Nationality: SV

Thesis (M. Sc.) Fitomejoramiento

In the present study were evaluated recurrent selection cycles in the population 7 3 for stunt resistance, three cycles in 1991 and four cycles in 1993. Each cycles included one synthetic and one general composite and were contrasted with commercial checks tolerant to the disease and susceptible. The main objective of this study was evaluate the genetic progress getting at the stunt resistance after three and four cycles of the recurrent selection in the population 73, in which were planted six tests into contrasting environments from Central America (four in Nicaragua, one in El Salvador and another one in Guatemala), the design used was randomized block with six replications f or environment and were planted three tests with f our replications for environment (two in El Salvador and one in Veracruz, Mexico) in 1993. Traits measured were grain yield, percent stunt plant, percent rot ears, plant high, ear high and aspect at the ear. Combinating analyses of variance across environments for yield, percent stunt plants and percent rot ears presented significant (P0.05) for location, the synthetics of the differents cycles were significant (P0. 05) too. Lineal regression with three cycles was significant with a gain of 5.5 percent in yield for cycles and 8.4 percent of stunt resistance. It got a gain yield of 4.3 percent by cycle and 11.0 percent of gain in the disease resistance using four cycles, in general, the test environments were differents and recurrent selection had been effective to improve the population 73, because it increased the stunt resistance and the yield potential in grain.

Spanish

MX-UAAAN 1994 AGUILUZ M r

Thesis Collection

Thesis Supported by CIMMYT