Heliconias are tropical ornamental plants grown at temperatures of 18 to 34 °C (Jerez, 2007). They are cultivated commercially for the production of cut flowers, potted plants and indoor landscapes (Ribeiro-de Castro et al., 2007; Santos, Lombera, & Benitez-Malvido, 2009). The main producers of heliconias for cut flowers are the United States, the Caribbean Islands and South American countries such as Colombia, Brazil, Ecuador, etc. Major markets are the United States, Canada and Europe (Criley, 1991). In Colombia, for example, the commercial value per floral stem is from $1.15 to $1.90 USD (Aranda, Bello, & Montoya, 2007). In Mexico they are cultivated mainly in south-southeast states like Chiapas and Veracruz, due to their climatic conditions (Hernández-Meneses, López-Peralta, & Estrada-Luna, 2013; Murguía-González, Lee-Espinosa, & Landero-Torres, 2007).
The exotic and economic importance of heliconias is affected by various social, economic, marketing and production factors. Heliconia production is adversely affected by inadequate fertilization and poor water supply (Andrezza-da Silva, Janie-Mendes, & Niraldo-José, 2011). Among the technological factors, chemical and organic fertilization is used in the production and nutrition of heliconias, since it is one of the most significant elements for ensuring inflorescence (Sushma, Reddy, Kulkarni, & Patil, 2012), in addition to quality and disease resistance (Cerqueira, Fadigas, Pereira, Gloaguen, & Costa, 2008; Ribeiro-de Castro et al., 2007). The proper fertilization dose helps to generate higher yield and performance in this species (Sushma et al., 2012).
Organic fertilizers help optimize crop growth and development (Albuquerque, Rocha, Costa, Farias, & Bastos, 2010; Koller, Koch, & Degen, 2014; Myint, Yamakawa, Kajihara, & Zenmyo, 2010), such as biol (fermented liquid fertilizer), which can be applied to the leaves or soil (Galindo, Jerónimo, Spaans, & Weil, 2007; Russoa, 2001; Ubalua, 2007).
Irrigation can be a limiting factor for the growth, production and quality of heliconias, affecting their useful life (Díaz, Mansito, Pérez-Díaz, Cid, & Socorro, 2008; Fischer & Beiner, 2005; Šarapatka, Rak, & Bubenikova, 2006). Considering the importance of water, superabsorbent polymers (SAPs) have been used to increase soil water retention and space out irrigation frequencies; they also help to absorb organic nutrients and minerals that increase the ecological use and efficiency of fertilizers (Qu, de Varennes, & Cunha-Queda, 2010; Ramos-González, Velázquez-Manzano, de la Rosa-Loera, Valdés-Flores, & Segura-Ceniceros, 2009; Šarapatka et al., 2006).
Based on the above, the twofold aim of this study was to: a) analyze the effect produced by foliar and soil fertilization with biol (fermented liquid fertilizer), soil chemical fertilization and application of superabsorbent polymers on the growth of heliconia (Heliconia psittacorum cv. Tropica) and b) generate information to help make efficient use of water and obtain nutrients with a beneficial economic and operational impact for heliconia producers.
Materials and methods
The research was carried out from February to August 2015 in a nursery located in Almagres, Sayula de Alemán municipality, Veracruz, Mexico (17° 80” NL, 94° 91” WL and at 40 masl). During crop development, the average temperature was 32 °C.
The soil collected for heliconia cultivation had the following characteristics: pH 6.47, 2.49 dS∙m-1 electrical conductivity, 30.93 % organic matter, 0.85 % total N, 17.2 mg∙kg-1 N-NH4, 8.7 mg∙kg-1 N-NO3, 59.69 mg∙kg-1 P, 1,430 mg∙kg-1 K, 59.9 cmol∙kg-1 cation exchange capacity, 0.78 t∙m-3 bulk density, 78.41 % field capacity and sandy-loam texture. The amount of substrate per pot, on average, was 2.472 kg.
Experimental design and treatments
A randomized complete block design with a slit-plot array (A x B x C) and four replicates was used. The factors were: A) soil fertilization, B) foliar fertilization and C) SAP presence. One rhizome per experimental unit was established, giving a total of 64.
