Jatropha curcas belongs to the family Euphorbiaceae, native to Mexico and Central America, currently grows in tropical and subtropical regions of the world. It is a multipurpose plant, whose interest in recent years is related to its potential as a raw material for biodiesel production. The objective of this research was to evaluate the morphological and productive characteristics of accessions of non-toxic Jatropha curcas L., collected in different regions of Veracruz and that were propagated by seed in the central region of the state in 2019. The plant material consisted of 23 accessions with five repetitions, plants that were three years old. The variables recorded were: plant height, stem diameter, branches (primary, secondary, tertiary), leaf length and width, flower buds, number of clusters and fruits; length, width, color and number of seeds per fruit, in seeds the weight, length, width, thickness and total weight of seeds per plant were recorded. The analysis of variance detected significant differences (p≤ 0.05) between accessions for most variables. The principal component analysis, the first two explained 57.66% and 60.80% of the variation. In seed-propagated accessions, the outstanding variables were: flower buds, clusters, fruits and seed production (accessions I-34, I-32 and I-47). These accessions have the greatest potential and vigor to be included in a genetic improvement program. It is concluded that there is a wide morphological variation in the accessions studied.
morphological characterization, production, propagation
Jatropha is an oleaginous plant commonly known as physic nut, native to Tropical America, which belongs to the family Euphorbiaceae with approximately 188 species distributed mainly in tropical and subtropical regions of the world (Henning, 2004; Mabberley, 2005). It is a plant valued for its use in the production of biodiesel (Rajagopal, 2008). This species also has insecticidal and fungicidal properties (Nwosu and Okafor, 2007), is also used for food when it comes from non-toxic materials (Makkar et al., 2007) and for medicine when using the latex of its leaves (Mujemdar and Misar, 2004).
For that reason, species such as J. curcas require an agronomic characterization that allows knowing the constitution and functioning of its morphological components (Oliveira et al., 2009). This procedure describes the morphological, phenological and productive characteristics that distinguish one material from another within the same species (Valdés-Rodríguez et al., 2018). In recent years, this interest has already provided some findings regarding physiological, genetic, agronomic, agroecological and production characteristics of this species (Valdés-Rodríguez and Pérez-Vázquez, 2013; Zavala et al., 2016; Wencomo-Cárdenas et al., 2020).
Currently, works for the morphological characterization of J. curcas continue (Laviola, 2009), since the agronomic characteristics of J. curcas are diverse. This is due to its wide agroecological plasticity to develop under conditions of water stress (Trabucco et al., 2010; Pérez-Vázquez et al., 2013) and grow in infertile soils (Balota et al., 2011; Valdés-Rodríguez et al., 2020). Consequently, the objective of this research was to evaluate the morphological and productive characteristics of accessions of non-toxic Jatropha curcas L., located in the experimental field of the Veracruz Campus of the Colegio de Postgraduados.
Study area. We worked with J. curcas plants from the Germplasm Bank of the Veracruz Campus of the Colegio de Postgraduados. The temperature data were obtained from the meteorological station of the institution and correspond to the year 2019. The climate of type Aw (w) (i ́) g, which corresponds to warm subhumid with rains in summer, an average annual rainfall of 1 100 mm and with an average temperature of 26 °C and a temperature fluctuation of 5-7 °C, with 5% rainfall in winter (García, 1988). In the evaluation period, a maximum temperature of 36 °C during April and a minimum of 14 °C in January were recorded, with a rainfall of 206 mm in September. In the rainy season, a rainfall of 28 mm was recorded.
Vegetative material. We worked with 23 accessions of J. curcas, three years old, collected in the state of Veracruz. Fruits and vegetative material were collected in 2019, and from this the germplasm bank was established in 2020. The seeds were sown in polyethylene bags and transplanted into the field in March 2020. The experiment was established in 2020 under a randomized complete block design and 23 accessions per seed were established, with five replications. (Tables 1) shows the origin and geographical location of the accessions collected.
Soil analysis. A soil sampling was carried out in the germplasm bank, in a zigzag pattern at two depths (0-20 cm and 20-40 cm), which were sent to the water-soil and plant laboratory of the Colegio de Postgraduates, Veracruz Campus.
