Bulb cutting methods to propagate Hippeastrum hybridum Hort.

 

Forma de corte del bulbo para la propagación de mancuernilla (Hippeastrum hybridum Hort.)

 

María Andrade-Rodríguez¹*; Dagoberto Guillén-Sánchez¹; Oscar Gabriel Villegas-Torres¹; J. Jorge Ayala-Hernández²; Víctor López-Martínez¹; Jesús Vargas-Araujo¹

 

¹ Posgrado en Ciencias Agropecuarias y Desarrollo Rural, Facultad de Ciencias Agropecuarias, Universidad Autónoma del Estado de Morelos. Av. Universidad, núm. 1001. Col. Chamilpa, Cuernavaca, Morelos. C.P. 62209, MÉXICO. Correo-e: mariamaria.andrade65@gmail.com, tel.: 5538447031 (*Autor para correspondencia).

² Departamento de Fitotecnia, Universidad Autónoma Chapingo. Carretera México-Texcoco km. 38.5. Texcoco, Estado de México, C.P. 56230, MÉXICO.

 

Received: May 18, 2014.
Accepted: April 6, 2015.

 

Abstract

Hippeastrum, commonly known in Mexico as Mancuernilla, is important in floriculture because of its beautiful flowers; it can be propagated by seeds, bulb separation and twin cataphylls. In Mexico, bulbs are imported from the United States and the Netherlands, meaning high investment costs for nursery growers; therefore, propagation methods are needed to provide inexpensive vegetative material for the commercial production of this ornamental. The objective of this study was to evaluate different bulb cutting methods for the propagation of Hippeastrum. Bulbs (8 cm) were used and nine cutting methods were studied: 1) the whole bulb, 2) basal section, 3) Λ cut in basal section, 4) basal section without central bud, 5) cutting basal section in half, 6) basal section into quarters, 7) longitudinal cut into quarters, 8) longitudinal cut into eighths and 9) basal section into quarters, separating each quarter into five groups of twin cataphylls. When the main bud was preserved, no bulbils were formed; when using the basal section: eliminating the central bud, cutting in half, and cutting into quarters, 5-6 bulbils were obtained; when the entire bulb was used and it was cut longitudinally into four and eight sections, 10 and 13 bulbils were obtained respectively. In contrast, when the basal section was cut into four parts, separating each quarter into five twin-cataphyll groups, 25 bulbils were obtained. It was concluded that Hippeastrum propagation was greater when the basal section of the mother bulb was cut into quarters and each quarter was separated into 5 twin-cataphyll groups.

Keywords: Bulbils vegetative propagation, twin cataphylls.

 

Resumen

Las mancuernillas son importantes en la floricultura por sus hermosas flores; se pueden propagar por semilla, separación de bulbos y por catafilos gemelos. En México los bulbos son importados de Estados Unidos y Holanda, lo que implica gran inversión para los viveristas; por tal motivo, es necesario tener métodos de propagación que permitan disponer de material vegetativo barato para la producción comercial de dicha ornamental. El objetivo de la presente investigación fue evaluar formas de corte del bulbo para la multiplicación de mancuernilla. Se usaron bulbos de 8 cm de diámetro y se estudiaron nueve formas de corte: 1) bulbo completo, 2) sección basal, 3) corte en Λ de sección basal, 4) sección basal sin yema central, 5) corte por mitad de sección basal, 6) sección basal en cuartos, 7) corte longitudinal en cuartos, 8) corte longitudinal en octavos y 9) sección basal en cuartos, separando cada cuarto en cinco grupos de catafilos gemelos. Cuando se conservó la yema principal no hubo formación de bulbillos; al usar la sección basal: eliminando la yema central, cortando por mitad, y cortando en cuartos se obtuvieron cinco a seis bulbillos; cuando se usó todo el bulbo y se cortó longitudinalmente en cuatro y ocho secciones se obtuvieron 10 y 13 bulbillos respectivamente; en cambio, cuando se usó la sección basal en cuatro partes, separando cada cuarto en cinco grupos de escamas se obtuvieron 25 bulbillos. Se concluyó que la multiplicación de mancuernilla fue mayor cuando la sección basal del bulbo madre se cortó en cuartos y cada cuarto se separó en cinco grupos de catafilos gemelos.

