Received for publication: 30 May, 2013. Accepted for publication: 30 July, 2014. 1 Technical Department, INTEROC. Cota (Colombia). 2 Department of Agronomy, Faculty of Agricultural Sciences, Universidad Nacional de Colombia. Bogota (Colombia). gfischer@unal.edu.co 3 Advisory of Research Projects. Bogota (Colombia). Agronomía Colombiana 32(2), 188-195, 2014 Effect of NaCl salinity on seed germination and seedling emergence of purple passion fruit (Passiflora edulis Sims) Efecto de la salinidad por NaCl sobre la germinación de semillas y emergencia de plántulas de gulupa (Passiflora edulis Sims) Luis Ariel Montaña1, Gerhard Fischer2, Stanislav Magnitskiy2, and Guillermo Zuluaga3 ABSTRACT RESUMEN The purple passion fruit is propagated by seeds, but factors, such as hardiness and impermeability of the testa and salinity and pH of the soil, give rise to problems in germination and uniformity of seedlings. The objectives of the study were to evaluate the effect of different NaCl concentrations (0, 30, 60, 90, and 120 mM, corresponding to 0.8, 3.0, 6.0, 9.0, and 12.2 dS m-1) on the germination and emergence of purple passion fruit seeds. For the germination test, 50 seeds per Petri dish were used, which were watered with a saline solution weekly. A seed was considered germinated when the radicle reached 2 mm. In the case of seedling emergence, 50 seeds were sown in cleaned river sand at a 1 cm depth on polystyrene trays, covered with transparent plastic film. They were irrigated weekly with different NaCl concentrations and the electrical conductivity (EC) of the substrate was measured. A seedling was considered emerged when the hypocotyl was fully erect. The results showed significant differences, with germination being higher in seeds treated with 30 mM NaCl than in the control seeds, and no statistical differences for the 60 and 90 mM NaCl treatments. The emergence was significantly higher in the 0 (0.05 dS m-1 of the substrate) and 30 mM NaCl (0.71 dS m-1) treated seeds when compared with 60 mM (1.25 dS m-1), 90 mM (1.69 dS m-1) and 120 mM NaCl (2.30 dS m-1 of the substrate). There was a decline in the chlorophyll contents of the seedling cotyledons and an increased substrate EC with increasing NaCl concentrations. La gulupa se propaga mediante semilla, pero factores como la dureza e impermeabilidad de la testa, o edáficos como salinidad o pH del suelo, originan problemas de germinación y uniformi- dad de las plántulas. Con el objeto de evaluar la adición de NaCl en concentraciones de 0, 30, 60, 90, 120 mM, correspondiente a 0,8; 3,0; 6,0; 9,0 y 12,2 dS m-1, se midió su efecto en germinación y emergencia de la semilla de gulupa. Para la evaluación de la germinación se usaron 50 semillas por caja de Petri y se rega- ron hasta humedecer el papel filtro con las soluciones salinas semanalmente. Se consideró una semilla germinada cuando la radícula tuvo 2 mm. Para estudiar emergencia se sembraron 50 semillas a 1 cm de profundidad, en bandeja de icopor, llena de arena lavada de rio y cubierta con plástico transparente, haciendo semanalmente los riegos de NaCl por tratamiento y a su vez midiendo la conductividad eléctrica (CE) del sustrato. Se consideró una plántula emergida cuando el hipocótilo estuvo completamente erecto. Se encontraron diferencias significativas en germinación, siendo mayor en las semillas tratadas con 30 mM de NaCl que las del control, sin diferencias estadísticas con las de 60 y 90 mM de NaCl. La emergencia fue significa- tivamente más alta en semillas regadas con 0 (0,05 dS m-1 del sustrato) y 30 mM de NaCl (0,71 dS m-1) en comparación con 60 mM (1,25 dS m-1), 90 mM (1,69 dS m-1) y 120 mM NaCl (2,30 dS m-1 del sustrato). Se presentó una disminución de clorofilas en cotiledones de las plántulas y aumento de la CE del sustrato a medida que aumentó la concentración de NaCl. Key words: propagat ion, seed lings, sa lt st ress, rad icle, hypocotyl, chlorophyll index. Palabras clave: propagación, plántulas, estrés por salradícula, hipocótilo, índice de clorofila. Introduction Passif lora cultivation in Colombia is of great importance because it represents an important line in the fruit produc- tion sector (Jiménez et al., 2012). Also, this genus has a lot of diversity, which allows for providing a wide range of plants for the domestic and international markets. Purple passion fruit seeds are considered orthodox (Costa et al., 1974; IBPGR, 1985), implying that they can be dried to a 6-8% moisture content without affecting their viability and storage potential. The emergence of seedlings is pha- nerocotylar and epigeal. Passif lora sp. seed exogenous dor- mancy probably has combined mechanical