Morphological variables evaluated. The descriptors used were those indicated by Laviola (2009) and the Jatropha spp. Network (SAGARPA-SNICS 2014). The variables recorded were: plant height (PlH), measured from the base to the apex of the plant; stem diameter (SD) with a vernier at 10 cm from the ground; leaf length and width (LL and LW), the middle part of the leaf blade was measured; number of primary, secondary and tertiary branches (NB1, NB2, NB3), flower buds (NFB), clusters (NCL) and fruits (NF) per plant, length (FL), width (FW), shape (FS) of fruit and fruit color (FC) according to the Munsell table, seeds (NSF) per fruit.
The beginning of the recording of morphological variables began between May-October, performing a weekly sampling. In relation to the harvest of fruits, these were monitored every three days to obtain greater precision regarding the production of fruits per tree. The fruit harvest was carried out from May to October 2019, the seeds were extracted and dried at room temperature.
Production of seeds (PRS) per plant. The seeds were extracted manually and a sample of 30 seeds was taken randomly, for which the length (SL), width (SWi), thickness (ST) and weight (SWe) were determined. Statistical analysis. The data obtained were recorded in a spreadsheet of Excel Version 2010® and the analysis was performed using the program SAS (Statistical Analysis System) v. 9.4, an Anova and a Tukey mean test (p≤ 0.05) were carried out.
A principal component (PC) analysis was performed with all variables, and a correlation matrix using the Princomp procedure of SAS. The graphical representation of the principal components (PC1) and (PC2) aimed to identify similarities and differences between the accessions. Subsequently, a cluster analysis was carried out by means of the Euclidean distance and the clustering method of Unweighted Pair Group Method with Arithmetic Mean (UPGMA), with the statistical package Ntsys® (Rohlf, 2009).
The analysis of variance detected statistically significant differences between accessions in 10 of the 20 morphological descriptors evaluated, particularly for the variables plant height (p= 0.0001), leaf width (p= 0.0018), flower buds (p= 0.0001), clusters (p= 0.0001), fruits (p= 0.0001), number of seeds per fruit (p= 0.0001), seed weight (p= 0.0001), seed length (p= 0.0001), seed width (p= 0.0001) and seed production (p= 0.0001). According to the Tukey mean test (p≤ 0.05), the maximum values in plant height were: 3.13 m and 3.00 m in accessions I-77, I-13 and I-26B. Manurung (2007) mentions that J. curcas is able to reach between 3 and 5 m and even up to 6 m in height in full development, so there are differences between accessions of the same age. Accession I-77 showed the highest number of flower buds with 264.
The maximum value of clusters was for accession I-34 with 181.60. Accessions I-32 and I-34 stood out with the highest number of fruits per plant with 558 and 531. These results are higher than those reported by Machado and Suárez (2009), who indicate that an African provenance had 455 fruits 240 days after being established in the field. Machado (2011) reports 102 fruits for a one-year-old provenance from Cape Verde; Srivastava et al. (2011) report 210 fruits in three-year-old plants propagated by seed. Accession I-25 stood out in the number of seeds per fruit with an average of 2.8, a normal number of seeds per fruit, which coincides with what was reported by Basha and Sujatha (2007).
In seed characterization, accession I-22 stood out in weight with an average of 0.84 g, accession I-62 in length with 20.13 mm and accession I-34 with 11.01 mm in width. These values coincide with what was reported by Martínez et al. (2010) and Valdés et al. (2013), who mention an average weight of 0.84 g, 17.41 mm in length, and 11.45 mm in seed width. In production of seeds per plant, accessions I-34 and I-32 stood out with 754.1 and 667.6 g respectively.
