Development of Datura metel in different pot sizes

Datura metel L. belongs to Solanaceae family and presents medicinal and ornamental potential. The use of D. metel as an ornamental plant is still unexplored, however there is a need to gather more information about this species planting, especially for pot cultivation. This study aimed to verify the effects of different pot sizes in the development of D. metel, in order to enable the use of this species in the potted flower market. The work was conducted in a greenhouse at the Biotechnology Department located at Center of Agricultural Sciences of the Federal University of Paraíba (CCA-UFPB), Areia, PB, Brazil. The experimental design used was completely randomized with 3 treatments (pot sizes: T1 = 0.82 dm, T2 = 1.55 dm e T3 = 3.68 dm) and 10 replications. The variables analyzed were: plant height, stem diameter, canopy diameter, number of ramifications, leaf length, leaf width, leaf number, flower number, flower length, flower diameter, chrolophyll a e chrolophyll b. The data obtained was submited to analysis of variance and later on clustered based Tukey’s test (5%). All the analyses were made on GENES software. There is variation between treatments for characteristics evaluated. Treatments 2 (1.55dm) and 3 (3.68dm) had similar values and the highest mean values for the characteristics of plant height, number of leaves and chlorophyll b. The size of the vase influences the development of the Angel’s trumpet (D. metel). Pot size influences D. metel development. The medium size recipient (1.55 dm) is recommended for cultivation of D. metel because it presents ideal plant development, such as plant height and number of leaves, for use with ornamental species pots.


Introduction
Datura metel L. is a species from the Solanaceae family used in medicine as it presents substances with great anesthetic potential (Liu et al, 2020) and promising in the psoriasis treatment (Yan et al., 2019). Commonly known 'Devil's Trumpet' or 'Angel's Trumpet', (Tohmé, 2014), it is a bush naturalized in Brazil with distribution in the Northeast among states of Alagoas, Bahia, Ceará, Maranhão, Pernambuco e Piauí (Stehmann et al., 2015).
This species produces chemical compounds to defend itself from predators and pathogens and due to that may also be toxic and irritable for other organisms, including human beings (Trancrã et al., 2017). This species may also be used as an ornamental plant like Datura suaveolens Humb. & Bonpl. ex Willd. (Solanaceae), popularly known as trombeta, trombeta-deanjo ('Angel's Trumpet'), trombeteira, cartucheira, zabumba and saia-branca . Despite the toxicity, many are cultivated as ornamental plants due to their beauty and differ from other plants for its flower colors, shapes and overall aspects (Teixeira, 2020).
Currently, drastic changes occurred in population habits due to social isolation needed to prevent COVID-19. Practices such as flower contemplation stand out and are seen as self-care, called hortitherapy (Reis et al., 2020). Hortitherapy is a form of connection with nature, especially in times of social distancing in internal spaces. Besides the dependency between humans and plants when it comes to nutrition, oxygen supply, fuel and also medicine (Odeh e Guy, 2017), this relationship may go far beyond. Plants can be cultivated for its aesthetical characteristics. Ornamenting internal spaces has stand out even more in the last few years and it is not considered unnecessary because activities like gardening can be occupational therapy (Reis et al., 2020).
Floriculture market in Brazil has increased 10% in 2020, mainly in green plants and potted plants (IBRAFLOR, 2020). However, more information is essential about species planting in different size recipients, with the possibility to enhance this sector. Recipient dimensions influences in quality and production costs as well as in water and nutrients availability, architecture of root system, transportation and distribution . Barroso et al. (2012) highlighted a plant height/pot height ratio may vary from 1.5 to 2.0 in ornamental pepper and that ratio must to be considered since the plant architecture and pot size is an important element in determining quality of an ornamental species and it interfere in consumer preference.
An ornamental plant can have its growth harmonized through several factors, including the size of containers. Different genotypes, even those with more expressive growth, can be grown in pots, with their size monitored, in order to obtain a harmony of the plant, and even a better efficiency in the production of the aerial part (Pinto et al., 2010). Pirola et al. (2015) reported that countless materials can be used as a container in the development of chrysanthemum and pansy, ornamental species of great importance in the market, demonstrating that each container has a different influence on the root development of plants, consequently providing the largest total length of the plants. plants Concerning these characteristics, the development of scientific work related to pot adaptation, more efficient cultivation techniques that can guarantee lower production costs, becomes important. This study aimed to verify the effects of different pot sizes in the development of D. metel, in order to enable the use of this species in the potted flower market.