and chemical dormancies (Miranda et al., 2009). They usually germinate 189Montaña, Fischer, Magnitskiy, and Zuluaga: Effect of NaCl salinity on seed germination and seedling emergence of purple passion fruit (Passiflora edulis Sims) between 20 and 30 d (Morton, 1987), with a germination percentage of 80-85%. In the field, the seedling emergence from fresh passion fruit seeds starts between 11 and 12.5 d after sowing (Miranda et al., 2009). In general, the germi- nation of Passif lora sp. seeds is slow (Delanoy et al., 2006; Meza et al., 2007). Taiz and Zeiger (2010) described two components of salin- ity stress (mostly high Na+ and Cl- concentrations) which are nonspecific (osmotic stress that causes water deficits) and specific (accumulation of toxic ions that disturb nutri- ent acquisition and that are cytotoxic (Munns and Tester, 2008). Salt stress induces various morphological, physiological and biochemical responses from plants, depending on the genotype and the stage of plant development (Wil- ladino and Camara, 2003). Plant growth is retarded by physiological processes, such as photosynthesis, stomatal conductance, osmotic adjustment, ion uptake, protein synthesis, nucleic acid synthesis, enzymatic activity, and hormonal balance (Parés et al., 2008). It also affects the transport process of water and ions, resulting in ion toxicity and nutritional imbalance (Larcher, 2003) and, consequently, vegetative growth variables, such as dry mass, plant height, and leaf area, are severely affected (Parés et al., 2008). Plants exposed to saline conditions are affected from ger- mination to more advanced stages of development. In the case of seeds, saline conditions slow down seed imbibition and, hence, there is a decrease in the speed of germination, because of the osmotic effect. The processes of cell division and elongation may also have abnormalities as well as the mobilization of reserves necessary for the germination process (González and Ramírez, 1996). In general, NaCl could affect seed germination in several ways: 1) gener- ate enforced seed dormancy, such as in Atriplex prostrata (Chenopodiaceae), a salt tolerant plant species (Khan et al., 2003), 2) provoke a delay in germination and a slow rate of germination (Kudred and Sener, 1990), and 3) cause seed death. In seeds of halophyte species, secondary dormancy could be induced when seeds are exposed to 1% NaCl (Ungar, 1991). In the passion fruit, Meza et al. (2007) observed that, at increasing salt concentrations of NaCl and KIO3 the germi- nation percentage was significantly and negatively affected. Emergence initiation and the time that elapses for the period of 10 to 90% emergence were unaffected; whereas, the percentage of total emergence tended to decrease sig- nificantly with an increasing total concentration of salts (Meza et al., 2007). According to Nyagah and Musyimi (2009), sodium chloride solutions reduced radicle growth and plumule growth in passion fruit seedlings. There was no seed germination at NaCl concentrations of 3.6, 5.4, or 7.2 dS m-1. The seed tolerance to salinity in germination is an ability to withstand the effects of high concentrations of soluble salts in the medium (Taiz and Zeiger, 2010; Goykovic and Saave- dra, 2007). The presence of salts in the medium decreases water potential, which results in a reduced availability of water for the seeds, so seeds must generate a sufficient osmotic potential to improve the water status of embryos and allow growth (Jones, 1986). Years ago, it was found that the majority of plants are more sensitive to salinity processes during germination and emergence than during the subsequent stages of growth and development (Ayers, 1950). Although there are several studies related to the effect of salt on different stages of development in Passif loraceae, in the purple passion fruit, this aspect has been little studied, that is, the tolerance to salinity at the early stages of growth and development of this plant is unknown. Materials and methods This research was conducted in the Laboratory and green- houses of Plant Physiology at the Faculty of Agronomy of the Universidad Nacional de Colombia, Bogota. Purple passion fruit seeds extracted from fruits at maturity stage 3 were used (Pinzón et al., 2007). Thirty fruits were used in the extraction of the seeds and the pulp was allowed to ferment for 4 d; then, the seeds were washed and al- lowed to dry for 4 d. The seeds were sterilized for 10 s with 5% sodium hypochlorite and, then, washed with distilled water. Germination For the evaluation of germination, 50 seeds were placed in Petri dishes and watered to moisten the filter paper with different concentrations of NaCl (0, 30, 60, 90, or 120 mM) (Tab. 1). Then, the Petri dishes were taken to a growth chamber with temperatures of 23/20°C day/night, 80% relative humidity and 12 h light (Sanyo Versatile test Envi- ronment Chamber-Kasay, Ettern Leur, The Netherlands). Once a week, the moistened filter paper was changed, ac- cording to each treatment, and the counting of germinated seeds was done every 4 d, starting from the baseline. A seed was considered germinated when a radicle length of 2 mm was obtained. 