Introduction

The plants of the Malpighiaceae family are native of Mexico and Central America (^{Mezadri et al., 2008}, ^{Mondin et al., 2010}). The fruits have agronomic and commercial importance due to their morphological quality (^{Maldonado-Peralta et al., 2016}); high content of ascorbic acid, considering them an antioxidant or nutraceutical nutrient (^{Mezadri et al., 2006}; ^{Mondin et al., 2010}). The propagation method of these species is mainly by seeds (^{Junqueira et al., 2002}), implying hereditary segregation or heterogeneity in plant populations and fruit production and quality (^{Martins et al., 2000}); in addition, although the seed is highly viable (^{Maldonado-Peralta et al., 2016}), germination is low (^{Azerêdo et al., 2006}). On the other hand, vegetative propagation allows the species to conserve the distinctive characteristics of the genotype, observed in the parents through generations (^{Paiva et al., 2003}).

The use of cuttings is a classical propagation method, which promotes the multiplication of selected plants and maintains the desirable characteristics (^{Meletti, 2000}), resulting in more uniform plants with greater genetic stability and homogeneous production (^{Oliveira et al., 2003}). Several authors reported successful vegetative propagation in fruit species considered difficult to root, for example in Citrus (^{De Andrade and Martins, 2003}), anonas (^{De Figueirêdo et al., 2013}, ^{Junior and Martins, 2014}), Pouteria campechiana (^{Chiamolera et al., 2014}) Prunus salicina (^{Tonietto et al., 2001}) and the presence of leaves on the cuttings seams to indicate they promote the formation of roots (Costa Junior, 2000).

There are species that are difficult to emit roots, so in these cases it is necessary to use different techniques and rooting stimulants, such as indolebutyric acid, which has shown positive results in different woody species (^{Vernier and Cardoso, 2013}). The vegetative propagation presents complications, from environmental to those proper to the species, therefore it is necessary to look for appropriate forms and materials, which would improve the results of this propagation form; the use of auxins improves rooting of cuttings (^{Gontijo et al., 2003}), thus it is indicated that the use of growth regulators is one of the most studied aspects, because they make the process efficient, obtaining plants with greater aerial quality and roots (Bastos et al., 2009; ^{Takata et al., 2012}).

In rooting researcges of woody cuttings of acerola (Malpighia emarginata Sessé and Moc. Ex DC and M. glabra L.) in greenhouse with different substrates and growth promoters, it was found from 45 to 92% of rooted cuttings (^{Alves et al., 1991}; ^{Musser, 2001}) and in sub-apical stakes 96% of rooting was obtained (^{Gomes et al., 2000}). ^{Ribero-Maldonado et al. (2005)}, evaluated the rooting of apical cuttings with leaves of M. emarginata, in various substrates and IBA concentrations; with cane sugarcane and river manure, obtaining 97.5% of survival and 47.5% of rooted cuttings, due to the viability that was reached, it is necessary to consider it for future researches, and in sub-apical stakes of M. emarginata and M. glabra with leaves there was found 45.05 and 52.27% of rooting, respectively.

^{Bastos et al. (2004)} indicate that the classical method of commercial propagation is grafting, but this entails high labor costs; being the propagation by cutting an alternative that allows the obtaining of plants of better quality at a lower cost and with the desirable characteristics (^{Nacata et al., 2014}). The objective of this investigation was to evaluate the rooting of woody cuttings of two nanche species (Malpighia mexicana A. Juss. and Byrsonima crassifolia (L.) H.B.K.), collected in Santa María Zoquitlán, Oaxaca, Mexico, using shade and indolebutyric acid as a growth promoter.

Materials and methods

This research was carried out in the greenhouses of the College of Postgraduates, Montecillo Campus, Texcoco, Estado de México, in 2014. Malpighia mexicana A. Juss. was at rest and Byrsonima crassifolia (L.) H. B. K. in full production. Wild mother shrubs were selected from seed and without visual symptoms of phytosanitary problems, located on the Guilache hill of Santa Maria Zoquitlán, Oaxaca, located at 16° 35’ 33.34” north latitude, 96° 18’50.36” west longitude and an altitude of 1 333 m, average annual temperature of 31 °C, low deciduous forest area and dry tropical climate (^{INEGI, 2012}).

From the mother plants, on April 12^th, 240 woody cuttings of 20 cm each were wrapped in newspaper moistened with water and Captan fungicide 1 gL^-1, and transferred in 10 kg plastic bags. Indobutyric Acid (IBA) at concentrations of 1 000, 3 000 and 10 000 ppm was used as rooting promoters and a control without promoter were used and sown in peat with sand 1:1 (volume/volume). On April 13^th the experiment was established, the substrates were mixed, moistened to field capacity and filled with 5 L trays; the cuttings were washed, pruned and cut off the base to remove the oxidized area, then treated with IBA by impregnating 5 cm of the base with the corresponding concentration; they were immediately planted 10 cm deep in the substrate, each tray was labeled and placed in a transparent plastic bag, which was closed and tied to the top of the greenhouse to prevent the plastic from interfering with the cuttings. The trays were placed under shade treatments at 70 and 90% using black shade mesh, they were constantly checked for fungi or drought. ^{Gontijo et al. (2003)}; ^{Vargas et al. (1999)}, indicate that cuttings of woody species rooted for a longer time, show better results; the established cuttings did not move until the time of the evaluation, which was 7 months after (November 13^th).