These results are superior to those of Sosa-Segura et al. (2012), who reported 30 to 36 fruits per plant, in germplasm from Puebla and Morelos, a seed production of 39 to 50 g in one-year-old plants. These data, even though they are not comparable due to the age differences of the plants, are a reference on the productive behavior of J. curcas. Guerrero et al. (2011) mention that the morphological and productive characteristics of greatest interest are: seed length, seed width, ratio of length and width of seed, number of seeds per fruit, seed weight, number of fruits per cluster and number of branches per plant. The parameters obtained in the present morphological characterization are shown in Table 2.
| ACC | PlH (m) | LW (cm) | NFB | NC | NF | NSF | SWe (g) | SL (mm) | SWi (mm) | PRS (g) |
| I-04 | 2.53±0.3 ab | 14.44±0.7 ab | 167.60±41.7 ab | 101.40±34.2 ab | 368.40±124.1 ab | 2.47±0.1 ab | 0.68±0.02 ab | 18.61±0.2 cd | 9.94±0.2 de | 247.6±65.4 dc |
| I-05 | 1.68±0.9 ab | 15.29±0.5 ab | 57.50±6.4 ab | 37.50±16.3 ab | 118.50± 6.4 ab | 2.31±0.3 ab | 0.74±0.03 bc | 19.22±0.4 ab | 10.05±0.1 cd | 91.7±58.8 dc |
| I-08 | 2.60±0.4 ab | 13.70±0.8 ab | 197.00±68.7 ab | 91.00±32.6 ab | 304.80±102.0 ab | 1.97±0.3 ab | 0.69±0.04 f | 17.99±0.2 cd | 9.77±0.4 e | 173.3±79.8 dc |
| I-11 | 2.20±0.3 ab | 15.78±1.0 a | 55.67±18.3 ab | 64.00±69.4 ab | 99.00± 47.3 ab | 2.04±0.5 ab | 0.70±0.07 de | 18.14±0.8 de | 9.72±0.1 e | 51.3±47.9 d |
| I-13 | 3.00±0.3 a | 13.34±0.6 b | 163.20±33.6 ab | 134.60±35.4 ab | 382.20± 92.2 ab | 2.28±0.1 ab | 0.72±0.02 cd | 18.04±0.2 cd | 10.14±0.1 bc | 291.0±77.6 bc |
| I-14 | 2.54±0.2 ab | 13.22±0.7 b | 138.80±41.4 ab | 56.40±24.3 ab | 150.00± 57.1 ab | 2.22±0.2 ab | 0.81±0.04 ab | 19.07±0.5 bc | 10.17±0.2 bc | 147.2±79.8 dc |
| I-18 | 2.68±0.2 ab | 14.65±0.5 ab | 110.60±11.3 ab | 76.80± 7.9 ab | 251.60± 42.3 ab | 2.40±0.1 ab | 0.77±0.02 ab | 18.82±0.3 cd | 10.31±0.2 bc | 240.3±149.4 dc |
| I-22 | 1.99±0.5 ab | 14.76±0.9 ab | 46.00±1.0 ab | 39.50±50.2 ab | 142.50±188.8 ab | 2.08±0.0 ab | 0.84±0.0 a | 19.82±0.0 ab | 10.61±0.0 ab | 183.5± 0.0 dc |
| I-25 | 2.61±0.4 ab | 15.19±0.7 ab | 172.20±38.5 ab | 133.00±57.3 ab | 407.80±223.1 ab | 2.80±0.0 a | 0.74±0.02 bc | 18.47±0.2 cd | 10.10±0.2 cd | 374.3±191.1 cd |
| I-27 | 2.63±0.2 ab | 14.96±1.0 ab | 167.80±55.0 ab | 110.60±48.4 ab | 383.20±146.4 ab | 2.56±0.1 ab | 0.73±0.02 bc | 18.53±0.4 cd | 10.33±0.5 bc | 276.3± 84.9 dc |
| I-30 | 2.86±0.2 ab | 15.17±0.9 ab | 154.00±33.7 ab | 104.80±55.7 ab | 233.60±78.0 ab | 2.65±0.2 ab | 0.77±0.02ab | 18.27±0.2 de | 10.61±0.2 ab | 257.2± 56.6 dc |
| I-31 | 2.74±0.1 ab | 14.48±0.9 ab | 185.40±21.4 ab | 68.20±22.1 ab | 190.20±43.9 ab | 2.45±0.1 ab | 0.72±0.04 cd | 18.09±0.3 de | 10.00±0.3 cd | 70.8± 19.8 d |
