Morphometry of Tabebuia aurea (Manso) Benth. & Hook. f. ex S. Moore subjected to different substrates

The morphometry and quality of seedlings of tree species is of fundamental importance to achieve success in reforestation or commercial exploitation project. Due to the lack of information about the ideal substrate for the production of craibeira seedlings and taking into account the diversification of the use of Tabebuia aurea production of native seedlings for the recovery of degraded areas, this work was conducted with the objective of evaluating the development of seedlings of this species produced with bovine manure and coconut fiber. The present work was carried out at the plant ecophysiology laboratory at the Agrarian Engineering and Sciences Campus (CECA), in Rio Largo, north-region of the state of Alagoas. Four treatments were used, which consisted of a mixture of soil + organic material, in the proportion 3:1. The materials used were tanned bovine manure (ESCB), coconut fiber (CFS) and control (soil). Whose proportions of the treatments were: T1: soil + 0% coconut fiber; T2: soil + 11% coconut fiber; T3: soil + 22% coconut fiber; T4: soil + 33% coconut fiber and T5: soil + 33% cattle manure. Macro and micronutrient analyses of the substrates used were performed. To meet the work objective, the following parameters were evaluated: plant height, stem diameter, number of leaves and leaf dry matter, stem and root and chlorophyll content index. It can be concluded that the substrates chosen for evaluation showed few significant differences in relation to seedling development; the mixture of treatment 2 (soil+coconut fiber 11%) provided a higher percentage of survival and the quality of seedlings were higher; The substrate treatment 4 (soil+coconut fiber 33%) showed much lower results in all evaluated results. However, statistically there were no significant differences in relation to the other treatments and the presence of bovine manure (soil+bovine manure 33%) results in benefits such as greater nutrient supply and possible reduction of seedling costs.


INTRODUCTION
The demand for seedlings of native forest species has increased every year, mainly due to the need to reforest or remake degraded areas, aiming to minimize environmental impacts and biodiversity maintenance (FERNANDES et al., 2000).
To adequately meet this demand, there is a need to produce good quality seedlings, since the success of a planting depends directly on the genetic potentialof the seeds and the quality of the seedlings produced (SANTOS et al., 2000). Among the factors that influence seedling production, the substrate plays a fundamental role, as it is the environment in which the roots develop, supporting and providing water, oxygen and nutrients to the plants .
The fiber of the green coconut shell, which has not yet been widely used, may become an important raw material in the production of good quality substrates for seedling production or in crops without the use of soil. In this 21 case, the use of green coconut shell is feasible because its fibers are almost inert and have high porosity. The ease of production, low cost and high availability are other additional advantages presented by this type of substrate (CARRIJO et al., 2002). It is a substrate of easy handling, with good water absorption capacity, does not require daily reumding and provides good germination performance of seeds (FAVALESSA, 2011, p 21).
Another extremely important substrate for seedling production is bovine manure is a large organic source used in the composition of substrate for seedling production (ANDRADE NETO et al., 1999). Organic fertilization with bovine manure, in addition to improving drainage and substrate aeration, increases water storage capacity, nutrient levels and the population of microorganisms beneficial to the substrate and plant, stimulating root development (MALAVOLTA et al., 2002).
Due to the lack of information about the ideal substrate for the production of craibeira seedlings and taking into account the diversification of the use of Tabebuia aurea production of native seedlings for the recovery of degraded areas, this work was conducted with the objective of evaluating the development of seedlings of this species produced with bovine manure and coconut fiber.
Based on the premise that based on the literature the substrates used in this experiment act as promoters of plant development, it is expected that the treatment with the coconut fiber substrate will present better development, since this substrate presents good moisture retention, release of nutrients such as sodium and good aggregation.

Study site
The present work was carried out at the facilities of the Laboratory of Plant Ecophysiology of the Center for Agrarian Sciences (Ceca), in Rio Largo, north region of the state of Alagoas, located at 9° 28'02' latitude and 35°49'65' longitude with an altitude of 135m, the average annual precipitation is 1200 to 1800 mm and relative humidity ranging from 76 to 90% with minimum annual average temperature and 20° and maximum of 29°. The work was developed from June to August 2019 and kept on screen during the development and evaluation period.

