USE OF CELL MEMBRANE STABILITY TO ESTIMATE HEAT TOLERANCE IN MAIZE

Abstract

To identify heat stress tolerant maize genotypes, based on the thermostability of the cellular membrane, and to determine the consistency of this test for its use in the prediction of productivity in the field under heat stress, two experiments were carried out during spring-summer 2005 and fall-winter 2006. In the first experiment, cellular membrane stability in response to high temperature was determined by measuring electrolyte leakage from leaves of plants under heat stress in 28 maize cultivars. In a second experiment, the contrasting genotypes C-3014 (tolerant) and F2 44x35 (susceptible) were compared under field conditions in Guemez, Tamaulipas, Mexico. Physiological traits, grain yield and its direct components were determined. According to the results, the genotypes were classified into twelve tolerant, nine moderately tolerant and seven susceptible to heat. Under field conditions, the grain yield of the tolerant genotype (C-3014) was 20\% higher than the susceptible one, as a result of a higher photosynthetic rate (29\%). The damage to the cellular membrane is a physiological approach appropriate for the selection of heat tolerant maize genotypes in the early stages of a breeding program.