Growth

The analysis of variance showed for the variety factor (VAR) highly significant differences in plant height (AP), stem thickness (GT) and number of leaves (NH), significant differences in number of bifurcations (NB) and non-significant differences in the number of flowers (NF). No significant differences were found with respect to the effect of the concentration of the nutrient solution (SN), only in NH the differences were highly significant (Table 1).

According to the results of the mean comparison test (Table 2), in the AP variable no significant differences were found due to the application of the nutrient solution, only significant differences were found between varieties. This indicates that the application of a high concentration of nutrient solution does not necessarily guarantee a higher AP, because as mentioned by ^{Magdaleno-Villar et al. (2006)}; ^{San Martín-Hernández et al. (2012)}, generally, when increasing the concentration of nutrients, the electrical conductivity (CE) tends to rise and reduces the absorption capacity of water and nutrients, which causes the growth of the plant to be limited.

On the other hand, Figure 1 shows the growth curves adjusted for PA, where it can be observed that the highest values were obtained in the treatment TL75% (173.9 cm), followed by the treatment TC75% (151.4 cm) and SL50% (138.8 cm). ^{Toledo-Aguilar et al. (2011)} reported plant height values in 49 native varieties of poblano chili pepper grown in open field, which ranged from 38 to 57 cm, the varieties evaluated in this study showed a height three times greater due to the conditions in which they were cultivated, which coincides with what was found by ^{Beltrán-Morales et al. (2016)}, who obtained high values in plant height in jalapeño chili pepper produced under greenhouse in contrast to those grown in field.

Figure 1 Growth dynamics of plant height in three varieties of poblano chili pepper, grown with three concentrations of the Steiner nutrient solution. 

Usually, in controlled greenhouse conditions, if the plant is subjected to a low light intensity, the internodes of the stems lengthen resulting in a higher plant height, for this reason one of the factors that should also be considered in the production of Capsicum is solar radiation because it directly influences the growth of the crop (^{Hernández-Verdugo et al., 2015}; ^{Alemán et al., 2018}).

In stem thickness, the analysis of variance showed significant differences for the VAR x SN interaction (Table 1), GT was favored in the San Luis variety (15 mm) compared to the local varieties, where an average stem thickness of 11 mm was obtained (Table 2). The data obtained are similar to those reported by ^{Elizondo-Cabalceta and Monge-Pérez (2017)}, who obtained values for stem thickness between 12.5 and 15.8 mm in 12 genotypes of sweet pepper grown under greenhouse conditions; on the other hand, ^{Moreno et al. (2011)} reported stem thicknesses ranging from 14 to 16 mm in 12 commercial varieties of bell pepper grown under greenhouse and hydroponics.

In Figure 2, it can clearly be observed that the outstanding treatments were SL100%, SL50% and SL75%, in contrast to the local varieties which presented lower values, such is the case of TC50%, however, they coincide with the range of values obtained for stem thickness from 8.3 to 12.6 mm in chili pepper plants grown under protected conditions (^{Moreno et al., 2014}).

Figure 2 Growth dynamics of stem thickness in three varieties of poblano chili pepper, grown with three concentrations of the Steiner nutrient solution. 

In NH, the results at 91 ddt are reported, because the maximum values for this variable were recorded during this sampling. The VAR and SN factors significantly affected this variable (Tables 1 and 2), it was found that the response of the poblano chili pepper varieties to the concentration of the nutrient solution was linear, as the concentration of the nutrient solution increased, the NH also increased. As indicated in Figure 3, the treatments that accumulated a higher NH were TC100%, TC75%, TL100% and TL75%, the lowest number of leaves corresponds to the treatment SL75%.

Figure 3 Growth dynamics of the number of leaves in three varieties of poblano chili pepper, cultivated with three concentrations of the Steiner nutrient solution. 

These results are similar to those published by ^{Fawzy et al. (2012)} in C. annuum cv ‘California Wonder’, who observed a higher vegetative growth in plants with the application of a 100% concentrated nutrient solution of chemical fertilizer. In addition, the index of leaf area in poblano chili pepper plants grown under greenhouse conditions indicates that a greater amount of foliage significantly influences the capture of light and CO₂, because absorbing a greater amount of photosynthetically active radiation, the foliar production and the synthesis of compounds essential for the development of the plant increase (^{Berrospe-Ochoa et al., 2015}; ^{Mendoza-Pérez et al., 2017}).

The variable number of bifurcations (NB) was different in the three varieties (Table 1), but there was no effect by the nutrient solution. In the Tlalancaleca variety, a higher value was obtained for this variable (47 bifurcations), compared to the Tlacotepec variety (44 bifurcations) and the San Luis variety (41 bifurcations). This response can be seen in Figure 4, where the treatments TL75%, TL100% and TC75% stand out, in contrast to the treatments SL50% and SL75%, as happened in AP, since NB is directly related to AP, because the higher the plant height, the highest the number of bifurcations, and, consequently, it could be expected that the number of fruits per plant will also increase since in each bifurcation, the plants can develop a flower that can become a potential fruit (^{Ponce et al., 2012}).