190 Agron. Colomb. 32(2) 2014 Emergence In the greenhouses, emergence tests were conducted. For this purpose, 20x20x5 cm polystyrene trays and cleaned river sand substrate were used. Fifty purple passion fruit seeds were planted per treatment at a depth of 1 cm and covered with a transparent plastic. The average temperature and relative humidity under the plastic cover were 16.8°C and 76%, respectively. The trays were watered once a week with NaCl salt solutions, according to the treatment (Tab. 1), ensuring that they were watered at near field capacity with additional irrigation with distilled water. The electrical conductivity (EC) of the substrate was measured weekly (Konduktometer Schott, Schott Geräte GmbH, Hof heim, Germany). Normal seedlings were considered as those that showed the potential for further development and gave rise to healthy plants when transplanted to a good soil and favo- rable environmental conditions. A seedling was considered emerged when the hypocotyl was fully erect. This factor was measured every 4 d from the start of the experiment. TABLE 1. Treatments and description of NaCl solutions used during the study. NaCl (mM) Electrical conductivity (dS m-1) Osmotic potential (MPa) 0 0.8 -0.02 30 3.0 -0.10 60 6.0 -0.21 90 9.0 -0.32 120 12.2 -0.43 Measurement of imbibition, electrical conductivity, and chlorophyll content At the baseline, the imbibition of the purple passion fruit seeds was assessed, with four seeds as a replicate taken for each treatment, from which the weights were obtained and averaged for each treatment. This measurement was performed every 4 d before the first seed germination. The rationale for this measurement was to show how the concentration of the NaCl solution affected the water absorption of the seeds and what impact this had on the germination. The measurement of the chlorophyll index content (SPAD units) was done with Minolta SPAD equipment at the end of the experiment. For this, in each treatment, two emerged seedlings were taken per replicate and the chlorophyll con- tent index was measured directly in the cotyledon of each seedling, obtaining an average per treatment. Experimental design The design used a randomized complete block with five treatments and five replicates, for a total of 50 experimental units, using a Petri dish (germination) and polystyrene tray with cleaned sand (emergence) as the experimental unit and the number of sampling times as blocks. The imbibition and EC data were analyzed using sampling as a replicate. Verification tests were performed on assumptions for para- metric analysis and processing of data for the variables that showed lack of normality. Once parametric assumptions of the evaluated variables were verified, descriptive statis- tics and analysis of variance, using the SAS® 9.0 statistical software (SAS Institute, Cary, NC), were carried out. For variables that showed evidence of significant differences, a Tukey’s multiple comparison test was used. In all tests, a significance level of (P≤0.05) was used. Results and discussion Imbibition and germination Seed imbibition was measured until 16 DAS (days after sowing), before germination, during which five samplings were taken to measure seed weight per treatment. In seed imbibition, there were no significant differences between the treatments for seed weight, using Anova. However, when performing data descriptive statistics (Tab. 2), the control and 30 mM NaCl treatment had the higher weight variation coefficients, at 10 and 9%, respectively, and the other treatments had a variation exceeding 6%. This shows that, with an increasing NaCl concentration, the process of seed imbibition decreased because the osmotic potential decreased in the growth medium and, hence, the water TABLE 2. Imbibition (expressed in seed fresh weight, mg/100 seeds) of purple passion fruit seeds subjected to different NaCl concentrations, as compared to the control (0 mM). Descriptor 0 mM NaCl 30 mM NaCl 60 mM NaCl 90 mM NaCl 120 mM NaCl Minimum 19.30 19.30 19.30 19.30 19.30 Maximum 23.10 22.90 22.00 21.40 20.60 Mean 20.94 20.76 20.56 20.42 20.06 Variance 2.01 1.84 1.13 0.61 