EVALUACION DE PROGENITORES DE CAÑA DE AZUCAR (SACCHARUM SPP.) A PARTIR DE LA CARACTERIZACIÓN DE SUS PROGENIES EN LAS ETAPAS INICIALES DE SELECCIÓN.

Síntesis

Por la importancia de la Industria Azucarera en nuestro país, se hace necesario la perfección constante de la actividad de mejoramiento genético de la caña de azúcar como vía para garantizar la existencia de un grupo de variedades de alto potencial productivo. En este contexto, el trabajo relacionado con la hibridación – selección juega un papel fundamental y dentro de ella la evaluación y selección de los progenitores que aportan las progenies como punto de partida para la obtención y recomendación de nuevas variedades.

Con el objetivo de evaluar un grupo de progenitores a partir de la caracterización de sus progenies, se efectuaron tres Diseños Genéticos Factoriales o Carolina del Norte II y las familias resultantes se estudiaron en experimentos llevados a cabo en las dos Estaciones Provinciales de Investigaciones de la Caña de azúcar de la provincia Holguín.

En las progenies resultantes se evaluaron varios caracteres, cuyos resultados permitieron arribar a conclusiones y recomendaciones precisas, entre las que se encuentran que para mejorar el comportamiento ante la roya, el brix refractométrico, y el diámetro de los tallos, los progenitores deben elegirse fundamentalmente sobre la base del grado en que ellos se expresan dichos caracteres, prestar una atención especial a la elección de los progenitores femeninos debido a su gran influencia en las características de los progenies resultantes, recomendación de un grupo de progenitores y familias destacadas por su habilidad combinatoria y los resultados de selección, la existencia de efectos importantes debido a las localidades y los ciclos y sus respectivas interacciones con las familias, en el comportamiento de estas, la necesidad de realizar estudios genéticos sobre la herencia y la habilidad combinatoria como base para la definición y ejecución de programas de mejora para líneas específicas, así como la utilidad del empleo de análisis univariados y multivariados en la evaluación de progenitores y progenies.

Parental evaluation in sugarcane (Saccharum ssp.) based on progeny characterization at the first selection stages

Summary

The main objectives of this work were the evaluation of a group of parental varieties from the sugarcane gene pool base on their progeny characterization, in their combining ability and selection results in different locations, planting and harvest dates; the characterization of those populations obtained, the relationships among them and their impact on parent and family selection; the confirmation of some fundamental aspects related to the mode of inheritance of several important traits and its application to parent evaluation and selection and finally the evaluation of the usefulness of uni and multidimensional analyses for family and parent study.

Progenies stemming from there parental groups crossed in all possible combinations within group were studied in 8 trials according to a North Caroline II or factorial design. The study was carried out at the seedling and stage in spring, carry over spring and winter plantings are Mayari and Cristino Naranjo, as plant cane and first ratoon.

Those traits functioning as selection criteria during the first stages were evaluated. Progeny populations were submitted to variance analyses to determine parent, locations and planting and harvest date effects and their interaction with families. The main statistics were estimated as were phenotypic correlation among traits, general combining ability of parents for he different characteristics through the parent-offspring regression coefficient and multidimensional analyses such as main components and discriminates factorial.

Based on the selection results and those of general combining ability for different characteristics, the best parental varieties were C1616-75, CP52-43, My54129, Pomex72, PR980 and Ja64-19 as female and C227-59, Ja60-5, My54129, C323-68 and C97-59; it is also recommended to exploit a group of combinations with good results; progeny performance regarding brix, stalk diameter and response to ruts is highly predictable based on parent performance.

Maternal effects were evident for stalk diameter and response to rust and in a lesser degree for brix and number of stalks, the latter underlines the importance of selecting proper female parents. Experimental sites and planting and evaluation dates and their interaction with families affected all traits evaluated. For this, parent and family evaluation must be based on the results of several selection stages, especially as ratoon, at the location and date in which the new varieties are expected to be planted. The possibility exists of achieving genetic advance through simultaneous selection for brix, cane yield components and rust resistance since no important restrictive association was found among them.

Results confirmed that selection for rust resistance must be performed among 3 and 6 months after planting in the locations studied. The utilization of uni and multidimensional analyses together proved to be useful since they allow achieving a more complete knowledge of progenies and parent effect. The development of genetic studies on the mode of inheritance and the combining ability as a complement of germplasm characterization is recommended as a means for improving breeding programmers directed to the obtention of specific lines.