Seeds of Calotropis procera Treated With Essential Oils of Copaifera langsdorffii Desf . and Syzygium aromaticum L .

The Silk Flower (Calotropis procera) is widely used by farmers in the Northeast region, due to the adaptation of the climatic and soil conditions of the semi-arid region, but the incidence of pathogens has reduced the physiological and sanitary quality standards acceptable for sexual propagation of these plants in the field. Thus, the objective of this research was to verify the effects of the Copaíba (C. langsdorffii) and Cravo (S. aromaticum) oils on the health and physiological quality of silk flower seeds (C. procera) harvested in the city of Tacima, PB. The treatments were constituted by Copaíba (C. langsdorffii) and Cravo (S. aromaticum) essential oils at concentrations of 0.5; 1; 1.5; 2% and the fungicide Captan® (240 g, i.a. 100 kg seed). The control 0 (zero) corresponded only to the immersion of the seeds in distilled and sterilized water (ADE). In the evaluation of sanity, the method of incubation on filter paper (Blotter test) was performed, using twenty replicates of 10 seeds for each treatment. The physiological quality was evaluated by the germination test (G%), first germination count (FGC), germination speed index (GSI) and seedling dry mass (SDM). A microflora composed mainly of Alternaria sp. (52%), Fusarium sp. (70%), Helminthosporium sp. (40%), Cladosporium sp. (50%), Curvularia sp. (20%) and Nigrospora sp. (5%). The essential oils considerably reduced the percentage of fungi associated with silk flower seeds, but there was moderate phytotoxic effect under the germination and vigor of C. procera seeds.


Introduction
The Caatinga Biome has great economic potential still unexplored with a diverse native and exotic vegetation.Knowledge about the potentialities of caatinga species is necessary for the preservation of plant genetic resources, and the sustainability of the population that seeks food and income sources in this region (Oliveira et al., 2011).Among these species, the silk flower (Calotropis procera (Aiton) R. Br.),A shrub, belonging to the Apocynaceae family, although native to Asia, has adapted well to the Brazilian tropical environment.Has green fruits that turn yellow at the end of maturation, with numerous brown seeds, trapped by silky and long hairs, forming winged structures that allow their propagation through the air (Mariod et al., 2017).
The Silk Flower has several economical uses, such as forage production due to the there is no leaf fall even during the dry season of drought and crude protein content around 19.4% (Torres et al., 2010).An important characteristic of C. procera is its regrowth vigorous after cutting, giving this larger plant ease of handling and obtaining (Silva et al., 2017).It stands out as a raw material in the manufacture of fabrics, ornamentation, wood extraction for firewood and home made medicinal applications; its seeds are raw material for biodiesel production (Rangel & Nascimento, 2011, Oliveira-Bento et al., 2013).
Due to these characteristics, the study of the physiological quality of the seeds becomes important, since the seed is the basic input in the production, and vigorous plants originate from good quality seeds (Vechiat & Parisi, 2013).According to Henning (2005), the most efficient means of disseminating pathogens is by seed, which facilitates the introduction of diseases into new areas and reduces production due to seedling death.Thus, the use of alternative treatments appears as a preventive measure for problems related to the presence of pathogens in seeds, in addition to eliminating the fungal microflora, it is necessary that the treatment does not have negative effect on the physiological quality.
Alternative treatments have been gaining ground due to their efficiency in eliminating pathogens and reducing costs, in addition to the beneficial action to the environment, they do not leave residues, and avoid the resistance of microorganisms by the continuous use of chemical products (Santos et al., 2008, Lazarotto et al., 2009), and can replace fungicides, herbicides, insecticides and nematicides.
Among the alternative treatments, plant extracts and essential oils have effective fungal action; the results obtained are promising in the control of phytopathogens (Mondego et al., 2014).Santana (2015) working with Nim essential oils (Azadirachta indica A. Juss.);Thyme (Thymus vulgaris L.); Cinnamon (Cinnamomum zeylanicum J. Presl.);Camphor (Cinnamomum camphora L.) and Melalueca (Melalueca alternifolia).They observed a significant effect on both inhibition of mycelial growth (PIC) and Conidiapores.Boukaew et al. (2017) tested essential oils of Clove (Syzygium aromaticum (L.) Merr.& LM Perry) and Vatica (Vatica diospyroides) on the antifungal activity of Aspergillus flavus, and found that both contained Eugenou and Benzyl Acetate, antifungal compounds, in their compositions; the essential oil of V. diospyroides, showed 100% inhibition of A. flavus conidia, whereas S. aromaticum oil inhibited 84.7% of the conidia in Zea mays seeds.The use of copaíba essential oil considerably reduced the incidence of fungi associated with bean (Phaseolus lunatus) seeds without reducing the physiological quality of the seeds (Guedes et al., 2016).The antimicrobial activity of an essential oil is linked to its functional groups and their composition, such as alcohols, phenols, terpenes and ketones (Sartorelli et al., 2007).
Because of the importance of C. procera and action provided by the use of essential oils with antifungal activity in seed treatment, aimed to verify the effects of Copaíba oil (Copaifera langsdorffii) and Cravo (Syzygium aromaticum) on the health and physiological quality of (Calotropis procera) seeds.

