied consortia U.
decumbens + N, D. lablab and C. juncea, were the treatments that provided the best performance in the development of D.
alata. Thus, further studies on D. alata discharged in consortium with more varieties of cover plants should be carried out, in order to contribute to the understanding of the interaction between these plants.