Correlation and heritability estimates of maize agronomic traits for yield improvement and Striga asiatica (L.) Kuntze tolerance

Abstract

A study was carried out to estimate percent heritability and correlation coefficients of desirable maize agronomic characters under artificial infestation with Striga lutea. Forty five F1 hybrid maize of varied striga tolerance and their ten parents inbred were evaluated along with two check entries. This was sited in three locations representing different agro ecologies of south western Nigeria in 1999 cropping season. The results showed high and moderate heritability estimates of 94.0 and 40.0 for striga emergence count and striga syndrome rating respectively, while low heritability estimates of 13.0, 11.32, 16.0, 5.70 and 16.22% were obtained for tolerance index, days to tasseling, days silking, kernel rows/cob and grain yield respectively. Genotypic correlation coefficients of striga emergence count with maize agronomic traits were positive and significant, while phenotypic correlation between striga count and other maize agronomic traits were also positively and significantly correlated, except striga count which was negatively correlated with striga syndrome rating. On the other hand, maize ear aspect alone contributed 19.4% to grain yield, while inherent yield loss of 23.0% was estimated if striga is left uncontrolled. Parameter estimates revealed that all striga and maize agronomic traits were positively associated with grain yield except plant and ear heights under striga infestation. Although, implications of these estimates have been discussed, this study affirmed that genotypic and phenotypic correlation coefficients as well as heritability estimates were found suitable as models for yield improvement and selection for S. lutea tolerant genotypes. Key words: Heritability estimates, correlation coefficient, striga tolerance rating, grain yield.