Red clover (Trifolium pratense L.) breeding II. A polycross progeny test behavior and its relationship with the polycross block

Fernando Ortega K.1, Rafael Galdames G. y Alfonso Aguilera P.

The experiment was carried out at Carillanca Experimental Station (INIA), Temuco, Chile, and it is part of a red clover (Trifolium pratense L.) breeding project. The aim of the project is to release cultivars with better survival of plants, forage yield and persistence than the national cultivar Quiñequeli. A polycross block (BPC) and polycross progeny test (TOP) were performed. This paper presents the information obtained in three seasons of evaluation (1990/91 to 1992/93) of 54 progenies, utilizing Quiñequeli as a control, and the relations between the BPC and the TDP.
The average accumulated mortality at the end of the first, second and third seasons was 15.7, 35.3 and 70.1 %, respectively. The final mortality of Quiñequeli (88.2%) was higher than in the progenies. The powdery mildew (Erysiphe trifolii Grev.) severity was 33 and 18% for the first and second seasons, respective/y, and it did not have negative correlations with productive parameters (P > 0.05). Average dry matter yield for each season was 35.0, 35.0 and 33.4 g/plant and from the second season onwards Quiñequeli had significant (P < 0.01) lower yield than most of the progenies. The estimated narrow-sense heritability for mortality was 20% while for powdery mildew it was 50%. The breeding methodology utilized is specially suitable for low heritability characters like mortality and forage yield.

Keywords: Trifolium pratense L., red clover breeding, mortality, polycross progeny test, heritability, synthetics.
1 Centro Regional de Investigación Carillanca (INIA), Casilla 58-D, Temuco, Chile.