The biol was prepared in a stationary-type artisanal biodigestor, according to the cattle manure, cane molasses and Mucuna sp. (58, 22, 5 and 15 %, respectively). In the bio for the soil, water, cattle manure, cane molasses and soybean paste (58, 22, 10 and 10 %, respectively) were used. The fermentation procedure lasted 60 days. Tables 1 and 2 show the characteristics of the two types of biol, obtained through laboratory analysis.
||OM (%)||Total N (mg∙L
For sowing, the rhizomes were harvested, a cut was made to the pseudostem to leave it 20 cm long and very long and dead roots were removed. Finally, the basal part of the rhizome (where the cut was made) was immersed in a captan solution (1 g∙L-1). In each 22 x 20 x 17 cm pot, a rhizome was placed in the center at 5 cm deep.
At the start of sowing, per pot, we applied: biol to the soil (20 mL∙plant-1), foliar biol (17 mL∙plant-1), superabsorbent polymers (2 g∙plant-1) and chemical fertilizer (5 g∙plant-1). The first was repeated at 30, 60, 90, 120 and 150 days after sowing (das) and the second at 60, 90, 120 and 150 das. For the application, a backpack pump was used without employing tackifier or surfactant. The superabsorbent polymers used were Silos de agua®, which were applied at 10 cm from the plant and buried at 10 cm. Of the chemical fertilizer (commercial formula 17-17-17 of N, P and K), two more applications were made at 60 and 120 das, based on the procedure proposed by Baltazar-Bernal, Zavala-Ruiz, and Hernández-Nataren (2011).
In order to induce flowering, three applications of biogib® (gibberellin) were made in all treatments every 15 days from the fifth month (150 das). Methomyl (90 %) was used for pest control. Irrigations were carried out every three days in all treatments until the crop adaptation period (first two months); afterwards, the irrigations were carried out at field capacity (70 %).
The evaluated variables were: plant height, health, vigor, color, number of leaves, leaf area and number of shoots. Plant height (cm) was measured from the base of the plant to the highest leaf. Health was determined with a qualitative scale ranging from 1 to 5, where 1 is 100 % or unhealthy plant and 5 is 0 % or healthy plant. Vigor was obtained with a qualitative scale ranging from 1 to 5, where 1 is weak plant and 5 is vigorous plant. Color was measured based on the Munsell Color Charts for Plant Tissues®, for which the scale was 1 for yellow, 2 green-yellow, 3 green and 4 very green, considering section 2.5 GY (green-yellow). All these variables were measured at 30, 90 and 180 das. Leaf area (cm2) was determined at 60, 120 and 180 das; for this, 0.74 multiplied by the length and width of the highest plant leaf (Farias, Albuquerque, Filho, & Reis, 2013). Finally, the number of shoots per plant was counted at 180 das.
For the analysis of variance, square root transformations were made to the original data of the variables number of leaves, vigor, color, number of shoots and health.
With the analysis of the seven variables in five samplings, the significance of the individual effects (soil fertilization, foliar fertilization and SAP application) and their interactions were determined (Table 3). For the analysis of variance, a randomized complete block design with a split-plot arrangement was used. Tukey’s range test (P ≤ 0.05) was performed using the Statistical Analysis System statistical package (SAS, 2014).
||FF||SF X FF||SAP||SF X SAP||FF X SAP||SF X FF X SAP|
|Height 30 das2||0.001*||0.267||0.063||0.519||0.225||0.253||0.726|
|Height 90 das||0.002*||0.539||0.297||0.729||0.003*||0.518||0.254|
|Height 180 das||0.000*||0.059||0.001*||0.325||0.617||0.061||0.001*|
|Leaf area 60 das||0.022*||0.122||0.040*||0.800||0.019*||1.000||0.309|
|Leaf area 120 das||0.000*||0.015*||0.141||0.241||0.169||0.125||0.504|
|Leaf area 180 das||0.003*||0.030*||0.007*||0.007*||0.000*||0.110||0.000*|
|Health 30 das||0.539||0.876||0.050*||0.617||0.105||0.186||0.932|
|Health 90 das||0.003*||0.938||0.014*||0.653||0.027*||0.810||0.056|
|Health 180 das||0.002*||0.757||0.004*||0.791||0.687||0.508||0.579|
|Vigor 30 das||0.013*||0.558||0.192||0.056||0.053||0.113||0.403|
|Vigor 90 das||0.000*||0.892||0.001*||0.893||0.003*||0.770||0.066|
|Vigor 180 das||0.002*||0.257||0.257||0.150||0.090||0.062||0.115|
|Color 30 das||0.000*||0.192||0.001*||0.619||0.042*||0.098||0.951|
|Color 90 das||0.000*||0.012*||0.002*||0.589||0.170||0.059||0.110|
|Color 180 das||0.000*||1.000||0.931||1.000||0.866||0.913||0.870|
|Number of leaves 30 das||0.220||0.548||0.012*||0.091||0.000*||0.613||0.353|
|Number of leaves 90 das||0.825||0.082||0.255||0.599||0.023||0.292||0.062|
|Number of leaves 180 das||0.719||0.588||0.127||0.647||0.364||0.122||0.248|
|Number of shoots 180 das||0.162||0.256||0.152||0.279||0.085||0.613||0.045*|
Results and discussion
This factor was statistically significant (P ≤ 0.05) for the variables plant height, health, color, vigor and leaf area (Table 3). According to Tukey’s range test (P ≤ 0.05), it was found that for plant height, color, vigor and health, the treatments with the best behavior were soil chemical fertilization and chemical fertilization + biol to the soil, with final heights of 176.3 and 194.29 cm, respectively (Table 4), while the number of leaves was highest at 180 das in the biol fertilization to the soil (2.22, Table 5). The health, color and vigor scales presented values of 4, which contrasted with the control treatments and with the application of biol only, since they had values of three (Table 6).