Palabras clave: Bulbillos, propagación vegetativa, catafilos gemelos.

 

Introduction

The native monocotyledons of Mexico most used for decorative purposes are: Agavaceae, Amaryllidaceae, Araceae, Arecaceae, Cannaceae, Nolinaceae and Orchidadeae, among others. Hippeastrum hybridum known in Mexico as Mancuernilla belongs to the Amaryllidaceae family, is a plant with beautiful flowers of different colors, suitable for cultivation in garden, potted or cut flowers; so this plant has a very important place in floriculture for sale (Leszczyñska-Borys & Borys, 2001; Vargas, Oropeza, & de García, 2006).

Bulbous plants propagate by themselves or can be divided manually; Hartmann, Kester, Davies, and Geneve (1990), without indicating the species they refer to, describe the methods of bulb propagation by bulbils and cuttings bulb; they mention that propagation using bulbils is a slow method, since the process from the start of the formation of the bulbil to flowering requires approximately four to five years. The bulbils can be harvested and planted on beds or rows, in nursery to grow to be large enough to flower. When multiplying naturally is not enough we can use induction to generate new bulbils, sometimes using an artificial stimulus like making some incision in the bulb in different ways: basal cutting, removing a portion of the bulb, dividing in half, among others. Bulb wounds stimulate the reaction of bulb scales through a hormonal mechanism and form more or less bulbils, which are strengthened during the rest period of the mother bulb (Sganzerla, 1973).

Hippeastrum is propagated by four methods: the first method is using seeds (Leszczyñska-Borys & Borys, 2000), the most efficient propagation method of bulbous plants whose vegetative propagation is slow (Schiappacasse, Peñailillo, & Yánez, 2002), is usually used to develop new varieties due to the large variation in the characteristics of flowers, plant form and flowering time; the second method is dividing bulbils and this method is used for cultivars that produce at least three bulbils; the third method is twin cataphylls used in most propagation cases (Vijverberg, 1981); propagation in vitro is the fourth method that has been used successfully for bulbous and in particular for Hippeastrum (Sultana et al, 2010;. Vargas et al., 2006; Zayed, El-Shamy, Berkov, Bastida, & Codina, 2011), however, to use this method fancy facilities and equipment are required.

Ephrath et al. (2001) report that less Hippeastrum bulbils were obtained when the mother bulb was divided into sections without separating the parts (a bulb per section). When having 32 scale groups, 27 bulbils were obtained; on the other hand, when having 48 groups 33 bulbils were obtained; this indicates that to increase the number of sections per bulb generates more bulbils. Zhu, Liu, and Yiu (2005) studied propagation, growth of bulbils, number of leaves in Hippeastrum and found that there was effect of various cutting methods. A total of 13.3 bulbils were obtained when longitudinal cut was made without separating the parts, 19.1 bulbils were obtained when 12 longitudinal cuts were made and 38.4 bulbils by cutting twin cataphylls; reporting that when the number of bulbils was greater bulbils had smaller diameter.

Yanagawa (2005) studied the propagation of ornamental bulbous and noted that 1.3 to 2.5 bulbs per segment of twin cataphylls were formed; indicating that there may be one or more buds per scale so when using the method of twin cataphylls we obtained 35.6 buds per bulb.

In Mexico there are no companies producing bulbs, so the propagation material is generally imported from the United States, the Netherlands and Germany. The companies importing bulbs are: Grupo Nedermex, Akico, Stigma Internacional, Viveros Atlixco and Bulbos de Holanda. The main states producing Hippeastrum are Morelos, Puebla and State of Mexico (7,800, 6,500 and 1,000 plants per cycle respectively). In 2013 the cost of the bulbs was: bulbs of flower with single corolla $45 MXN and $67 MXN, for small bulbs and large bulbs respectively; bulbs with double corolla $70 MXN small bulbs and $88 MXN for large bulbs. This shows the great investment for nursery growers of Hippeastrum. The wholesale selling price was $150 MXN and $180 MXN for single and double corolla, respectively. The target market is Mexico City, Oaxaca and the local market of each producing state.

Besides the cost of the bulb, there are rot problems provoked by bacteria in imported bulbs; if the plant is not sold in the first cycle and stays; at the following flowering the size of the flower will be smaller, possibly due to the lack of cold hours. If less than 200 bulbs are acquired, assorted colors will be sent; you can select a specific color if you buy 200 pieces of each color.

