SELECTION RESPONSE OF A TP-17 SORGHUM POPULATION FOR RESISTANCE TO Exserohilum turcicum (Leo y Sug.) AND FOR SHORT PLANT HEIGHT

Abstract

Sorghum in México and Jalisco have considerable grain yield losses because of the pets and diseases, especially leaf blight and root stalk. In this study we evaluated four individual selection cycles (C₀, C₁, C₂ and C₃) of the random mating population TP-17, for leaf blight Exserohilum turcicum (Leo and Sug.) and plant height. Selection was carrying out on male sterile plants under field conditions at Ocotlán, Jalisco, México from 1989 to 1991. In 1992 each of the four cycles was crossed to five tester A lines (E13A, B140A, ATX623, R5A and ATX627), and in 1993 and 1994, the four cycles and their crosses (in 1994 the tester A lines were also included), were evaluated in a randomized complete block design with four replications. Individual selection was effective to improve resistance to leaf blight and reduce plant height of TP-17 population per se in -0.223 units (scale 1 to 5) and -10.4 cm per cycle, respectively. The best indirect response in the selection to leaf blight was found with the susceptible ATX627 tester line, and for plant height reduction with ATX623 tester line. The best ACE for both leaf blight and plant height was the combination of C₃ with the tester line ATX627.