0.23 cv (%) 10 9 6 3 1 191Montaña, Fischer, Magnitskiy, and Zuluaga: Effect of NaCl salinity on seed germination and seedling emergence of purple passion fruit (Passiflora edulis Sims) potential decreased (Martínez et al., 2011; Zekri, 2002), represented in the seed weight due to water absorption. According to our data, the treatment with the highest imbibition was the control, with a maximum of 23.10 mg, and the lowest weight was in the 120 mM NaCl treatment, with 20.6 mg, showing a trend in decreasing weight in in- verse proportion to the NaCl concentration in the medium. However, the average values of all treatments were found in a range of from 20 to 21 mg in weight, which was not statistically different. Figure 1 shows the cumulative germination in the treat- ments with different concentrations of NaCl in nine samples, performed at 48 d after placement in the Petri dishes. The germination presented sigmoid curves over time for each of the salinity treatments. The germination started at 16 DAS with the 0, 30, and 60 mM NaCl treat- ments and later for the 90 to 120 mM NaCl treatments, at 20 and 24 DAS, respectively. These results indicate that, as the NaCl concentration increased, there was a decrease in germination. After performing the analysis of variance, with germina- tion data transformed by the square root function, there was a highly significant difference (P≤0.0001) between the treatments, showing a higher germination for the treat- ments of 60, 30, and 90 mM NaCl than the control, with the lowest at 120 mM (Fig. 2). According to Larcher (2003), germination is more success- ful in salt-free settings or in those having extremely low saline conditions, but, in our experiment, the purple pas- sion fruit seeds in the 30, 60 and 90 mM NaCl concentra- tions did not germinate any differently than in the control, especially after 24 d, confirming the germination tolerance of this species to low and moderate salt concentrations as Miranda et al. (2010) observed in the cape gooseberry (Physalis peruviana). Figures 1 and 2 show important reductions in germina- tion rates in the purple passion fruit seeds subjected to the 120 mM NaCl concentration. In this case, Miranda et al. (2010) supposed that the seed osmotic adjustment was affected and that stress had possibly favored the entering of other ions into the seeds. The low humidity content of the seeds may have increased saline stress, causing a ces- sation of metabolism or inhibition of certain stages in the germination metabolic sequence (Smith and Comb, 1991). Meza et al. (2007), in Passif lora edulis f. f lavicarpa, ob- served the same trend and found that the germination decreased with increased salt concentrations. Studies in Brazil, using eight water EC levels (ECw) of between 1 and 8 dS m-1, showed that the seeds of passion fruits are moderately tolerant to salinity in terms of vigor and initial development of the plants (Loureiro et al., 2002). However, ECw of from 4.43 dS m-1 showed adverse effects on the germination of this species. Studies, in which seeds of various cultivars of Solanum lycospersicum were treated with increasing concentrations of NaCl, have shown that the germination rate decreased with increasing salinity and the germination period took longer (Singer, 1994; El-Habbasha et al., 1996; Cuartero and Fernández-Muñoz, 1999). In this study, the germination was slow, since, in the best of cases, it reached 50% in 48 DAS (Fig. 1), demonstrat- ing that the purple passion fruit seed germination was 16 20 28 44403624 32 48 0 100 140 20 120 80 60 40 Time (days) A cc um ul at ed g er m in at io n 0 mM 120 mM 90 mM 60 mM 30 mM a ab ab bc c y=-2.7302x2+15.621x-4.8844 R2=0.922 0 mM 30 mM 90 mM60 mM 120 mM 0 16 20 8 6 4 2 18 14 12 10 N um be r of g er m in at ed s ee ds Real data Transformed data FIGURE 1. Accumulated germination in each treatment calculated as a number of germinated seeds per 250 seeds subjected to different NaCl concentrations. FIGURE 2. Averages and trends in germinated purple passion fruit seeds subjected to different concentrations of NaCl, with real average data transformed by the square root function. Means with different letters indicate significant differences according to Tukey test (P≤0.05). 192 Agron. Colomb. 