A randomized complete block design (BCA) was used, the factors studied were: two species of nanche, four treatments of IBA and two levels of shadow, with factorial arrangement of treatments (2*4*2), from these combinations resulted 16 treatments, each with three replicates of 10 cuttings (experimental units). The response variables evaluated were: percentage of survival, sprouting, cuttings with callus and rooting, and number and length of roots, obtained from the total number of established cuttings. The data obtained in percentages were transformed using the ARCSIN function x100 an analysis of variance (ANOVA) and Duncan's mean comparison test (p≤ 0.05) were performed using the SAS^® 9.2 statistical package (SAS Institute, 2009).

Results and discussion

The two species survived seven months after the experiment was established (Table 1); in this variable, B. crassifolia and M. mexicana, did not show significant differences. The surviving cuttings showed shoots, but the percentage of cuttings with callus decreased, and also cuttings with roots. B. crassifolia did not present rooting. The normal propagation process in the two species of nanche is by seed, but with long germination periods, with results for B. crassifolia of 64.44% (^{Jaimes et al., 2014}) and for species of the Malpighia genus of 30% (^{Azerêdo et al., 2005}).

Table 1 Variables evaluated on cuttings of two species of nanche. 

Medias con letras diferentes en la misma hilera difieren significativamente (Duncan p≤ 0.05).

It is possible that more research will increase the success in nanche propagation; however, the results found in this paper show that these woody species when propagating them by cutting show difficult rooting, reaching barely more than 10% of survival and only M. mexicana showed roots. Research on macadamia nuts using semi-woody cuttings reached 10% of rooting (^{Bastos et al., 2006}). As a species that presents difficult propagation in this way, another feasible alternative to study in nanche is the realization of layers (^{Daneluz et al., 2009}), which has proved to be effective in macadamia nuts, with 25.3% of rooting, using 6 000 ppm IBA and 53.8% when the arrangements were made in December (^{Entelmann et al., 2014}), considering different times in nanche, and this allows different results to be obtained.

The species that grow in tropical and subtropical climates respond to shading, and better rooting results were obtained when 70% shade was used, with equal survival and sprouting of cuttings (Table 2), as well as the majority of cuttings showed callus when they were settled under this same shade level; however, with shade at 90%, there was little survival and under this condition there was no rooting. Studies in B. crassifolia show that rooting with shade at 70% is better than the 90% shadow (^{Duarte et al., 2003}), which coincides with what was found in this research.

Table 2 Rooting of cuttings of two species of nanche with different levels of shade. 

Medias con letras diferentes en la misma hilera difieren significativamente (Duncan p≤ 0.05).

Survival and sprouting in the two nanche species were better in the control than in the different concentrations of IBA (Figure 1), indicating that all live cuttings showed sprouting; however, among different AIB concentrations no statistically differences were found. ^{Gontijo et al. (2003)} used 2 800 mg L^-1 of IBA on acerola (M. glabra L.) cuttings with leaves and achieved up to 50% rooting, whereas when IBA was used at concentrations of 1 500 and 2 000 mg L^-1 and evaluated at 60 days, there were more than 80% of rooted cuttings, a situation that is contrary to this research, in which the rooting rates were low (^{Lopes et al., 2003}). This in turn shows that the use of IBA has an effect on rooting, because although the results shown were low, where it was not used, there was absence of roots.

Figure 1 Percentage in the evaluated variables of two nanche species, using different concentrations of IBA and a control without rooting promoter. 

The two species were statistically similar in callus stakes, where the control showed a higher percentage, followed by the use of 10 000, 6 000 and 3 000 ppm IBA, respectively. Situation contrary to the previous variable in the percentage of cuttings with roots, because the control did not show roots, and in M. mexicana with the three concentrations of IBA, although low, but there was rooting. Rooted cuttings with 10 000 ppm of IBA had roots of 2.78 cm on average, those with 6 000 and 3 000 ppm IBA were 1.13 and 0.78 cm, respectively. Research in acerola (M. glabra L.), using cuttings treated with 2 800 mg L^-1 of IBA, established in different substrates, have shown greater rooting (^{Silva et al., 2010}), so in nanche it is necessary to carry out further research to determine the substrate, type of cuttings and adequate environmental conditions to increase rooting.

In the interaction it was found that each species presented different behavior, with variations according to the shade and rooting promoters (Table 3). The two species established using shade at 70%, surpassed in most of the variables to those in the 90% shade; in addition, in B. crassifolia under 70% shade, where surviving cuttings also sprouted, whereas the higher the shade only the control survived

Table 3 Variables evaluated in the interaction of all studied factors. 

Medias con letras diferentes de las variables respuesta en la misma hilera difieren significativamente (Duncan p≤ 0.05). CV= coeficiente de variación

M. mexicana also showed the best behavior when the cuttings were planted under shade of 70%. In this species, the witness presented survival, sprouting and cuttings with callus but with no rooted cuttings, contrary situation was found in the cuttings with application of rooting promoter, where despite the low percentages, with the four concentrations of IBA some cuttings reached rooting, indicating that there was an effect of auxins on rooting, and with 10 000 ppm of IBA the roots were larger. Shade of 90% in the control and with 3 000 ppm of AIB in M. mexicana gave equal results for survival, sprouting and cuttings with callus but without root presence.

Conclusions

The two nanche species showed low survival and sprouting; however, in Mexico this is the first research that covers this subject, which allows it to be the base for future works, in addition these species are considered of difficult propagation, and rooting was only found in M. mexicana. In nanche, the use of rooting promoters is necessary for the obtaining of roots, in addition to that the propagation must be realized under shade. According to the obtained it is necessary to continue investigating, with different techniques of propagation, in different times of the year and with different materials, until finding better results.