Single-plant selection within lentil landraces at ultra-low density: a short-time tool to breed high yielding and stable varieties across divergent environments

Nil -competition (ultra-low plant density) has been asserted to highlight individual genotypes of high yielding potential. This was tested on three lentil ( Lens culinaris Medikus) landraces originated from different regions of Greece, germplasm presumably comprising mixtures of homozygous genotypes due to the self-pollinating nature of the crop. Single-plant selection under ultra-low density (interplant distance of 50 or 80 cm) resulted in first- and second-generation sister lines. Progeny testing was conducted in three locations, while the final evaluation at farming density included an additional marginal environment. Wide interplant distance accelerated phenotypic expression of susceptibility to viruses, reflected by high coefficient of variation of single-plant yields. Compared to the mother populations, higher yields combined with reduced virus incidence was observed in the first-generation sister lines, and even higher yields in the second-generation lines partly attributable to further improvement of their sanitary status. Remarkably, at the farming density across five environments, second generation sister lines had mean grain yields by 8, 10 and 20% higher compared to their respective ancestors. Individual sister lines exhibited up to 32% higher yields and stability in ‘agronomic’ terms, i.e. on both the GGE biplot model and regression approach of G×E interaction. In conclusion, the procedure appears an efficient tool that allows the breeder to exploit the natural genetic variability within landraces and develop in short-time pure-line varieties adaptable to a wide range of conditions.