Use of trays in seedling production ​

The arugula (Eruca sativa) belongs to the Brassicaceae family, the same as cabbage, also called pinchão, it produces leaves that are very popular in salads. Its leaves are elongated and the blade is indented, with a dark green color and a spicy flavor (Filgueira, 2003). It is worth mentioning that its cultivation can be carried out through the production of seedlings, as well as direct sowing in beds. However, due to the small size of its seeds, the importance of working with the seedling production system stands out, as it offers greater ease of management in relation to the spacing between plants and between lines, in addition to controlling weeds, culminating in in more uniform plants (Pereira & Puiatti 2005). 

When considering the production of seedlings, the use of trays is a technique that brings many advantages to the producer, increasing productivity and product quality, in addition to reducing the amount of seeds used (Filgueira, 2003).

The trays can be made of Styrofoam or plastic, with different sizes. However, the vast majority have dimensions of 68cm x 34cm and the number of cells (128, 242, 284, 288, etc.) is defined according to the type of seedling to be formed. The cells can have a pyramid or inverted cone shape with the aim of guiding the roots to the bottom, where they are perforated, providing natural pruning of the roots (Wendling & Gatto 2001).

There are several options for sizes and types of trays to be used in the production of vegetable seedlings. However, there is a certain preference for using trays with smaller cells, as the smaller the cell volume, the greater the number of seedlings and the lower the need for substrate, with a consequent lower production cost (Godoy & Cardoso, 2005).

Regarding the substrates used in the trays, the material must be free of pathogens and weed seeds, with good physical quality and a source of nutrients. The use of substrate helps with transplanting with the formation of clods. It can be composed of expanded vermiculite, organic materials, fertilizers and additives (Filgueira, 2008).

According to Filgueira (2008), the right age for transplanting seedlings varies, depending on agroecological conditions and the species. The depth depends on the species. In the case of seedlings with a barely visible stem, planting at the height of the root ball is recommended. Care must be taken to help the resumption of development after the stress caused by the transplant.

Experiment

With the aim of evaluating the influence of trays with different cell sizes on arugula production (Eruca sativa Miller) and in the development of plants in the bed, an experiment was conducted, during the months of September and October 2017, in the greenhouse and in the experimental field of Univag – Centro Universitário de Várzea Grande - MT. Broadleaf arugula cultivar (Eruca sativa).

The experimental design was completely randomized (DIC) with three treatments, represented by trays of 128, 200 and 288 cells, each treatment with seven replications, totaling 21 plots.

 The trays with 128, 200, 288 cells were filled with the commercial substrate, whose components were biostabilized pine bark, vermiculite, charcoal mill, phenolic foam water. Subsequently, the trays were wet to better adhere the substrate and remain in the cells. Then, sowing was carried out, with five seeds per cell.

The trays were kept in a protected greenhouse covered with transparent plastic canvas, positioned on wooden stands one meter away from the ground. The seedlings were irrigated twice a day using a ten-liter watering can. Thinning was carried out seven days after emergence (DAE) of the seedlings, leaving one arugula seedling per cell.

The beds were prepared and raised manually with a hoe, preparing two beds measuring 15cm high from the ground, 19m long and 1,20m wide. 50% shade cloth was used as cover for the beds, where samples were collected for soil analysis (Table 1).

Following the recommendations of Filgueira (2000) for arugula cultivation, broadcast fertilization was carried out with 110,41g of urea, 30 days before transplanting the arugula seedlings.

The seedlings were transplanted to the beds at 22 DAE, when they reached three to four leaves, the trays of which were irrigated beforehand to facilitate handling without damaging and stressing the seedlings. After transplanting, rice husks were thrown onto the beds with the aim of improving the biological conditions of the soil, such as controlling humidity. The beds were irrigated using a ten-liter watering can, irrigated once a day.   

The evaluations were carried out in two moments, one during the transplantation of the seedlings, on September 23, 2017, and another after the final development of the plants in the bed, on October 27, 2017, where five plants were evaluated per repetition. at each stage of the assessment. The variables evaluated were number of leaves, length of the largest leaf (cm), total length (cm), green mass (g) and dry mass (g).

With the aid of a 30cm ruler, the variables of length of the largest leaf (cm) and total length of the plant (cm) were evaluated for both stages of the evaluation. The length of the largest leaf was measured from the leaf petiole to the end of the central vein. The total length of the plant was considered to be the vertical distance between the neck of the plant and the end of the last developed leaf.

