Production and Quality of Okra Fruits Submitted to Doses and Types of Biofertilizers

This study aimed to evaluate the yield and the quality of the fruits of two okra cultivars (Abelmoschus esculentus), due to the varying doses and types of biofertilizers. The experiment was conducted the period September to December of 2017, at the experimental Piroás Farm, in the city of Redenção-CE, Brazil. The experimental design used was entirely randomized, in factorial design 5 × 2 × 2, referring to the five doses of the biofertilizer (0, 0.5, 1, 1.5 and 2.0 L plant week), versus two types of liquid biofertilizers (bovine and caprine under aerobic fermentation) and two okra cultivars: Santa Cruz 47 and Clemson Spineless. The number of the fruits per plant, the average mass of the fruits, yield, the length and diameter of the fruit and peel thickness of the okra fruit, were increased according to the increase on the biofertilizers doses. The cultivar “Santa Cruz 47” presented higher values in the length of the fruit, whereas the cultivar “Clemson Americano 80” was superior in the variables “average fruit mass” and “diameter of the fruits”.


Introduction
The okra (Abelmoschus esculentus), belonging to the family Malvaceae, is an annual shrub-bearing plant, native to the African continent, whose fruits are rich in carbohydrates, proteins, vitamins, minerals and unsaturated fats (Filgueira, 2012).It is especially cultivated by family farmers, since it presents a fast vegetative cycle, resistance to pests and diseases, and low productivity cost, being widely planted in Brazil.According to data from the Agricultural Census, Brazil produced, in 2017, about 128,460 tonnes of okra, the Northeast being the second largest producer with 32,337 tonnes, corresponding to 25.1% of the national production (IBGE, 2018).
It should be emphasized that the cultivation management used by the farmers for this culture, employ low levels of technology, which limits the productivity potential of this culture, being necessary to adopt practices that promote gains in yield (Oliveira et al., 2013).An accessible alternative for the producers that has been quiet studied is the organic fertilization through biofertilizers.
The biofertilizers are liquid components, originated from the fermentation of organic compounds and water, under aerobic and anaerobic conditions, (Penteado, 2007) and because they have essential elements to the culture (Viana et al., 2013).According to Filgueira (2012), vegetables respond well to this type of fertilization, both in productivity and quality of the products obtained, with cattle manure being the organic source most used by the vegetable farmers.This organic fertilizer is of low cost and has been presenting satisfactory results, various studies confirm that the use of these inputs promote an increase in the vegetables yield.Oliveira et al. (2013), researching the okra yield fertilized with manure and bovine biofertilizer, it was found an increase in yield, when compared to the control treatment.Oliveira et al. (2014), a research on the yield of maxixe due to the doses of manure and bovine biofertilizer, verified that the yield of this culture has significantly responded to the use of bovine manure, associated with bovine biofertilizer, coming to a total yield of 13.8 t ha -1 on the 31.0t ha -1 dose of bovine manure.Santos et al. (2014a), investigating the quality of the melon plant fruits in the doses of biofertilizers, it was found that the transverse diameter of the fruits and the thickness of the pulp raised with the use of bovine biofertilizer.This form of fertilization contributes in a decisive way to the improvement of soil characteristics, enabling to reduce the cost of crop production, since the input that more drives up the cost of production of okra is mineral fertilizer used in planting and cover (Oliveira et al., 2014).
Based on the above, the main aim for the study was to evaluate the yield and the quality of the fruits of two okra cultivars due to the different doses and types of liquid biofertilizers.

Characteristics of the Experimental Area
The experiment was carried out from September to December 2017, the study was conducted at Piroás Farm experimental area in the University of International Integration of Afro-Brazilian Lusophony, located in Redenção-CE, Brazil under geographical coordinates: 04°14′53″ S, 38°45′10″ W and average altitude of 340 m.According to the Köppen-Geiger Climate Classification (Köppen, 1918), the region climate is classified as Aw', in other words, rainy tropical, very warm, with predominance of rain during the summer and fall seasons.

