Adaptation of lentil to Northern European agro-climatic conditions: effect of sowing time and sowing rate on lentil development, productivity and weed suppression

The agronomic, economic, and cultural significance of lentil positions it as a potentially valuable crop in Europe. Only a few studies have investigated lentil cultivation in the central and northern parts of Europe. This study assessed the phenological development, productivity, yield quality, and weed suppression of better adapted lentil varieties to cool, temperate climatic conditions at a latitude of 55 °N. The effects of three sowing times and three seed rates were investigated as important factors for lentil performance in organic farming systems. The length of the lentil vegetation period varied from 96 to 119 days at this latitude. The duration of the vegetative phase was shortened by 14-24% and the reproductive phase by 12-25% when sowing of lentil was delayed by 10 or 20 days. During the reproductive stage, delayed sowing times had a significant negative effect on pod and seed formation and grain yield. A delay of 20 days in sowing time produced 8.7% more non-productive branches, 37.5% more non-productive pods, and 9% lower 1000-seed weight. A delay in sowing time by 10 and 20 days decreased grain yield by 14% and 23%. However, sowing time had a significant effect on weed suppression. The number of annual weeds was significantly reduced by 31% when lentil was sown 10 days later and by 78% when it was sown 20 days later. Increasing the seed rate from 160 to 240 and later to 320 seeds m^-2 provided up to 200 kg ha^-1 yield supplement and reduced the biomass of annual weeds. This study showed that in organic farming systems, an average grain yield of 1578 kg ha^-1 could be obtained at a latitude 55 °N, suggesting early sowing at the end of April or the beginning of May, with high seed rates.