Respuesta de seis líneas F6 de arroz (Oryza sp.), ante los patógenos frecuentes del tallo y del grano, en la zona de Yaguachi, provincia del Guayas, Ecuador

This research was carried out in the coastal region, Guayas province, San Jacinto de Yaguachi canton, located at Latitude: 2 ° 5'48.5 '' S and Longitude: 79 ° 41'41.4 '' W; it has a territorial extension of 512.56 km². Its cantonal head is located 20 km from Guayaquil, Ecuador, located at 15 m.s.n.m, mean annual temperature 24.5 - 26 ° C and mean annual rainfall 750 - 1342 mm. Six advanced F6 rice lines were used as plant material, of which four lines are derived from crosses of Oryza rufipogon G. x Oryza sativa L. ssp. japonica, two lines derived from japonica crosses, four parental lines and two commercial varieties (SFL-011 and FL Arenillas). The study factor was to evaluate the incidence and severity of frequent stem and grain pathogens in six advanced F6 lines of rice. In this study, the means comparison of the of the diseases incidence in the segregating populations of rice and controls cultivars, was carried out through a completely randomized block design with twelve treatments and four repetitions, the Tukey test 95% scatter grams and frequency analysis. To find the disease index (IE), a formula was used in which it represents both the incidence of the disease and the severity of symptoms IRRI (2002), after calculating the disease index (IE), the performed Analysis was the Relative Variability (%), in order to identify the lines that were less affected by the diseases evaluated in this study, for which an excel table formula was used, to represent the values in a scatter graph. To carry out this study, several agronomicals labors were carried out such as: land preparation, irrigation, fertilization, control of pest insects, weed control (manual), except the application of fungicides. Parametric visual evaluation tables were used to evaluate the diseases, in which the damage and severity scales of the different diseases that were evaluated during the cultivation phase are found. In addition, laboratory samples were collected in order to identify the causative agent. Relating the diseases evaluations ,the analysis of variance, it was evidenced that there is statistical significance, in: percentage of grain staining, number of panicles per plant, grains per panicle, percentage of sterility, plant gram yield, which indicates that the diseases evaluated in this study have a negative effect on performance decline. The relative variability (%) analysis was used for the selection of lines with a lower degree of infection, in which 6 lines less affected response were identified, within there are 2 treatments that show less affectation by diseases such as T9 PARENTAL PUYÓN, which shows tolerance to Rhizoctonia oryzae, T2 PUYÓN / JP002 P8-30552 shows tolerance to Sarocladium, and line T12 PARENTAL JP003, shows resistance to Gaeumannnomyces, and grain staining, in the analysis the control T7 SFL- 011 COMERCIAL, showed that it is moderately tolerant to Rhizoctonia oryzae, and Sarocladium oryzae, while T8 ARENILLAS COMERCIAL, is susceptible to the complex of grain staining according to IE.

This research was carried out in the coastal region, Guayas province, San Jacinto de Yaguachi canton, located at Latitude: 2 ° 5'48.5 '' S and Longitude: 79 ° 41'41.4 '' W; it has a territorial extension of 512.56 km². Its cantonal head is located 20 km from Guayaquil, Ecuador, located at 15 m.s.n.m, mean annual temperature 24.5 - 26 ° C and mean annual rainfall 750 - 1342 mm. Six advanced F6 rice lines were used as plant material, of which four lines are derived from crosses of Oryza rufipogon G. x Oryza sativa L. ssp. japonica, two lines derived from japonica crosses, four parental lines and two commercial varieties (SFL-011 and FL Arenillas). The study factor was to evaluate the incidence and severity of frequent stem and grain pathogens in six advanced F6 lines of rice. In this study, the means comparison of the of the diseases incidence in the segregating populations of rice and controls cultivars, was carried out through a completely randomized block design with twelve treatments and four repetitions, the Tukey test 95% scatter grams and frequency analysis. To find the disease index (IE), a formula was used in which it represents both the incidence of the disease and the severity of symptoms IRRI (2002), after calculating the disease index (IE), the performed Analysis was the Relative Variability (%), in order to identify the lines that were less affected by the diseases evaluated in this study, for which an excel table formula was used, to represent the values in a scatter graph. To carry out this study, several agronomicals labors were carried out such as: land preparation, irrigation, fertilization, control of pest insects, weed control (manual), except the application of fungicides. Parametric visual evaluation tables were used to evaluate the diseases, in which the damage and severity scales of the different diseases that were evaluated during the cultivation phase are found. In addition, laboratory samples were collected in order to identify the causative agent. Relating the diseases evaluations ,the analysis of variance, it was evidenced that there is statistical significance, in: percentage of grain staining, number of panicles per plant, grains per panicle, percentage of sterility, plant gram yield, which indicates that the diseases evaluated in this study have a negative effect on performance decline. The relative variability (%) analysis was used for the selection of lines with a lower degree of infection, in which 6 lines less affected response were identified, within there are 2 treatments that show less affectation by diseases such as T9 PARENTAL PUYÓN, which shows tolerance to Rhizoctonia oryzae, T2 PUYÓN / JP002 P8-30552 shows tolerance to Sarocladium, and line T12 PARENTAL JP003, shows resistance to Gaeumannnomyces, and grain staining, in the analysis the control T7 SFL- 011 COMERCIAL, showed that it is moderately tolerant to Rhizoctonia oryzae, and Sarocladium oryzae, while T8 ARENILLAS COMERCIAL, is susceptible to the complex of grain staining according to IE.

