Is Selection at Low Plant Density Effective? a Paradigm with a Lentil Landrace.

Absence of competition has been asserted to optimize plant selection within a lentil (Lens culinaris spp) landrace, particularly when tolerance to viruses is sought. Aiming to investigate the progress of selection at two very low plant densities, two non-replicated (NR-0) honeycomb experiments including 1000 plants each were established at the farm of the Fodder Crops and Pastures Institute in Larisa, Greece, at the ultra-low density (ULD) of 1.8 plants/m2 and the low density (LD) of 4.6 plants/m2. The famous for its quality landrace “Eglouvi” from Lefkada, Greece, was used as the source material. The mean yield per plant and coefficient of variation (CV) were 3.6 g and 162%, respectively, at the ULD, and 4.7 g and 140%, respectively, at the LD. Very low densities favoured aphid-transmitted viruses leading to huge pant-to-plant variability. Fifteen highest yielding and healthy plants were selected from each experiment, averaging 25.8 g, forming thus 30 single-plant sister lines. Progeny testing was carried out in honeycomb R31 experiments at two locations, Larisa (Site1) and Orestiada (Site2). There were no significant differences between the lines originated from the two density regimes. Four sister lines at Site 1 and five sister lines at Site 2 had higher yield against the mother population (up to 19.9% at Site 1, and up to 44.9% at Site 2). Five sister lines at Site 1 and eight at Site 2 had lower CV compared to the mother population (up to 27.5% at Site 1, and up to 24.1% at Site 2). Four lines were of the highest yielding and having the lowest CVs at both Sites. Conclusively, there was a sign of considerable improvement in the aim to obtain pure-line genotypes. The density regime did not affect the selection effectiveness; rather, at ULD lower yield and higher CV indicated higher spatial heterogeneity. This research has been co-financed by the European Union (European Social Fund – ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: THALES. Investing in knowledge society through the European Social Fund.