| I-32 | 2.81±0.3 ab | 14.97±1.3 ab | 225.40±51.6 ab | 162.00±25.9 ab | 558.40±122.1 a | 2.64±0.1 ab | 0.78±0.03 ab | 18.56±0.4 cd | 10.77±0.2 ab | 667.6± 50.7 ab |
| I-34 | 2.89±0.2 ab | 15.43±1.0 ab | 198.80±62.4 ab | 181.60±58.1 a | 530.60±248.0 ab | 2.53±0.1 ab | 0.79±0.03 ab | 18.53±0.4 cd | 11.01±0.1 a | 754.1±398.2 a |
| I-41 | 2.91±0.1 ab | 14.67±0.9 ab | 191.20±47.2 ab | 95.60±49.3 ab | 371.40±219.3 ab | 2.42±0.2 ab | 0.76±0.01 ab | 18.31±0.5 cd | 10.56±0.1 ab | 361.2±191.1 bc |
| I-47 | 2.74±0.2 ab | 15.34±1.0 ab | 153.20±45.5 ab | 111.60±29.1 ab | 434.40±126.8 ab | 2.48±0.2 ab | 0.79±0.03 ab | 18.92±0.4 bc | 10.19±0.1 bc | 465.3±156.4 abc |
| I-48 | 2.60±0.2 ab | 14.73±1.2 ab | 128.25±34.4 ab | 99.25±6.8 ab | 396.75±84.0 ab | 2.43±0.1 ab | 0.78±0.03 ab | 18.63±0.5 cd | 10.19±0.5 bc | 286.5± 62.2 dc |
| I-62 | 2.50±0.2 ab | 14.38±0.8 ab | 144.00±50.0 ab | 88.80±18.5 ab | 377.00±101.4 ab | 2.50±0.2 ab | 0.81±0.05 ab | 20.13±0.2 a | 10.31±0.1 bc | 287.5± 90.1 dc |
| I-64 | 2.58±0.2 ab | 14.62±0.6 ab | 121.67±29.8 ab | 96.67±16.8 ab | 347.33± 88.9 ab | 2.63±0.2 ab | 0.73±0.02 ab | 18.20±0.1 de | 10.74±0.2 ab | 357.8± 99.4 bc |
| I-77 | 3.13±0.3 a | 15.48±0.2 ab | 246.00±38.0 a | 94.00±6.2 ab | 278.67±56.1 ab | 2.44±0.1 ab | 0.74±0.01 bc | 18.25±0.0 de | 10.22±0.0 bc | 239.0± 27.8 dc |
| I-80 | 2.87±0.4 ab | 14.63±0.8 ab | 167.80±89.9 ab | 66.20±22.0 ab | 158.40±89.9 ab | 2.24±0.1 cd | 0.76±0.01 ab | 18.59±0.2 cd | 10.07±0.2 cd | 125.1± 55.4 dc |
| I-26A | 2.64±0.3 ab | 14.30±0.9 ab | 135.00±26.0 ab | 99.00±18.0 ab | 288.33±46.3 ab | 2.76±0.1 ab | 0.75±0.04 bc | 18.85±0.5 cd | 10.31±0.3 bc | 294.8±146.8 bc |
| I-26B | 3.00±0.3 a | 15.11±1.0 ab | 191.60±57.7 ab | 117.00±25.2 ab | 381.44±130.2 ab | 2.76±0.1 ab | 0.78±0.03 ab | 19.02±0.4 bc | 10.29±0.2 bc | 360.8± 86.3 bc |
[i] Means with different letters in the same column are statistically different, according to the Tukey test (p≤ 0.05); ACC= accession; PlH= plant height; LW= leaf width; NFB= number of flower buds; NC= number of clusters; NF= number of fruits; NSF= seeds per fruit; SWe= seed weight; SL= seed length; SWi= seed width; PRS= production of seeds.
The first two principal components (PC) explained 57.66% of the total observed variation. The first component explained 34.84%, the second 22.82%. The variables with the highest descriptive value integrated in the PC1 are: number of clusters, flower buds, leaf length, plant height, number of fruits per plant and weight of seeds. The PC2 integrated the variables: seed weight, seed width, leaf width, seed length, seeds per fruit, secondary branches and seed thickness (Table 3).