|Factors||Levels||Height (cm)||Leaf area (cm
|30 das*||90 das||180 das||60 das||120 das||180 das|
|Soil fertilization||Biol||31.2 az||83.1 b||164.9 b||230.2 ab||505.3 ab||834.0 ab|
|Chemical fertilizer||30.4 a||105.9 a||176.3 ab||293.4 a||666.6 a||764.3 b|
|Control||29.3 ab||85.7 b||162.9 b||197.1 b||415.6 b||745.5 b|
|Biol + chemical fertilizer||23.0 b||83.1 b||194.2 a||209.1 b||558.3 ab||924.7 a|
|Foliar fertilization||Foliar biol||29.2 a||90.9 a||172.3 a||247.93 a||562.8 a||903.0 a|
|Without foliar||27.7 a||89.6 a||176.3 a||217.0 a||510.2 b||808.3 b|
|SAP application||With SAP||29.1 a||91.4 a||172.9 a||230.4 a||518.5 a||909.1 a|
|Without SAP||27.9 a||89.1 a||176.3 a||234.5 a||554.5 a||802.1 b|
|Factors||Levels||Number of leaves||Number of shoots 180 das|
||90 das||180 das|
|Soil fertilization||Biol||1.87 az||2.15 a||2.22 a||1.87 a|
|Chemical fertilizer||1.91 a||2.13 a||2.21 a||1.91 a|
|Control||1.85 a||2.10 a||2.16 a||1.85 a|
|Biol + chemical fertilizer||1.70 a||2.16 a||2.19 a||1.70 a|
|Foliar fertilization||Foliar biol||1.85 a||2.19 a||2.18 a||1.85 a|
|Without foliar||1.82 a||2.08 a||2.20 a||1.77 a|
|SAP application||With SAP||1.77 a||2.15 a||2.18 a||1.84 a|
|Without SAP||1.89 a||2.12 a||2.21 a||1.78 a|
||90 das||180 das||30 das||90 das||180 das||30 das||90 das||180 das|
|Soil fertilization||Biol||1.75 az||1.78 b||1.94 ab||1.53 a||1.80 bc||1.84 a||1.27 b||1.65 b||1.67 b|
|Chemical fertilization||2.16 a||2.12 a||2.01 a||1.57 a||2.17 a||1.10 b||1.80 a||2.0 a||1.93 a|
|Control||1.68 a||1.79 b||1.81 b||1.45 b||1.73 c||1.81 a||1.19 b||1.62 b||1.47 b|
|Biol + chemical fertilization||2 a||2 ab||1.96 ab||1.28 b||2.06 ab||1.89 a||1.43 ab||1.91 a||1.93 a|
|Foliar fertilization||Biol foliar||1.25 a||1.93 a||1.93 a||1.48 a||1.95 a||1.93 a||1.46 a||1.81 a||1.75 a|
|Without foliar||1.26 a||1.92 a||1.93 a||1.44 a||1.94 a||1.89 a||1.38 a||1.57 b||1.75 a|
|SAP application||With SAP||1.22 a||1.90 a||1.94 a||1.51 a||1.95 a||1.93 a||1.44 a||1.78 a||1.75 a|
|Without SAP||1.30 a||1.95 a||1.93 a||1.48 a||1.94 a||1.89 a||1.41 a||1.80 a||1.75 a|
Sushma et al. (2012) report 156 cm in height in Heliconia psittacorum cv Golden Torch, values that differ from those found in this study. The greatest growth, due to the combination of chemical and organic fertilizers, is due to the improved absorption availability of the main nutrients (N, P, K, Ca, Mg, S and Zn). This, for the most part, is provided by the chemical fertilizer in Heliconia psittacorum cv. Tropica, in particular in cell elongation and multiplication (Bittencourt-Ferreira, & Oliveira, 2003; Clemens & Hugh-Morton, 1999; Matos-Viégas et al., 2014; Oliveira-Stringheta, Martínez-Prieto, Cardoso, & Alves-da Costa, 2003).