Hippeastrum production in Mexico has total dependence on foreign, because of the need to import the bulbs. Therefore, it is necessary to have efficient methods and techniques of propagation to multiply cheaply the bulbous species of commercial interest, to boost the production of bulbs that can be offered to national consumers.

As had been pointed out, the options for the plant propagation of bulbs are limited to one or two bulbils per plant per year in natural conditions, so it is necessary to search for cloning options, where no sophisticated equipment and techniques are required. Therefore, the objective was to evaluate different cutting methods of the mother bulb to induce the formation of bulbils and determine which method is better for the propagation of Hippeastrum.

 

MATERIALS AND METHODS

The research was conducted in a greenhouse covered with white plastic uv 2 and the Laboratory of Plant Propagation of the Faculty of Agricultural Sciences of the Universidad Autónoma of Morelos, located at 18° 58' 54.71'' N and 99° 13' 59.14'' W, and 1,876 m of altitude, in Cuernavaca, Morelos. The climate is semi-warm and subhumid, annual rainfall of 1,061 mm, average annual temperature of 20 °C, (A)Ca(w1)(w)(i')gw' (García, 1981).

 

Plant material

Hippeastrum bulbs (8 cm diameter) variety Pasadena were used. The bulbs were prepared by removing the roots, then cut according to the treatments evaluated (Figure 1): 1) the whole bulb, 2) basal section, 3) ^ cut in basal section, 4) basal section without central bud, 5) cutting basal section in half, 6) basal section into quarters, 7) longitudinal cut into quarter, 8) longitudinal cut into eighths and 9) basal section into quarters, separating each quarter into five groups of twin cataphylls.

The bulbs (or fractions) were planted in 7" black plastic pots containing compost of sifted tree leaves. A bulb or sections obtained were planted per pot. The depth of planting was to cover the bulb or sections with the substrate used.

After planting, we had to wait five days for healing of cuts; then irrigation was applied using water with fungicide Captán^® (2 g∙liter^-1, active ingredient: N-trichloromethyl dicarboximide); the fungicide application was repeated the first two weeks after planting (once a week); then watered twice a week during the seven months of experimentation.

 

Experimental design

The experiment was conducted as a completely randomized design with five replications per treatment; a replication was a pot with one bulb or sections, according to the treatment.

The evaluation was conducted at seven months after the establishment of the experiment, recording: 1) bulbils per mother bulb, number of bulbils provided by each mother bulb; 2) bulbil weight, weight of fresh mass of the bulbil using an analytical balance; 3) bulbil length, the length of the bulbil was measured using a digital vernier; 4) bulbil diameter, measured with digital vernier and the equatorial diameter of each of the bulbils; 5) roots per bulbil, the number of roots per bulbil; 6) leaves per bulbil, the number of leaves produced by each plant.

 

Data analysis

The data were evaluated using the analysis of variance, mean comparison test of Tukey (P ≤ 0.05), and correlation. The variables evaluated were transformed with the , function prior to statistical analysis.

 

RESULTS AND DISCUSSION

Three bulb cutting method (whole bulb, basal section and ^ cut of the basal section), showed no formation of new bulbils from the mother bulb; in the three cutting methods, the central bud of mother bulb was not damaged, provoking that only a single plant grew up from the mother bulb and no new bulbils were formed, showing effect of apical dominance by not allowing the buds to grow at the base of the bulb. In this regard, Azcón-Bieto and Talón (2008) indicate that it has been found that the apical bud may inhibit the polar transport of the endogenous auxin in lateral buds, transportation that would be essential to its growth, because these regulators stimulate especially the growth of the stem and inhibit the growth of lateral buds. Therefore, Hippeastrum bulbs with main bud had no growth of buds among cataphylls and thus no new formation of bulbils.

This result agrees with Schiappacasse et al. (2002) who suggest that undivided bulbs of Phycella australis increased in size, but rarely produced bulbils. In this regard, Kariuki (2008) reports that by eliminating the main bud of the bulb of Ornithogalum more bulbils were obtained.

