HETEROSIS DE CRUZAS ENTRE LINEAS DE TOMATE (Solanum lycopersicum L.) NATIVO MEXICANO TIPO PIMIENTO Y LINEAS TIPO SALADETTE

Abstract

En México el tomate o jitomate (Solanum lycopersicum L.) es una de las hortalizas de mayor importancia por su superficie cultivada, por las divisas y el número de empleos que genera, y por su valor alimenticio y cultural. Sin embargo, el material nativo mexicano “criollo” se ha estudiado poco en cuanto a su rendimiento, calidad, resistencia a factores bióticos y abióticos, y en su potencial como fuente de germoplasma en programas de mejoramiento genético. En este trabajo se evaluó el comportamiento heterótico de 40 cruzas formadas entre 10 líneas S5 derivadas de colectas de jitomate nativo mexicano tipo pimiento, localmente llamado “chino criollo”, y cuatro líneas S5 derivadas de híbridos comerciales de jitomate tipo “saladette”. El experimento se estableció en condiciones de invernadero e hidroponía, en un diseño experimental de bloques completos al azar con tres repeticiones y cinco plantas por repetición. Las variables que se registraron fueron peso total de fruto (PTF), peso promedio de fruto (PPF), número total de frutos (NTF), firmeza del fruto (FF), número de flores del tercer racimo (NFR3), número de racimos por planta (NRP) y días a floración del primer racimo (DF1). Hubo diferencias significativas (P ≤ 0.01) entre genotipos, cruzas, líneas y grupos de materiales para la mayoría de las variables. La cruza de mayor rendimiento fue LOR111R, con 3624 g/planta, seguida del testigo El Cid con 34529 g/planta. En las variables PMF, NTF y NRP las cruzas al menos igualaron y en algunos casos superaron al híbrido testigo. Se obtuvieron valores positivos de heterosis media para la mayoría de las variables, excepto en días a floración. En el rendimiento de fruto la heterosis media varió de -21.8 a 111.2 %, mientras que para PPF fue de -13 a 80.7 %. Los resultados del comportamiento per se de las líneas y de sus cruzamientos indican una amplia divergencia genética, la cual se reflejó en altos rendimiento y alta heterosis media que se pueden aprovechar en programas de mejoramiento genético de jitomate.

Identification of Outstanding Saladette Tomato Lines With a Widened Genetic Base

“…In relation to DFR1, the 89 advanced lines behaved similarly to the commercial control, with flowering times ranging from 55 to 68 days from planting. This indicates that the first flower emergence was recorded on day 26 after transplanting, which is apparently earlier than what was observed by Vázquez-Martínez et al (2016), who recorded the beginning of flowering on day 76 after planting, i.e., 34 days after transplanting, in the F 2 that generated the current advanced lines. This is mainly attributed to the differences in planting dates and locations (Carrillo-Rodríguez et al, 2013) between studies, as both cases included the hybrid "El Cid" as a control, with the genotypes flowering similarly to the control.…”

“…These results confirm the potential for high yield of the new advanced lines, particularly those from initial crosses with the commercial hybrid Cuauhtémoc. Vázquez-Martínez et al (2016) found that the best initial crosses for the total weight of fruits involved native parents LOR111, LOR81, LOR79, LOR84, and LOR103 with commercial parents R and C. This study shows that the yields of the outstanding advanced lines involved the same commercial parents. However, three of those nine lines are from LOR85, indicating that it is a native parent that combines favorably with the parents from commercial hybrids.…”

“…The "bell pepper type" or "chino criollo" tomato is a native Mexican variety with similar characteristics to the "Saladette" tomato (Hernández-Bautista et al, 2014) and has the potential to be used as a source of germplasm to generate commercial hybrids (Bonilla-Barrientos et al, 2014). Vázquez-Martínez et al (2016) observed that some crosses between lines derived from native "chino criollo" germplasm (referred to as "widened genetic base lines" in this study) and lines derived from commercial "Saladette" hybrids presented a high yield potential, equal to that of commercial hybrid controls, such as the cross LOR111 x R, which yielded 3624 g per plant, in contrast to the commercial control, which yielded 3452 g per plant. These authors found that heterosis values were high and positive in most variables, with the exception of days to flowering, which correlated negatively with yield.…”

“…The greatest heterosis was obtained in the total weight of fruits and days to flowering. According to Vázquez-Martínez et al (2016), a nine-line derivation program began in segregating populations of the outstanding lines, which had 89 S4 lines. Based on the hypothesis that crosses between native populations and commercial Saladette hybrids generate outstanding offspring, the aim of this investigation was to identify and select advanced lines with a wide genetic base, derived from crosses between Saladette tomato and native "bell pepper" or "chino criollo" populations, to generate open pollination varieties and potential parents of Saladette tomato hybrids.…”