For NF, the results at 42 ddt are presented because at this stage the poblano chili pepper plants reached their maximum expression in this variable. NF showed statistically significant differences between the varieties evaluated, but not by the application of the Steiner nutrient solution (Table 1).

Figure 4 Growth dynamics of the number of bifurcations in three varieties of poblano chili pepper, cultivated with three concentrations of the Steiner nutrient solution. 

In Figure 5, it can be observed that throughout the crop cycle in the different samplings carried out, there was an increase and a decrease in the number of flowers, this because the plants had flower abortion and many of the flowers counted did not become fruit, therefore, the growth in this variable was not linear. ^{Reséndiz-Melgar et al. (2010)} mention that chili pepper plants have sympodial growth, and generally solitary flowers are produced in each bifurcation.

Figure 5 Growth curves of number of flowers, in three varieties of poblano chili pepper grown with three concentrations of nutrient solution. 

If the plants are allowed to grow freely, the first six to 12 flowers will set fruit, but the high demand for assimilates for their rapid growth causes abortion of a high percentage of the flowers generated subsequently. The main causal agents of flower drop are associated with high temperatures, low radiation intensity, presence of fruit in the rapid growth stage and various biotic agents (^{Moreno et al., 2011}; ^{López-Gómez et al., 2017}).

Yield

In this variable there were no statistically significant differences due to the application of the treatments (Table 3), the different concentrations of SN had no effect on yield. On the other hand, in the evaluated varieties there were significant differences as can be seen in Tables 3 and 4, where the yield was statistically higher in the commercial variety San Luis (1.42 kg plant^-1) followed by the varieties Tlalancaleca (1.05 kg plant^-1) and Tlacotepec (0.99 kg plant^-1).

The average yield reported for the poblano chili pepper crop produced in field varies from 1.4 t ha^-1 to 3.2 t ha^-1 (^{Velásquez-Valle et al., 2014}; ^{Pérez et al., 2017}) and according to the results obtained in this research, yields of up to 4 kg m^-2 can be obtained with native varieties of the region and 6 kg m^-2 with commercial varieties, data similar to those reported by ^{Mendoza-Pérez et al. (2017)} in the poblano chili pepper crop variety Capulín, ^{Ramos-Gourcy and De Luna-Jiménez (2006)} in three varieties of ancho chili pepper and ^{Aguilar et al. (2005)} in San Luis ancho chili pepper.

For the variable number of fruits, significant and highly significant differences were found (p≤ 0.05) between the three evaluated varieties of poblano chili pepper (Table 3), the highest number of fruits was obtained with the varieties Tlacotepec and Tlalancaleca (Table 4). The applied concentrations (50, 75 and 100%) of SN did not affect the variable number of fruits. According to ^{Martínez et al. (2018)}, the effect caused by Ca (NO₃)₂ in low concentrations consists in generating a higher production of fruits per plant since as this fertilizer increases, decreasing yields can be caused.

Fruit quality

The characteristics of fruit quality of poblano chili pepper were not affected by the concentration of the nutrient solution, according to the results of the mean comparison test, significant differences were present only in the San Luis variety (Table 5). In the creole varieties, 100% of the fruits had a weight between 80 and 110 g with the application of any concentration of SN, while in the San Luis variety, the highest number of fruits that were grouped between 80 and 110 g was obtained by applying SN at 75%. ^{Wamser et al. (2017)} indicate that high concentrations of nitrogen in the nutrient solution increase the quantity of fruits per plant because it is the main component that influences the increase of fruit yield; nevertheless, at high concentrations in the nutrient solution, it tends to decrease the fruit weight because of the increase in the electrical conductivity in the substrate solution.

On the other hand, ^{Ramírez-Luna et al. (2005)} presented similar results, who, in habanero chili pepper plants produced under greenhouse, obtained fruits of smaller size compared to those produced in field, because the plants received a lower intensity of light, this condition favored the development of plants with greater height, thin stems, but fruits of small size.

Regarding fruit length, there were significant effects due to the application of SN in the SL and TC varieties (Table 6), where the 100% concentrated nutrient solution promoted the longest fruits (12-14 cm) in both varieties. ^{San Juan et al. (2019)} reported that, in huacle chili pepper, they obtained a greater response in the variables length and width of fruit with the application of the Steiner nutrient solution with a higher concentration of nutrients.

In fruit width there was also no effect of SN, in the SL variety, SN at 100% caused the highest percentage of fruits with a thickness between 7 and 8 cm, in the TL variety more than 90% of the fruits presented a width less than 6 cm with any nutrient solution, while in the TC variety, SN at 50% led to the highest number of medium-sized fruits. ^{Santiago et al. (2018)} reported that the fruits of ancho poblano chili pepper grown in open field reached a length of 13.95 cm and a diameter of 6.25 cm, values that, although not obtained under the same conditions, are similar to those obtained in this work in the San Luis variety.