The analysis of variance showed highly significant effect (P ≤ 0.01) of the bulb cutting method in all variables (bulbils per bulb mother bulb, bulbil weight, length, diameter, roots and leaves) evaluated in the propagation of bulbils. The coefficients of variation were 3.66 to 7.56 %, while the determination coefficients were greater than 0.90, indicating little variation in the observations and good fit of the statistical model used.

 

Bulbils per bulb

When the basal part of the bulb was used, eliminating the central bud cutting in half and into quarters, five and six new bulbils per mother bulb were obtained; on the other hand, when the whole bulb was used and longitudinal cuts were made to obtain four and eight bulb sections, the double of bulbils (10.5 and 13.7 new bulbils respectively) was obtained; this indicates that reserve source contained in cataphylls of the mother bulb had an important role in the formation of new bulbils, when cataphyll was longer (with more reserves) more bulbils were formed; Stancato, Mazzafera, and Magalhães (1995) indicate that the reserves contained in Hippeastrum bulbs are starch and sucrose, whose proportion varies depending on whether the bulb is source or demand. The bulb is demand when it is still growing, and becomes a source when it has finished growing. However, when only the basal section of the mother bulb was used cutting into four equal parts and each quarter was separated into five groups of twin cataphylls (with 20 bulb sections), 25.6 new bulbils were obtained, value that was statistically higher than that obtained in all other cutting methods (Figures 2 and 3).

Stancato et al. (1995) reported that during the formation of bulbils (125 days in culture for propagation), cataphylls of the mother bulb had 75 % weight loss in dry matter and 85 % starch content, indicating that the reserve source was used for the formation and growth of new bulbils.

The above results indicate that the greater the number of cuts in the bulb, the greater the number of new bulbils, although these bulbils would be smaller. Moreover, Ephrath et al. (2001) report that when increasing the number of sections of the bulb Hippeastrum, greater number of bulbils was obtained; as opposed to this study, these researchers used complete bulb longitudinal sections, with or without separation of cataphylls in all cuts.

Zhu et al. (2005) cut the mother bulb into 8, 12, 16 and 32 complete longitudinal sections and found that the greater the number of segments increased number of bulbils was obtained per mother bulb (12.8, 18.0, 22.4, and 28 respectively). The results obtained by these researchers, for eight sections of mother bulb, were similar to the 13.7 bulbils obtained in eight sections of the bulb in this study. However, the number of bulbils produced was lower than that obtained by Yanagawa (2005) who used the method of twin cataphylls and found 35.6 buds per bulb and indicates the presence of basal plate is of fundamental importance for the formation of new bulbils.

 

Bulbils weight

The heavier bulbils (9.6 and 7.7 g) were those formed when the whole bulb with longitudinal cuts was used to obtain four and eight sections; on the contrary, the bulbils with less weight were formed when the basal section cut in half was used (2.2 g), basal section cut into quarter separating each quarter into five groups of twin cataphylls (2.5 g), and when the basal section was cut into quarters (3.4 g) (Figure 4). Witomska, Ilczuk, and Zalewska (2005) also found that smaller cut in the bulb (16 sections) produced lower weight bulbils.

The above results indicate that the growth of the bulbs was affected by the reserves contained in the mother bulb; when using the whole bulb with longitudinal cuts, allowed to dispose of all reserves contained in the bulb and bulbils were heavier; while, when only the basal section of the bulb was used, half of the reserves was discarded and therefore the bulbils had lower weight. In this regard, Ephrath et al. (2001) suggest that the smaller segments results in small amounts of nutrients to promote the growth of bulblets. Stancato et al. (1995) indicate that the nutritional reserve of the mother bulbs used for growth of the Hippeastrum bulbils was the starch, since they determined that the content of starch decreased 85 % during 125 days of growth of new bulbils of this species.

 

Bulbils length

It was observed that the bulbils were bigger when the basal section without central bud was used and when four longitudinal sections were obtained. On the other hand, smaller bulb were recorded in those produced when the basal section was divided in half, and when the basal section in quarter was used, separating each quarter into five groups of twin cataphylls. Smaller bulbils had also lower weight (Table 1, Figure 4). The shorter length of the bulbils is attributed to using only the basal section of the bulb where fewer starch is available for growth; so the same happened when separating into groups of twin cataphylls, the amount of starch available was limiting for growth.