32(2) 2014 delayed. Cárdenas (2011) mentioned that Passif loraceae seed germination is slow. Delanoy et al. (2006) reported that curuba seeds began to germinate 9 d after the beginning of the trial and reached 50% germination after 1 month. However, the period and the germination percentage varied considerably according to the conditions under which the test was performed (Aular et al., 1996; Meza et al., 2007). It is noteworthy that the results of seed imbibition (Tab. 3) might have had a direct effect on the duration of the germination process and that, at concentrations above 60 mM NaCl, there was a substantially reduced variation coefficient of seed weight (imbibition). This might have re- duced the osmotic and water potentials in the Petri dishes, affecting normal water uptake in seeds, and was ref lected in the final percentage of germination, as shown by Meza et al. (2007) and González and Ramírez (1996). NaCl inhibits germination, not only due to the physiological drought caused by the reduced water potential in the medium, but also due to an increasing concentration of toxic ions in the embryo (Prisco and O’Leary, 1970). Electrical conductivity and emergence Analyzing the EC values of the cleaned sand substrate from the beginning, it was observed that there was an in- crease in EC as the NaCl concentration increased (Fig. 3). The Anova evidenced significant differences between the treatments (P≤0.0001) for EC of the substrate, showing that 120 mM NaCl had the highest EC as compared to the other treatments that had an average value of 2.30 dS m-1. The control had the lowest EC compared to the other treatments, with a value of 0.05 dS m-1. The 60 and 90 mM NaCl treatments differed significantly from each other, showing values of 1.25 and 1.69 dS m-1, in addition, the 60 and 30 mM NaCl treatments had values of 1.25 and 0.71 dS m-1, respectively (Fig. 3). The general trend of EC in the substrate was to increase in accordance with the NaCl concentration (Fig. 4 and Tab. 3). The general trend during the emergence matched a simple sigmoidal curve, with a slow phase at the beginning fol- lowed by a fast phase that varied according to the treatment (Fig. 4). In other words, the beginning of germination for the 0 mM NaCl treatment occurred at 30 DAS, at 38 DAS for the 30 and 60 mM NaCl treatments, and at 46 DAS for the 90 and 120 mM NaCl treatments, which affected the emergence percentage at 58 DAS, when they reached the maximum percentage of germination. Analysis of variance of the emergence showed a highly significant difference (P≤0.0001) between the treatments, with the treatments of 30 and 0 mM NaCl having the better FIGURE 3. Average electrical conductivity (EC) and trendline in cleaned sand substrate during the emergence of purple passion fruit seeds sub- jected to different NaCl concentrations. Means with different letters indi- cate significant differences according to Tukey test (P≤0.05). TABLE 3. Descriptive statistics of electrical conductivity (EC) in the substrate (dS m-1) during seedling emergence from purple passion fruit seeds. Descriptor 0 mM NaCl 30 mM NaCl 60 mM NaCl 90 mM NaCl 120 mM NaCl Maximum 0.06 1.04 1.61 2.13 2.75 Minimum 0.05 0.55 1.03 1.33 1.83 Mean 0.05 0.71 1.25 1.69 2.30 Variance 0.00 0.05 0.06 0.12 0.15 cv (%) 0.03 7.25 5.14 7.23 6.64 0 mM 30 mM 90 mM60 mM 120 mM 0 15 25 20 10 5 EC ( dS m -1 ) a b bc c d y=-0.0128x2+0.6238x-0.5314 R2=0.9969 FIGURE 4. Accumulated emergence of seedlings of purple passion fruit per total of 250 seeds in daily samplings, sown in polystyrene trays with cleaned sand and subjected to different NaCl concentrations. 30 38 44504634 42 58 0 160 200 80 60 40 20 180 140 120 100 Days A cc um ul at ed e m er ge nc e of s ee dl in gs 0 mM 120 mM 90 mM 60 mM 30 mM 193Montaña, Fischer, Magnitskiy, and Zuluaga: Effect of NaCl salinity on seed germination and seedling emergence of purple passion fruit (Passiflora edulis Sims) emergences, while the treatments of 90 and 120 mM NaCl had the lower emergences. The treatments of 60 and 0 mM NaCl did not present differences (Fig. 5). Increasing NaCl concentrations in the substrate caused a negative effect on the emergence percentage and rate of the purple passion fruit seeds, which was more noticeable starting at thirty days after planting. Some authors have reported the same, such as Meza et al. (2007), who studied passion fruit seeds sown in coconut fiber and cleaned river sand at a 2:1 ratio with different levels of salinity, finding significant differences between the treatments. Salinity produced an appreciable effect on the duration of the emergence, which was, ultimately, negative, i.e. the total emergence had a inversely proportional trend to the increase in NaCl concentration , especially when it exceeded 90 mM in the substrate (Figs. 6 y 7). In this regard, Zekri (2002) reported that the emergence in Citrus sp. seeds decreased directly proportional to increasing salinity levels, noting that this trend was less consistent in ‘Cleopatra’ mandarin because this rootstock exhibited a higher salt tolerance. Hadas (1977) reported that the germination process is in- hibited from the time the seed is not able to take up water by imbibition, causing delays in the metabolic activation necessary for the emission of the radicle and subsequent mobilization of reserves in different seed parts (Jamil et al., 2006), and by excessive absorption of toxic ions, specifi- cally Na+ and Cl- (Prisco and O’Leary, 1970). Therefore, a positive relationship can be seen between germination and y=-0.6982x2+0.4068x-16.735 R2=0.9092 ab a b c c 0 mM 30 mM 90 mM60 mM 120 mM 0 16 20 18 14 12 10 8 6 4 2 N um be r of e m er ge d se ed lin gs y=-3.1429x2+12.717x-32.94 R2=0.9687 0 mM 30 mM 90 mM60 mM 120 mM 0 40 50 45 35 30 25 20 15 10 5 C hl or op hy ll in de x FIGURE 5. Number of emerged purple passion fruit seedlings in clea- ned sand substrate under different NaCl concentrations. Means with different letters indicate significant differences according to Tukey test (P≤0.05) FIGURE 6. Purple passion fruit seedlings subjected to different NaCl concentrations at 58 DAS. FIGURE 7. Chlorophyll content index (in units SPAD) in emerged cotyle- dons of purple passion fruit seedlings in cleaned sand under different NaCl concentrations. O mM 3O mM 6O mM 9O mM 12O mM 194 Agron. Colomb. 32(2) 2014 seedling emergence, which is demonstrated by the data in this study, which show that the increasing NaCl concen- tration (in the Petri dishes and in the substrate) not only affected the germination percentage but also negatively impacted the emergence of the seeds, which may indicate the toxic effects of NaCl. Chlorophyll in cotyledons The measurement of chlorophyll content in the cotyledons at the end of the experiment indicated that, as the NaCl concentration increased in the substrate, there was a clear decrease in the index of chlorophyll content (Fig. 7). Some studies have shown that salinity affects the chloro- phyll content in plants of agricultural interest. Argentel et al. (2009) determined the chlorophyll content and ion accumulation in various organs of wheat plants of the variety Cuban-C-204 by applying different levels of NaCl, adjusted to 4.8 and 12 dS m-1; they found a decrease in the chlorophyll contents as the salt concentrations increased, which was significant only between the control (0.02 dS m-1) and the 12 dS m-1 treatment; the chlorophyll content decreased significantly when the EC exceeded 8 dS m-1. Studies on the effect caused by salinity on the photosyn- thetic pigment concentration are abundant and coincident and tend to show that the damage is mainly due to the destruction of chloroplasts and increased activity of the enzyme chlorophyllase, affecting the synthesis of chloro- phyll (Flowers and Yeo, 1986; Appels and Lagudah, 1990). Conclusions Increasing NaCl concentrations significantly affected the accumulated germination and the percentage of germina- tion in the purple passion fruits, especially at the higher levels of 90 and 120 mM, equivalent to 9.0 and 12.2 dS m-1, respectively. The NaCl concentration in the substrate had significant dif- ferences for the EC, showing a proportional trend between treatments, being higher for the 120 mM NaCl treatment with 2.3 dS m-1 and lower for the control with 0.05 dS m-1. The emergence of purple passion fruit seedlings was signifi- cantly affected by increasing salinity levels in the substrate, with the lower percentages of emergence occurring with the 90 and 120 mM NaCl treatments, equivalent to 1.69 and 2.3 dS m-1 in the substrate, respectively. The different NaCl concentrations in the substrate had negative effects on the chlorophyll content in the seedlings, showing a clear decrease with increased NaCl concentra- tions, with the lowest rate at 120 mM. The ability to germinate and emerge under low saline stress conditions could indicate that the purple passion fruit pos- sesses a genetic potential for salt tolerance, at least during the first developmental stages. According to Miranda et al. (2010), this behavior does not necessarily suggest that plantlets initiated in saline stress conditions can continue to grow and complete their adult plant life cycle under these conditions. Literature cited Appels, A. and H.E. Lagudah. 1990. Manipulation of chromosomal segments from wild wheat for the improvement of breadwheat. Aust. J. Plant Physiol. 17, 253-266. Argentel, L., D.R. López, L.M. González, R.C. López, E. Gómez, R. Girón, and I. Fonseca. 2009. Contenido de clorofila e iones en la variedad de trigo harinero Cuba-c-204 en condiciones de estrés salino. Cultivos Trop. 30, 32-37. Aular, J., A.D. Bautista, and N. Maciel. 1996. 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