Abstract

The main limitation of red clover (Trifolium pratense L.) worldwide including in Chile is the lack of persistence related to the high mortality of plants due to a complex of biotic and abiotic factors. We have demonstrated in various trials in Chile that red clover plant population is highly correlated with forage yield once the plant population has dropped to a certain level, from the second or third season onward, depending on the environment of evaluation. We have also found that in the south of Chile, among the biotic and abiotic factors affecting red clover survival, the curculionid Hylastinus obscurus (Marsham) is the main deleterious factor. However, because persistence is a complex trait, we have used a practical approach in our breeding program. We selected for general adaptability under field conditions and used a modified among and within half-family selection methodology, evaluating at the same time families as swards and spaced plants. This breeding methodology and strategy have yielded reasonable genetic gains since we started our breeding program in 1989 at INIA Carillanca, Chile. Since then, we have conducted five cycles of recurrent selection, and two cultivars have been released to replace the old cultivar, Quinequeli INIA. These are Redqueli INIA and, more recently, Superqueli INIA. Depending on location and trial, average forage yield of the newest cultivar Superqueli INIA has been 23-69% higher than Quinequeli INIA and 5-36% higher than Redqueli INIA; this difference increases in the third and fourth seasons. Superqueli INIA had four times the yield of Quinequeli INIA in the fourth season. Therefore, the average realised genetic gain has been 0.4-2.6% per year, depending on location, showing the effectiveness of the breeding methodology and approach used.