Management of the Soil and Plant on the Experiment
The material used as substrate came from the Argissolo Vermelho Amarelo EMBRAPA (2018).For evaluation of the soil conditions, a sample was collected before the treatment started and it was sent to the Soil and Water Lab of the Departamento de Ciências do Solo/UFC, whose results of chemical analysis can be visualized on Table 1.The okra seeds were seeded in sowings and 15 days after the establishment of seedlings were transplanted to plastic pots with 25 liter substrate capacity, in Full Sun conditions.It was installed a drip watering system, and the watering was done in daily frequency, according to the needs of each plant.

Experimental Delineation and Treatments Used
The experimental delineation was randomized, in factorial design 5 × 2 × 2, with five repetitions, coming to one hundred experimental units.The treatments were according to five doses of biofertilizers (0, 0.5, 1, 1.5 and 2.0 L plant -1 week -1 two types of liquid biofertilizers (bovine and caprine) and two okra cultivars (Santa Cruz 47 and Clemson Spineless 80).
The biofertilizers, using fresh manure of bovine and caprine origin, were prepared separately through aerobic fermentation with addition of water in proportion of 50% (volume of fresh manure/volume of water), for 30 days, in 200 liters recipients (Sousa et al., 2013).Following that, a mixture of the ingredients took place, using adapted aerator.
The level of mineral elements (Table 2), in the chemical composition of the liquid biofertilizers dry matter, were analyzed according to methodology suggested by Malavolta et al. (1997).
Table 2. Composition of macro and micronutrients essentials in the dry matter of biofertilizers (BIO) bovine (B1) and caprine (B2)

Produc
The harve packed in were perfo (MMF), ob with the re fruit diam expressed and produc expressed

Statisti
The observ referring to 1% and 5% analysis se adjusts to of probabi

Results
The

Discuss
The increa Spineless adequate q the organic P, K and N The result number of Similarly, there was a The manu and contrib of the cul 2013).The increase of the okra fruits diameter from increasing biofertilizer doses may be related to the availability of essential nutrients to the plants, which are provided by the biofertilizers (Viana et al., 2013), promoting greater growth of the fruit.Lima et al. (2018) found that the increase on the doses of bovine biofertilizer advanced the increase on the strawberry fruit diameter, in the dose of 500 mL per week -1 plant -1 , was responsible for the maximum diameter of 21.41 mm.Opposite results were found by Silva et al. (2016), where it was not found significant effect of the use of biofertilizer on the fig fruit diameter.

The differ characteris
Therefore, it can be verified that there are differences between the cultivars (Image 5B, that possibly is related to the genetic improvement, existing distinct morphological characteristics in the cultivars, consequently affecting the fruits attributes).
The increase in the thickness of the bark due to the increase of the doses of bovine and goat biofertilizer for the cultivars "Santa Cruz 47" and "Clemson Americano 80" can be justified by the fact that the potassium present in the biofertilizer increases the CO 2 fixation and promotes the transport of photoassimilates for the fruits, justifying the improvement in fruit quality (Meurer et al., 2018).
The superiority of the Clemson Spineless 80 cultivar compared to the the Santa Cruz 47 cultivar, can also be related to the physiological capacity of the culture in transport the nutrients in higher quantity to the phytomass.
Similar tendency was found by Santos et al. (2014), confirmed that the raise on the doses of biofertilizer, there was an increase on thickness of the mesocarp of the melon fruit.Rocha et al. (2013), testing the bovine biofertilizer (pure and enriched), also shows an increase on the peel thickness of the yellow passion fruit.

Conclusions
The raise on the doses of bovine and caprine biofertilizers favor the yield of fruits per okra plant and the fruit peel thickness, on the Santa Cruz 47 and Clemson Spineless 80 cultivar.
The bovine biofertilizer was more efficient to the raise on the average okra fruits mass.The increase on the doses contributed to higher fruit lengths.
The Santa Cruz 47 cultivar has superior value in fruit length, however the Clemson Spineless 80 cultivar, has higher levels in the variables: average mass and fruit diameter.

Figure
Figure 2. A