The graphical representation of the first two principal components, group I was formed by the accessions I-34, I-32, I-26B, I-30, I-25, I-47, I-26A, I-64 and I-27, which were characterized by presenting a greater number of clusters, flower buds, leaf length, plant height, number of fruits per plant and weight of seeds.
Group II was formed by accessions I-22, I-62, I-48 and I-18, it was distinguished by presenting greater seed weight, seed width, leaf width, seed length, seeds per fruit, secondary branches, and seed thickness. In group III are accessions I-14, I-80, I-31 and I-04, this group presents intermediate values in stem diameter, fruit width, but lower values in clusters, fruits and seed weight. In group IV were accessions I-08, I-13, I-41 and I-77, this group stands out for presenting a greater number of primary branches, fruit color and fruit width, in addition to having an intermediate value in flower buds and seed weight (Figure 2).
The cluster analysis gave rise to the formation of four groups Figure 3, which differed in their conformation from those obtained in the principal component analysis. This difference is due to the fact that only the variables that explained PC1 and PC2 are used in the principal component analysis.
Likewise, in the cluster analysis, when using all the variables evaluated in obtaining the dendrogram, it was obtained that group I included I-04, I-27, I-13, I-48, I-62, I-18, I-26A, I-25, I-41, I-26B, I-32, I-47, I-64, I-30 and I-34, which were characterized by having stem diameter of 65.67 mm, length and width of leaf of 14.10 and 14.74 cm, 161.63 in flower buds, clusters of 114.18, number of fruits with 380.83, length and width of fruit of 30.21 mm-23.26 mm and seed weight with 368.15 g.
In group II was accession I-22, which presented 14.76 cm in leaf width, seed weight with 0.84 g, width 19.82 mm and with a thickness of 10.61 mm respectively. While in group III were accessions I-08, I-14, I-77 and I-80, this group stood out for presenting a high average in plant height with 2.79 m, secondary branches of 29.50 and flower buds of 185, finally in group IV was accession I-31, which was characterized by presenting a low seed weight per plant (Table 4).
Authors such as Machado (2011), in one morphological characterization of accessions of different provenances of J. curcas, in Cuba, propagated by seed, found significant differences in morphological characteristics of height, number of primary, secondary and tertiary branches. Steinmann (2002) states that propagation by seed has greater production and tolerance to pests and diseases. In this regard, it is recognized that their populations present a great variability in their morphological structures (Toral et al., 2008), which could be a limitation for their domestication.
Investigations such as those of Henning (2004); Achten et al. (2008) mention that flower biology and heterogeneity in production cycles are characteristics that need to be improved to make a commercial crop possible, but it still lacks information on growing conditions, input response capacity of production and seed yield. Francis et al. (2005) mention that plant yield will depend on the conditions of the growing area, as well as genetics, plant age and management. Soil analysis. The type of soil is loamy-clayey (García, 1988) with a pH that tends to be moderately acidic. The pH obtained was within the acceptable parameter for J. curcas, since it can be sown in marginal soils with a pH of 6 to 8 (Kumar and Sharma, 2008).
The soil used to propagate the seed had a high concentration of nitrogen (N), a component required at a high concentration (Achten et al., 2008). Regarding the presence of phosphorus (P), this was independent of the depth at which the samples were taken. The amount of potassium (K) was higher in the sample taken at a shallower depth (20 mg/L), and important to increase the size of grains and seeds and the displacement of starch, sugar and oil.
Regarding organic matter, this was 6.28% in the sample taken from 0-20 cm. The texture was loamy-clayey and clay. This is contrary to studies indicating that J. curcas develops better in sandy or gravel soils with good aeration and does not tolerate flooded soils (Noda-Leyva et al., 2015).
The use of morphological and productive descriptors allowed identifying outstanding accessions in the plants of the 23 accessions of non-toxic Jatropha curcas L.; based on 18 variables. The accessions I-34, I-32 and I-47 were the most outstanding, with respect to a greater production in seed, number of flower buds, clusters and fruits, being the variables of greatest interest, coming in the same order from the regions of Capital, Nautla and Olmeca. The plants had a greater development in terms of height, number of primary branches, secondary branches, number of flower buds, fruits and seed production. These descriptors are important for the characterization of outstanding germplasm of J. curcas to be included in a genetic improvement program.
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