Soil collection, substrate preparation and seeds
The seeds, from trees growing in The UFAL, Campus A.C Simões, being removed the side wings and selected for size and color. Then, the sandy latosol was collected from the laboratory of Plant Ecophysiology was sifted, placed in bags, labeled and taken to be made physiochemical analyses in the Soil Laboratory in the Center of Agrarian Sciences.
According to the results of this analysis contained in Table 1.  The analysis indicates a clayey sandy soil with low Ca, Mg and pH contents, favoring the availability of exchangeable aluminum, thus lowering the availability of phosphorous, forming aluminum phosphate. Therefore, the introduction of substrates rich in plant-essential macronutrients help in the correction of soils with nutritional deficiencies.

Sowing
Sowing was carried out by placing three seeds per three-liter plastic bag. Thirteen days after emergence, the seedlings with minor developments were thinning, using scissors for cutting, with only one seedling per plastic bag remaining, as shown in Figure   1. The moisture of the experiment was maintained with watering in an interval of two days.  Dry matter (Root, Leaf and Stem): Plants will be fractionated in part aerial (stem, leaves) and roots. Then the material will be placed to dry separately in a forced air circulation oven, at a temperature of 65ºC until it reaches constant weight, which will occur after 48 hours, and then weighed in analytical balance.
 Chlorophyll content index (Spad Index): Chlorophyll content index will be determined every three days by non-destructive method using chlorophyllmeter (SPAD-502 -Minolta, Japan). Ten random readings will be performed on one leaf each plant and with the average of these values will be obtained the final value of the SPAD index.

Experimental Design
The experimental design was used in randomized blocks, in factorial scheme 5 (substrates) x 1 (container size), totaling five treatments, with 5 replications, and 25 plants per plot. Isolated effects were determined.
To verify if the coconut fiber varies in the treatments, first the normality test of the data will be performed, if they present normal distribution will be analyzed by the parametric test and the data obtained will be submitted to variance analysis at 5% probability by the F test, and the means of the treatments are compared by the Tukey test.
The Statistical Program Sisvar will be used for the analyses.

RESULTS
All morphological characteristics did not present statistical differences when compared between treatments ( Table 1).

Number of leaves
As for the number of leaves, there was a variation in plant development in all treatments, the leaf count is based on the emergence of the true leaves, obtaining an amplitude of 2 to 10. Thus, the highest mean occurred in the T5 treatment (soil + 33% cattle manure), when compared to the other treatments, as shown in Figure 2.

Stem diameter
Based on the statistical analysis, for the variable stem diameter, it was observed that the T5 treatment (soil + 33% cattle manure) presented higher values, whose variation was from 1.45 to 3.76 mm, but there was no significant difference when compared to the other treatments (Figure 3).

Relative Chlorophyll Content
The summary of the mean values of the analysis of variance for relative chlorophyll content (SPAD Index) is represented in Table 3, where there was no statistical difference. Analyzing Figure 4, it is observed that the highest meanSPad Index is represented in the T2 treatment (soil + 11% coconut fiber), whose mean value was 39.42, not differing statistically from the other treatments. Treatments T1, T3, T4 and T5 showed a reduction of 20.53%, 7.21%, 43.20% and 34.36%, respectively, and these treatments were the lowest mean values of the SPAD Index. Regarding the variable dry mass of the leaf, the highest values were obtained were the T2 treatment (soil + 11% coconut fiber), with an average value of 0.674g. The treatments T1 (soil + 0% coconut fiber), T3 (soil + 22% coconut fiber), T4 (soil + 33% coconut fiber) and T5 (soil + 33% cattle manure) showed the lowest mean values of dry mass of the leaf ranging from 0.470 to 0.602g of leaves, as shown in figure 5.

DISCUSSION
Regarding the height at 62 days, there was greater growth in the seedlings produced in treatment 2 (soil + 11% coconut fiber), According to Wendling and Gatto (2002)  In addition, the spad chlorophyll content index is quite feasible, as it is a nondestructive method that does not require the use of chemical reagents for analysis (DIDONET et al., 2005), which facilitates the management of seedlings in nurseries. Oliveira and Perez (2012) observed in Tabebuia aurea that the highest shoot dry matter values were obtained when the plants were grown at higher light intensities and, as the cultivation time increased, there was a greater difference in growth, with lower carbohydrate accumulation in more shaded environments. The best averages were treatments 2 and 5, where T2 obtained better results, with little significant difference between them, treatment 4 stood out for the lowest mean.