COMBINING APTITUDE FOR CHLOROPHYLL CONTENT IN MAIZE LINES S3 FOR THE 'BAJIO' OF MEXICO

The goal of this study was to determine the genetic components involved in the maize chlorophyll index. To achieve this, five lines of white maize inbreeding with S-3 were crossed to generate a complete diallel with Griffing's Method I. The F-1's obtained and their parents were evaluated in two planting dates to determine chlorophyll concentrations in the crop cycle using the SPAD-509 device, at vegetative stage (V6), early flowering (R1) and for 10 days thereafter. Genetic analysis was performed with the SAS Diallel Method-1 program. The results showed signficant differences (p <= 0.01) between genotypes for chlorophyll at the different phenological stages. Furthermore, the effects of general combining ability (GCA) and specific combining ability (SCA) were significant (p <= 0.01) in the assessments made, showing the existence of additive and non-additive genetic effects involved in chlorophyll content. Reciprocal effects were only present at the R2 stage. Strong inconsistency between GCA and SCA effects for chlorophyll concentration was observed, since the TNM-2 and TNM-5 lines have high GCA estimates and are involved in most of the crosses that lead to high ACE estimates, but also in crossings with negative effects.