La presente investigación se desarrolló en la región costa, provincia del Guayas, cantón San Jacinto de Yaguachi, ubicado en la Latitud: 2°5'48.5'' S y Longitud: 79°41'41.4'' O; cuenta con una extensión territorial de 512.56 km². Su cabecera cantonal está ubicada a 20 km de Guayaquil, Ecuador asentada a 15 m.s.n.m., temperatura media anual 24.5 - 26 °C y precipitación media anual 750 - 1342 mm. Se utilizó como material vegetal, seis líneas avanzadas de arroz F6 de las cuales cuatro líneas son derivadas de los cruces de Oryza rufipogon G. x Oryza sativa L. ssp. japonica, dos líneas derivadas de cruces japónicas, cuatro líneas parentales y dos variedades comerciales (SFL-011 y Arenillas). El factor de estudio fue evaluar la Incidencia y severidad de patógenos frecuentes del tallo y del grano en seis líneas avanzadas F6 de arroz. (Oryza sativa L. ssp. japonica). En este estudio la comparación de las medias de la incidencia a las enfermedades en las poblaciones segregantes de arroz y variedades testigos, se realizó mediante un diseño de bloques completamente al azar con doce tratamientos y cuatro repeticiones, la prueba de Tukey 95% dispersogramas y análisis de frecuencias. Para hallar el índice de enfermedad (IE), se utilizó una fórmula en la cual representa tanto la incidencia de la enfermedad como la gravedad de los síntomas IRRI (2002), después de calcular el índice de enfermedad (IE), se realizó el Análisis de Variabilidad Relativa (%), con el fin de identificar las líneas que fueron menos afectadas por las enfermedades evaluadas en este estudio, para lo cual se empleó una formula en tabla de Excel, para luego representar los valores en un gráfico de dispersión. Para realizar este estudio, se efectuaron varias labores agronómicas como: preparación del terreno, riego, fertilización, control de insectos plaga, control de maleza (manual), excepto la aplicación de fungicidas. Para evaluar las enfermedades se utilizaron tablas paramétricas de evaluación visual, en las cuales se encuentran las escalas de daño y severidad de las distintas enfermedades que se valoraron durante la fase del cultivo. Además se recolectaron muestras para laboratorio, con el fin de identificar el agente causal. Relacionando las evaluaciones de las enfermedades, con los análisis de variancia se evidencia que existe significancia estadística, en: porcentaje de manchado de grano, número de panículas por planta, granos por panícula, porcentaje de esterilidad, rendimiento gramos planta, lo cual indica que las enfermedades evaluadas en este estudio, tienen un efecto negativo en la disminución sobre el rendimiento. El análisis de la variabilidad relativa (%), se utilizó para la selección de líneas con menor grado de infección, en el cual se identificaron 6 líneas que fueron menos afectadas dentro de las cuales hay 2 tratamientos que manifiestan menor afectación por enfermedades como son el T9 PARENTAL PUYÓN, el cual muestra tolerancia ante Rhizoctonia oryzae, el T2 PUYÓN/JP002 P8-30552 muestra tolerancia a Sarocladium, y la línea T12 PARENTAL JP003, muestra resistencia ante Gaeumannnomyces, y manchado de grano, en el análisis el testigo T7 SFL- 011 COMERCIAL, mostró que es moderadamente tolerante ante Rhizoctonia oryzae, y Sarocladium oryzae, mientras que T8 ARENILLAS COMERCIAL, es susceptible al complejo de manchado de grano acorde al IE.