Material and Methods
The work was developed in the Laboratories of Seed Pathology and Seed Analysis, Federal University of Paraíba (UFPB), Campus II Areia, PB.Seeds of C. procera were obtained from the municipality of Tacima, PB 6°29′8″ South 35°37′51″ West.The seeds were collected randomly, directly from 4 matrices and in open fruits, at an advanced stage of maturation, and were then packaged in paper bags and benefited in the Seed Analysis Laboratory.
The treatments were constituted by Copaíba (Copaifera langsdorffii) and Cravo (Caryophyllus aromaticus L.) essential oils at concentrations of 0.5; 1.0; 1.5; 2.0% and the fungicide Captan® (240 g, i.a. 100 kg -1 seed).The control 0 (zero) corresponds to the immersion of the seeds in distilled and sterilized water (ADE).The seeds were immersed in the treatments for a period of five minutes, after which the sanity and physiological quality of the seeds were analyzed.This time was based on pre-liminary tests.
The sanitary quality of the seeds was evaluated by the method of incubation on filter paper (Blotter test), using 200 seeds (twenty replicates of 10 seeds) for each treatment.The seeds were distributed in Petri dishes, containing two sheets of filter paper (80 g/m 2 ) previously sterilized and moistened with sterile distilled water (ADE), incubated at 20±2 °C with photoperiod of 12 hours.The quantitative and qualitative evaluations of the fungi associated to the seeds were carried out after seven days of incubation, and the seeds were examined individually under the stereoscopic microscope.
The seed quality was determined by germination test (MAPA, 2009), using 200 seeds (four replicates of 50 seeds) for each treatment, using as substrate germitest®-type paper moistened with distilled water in the amount equivalent to three times the weight of dry paper (MAPA, 2009).Later they were placed to germinate in a germination chamber with a constant temperature of 30 °C, with photoperiod of 8 h light and 16 h dark (Oliveira-Bento et al., 2013).The evaluations for the first and last germination counts were performed at 5 and 10 days, respectively, after sowing (Oliveira-Bento et al., 2013).The results were expressed as percentage of normal seedlings (MAPA, 2009).
As for the vigor tests, the first germination count (FGC) was performed, which corresponds to the number of normal seedlings computed on the 5th day after the test installation and the germination speed index (GSI), both performed simultaneously with the test of germination, with evaluation of the seedlings daily, at the same time, from the first day after sowing.The evaluations were carried out until the last count (tenth day), using the formula proposed by Maguire (1962).
To evaluate the dry mass of the seedlings, 20 seedlings of each treatment were randomly chosen.The seedlings were conditioned in paper bags and placed in an oven at 65 °C until reaching a constant mass (48 hours), being weighed in an analytical balance (0.001 g).The mean dry matter mass of the seedlings was obtained by the quotient b seedling -1 The exper concentrat obtained in variance an

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There was of the esse were signi  BRS Gurgueira and Marataoã, in both varieties no differences were observed when comparing the control in the treatment with Copaiba oil, with a slight increase of the dry mass in the concentration of 2% of the oil of Andiroba.However, Mondego et al. (2016) recorded higher mean MS using Copaifera langsdorffii essential oil in this way proving beneficial effects and viability in their use.