Diallel Analysis of Severity Score and Defoliation Percent of Late Leaf Spot (Cercosporidium personatum) [Berk.and Curtis] Deighton]) on Peanut (Arachis hypogaea L)

---

Résumé

Peanut late leaf spot (Cercosporidium personatum) [Berk.and Curtis]
Deighton]) caused yield losses worldwide. An analysis of the genetic effects of
resistance to late leaf spot on peanut in a full diallel was performed using
Griffing (1956) and Hayman (1954) methods. The objective of the study was
to analyse the genetic potential of six parental lines and to determine through
severity score and percent defoliation how resistance was transmitted to their
descendants. The study found that the severity score gives a broad-sense
heritability of 90.2% and a narrow-sense heritability of 70.8%. Defoliation
indicated broad-sense heritability of 39% and a narrow-sense heritability of
40.6%. Graphical analysis revealed that resistance to the disease may arise
from a complex of dominant and recessive genes. GCA, SCA and Reciprocal
Combining Effect was highly significant for the severity score and no
significant for defoliation. Additivity have a preponderant influence on the
resistance gene expression and severity score appear to be first choice trait in
the diallel analyzes for resistance. This severity score better reflected
resistance it was more heritable and could be a trait of choice in the breeding
strategy to improve resistance to late leaf spot. NAMA, PC79-79, GM656
could be recommended in hybridization programs aimed at improving
resistance to late leaf spot.

Mots-clés

Late leaf spot, heritability, diallel, percent defoliation, severity score