Subsequently, the samples collected in the field were washed in running water to remove impurities and taken to the laboratory to determine leaf green mass and leaf dry mass.

To determine green mass in the first evaluation, the seedlings were weighed on a precision scale. However, in the second evaluation, due to the size of the arugula plants, weighing to determine the green mass was carried out on a conventional scale. After determining the green mass, in both evaluations, the plants were placed in identified paper bags, taken to a forced air circulation oven (65°C) for 72 hours to determine the dry mass and were subsequently weighed. on a precision balance.

 To evaluate the data, analysis of variance was performed, and the means were compared to the Tukey test at 5% probability.

Results

The averages observed for number of leaves (NF), length of the largest leaf (CMF), total length (CT), green mass (MV) and dry mass (MS), at 21 days after sowing, it was verified that the treatment with the tray of 128 cells provided a greater number of leaves, length of the largest leaf, total length and green mass when compared to the other treatments. However, a higher dry mass was found when using the 288-cell tray. There was no statistical difference between the use of the 200 and 288 cell trays for the variables studied, except for dry mass (Table 2).

The results observed in the first stage of the experiment are in line with those found by Crippa (2015) who, when evaluating the development of cabbage in different types of tray and substrate, found that the tray with 128 cells stood out when compared to those with 200 cells and 288 cells. This is probably due to the greater volume of substrate that surrounds the plant in the 128-cell trays, due to the greater space and volume of substrate around the seedling, and consequently more nutrients and water available, which provides more favorable conditions for its development. (Oliveira et al. 1993).

Salvador et al. (2001) noted in their studies that trays with smaller cells, due to the higher concentration of roots, require more oxygen and CO2 removal, thus becoming vulnerable to water stress, due to the amount of substrate, which is not always sufficient to retain moisture. -water supply to maintain turgidity.

On the other hand, seedlings produced in larger cells promote earlier cultivation of the crop and consequently a faster harvest compared to seedlings produced in trays of smaller cells. Therefore, the use of trays with larger cells is a favorable alternative for the farmer, as larger and heavier vegetables are an important characteristic for later commercialization (Reghin & Otto, 2003).

At 25 days after transplantation, it was found that trays with 128 and 200 cells provided higher averages observed for all variables analyzed in the study, when compared to treatment 3 with the use of 288 cells (Table 3).

Although the 128-cell tray, in the 1st evaluation, presented the best result statically, in the 2nd evaluation, the plants produced in the 200-cell tray were statistically equal, therefore, a recovery of the arugula plants was noted, when they were placed in a place where they found more favorable conditions for their development.

Similar results were reported by Marques et al (2003) who found that the best lettuce seedlings were produced in the 128-cell tray. However, the seedlings produced in the 200-cell trays showed better recovery in the field in the variables number of leaves, green mass and dry mass, statistically equaling the seedlings from the 128-cell trays. In relation to the seedlings produced in the 288-cell tray, they obtained the worst results statically in all variables evaluated and in both evaluations, thus agreeing with the present experiment. 

In studies carried out by Echer et al (2000) a difference was noted in the quality of the seedlings, even 55 days after transplanting. However, over time the differences decrease and may even disappear as the crop cycle lengthens. It is also observed that if the cycle is prolonged until the plants reach the harvesting point, there is a gain in production due to the compensatory delay in harvesting.

Despite observing that trays with 128 and 200 cells presented plants with greater development, Farinacio (2011) noted that nurserymen and seedling traders have a greater preference for using trays with 288 cells, as they consider them more advantageous due to the greater concentration of seedlings in a reduced space, smaller substrate volume and easier transportation compared to trays with 128 and 200 cells.   

CONCLUSION

For the production of arugula seedlings, it is recommended to use Styrofoam trays with 200 cells, as they make it possible to obtain better adult plants as well as the seedlings produced in trays with 128 cells, combining the advantage of financial savings, substrate and physical space, when compared to other trays. With a 25kg bag of commercial substrate, which costs an average of R$41,50, approximately 31 trays with 200 cells can be filled, while the same amount of substrate fills approximately 20 trays with 128 cells. 

Magda Liz Tavares Velasquez, Univag - University Center of Várzea Grande

Growing Vegetables and Fruits November 2019

With each new edition, Cultivar Hortaliças e Frutas publishes a series of technical content produced by renowned researchers from all over Brazil, which address the main difficulties and challenges encountered in the field by rural producers. Through research focused on controlling the main pests and diseases in vegetable and fruit cultivation, the Magazine helps farmers in the search for management solutions that increase their profitability. In the November 2019 edition you can also see: 

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