 

Bulbils diameter

In four of the cutting methods of the mother bulb, the bulbils had of similar diameter (19 to 21 cm), with significant differences compared to those formed when using the basal section cut in half and when the basal section in quarters was used separating each quarter into five groups of scales, since the diameter of the bulbils was only 13 and 14 mm, respectively (Table 1).

The growth of new bulbils, given by the weight, length and diameter, depended on the size of the section used. The larger the section of cataphylls, the higher growth of bulbils and the smaller the size of cataphylls the lower the growth, as was also reported by Jamil Rahman, Rahman, and Gazipur (2014). Stancato et al. (1995) indicate that the starch of the mother bulbs is the reserve substance used in the initial growth phase, until bulbs have leaves photosynthetically active.

 

Roots per bulb

The number of roots was higher (43 and 44 roots) for longitudinal cut in eights, and for using quarters of basal section, separating each quarter into five groups of twin cataphylls (Table 1). With these cutting methods we also had the largest number of bulbils. The lowest number of roots was obtained for basal section without central bud, basal section in half, and basal section into quarters, in all three cases, only the basal section of the bulb was used; in these treatments was where the lowest number of bulbils was obtained. This indicates high association between these two variables, which was verified using the correlation analysis presented below. The formation of new bulbs leads to the generation of roots that allow independent growth of each bulb formed.

 

Number of leaves per bulbils

At the time of evaluation, most bulbils still did not show leaves; those that had leaves had one or two (Table 1, Figure 3), indicating that growth in weight, length and diameter was due to existing starch reserves in the mother bulb.

The analysis, considering all the variables, indicates that when using the whole bulb and cutting into quarters or eights (slices), this generates many new bulbils (10-13), with bigger size compared to when we obtain a large number of bulbils. Zhu et al. (2005) mention that when the mother bulbs are cut into many segments, more bulbils are obtained, but these bulbils are smaller, with less weight, smaller diameter and fewer leaves.

For propagation purposes, the best method to cut the mother bulb is cutting the basal section into quarters and separate each quarter into five groups of twin cataphylls, because larger number of bulbils is obtained although the small size of the bulbils could generate losses in field due to the lack of sprouting, or by drying them and thus generating crop losses, as in Narcissus (Hanks, 1993). Size will also affect the time required to have a mature bulb (Hanks, 1993); it is clear that small bulbs need more time to grow to market size (Zhu et al., 2005).

The bulbils from the cut method that produced more bulbils should grow longer in the field, compared with those from cutting methods that generated fewer bulbs. In this regard, it is important also to know the time required for the bulbils produced by the different cutting methods reach adult size, to choose the appropriate cutting technique for each situation.

 

Correlation of variables

The correlations that were significant and highly significant were positive. The number of bulbils formed per bulb mother was highly correlated with the number of roots (0.816), indicating that the greater number of bulbils, greater number of roots was obtained, this is because each new bulbil need water and nutrients to initiate growth independently.

The weight of the fresh matter of bulbils had high correlation with the length, diameter and number of leaves per bulbil, since when the weight of the bulbils was higher the parameters were also higher. There was also high and positive correlation between length and diameter of the bulbil, indicating that the larger the bulbil, the larger the diameter. Two other variables that were correlated positively were diameter and number of leaves, indicating that the higher diameter, the greater the number of leaves (Table 2). This indicates that the bulbils produced during propagation showed normal growth of the bulbs in the species evaluated.

 

CONCLUSIONS

Based on the results obtained and the conditions under which the research was conducted, it is concluded that the presence of the main bud of the bulbs inhibited the development of new bulbils and therefore, the propagation of them; the presence of complete cataphylls in longitudinal cuts favored the production of bulbils. To make more cuts promotes greater propagation of new bulbils; the propagation of Hippeastrum variety Pasadena was greater when the basal section of the mother bulb was cut into quarters and each quarter was separated into five groups of twin cataphylls.

 

ACKNOWLEDGMENTS

The authors thank the Programa de Fortalecimiento de la Calidad en las Instituciones Educativas (PIFI) and the Programa de Mejoramiento del Profesorado (PROMEP) and the Consejo Nacional de Ciencia y Tecnologia (CONACYT), for their support for the acquisition of equipment, materials and supplies needed for requiere absorber agua y nutrientes para iniciar un conducting this research. Crecimiento de manera independiente.

 

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