It is important to note that during the experiment 15 g∙plant-1 of chemical fertilizer were used, which was probably a low dose considering those applied by Matos-Viégas et al. (2014) and Albuquerque et al. (2010), who used 50 to 150 g∙plant-1 of the formula 15-15-15 of N, P, K. This could be the reason for the zero emission of inflorescences in this study. The best result of this combination is explained by the short-term effect of the chemical fertilizer and the medium-term complement of the organic fertilizer (biol). The latter is caused by the micronutrients (Fe, Cu, Zn, Mg and B) that they can provide, as they meet the needs of the plant, resulting in a better appearance in terms of color and health (Matos-Viégas et al., 2014).
In relation to leaf area, significant statistical differences (P ≤ 0.05, Table 3) were obtained. Table 4 shows that the soil chemical fertilization treatment excelled at 60 and 120 das (293.4 and 666.6 cm2, respectively), and at 180 das the combination of chemical fertilizer + biol to the soil (924 cm2) stood out.
Ribeiro-de Castro, Gomes-Willadino, Loges, Arruda-de Castro, and Souza-de Aragão (2015) reported 299 cm2 of leaf area by applying N, P, K, Ca, Mg and S in Heliconia psittacorum x Heliconia spathocircinata Golden Torch. These values were also lower and different from those found in this research. Farias et al. (2013) mention that an adequate balance of the nutrients N, P and K in chemical fertilization stimulates the plant canopy and leaf area, increasing the interception of solar radiation and photosynthesis, resulting in increased growth. Cerqueira et al. (2008) and Ribeiro-de Castro et al. (2007) indicate that this process can manifest itself in crop health and disease resistance.
The number of leaves obtained, on average, was five in all treatments up to 180 das (Table 5). Some authors such as Albuquerque et al. (2010) and Farias et al. (2013) mention that the issuance of the flower is from the fifth leaf, in the case of H. psittacorum Golden Torch. For her part, Sosa-Rodríguez (2013) states that the start of the flowering period depends on the species; the fastest ones, such as H. psittacorum, take six months from the time of planting to produce their first flowers.
In the present study the flowering process was not reflected at six months of growth, although gibberellin was used to induce it in a shorter time. This resulted in stem and leaf lengthening, as indicated by Treder, Matysiak, and Nowak (1999) in Cyclamen L. and Khan & Tewari (2003) in Dahlia y Tulipa L., as they observed an increase in height without the onset of inflorescences, after the application of gibberellins (gibberellic acid GA3).
The analysis of variance showed statistical significance (P ≤ 0.05) in leaf area at 120 and 180 das and in color at 90 das (Table 3). According to the means test (Tukey, P ≤ 0.05), the best treatment was biol fertilization in both variables (Tables 4 and 6, respectively).
Foliar biol application had a positive effect from 90 days (Table 4), which could be explained as a function of the leaf, since it is the most important plant organ by taking advantage of the nutrients applied by spraying (Tisdale, Nelson, & Beaton, 1985). In this case, the amount of nutrients present in the foliar biol caused an effect in the early growth stages, allowing the immediate incorporation of the essential elements into the metabolites that are generated in photosynthesis (Trinidad & Aguilar, 1999). This coincides with the findings reported by He, Pheng, and Chong (2000), who mention that increasing the leaf angle leads to an increase in photochemical efficiency.
The analysis of variance showed significant statistical differences (P ≤ 0.05) only in leaf area at 180 das in SAP treatments (Table 3). With SAP application, this variable reached 909.1 cm2 (Table 4).