Material and Methods
Seeds of Datura metel were collected in a yard, from fruits of a single plant in the Bonfim settlement, municipality of Alagoinha (06º 57 '00" S, 35º 32' 42" W and altitude of 133 m), Paraíba, Brazil. This research was conducted in a greenhouse at the Biotechnology Department located at Center of Agricultural Sciences of the Federal University of Paraíba (CCA-UFPB), Areia, PB, Brazil.
Seeds were sown in styrofoam (polysterene) plates, containing 128 cells filled with commercial substrate Plantmax ® . When the plants had six permanent leaves they were transplanted to different plastic pots containing the same substrate.
The experimental design used was completely randomized with three pots sizes (treatments) T1 = 0.82 dm 3 , T2 = 1.55 dm 3 e T3 = 3.68 dm 3 and 10 replications, one plant per pot. The plants were irrigated manually and daily, based on field capacity, to maintain adequate humidity until full bloom.
Evaluations Measurements were made using a digital pachymeter (Digital Pachymeter Leetools ® ) and a graduated ruler. Values referring to quantity were taken by counting. Chlorophyll content were measured with a digital chlorophyll meter (ClorofiLOG -FALKER ® ).
The data was submitted to analysis of variance and later on Tukey's test (5%). All analyses were made on GENES software (Cruz, 2016).

Results and Discussion
The PH, SD, CD, NOR, LL, LW, LN, FN, and CLb presented significant differences (p≤0.01) among treatments (Table 1), showing that pot volume influenced on D. metel development.
The variables FN, FL and CLa were not significant, ( Table 1) which means that plant presented similar behaviors regardless of the applied treatment.
Even though plants presented a reduced size, due to pot diameter, flowers remained big which was disproportional to the pot and plant sizes (Figure 1), decreasing its aesthetical value and making them undesirable for commercialization as ornamental plants in small pots (0.82 dm 3 ). Even though plants presented a reduced size, due to pot diameter, flowers remained which was disproportional to the pot and plant sizes (Figure 1), decreasing its aesthetical value and making them undesirable for commercialization as ornamental plants in small pots (0.82 dm3). The treatment 1 (pot of 9,1 cm height) the plants had a height of 32.45 cm and flowers of 18.21 cm, while in treatments 2 (pot of 10,5 cm height) and 3 (15 cm height), they had plants with 47.52 cm and 52, 86 cm and flowers with 18.24 cm and 17.90 cm, respectively.  The coefficient of variation varied from 5.79% to 45.1%, for the characteristics: chlorophyll a and number of ramifications, respectively (Table 1). Some authors report that CV values vary according to the species and variable studied (Silva et al., 2011;Werner et al., 2012;Almeida et al., 2014), like observed in this paper. In this case the traits with higher CV values were number of ramification and flower length despite this the differences among treatments were highly significant showing that the variation among treatments were higher than the environment variation (Table 1).  Table 2).
The height of the plants decreased around 20 cm when compared to published works, e.g., Datura fastuosa height varies from 0.50 to 1.5 m (Al-Snafi, 2017). This fact makes pot size an alternative for reducing plant size, as a small pot may limit plant development by the volume of substrate used (Almeida et al., 2014). Pot size determines plant growth, altering the relationship intake/consumption (Campos e Ronchi, 2015). A small recipient implicates in a small amount of substrate and therefore, a decrease in water and nutrients availability for the plant. By reducing resources availability these pots generally prevent root growth and reduces photosynthesis probably for the total nutrient availability (Poorter et al., 2012).
Treatments 2 (1.55dm 3 ) and 3 (3.68dm 3 ) presented similar values and the greatest mean values for the characteristics: plant height (47.51 and 52.86), leaf number (2.80 and 2.40) and chlorophyll b (18.55 and 19.93) ( Table 2). Therefore, D. metel production is recommended in the 1.55 dm 3 pot as it presented the same performance as treatment 3 for those characteristics and needs a smaller volume of substrate. Determination of pot volume is important for each plant species because it affects plant growth, especially in protected environment (Guerra et al., 2020), however, pot size has had few reports in scientific literature and usually is not mentioned in papers (Poorter et al., 2012).
In potted plants it is important to have small sized and compact plants with good ramification, characteristics that vary according to several factors like cultivar and pot size (Pinto et al., 2003). Therefore, the correct pot choice is decisive to recommending an ornamental plant for cultivation in vases.
The choice of pot size for plant production is important because it influences several aspects and may impact the percentage of survival in the field and crop yielding, also influencing in root and aerial part growth (Lima et al., 2006), like observed in this work.
The medium size recipient (1.55 dm 3 ) is recommended for cultivation of D. metel because it presents ideal plant development, such as plant height and number of leaves, for use with ornamental species pots.