By not finding important effects when using SAP, it is estimated that the requirements indicated by Díaz et to Prieto-Ruiz et al. (2004), in assessing the effect of water stress on the growth of P. engelmannii plants, growth rates were higher in the treatment without moisture restriction than in those plants subjected to stress. Also, Maldonado-Benitez, Aldrete, López-Upton, Vaquera-Huerta, and Cetina-Alcalá (2011) found that applications with SAP (2 and 4 g∙L-1), plus substrates that store a lot of moisture, had the best results.
Interactions between treatments
Soil fertilization with foliar application
In the interaction between soil and leaf fertilization, highly statistically significant differences (P ≤ 0.05) were found in plant height (180 das), leaf area (60 and 180 das), health (30, 90 and 180 das), color (30 and 90 das), vigor (90 das) and number of leaves at 30 das (Table 3). Likewise, leaf area and plant height presented their highest value at 180 das (924.7 cm2 and 194.2 cm, respectively) with the soil chemical fertilization plus biol treatment (Tables 4).
Acid pH solutions favor phosphorus absorption and this is greater with the ion Na+ and NH4+ (Reed & Tukey, 1987); in this case, foliar biol has a pH of 3.7. The concentrations of phosphorus and NH4+ obtained in foliar biol (Table 1) favored the color of the heliconia leaves. Thus, it is verified that the insufficiency of a nutrient, as was the case with the control (without application), can cause visible irregularities, such as nitrogen deficiency, which manifests as a yellow coloration on the leaves (Malavolta, Gomes, & Alcarde, 2002).
Foliar fertilization provides plants with microelements that are not present in the fertilizers that are applied in the soil, in this case biol + chemical fertilizer, which helps improve plant growth and development (Trinidad & Aguilar, 1999).
Soil fertilization with SAP application
Table 3 shows significant statistical differences (P ≤ 0.05) in the soil fertilization and SAP application interaction for the variables plant height (90 das), number of leaves (30 das), leaf area (60 and 180 das), vigor (90 das) and color (30 das).
It is important to note that during crop development the average temperature was 32 °C, which is considered high for heliconias according to Jerez (2007), Murguía-González et al. (2007) and Sosa- Rodríguez (2013), who indicate that the optimal temperature for its development is 28 °C, as they are able to tolerate between 25 and 32 °C. The observation shows that the high temperatures were associated with a higher moisture demand by the crop, since nine supplementary irrigations had to be applied with the rains recorded during the study. The above justifies the null effect of SAP application (Table 4), because in spite of having the same number of irrigations the plants did not present greater growth (29.1 cm at 30 das) than the control (29.3 cm at 30 das). However, Díaz et al. (2008) recommend from 2 to 5 L∙m-2∙day-1 of irrigation in heliconias, depending on the state of the crop and time of year.
Soil fertilization + foliar application + SAP application
Plant height and leaf area showed significant statistical differences (P ≤ 0.05) in this interaction at 180 das (Table 3). These results coincide with those of Albuquerque et al. (2010), who indicate that soil chemical and organic fertilization, together, lead to good results in crops, and its supplementation with foliar fertilization helps to correct microelement deficiencies (Kolota & Osinska, 2001).
Regarding the application or not of SAP, it is better to use substrates with high levels of organic matter or that retain moisture, which will result in a greater amount of stored water and reduced irrigation. This coincides with Santos, Timbó, Carvalho, and Morais (2006) and Albuquerque et al. (2010), who recommend in Heliconia bihai and Heliconia Golden torch substrates rich in organic matter.
In this interaction, the number of shoots presented significant statistical differences (P ≤ 0.05, Table 3). This result implies that the nutrients of the chemical and organic fertilizer, available in the substrate, facilitated the emission of shoots, and the application of the polymers can reduce irrigation frequencies (Abedi- Koupai, Saeid-Eslamian, & Asad-Kazemi, 2008). The latter leaves the nutrients available for when the plant needs them, since leaching or washing, caused by frequent irrigation, can cause N and P deficiencies that affect the number of shoots (Ribeiro-de Castro et al., 2015).
With soil fertilization, the plants of Heliconia psittacorum cv. Tropica significantly increase their height and leaf area, and their health, vigor and color are also improved, results influenced by the treatments of chemical fertilizer + biol to the soil and only chemical fertilizer to the soil.
With foliar biol applications, significant effects were shown at 120 and 180 das in leaf area, so this treatment can be a complement for soil fertilization in heliconia.
The use of SAPs did not show significant increases in the study variables. Even though SAPs store water, no effects were found on the growth of Heliconia psittacorum cv. Tropica. For this reason, the use of substrates with a high level of organic matter is suggested.